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At least 541 records · Page 30Linked to original sources

PubMed1995

Kinematics of capacitating human spermatozoa analysed at 60 Hz.

Hyperactivation is a concomitant of eutherian sperm capacitation, characterized by the development of high amplitude flagellar waves with a corresponding increase in velocity. In humans, kinematic values have been derived which describe the movement characteristics of spermatozoa analysed at 30 images/s. However, these values are frame rate-dependent, and modern computer-aided sperm analysis (CASA) instruments used for studying sperm movement now use 60 images/s. This study used first-principles manual track analysis to derive the range of movement characteristics which describe hyperactivated motility of human spermatozoa at 60 images/s. Standard terminology for centroid-derived movement characteristics, as recommended by the World Health Organization, was used. US-standard (NTSC) video recordings of capacitating human sperm populations were replayed using a non-interlaced freeze-frame video cassette recorder, and individual tracks reconstructed on acetate overlays. Tracks were classified as either forward progressive or hyperactived based upon flagellar beating patterns, then reconstructed manually at x3540 and analysed using both manual methods and basic geometric calculations from (x, y) coordinates (Cartesian methods) similar to those used by CASA instruments. In all, 40 hyperactivated and 40 forward progressive tracks were studied. A set of Boolean arguments defining hyperactivated motility was derived, and there was generally good agreement between the limits derived by manual and Cartesian methods. The limits for the definition of hyperactivated motility of human spermatozoa at 60 Hz derived by Cartesian methods were: curvilinear velocity > or = to 180 micrograms/s and linearity < or = to 45% and wobble < 50% and amplitude of lateral head displacement ALHmean > 6.0 micrograms or ALHmax > 10.0 micrograms.(ABSTRACT TRUNCATED AT 250 WORDS)

Humans↗

PubMed2006

Observing decision-making in the general practice consultation: who makes which decisions?

OBJECTIVE: To investigate opportunities for, and types of decision making in the general practice (primary care) consultation, and examine differences in skills of those doctors who are successful at meeting their patients' preferences and those who are less successful. DESIGN: Observation study of doctor-patient consultations in general practice. PARTICIPANTS: Patients attending for routine appointments in 12 general practice surgeries across Oxfordshire. METHODS: A total of 212 doctor-patient consultations were video-recorded. The patients involved completed a questionnaire to elicit their perceptions of how decisions were made. The video-taped recordings were coded with a new instrument, the Evidence Based Patient Choice Instrument (EBPCI), to classify the number and type of decision-making opportunities arising during each consultation. A total of 149 recordings were coded using the Oxbridge Rating Scale to assess the doctors' consultation styles. RESULTS: There was a range of decision-making opportunities in addition to those involving medical treatment. With the exception of 'fitness for work', decisions were generally 'doctor led'. There was only moderate agreement between patient perceptions of their level of involvement in decision making and the objective ratings using the EBPCI. There was wide variation in the ability of doctors to meet their patients' preferences for involvement. CONCLUSIONS: There are many decisions made in primary care consultations, in addition to those about medical treatments, in which patients could be involved to a greater extent than they currently are. Some doctors are significantly better than others at meeting different patients' preferences for their decision-making role. Patients' perceptions of shared decision making appears to be influenced by the doctors' general consultation skills.

Adult↗

PubMedDate not supplied

Quantification of ciliary beat frequency in sinonasal epithelial cells using differential interference contrast microscopy and high-speed digital video imaging.

BACKGROUND: Mucociliary clearance is a critical upper airway host defense mechanism. Ciliated epithelium in the mammalian airway continually beat at a baseline frequency. Importantly, during times of stress such as exercise or infection, the cilia beat faster to increase clearance. Nasal epithelial ciliary beat frequency (CBF) has been analyzed previously in ex vivo specimens using a variety of methods including photodiode detectors and conventional video recording. Recent studies performed using lower airway ciliated mucosa have shown poor correlation between CBF quantified by photodiode/conventional video and those using high-speed digital video capture at temperatures close to physiological temperatures. Thus, to more rigorously interrogate sinonasal CBF at physiological conditions, we have incorporated a high-speed digital video camera to our CBF analysis system. This is the first report of sinonasal epithelial CBF analysis performed using high-speed video digital analysis. METHODS: Ex vivo samples of sinonasal epithelium were placed in lactated Ringer's in a temperature-controlled microscope stage chamber. An edge of tissue containing beating cilia was observed at a magnification of 630x using differential interference contrast microscopy. The images were captured using a high-speed digital camera with a sampling rate of 250 frames per second. CBF was determined using computerized data analysis. RESULTS: The mean nasal CBF was calculated from a minimum of five regions for each sample. Temperature curves were generated from tissue obtained from chronically infected subjects. CONCLUSION: Analysis of high-speed digital video capture of sinonasal CBF observed under differential interference contrast microscopy is a powerful method to investigate environmental as well as host influences on mucociliary clearance within the upper airways.

