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PubMed1990

Use of a piezoelectric film sensor for monitoring vascular grafts.

Detection of failing arterial reconstructions requires intensive surveillance by frequent physical examination and noninvasive laboratory testing. However, many grafts fail during the intervals between these examinations. For this reason, we have developed an implantable miniaturized piezoelectric flow detection device whose function can be monitored externally by radiotransmission across the skin. Sensors were constructed from ultrathin polyvinylidene fluoride (PVF2) with piezoelectric activity and attached with silicone fixative to 6-mm polytetrafluoroethylene grafts. Ten of these grafts were placed in mongrel dogs as iliofemoral bypasses. Real time data were acquired from the sensors at a rate of 200 Hz, using a DATAQ A/D data acquisition board and CODAS data acquisition software, while simultaneous blood flow (using an electromagnetic flowmeter) and intraluminal pressure were processed by using separate channels of the same data acquisition board. The data were stored on computer storage media and analyzed by the ASYST software, which allows simultaneous signal curves to be compared using regression analysis. In the resting state, the mean blood flow was 123 +/- 16 mL and the mean intraluminal pressure was 124/78 mm Hg, and there was perfect correlation between the PVF2 sensor and the flowmeter and between the sensor and the intraluminal pressure (correlation coefficient, r greater than or equal to 0.99 and r greater than or equal to 0.93, respectively). A tourniquet was applied to the iliac artery proximal to the graft to reduce the flow to approximately half of the resting state (mean flow after tourniquet: 66 +/- 6 mL/minute). Signal tracings from the three sources showed a remarkable similarity with a very high correlation coefficient (r greater than or equal to 0.99 between sensor and flowmeter and r greater than or equal to 0.92 between sensor and the pressure signal). These preliminary results show that the sensors made from low-profile and low-mass PVF2 material have the potential of being implanted around grafts for long-term, continuous monitoring of graft function. Further studies involving long-term implantation to assess the effect of tissue ingrowth and loss of compliance are necessary before this device can be used clinically.

Animals↗

PubMed1987

A simple electronic device and computer interface system for monitoring chewing behavior of stall-fed ruminant animals.

A simple and low cost electronic switching device interfaced to a microcomputer was developed and utilized to monitor the chewing behavior of stall-fed cattle. The system transforms jaw movements directly into binary notation. The device is attached to a halter and consists of two contact points inserted into a piece of rubber tubing. Elongation of the rubber tubing by the movements of the lower jaw breaks the electrical circuit between the contact points. Every break in the circuit is recorded as a chew by the time-clock-equipped microcomputer, which records animal and time of each chew (nearest second). Data are stored automatically at the end of every hour and later transferred to diskettes for permanent storage and future processing. Use of an interface card allows simultaneous monitoring of up to eight animals. A program was written to separate chewing during eating from chewing during rumination. The system has been used successfully for approximately 2500 steer-h and could be easily adapted to most species of ruminants.

Animals↗

PubMed1987

Electronic imaging system for direct and rapid quantitation of fluorescence from electrophoretic gels: application to ethidium bromide-stained DNA.

We have built an electronic imaging system based on a modified charge-coupled-device television camera that directly quantitates the distribution of fluorescence from electrophoretic gels, chromatograms, and other stationary sources. Exposure times can exceed 1 min. Unlike the photographic system that it replaces, the response of the camera is directly proportional to the intensity of incident fluorescence, and image data are digitized and stored in computer memory ready for analysis immediately upon completion of an exposure. We describe procedures for the display, normalization, and archival storage of image data and programs that use images of ethidium bromide-stained DNA in alkaline agarose gels to quantitate single-strand breaks in DNA.

DNA↗

PubMed1985

Toxicology information systems: a historical perspective.

