Least-squares estimation of enzyme parameters

The estimation of the enzyme parameters K_m and V_max from initial velocity data, or of analogous parameters in binding or transport experiments may be accomplished by transformation of the data, or by a direct weighted least-squares fit. Although the latter makes better use of the data, the method is complex and may be sensitive to initial parameter estimates. We develop a method which reduces the problem to finding the zero of a continuous function of a single variable.     

Computer analysis of bowel sounds

An automatic method of analysis of bowel sound recordings has been developed. A PDP8/I computer, equipped with DECtape and interfaced with a TR48 analog computer was used for the analysis. It was found that the probability of a sound occurring followed a law similar to that of Poisson's phenomenon. Mean energy, sound duration and silence duration in the postmeal situation were respectively, 0·1589 V R.M.S., 4·5 msec, and 31·7 msec. No frequency exceeded 3000 Hz. This method of analysis was applied to experimental situations to study the importance of various parameters influencing the genesis of bowel sounds.     

An Apple IIE microcomputer program for multiple non-independent comparisons by the Scheffe's test

When more than two groups of observations from the same set of experimental data are compared and pairwise tested for equality of their means, appropriate statistical treatment of the data is required. The overall variation in the set of data must be considered, and also the statistical non-independence of each pairwise comparison must be taken into account. We describe a simple Apple IIE microcomputer program that applies the Scheffe's test for multiple comparisons. A numerical example and a sample output of this program are also included. The listing of the program is reported in the Appendix.     

A computer model for analysis of fluid resuscitation

Injuries involving massive blood loss, such as burns, combat wounds, and injuries resulting from car accidents, require fluid resuscitation. The risk involved in fluid therapy is overloading of the circulation, resulting in pulmonary edema which can lead to death. The risk of pulmonary edema may be eliminated by proper determination of maximal infusion volume and rate. Reabsorption of fluid from the extravascular compartment and infusion of fluid following blood loss results in reduction of the hematocrit. This is accompanied by an increase in the heart's preload and afterload. Coronary driving pressure and flow increase due to increased volume. However, because of the reduced hematocrit this increase in coronary flow may not be sufficient to compensate the myocardium, in terms of oxygen supply, for the increase in oxygen consumption. A model of the cardiovascular system, including an extravascular compartment, was designed to analyze the effects of fluid infusion on hemodynamic variables, cardiac oxygen balance, and the redistribution of fluid between intravascular and extravascular compartments. The results indicate that edema is not the only possible adverse effect of overloading the cardiovascular system with fluids. The simulation demonstrated that in certain cases the heart's oxygen balance can become negative. Limiting the rate of infusion can reduce this risk.     

Analog model of kinetics of calcium in healthy subjects during alimentary Ca absorption

An analog model of the kinetics of calcium in the organism was prepared focused on short-term changes which take place during the alimentary Ca absorption. The model is an attempt to describe mathematically the movement of Ca in the organism under conditions in which the Ca homeostasis and steady state of Ca kinetics are temporarily impaired.     

The evaluation of mass densities of the human body in vivi from CT Scans

An experimental method, using the CT Scanner, has been developed to evaluate the mass densities of the human body in vivo. This method iis based on theories used in computerized tomography: the concept of average effective energy (AEE), the Fourier Convolution Method in picture reconstruction, and the relationship between the numerical values of a material in a CT scan and the properties of the material. Using this method, various mass densities both of plastics obtained from phantom scans and also of tissues from patient scans were tabulated. The results compared very favorably to known values.     

Pocket computer program for fitting the Michaelis-Menten equation

This paper presents a program written for the Radio Shack TRS-80 or the Sharp PC 1211 pocket computers for fitting the Michaelis-Menten equation to experimental data by a non-linear regression analysis. The program determines the kinetic parameters Km and Vm, their standard errors and the residual standard error. In addition it performs a simulation of a kinetic experiment using the parameter values previously determined.     

Routines for calculating the first derivative of a function by numerical methods

Three methods for calculating, numerically, the first derivative of a function have been investigated. First, the three methods were compared for accuracy and time of execution using a step length of 10⁻⁶. Secondly, the accuracy of the best method was determined at different step lengths, 10⁻⁴–10⁻¹². First derivatives, ∂y/∂x, were calculated for 10 functions, y = f(x,p), common in Biochemistry, at 10 values of x, and the values compared with those obtained analytically.

The best method (i.e. the most accurate with the shortest time of execution) was not the one currently used in general purpose non-linear regression programs.     

Real-time analysis of EEG using Walsh transforms

Analysis of electroencephalogram (EEG) signals has been an area of considerable interest since the advent of inexpensive minicomputers in the mid to late 1960's. One of the major drawbacks to EEG analysis has been the inability to handle multiple demands in real-time. This paper presents a reasonable alternative to traditional Fourier analysis by proposing the use of the Fast Walsh Transform. Such problems as phase sensitivity and general acceptability of the Walsh power spectrum are discussed.     

