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PubMed1990

In vitro pharmacologic separation of corneal endothelial migration and spreading responses.

Repair of corneal endothelial wounds involves two forms of cell translocation: (1) "migration," in which individual cells at the wound edge break contacts with neighboring cells and move as individuals into the wound defect, and (2) "spreading," in which cells within the confluent monolayer adjacent to the wound move as a group into the wound area. The authors combined morphometric analysis of Giemsa-stained cultures, phase-contrast video microscopy, and Rh-phalloidin staining of actin filaments to study the effects of epidermal growth factor (EGF) and indomethacin on the migratory and spreading responses to wounding using an in vitro wound-closure model which mimics the amitotic state and general behavior of human corneal endothelium. They found that EGF stimulated the migration of individual cells from the wound edge, induced cellular elongation, and promoted a diffuse distribution of actin filaments. Indomethacin promoted spreading of the confluent monolayer into the wound defect, induced enlargement and flattening of cells, and promoted the formation of long, thick actin stress fibers. These results provide evidence that the migration and spreading responses of corneal endothelial cells to wounding can be pharmacologically separated. The findings suggest that migration of individual cells during wound repair may result from an endogenous form of EGF-like stimulation and that the elongated shape associated with this form of translocation results, at least in part, from an EGF-like alteration in actin-filament organization. Spreading of the confluent monolayer to cover the wound defect may result from a decrease in cyclic adenosine monophosphate induced by a transient reduction in prostaglandin E2 synthesis. This form of translocation may result, in part, from enlargement and flattening of corneal endothelial cells secondary to an enhancement of actin stress-fiber formation.

Actins↗
PubMed1990

A study of variance in densitometry of retinal nerve fiber layer photographs in normals and glaucoma suspects.

The main object of this research was to develop a reliable method of screening glaucoma suspects and patients for early loss of or changes in the retinal nerve fiber layer (RNFL). This study quantifies the variances due to photography, digitizing, and analysis of red-free photographs of the RNFL. The influence of pupil size, optic disc position and eye movements, film processing, digitizing, and intra- and interphotographic-session and intra- and interoperator variances were established. It was found that pupils needed to be dilated to at least 6 mm, that the optic disc had to be positioned in a standardized area in the negative, that the head of the subject had to remain still during photography, and that film processing and digitizing of the negative needed to be strictly controlled to minimize the variance in collection of densitometry data from RNFL red-free photographs. It was established that focusing of the negatives during digitization was not crucial. Criteria were defined for acceptable negatives. Interphotographic-session and intraoperator variances were not significant in most cases when negatives were digitized to these criteria. Analysis of interphotographic-session variance showed that there were still some factors in photography, film processing, and/or image digitizing that were not sufficiently controlled for long-term follow-up without normalization of the data. Densitometry data gathered using the established protocol, from negatives of 71 subjects were analyzed; best sensitivity and specificity rates of 80% and 100%, respectively, were achieved for the diagnosis of glaucoma.

Adult↗
PubMedDate not supplied

Corneal steepening in human eye bank eyes by combined hexagonal and transverse keratotomy.

An interrupted 5 mm diameter hexagonal keratotomy was modified to include six paracentral transverse incisions to augment the central corneal steepening. This combined modified-hexagonal and transverse (or hexagonal-transverse) keratotomy was performed on human eye bank eyes to an estimated 85% corneal depth yielding a mean of 7.50 +/- 1.69 diopter increase in central keratometric power (P less than .001); this finding was confirmed by keratography. These results encourage further studies of this procedure and its potential to surgically correct mild amounts of hyperopia.

Analog-Digital Conversion↗
PubMed1990

Determination of peak-ratio by digital turns-amplitude analysis on line.

In a previous study the peak-ratio of turns to mean amplitude of the EMG interference pattern obtained from tape recordings identified 80% of patients with myopathy. In order to obtain the peak-ratio during the examination using the mean amplitude as an indication of force a digital turns-amplitude computer with a TMS 320/10 digital signal processor was developed. The EMG was analysed with a 12 bit resolution and a sampling rate of 100 kHz. In 492 samples from the brachial biceps muscle of controls, patients with myopathy and neuropathy, the digital method gave about the same turns-amplitude values as the analogue analyser. Control material for on line analysis of the peak-ratio was obtained in the brachial biceps, the abductor pollicis brevis, the medial vastus and the anterior tibial muscles of 20 subjects.

Adolescent↗
PubMedDate not supplied

Design of a microprocessor-based sphygmomanometer.

This paper describes the implementation on a microprocessor of a new method for the indirect measurement and recording of the systolic and diastolic blood pressure in humans. The technique is based on a statistical analysis of the cardiac pulse pressure signal. Polynomial relations are derived between the amplitude of the pulsatile pressure waveforms at the systolic and diastolic points and the amplitude of pulse signals detected when the artery is fully occluded. With the dual objective of automating the measurement procedure and minimizing errors, an electronic analog-digital sphygmomanometer that contains suitable electronic instrumentation was developed. The functions of processing the pressure signal, automating the measurement, and recording the results are performed and controlled by a microprocessor. A laboratory prototype embodying this approach was constructed and its performance and reliability were verified using a series of clinical tests. The test results indicate that the device is accurate within acceptable bounds for automated blood pressure instruments.

Analog-Digital Conversion↗
PubMedDate not supplied

Human sperm motion analysis by automatic (Hamilton-Thorn Motility Analyzer) and manual (Image-80) digitization systems.

