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At least 379 records · Page 21Linked to original sources
PubMed2006

Computer systems analysis of spaceflight induced changes in left ventricular mass.

Circulatory adaptations resulting in postflight orthostasis have frequently been observed in response to space travel. It has been postulated that a decrement in left ventricular mass (LVM) found after microgravity exposure may be the central component in this cardiovascular deconditioning. However, a physiologic mechanism responsible for these changes in the myocardium has not been determined. In this study, we examined the sequential alterations in echocardiographic measured LVM from preflight to landing day and 3 days into the postflight recovery period. In a previous study in returning astronauts we found a comparative 9.1% reduction in postflight LVM that returned to preflight values by the third day of recovery. This data was further evaluated in a systems analysis approach using a well-established advanced computer model of circulatory functioning. The computer model incorporates the physiologic responses to changes in pressures, flows and hydraulics within the circulatory system as affected by gravitational forces. Myocardial muscle progression to atrophy or hypertrophy in reaction to the circulatory load conditions is also included in the model. The integrative computer analysis suggests that these variations in LVM could be explained by simple fluid shifts known to occur during spaceflight and can reverse within a few days after reentry into earth's gravity. According to model predictions, the reductions in LVM found upon exposure to microgravity are a result of a contraction of the myocardial interstitial fluid space secondary to a loss in the plasma volume. This hypothesis was additionally supported by the published ground-based study in which we followed the alterations in LVM and plasma volume in normal subjects in which hypovolemia was induced by simple dehydration. In the hypovolemic state, plasma volume was reduced in these subjects and was significantly correlated with echocardiographic measurements of LVM. Based on these experimental findings and the performance of the computer systems analysis it appears that reductions in LVM observed after spaceflight may be secondary to fluid exchanges produced by common physiologic mechanisms. Reductions in LVM observed after microgravity exposure have been previously postulated to be a central component of spaceflight-induced cardiovascular deconditioning. However, a recent study has demonstrated a return of astronauts' LVM to preflight values by the third day after landing through uncertain mechanisms. A systems analysis approach using computer simulation techniques allows for a dissection of the complex physiologic control processes and a more detailed examination of the phenomena. From the simulation studies and computer analysis it appears that microgravity induced reductions in LVM may be explained by considering physiologic fluid exchanges rather than cardiac muscle atrophy.

Adult↗
PubMed1993

[Computer systems in gastroenterologic endoscopy. An analysis of current availability on the Austrian market].

Five systems for computerized documentation (ADAM-Fujinon, ENDOBASE-Olympus, MEDASYS-Pentax, MEPAS-Fritsch & Jirak, OPTAMED-Krötlinger) are compared in their different functions: configuration of system, software, communication, structure of program, user guidance, data-protection, data back-up, patient registration, preparation for examination, terminology setup, report generation, image filing, statistic, system adjustments, costs. This paper should be a help in buying a computer-aided system. All systems fulfil the three basic requirements for a computer-aided documentation in gastrointestinal endoscopy: database, image filing, report generation. Actually none of the programs can be favoured. Peculiarities, weakness and strength of the different programs are discussed. The principle of the scoring-method in choosing a system is explained.

Austria↗
PubMed1996

Intelligent fetal heart rate computer systems in intrapartum surveillance.

The intrapartum cardiotocogram has had a disappointing impact on clinical practice. Misinterpretation of the cardiotocogram not only causes an increase in unnecessary intervention but is also implicated in a large proportion of patients with birth asphyxia and avoidable perinatal morbidity. Over the past 10-20 years, groups have attempted to develop computer systems capable of analysing the cardiotocogram but with limited success. The likely explanation is that these conventional systems analyse the cardiotocogram in isolation from clinical factors. More recently, research has focused on the use of artificial intelligence techniques which can assess the whole clinical picture to support clinical decision making during labour. The current literature is reviewed and a system that has been validated by comparison of its performance with 17 experts is described.

Cardiotocography↗
PubMed1993

Personal computer system for tracking cardiac vulnerability by complex demodulation of the T wave.

Complex demodulation of the T wave permits tracking of susceptibility to ventricular fibrillation under the clinically relevant conditions of acute myocardial ischemia and reperfusion. To facilitate the processing and to increase the applicability of the methods, we have developed algorithms and applied mathematical transformations that can be carried out with a personal computer. The program is self-contained and menu driven and transforms the data into a three-dimensional graphic display of magnitude of alternans (mV x ms), time in the cardiac cycle, and duration of the assessment. It is suitable for investigations with diverse experimental procedures such as coronary artery occlusion and release, autonomic interventions, behavioral stress testing, and drug administration. Our methodology may be employed in clinical conditions such as postmyocardial infarction. Prinzmetal's angina, and the long QT syndrome, wherein T wave alternans has been reported in body surface leads. Ultimately, T wave alternans analysis with use of the personal computer system may help guide therapeutic interventions.

Algorithms↗
PubMed2006

Evaluation of a simplified generic bi-substrate rate equation for computational systems biology.