Toxicology information systems have evolved swiftly from early, library-based bibliographic tools to advanced packages utilizing sophisticated computer and telecommunication technologies. These systems have evolved concurrently with the rapid expansion of the science of toxicology itself. Bibliographic files such as TOXLINE represent first attempts to handle the toxicology literature through on-line retrieval. Subsequent approaches applied the use of computers to provide literature-derived data, as in TDB or RTECS, or to capture data directly in the laboratory. Societal concerns about hazardous substances, manifested in legislation and regulations, have been responsible for the creation of many computerized systems. Advanced, integrated information management systems are being explored as a method of accessing a large number of independently maintained toxicology databases. Changes in information technologies such as the trend toward microcomputers and novel high-density storage devices will affect the future of toxicology information systems as will impending developments in toxicology itself related to biotechnology, analytical methodology, and alternatives to whole animal testing.

History, 20th Century↗

PubMedDate not supplied

A new instrument for continuous recording of the evoked compound electromyogram in the clinical setting.

To study neuromuscular transmission, observation of the evoked compound electromyogram (EMG) has important advantages over observation of the evoked mechanical muscle contraction. Technically, however, recording of the evoked compound EMG, especially in continuous study of several hours duration, has been difficult. Investigators have employed various complicated systems, including tape recording, photorecording, and photographing for such purposes. The authors have applied modern computer technology to construction of an EMG analyzer which enables handling the evoked EMG even more easily than the evoked mechanical contraction. The principle involves digital dissection, storage with memory, readout with time expansion, and analog reconstruction of the compound EMG. The signal can be recorded with ease by use of any suitable hot-stylus or ink-writing oscillographic recorder. Both the waveform and the amplitutde of the EMG can be on-line recorded. The cost compares favorably with comparable devices for similar studies.

Electromyography↗

PubMed1990

[Video technique for documentation of endoscopic findings].

We present a method for recording medical findings using a single chip camera, monitor, storage device and a graphic printer. Statistical and functional findings can quickly be determined and recorded by instant graphics. These screen prints are repeatedly accessible at any time for medical records. This simplifies the diagnostic counselling of the patient as well as aiding the pre-operative discussion amongst the medical team.

Adult↗

PubMed1990

Versatile digital data logger: storage of gastrointestinal motility data.

An inexpensive four-channel data logger for recording gastrointestinal potentials is described. A 512 K bytes memory and a sampling speed of 1.25 Hz per channel is adequate for these potentials and permits recordings for up to 27 hours. The small size and light weight allow the device to be carried in a pocket so that recordings can be made while the subject is freely ambulatory. A separate replay unit allows the data stored in the data logger to be presented to a chart recorder or to an interface card in a PC AT. This interface, a Microsoft C vers 5.0 program and the computer display the data as single frames or scrolled, expanded or condensed on either the time or amplitude axis. From the computer the data can be written to a printer and displayed as a chart or to an ASCII format file which can be used for analysis with statistical packages. Examples of recordings from both man and dog are illustrated and the analogue recorded data are compared with data digitally recorded. It is suggested that the data logger has many applications where long-term slow potential changes must be recorded under specially difficult conditions.

Action Potentials↗

PubMed1987

[Computerized data storage of antibiograms obtained by various methods (automatic reading by 2 different systems or manual processing by the disk method) and retrieval of antibiograms and cytobacteriological data using microcomputers].

This software is composed of different programmes. It works on Apple IIe computers. It enables to capture all the data information concerning bacteriological tests to store them and to edit either personnel reports or global lists made out according to different criteria and to study them under both the statistical or the epidemiological aspects. The results of the antibiotic sensitivity test are notified either by an automatic reader (ABAC or API system) when carried out in a liquid environment or by an original computerized device (compass or enlarger) when manually carried out by the disc method. The informations are directly transmitted to the computer. It's possible to make up a common data file that can be exploited as a whole.

Bacteriological Techniques↗

PubMed1991

Implantable cardioverter defibrillator: data storage and retrieval with Patientlog.

A pacemaker management system (Patientlog), implemented on a IBM personal computer (AT), was adapted for the control and the administrative management of patients with an implantable cardioverter defibrillator (ICD). Several parameters used for pacemakers were also suitable for ICDs, while some fields were defined within the available frame of the database, to cope with the specific technical information of ICDs. "Intervention-cards" display diagnostic (threshold) as well as complex surgical information (approach, lead systems, etc.). "Follow-up-cards" present charge time and the number of shocks in such a way that decision making is very easy. Fourteen patients were followed with a total of 21 interventions, six different types of devices, and more than 150 follow-ups. A correct control of ICD functions is easy. The system is adapted for programmable ICDs. Updated reports containing necessary information are generated immediately after each procedure or follow-up.

