SEARCH · PubMed Health

Results for “Video Recording”

Explore indexed PubMed citations for clinical trials, systematic reviews and public health research. Read source abstracts and follow each citation to its original PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 1,135 records · Page 63Linked to original sources

PubMed1984

A moving video window or a mask yoked to eye movements: experiments on letters, words and biological movement with prolonged hemifield stimulation.

We describe the first use of a new technique, which permits prolonged presentation to one or other visual field of complex, realistic, "ecologically valid" stimuli. An infrared eye movement transducer is linked to a visual display such that an electronic mask (of adjustable dimensions) or, alternatively, a "window" can be made to move as consequence of eye movements. The mask can be made to move exactly with the initiating eye movement, or with positive gain, or in the opposite direction (with or without gain), or in both directions simultaneously ("scissoring"). Alternatively, the apparatus can be set to blank the entire display should an eye movement occur with an excursion greater than a preset criterion level. The display itself can be either computer generated or can consist of a pre-recorded video film. We report preliminary findings with this apparatus. When subjects detected a letter target in a three-by-three letter matrix of laterally presented letters, exposure durations from 50 msec to 400 msec showed consistent right visual field (RVF) superiorities. (Nor was there any evidence of left visual-field, LVF, superiorities at very brief exposures as others have claimed.) Equally strong RVF superiorities also appeared when subjects decided whether or not two simultaneously and laterally presented (for 500 msec) words rhymed, the word pairs being phonologically and orthographically similar (DOWN-GOWN), phonologically similar and orthographically distinct (FARE-HAIR), phonologically distinct and orthographically similar (MOWN-DOWN), or both phonologically and orthographically distinct (FORT-GOAT). Finally, Johansson's (1973, 1976) biological movement procedure was adapted for lateral viewing, with unlimited exposure times. However, the predicted LVF superiority did not eventuate, when subjects decided whether moving points of light, attached to the limbs of darkened walkers, were worn by males or females. Further possible applications of this technique are described for normal and clinical subjects.

Eye Movements↗

PubMed1993

A panning DLT procedure for three-dimensional videography.

The direct linear transformation (DLT) method [Abdel-Aziz and Karara, APS Symposium on Photogrammetry. American Society of Photogrammetry, Falls Church, VA (1971)] is widely used in biomechanics to obtain three-dimensional space coordinates from film and video records. This method has some major shortcomings when used to analyze events which take place over large areas. To overcome these shortcomings, a three-dimensional data collection method based on the DLT method, and making use of panning cameras, was developed. Several small single control volumes were combined to construct a large total control volume. For each single control volume, a regression equation (calibration equation) is developed to express each of the 11 DLT parameters as a function of camera orientation, so that the DLT parameters can then be estimated from arbitrary camera orientations. Once the DLT parameters are known for at least two cameras, and the associated two-dimensional film or video coordinates of the event are obtained, the desired three-dimensional space coordinates can be computed. In a laboratory test, five single control volumes (in a total control volume of 24.40 x 2.44 x 2.44 m3) were used to test the effect of the position of the single control volume on the accuracy of the computed three dimensional space coordinates. Linear and quadratic calibration equations were used to test the effect of the order of the equation on the accuracy of the computed three dimensional space coordinates. For four of the five single control volumes tested, the mean resultant errors associated with the use of the linear calibration equation were significantly larger than those associated with the use of the quadratic calibration equation. The position of the single control volume had no significant effect on the mean resultant errors in computed three dimensional coordinates when the quadratic calibration equation was used. Under the same data collection conditions, the mean resultant errors in the computed three dimensional coordinates associated with the panning and stationary DLT methods were 17 and 22 mm, respectively. The major advantages of the panning DLT method lie in the large image sizes obtained and in the ease with which the data can be collected. The method also has potential for use in a wide variety of contexts. The major shortcoming of the method is the large amount of digitizing necessary to calibrate the total control volume. Adaptations of the method to reduce the amount of digitizing required are being explored.

Biomechanical Phenomena↗

PubMed1994

Observations on the anatomy and pathology of the palmar intercarpal ligaments in the middle carpal joints of thoroughbred racehorses.

