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PubMedDate not supplied

Event-related potential evidence of dysfunction in automatic processing in abstinent alcoholics.

The preattentive automatic processing of 63 alcoholics and 27 controls was evaluated with an auditory inattentive event-related oddball paradigm. We examined the mismatch negativity and the N2-P3 complex. Results showed significantly greater amplitude for N2, P3 and the N2-P3 complex for controls but no individual lead (Fz, Cz, Pz) differences by group. A group-by-lead interaction was found for N2 and for the N2-P3 complex. There were no significant latency differences between groups; however, a significant age-by-group interaction effect on latency was greatest at the Cz electrode. Results reflect a possible aberration of automatic processing in alcoholics because of a defect in the mnemonic template necessary to match with an infrequent deviant stimuli. We also found suggestive evidence of a relative weakness of frontal cortical organization in alcoholics. Future studies are suggested that would help clarify these differences in alcoholics.

Acoustic Stimulation↗
PubMed1990

The use of automatic blood pressure monitors in the burned patient.

Oscillometric automatic blood pressure monitors are now commonly used in theatres and intensive care units. An experimental model has been used to assess the accuracy of these machines when measurements are made from a proximal limb cuff applied over bulky bandages, as is commonly found in burned patients. This study suggests that monitoring arterial blood pressure under these circumstances is sufficiently accurate to make automatic monitoring useful as an adjunct to burns management. This would allow blood pressure measurement where it would otherwise be impossible without invasive techniques.

Bandages↗
PubMed1975

An evaluation of the Gilford 3400 automatic enzyme analyser.

An assessment of the Gilford Automatic Enzyme Analyser was conducted over a period of one year. The optics of the instrument were satisfactory with regard to accuracy of wavelength selection and linearity of absorbance response. Excellent precision was obtained for both absorbance readings and operation of the dispenser pump. Carry-over within the microflow-cell was low. The method of operation recommended by the manufacturers for enzyme determinations failed to take account of endogenous blank reactions which could lead to significant error. When revised methods utilising a pre-incubation stage and initiation with a single substrate were employed, the results correlated well with those obtained with standard automatic (LKB 8600) and manual (Pye Unicam SP 800) kinetic systems for aspartate and alanine aminotransferase, creatine phosphokinase and alpha-hydroxybutyrate dehydrogenase, and the precision at all activity levels was satisfactory. Acceptable precision could not be obtained over the clinical range for enzyme assays requiring a blank determination on each sample (5'-nucleotidase and adenosine deaminase) and those with very low normal serum activities (isocitrate dehydrogenase and glutamate dehydrogenase). These limitations appeared to be due to relative insensitivity of the transducer response and liability to optical disturbance. This apart, the instrument has many advantages over alternative equipment.

Alanine Transaminase↗
PubMed1980

An automatic technique for the routine fractionation of the urinary hydroxyproline containing peptides.

A fully automatic method permits fractionation in a Biogel P2 column of the hydroxyproline-containing peptides into two fractions. The alkaline hydrolysis and the colorimetric evaluation of the liberated hydroxyproline are also completely automatic and allow calculation of the percentages of the two fractions. The first one, termed F1 fraction, contains the peptides of molecular weight larger than 1500, while the other, termed F2, contains the smaller peptides. The method was used for 223 assays. The F1 fraction is decreased in cases of Paget's bone disease. It is increased in cases of metastatic cancer of bone. Statistical analysis of the data demonstrates that this techique greatly improves the certainty of diagnosis when coupled to the assay of total hydroxyproline. When both total urinary hydroxyproline and the F1 fraction percentage are increased over threshold values of 485 mumol per 24 h and 28.4% respectively, the probability of the presence of a bone metastasis is 100%.

Adolescent↗
PubMed1993

Semi-automatic method for determination of different isoforms of carbohydrate-deficient transferrin.

