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At least 1,279 records · Page 71Linked to original sources
PubMed1993

An automatic monitoring system for epithelial cell height.

This paper describes an automatic method to measure cell height (h) of epithelia grown as monolayers on transparent filter supports. Tissues are mounted in an Ussing-type chamber enabling solution exchange on both sides. The apical and basal side of the epithelial cells are marked with fluorescent beads. The image of the fluospheres is captured with a video camera and processed by a computer-based video imaging system. One basal reference bead in a gelatin layer on the filter support and up to three beads attached at the apical surface are used to monitor changes in cell height of three cells simultaneously. The focusing of the microbeads is done automatically by moving the objective with a piezoelectric device mounted on the nosepiece of the microscope. The algorithm for locating the bead is based on the changes in fluorescent light intensity emitted by the fluospheres. The method has an accuracy higher than 0.1 micron and a time resolution as low as 6 s if measurements are restricted to one bead at the apical side. The method was tested on artificial model systems and used to measure volume changes in renal cultured epithelia (A6) after exposing the serosal surface to hypotonic solutions and replacing cell-impermeable sucrose by an organic compound (glycerol) with a smaller reflection coefficient. Serosal hypotonicity elicited a rapid volume increase followed by regulatory volume decrease, whereas the organic compound replacement caused a steady increase in cell volume.

Autoanalysis↗
PubMed1988

Human automatic postural responses: responses to horizontal perturbations of stance in multiple directions.

The effect of the direction of unexpected horizontal perturbations of stance on the organization of automatic postural responses was studied in human subjects. We recorded EMG activity from eight proximal and distal muscles acting on joints of the legs and hip known to be involved in postural corrections, while subjects stood on an hydraulic platform. Postural responses to horizontal motion of the platform in 16 different directions were recorded. The amplitude of the EMG responses of each muscle studied varied continuously as perturbation direction was changed. The directions for which an individual muscle showed measurable EMG activity were termed the muscle's "angular range of activation". There were several differences in the response characteristics of the proximo-axial muscles as opposed to the distal ones. Angular ranges of activity of the distal muscles were unipolar and encompassed a range of less than 180 degrees. These muscles responded with relatively constant onset latencies when they were active. Proximo-axial muscles, acting on the upper leg and hip showed larger angular ranges of activation with bimodal amplitude distributions and/or onset latency shifts as perturbation direction changed. While there were indications of constant temporal relationships between muscles involved in responses to perturbations around the sagittal plane, the onset latency relationships for other directions and the response amplitude relationships for all directions varied continuously as perturbation direction was changed. Responses were discrete in that for any particular perturbation direction there appeared to be a single unique response. Thus, while the present results do not refute the hypothesis that automatic postural responses may be composed of mixtures of a few elemental synergies, they suggest that composition of postural responses is a complex process that includes perturbation direction as a continuous variable.

Adult↗
PubMed1992

Automatic antifungal activity analyzing system on the basis of dynamic growth process of a single hypha.

A system for the evaluation of antifungal activity of volatile compounds has been developed that is based on dynamic growth of a single hypha. The newly developed system is composed of a reaction vessel under a microscope, automatic stage, charge coupled device (CCD) camera, TV monitor, video tape recorder (VTR), and a microcomputer. A fungus was inoculated in the reaction vessel containing agar medium and then was treated with an antifungal reagent in the gas phase either in batch or flow reaction manner. The apex of a growing hypha displayed on a TV monitor was followed automatically. From the ratio of the growth rate under exposure of a reagent (UEXPO) to the growth rate before the exposure (UPRE), the antifungal activity was expressed quantitatively.

Antifungal Agents↗
PubMed1976

Automatic recording and evaluation of neuronography.

The introduction in the 60' s of the Nerve Excitability Test (NET) by Laumans and Jongkees for the diagnosis of Bell's palsy stimulated an interest of quantitative testing of the facial nerve. In 1970 Yanagihara reported the Evoced Myography (EMG; i.e. NET is combined with EMG). Starting with electrophysiological basis of the impulse spread of peripheral nerves May, in 1971, extended this concept by including supraliminal stimuli, i.e. Maximal Stimulation Test (MST), for diagnostic purposes. This method eventually developed into what is known as neuronography (Esslen, Huffmann, Ehrenberger, Satoh). It is undoubtedly a refinement in the question of prognosis of Bell's palsy. Continuing the original concept of May we have developed an electronic device with which to carry out automatically the neuronography that demonstrates an evaluation on a numeric display. We use the conventional bipolar negative square wave for a 1 ms stimulation. We stimulate the angle of the mandible, where the ramus marginalis can be readily found in all patients. Neuronography and Evoked Myography provide earlier a more precise prognosis of facial palsy than Nerve Excitability Test (NET). We developed an electronic device for the Maximal Stimulation Test (MST) of May, M., that is automatic. The device counts the spikes of the evoked myogram. A time window is related to the stimulus to exclude stimulus noise and background muscle noise from the counter. Only spikes seen in this window are processed. The number of spikes generated per stimulus is the measurement of the live axons in a stimulated nerve.