Ten carpi from juvenile Thoroughbred horses were dissected in detail to record the anatomy of the palmar intercarpal ligaments (PICLs). These were found not to be substantially attached to the palmar carpal ligament. The lateral PICL was sited at the convergence of the palmar aspects of the third, fourth, intermediate and ulnar carpal bones and aligned predominantly in a proximodistal direction. The medial PICL had a large origin distally on the lateral aspect of the radial carpal bone (Cr) and attached to third (C3) and second (C2) carpal bones with apparently separate fibre orientations. Fibres between Cr and C3 aligned obliquely from dorsoproximomedial to palmarodistolateral which corresponds to the direction of movement of Cr relative to C3 during carpal extension. Video recordings of arthroscopic evaluations of 67 middle carpal joints of juvenile Thoroughbred horses in race training were reviewed retrospectively and the osteochondral and ligamentous pathology visible in each recorded. Damage to the Cr-C3 part of the medial PICL was present in 47 (70%) joints and, in 6 joints, comprised complete rupture of this branch. A significant (P < 0.001) relationship was found between the presence of remodelling of the dorsodistal margin of Cr and the severity of ligament damage. It is considered that the orientation of fibres of the Cr-C3 branch of the MPICL is consistent with a putative role to alternate forces borne by Cr and C3 during axial loading of the limb and that the injuries of this structure seen in young racehorses may represent a fatigue-type pathology analogous to that seen concurrently in the related osteochondral tissues.

Animals↗

PubMed2004

The activity of abdominal stretch receptors during non-giant swimming in the crayfish Cherax destructor and their role in hydrodynamic efficiency.

Recordings were made from the nerve innervating the stretch receptors of the abdominal muscle receptor organs and slow extensor muscles of tethered crayfish, Cherax destructor, during so-called "non-giant swimming". The stretch receptors were active during the flexor phase of swimming but the duration and pattern of activity varied from cycle to cycle. Their pattern of firing was modified by the activity of the large accessory neurons which make direct inhibitory synapses upon them. Neither the stretch receptors nor the accessory neurons were active during the extensor phase of the cycle. The timing and extent of tailfan movements during the period of stretch receptor activity were measured from video records before and after the stretch receptor nerves were cut in the second to fifth segments. The promotion of the tailfan during flexion was significantly delayed and the minimum angle to which the uropods were remoted at the end of flexion significantly larger in denervated animals. We propose that afferent information from the stretch receptors coordinates the timing and extent of tailfan movements according to variations in the positioning and movement of the abdominal segments such that the hydrodynamic efficiency of the tailfan is enhanced on a cycle by cycle basis during non-giant swimming.

Abdominal Muscles↗

PubMed1999

The influence of different exercise regimens on the development of locomotion in the foal.

To study the influence of different exercise regimens on the development of locomotion, 40 Warmblood foals aged 1 week were subdivided into 3 groups: box-rest, training and pasture exercise. The box-rest group remained for 24 h a day in a box stall while the training group was housed similarly, but additionally received a 30 min workout with gallop sprints 6 times a week. The pasture group served as a control group and was kept at pasture for 24 h a day. After 5 months, the locomotion pattern at the trot of every foal was recorded overground with a 2-D MacReflex gait analysis system. A randomly selected group of 19 foals was recorded again at age 11 months after they had been kept in an open loose box with access to a small paddock without any specific training for 6 months duration. At 5 months of age the box-rest group moved with a more protracted forelimb, and more extended shoulder and elbow joints than the pasture group. Carpal and fetlock joint kinematics were rather similar in all groups. In the hindlimb, the box-rest foals were significantly different from the other 2 groups, reflected in a more retracted hindlimb, more hip extension, more flexed stifle and tarsal joints, and a larger maximal flexion of hip, stifle, tarsal and fetlock joints. In the simultaneous video recordings this locomotion pattern was visible as a hypermetric movement. The larger protraction in the forelimb and retraction in the hindlimb, as seen in the box-rest group, is opposite to the interlimb coordination of a superior moving horse. The pastured foals had a smaller range of motion of the shoulder and hip joint and less maximal step height of both fore and hind hooves, while the velocity and step length were similar between the 3 groups. Pastured foals could trot the same distance with less joint motion and therefore had a more efficient intralimb coordination. The training group moved in a way comparable with the box-rest group in the similar velocity box-rest foals trot with an abnormal, hypermetric and therefore inefficient and poorer locomotion pattern. When, superimposed on box-rest, exercise is provided in the form of gallop sprints, this will mainly improve the hindlimb locomotion. These induced differences in locomotion pattern of foals can be reversed when the foals afterwards are subjected to the same exercise regimen again.

Animals↗

PubMed1990

Impressions of parkinsonian patients from their recorded voices.