Carbohydrate deficient transferrin (CDT) has been reported to be one of the best biochemical markers of alcohol abuse. However, a need still exists for a simple and practical method for widespread laboratory use. A semi-automatic (SA) isoelectric focusing (IEF) assay for CDT (SA-IEF-CDT) by a Phast System is introduced here. Different isoforms of transferrin were separated by IEF on polyacrylamide gels (pI 4.0-6.5) and located by immunofixation with an anti-transferrin serum. The precipitation bands were stained with Coomassie Brilliant Blue and quantitated densitometrically. The present method gave a picture of the relative amounts of 10 different transferrin isoforms. The percentage of CDT with pI > or = 5.7 (representing di-, mono- and asialotransferrin) was calculated. For comparisons transferrin bands with pI > or = 5.6 (tri-, di-, mono-, and asialotransferrin), pI > or = 5.8 (mono- and asialotransferrin) and pI > or = 5.9 (asialotransferrin) as well as GGT, ASAT and ALAT were calculated. The method showed good linearity and it identified different isoforms in concentrations of < 10 mg/l of transferrin. The correlation of the present method with a commercially available method employing anion exchange followed by double antibody RIA (AE-RIA-CDT) was good (n = 38, r = 0.924). In 19/20 (95%) of healthy controls, the CDT value was below 4.4% (mean + 2 S.D.) of total transferrin, while higher values were observed in all 20 (100%) alcoholics. In conclusion, the developed semi-automatic method is a practical and reliable alternative for determination of different transferrin isoforms.

Adult↗
PubMed1990

Automaticity: a new framework for dyslexia research?

The performance of a group of 23 13-year-old dyslexic children was compared with that of same-age controls on a battery of tests of motor balance. A dual-task paradigm was used--subjects performed each test twice, once as a single task, and once as a dual task concurrently with a secondary task. Two alternative secondary tasks were used, the classic counting-backwards task and an auditory choice reaction task. Both secondary tasks were calibrated for each subject to ensure that their performance on the secondary task alone fell between pre-specified performance criteria. In all single-task conditions there was no difference between the performance of the two groups. By contrast, in 19 out of the 20 tests performed under dual-task conditions, the dyslexic group were significantly impaired, whereas the controls showed no impairment, thus resulting in significantly better performance by the control group than the dyslexic group. The sole exception was that the dyslexic children were not impaired on the easiest balance condition with the choice reaction task. Under the dual-task conditions the dyslexic children also performed worse than the controls on the secondary task. It is very hard to accommodate the findings within the traditional framework of a deficit specific to lexical skills. One plausible explanation of the results is that, unlike the controls, the dyslexic children need to invest significant conscious resources for monitoring balance, and thus their performance is adversely affected by any secondary task which serves to distract attention from the primary task. This need for "conscious compensation" suggests that for dyslexic children the skill of motor balance is poorly automatized. It is possible, therefore, that many of the reading deficits of dyslexic children are merely symptoms of a more general learning deficit--the failure to fully automatize skills.

Adolescent↗
PubMed1976

Automatic treatment of assay data by competitive protein binding and radioimmunoassay.

A method is devised for the automatic computation of data obtained from a series of determinations by radioimmunoassay or by competitive protein binding. The input data is introduced by means of an automatic paper tape punch attached to the sample counter. A series of programs is set up for a Hewlett Packard computer, model 2116B with 16K, which calculates bound and free fractions with control processes for varying possible errors. From experimental data, by linear least squares regression, a standard curve of best fit is derived and is considered in three different ways. The curve of best fit is selected by comparing the correlation coefficients obtained and by calculating the unknown sample concentrations. The program presents the results graphically together with a list of results which is for use within the Radiochemistry laboratory. Individual reports are also prepared for sending to those departments that requested the test.

Binding, Competitive↗
PubMed1977

Automatic noctural sleep sampling: a useful method in clinical electroencephalography.

The clinical usefulness of obtaining a sleep record in epileptic patients is well established. However, in many clinical EEG laboratories, it is difficult to obtain records at night during the patient's natural sleep. Thus, most sleep EEGs are recorded in the EEG laboratory during daytime and are induced by drugs. A 16 channel cable-telemetry system is described which automatically samples throughout the night the EEG of patients while sleeping in their room or ward without the aid of any medication. The electrodes and the cable-telemetry unit are applied to the patient in the afternoon and the system is checked. The patient is then instructed to plug the system into a wall box upon retiring and to disconnect it when he wakes up in the morning. The EEG samples are automatically written out during the night on one of the EEG machines located in the EEG laboratory to which the system is connected via spectral intra-hospital wiring. The duration of the samples and of the intervals separating them can be varied according to the circumstances. We have found this method to be very helpful in the investigation of epileptic patients, especially those considered for surgical treatment.

Electroencephalography↗
PubMed1977

Automatic detection and localization of epileptic foci.