Cilia↗

PubMed1977

The use of video-tape techniques in the psychiatric training of family physicians.

This paper describes the use of video-tape techniques in the training of family physicians. Some general objectives for the psychiatric curriculum for family medicine training programs are enumerated. The implementation of these goals include (1) development of a library of video recordings which contain illustrative examples of psychiatric syndromes and management problems that appear frequently in family practices; and (2) use of video-tape recordings of the trainee during routine medical encounters and during counseling sessions for later review with supervising faculty. Some specific examples are cited of what to look for in the medical encounters and of how the video tape allows faculty to be more concrete in their instruction.

Curriculum↗

PubMed2000

Low-cost video-films in the teaching of undergraduate and postgraduate medical students.

The high cost of producing good-quality video-films for teaching has hindered the use of this method, which has been shown to improve significantly the efficiency of teaching and the retention of knowledge. During the last five years, a series of short video-films has been produced using inexpensive video-cameras and home video-recording and editing equipment. A variety of techniques were developed to allow recording of lecture presentations, while using the equipment as a teaching aid, without the need for technical staff. The positioning of the camera, the monitor, the slide projector and lighting were critical to the productions. Similar productions at low cost were obtained from recordings of operating theatre sessions, tutorials and clinical ward rounds. A survey of students exposed to teaching with video-film as part of a lecture presentation confirmed that the subject matter being taught was more easily understood and enjoyable and generated more discussions on than other forms of teaching.

Education, Medical, Graduate↗

PubMed1999

A study of the measurement errors associated with the analysis of velar movements assessed from lateral videofluoroscopic investigations.

OBJECTIVE: The analysis of lateral videofluoroscopic images of velar movements during speech is a commonly used tool in the management of the cleft palate patient. This study tests the general hypothesis that measurements of velar movements taken from lateral videofluoroscopic images are accurate and reliable. METHOD: A measurement system was used that allowed for the rapid assessment of velopharyngeal distance, soft palate velocity during the closure cycle, extension of the soft palate at maximum closure, and the angular lift of the soft palate above the plane of the hard palate. Ten recordings of soft palate movement during speech were randomly chosen from lateral X-rays of 27 normal adults. The video recordings were captured by digital frame grabber for subsequent analysis by three operators using a standard PC that was running image-analysis software. The uncertainties associated with the above measurements were analyzed in terms of the errors introduced by the inherent calibration and nonlinearity of the imaging system, the inaccuracy of the patient setup, and the operator-dependent measurement error. RESULTS: For both absolute dimensions and ratiometric measurements, the measurement uncertainties related to the inherent nonlinearity in the imaging system were shown to be less than 2%. Typical patient misalignments as a result of a 10 degree head rotation and a 10-mm translation out of the measurement plane introduced errors of between 2% and 3%. Results showed that the average standard deviation for measurement of gap size was 1.2 mm, extension ratio was 0.11, angular lift was 3.1 degrees, and soft palate velocity was 15.5 mm/second. The intra-class correlation coefficient generally showed a good agreement between operators, typically in the range 0.8 to 0.9. CONCLUSION: Measurements of velopharyngeal distance, extension of the soft palate at maximum closure, and the angular lift of the soft palate above the plane of the hard palate assessed from lateral videofluoroscopic images are reliable and accurate. The soft palate velocity during the closure cycle can also be determined, but clinical interpretations based on this parameter should be constrained by the measurement uncertainties.

Adult↗

PubMed2005

A method for the validation of a new calculus detection system.