Electronic Data Processing↗
PubMed1985

Automatic determination of labeling density in protein A-gold immunocytochemical preparations using an image analyzer. Application to peroxisomal enzymes.

The application of an automatic image analyzer (TAS, Leitz, Wetzlar) for determination of labeling density in protein A-gold labeled sections is described. Electron micrographs of rat liver labeled with 12 nm gold particles for peroxisomal enzymes are placed on the macrounit of TAS and the images of peroxisomes on TAS-monitor are contoured with a light pen. The instrument measures the surface of the contoured areas. Based on their gray level, the gold particles over the peroxisome are detected automatically and counted and the labeling density for each peroxisome is calculated.

Acetyl-CoA C-Acyltransferase↗
PubMed1975

An automatic perimeter for glaucoma visual field screening and control. Construction and clinical cases.

An apparatus for static perimetry of the central visual field at 64 points is described. The testing is fully automatic: the test logic is programmed into a mini-computer and the results are plotted as a diagram in polar coordinates. A few cases with small or medium sized visual field defects have been analyzed by conventional methods and by the automatic instrument with satisfying results.

Adult↗
PubMed1978

Effects of calcium-antagonistic coronary vasodilators, nifedipine and verapamil, on ventricular automaticity of the dog.

In isolated, blood-perfused canine papillary muscles intra-arterial injection of calcium-antagonistic coronary vasodilators, nifedipine and verapamil, produced a dose-related decrease in force of contraction. The ventricular rate of about 40 beats/min was not significantly changed by nifedipine even in doses which profoundly decreased the force of contraction. Verapamil changed the ventricular rate in a biphasic manner, but the changes remained as small as about 10% of the basal rate in doses which markedly suppressed the force of contraction. Calcium chloride elicited an increase in force of contraction but depressed automaticity. The present results show that in response to nifedipine, verapamil and calcium ions, ventricular automaticity has characteristics different from those of the sinus node.

Animals↗
PubMed1994

Measurement of CO2 response with the breath-by-breath automatic acquisition of the breathing pattern and occlusion pressure.

OBJECTIVE: Our objective is to present a methodology for the automated acquisition and storage of BP and P0.1 during a CO2 rebreathing test. METHODS: The system consists of a microcomputer with additional circuits and an automatic electronically controlled valve to occlude the inspiratory airway. Data collection and data processing are separate programs. Airway pressure and flow are digitized at a 100-Hz rate, while PETCO2 is determined and P0.1 is measured on a breath-by-breath basis. Off-line processing calculates the BP variables, generates a correlation matrix (VE/PETCO2, TTOT/PETCO2, TI/PETCO2, TE/PETCO2, [VT/TI]/PETCO2, [TI/TTOT]/PETCO2, P0.1/PETCO2), and edits graphic data. The accuracy of the volume and pressure measurements was tested by comparing known volumes provided by a syringe (n = 100) and a series of pressures controlled by a water manometer (n = 41) on the one hand, with volumes and pressures measured by the device. The accuracy of the time intervals and P0.1 was assessed by comparing in 10 healthy subjects the values measured manually on a graphic recording with those provided by the device (n = 170). RESULTS: Volumes:Vmeasured = 0.99 x Vcontrolled, r = 0.99, p < 0.001. Pressures:Pmeasured = 0.97 x Pcontrolled + 0.09, r = 0.98, p < 0.001. Inspiratory time:TIautomatic = 0.91 x TIgraphic + 0.22, r = 0.93, p < 0.001. Expiratory time:TEautomatic = 0.93 x TEgraphic + 0.34, r = 0.95, p < 0.001. Occlusion pressure:P0.1automatic = 0.95 x P0.1graphic + 0.62, r = 0.94, p < 0.001. Reproducibility was assumed to be represented by the intraindividual coefficient of variation of the CO2 response. The comparison of an automatic breath-to-breath method with a graphic manual recording revealed significantly less variability with the former (VE/PETCO2: 15.2 +/- 4.5% vs 22.5 +/- 6.3%, p < 0.01; P0.1/PETCO2:8.3 +/- 4.3% vs 19.7 +/- 7.2%, p < 0.001; [VT/TI]/PETCO2:9.1 +/- 3.5% vs 14.5 +/- 5.3%, p < 0.05). CONCLUSION: Our automated acquisition and storage of waveforms and breath-by-breath determination of BP and P0.1 provide an easy and thorough analysis of the respiratory response to CO2 and decrease the variability of the results.

