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PubMed1989

Abnormal optokinetic and perceptual span parameters in cerebellar-vestibular dysfunction and learning disabilities or dyslexia.

To measure the ocular fixation and sequential scanning dysfunction assumed responsible for the visual reading symptoms which characterize dyslexia or learning disabilities, an optokinetically based tracking method was devised. This method quantitatively demonstrated significantly reduced fixation, tracking, and perceptual or visual-span scores as well as "movement illusions" for 70 cerebellar-vestibular dysfunctioning persons with learning disabilities vs 70 controls. Such data tended to validate the hypothesis that cerebellar-vestibular-determined fixation and tracking mechanisms predispose dyslexic or learning disabled individuals to visual reading disorders. Moreover, a newly revised method is presented which may prove useful in rapidly screening and diagnosing cerebellar-vestibular-determined reading and learning disorders from those of other origins. Additional independent studies using significantly larger samples and asymptomatic or "normal" controls are required for further validation and development of the method.

Adolescent↗

PubMed1990

Automated tracking and computer reproduction of vessels in DSA images.

We are developing an automated vessel-tracking method based on the double-square-box region-of-search technique, for efficient tracking of the connected vascular tree in a digital subtraction angiography (DSA) image. Tracking points and branch vessels are located by searching of the perimeter of boxes, which are centered on previously determined tracking points. The most accurate results (90% true-positive rate with six false-positives per image) are obtained by tracking using the double-square-box method. In relatively straight regions of vessels, a large box is employed for efficient tracking; in curved regions of vessels, a small box is employed to ensure accurate tracking. When tracking is completed, accurate vessel information, ie, the vessel position, size, and contrast determined at each tracking point, is available for further quantitative analysis. Computer reproductions of tracked vessel trees appear to correspond well to those in DSA images.

Angiography, Digital Subtraction↗

PubMed1991

A syntactic analysis method for sinusoidal tracking eye movements.

A syntactic method for the recognition of sinusoidal eye movements is presented. The method is based on a piecewise transformation of an eye movement signal to strings of a formal language and use of a formal grammar which generates the formal language. Gain and phase parameters of sinusoidal eye movements between a stimulus and its response are computed after the recognition of eye movements and after removing corrective saccades from the transformed signal. The method is used at an otoneurological laboratory.

Diagnosis, Computer-Assisted↗

PubMed1991

Itch and atopic dermatitis: clinical and experimental studies.

The aims of the study were to develop and evaluate methods for quantitative measurement of itch, to investigate the perception of itch in patients with atopic dermatitis (AD), and to measure itch in such patients during treatment with H1-receptor antagonists or cyclosporin A, thereby exploring possible mechanisms in the pathogenesis of itch in AD. In a double-blind, randomized, placebo-controlled, cross-over study of 30 AD patients using a potent, topical, antipruritic corticosteroid, two methods for measuring itch both successfully detected the itch-relieving effect of the corticosteroid. The two methods comprised new portable data-loggers (Pain-Track) for continuous recording of itch, and conventional visual analogue scale (VAS) forms for retrospective recording. The main advantages of the Pain-Track method are possibilities for frequent sampling, surveillance of compliance, and analysis of a large amount of data. Induction and measurement of experimental histamine-induced itch were studied in 38 healthy subjects. It was shown that pruritic stimuli should be presented in a random order so as to avoid systematic errors in the perception of itch. Two rating scales, a seven-stepped non-verbal scale on a Pain-Track logger, and a 100-mm VAS on a potentiometer, were found valid for continuous recording of itch. The perception of experimental itch was studied in 32 AD patients and 32 healthy controls. The itch responses provoked by wool fibres were significantly stronger in AD patients than in controls, whereas the histamine-induced dose-response curves for itch did not differ significantly between the two groups, who discriminated equally well between weak and strong histamine stimuli. No increased skin mast cell releasability was shown in vivo to compound 48/80 in AD patients. Their itch responses to the different pruritic stimuli did not correlate with clinical itch intensity, eczema score or serum IgE-level. In a double-blind, randomized, placebo-controlled, cross-over study of 25 AD patients, the effect on clinical itch of a sedative (clemastine) and of a non-sedative (terfenadine) antihistamine did not differ from that of placebo, although both drugs had a pronounced H1-receptor-antagonizing effect in the skin and clemastine was significantly sedative. These findings support the view that histamine is not the major pruritogen in AD, and that sedation is not necessarily associated with itch relief. In a double-blind, randomized, placebo-controlled, cross-over study of 10 AD patients, 10 days' treatment with cyclosporin A (CSA), 5 mg/kg/day, significantly reduced itch intensity, eczema score and the number of peripheral blood eosinophils.(ABSTRACT TRUNCATED AT 400 WORDS)