BACKGROUND: Recently, pilot studies from our laboratory have shown that dental surfaces may be discriminated by the analysis of tip oscillations of an ultrasonic instrument, which possesses computerized calculus-detection features. For the evaluation of this smart detection system, its surface recognition qualities are of crucial importance. For in vivo studies, however, it proved to be difficult to verify the subgingival detection results. Therefore, it was necessary to develop a method, which allowed a reliable validation of surface recognition results of this new device. This evaluation method is described here. MATERIALS AND METHODS: Thirty extracted human teeth with subgingival calculus were embedded with plaster in a tray. To simulate subgingival pockets, dissected mucoperiostal porcine gingiva was sutured on the teeth. The thus-constructed dentition was mounted into a phantom head. A CCD-cam was attached with an intra-oral X-ray mount to the teeth. The dentist scanned the pockets with the ultrasonic instrument, simultaneously videotaping the scanning path of the supragingival portion of the insert. At the same time, the signals of the modified ultrasound scaler were recorded. After the tooth was removed from the phantom head, the tip of the ultrasound scaler could be repositioned using the video sequences. The actual insert location on calculus or cementum was assessed and compared with the computer signals. The whole procedure was repeated a second time and the reproducibility of the evaluation method was estimated. RESULTS: A kappa value of 0.95 was attained for the evaluation method. CONCLUSION: The present experimental design allows the in vitro repositioning of an automated dental instrument for the detection of subgingival surfaces on the tooth following an in vitro phantom-head video recording of its intra-oral scanning movements. This method will be used for the verification of in vivo results of a new ultrasound-based surface detection system.

Algorithms↗

PubMed2003

Technical note: Validation of a system for monitoring feeding behavior of dairy cows.

An electronic system has been designed that allows for passive monitoring of feeding behavior of individual cows housed in a free-stall barn. The objective of this study was to validate the data generated by this GrowSafe feed alley monitoring system. Twelve lactating cows were each monitored for 24 h using both the GrowSafe system and time-lapse video. The GrowSafe estimation of number of meals consumed by each cow showed perfect agreement with meal frequency identified using the video recordings. The duration of these meals, as estimated by GrowSafe, was highly correlated with the meal duration derived from the video (R2 = 0.98). Despite the excellent agreement for these meal-based measures, for each cow we found some instances in which the video showed that a cow was present at the feed alley but GrowSafe failed to detect cow presence (12.6% of observations) and a few instances in which the reverse was true (3.5% of observations). However, all the missed or extraneous data from the GrowSafe system were closely associated in time with known periods of feeding. These results indicate that this feed alley monitoring system can provide very good measures of meal frequency and meal duration and reasonable estimates of instantaneous feed alley attendance for loose-housed dairy cattle.

Animals↗

PubMed1993

High-speed, light-intensified digital imaging of vocal fold vibrations in high optical resolution via indirect microlaryngoscopy.

Digital imaging of vocal fold vibrations is mainly limited by lighting problems. We present a new technique for high optical resolution of vocal fold vibrations (via indirect microlaryngoscopy) using a light intensifier camera. Superficial epithelial structures and secretions can be followed during vibrations by means of high magnification. Recordings of up to 2.4 seconds and 6,000 frames per second, combined with simultaneous recording of acoustic and electroglottographic signals, are possible. This technique allows instant slow-motion monitor control and subsequent documentation on a normal video recording system. We also present preliminary findings of typical vocal fold motion patterns.

Female↗

PubMed1990

Eye movement analysis system using computerized image recognition.

A new technique for an eye movement analysis system utilizing infrared video recording and a computerized image recognition method is presented. The system consists of an infrared lighting apparatus, a very small infrared video charge-coupled device camera, a video tape recorder, an analogue-digital converter, and microcomputers. This system makes it possible to simultaneously analyze the slow-phase velocity quantitatively not only of the horizontal and vertical but also of the rotatory components of the energy-induced nystagmus. The maximum slow-phase velocity of the rotatory component of energy-induced nystagmus was found to be 4.1 degrees per second on an average in this study.

Adult↗

PubMed1993

In situ hybridization on May-Grünwald Giemsa-stained bone marrow and blood smears of patients with hematologic disorders allows detection of cell-lineage-specific cytogenetic abnormalities.

Bone marrow and blood from patients with acute myeloid leukemia and myelodysplastic syndrome were studied by simultaneous analysis of cell morphology and karyotype. A combined technique of May-Grünwald Giemsa (MGG) for cell morphology and fluorescence in situ hybridization (FISH) with chromosome-specific DNA probes for detection of cytogenetic aberrations allowed us to investigate cell-lineage-specific chromosomal abnormalities. We introduced video recordings to examine large numbers of cells. Briefly, evaluation was first performed on MGG slides, during which cell position and morphology were recorded on an S-VHS recorder. Subsequently, the same slides were used for FISH. This resulted in the identification of MGG-stained cells on the video screen and, at the same time, the interpretation of FISH signals in the fluorescence microscope. Specimens of bone marrow or blood samples from four patients with different hematologic malignancies were studied. One of these patients was studied before and after cytotoxic treatment. The gain or loss of chromosomes could be detected easily and morphologically assigned to the blasts in all patients and to a variable proportion of the myelomonocytic lineage in two patients, but not to the lymphocytes. Thus, this method provides new possibilities for investigating the clonality of hematologic malignancies.