Anesthesia, Closed-Circuit↗
PubMed1996

The role of Ca2+ release from sarcoplasmic reticulum in the regulation of sinoatrial node automaticity.

The role of Ca2+ release channels in the sarcoplasmic reticulum in modulating physiological automaticity of the sinoatrial (SA) node was studied by recording transmembrane action potentials and membrane ionic currents in small preparations of the rabbit SA node. Ryanodine, which modifies the conductance and gating behavior of the Ca2+ release channels, was used to block Ca2+ release from the sarcoplasmic reticulum. Superfusion of 1-mM ryanodine decreased the spontaneous firing frequency as well as the maximal rate of depolarization of the SA, and these reductions reached a steady state within approximately 5 min. The action potential recordings revealed that the latter part of diastolic depolarization was depressed and that the take-off potential became less negative. This suggested that the negative chronotropic effect of ryanodine resulted from the blockade of physiological Ca2+ release from the sarcoplasmic reticulum. In voltage clamp experiments, using double-microelectrode techniques, ryanodine did not markedly reduce the Ca2+ current (ICa) but decreased the delayed rectifying K+ current (IK), the steady-state inward current (Iss), and the hyperpolarization-activated inward current (Ih). These observations suggest that, even when the function of C2+ channels in the cell membrane is normally maintained, depression of Ca2+ release channels in the sarcoplasmic reticulum would prevent sufficient elevation of the Ca2+ concentration in SA node cells for the activation of various ionic currents, and, thus adversely affect the physiological automaticity of this primary cardiac pacemaker.

Action Potentials↗
PubMed1995

Echocardiographic assessment of systolic and diastolic left ventricular function using an automatic boundary detection system. Correlation with established invasive and non invasive parameters.

Systolic and diastolic left ventricular function was assessed using an echocardiographic automatic boundary detection system (ABD) in 50 unselected patients undergoing left cardiac catheterisation. Automatic boundary detection system derived parameters (fractional area change [FAC], peak positive rate of area change [+dA/dt] and peak negative rate of area change [-dA/dt]) were compared with invasively (left ventricular angiography and pressures) and non invasively (Doppler mitral filling velocities and isovolumic relaxation time) acquired conventional indices of ventricular function. Adequate detection of endocardial boundaries and subsequent measurements using the ABD system were achieved in 40/50 (80%) patients in the short axis parasternal view, in 41/50 (82%) in the apical four chamber view and in 34/50 (68%) in both views. For the whole group of patients the FAC (maximal left ventricular diastolic area--minimal left ventricular systolic area/maximal left ventricular diastolic area) estimated in the short axis view correlated with the angiographic ejection fraction (EF) measured in the right oblique projection (r = 0.51, p < 0.001). There was only a weak correlation of the FAC estimated in the apical four chamber view with the EF (r = 0.36, p < 0.01). The mean FAC (mean value of the FAC in the short axis and apical four chamber views) correlated reasonably with the EF (r = 0.62, p < 0.0001). There was no correlation between ABD derived parameters and left ventricular end diastolic pressure (LVEDP) in these patients. In a subgroup of patients with normal coronary arteries and left ventricular function (n = 17), although there was no correlation between EF and FAC, there was a strong positive correlation between FAC (apical four chamber and mean) and LVEDP (r = 0.77, p < 0.01 and r = 0.87, p < 0.01 respectively). No correlation was found in these patients between EF and LVEDP. In a further subgroup of patients with angiographically abnormal left ventricular function (EF < 45%), there was a positive correlation between FAC (short axis, apical four chamber and mean) and EF (r = 0.52, p < 0.05, r = 0.83, p < 0.0001 and r = 0.80, p < 0.001 respectively) and a negative correlation between FAC (short axis and mean) and LVEDP (r = -0.52, p < 0.05 and r = -0.60, p < 0.01 respectively). There was also a negative correlation between LVEDP and EF in the same subgroup of patients (r = -0.65, p < 0.01).(ABSTRACT TRUNCATED AT 400 WORDS)

Adult↗
PubMed2002

Automatic algorithm for filtering kinematic signals with impacts in the Wigner representation.