Sequential iteration of Bayesian formula by pocket calculator and its use in clinical routine

By the Bayesian formula, a posteriori probabilities of medical diagnoses are calculated from their a priori probabilities and from the conditional probabilities of test results. This paper describes a short program of the Bayesian formula for a pocket calculator which considers up to 21 differential diagnoses and an unlimited number of tests.     

A system for the retrieval of family structured information

The Linkage Automated Investigative Device (LAID) is a system for the storage, retrieval, and display of family structured information. The LAID data base is designed in terms of nuclear families such that, given any individual, those persons of any specified relationship can be quickly located. The user may specifiy criteria in terms of many data categories to be met by the individual being sought as well as criteria to be met by his relatives.

LAID retrieval requests are written in an easily used yet highly flexible language and executed on a PDP 11/45 computer under the DOS V8 or RSTS V6 operating system.     

New standards for devices used for the measurement of human body temperature

Significant changes in recording of human body temperature have been taking place worldwide in recent years. The clinical thermometer introduced in the mid-19th century by Wunderlich has been replaced by digital thermometers or radiometer devices for recording tympanic membrane temperature. More recently the use of infrared thermal imaging for fever screening has become more widespread following the SARS infection, and particularly during the pandemic H1N1 outbreak. Important new standards that have now reached international acceptance will affect clinical and fever screening applications. This paper draws attention to these new standard documents. They are designed to improve the standardization of both performance and practical use of these key techniques in clinical medicine, especially necessary in a pandemic influenza situation.     

Application of the “Hopscotch” algorithm for solving the heat flow equation for the human body

The application of an algorithm, called “Hopscotch”, is described for solving the heat equation in a model of the human body. Most digital computer integrating techniques are not explicit and, therefore, require very small time increments for a stable convergent solution. This algorithm is stable and very efficient in spite of the non-linear characteristics of the model.     

Low cost implementation of an epidemic model

An epidemic model consisting of 3 coupled non-linear differential equations was programmed on an inexpensive pocket calculator to run fast enough and accurate enough for demonstration to, or exploration by, students.     

The effects of lactation and ambient temperature on the body temperature of female Norway rats

Norway rat dams were placed in an ambient temperature of 4°C, 22°C, or 28°C. Body temperatures were recorded over a two hour period on three days; each female was observed on Day 4 and Day 10 of lactation and three days after lactation was stopped. Body temperatures were initially higher during lactation than after lactation had stopped. Dams were less able to maintain their body temperatures in the 28°C ambience on Day 4 of lactation than after lactation, and on Day 10 of lactation, were even less able to maintain their body temperatures than on Day 4. During lactation, dams were able to maintain and even increase their body temperatures in the 4°C ambience. The data support the hypothesis that the acute hyperthermia encountered by rat dams during contact with their litters may be due to a physical restriction on maternal heat loss.     

3-D computer model of subcortical structures of human brain

Three-dimensional computer model of thalamus and adjacent formations of human brain has been elaborated on the basis of sagittal slices from the Schaltenbrand-Bailey stereotactic atlas. The model includes 120 morphologically distinguishable structures and consists of more than 16 million points (volume elements) each of them being associated with the particular structure in the brain. The model is stored in the long-term computer memory. A special software has been developed to facilitate utilizing the model obtained. The software facilitates synthesizing arbitrary cross-sections through the brain and provides the correspondence between the stereotactic coordinates of any point and its position on the screen of monitor. The coordinates of the point in the system of stereotactic atlas and the name of the structure, the point belongs to, are also supplied. It is also possible to get magnified images of cross-sections and to get isometrical images. The system enables the neurosurgeon to improve the planning and execution of stereotactic operations, and will also be helpful for education.     

Algorithm for the national allocation of hearts and heart-lungs

The algorithm used for the equitable allocation of hearts and heart-lungs to potential recipients in the United States is presented. A brief history of the development of the algorithm is followed by discussion of the input criteria and implementation. The current computer system is discussed with emphasis on access by organ procurement personnel.     

Computer methodology for simulation and prediction of alloimmune responses: Expected antibody specificities

The methodology presented here was developed for simulating planned alloimmunization results, with regard to the type and number of expected antibody specificities. The computer program designed for this purpose was adapted to an immunogenetic model using Boolean algebra. It was written to help immunogeneticists avoid handling routine data preceding selection of donor-recipient pairs, specially concerning blood type alloimmunizations in animals: all of the donor-recipient combinations and the expected antibody specificities (their limit number being specified in each particular immunization program) are provided in the print-out.     

AAQUANT: A computer program for quantitative amino acid analysis of proteins and peptides

Quantitative amino acid analysis is an important tool used in the characterization and structural determination of peptides and proteins. A new computer program, AAQUANT, has been developed specifically to aid researchers in analyzing amino acid composition data. AAQUANT calculates amino acid recoveries, including 95% confidence intervals, following acid hydrolysis of peptides and proteins, and also includes useful routines to locate regions of a specified amino acid composition in known protein sequences, compute amino acid composition reports of known protein sequences, generate proteolytic digestion maps of proteins, and create and edit protein sequence data files. This report describes the AAQUANT routines, and demonstrates the use of the program.