Acute Disease↗

PubMedDate not supplied

Digital image capture and quantification of subtle lens opacities in rodents.

A rapid, sensitive, and cost-effective method is reported for the subjective and objective documentation of subtle opacities in lenses of unanesthetized transgenic mice or selenite-injected rat pups as models for cataract formation. Animal eyes were dilated with eye drops and the animal was positioned in front of a Nikon FS2 photo slit lamp. Slit-lamp observations were recorded using a Canon Optura Pi digital video recorder. High-quality images of opacifying lenses were captured from the video and quantified using densitometry at progressive stages of opacification. In mice, targeted genomic deletion of the proteins CP49 (a lens-specific filament) or Six5 (a model for myotonic dystrophy) resulted in subtle cataracts that were easily recorded and quantified using this instrumentation. In rats, the early progressive changes leading to a dense nuclear opacity caused by selenite injection were easily documented using this instrumentation. Low-cost components combined with a conventional slit-lamp ophthalmoscope were used to capture high-quality images of selected stages of cataract formation for quantitative analysis using commercial software.

Animals↗

PubMed1998

A video data base system for studying animal behavior.

Classification of farm animal behavior is based on oral or written descriptions of the activity in which the animal is engaged. The quantification of animal behavior for research requires that individuals recognize and code the behavior of the animal under study. The classification of these behaviors can be subjective and may differ among observers. Illustrated guides to animal behavior do not convey the motion associated with most behaviors. Video-based guides offer a method of quantifying behaviors with real-time demonstrations of the components that make up a behavior. An animal behavior encyclopedia has been developed to allow searching and viewing of defined (video-recorded) behaviors on the Internet. This video data base is being developed to initiate a system that automatically extracts animal motion information from an input animal activity video clip using a multiobject tracking and reasoning system. Eventually, the extracted information will be analyzed and described using standard animal behavior definitions (the behavior encyclopedia). The intended applications of the behavior encyclopedia and video tracking system are 1) an accessible data base for defining and illustrating behaviors for both research and teaching and 2) to further automate the collection of animal behavior data.

Animals↗

PubMed2006

Establishing a gold standard for manual cough counting: video versus digital audio recordings.

BACKGROUND: Manual cough counting is time-consuming and laborious; however it is the standard to which automated cough monitoring devices must be compared. We have compared manual cough counting from video recordings with manual cough counting from digital audio recordings. METHODS: We studied 8 patients with chronic cough, overnight in laboratory conditions (diagnoses were 5 asthma, 1 rhinitis, 1 gastro-oesophageal reflux disease and 1 idiopathic cough). Coughs were recorded simultaneously using a video camera with infrared lighting and digital sound recording. The numbers of coughs in each 8 hour recording were counted manually, by a trained observer, in real time from the video recordings and using audio-editing software from the digital sound recordings. RESULTS: The median cough frequency was 17.8 (IQR 5.9-28.7) cough sounds per hour in the video recordings and 17.7 (6.0-29.4) coughs per hour in the digital sound recordings. There was excellent agreement between the video and digital audio cough rates; mean difference of -0.3 coughs per hour (SD +/- 0.6), 95% limits of agreement -1.5 to +0.9 coughs per hour. Video recordings had poorer sound quality even in controlled conditions and can only be analysed in real time (8 hours per recording). Digital sound recordings required 2-4 hours of analysis per recording. CONCLUSION: Manual counting of cough sounds from digital audio recordings has excellent agreement with simultaneous video recordings in laboratory conditions. We suggest that ambulatory digital audio recording is therefore ideal for validating future cough monitoring devices, as this as this can be performed in the patients own environment.

Journal Article↗

PubMed1998

Variability in the skin exposure of machine operators exposed to cutting fluids.