The voices of patients suffering from Parkinson's disease change in various ways. This paper sets out to examine the effect of these changes on the impressions made on listeners, and to try to see what vocalic and prosodic features account for these impressions. Tape recordings from segments of interviews with 4 patients, and 4 control subjects with ischaemic heart disease, were played to 16 naive listeners. These listeners were asked to rate their impressions of these voices on 15 dimensions of personality. There were significant differences on most of the dimensions, despite the fact that there were no differences between the two groups on such scales as Beck's depression inventory and the mood adjective check list. The parkinsonian patients were seen to be cold, withdrawn and anxious, not to relate well to the interviewer and to be enjoying the interview less than the controls. These ratings are very similar to those previously reported for the same patients, using silent video recordings only. The voice recordings were analysed along various dimensions of prosody. The factors which were different between the groups included the frequency and type of pauses in speech and the range or variability of the fundamental frequency. The implications of this exploratory study for intervention are discussed.

Humans↗

PubMed1994

An improved microscope stage for direct observation of freezing and freeze drying.

A microscope stage for observation of freezing and freeze drying is described. The stage uses thermoelectric (Peltier) heaters configured in two stages, with circulating fluid as a heat sink on the high temperature side. Lowest attainable sample temperature is about -47 degrees C. Principal advantages of this system are closed-loop control of stage temperature, rapid response to changes in temperature set point, and improved documentation of experiments by use of a video recorder system with a character generator which allows display of sample identity and temperature. Accuracy of measuring the sample temperature in the field of view was validated by comparing observed values of eutectic melting with published values for a series of solutes with eutectic temperatures in the range from -2 degrees C to -32 degrees C. Good agreement was obtained throughout this range.

Freeze Drying↗

PubMed2002

Central and peripheral temperature change in normal infants.

The purpose was to explore the relationship between the fall in rectal temperature seen in normal infants after being put down to sleep and the concomitant rise in peripheral shin temperature. In this observational study 21 normal infants had continuous overnight peripheral shin and central rectal temperature recorded, for three nights at 2 weeks, 6 weeks, 3 months and 5 months of age. Parents documented the start and end of feed/nappy changing episodes during the night. All recordings were made in the infants' own home. A strong inverse linear correlation (median r2 = 0.95, lower quartile 0.92, upper quartile 0.97) was seen between rectal temperature and shin temperature on falling to sleep when put down on 106 (65%) of 161 nights. On many other nights a significant nonlinear association was present. It was not possible to exclude the process of being put down to sleep as a confounding variable in this strong association. However, a similar inverse relationship between shin and rectal temperature was seen overnight during 111 of 121 (92%) feed/nappy changing episodes. If causal, the development in early infancy of an inverse relationship between shin and rectal temperature may be important for cardiovascular homeostasis. Further sleep laboratory work including video recording is required to separate the peripheral and central temperature changes that take place on falling to sleep from those associated with removal of clothing during a nappy change.

Ankle↗

PubMed1997

Feeding kinematics of juvenile swellsharks, Cephaloscyllium ventriosum

To investigate how feeding behaviors change with prey size, high-speed video recording was used to examine the kinematics of prey capture and transport in 1-year-old swellsharks Cephaloscyllium ventriosum (Scyliorhinidae: Carchariniformes) feeding on two differently sized prey items. Prey capture in these sharks generally consisted of an initially ram-dominated capture bite, one or more manipulation bites, a holding phase during which the food was held in the teeth of the shark, and then suction-dominated prey transport. During initial capture and transport, most of the water taken in is forced back out of the mouth anteriorly rather than continuing posteriorly out through the gill openings. Dye experiments in which dye-perfused prey items were ingested by the sharks confirm this observation; distinct jets of colored water were video-taped as they were ejected from the mouth. Very late in prey transport, a bolus of water is ejected through the gill slits; however, by this time, the majority of water appears already to have exited the buccal cavity through the mouth. Such patterns were observed for sharks feeding on both small and large prey items. Although a basic pattern of prey capture and transport was regularly repeated among strikes, kinematic patterns during prey capture and transport were variable both within and among individuals, indicating that prey acquisition is not tightly controlled. However, the amount of variability was similar among prey sizes. In addition, there were no detectable changes in behavior due to prey item size. Ram-suction index values confirmed that similar capture modes were being utilized for both prey sizes.

Journal Article↗

PubMed1993

Efficacy of felbamate in childhood epileptic encephalopathy (Lennox-Gastaut syndrome).