Adolescent↗

PubMed1988

Quantitative sensory assessment in toxicology and occupational medicine: applications, theory, and critical appraisal.

Sensory systems are affected by a number of chemicals. Their functions can be quantitatively assessed with psychophysical methods. Psychophysics is the scientific study of the relationship between the physical dimension(s) of a stimulus and the behavioral response it generates. First, the unique contribution of psychophysics to toxicology is illustrated with a few examples taken from the fields of audition, vision, and somatosensory sensitivity. Then, a brief survey of the evolution of psychophysics is presented and followed by a review of its basic scientific foundations. Psychophysical evaluation is accomplished by delivering quantified stimuli in a prespecified order and by requesting a standardized response from the subject. Psychophysical methods specify the sequence of presentation of stimuli, and include the method of limits, the method of constant stimuli, as well as the adjustment and tracking methods. The response paradigms specify the standardized response the subject has to make to stimuli presented according to a specific format. The three major response paradigms are the yes-no, forced-choice, and rating paradigms. Sensory processes can be studied in humans as well as in animals by several techniques, such as classical conditioning, operant behavior, and reflex modulation. A critical review of the application of psychophysical methods and response paradigms is developed. Several examples illustrate the potential confusion brought about by unorthodox use of psychophysical terminology and methodology. Finally, a few suggestions are given for the evaluation of sensory processes in humans.

Animals↗

PubMed1987

Comparison of TRACK XI fluorometric immunoassay system with other serologic tests for detection of serum antibody to Brucella abortus in cattle.

The TRACK XI system (TRACK) is a commercially available fluorometric immunoassay system that has been adapted for the detection of antibodies to several antigens in various animal species. Serum antibodies to Brucella abortus were detected by TRACK and compared with those obtained from two primary binding assays (a fluorometric immunoassay [FIAX] and an enzyme-linked immunosorbent assay) and three standard serological tests (complement fixation, Rivanol precipitation, and CARD tests). A total of 298 serum samples were tested by each serological test. Of these serum samples, 134 were negative controls, 43 were from cattle 1 month after vaccination with B. abortus 19, and 121 were from cattle 10 to 12 weeks after a midgestational, intraconjunctival challenge with B. abortus 2308. The results of this study indicated that TRACK is both reproducible and accurate. The results compared favorably with those of other serological methods. TRACK is more rapid than either the enzyme-linked immunosorbent assay or FIAX system. TRACK was the most sensitive (96.3%) test, with a specificity of 100%.

Animals↗

PubMed1991

Optimal control for the active above-knee prosthesis.

Control of an active above-knee prosthesis has been simulated for a selected gait activity using a hierarchical closed-loop method. An extension of finite-state control, referred to as artificial reflex control, was adopted at the strategic level of control. At the actuator level of control an optimal tracking method, based on dynamic programming, is applied. This deals mainly with the actuator level of control, but considers the interaction of the leg dynamics and the switching effects of artificial reflex control. Optimal tracking at the actuator level of the above-knee prosthesis reduces the on-off effects of finite-state methods, such as artificial reflex control. The proposed method can also be used for the design of prosthetic elements. Specific attention is paid to the limited torque and power in the prosthetic joint actuator, which are imposed by the principle of self-containment in the artificial leg. The hierarchical structure, integrating artificial reflex control and optimal tracking, can be used in real time, as estimated from the number of computer operations required for the suggested method.