An automatic filtering algorithm is proposed for the accurate estimation of the second derivatives of kinematic signals with impacts. The impacts considered here occur when a moving object hits a rigid surface. The algorithm performs time-frequency filtering in the Wigner representation, to deal efficiently with the non-stationarities caused by such impacts, and adjusts the parameters of its time-frequency filtering function so that the filtering process adapts to the individual characteristics of the signal in hand. Performance analysis and comparative evaluation with experimentally acquired kinematic impact signals demonstrated a higher accuracy, with performance advantages over two widely used conventional automatic methods: linear phase autoregressive model-based derivative assessment (LAMBDA) and generalised cross-validation using quintic splines (GCVQS). For high impacts, the average absolute relative error in estimating the peak acceleration was 5.7% with the proposed method, 17.2% with a Butterworth low-pass filter optimised to yield minimum overall acceleration RMS error (best-case result), 18.3% with the LAMBDA method, and 37.2% with the GCVQS method. For signals with low impacts, the average absolute relative error was 19.4%, 6.9%, 8.3% and 19.1%, respectively, in each case, which indicates that, for signals with a low-frequency content, there is no need for such time-frequency filtering.

Algorithms↗
PubMed2005

Automatic stimulus breaker for electric dental pulp tester using pain response.

The pulp test provides a means of examining the vitality of dental pulp using physical or chemical stimulation. During electrical pulp testing, an electrical current stimulates the intradental nerve, which may be painful and stressful to patients. The study involved measurement of the electromyogram (EMG) from the anterior belly of the digastric muscle, finger movement and voice response during electrical pulp testing. The excessive stimulus time from the onset time of response (EMG, voice and finger movement) to the end of the stimulation was obtained. The results indicated that the responses occurred in the order: EMG, finger and voice. Based on these results, an automatic stimulus shut-off circuit was developed using the above-mentioned responses to stimulus during electric pulp testing. Excessive stimulus time was reduced by prompt switching-off of the pulp tester output, 64 ms on average after the first detected response (EMG). Consequently, excessive stimulus times were reduced by 284 and 152 ms on average for the subject and examiner disconnection, respectively, using the developed automatic shut-off circuit. Therefore it was possible to minimise pain and stress by reducing excessive pulp stimulation.

Adult↗
PubMed2005

Automatic optimum order selection of parametric modelling for the evaluation of abnormal intra-QRS signals in signal-averaged electrocardiograms.

Abnormal intra-QRS potentials (AIOPs) in signal-averaged electrocardiograms have been proposed as a risk evaluation index for ventricular arrhythmias. The purpose of the paper was to develop an automatic algorithm for selecting the optimum parametric model order in the analysis of AIOPs to make the modelling approach clinically more feasible. A total of 130 normal Taiwanese subjects and 87 patients with ventricular premature contractions and 23 with sustained ventricular tachycardia were recruited. The unpredictable AIQP signal was estimated from the modelling residual. The cross-correlation coefficient between the original signal and the ORS estimate was employed to evaluate the accuracy of the estimate. A pre-selected threshold cross-correlation coefficient of 0.9999 was used to determine the optimum order. The mean AIQP in lead Y for ventricular tachycardia patients was 3.9 microV, which was significantly smaller than 4.9 microV for ventricular premature contraction patients (p < 0.01) and 6.3 microV for normal subjects (p < 0.001). The linear combination of AIQP in lead Y and the time-domain parameter RMS40 provided the best global performance (the area under the receiver operating characteristic curve was 89.1%). A higher risk of ventricular arrhythmias was associated with lower AIQP in lead Y, and the automatic modelling algorithm improved the clinical feasibility of AIQP analysis.

Aged↗
PubMed2004

Automatic estimation of endothelium cell density in donor corneas by means of fourier analysis.