A new method of automatic EEG analysis (ASD or automatic non-stationarity detection) derived from a parametric EEG model (autoregressive filter model) and based on inverse filtering, has been applied to scalp and subdural EEGs of epileptic patients. By this method it was possible to detect the occurrence of transient non-stationarities such as paroxysmal patterns of activity (spikes, spike-and-waves) characteristic of inter-ictal EEGs. The ASD has been implemented in a general purpose digital computer. The method allows: (a) statistical evaluation of paroxysmal patterns; (b) multi-channel analysis, where the interrelationships of different derivations are quantified and displayed by means of a clinically useful spatial map. The application of the ASD method to scalp and subdural EEGs, simultaneously recorded, has revealed that a number of transient non-stationarities detected in the scalp by the program yet not by visual inspection, coincide with clear paroxysmal patterns in subdural derivations. In this way conventional definitions of characteristic paroxysmal patterns at the scalp are put in question. Identical conclusions regarding the localization of an epileptogenic zone in 4 patients were obtained either using the conventional methods of recording electro-clinical seizures in EEGs of long duration or applying the ASD method to short EEG epochs (100 sec long, at most).

Computers↗
PubMed1979

Automatic recognition of inter-ictal epileptic activity in prolonged EEG recordings.

A method of automatic recognition and quantification of inter-ictal epileptic activity in the human EEG had previously been developed and tested using short recordings from awake subjects. This paper describes the adaptation of the method for use during overnight recordings in free-moving unattended patients, in combination with the already existing seizure monitoring system. EEG s were recorded from scalp and sphenoidal electrodes, using cable telemetry and a PDP-12 computer. The spike and sharp wave recognition method allowed the on-line analysis of 16 channels. A section of the 16-channel EEG including 1 sec before and 1 sec after each detected spike was saved on digital magnetic tape. Upon completion of the monitoring session, the tape was played back on the EEG machine, giving a discontinuous tracing of spike sections; this constituted a highly concentrated view of the inter-ictal epileptic activity, in traditional paper form. The spike sections were further analyzed by computer to determine and display on the computer terminal the spatial and temporal distributions of the epileptic activity, providing a complete synopsis of the recording. Several examples of the type of information available from this anslysis are discussed in detail. False detection rates are given for 34 six hour recordings, indicating a high vari ability in the performance, mainly because of artefacts. It is concluded that the final computer displays could only be trusted after visual inspection of the EEG sections provided on paper. The variety of morphologies of artefacts appeared to preclude a total automatic elimination.

Electroencephalography↗
PubMed1980

Human and automatic validation of a phase-locked loop spindle detection system.

A further test of a phase-locked loop spindle detector is described. On the basis of comparison with both human visual scoring and with a second automatic system employing complex demodulation techniques, the detector's performance would appear to be adequate for most laboratories' needs. The errors in detection were largely shared by the two automatic systems.

Adult↗
PubMed1981

An automatic, optically isolated, biphasic constant current stimulator adapter for artefact suppression.

A stimulator adapter is described that automatically generates true biphasic constant current pulses from the single pulse output of a standard stimulator. Variations in the width or amplitude of the driving pulse are automatically duplicated in the biphasic pulses generated, permitting great ease of control of stimulating parameters. The device is simple, small in size and has a low current drain, permitting battery operation.

Electric Stimulation↗
PubMed1982

Application of digital filtering and automatic peak detection to brain stem auditory evoked potential.

A method to establish optimal parameters for automatic analysis of the BAEP was proposed. Spectral analysis of a set of BAEP trial averages yields criteria for the selection of the optimal bandwidth for digital filtering, establishes a lower limit for the number of averaged responses required for accurate determination of BAEP wave shape and permits accurate estimation of the amplitude and latency of BAEP peaks. Estimation of phase variance proved to be an effective procedure for selection of the optimal frequency band for automatic peak detection. Complete representation of the BAEP should include unfiltered and digitally filtered signals, an accuracy estimate of the filtered signal, and computer peak detection. High stability of detected peak latency values, as a result of using a digital filter with optimal parameters, will allow a reduction in the number of responses which must be averaged to obtain an accurate estimate of BAEP morphology. This should be of particular value where closely spaced serial observations are desirable, as in intra-operative monitoring. Procedures analogous to those described herein should permit reduction of the sample size required for accurate estimation of the morphology of far-field somatosensory evoked potentials, and for cortical potentials evoked by any stimulus modality. The consequent increase in the speed with which reliable measurements can be obtained can be expected to increase the practical application of all evoked potential techniques.

