Data compression: 8-dimensional flow cytometric data processing with 28K addressable computer memory.

A method of data analysis for flow cytometry is presented which enables up to eight-dimensional data to be handled by a microcomputer with 28K addressable plus a further 32K non-addressable memory. The multi-parameter coordinates are coded into single numbers using a minimal modification of the array vector mapping equation. These code numbers, each of which corresponds to a given set of coordinates, and then ranked in ascending order according to magnitude and the frequency of each code number is found. Following this step the code is then decoded by integer arithmetic into its original coordinates which are then packed, together with the frequency, into two, three or four 16-bit words depending on the dimensionality of the data set. A five-dimensional data set is used as the illustration. Three regions were set on one two-dimensional data space and the five mono-dimensional histograms, plus a different bivariate distribution, were extracted in a single pass through the processed data file. In addition to considerable space saving the technique has two further attributes, namely, increased speed with which the user can appreciate multiparameter data and the ability to analyse such data sets with a microcomputer.

A computer-based data analysis system for enzyme-linked immunosorbent assays.

A computerized system is presented for automating the data collection, processing, and displaying tasks involved in enzyme-linked immunosorbent assays. This system uses a through-the-well absorbance reader of microtiter plates interfaced to a minicomputer running the UNIX operating system. Optical density in each well of a 96-well microtiter plate is recorded as a function of time for up to 10 time points. These data are automatically transmitted to the remote computer. The rate of product formation is then calculated for each well, and a battery of analysis, display, and comparison programs can then be used by the researcher for data presentation. Using the initial rate of reaction as the basis for quantifying enzyme-linked immunosorbent assays focuses on the catalytic property of the enzyme and allows a large dynamic range of the assay on any plate. These programs can be adapted to virtually any mini- or microcomputer with a graphics display or a plotting device. Assuming moderately powerful computing hardware, throughputs of 50 plates per day are easily achieved. The programs work equally well with peroxidase, beta-galactosidase, or alkaline phosphatase conjugated second antibodies, and with whole cell or soluble antigens.

A computerized consultation service in reproductive toxicology: summary of the first five years.

A computerized consultation service developed by the Reproductive Toxicology Center, Washington, DC, provides summaries of the literature on more than 1300 chemical and physical agents. During the first five years of operation, the service was used to evaluate exposures in 1089 individuals. Only 3% of the exposures involved men. Of the 1053 exposed women, 85% were pregnant and 8% were planning pregnancy. In this latter group, potentially hazardous exposures were reported in 17%. Pregnant women were primarily exposed to medications, although exposures to chemicals at work and in the home constituted other important sources of inquiries. Excluding ethanol and tobacco, 19% of pregnant women were exposed to agents that are known or probable reproductive toxins. Ethanol exposure occurred in 27% of the sample and tobacco use was reported in 13%. These findings suggest that even women concerned about exposure to agents during pregnancy commonly use known or probable reproductive toxins. Physician access to reproductive toxicology information and patient education will be necessary to reduce these exposures.

An 8-channel neuron recording interface for a microcomputer (Apple II), designed to gather spike occurrence times.

A microcomputer interface card is described, using a standard peripheral interface adapter chip, for use in multi-channel extracellular single unit recording. The design is for the Apple II. The card sends an interrupt signal to the processor whenever a pulse arrives to it, and enables the computer to read out which of 8 possible channels brought the pulse and when.

A 32 key keyboard for the HP PDMS.

The keyboard remains the primary human interface device for existing patient data management systems. The standard bedside keyboard for the Hewlett-Packard PDMS has 16 keys which are used for both numeric data entry and multiple functions, accessed by shift key combinations. We have designed and constructed a 32 key keyboard which speeds single keystroke access to all PDMS functions. The new keyboard is backwards compatible and requires no PDMS software changes. A 32 key keyboard offers many advantages for use with the HP PDMS. The device presented is backwards compatible with the vendor's keyboard and requires no software changes. This keyboard could serve as an updated functional replacement for thousands of keyboards now in use.

Individual outcome prediction models for intensive care units.