Database Management Systems↗

PubMed1985

A high capacity data recording device based on a digital audio processor and a video cassette recorder.

A modified digital audio processor, a video cassette recorder, and some simple added circuitry are assembled into a recording device of high capacity. The unit converts two analog channels into digital form at 44-kHz sampling rate and stores the information in digital form in a common video cassette. Bandwidth of each channel is from direct current to approximately 20 kHz and the dynamic range is close to 90 dB. The total storage capacity in a 3-h video cassette is 2 Gbytes. The information can be retrieved in analog or digital form.

Computers↗

PubMed1986

A non-radioactive automated method for DNA sequence determination.

A method and instrument for automated DNA sequencing without radioactivity have been developed. In spite of the success with radioactive labels there are drawbacks attached to the technique, such as hazards in the handling, storage and disposal of radioactive materials, and the considerable cost of the radiolabelled nucleoside triphosphates. In addition, there is deterioration of sample quality with time. A sulphydryl containing M13 sequencing primer has been synthesised and subsequently conjugated with tetramethylrhodamine iodoacetamide. The fluorescent primer is used to generate a nested set of fluorescent DNA fragments. The fluorescent bands are excited by a laser and detected in the gel (detection limit about 0.1 fmol per band) during electrophoresis, and sequence data from the four tracks are transferred directly into a computer. Standard gels, 200 mm wide with 20 sample slots have also been used. The device contains no moving parts. At present 250-300 bases can be read in 6 h. The system is capable of single base resolution at a fragment length of at least 400 bases.

Autoanalysis↗

PubMed1977

[Image processing in pathology. III. Structure and use of an automatic morphometry system for recording morphometric features of nuclei (author's transl)].

UNLABELLED: An image processing system for morphological investigation of liver cell nuclei in biopsy specimens is demonstrated. The present study deals with the age dependence of normal hepatic nuclear areas. The results were compared with those of conventional methods. MATERIAL AND METHODS: The image processing system consists of a microscope, an image dissector and a computer (central processing unit, display, teletype, magnetic tape devices and line printer). 74 liver biopsies were investigated. They sshowed no signs of acute or chronic diseases. Paraffin sections of 4 micron in thickness were prepared and stained by Feulgen method. 8-10 biopsies were available for each decade from 1-8. 18,000 liver cell nuclei from all specimens were isolated and measured automatically. Using the image processing system and adequate computer programs 20 parameters of all isolated nuclei were gained (parameters of shape, size and structure of the nuclei). For sampling and processing of the information the following programs are developed: PROBE Program for investigation of optimal parameters of scanning and processing. SAMPL Program for scanning, object isolation, feature extraction and storage of data records. KORRL Program for investigation of correlations between the features of objects. LISTE Program for listing of data records. ULTRA Program for search of objects with extremal features. CODER Program for correction od data records. ADAPT Program for training of classificators. SCHAU Program for demonstration and checking of the classificator. MORPH Program for output of feature distributions and statistical parameters. Following object features were calculated and investigated: features of size: KOFL area within the object contour; KKFL minimal covex area of the object; ZKFL object area without holes; KONL length of the object contour.

Adolescent↗

PubMed1990

Enhancement and compression of digital chest radiographs.

The application of digital technologies to chest radiography holds the promise of routine application of image processing techniques to effect image enhancement. Because of their inherent spatial resolution, however, digital chest images impose severe constraints on data storage devices. Compression of these images will relax such constraints and facilitate image transmission on a digital network. We evaluated an algorithm for enhancing digital chest images that has allowed significant data compression while improving the diagnostic quality of the image. This algorithm is based on the photographic technique of unsharp masking. Image quality was measured with respect to the task of tumor detection and compression ratios as high as 2:1 were achieved. This compression can be supplemented by irreversible methods.

Algorithms↗

PubMed1985

[Automated and semiautomated perimetry. Comparative trial of 3 devices (Baylor programmer, Friedmann Mark II campimeter, Octopus 2000 R.)].