Artificial Limbs↗

PubMed1985

A comparison of three speech coding strategies using an acoustic model of a cochlear implant.

Three alternative speech coding strategies suitable for use with cochlear implants were compared in a study of three normally hearing subjects using an acoustic model of a multiple-channel cochlear implant. The first strategy (F2) presented the amplitude envelope of the speech and the second formant frequency. The second strategy (F0 F2) included the voice fundamental frequency, and the third strategy (F0 F1 F2) presented the first formant frequency as well. Discourse level testing with the speech tracking method showed a clear superiority of the F0 F1 F2 strategy when the auditory information was used to supplement lipreading. Tracking rates averaged over three subjects for nine 10-min sessions were 40 wpm for F2, 52 wpm for F0 F2, and 66 wpm for F0 F1 F2. Vowel and consonant confusion studies and a test of prosodic information were carried out with auditory information only. The vowel test showed a significant difference between the strategies, but no differences were found for the other tests. It was concluded that the amplitude and duration cues common to all three strategies accounted for the levels of consonant and prosodic information received by the subjects, while the different tracking rates were a consequence of the better vowel recognition and the more natural quality of the F0 F1 F2 strategy.

Adult↗

PubMed1992

On the feasibility of pulse-echo speed of sound estimation in small regions: simulation studies.

Computer simulations are used to study the feasibility of the estimation of sound speed in small regions with precision better than 1% using the Beam Tracking method. The speed of sound is estimated in a 10-mm by 10-mm region by considering a number of parallel tracks confined to the small region. The transducer focusing and the step sizes for the tracking and tracked transducers required to extract the maximum amount of uncorrelated data from the 10-mm by 10-mm region is evaluated. The results show that the speed of sound can be estimated with error less than 1% in a small region using a typical medical transducer. The statistical comparison of estimates in small areas with different speed of sound is also considered.

Acoustics↗

PubMed1989

[Interactive Microcomputer Method of Lipreading (MIMILLE): an interactive microcomputerized method of lipreading].

A computer-aided speechreading assessment and training system is presented. It is intended to be one component of a comprehensive aural rehabilitation program for preretirement adults with acquired mild-to-moderate hearing loss. Each lesson focuses on a different viseme which is practiced using the 'discourse tracking' method. The system allows the evaluation of the basic skills necessary for lipreading, i.e. good visual speech decoding and effective use of lingustic redundancy and transmitter feedback, by evaluating separately tracking rate, strategy, and types of errors.

Algorithms↗

PubMed1991

The design of CAST (Computer-Aided Speechreading Training).

The underlying theoretical assumptions, goals, design, and implementation of a Computer-Aided Speechreading Training system (CAST) are described as a case study in program design. This computerized speechreading assessment and training system simulates face-to-face intervention and is designed to be one component of a comprehensive aural rehabilitation program for preretirement adults with acquired mild-to-moderate hearing loss. The interactive, automated course consists of eight training lessons, each focusing on a particular viseme that is practiced by a modified discourse tracking method using viseme-specific texts. Three basic speechreading skills are emphasized: visual speech perception, use of linguistic redundancy, and use of feedback between message sender and receiver. These skills are evaluated separately by means of CAST tracking rate, receiver strategy, and inferred error type. Four example case assessments are provided to illustrate the potential applications of CAST as a standardizable rehabilitative tool. An independent program evaluation is provided in a companion paper (Gagné, Dinon, & Parsons, 1991). Comparisons between CAST, face-to-face tracking procedures, and natural discourse are presented and discussed with reference to theoretical and clinical issues in speechreading and program evaluation.

