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J M Crowell

Publications and source records attributed to J M Crowell.

7 recordsLinked to original sources
PubMed1976

Pulse-height light-scatter distributions using flow-systems instrumentation.

Several laboratories have recently been making light-scatter measurements on cells and other particles using flow-systems instrumentation. We at the Los Alamos Scientific Laboratory, as well as others, have obtained multimodal pulse-height distributions in certain angular regimes from particles of supposedly uniform characteristics. Because it was assumed that multimodal distributions implied characteristics of multivalue, the accuracy of such data has been doubted. In the present work, pulse-height distributions anticipated on the basis of exact electromagnetic theory were calculated for particles of known characteristics. These calculated pulse-height distributions agree quite well with those obtained experimentally. Physical optics form the basis for the explanation of the complex pulse-height distributions obtained experimentally. However, the results of this study show that certain cautions are necessary in the interpretation of light-scatter data presented in this manner.

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PubMed1976

Gynecologic specimen analysis by multiangle light scattering in a flow system.

A flow-system instrument is described in which the laser light scattered by a mammalian cell is sampled simultaneously at up to 32 angles between 0 degrees and 21 degrees from the laser beam axis as the cell passes through the beam. The scatter pattern for each cell is stored by a computer for later analysis. Various data-processing techniques are discussed. Results of preliminary application of the instrument to the analysis of normal and abnormal gynecologic specimens are presented.

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PubMed1975

A flow-system multiangle light-scattering instrument for cell characterization.

A flow-system cell-analysis instrument is described in which cells from a heterogeneous population are characterized by their light-scatter patterns alone. As the cells pass at high speed through a focused helium/neon laser beam, the scatter pattern from each cell is sampled simultaneously at up to 32 angles between 0 degrees and 30 degrees with respect to the laser beam axis, and the scatter pattern for each cell is transferred to a computer. A mathematical clustering algorithm is used to determine the number of classes into which the cells can be divided, and a linear separation algorithm is used to find the boundaries between the classes. Preliminary results on exfoliated cells from gynecological specimens are presented. This technique may be useful for automated prescreening of gynecological specimens.

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PubMedDate not supplied

Cell classification by laser light scattering: identification and separation of unstained leukocytes.

We have used a flow-system cell sorter to separate unfixed, unstained human leukocyte cells into morphologically distinct populations based only on the intensity of 488-nm wavelength laser light simultaneously scattered by each cell at two different angles. Three populations were observed as distinct peaks in a two-parameter pulse-height distribution and were then physically sorted into separate classes and stained for cytological examination. The three groups consisted of lymphocytes, monocytes, and neutrophils. Each group contained between 77 and 98 per cent of a single cell type. Blood from an irradiated monkey was also sorted and showed the presence of a fourth peak which consisted of 61 per cent eosinophils. Thus, multiangle light-scattering information from unfixed, unstained cells may be a promising technique for rapid morphologic analysis and may have application, for example, as a highspeed automated leukocyte differential. We anticipate that this method may be useful in other clinical applications where morphologic differences are diagnostically important. One of the principal advantages of the method is elimination of fixation and staining of the samples; this is a nondestructive testing technique.

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