Brain Stem↗
PubMed1986

Automatic analysis overcomes limitations of sleep stage scoring.

A computer programme for the automatic analysis of the sleep EEG and EMG is presented. An EEG parameter is derived which is based on the joint frequency-amplitude distribution of the EEG activity. This newly developed parameter stresses the dynamic development of sleep, composed of alternating phases of EEG synchronization and desynchronization. While synchronization develops slowly, the opposite phase of EEG activity, desynchronization, is more rapid. A particular advantage of the EEG parameter is its continuous scale which results in high resolution. Thus, the parameter reflects gradual EEG changes which a visual analyser would have to classify into the same sleep stage. In addition to the EEG, the EMG is analysed and two parameters are extracted, representing the mean muscle tone and transient EMG activation, respectively. There is a close temporal relationship between the EEG and the EMG with a maximum of transient EMG activity during the phase of EEG desynchronization. The properties of the automatic analysis were compared to the visual analysis on a sample of 12 all-night sleep records. The results show that the EEG parameter also agrees sufficiently with the traditional sleep scoring method and therefore is a valid descriptor of the time course of sleep.

Electroencephalography↗
PubMed1995

Automatic auditory discrimination is impaired in Parkinson's disease.

Deviant tones embedded in a sequence of standard tones elicit an event-related potential (ERP) component called the mismatch negativity (MMN), which reflects automatic stimulus change detection in the human auditory system. To determine whether stimulus change detection is impaired in Parkinson's disease (PD), we recorded ERPs in 13 non-demented patients with PD and in 11 age-matched healthy control subjects both when tones were attended and when they were unattended. The difference area between deviant and standard ERPs was used to evaluate the MMN in the 'unattended' condition. The MMN was significantly smaller in patients with PD than in controls. In the attended condition, the amplitudes of both N1 and the N2 complex were smaller in the patient group than in controls. MMN attenuation suggests that PD patients have impaired automatic stimulus change detection compared with healthy controls. This might be caused by dopamine deficiency in PD.

Acoustic Stimulation↗
PubMed1988

Automatic sleep-wake scoring in the rat on microcomputer APPLE II.

An automatic scoring system in real time of sleep-wake behavior in the rat was elaborated on microcomputer APPLE II. Four electrophysiological recording channels were used to distinguish seven behavioral states. Because the rat shows behavioral stages which are short-lasting, the analysis is performed second by second. It is based on the detection of the signal energy in specific frequency bands. The percentage of time passed in each stage is computed every 15 min, 1 h, 6 h and 24 h, the analysis extending during several days without interruption. The data are also printed out in a listing in real time and histograms in batch mode. Because of the interindividual differences, a calibration is needed. It is performed with a program in batch mode which allows an adjustment of parameters of determination from given specific digitized sequence in each rat. The accuracy of the automatic method was tested by the C contingency test, the theoretical maximal level being at 0.93: the intra- and inter-researchers contingency was 0.89, that between researchers and the computer was 0.85.

Animals↗
PubMedDate not supplied

Automatic identification of significant graphoelements in multichannel EEG recordings by adaptive segmentation and fuzzy clustering.

A new approach to visual evaluation of long-term EEG recordings is proposed. The method is based on multichannel adaptive segmentation, subsequent feature extraction, automatic classification of the acquired segments by fuzzy cluster analysis (fuzzy c-means algorithm), and on the distinguishing of thus identified EEG segments by colour directly in the EEG record. The black and white variant of the described automatic system is presented. The method was evaluated by applying it to simulated artificial data and to real EEG recordings; some of the illustrative results are shown. In addition, the performance of this system is evaluated and the first experience with its application to routine EEG recordings is discussed.

Algorithms↗
PubMed1982

Automatic detection of fetal movement by Doppler ultrasound during non-stress testing.

A new external fetal monitor, using a defocused, wide-area ultrasound transducer has been devised in order to obtain a more accurate representation of fetal movement during antepartum non-stress testing. The fetal activity Doppler signal is easily distinguished from the fetal heart Doppler and provides an automatic record of fetal movement which is objective and reproducible. In several clinical tests, this new monitor was found to be more sensitive and reliable than either reports of fetal movement from the mother or from a physician palpating the abdomen. This method of automatic detection of fetal activity can improve the accuracy of the non-stress test by providing an additional objective criteria.

Fetal Heart↗