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A microcomputer program to analyze the CD spectrum of proteins and nucleic acids--use of LOTUS 1-2-3 spread sheet.

A user friendly interactive computer program, CIRDIC, is developed which calculates the molar ellipticity and molar circular dichroic absorption coefficients from the CD spectrum. This, in combination with LOTUS 1-2-3 spread sheet, will give the spectra of above parameters vs wavelength. The code is implemented in MicroSoft FORTRAN 77 which runs on any IBM compatible PC under MSDOS environment.

Algorithms↗

A dedicated microcomputer-based instrument for interval analysis of multicomponent wave forms in single fibre EMG.

We have developed a self-contained microprocessor-based instrument compatible with conventional EMG equipment for the analysis of multicomponent SFEMG wave forms suitable for single operator use. Intervals between 4 components of a MUAP can be analysed using 3 types of threshold or window triggers. The amplitude, duration and polarity of each of these triggers can be varied independently. The instrument is portable and useful in the clinical setting.

Computers↗

Jittermeter--a microcomputer-based system for single fibre electromyography.

In single fibre electromyography (SFEMG) an exact measurement and computation of a number of time parameters is required. This paper describes a low-cost microprocessor-based measurement system for SFEMG data acquisition, computation of the parameters and display, as an alternative to a general purpose-computer based system. Time measurement is performed at dual resolution: 0.1 microsecond and 0.1 msec. Erroneous data due to disturbing voltages are automatically eliminated. A variety of SFEMG applications is covered by 3 basic modes of data handling. The microprocessor unit is based on the 6800 family and contains 3K of program memory, input-output modules and 4K data memory. The instructions are entered through a keyboard and output is provided by an LED display, line-printer and X-Y storage display.

Action Potentials↗

TIBIAS--a microcomputer-based analysis system for isoelectric focusing and electrophoretic patterns.

A program is described for a computer-aided analysis system for isoelectric focusing (IEF) patterns. This system is primarily aimed at comparing and statistically analyzing large numbers of one-dimensional electrofocusing patterns in the search for specific tumor markers in pancreatic ductal secretions. It is designed to collect raw densitometric data, allow interactive processing, matching and statistical tests, and prepare high-quality plots of data at various stages.

Computers↗

[Method of file sorting for mini- and microcomputers].

The authors describe a new sorting method of files which belongs to the class of direct-addressing sorting methods. It makes use of a variant of the classical technique of 'virtual memory'. It is particularly well suited to mini- and micro-computers which have a small core memory (32 K words, for example) and are fitted with a direct-access peripheral device, such as a disc unit. When the file to be sorted is medium-sized (some thousand records), the running of the program essentially occurs inside the core memory and consequently, the method becomes very fast. This is very important because most medical files handled in our laboratory are in this category. However, the method is also suitable for big computers and large files; its implementation is easy. It does not require any magnetic tape unit, and it seems to us to be one of the fastest methods available.

Computers↗

Computerized drug therapy: application of the hand-held microcomputer to dosage regimen design.

For many drugs estimation of a safe and effective dosage regimen is difficult. Typically these drugs exhibit optimal therapeutic activity when drug concentrations in the blood are maintained within narrow limits and considerable intersubject variability exists in their rate of elimination from the body. Computer programs have been written to estimate the size and frequency of dose administration necessary to achieve therapeutic drug concentrations in the blood. The programs utilize pharmacokinetic equations and information on the individual patient's physiologic (e.g., age, weight, sex) and pathologic (e.g., existence of liver or renal disease) status. The drugs studied were gentamicin, theophylline, digoxin, phenytoin and warfarin. The programs were written using the hand-held TRS 80 Pocket Computer with an 8K memory module. These programs have been in use for 3 years and are currently involved in clinical consults approx. 100 times a month.

Computers↗

A microcomputer-based system for data acquisition and analysis of step-like current jumps due to the opening of single ionic channels in model membranes.

At the cell surface, passive transport is controlled by membrane proteins forming hydrophilic pores (or channels) which span the hydrophobic core of the lipid bilayer. Gating mechanisms determine the occurrence of very small and fast step-like current jumps. We developed an intelligent system to acquire and to analyze signals due to the opening and closing of ionic single channels. A specific algorithm allows us to recognize channel current transitions and to discard false events due to noise peaks or to unwelcome fluctuations of the signal. Statistics of the single channel amplitude and mean life-time can be performed. We report the results obtained from analyzing the characteristics of the gramicidin A single channel in phosphatidylserine model membranes. Mean current values of 2.08 +/- 0.01 pA and life-times of 101 +/- 3 ms. were measured at 100mV applied potentials in KC1 100mM solution.

