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At least 523 records · Page 29Linked to original sources
PubMed1986

A pulse generating and data recording system based on the microcomputer PDP 11/23.

A widely applicable measuring system, especially suited for all types of 'voltage-clamp' (including 'patch-clamp') experiments, is presented. It is mainly based on commercially available hardware and software components. All interfacing with the analog world takes place on the front panel of the microcomputer box. Synchronization of pulse generation with data acquisition and other control actions take advantage of the four upper bits not used by the digital-to-analog converter during direct memory access transfer.

Computer Systems↗
PubMed1986

A microcomputer program for individualizing factor VIII dosage in hemophilia patients undergoing major surgery.

A pharmacokinetic program that allows individualization of Factor VIII dosage regiments in hemophilia patients undergoing major surgery is described. The program, which is designed for the IBM PC microcomputer and compatible machines, is based upon the one-compartment open model with instantaneous input. In the framework of such a pharmacokinetic model, it is assumed that the elimination of Factor VIII is faster during the early post-operative period and that it decreases progressively over the following days. Since Factor VIII half-life is dependent on the time elapsed since the operation (short half-life values during the early post-operative period, longer half-life values thereafter), the pharmacokinetic model is a nonlinear one. A first-order 'variation' rate constant is used to describe the prolongation of Factor VIII half-life from the initial value immediately after surgery to the final value achieved several days later. Individualized estimation of the patient's kinetic parameters (initial half-life, 'variation' rate constant and volume of distribution) is performed through the Bayesian method. Therefore, for such estimation the program exploits the Factor VIII plasma levels measured in the individual patient as well as the population pharmacokinetic data of Factor VIII. After estimating the individual's Bayesian parameters, the program predicts the dosage regimen that will elicit the desired time-course of Factor VIII plasma levels. If requested, the program is able to calculate the least-squares estimates for the parameters of the pharmacokinetic model and dosage prediction can also be made on the basis of such estimates. The least-squares estimates are useful for calculating population pharmacokinetic parameters according to the Standard Two-Stage method. Some examples of clinical use of the program are presented.

Computers↗
PubMed1986

Development of electrocardiographic teaching materials using an MC68000-based, interactive graphics microcomputer.

Interactive computer-graphics methods of computer-aided design (CAD) have been applied to problems in physical science and industry for several years; however, at the present time CAD methods have not been widely used to solve similar problems in medical education. Electrocardiogram waveform fabrication for the production of teaching materials seemed to be a well-defined area for CAD application. The availability of inexpensive, 16/32 bit word, MC68000-based microcomputers (e.g. Apple, Macintosh) and interactive graphics software (e.g. MacPaint and MacDraw) seemed to provide the necessary tools to make this application. This paper describes the authors' initial experience (from June 1984 to March 1985) in developing and employing an interactive computer graphics routine to produce ECG teaching materials.

Cardiovascular Diseases↗
PubMed1987

Fast microcomputer-based multipurpose filtering routine.

In order to perform high-speed digital signal filtering or differentiating at reduced costs, we developed a 68000 assembler routine which runs on a 68000 coprocessor card in an Apple II computer. It achieves a remarkable saving of computational time and may also be used directly with any 68000-based microcomputer.

Microcomputers↗
PubMed1987

Microcomputer-based programs for calculating mean and variance residence time by the method of prospective areas.

A published package of microcomputer-based pharmacokinetic programs has been expanded to include programs to calculate mean and variance above the residence time (MRT and VRT) using the method of prospective areas. Three programs, one for plasma concentration time data, one for urinary excretion data, and one for in-vitro dissolution data, are available. All programs were tested with the data obtained from original articles or from simulated theoretical data. These programs were written in a modular fashion in such a way that they form an integrated software package. In conjunction with the programs previously developed, the user can choose/select how extensively the data are to be analyzed without reentry of data. This is particularly important since proper pharmacokinetic data analysis can only be made by using different calculations with different assumptions. Graphic display and linear regression subroutines are included in each module to simplify operation for the user. The modular design also facilitates modifications, upkeep, and accommodation to new methods of calculation.

Computers↗
PubMedDate not supplied

Microcomputer BASIC program to calculate the probability of graft and patient survival in renal transplantation.

A BASIC program was written for the estimation of the probability of graft and patient survival in renal transplantation on a microcomputer. The program was developed for single-centre statistics in renal transplant units and uses the life table and logrank test method for calculation of survival rates. The program structure is described in detail to make rewriting easy. It is hoped that this report will help transplant centres without access to main-frame computers to develop user-friendly software running on their own computer.