BACKGROUND: The Lennox-Gastaut syndrome is a childhood disorder characterized by multiple types of seizures, mental retardation, characteristic electroencephalographic abnormalities, and resistance to standard antiepileptic drugs. Felbamate is an investigational antiepileptic drug with a preclinical profile that suggests it would be effective in patients with multiple types of seizures. In controlled clinical trials, felbamate was superior to placebo in reducing the frequency of refractory partial-onset seizures. METHODS: We studied the efficacy of felbamate in 73 patients ranging in age from 4 to 36 years who had the Lennox-Gastaut syndrome. During a 28-day base-line phase, the patients received their usual antiepileptic therapies. At the end of this phase, felbamate or placebo was administered for 70 days in addition to the current antiepileptic medications. The dosage of felbamate was titrated during the first 14 days of the treatment phase to a maximum of 45 mg per kilogram of body weight per day or 3600 mg per day, whichever was less. The primary efficacy variables were the total number of seizures counted during a four-hour period of video recording, parents' or guardians' global evaluations of the patients' quality of life, and the total number of atonic seizures, as reported by parents or guardians. RESULTS: The patients treated with felbamate had a 34 percent decrease in the frequency of atonic seizures, as compared with a 9 percent decrease in the patients who received placebo (P = 0.01). The felbamate-treated patients had a 19 percent decrease in the total frequency of seizures, as compared with a 4 percent increase in the placebo group (P = 0.002). The global-evaluation scores were significantly higher in the felbamate group than in the placebo group from day 49 to the end of the study. There were no significant differences in the frequency of seizures occurring during video monitoring, but there was a significant reduction (P = 0.017) in the number of tonic-clonic seizures during the maintenance period in the felbamate group. The types and frequency of side effects were similar in the two treatment groups. CONCLUSIONS: Felbamate is beneficial in patients with the Lennox-Gastaut syndrome.

Adolescent↗

PubMed1996

Tensile behaviour of fibroblasts cultured in collagen gel.

An in vitro morphological study on the relation of the stress field and the orientation of cells with the use of the time lapse video recording system was carried out. Specimens of thin collagen gel membrane, within which cells are proliferating, were examined under various mechanical conditions. Cell stretching, cell orientation, cell migration, cell proliferation and generation of tensile stress in collagen gel were recorded. It was demonstrated that fibroblasts generate tension and change their orientation along the tensile direction. A hypothetical mechanism for such phenomena is proposed, that is, fibroblasts generate tension and make tense collagen fibres, then cells stretch themselves along the tense fibres and increase tension in this direction. Thus, this mechanism works as a positive feedback loop which enables cells to make tensile stresses and align along them in accordance with the mechanical environment.

Animals↗

PubMed1998

[Decentralized special training in pulmonary medicine. A project using telemedicine].

In arctic Norway, where there is a lack of specialists in pulmonary medicine two postgraduate students, already qualified as specialists in internal medicine at Tromsø Regional Hospital, applied to continue their training at their respective local hospitals. The regional hospital in Tromsø has a long tradition of telemedicine, with network links to local hospitals in the region, and is equipped for interactive consultation and the bilateral transmission of x-rays and video recordings, and digital transmission of x-rays. Accordingly, supported by their supervisor, the two postgraduate students applied to the committee for postgraduate education in pulmonary medicine to have a year's work at their respective local hospitals, supervised via the telemedicine facilities, accepted as equivalent to a six-month module of the normal syllabus. The project was approved and executed as planned. The registrars, who were responsible for pulmonary service at their local hospitals, served four days a month at the regional hospital, and their supervisor visited the local hospitals one day each month. All internal education at the regional hospital was made available by means of a weekly interactive televised link-up, x-rays being displayed on screen as transmitted digitally; bronchoscopies were shown by video, and ad hoc tutorials arranged as needed. Evaluated by the national committee, the project was found satisfactory, and the registrars were duly qualified.

Arctic Regions↗

PubMed1999

Assessment of general practitioners by video observation of communicative and medical performance in daily practice: issues of validity, reliability and feasibility.