Biological Transport, Active↗

Microcomputer simulation of antigen-antibody binding at a fixed antigen/antibody ratio.

Computer simulation techniques were used to define the theoretical nature of the reaction of antigen with antibody at a constant degree of antigen excess. The simulation studies show that binding curves obtained under these conditions have unique features which are determined by antibody affinity, affinity heterogeneity and the concentrations of antigen and antibody. When analyzed by non-linear least squares regression these curves can be used to determine the affinity of antibody in homogeneous and heterogeneous systems.

Antibody Affinity↗

Reference master: a microcomputer-based storage and retrieval system for bibliographic references.

A complete system for housekeeping and retrieval of bibliographic references managing individual reprint collections is described. By the use of special hardware and individual data base software even large reprint collections in the range up to 65,000 papers are handled economically. A fast 8-bit microprocessor (HD 64180) in combination with a Winchester hard disk drive serves as the basis for rapid access to the desired information. An efficient string search algorithm written in assembly language guarantees a fast operation with a search speed of more than 6,000 entries/minute. The system cannot only prepare reference lists and reference files, but also incorporates an editor and maintains the control whether reprints are already on file or requested. The implementation of back-up schemes assure against data losses. Using a state of the art design single board computer and the most recent mass storage device technology, the system is as well small and cost effective, and thus suitable for personal use. In addition, some general questions and pitfalls concerning the management of scientific literature collections are touched upon.

Bibliographies as Topic↗

The use of a microcomputer to analyse differences between histograms derived from flow cytofluorimetric measurements.

Computer programs which aid the interpretation of histograms of fluorescence intensity obtained by flow cytofluorimetry are described. The methods employed have high reproducibility when used to estimate the proportion of cells contained in a subset of the population which is distinguishable by some degree of enhancement of fluorescence intensity, e.g. the lymphocyte subset in the peripheral blood mononuclear cells stained immunocytochemically with a monoclonal antibody, or for detection of those cells that have undergone activation by demonstrating an increase in cellular RNA after stochiometric staining with acridine orange. The influence of inter-observer variability and of extraneous fluorescence spikes caused by cell culture debris has been investigated, and guidelines are set out for the use of the method. The method can be used efficiently by relatively unskilled operators to obtain highly reproducible results.

Adult↗

A simulation support system for solving large physiological models on microcomputers.

Although physiological modeling and computer simulation have become useful research tools to test new scientific theories and to design and analyze laboratory experiments, developing a new model can be a tedious process because the investigator must often write very complex and specific routines for data input and output. To facilitate the design of new models (as well as the use of existing models), we have developed MODSIM, a FORTRAN-based simulation support system for the IBM PC computer than can accommodate very large dynamic models having up to several thousand equations. It provides the investigator with utilities for continuous on-line graphical and/or tabular output, as well as facilities for dynamic interaction with the model. The user must only supply a model as a list of mathematical equations written in FORTRAN, along with the initial values of the model variables and parameters. The model is precompiled, compiled, and then linked to the MODSIM utilities. Without further programming, the user can then solve the model, select variables for graphical output, and stop the model at any time to analyze the data or to change a parameter before resuming the simulation. This simulation system makes it very easy to develop new models that actively interact with the experimental research of the investigator.

Computer Simulation↗

Teaching field potentials: a microcomputer simulation of the nerve action potential in a bidimensional conductor.

A computer simulation of the extracellular field potential recording of nerve activity is presented. An experimental setup composed of an oscilloscope, a nerve, a conductive surface, and a recording electrode is graphically simulated. The user may study the influence of the position of the recording electrode and of certain nerve properties (membrane potential, velocity of conduction and action potential duration), on the action potential shape. The different waves which constitute the action potential may be analyzed and their peak values plotted as a function of the independent variable (e.g. electrode distance from the nerve). Three-dimensional plots of a set of action potentials as a function of the independent variable may also be obtained. The stimulation allows the user to study the basic factors which determine the configuration of an extracellularly recorded compound nerve action potential.

Action Potentials↗

Osmosis: a microcomputer laboratory teacher.

A computer simulation of osmotic processes has been developed. Several experimental setups are graphically simulated and may be freely selected by the user. The simulation analyzes the basic factors which determine the osmotic pressure and volume flow of a solution (e.g. concentration, temperature, activity coefficient, Staverman's coefficient and external pressure). The program was written in Turbo Pascal to operate in IBM-PCs or compatibles. High quality graphical display of results maintains the students' interest. A user's guide and continuous help for the available options simplify its use. Computer simulation seems to be a very well suited aid for teaching osmotic phenomena, improving both theoretical knowledge and the ability of the students to empirically demonstrate some of the basic laws of osmotic phenomena.

Animals↗