Actuarial Analysis↗
PubMedDate not supplied

Microcomputer program for interactions in drug elimination in the rat.

In modern medicine patients often require multiple drug therapy. Such therapy can be modeled by a physiological flow model using interlinked differential equations to represent the differential rates of delivery and uptake of a drug by organs. Included in the model are the sites of action, toxicity, elimination and drug binding. A menu-driven computer program for this model was developed in FORTRAN 77 for execution on a microcomputer. The program computes the rate of uptake and concentration of drug in key tissues as a function of time. Drug administration can be modeled for bolus injection with up to 10 repeats and/or for continuous infusion of the drug. The drugs warfarin and adriamycin are used as illustrative examples. The program can handle multifactorial problems such as acute and chronic competitive elimination interactions, liver damage, and features of aging such as reduced drug binding and organ function. The computed results can be printed numerically or displayed graphically, either on a screen terminal or as hard copy. The results of several simulations may be cross-plotted for studies involving parametric changes such as would occur in multiple pathology and aging.

Animals↗
PubMedDate not supplied

Implementation of multiuser MUMPS language database systems on microcomputers.

This paper outlines the problems involved in implementing multiuser MUMPS language database systems on microcomputers and discusses practical solutions. Examples of the techniques presented are derived from experience with a large database system, PTIN/PTQ/MEDAR, running on an IBM AT with up to 10 separate users.

Computer Systems↗
PubMedDate not supplied

A multiuser MUMPS language patient/physician scheduling system for microcomputers.

A microcomputer based patient and physician scheduling system is described that accommodates the special needs unique to residency training programs. Appointments are scheduled automatically according to the type of problems the patient brings to the office as well as the differing time requirements of attending physicians and residents at various levels of training.

Appointments and Schedules↗
PubMed1989

A microcomputer-based sleep stage analyzer.

A microcomputer-based sleep stage analysis system for laboratory use is described. Rapid spectral analysis of the electroencephalogram (EEG) is achieved through hardware; subsequent analysis, including determination of the relative power in user-defined EEG frequency bands is provided through software. A decision matrix, based on standard sleep state analysis criteria, enables these spectral data, in conjunction with integrated electromyogram (EMG) power, to determine sleep stages. The system has been configured here to quantify standard sleep stages, but the algorithm can also identify, and provide information about, EEG states which are not easily classified according to earlier criteria used for visual classification of polygraphic records. This low-cost, user-friendly system thus achieves flexible, quantitative analysis of EEG and EMG signals.

Animals↗
PubMed1989

A microcomputer-based clinical trial database incorporated with an 'audit trail' for correction process.

Multicenter clinical trials usually involve several hundred research variables with tens of thousands of records and require mainframe computers for processing. Because of recent advances in hardware and software, it has become possible to support data management and statistical analysis for a complex research project totally on a microcomputer. The Veterans Administration Cooperative Studies Program Coordinating Center (CSPCC) in Hines, IL, U.S.A. has successfully implemented three studies employing the SIR/PC Database Management System (DBMS) on an IBM PC AT. The CSPCC DBMS was designed with a method of verifying data and of updating the database, that leaves a more detailed 'audit trial' of the original data and subsequent modifications than provided by the SIR audit trail facility. Data validation can be done at any time throughout the study to facilitate error identification as early as possible in the data handling process. DBMS operation and maintenance are automated by a system of menus. The utility programs are prestored in a procedure file to optimize performance. The simple design speeds implementation and also reduces the cost of development.

Clinical Trials as Topic↗
PubMed1989

Experimental data acquisition and manipulation by microcomputer.

To improve experiment management, we developed a microcomputer system which automatically displays, collects, manipulates and stores data in real-time. Upon completion of all experiments, it automatically performs statistical analysis, prints graphs and stores the results. The components required to accomplish these tasks include: (1) a microprocessor and visual monitor; (2) transducers, each with preamplifier, filter and amplifier; (3) couplers from each amplifier to the computer; (4) software to direct display, manipulation, statistical analysis and storage of data; and (5) hardware to allow real-time graphic and hard copy display. The resulting system allows sampling rates up to 300 Hz and accuracy of 0.20% full scale, 0-200 mm Hg. It provides great flexibility, efficiency and reliability in data management, and thereby facilitates the organization and completion of research protocols. It simplicity of design and operation makes it easy to use, and it is extremely cost effective. We present a method of laboratory microcomputerization as a practical alternative for management of physiological experimentation.