One of the main clinical parameters expressing the health of a cornea is the cell density of its endothelium. This information is particularly important in an eye bank environment, where donor corneas are screened to assess their suitability as a human graft. Endothelium cell density is conventionally estimated by a long, tedious and error-prone manual counting procedure, performed by cornea experts on specimen images observed through an optical microscope. An alternative solution is proposed: a computer program that provides automatic estimation of cell density in donor corneas by analysing the spatial frequencies contained in the image. A circular band in the 2D discrete Fourier transform of the image is shown to contain the relevant information about the cell density. A system for extracting from this spatial frequency information an estimate of the cell density has been developed. A clinical evaluation of the proposed technique was performed on 18 corneas, where the densities provided by the proposed technique were compared with those manually obtained by two experts. The results showed an average percentage difference of 3% (maximum 19%), a value well within the measured inter-expert range of variability. The proposed automatic procedure confirmed its ability to estimate correctly corneal endothelium cell density.

Algorithms↗
PubMed2003

Automatic analysis of electro-encephalogram sleep spindle frequency throughout the night.

A fully automatic method to analyse electro-encephalogram (EEG) sleep spindle frequency evolution during the night was developed and tested. Twenty all-night recordings were studied from ten healthy control subjects and ten sleep apnoea patients. A total of 22,868 spindles were detected. The overall mean spindle frequency was significantly higher in the control subjects than in the apnoea patients (12.5 Hz against 11.7 Hz, respectively; p<0.004). The proposed method further identified the sleep depth cycles, and the mean spindle frequency was automatically determined inside each sleep depth cycle. In control subjects, the mean spindle frequency increased from 12.0 Hz in the first sleep depth cycle to 12.6 Hz in the fifth cycle. No such increase was observed in the sleep apnoea patients. This difference in the spindle frequency evolution was statistically significant (p<0.004). The advantage of the method is that no EEG amplitude thresholds are needed.

Adult↗
PubMed1989

Algorithm for data reduction and automatic analysis of intestinal motility tracings and other smooth biological signals.

An algorithm is presented for the processing of smooth biological signals with an important implicit data reduction. It is a solid basis for an automatic analysis of these signals. The algorithm is based on the approximation of the signals with a linear combination of cubic B-splines. Depending on the parameters, a data reduction of between 8:1 and 12:1 can be achieved. The most important differences from conventional biological signal processing methods are the representation of the signal by the coefficients of the linear combination instead of a series of samples and the analysis by calculations of the time of the appearance of patterns instead of iterative searching. The approximation and analysis of long-lasting multichannel signals can be performed online with a modern microprocessor. Approximating the signal with a linear combination of cubic B-splines with equally spaced knots, according to the linear least-squares criterion gives the desired data reduction and an elegant way to perform an automatic analysis. A window calculation scheme makes it possible to handle very long signals online.

Algorithms↗
PubMed1999

Feasibility of using the automatic generating system for quartz watches as a leadless pacemaker power source.

An automatic power-generating system (AGS) which converts kinetic energy into electric energy for quartz watches was tested as a power source for implantable cardiac pacemakers. An automatic power-generating mechanism and a capacitor (0.33 F) were removed from a quartz watch (SEIKO) and encapsulated in a polyvinyl case. Characteristics of the AGS were investigated by acceleration equipment. The capacitor in the AGS was charged to 2.0 V (0.66 J) by placing it on the equipment for about 30 minutes. The equipment has a 2 Hz cycle and generates +/- 1.7 G at the end of each half cycle. The AGS (fully charged to 2.0 V) was used as the power source for a pulse generator circuit built using commercially available CMOS IC. The circuit generated pulses of 0.5 ms width at 1 Hz (60 pulses min-1). The voltage of the AGS was maintained at 1.6 V while it was being charged by the accelerations. The generator supplied pulses of 0.75 V, 1.47 mA through a 510 omega load. With fully charged AGS, the generator was also used to pace a mongrel dog's heart at 140 beats min-1 for 60 minutes. During pacing, the AGS supplied 420 mJ to the circuit and the cardiac muscle. The AGS was placed on the right ventricular wall of the mongrel dog under anaesthesia. Energy of 80 mJ is stored in a capacitor by the heart beating at about 200 beats/min for 30 minutes. Thus the AGS generated 13 microJ per heart beat. This result suggests that the AGS may supply enough energy for use in a cardiac pacemaker.

Electric Power Supplies↗
PubMed1976

Automatic gas tank switching system for CO2 incubators.

The use and construction of an automatic gas tank switching system are described. This device monitors the gas pressure in a CO2 incubator gas system and automatically switches to a reserve tank when the main supply tank is depleted. The unit contains an alarm system that signals either loss of power or gas pressure in the supply system.

Carbon Dioxide↗