The evaluation of a generic simplified bi-substrate enzyme kinetic equation, whose derivation is based on the assumption of equilibrium binding of substrates and products in random order, is described. This equation is much simpler than the mechanistic (ordered and ping-pong) models, in that it contains fewer parameters (that is, no K(i) values for the substrates and products). The generic equation fits data from both the ordered and the ping-pong models well over a wide range of substrate and product concentrations. In the cases where the fit is not perfect, an improved fit can be obtained by considering the rate equation for only a single set of product concentrations. Due to its relative simplicity in comparison to the mechanistic models, this equation will be useful for modelling bi-substrate reactions in computational systems biology.

Catalysis↗
PubMed2003

A helping computer system prognosing the survival of patients with Hodgkin's disease.

INTRODUCTION AND AIMS: Hodgkin's disease is an uncommon form of lymphoma occurring mainly at 15-35 years of age. Prognostic evaluation plays an important role by supplying a rational working linkage between the wide complexity of disease presentations and available therapeutic resources. Improved prognostic evaluation able to identify the likely outcome of a given patient would be of considerable clinical importance. The aim of this study was to develop and present a computer system and tools that will allow physicians to make more precise prognosis of the survival in such patients. MATERIAL AND METHODS: Several mathematical models were developed using multivariate statistical survival analyses. Data on 116 patients with Hodgkin's disease treated in the Clinic of Hematology (Plovdiv, Bulgaria) between 1974 and 2001, were collected. The patients' database consisted of general information for each patient (name initials, age, sex, date of diagnosis, etc.) as well as of specialized clinical information. RESULTS: The present system has provided different options for calculation of survival probabilities and prognosis using deterministic models for each patient. CONCLUSIONS: The use of the present system in routine practice has allowed physicians to facilitate the process of making more precise prognosis of survival. In this way, they have been able to optimize the treatment scheme and improve the quality of life of their patients.

Adolescent↗
PubMed1978

Analysis of fatty acid methyl esters by a gas--liquid chromatography--chemical ionization mass spectrometry computer system.

The technique of gas-liquid chromatography-chemical ionization mass spectrometry can easily identify trace peaks and unresolved peaks on gas-liquid chromatography, utilizing MH(+) ions of chemical ionization mass spectra. In polyunsaturated fatty acid methyl esters such as C22:5 and C22:6, the determination of molecular weights that are difficult to determine by electron impact mass spectrometry could be easily identified by chemical ionization mass spectrometry. The identification could be performed even more easily from a mass chromatogram obtained by means of a gas-liquid chromatography-chemical ionization mass spectrometry-computer system. This technique was applied to analysis of fatty acid methyl esters of triglycerides, cholesteryl esters, nonesterified fatty acids, and phospholipids obtained from normal human serum. It was observed that odd-carbon-number fatty acids contained more isomers of different types than even-carbon-number fatty acids, whether the fatty acids were saturated or unsaturated. As for the types of isomers, we presume the existence of iso, anteiso, branched, cyclic fatty acids, and, in the case of unsaturated fatty acids, positional isomers. The qualitative determination of the group of fatty acid isomers containing 20 carbon atoms was also investigated as well as the application of procedures for quantitative determination. Sensitivities for saturated fatty acids differ from those for unsaturated fatty acids of the same carbon number, and sensitivities for unsaturated fatty acids of the same carbon number differ with the number of double bonds because the amounts of MH(+) - 32 and MH(+) - 32 - 18 fragment ions formed are different.

Chromatography, Gas↗
PubMed2006

[Counting-type analog quantity and development of mutli-channel telemetering computer system for dynamic information about human vascular wall].

Counting-type analog quantity (CAQ), a new conception, is introduced in this article. CAQ possesses some features of analog quantity and digital quantity, that is to say, it has double features. By analysis, two kinds of CAQ are found: one is width-modulated countable pulse series, the other is frequency-modulated countable pulse series. Furthermore, the method of generating CAQ is described and its double feature is also proved. It is very convenient to realize single-channel or multi-channel analog-to-digital (A/D) conversion by using CAQ without utilizing present integrated A/D conversion chip. In this paper, for proving its feasibility, multi-channel telemetering computer system for dynamic information about human vascular wall,a typical example of using CAQ in medicine, is expatiated. The typical example clearly indicates: not only the method for application of CAQ is simple and viable, but also the application of CAQ is very wide.

Analog-Digital Conversion↗
PubMed1975

Westminster hospital computer system User attitudes.

Development of computer-assisted patient monitoring began at Westminster Hospital in early 1971. The system handles fluid balance measurements from data input to the system by keyboards, and automatically monitors cardiovascular measurements made by standard bedside monitors. Various graphical outputs are available on visual displays at the bedside to assist in the care of the patients, and as hard copy to replace the "traditional" nurses charts. The system was designed to assist the nurses in their daily tasks, and much of its initial success is believed to be due to the "user oriented" design philosophy.

Adult↗