Computer-Assisted Instruction↗

PubMed1989

Abnormal optokinetic and perceptual span parameters in cerebellar-vestibular dysfunction and related anxiety disorders.

As prior studies indicated abnormal cerebellar-vestibular-based sensorimotor mechanisms and neurological and ENG diagnostic parameters in anxiety disorders and because ocular fixation and sequential scanning are cerebellar-vestibular-modulated, it appeared reasonable to measure these and related ocular functions in matched samples of anxiety-disordered and control subjects. In this study, the optokinetically-determined fixation, sequential scanning, and perceptual span capacities obtained by means of a newly revised blurring-speed method were significantly lower or impaired in 70 anxiety-disordered patients vs 70 controls. Such data supported further the hypothesis that there may be cerebellar-vestibular predispositions to anxiety disorders and the optokinetically-based tracking method may prove useful in separating a diverse array of CV-determined or related anxiety symptoms from those of other origins. However, independent validation as well as additional studies of anxiety disorders using larger samples vs random or "normal" controls are required before conclusions are justified.

Adolescent↗

PubMedDate not supplied

Automated local maximum-intensity projection with three-dimensional vessel tracking.

Despite the simplicity and widespread acceptance of the maximum-intensity-projection (MIP) technique for displaying three-dimensional (3D) magnetic resonance angiographic data, several disadvantages are associated with MIP as it is applied to all of the 3D data. These include elevated noise level, reduced contrast between small vessels and background tissue, and the inability to distinguish arteries from veins. The authors have developed a 3D vessel tracking method combined with a local MIP around a given vessel to complement conventional MIP and alleviate these problems. The method is referred to as a traveling MIP (TMIP). TMIP was evaluated in both patients and healthy volunteers. The results indicate that TMIP provides better contrast between vessels and background tissue, better lumen definition, and better vascular visualization than either MIP or vessel tracking alone.

Algorithms↗

PubMed1988

Spatial contrast sensitivity: effects of age, test-retest, and psychophysical method.

Spatial contrast sensitivity was tested twice in normal subjects from five age groups by using each of two different psychophysical methods. Results obtained by the method of adjustment showed a decline in sensitivity with increasing age at all spatial frequencies. In contrast, the forced-choice procedure yielded results indicating an age-related decline predominantly at high spatial frequencies, with the magnitude of the decline being generally similar to that obtained earlier by a tracking method [Vision Res. 23, 689 (1983)]. The decline that we observed cannot be due to pupillary changes with age, since this factor was controlled. Moreover, we suggest that the high-spatial-frequency decline in contrast sensitivity, although it is comparatively small, is too large to be due to changes in lens density. We therefore suggest that a neural component is responsible. In addition, interactions among the age of the subject, the spatial frequency used, and the psychophysical method used suggest that the method of adjustment should be avoided for age-related studies of vision.

Adult↗

PubMed1989

Conformation therapy to improve the irradiation of the spinal axis.

Techniques for the irradiation of the spine have remained largely unchanged since the introduction of megavoltage therapy. The main disadvantages of these techniques are the inhomogeneous dose distribution and the problems associated with field joins. The tracking method of conformation therapy employs a short field length and translates the patient through the beam on the couch of a computer controlled treatment unit. Dose uniformity along the spinal axis is achieved by controlling the speed at which the target travels through the radiation field. Treatment is given at standard source-axis distance (SAD) and the need for external shielding is eliminated by shaping the width of the field. The join with the cranial fields is independent of any skin marks, removing the risk of over- or under-dosage. Treatments are planned automatically from computed tomography (CT) information by an in-house planning system. The calculated doses have consistently shown good agreement with phantom measurements. Three cobalt dose distributions are presented and compared: a tracking treatment; a single posterior field, and two matched fields. The superiority of conformation therapy over the other commonly used treatment methods is clearly demonstrated.

Humans↗

PubMedDate not supplied

Pulse wave recording--development of a method for investigating foetal circulation in utero.