Analog-Digital Conversion↗
PubMed1990

Microcomputer-assisted multivariate survival data analysis using Cox's proportional hazards regression model.

We describe a microcomputer program (COXSURV) for proportional hazards multiple regression analysis of survival and other failure-time data generated in clinical trials and in retrospective clinical epidemiology studies. COXSURV is menu-driven and has powerful variable factoring and data exploratory capabilities for multivariate modeling. A batch mode allows automatic uni- or multivariate analyses for confounder summarization. Model selection for predictive purposes is possible through a step-up algorithm. The partial likelihood method used in the program allows the use of either discrete or continuous time scales by treating tied uncensored observations by either the exact method or by a robust approximation method. The program calculates most standard model fitting statistics for either overall or stratified analyses and uses data layout files compatible with those of other related epidemiologic analysis software.

Algorithms↗
PubMed1990

Parallelism test on microcomputers for statistically comparing regression lines of bivariate data sets.

Biomedical research is frequently confronted with regression lines that directionally describe the trend of phenomena, each one represented by a set of correlated x and y data. There could be a need to verify whether the regressions lines of two (or more) phenomena are statistically comparable in their slopes and intercepts, in order to draw conclusions about the similarity or dissimilarity of the conditions under scrutiny. The parallelism test the principles and methodology of which are presented here addresses this problem. A program for microcomputers is supplied as a non-profit software that can be freely shared on the understanding that the copyright belongs to the authors of this article.

Analysis of Variance↗
PubMed1990

A versatile implementation of the Gauss-Newton minimization algorithm using MATLAB for Macintosh microcomputers.

The present report describes a weighted nonlinear least-squares minimization routine for fitting a wide variety of functions nonlinear in the parameters. The minimization routine is implemented in MacMATLAB, the Macintosh microcomputer version of MATLAB, an interactive program for scientific numeric calculations. Our algorithm makes use of a subroutine that estimates the required derivatives numerically, avoiding the need to differentiate the function under study analytically. We have also implemented two specific subroutines to integrate ordinary differential equations numerically. Therefore, in principle, any kind of nonlinear function can be fitted to a given set of data. The program only requires that the user writes the appropriate equation in a specific subroutine, thus relieving one from knowing and using any 'low-level' code. Other features of the program are: (a) the possibility of using weight to correct for nonuniformity of variance by flexible specification of the error structure; (b) the possibility of checking the parameter values and the residual variance at each iteration; and (c) by the use of the graphic capabilities of MacMATLAB, the possibility of following the improvement of the fitting graphically. One example of nonlinear functions and one example of linear differential equation together with their respective 'function file' and illustrative data are presented to demonstrate the flexibility of our approach and the power of the method used.

Algorithms↗
PubMed1991

A microcomputer-based interactive cough sound analysis system.

The occurrence and nature of cough sounds, especially those occurring in asthma in young children, is of considerable interest to workers in paediatrics and general practice. To facilitate our research into the characteristics of such sounds, we have developed a microcomputer-based analysis system, which we call COFF. In this paper we discuss the design and implementation of the system, emphasising its user-friendly, interactive features, and the manner in which it efficiently manages the large amounts of data that research into sounds incurs. We illustrate the operation of the system with examples of spectrograms computed from cough sounds recorded simultaneously at the mouth and through the chest wall.

Asthma↗
PubMed1991

Fluxplus, a microcomputer program for interactive calculation of 'in vitro' solute fluxes, uptakes and accumulations in studies of intestinal transport.

A new microcomputer program for interactive comparisons, analysis and calculation of in vitro solute transepithelial fluxes and nutrient uptakes and accumulations by intestinal tissues is described. The program is written in Microsoft GWBASIC for the widely distributed IBM-PC. Flux, uptake and accumulation values are obtained by computation from initial sequential data files and stored in sequential or random-orgaized files, depending on the specific process. Computed unidirectional fluxes are saved together with their associate electrical variables. The program calculates univariate statistics for unidirectional and net fluxes, and allows comparisons between selected groups of experiments by using the Student's t-test. An homocedasticity test is also provided. Active uptake or accumulations of solutes are calculated by substracting the predicted diffusive values at a determined concentration to total uptake or accumulation and from this, kinetic parameters are computed. The program was designed to be user-friendly and includes several functions to permit the user to manage and examine stored data. Examples of outputs illustrate applications of the program.

Animals↗