Prognostic criteria based on static analysis of group statistics do not help much in decisions to withhold or withdraw therapy from intensive care unit (ICU) patients too ill to benefit, since they do not provide adequate information on the features that distinguish non-survivors from survivors. A predictive model which uses dynamic analysis of severity scores based on physiological variables is presented here along with the results of tests of the model in 831 ICU patients. 109 patients were correctly predicted to die by the model. Of 722 whose prediction was outcome unknown, 181 died. Thus, the odds for prediction of death among non-survivors were 0.376. Since there were no false predictions of death, the estimated chance of a false prediction was 0.0055.

[Computerization of a bank of platelets with HLA phenotype and preserved at -196 degrees C]. / Informatisation d'une banque de plaquettes phénotypées HLA et conservées à -196 degrés C.

In order to complete the logistics of the unit cytapheresis, we have developed a decision helping system which rests upon the computer management of -196 degrees C cryopreserved HLA type platelets. The hardware used is a micro-computer equipped with two floppy disks and a printer. Two files have been created: namely "Product" and "Patient". Data relating to 800 platelet concentrates may be recorded on a floppy disk. The software which has been developed has several functions: 1 - The input of the parameters of a HLA type concentrate with the possibility of reservation for the given recipient; 2 - The print out of the bank's stock; 3 - The selection and the reservation of HLA matched platelets according to the recipient; 4 - The print out of concentrates allocated to each patient, it is possible to thaw out chosen platelet concentrate and a thawing report is printed out, thus enabling one to locate the concentrate in the bank. Thanks to this "aid in decision making", the management of - 196 degrees C cryopreserved HLA type platelets may be carried out. The proposed software allows an one line answer for any emergency transfusion case. Considering the recipient HLA typing the suitable best match platelet concentrates are instantly transfused or save.

On-line three-parameter data uptake, analysis, and display device for flow cytometry and other applications.

Multiparameter flow cytometric measurements are of growing interest in the study of complex features of biological cells. With state of the art instrumentation, three-parameter (3-P) data handling is relatively complicated and time consuming and the display methods are not satisfactory. As an alternative, an interactive 3-P analyzing module, Cytomic 123 is described, which displays 3-P fields during and immediately after data uptake in the form of a cubic array of 32,768 channels. The fields can be randomly rotated by hardware and software. The event frequencies in the field are primarily visualized by brightness modulation of the display dots. Additionally, the display of the field may be confined to user selected ranges of event frequencies, which may also be superposed to mixed frequency displays. A set of preprogrammed functions is available for the following tasks: (a) uptake of 3-P histograms combined with on-line control of the transducer pulses, (b) automatic uptake of a series of 2-P time correlated histograms in the cube, (c) generation and numerical evaluation of sections and projections of cube histograms, (d) interactive generation and evaluation of spatial subfields for integration, or as sorting matrix by successive erosion of section planes, or reprojection of projection windows, and (e) isometric display of sections and projections and exchange of data sets with other Cytomic modules or other data systems, especially the Cytomic 12 module, whose 2-P capabilities can be used. The module is built with low cost Z80 microprocessor eurocards. A standard oscilloscope serves as a display unit.

The QUEST system for quantitative analysis of two-dimensional gels.

The strategies and methods used by the QUEST system for two-dimensional gel analysis are described, and the performance of the system is evaluated. Radiolabeled proteins, resolved on two-dimensional gels and detected using calibrated exposures to film, are quantified in units of disintegrations per minute or as a fraction of the total protein radioactivity applied to the gel. Spot quantitation and resolution of overlapping spots is performed by two-dimensional gaussian fitting. Pattern matching is carried out for groups of gels called matchsets, and within each matchset every gel is matched to every other gel. During the matching process, spots are automatically added to each pattern at positions where unmatched spots were detected in other patterns. This results in enhanced accuracy for both spot detection and for matching. The spot fitting procedure is repeated after matching. Tests show that up to 97% of spots in each pattern can be matched and that fewer than 1% of the spots are matched inconsistently. Approximately 2000 proteins are detected from typical gels. Of these 1600 are high quality spots. Tests to measure the coefficient of variation of spot quantitation versus spot quality show that the average coefficient of variation for high quality spots is 21%. The intensities of the detected proteins range from 4 to 20,000 ppm of total protein synthesis. The QUEST analysis system has been used to build a quantitative database for the proteins of normal and transformed REF52 cells, as presented in the accompanying reports (Garrels, J., and Franza, B. R., Jr. (1989) J. Biol. Chem. 264, 5283-5298, 5299-5312).