Modern perimetry involves automated or semi-automated procedures, this computer assisted perimetry (CAP) providing results independent of the examiner, and with marked discrimination of light sensibility through quantification of points tested. A wide variety of CAP devices are available, and a comparative study was conducted in 50 patients using 3 perimetric apparatuses with similar supraliminal static techniques but with variable automated potentials: The Goldman perimeter modified by "Baylor visual fields programmer": static technique for the middle area and kinetic for the peripheral area. The Friedmann Mark II Visual Fields Analyser with a multiple stimulus static technique for the middle area. The Fankhauser Octopus 2000 R perimeter with a precise static technique for middle and peripheral areas. This perimeter, highly automated, also allows statistical evaluation of defects changes, owing to storage of results on magnetic discs. Patients studied had either: glaucoma (25 cases) or neuro-ophthalmologic and retinal disorders (24 cases). Conclusions drawn from the experience acquired by the authors during more than one year of use of the 3 devices were: Rate of detection of defects is excellent with the Octopus and quite good with the Friedmann MKII, but limited in the middle area. The Baylor program does not allow quantification of defects. The image is clear with the Octopus as far as the gray scale is concerned, and more exact as far as the comparative tables are concerned; is not clear with the Friedmann MKII; is typical and clear with the Baylor. The length of examination (which varies with the programs used as far as the Octopus is concerned, and with the patient's reaction time) is usually long with the Octopus and the Friedmann, but short with the Baylor. Time and energy can be gained by the use of the Octopus, since it supplies data obtained from use of the Baylor program associated with that of the Friedmann MKII. The authors prefer to follow up campimetric evolution of glaucomatous patients with the Octopus because it offers more sensibility and precision in quantifying losses. The application of the statistical evaluation delta program on the 2000 R device, which will soon be tested in the Ophthalmological Department, could in an objective way indicate whether there is stabilization or a real progression of glaucomatous defects.

Adenoma↗

PubMed1991

A distributed approach to integrated inquiry and display for radiology.

Picture archive and communications (PACS) systems should be flexible and modular in design so that new advances in storage, computation, and display technology can be introduced into the system without a significant redesign of existing software. The acquisition, storage, and management of radiologic images must be carefully integrated with a radiology information system. Our architecture is based on a four-level data model: (1) patient information, (2) examination information and reports, (3) image information, and (4) instances of images. The PACS being developed at the Mallinckrodt Institute of Radiology within the Electronic Radiology Laboratory consists of three primary components: application clients, database servers and image servers. One type of application client is an image-capable workstation that supports a radiology image viewing application. The application client queries the database server for information regarding patient and examination data in response to user-level requests. The database server responds to the request by retrieving the appropriate patient demographics and examination information, along with a pointer to the image/instance data from a central database. The client then uses the image data pointer to query the image server for the actual pixel data. The image server responds by transmitting the pixel data to the requesting application client or a designated auxiliary display device. Other clients act as image data acquisition nodes. Queries to the database servers are made via a library of callable subroutines. Software integrity is maintained throughout the system by dynamically loading software from a code-control database. Inquiry and display transactions, supported on a local-area network (Ethernet), have been measured and analyzed. Results and observations are presented.

Computer Communication Networks↗

PubMed1990

Medical expert systems: design and applications in pulmonary medicine.

Expert systems are computer applications with a built-in knowledge of a special field to solve problems like a human expert on this subject. An expert system consists of an inference component for problem specification and solving, a knowledge base for storage of data, facts, rules and heuristics, an interface for knowledge acquisition, another for the interaction with the user, and a component for reasoning. Pulmonary expert systems are used for automatic interpretations of lung function data which are measured on-line and directly computed. There are also some expert systems for consultation in difficult pulmonary cases and for protection against overlooking rare diseases. Perhaps the most successful applications of pulmonary expert systems are for educational purposes and a large variety of teachware is available. Pulmonary expert systems are presently limited to small applications; often it is necessary to type in large amounts of data and to follow a deeply structured cumbersome dialog. Also, the problem of responsibility for computer decisions has to be mentioned. But pulmonary expert systems as integrated supplements of normal pulmonary measuring devices, as decision support, and as parts of pulmonary teachware will be helpful tools for the pneumological physician.