OBJECTIVE: This study describes a new technique for measuring skin exposure to cutting fluids and evaluates the variability of skin exposure among machine operators performing cyclic (repetitive) work. METHODS: The technique is based on video recording and subsequent analysis of the video tape by means of computer-synchronized video equipment. The time intervals at which the machine operator's hand was exposed to fluid were registered, and the total wet time of the skin was calculated by assuming different evaporation times for the fluid. The exposure of 12 operators with different work methods was analyzed in 6 different workshops, which included a range of machine types, from highly automated metal cutting machines (ie, actual cutting and chip removal machines) requiring operator supervision to conventional metal cutting machines, where the operator was required to maneuver the machine and manually exchange products. RESULTS: The relative wet time varied between 0% and 100%. A significant association between short cycle time and high relative wet time was noted. However, there was no relationship between the degree of automatization of the metal cutting machines and wet time. CONCLUSIONS: The study shows that skin exposure to cutting fluids can vary considerably between machine operators involved in manufacturing processes using different types of metal cutting machines. The machine type was not associated with dermal wetness. The technique appears to give objective information about dermal wetness.

Adult↗

PubMed1998

Direct measurement of intraparticle fluid velocity in superporous agarose beads.

Superporous agarose beads contain both normal diffusion pores and special, very wide superpores through which part of the chromatographic flow is transported, a situation that may greatly improve the chromatographic performance. For the first time such pore flow was measured directly by following the movement of microparticles (dyed yeast cells) through superporous beads packed in a chromatographic bed. The passage of the microparticles through the superpores and through the interstitial pores was recorded by a microscope/video camera. The video recordings were subsequently used to determine flow paths as well as the convective fluid velocities in both the superpores and the interstitial pores. The superpore fluid velocity was found to be proportional to the ratio between the squares of the respective pore diameters, which is in agreement with the Kozeny-Carman equation. Values for two-dimensional and three-dimensional tortuosity of the flow paths were measured and calculated respectively.

Chromatography, Agarose↗

PubMed1989

Dynamics of the Golgi method: a time-lapse study of the early stages of impregnation in single sections.

This paper describes the early stages of impregnation by the Golgi method. Sections of aldehyde-fixed and potassium dichromate-treated cerebral cortex were mounted on glass slides and cover slipped. The dichromate solution was replaced by silver nitrate solution and events in the section were followed and recorded by time lapse microphotography and video recording until stopped by replacement of silver nitrate solution by glycerol. The sections were subsequently prepared for electron microscopy (EM) study. In sections about 2 x 2 mm and 100 microns thick a fine, dark granular precipitate formed at the edges within the first minutes of exposure to silver nitrate and a wave of brownish colouration spread to a depth of about 0.3 mm. After approximately 7 min, shrub-like focal precipitates (nucleation centres) appeared in the sections. From these nucleation centres (but also from the section edges) thread-like 'outgrowths', usually identified as dendrites, spread into somata. Sometimes impregnation began within the soma and spread into dendrites. The rate of impregnation (i.e., of silver chromate deposition within dendrites) was typically 1-7 microns min-1, faster in the earlier stages (up to 3 microns s-1) and very slow after 30 min, by which time many neurons were more or less fully impregnated. The dimensions of the section, the width of an agar frame around the sections, and the frequency with which the silver nitrate in the sections was replenished all affected the extent and time course of the impregnation. By EM the earliest intracellular deposits consisted of tubulolamellar formations which did not cross plasma or endocellular membrane boundaries and which contained irregularly shaped and scattered granules, initially about 10 nm in diameter. The latter progressively enlarged and coalesced as the tubulolamellar formations extended, eventually to fill the cross-sectional area of neuronal processes and cell bodies. These observations shed light on why so few neurons become impregnated with the Golgi method. Impregnation occurred only in those cells a part of which was within a nucleation centre.

Animals↗

PubMed2005

A markerless sub-pixel motion estimation technique to reconstruct kinematics and estimate the centre of mass in posturography.

A novel method to evaluate postural sway is presented: balance strategies are identified by applying a markerless image processing algorithm to video sequences obtained from commercially available systems. The motion estimation technique for the analysis of video sequences is a coarse to fine procedure based on the block matching algorithm (BMA). The method makes it possible to estimate the movement of selected elements on the scene with a sub-pixel precision. It has been done by applying a bicubic spline interpolation to the coarse results obtained by the BMA. Results achieved through the analysis of synthetic video tests make it possible to determine the accuracy of the proposed sub-pixel algorithm. Figures show how the proposed method can be confidently applied to evaluate postural sway. The proposed method has been applied to videos recorded during orthostatic posture trials in different conditions, and to combined tests where signals from a balance plate have been acquired simultaneously to the video sequence. The results show the usefulness of the proposed approach in order to evaluate balance strategies in posturography.

Algorithms↗