Two systems allowing quantitative, objective analysis of sperm movement were compared: 1) the Hamilton-Thorn Motility Analyzer (HTM), in which sperm images are digitized automatically, and 2) the Image-80, a modified image-analysis system in which sperm movement is digitized manually by hand tracing from videotape (Tessler and Olds-Clarke, 1985). Videotapes were made of human spermatozoa obtained by a swim-up procedure. The same videotape frames were analyzed by both systems. The mean percentage of motile spermatozoa was similar as judged by eye with either the HTM or Image-80 monitors and as reported by the HTM. For every motile spermatozoon, two motility parameters were calculated: linearity (a measure of track shape) and curvilinear velocity at 30 frames/second (a measure of track speed). When samples from five donors were averaged, there were no significant differences in mean linearity between automatic and manual systems. Also, linearity as reported by the HTM and Image-80 systems for the same track was significantly correlated (r = 0.72; N = 80). Whereas the absolute values for curvilinear velocity were slightly but significantly higher for the Image-80 system than for the HTM system, their correlation was also significant (r = 0.91). Since the two systems provide comparable data on percentage of motile sperm as well as speed and path shape parameters, this suggests that the HTM automatic digitization is accurate for images of human spermatozoa.

Adult↗
PubMed1990

Digital processing of equine exercise electrocardiograms.

We have developed and used a system for recording and analyzing the electrocardiogram (ECG) of the horse during exercise. The system consists of a commercial ECG transmitter telemetering a Z lead (base-apex) ECG from an exercising horse. The received data are then remodulated at an audio frequency and stored on a audio cassette recorder. Exercise protocols of up to 10 minutes are digitized using a Macintosh II computer. For rhythm analysis, a computer program to identify the various waves of the ECG uses a modification and refinement of the integrated-squared-derivative (ISD) technique. This technique consists of frequency selective digital filtering and differentiation followed by integration of the squared derivative. The waves of the ECG are identified using adaptive thresholding of the ISD and the derivative of the ECG. Thus far, we have been able to successfully identify the Q, R, and the end of T in ECGs severely contaminated by exercise artifact. The system can place the absolute time of occurrence of the Q, R, and end of T in a text file for export to other analysis programs such as spreadsheets and statistics packages.

Algorithms↗
PubMed1990

A software package for event related potential experiments.

All too frequently, researchers find that experimental designs are dictated by procedures implemented by the available equipment rather than by the questions to be answered. Event related potential experiments are limited by equipment which restricts the type and number of stimuli which can be presented and the length, number, and type of averages which can be computed. A software package was developed for event related potential experiments which provides a high degree of flexibility in designing the stimulus presentation protocol and the averages which can be computed. The package includes a set of user friendly programs for constructing complicated stimulus presentation sequences. In order not to restrict the researcher to a set of predetermined averages computed at the time the experiment is conducted, the EEG data is digitized and stored continuously without regard to times of stimulus presentation. Averages are computed from the continuous EEG data by a separate averaging program which takes as input a table of starting times of the segments to be averaged. The software package is currently in use at Dr. Rohrbaugh's laboratory for a series of complicated event related potential experiments.

Analog-Digital Conversion↗
PubMed1990

Forty hertz (40Hz) and sensorimotor rhythms (SMR) as EEG state variables and related evoked potentials.

There is evidence that certain brain rhythms may signal the occurrence of different brain states. Support for this hypothesis may be provided by evidence that processing of information is changed during different brain states. The prestimulus period proceeding the auditory evoked potential (AEP) is converted to a power spectral estimate. These power spectra are used to sort for the AEP when certain power values for the (36-42Hz) and the (11-16Hz) are reached in the prestimulus period of the sensory motor cortex, nucleus accumbers and amygdala. Attempts are made to measure the performance of the 40Hz and SMR estimators. These studies are made in the cerebral cortical and subcortical regions in cats. In these studies D and L isomers of amphetamine are used to induce a chemical brain state changes. The AEP are selected in the amphetamine altered states based on the prestimulus auto spectra.

Analog-Digital Conversion↗
PubMed1990

Multi-programmable hearing aid.

A basic problem in hearing-aid fitting is the difficulty in finding one setting optimal to all listening situations that might occur. The objective was to develop a behind-the-ear hearing-aid with a very flexible analog signal processor which is digitally controlled, and a memory with logic, so that the hearing-impaired person can select from eight completely different fittings. To program and adjust this multi-programmable hearing-aid (called MemoryMate) a hearing evaluation and recommendation system (called Master-Fit) has been developed, based on an IBM PS/2 computer. This system offers the dispenser prescriptive fitting methods and performance of real ear measurements. It can be used to manage a client database. Preliminary results from a clinical study conducted in 1988 are presented. The paper also describes the uniqueness of this multi-programmable hearing aid as a powerful new research tool.

Aged↗
PubMed1990

Quasi-dynamic test of in vitro cell migration developed to characterize dividing cells of spontaneously metastasizing rat sarcomas.

A "Quasi-dynamic Test of in vitro Cell Migration" (QTCM) was developed in which the quantitative estimation of migration of dividing cells is based on a comparative evaluation of their dispersion in single-cell-derived colonies after 72 h of clonal growth under standard and test conditions. Expert visual evaluation of microscopic images of cell colonies including estimation of dispersion of cells in the colonies is checked and made more precise by computerized evaluation of digitized outlines of cells in the colonies. Using QTCM, distinctions in the pattern of migration between three neoplastic cell populations differing by their origin and degree of malignancy were found. Although transfer of cells into slightly acid conditions did not always increase the mean value of cell dispersion in the colonies, each cell population was found to include a cell fraction that did manifest considerably greater migration and this fraction was markedly larger in the more malignant cell populations. The results of both types of evaluation, visual and computerized, were in mutual accord, with accuracy being greater on the computer side. Thus, the QTCM proved useful for qualified estimation and/or computer measurement of in vitro migration of dividing cells on a population level.

Analog-Digital Conversion↗
PubMedDate not supplied

Poor man's VTO.

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Analog-Digital Conversion↗