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Biomedical subjects

W Galbraith

Publications and source records attributed to W Galbraith.

50 records · Page 3Linked to original sources
PubMed1980

The energy distribution about the image of a point.

A mathematical formulation is presented of the three dimensional distribution of intensity in the image of a bright point. Other equivalent formulations have been described before, but this one appears to have certain practical advantages. The formulation has been used in computer programs to provide tomograms and isophote contour maps of the intensity distribution. A following paper will describe the application of the formulation to differential interference contrast-microscopy.

Light↗
PubMed1975

Improved isolation, separation and cytochemistry of living cells.

1. This paper describes improved methods of obtaining, purifying and studying bulk suspensions of isolated living hepatocytes and other cells of adult rats and urodeles. 2. The cells were isolated largely by dissolving the hepatic ground substance through the extracorporeal portal perfusion and further incubation of the excised liver with 0.05% collagenase and 0.1% hyaluronidase. The different kinds of cells were then separated from one another by counter-current centrifugation. The isolated cells were examined by differential interference, phase-contrast, amplitude-contrast, ultraviolet, fluorescence and electron microscopy. Various cytochemical tests were carried out. Whenever possible, for each method of examination, the isolated cells were compared with cells of the same kind which had not undergone isolation. 3. Dye-exclusion, lysochromy, fluorescence and differential interference microscopical analysis indicated viability rates between 75 and 99%. Succinate dehydrogenase activity was preserved at a high level in nearly all isolated cells. In hepatocytes, the essentially extracellular cells. In hepatocytes, the essentially extracellular 'soluble' alkaline phosphatase activity of bile canaliculi was retained. Living hepatocytes were studied by super-modulating methods of microscopy for the first time, with somewhat unexpected findings. It now seems probable that previous methods of tissue preparation produced gross alterations in hepatocyte mitochondria. The assessment of the viability of isolated cells was re-examined. 4. The methods described may permit a more meaningful correlation between biochemical, cytochemical, ultrastructural and biophysical findings than that obtainable by the use of current methods.

Acid Phosphatase↗
PubMed1975

The Denver universal microspectroradiometer (DUM). II. Computer configuration and modular programming for radiometry.

This paper describes and discusses for microscopists and spectroscopists the choice of computer equipment and the design of programs used in the Denver Universal Microspectroradiometer (DUM). This instrument is an accurate computerized photon-counting microspectrophotometer, microspectrofluorimeter and microrefractometer. The computer is used to control the operation of the system, to acquire radiometric data of various kinds, and to reduce, analyse and output the data in a readily usable form. Since the radiometer was designed to carry out many kinds of measurements in a variety of micro- and macroscopic specimens, and since different methods of microscopy or spectroscopy have to be combined in various ways fro the study of any one specimen, no single master-program could fulfill efficiently all foreseeable requirements. Therefore, the programming developed is interactive, modular, hierarchical and hybrid. Modular interactive programming makes it possible for almost any kind of main program, applicable to almost any kind of measurement, to be assembled quickly from a collection of hierarchical subroutines. Main programs are short and composed mainly of Fortran statements calling subroutines; subroutines, in turn, automatically call other subroutines over many levels. The subroutines are independently written and optimized for maximum operational efficiency in the computer system used, or for maximum ease of transfer to other systems. This approach to programming enables someone unfamiliar with computer languages to operate the radiometric system from the console of the CRT terminal. The writing of new main programs, by linking groups of existing subroutines, requires only a minimum acquaintance with Fortran; only the writing and revision of subroutines requires programming experience. Differences and similarities in the method of computer operation between the present system and other computerized radiometers are briefly discussed.

Computers↗
PubMedDate not supplied

Multiple spectral parameter imaging in quantitative fluorescence microscopy. I: Quantitation of bead standards.

Digitized images from fluorescence microscopy may suffer from nonlinearity of camera response to illumination intensity, from uneven spatial response of the camera, and from uneven illumination of the microscopical field. Structureless fluorescence standard slides are used to characterize the camera response. This information permits the images to be corrected for all the above errors, in one operation. The computer algorithms are described, and also those for thresholding and finding objects. The method is illustrated by tests using fluorescent beads.

Algorithms↗
PubMedDate not supplied

Error measures for objective assessment of scene segmentation algorithms.

Scene segmentation is an important element in pattern recognition problems. Previous efforts to evaluate and compare scene segmentation procedures have been largely subjective. Quantitative error measures would facilitate objective comparison of scene segmentation algorithms. A theoretical discussion leading to a new generalized quantitative error measure, G2, based on comparison of both pixel class proportions and spatial distributions of "true" and test segmentations, is presented. This error measure was tested on 14 manual segmentations and 40 gynecologic cytology specimens segmented with five different scene segmentation techniques. Results indicate that G2 seems to have the desirable properties of correlation with human observation, categorization of error allowing for weighting, invariance with picture size and ease of computation necessary for a useful scene segmentation error measure.

Autoanalysis↗
PubMedDate not supplied

Studies on Papanicolaou staining. I. Visible-light spectra of stained cervical cells.

This paper presents visible-light absorbance spectra of the nuclei and cytoplasms of ten types of cervical cells stained by the Papanicolaou technique, together with tables summarizing the data. It is concluded that for automated image processing of Papanicolaou smears the most suitable wavelengths are 531 nm to maximize the contrast of cell against background and a wavelength in the range 560 nm to 605 nm (with a mean at 575 nm) to maximize the contrast of the nucleus against the cytoplasm.

Carcinoma in Situ↗
PubMedDate not supplied

Studies on Papanicolaou staining. II. Quantitation of dye components bound to cervical cells.

Dye binding to Papanicolaou-stained cervical cells was quantitated with a spectral subtraction technique. It was shown that of the dye components of Papanicolaou stains only aluminum hematein, orange G, light green SF and eosin Y are bound to cervical cells and that their chromophores do not interact. Bismarck brown Y was not bound to cervical cells, which confirms the subjective findings of previous authors, and so it should be omitted. No evidence of substrate-related variations in dye polymerization was found. The proportions of the four dyes were found to vary considerably from substrate to substrate. Spectra are presented of (1) solutions of the component dyes of the Papanicolaou stain, and (2) cervical cells stained with these individual component dyes, for comparison with the full Papanicolaou technique.

Cell Nucleus↗
PubMedDate not supplied

Azure B-eosin staining of blood cells: the effects of variation in stain formulation and staining technique on stain performance.

A quantitative study of azure B-eosin-stained blood cells is reported. The effects of variation in stain formulation and staining technique on the binding of azure B and eosin by acidophilic, basophilic and neutrophilic substrates were measured by scanning microdensitometry. The variables considered were stain concentration (the azure B-eosin concentration ratio was constant), azure B concentration (at constant eosin concentration), eosin concentration (at constant azure B concentration), staining time, buffer pH, metal salt contamination, dye contamination, buffer concentration and fixation time. The last two were the only variables which failed to produce changes in dye uptake. Tentative explanations of the observed effects are advanced.

Azure Stains↗