Artificial Intelligence↗

PubMed1989

[Technical and methodologic aspects of ambulatory long-term blood pressure monitoring systems].

The development of noninvasive, portable blood pressure measuring units began in 1962 with semi-automatic devices and cassette recorders, followed by the first automatic unit in 1968 and the introduction of digital storage system in 1978. Systems in common use today consist of a portable, battery-driven blood pressure monitor and a print-out unit. In the following, the System 5200 from SpaceLabs, which has been in use for three years in our clinic, will be described. TECHNICAL ASPECTS: In a monitor unit, amplication and filtering of analogue data measured and differentiation between signal and noise is carried out. An A/D converter digitalizes the analogue data. An integrated microprocessor analyses measured data, regulates inflation and deflation of the cuff pressure, out-put of measured and calculated values on an LCD display and storage of data. Data from 200 measurements is stored in a 2K byte RAM CMOS system. A personal computer serves for programming the monitor and evaluation of the stored data. Blood pressure measurement is carried out auscultatory with a microphone or oscillometrically if Korotkoff sounds are not detected. If the signal is disturbed, measurement is repeated within two minutes. Blood pressure measurements are performed at freely-programmable intervals from six to 60 minutes; varying time intervals can also be chosen. AUSCULTATORY BLOOD PRESSURE MEASUREMENT: A miniature pump integrated in the monitor inflates the cuff within a few seconds to a pressure of 160 mmHg or, on subsequent measurements, to 25 mmHg above the last recorded systolic value. On registration of Korotkoff sounds, the cuff pressure is increased in steps of 25 mmHg until the sounds disappear and then deflated in steps of 3 to 5 mmHg. On detection of the first Korotkoff sound, the instantaneous cuff pressure (which is converted to an electric signal by a transducer) is stored as the systolic value. Further deflation then occurs rapidly to 90 mmHg or 10 mmHg above the last measured diastolic value. With higher diastolic values, again, there is an increase in cuff pressure in steps of 25 mmHg until the onset of Korotkoff sounds and then renewed deflation in steps of 3 to 5 mmHg. On disappearance of the Korotkoff sounds, the prevailing cuff pressure is recorded and stored as the diastolic value (Figure 1). To register the Korotkoff sounds optimally, the microphone is positioned above the brachial artery.(ABSTRACT TRUNCATED AT 400 WORDS)

Ambulatory Care↗

PubMedDate not supplied

Automated system for measurement of mechanics of breathing.

We describe a complete automated system for measurement of total respiratory resistance and compliance, and of pulmonary resistance and compliance in humans and anesthetized animals. The device for testing the chest-lung system consists of a sinusoidal pump with a stroke adjustable from 20 ml to 600 ml over a cycling frequency of 0.3 to 30 Hz. Pressure and flow or volume are inputted into an analog network for wave shaping, then to an arithmetic unit composed of sample-and-hold amplifiers, peak, minimum and zero detecting circuits, an analog division circuit, and a digital logic processor. The computer takes the peak-to-peak amplitude of one of two sinusoidal inputs at 0.3 to 10 Hz and the corresponding amplitude of the other input in the presence of a.c. noise and d.c. shifts, divides one into the other, and displays an answer on a digital voltmeter. In addition, the analog output is displayed on the cathode-ray tube of a storage oscilloscope. Plots of total resistance and pulmonary resistance are recorded as a function of lung volume in both humans inspiring voluntarily as well as anesthetized dogs inflated by positive pressure from the test apparatus. Total and pulmonary dynamic compliance, as a function of breathing frequency, can only be measured by the computer if a symmetrical waveform is presented to it. This cannot be achieved in spontaneously breathing subjects but is accomplished in apneic animals by producing sinusoidal oscillations from the test apparatus. Our on-line method for measurement of total respiratory resistance is now used in the Clinical Pulmonary Laboratory for experimental work, and we are in the process of obtaining values in normal subjects.

Adult↗