The need to investigate the elastic properties of arterial vessels 'in situ' for the early recognition of degenerative disorders in arteries has long been apparent. Volume pulses in defined segments of arteries can be evaluated for this purpose, and the present paper contains a survey of earlier attempts to quantify volume pulses by means of ultrasound. A presentation is given of a recently developed digital system, comprising a phase-locked echo tracker, capable of monitoring non-invasively the diameter and its pulsatile changes of a selected artery along two chosen image lines of a linear array ultrasound scanner. The physical limitations of tracking fast-moving ultrasound echoes by means of phase-locked range gating are reported and the advantage is emphasized of using a gate length of one full period. This system has been calibrated, tested and applied in measurements of pulse wave pattern and propagation velocity in the descending aorta of human foetuses in the last trimester of gestation. The present high-resolution echo-tracking method has yielded reproducible results in the foetus and appears suitable also for screening studies on adult vessels.

Blood Circulation↗

PubMed1987

Quantification of blood pressure tracking of children by tracking index: the Shimane Heart Study.

The tracking of systolic blood pressure (SBP) was analyzed in a cohort of children. The study population consisted of 1009 Japanese children in Izumo City, a rural community in the northwest of Honshu. There were 252 subjects in cohort (C)-1, 235 in C-2, 286 in C-3, 131 in C-4 and 105 in C-5. Follow-up periods were from 6 to 9 years of age in C-1, 9 to 12 in C-2, 12 to 15 in C-3, 6 to 12 in C-4 and 9 to 15 in C-5. BP was measured by conventional method. Tracking index (TI) was calculated as follows: TI = (2x + y - z)/N/.24; x, y and z are numbers of subjects who remained at the same quintile, who moved to the next quintile and who moved to a remote quintile, respectively; N = x + y + z; TI becomes 1.0 when SBP changes randomly. SBP tracking was apparent in both sexes of C-1 (TI = 2.4 in boys, 2.5 in girls), in girls of C-2 (TI = 3.5), in both sexes of C-3 (TI = 3.2 in boys, 2.7 in girls) and in girls of C-4 (TI = 4.1) and C-5 (TI = 3.3). TI agreed well with the tracking phenomena visualized by distribution bar graph. We conclude that TI can assess the degree of tracking quantitatively and can be applied to analysis of the tracking phenomena of BP and its related factors.

Blood Pressure↗

PubMed1990

Motion of individual human spermatozoa, both normal and lacking the outer dynein arms, during a continuous temperature rise.

The effect of increasing temperature from 22-25 degrees C to 37 degrees C on various motion characteristics of individual normal human spermatozoa and spermatozoa lacking the outer dynein arms (LODA) was studied by using a new automatic microscopic tracking method. It was found that: 1) The curvilinear velocity (Vc, measured between 1-3 sec) of both normal and LODA spermatozoa, fluctuated more or less intensely between spermatozoa; this fluctuation was not thermodependent. 2) The average Vc in the two groups of spermatozoa increased with the rise in temperature at a similar rate (1 micron/sec/degrees C), but LODA spermatozoa had an initial Vc lower than that of normal spermatozoa (12.5 +/- 5.3 microns/sec and 34.2 +/- 8.2 microns/sec, respectively). 3) The profile of the Vc increase associated with the temperature rise was different for the two groups of spermatozoa: for LODA spermatozoa it was linear between 25-37 degrees C, whereas for normal spermatozoa a plateau was reached at about 31 degrees C. 4) Various patterns of trajectory were found for both normal and LODA spermatozoa; these patterns were unrelated to temperature. However, LODA spermatozoa had more linear trajectories than normal spermatozoa. 5) Plots derived from reaction rate theory showed that the activation enthalpy, delta H was a function of the increase of Vc for both normal and LODA spermatozoa, but that delta H was higher for LODA spermatozoa.

Adenosine Triphosphatases↗