OBJECTIVES: To develop a video assessment method for General Practitioners (GPs) by analysing issues of validity, reliability and feasibility of observation of videotaped regular consultations. DESIGN: In a cross-sectional study consultations of 93 GPs were video recorded in the practice during 1 week. The GPs registered consultation and patient data in a logbook; 16 consultations per GP were selected using preset criteria. The quality of communicative and medical performance of these consultations was assessed by GP observers with a validated instrument. The validity of the procedure was evaluated by checking the content of each GP's sample using specific sample criteria. Selection bias was estimated by multiple regression analysis, with sample characteristics as independent variables and scores on communication and medical performance as dependent variables. The influence of observation on GPs and patients was assessed by a questionnaire. Generalizability theory was used to estimate reliability. Feasibility was assessed by conducting a questionnaire, by keeping accounts, and by checking the technical quality of the videotaped consultations. SETTING: Universities of Nijmegen and Maastricht, The Netherlands. SUBJECTS: General Practitioners (GPs). RESULTS: The domain of general practice was well covered in the samples; content validity was satisfactory. With regard to the sample characteristics, only the total duration of consultations appeared to correlate significantly with both the score on communication and the score on medical performance. A majority (71%) of GPs reported not being influenced by the observation, except in the first cases, and recognizing their usual daily performance in the videotaped consultations. An acceptable level of reliability was reached after 2.5 hours of observation, i.e. 12 cases by a single observer. The method was well accepted by both GPs and patients. The costs were pound250 per GP. CONCLUSIONS: Video assessment of GPs in daily practice according to the procedures described is a valid and reliable method, one which is useful for education and quality improvement. There is a trade-off between feasibility on one hand and validity, reliability and credibility on the other hand. Compared to investments in observation methods in standardized settings, the costs of video observation of GPs' actual performance are acceptable.

Clinical Competence↗

PubMed1997

Chemotaxis of Amoeba proteus in the developing pH gradient within a pocket-like chamber studied with the computer assisted method.

A new "U" shaped, pocket-like chamber was used to observe the chemotactic responses of individual cells. This method permits monitoring of both the development of the concentration gradient of a tested substance and cell locomotion. We investigated the chemotactic responses of Amoeba proteus and observed that the amoebae moved in positively and negatively developing [H+] gradients towards the solution of lower pH in a pH range 5.75-7.75. The chemotactic response of amoebae to [H+] gradients required the presence of extracellular calcium ions. It was blocked and random locomotion was restored by the replacement of calcium with magnesium in the cell medium. Time-lapse video recording and data processing were accomplished with computer-assisted methods. This made it possible to compare selected methods of data presentation and analysis for cells locomoting in isotropic and anisotropic conditions. The cell trajectories were determined and displayed in circular diagrams, lengths of cell tracks and final cell displacements were estimated and a few parameters characterizing cell locomotion were computed.

Amoeba↗

PubMed2006

Transparent polymeric cell culture chip with integrated temperature control and uniform media perfusion.

Modern microfabrication and microfluidic technologies offer new opportunities in the design and fabrication of miniaturized cell culture systems for online monitoring of living cells. We used laser micromachining and thermal bonding to fabricate an optically transparent, low-cost polymeric chip for long-term online cell culture observation under controlled conditions. The chip incorporated a microfluidic flow equalization system, assuring uniform perfusion of the cell culture media throughout the cell culture chamber. The integrated indium-tin-oxide heater and miniature temperature probe linked to an electronic feedback system created steady and spatially uniform thermal conditions with minimal interference to the optical transparency of the chip. The fluidic and thermal performance of the chip was verified by finite element modeling and by operation tests under fluctuating ambient temperature conditions. HeLa cells were cultured for up to 2 weeks within the cell culture chip and monitored using a time-lapse video recording microscopy setup. Cell attachment and spreading was observed during the first 10-20 h (lag phase). After approximately 20 h, cell growth gained exponential character with an estimated doubling time of about 32 h, which is identical to the observed doubling time of cells grown in standard cell culture flasks in a CO2 incubator.

Cell Culture Techniques↗

PubMed2006

A novel approach to the study of human microcirculation: Reactivity to locally applied angiotensin II in the conjunctival microvascular bed.

OBJECTIVE: To develop a state-of-the-art, computer-assisted intravital microscopy protocol to evaluate directly the effects of topically applied drugs on conjunctival arteriolar and venular diameters. METHODS: Fifty-one normotensive volunteers were studied. Video-recordings of the bulbar conjunctival microcirculation were made before and following eye drops containing angiotensin II (AngII) (0.001% w/w, or 0.01%) or phenylephrine (0.25%). The computer-assisted analyses of arteriolar and venular diameters were performed off-line. In different protocols the microvascular reactivity to the different eye drops were compared. RESULTS: AngII (0.01%) eye drops, but not AngII (0.001%), induced significant constriction in both arterioles (median, 19%) and venules (13%). Phenylephrine eye drops (pharmacological control) induced similar arteriolar (18%) and venular (12%) constrictions. Repeated AngII challenges with a 30-min interval revealed reproducible vasoconstriction responses (median arteriolar constriction, 11 and 17%, respectively; NS). The vasoconstriction responses following AngII challenges on two consecutive days revealed reproducible responses (median arteriolar constriction, 13 and 11%, respectively; NS). CONCLUSIONS: The present results demonstrate that the proposed model for noninvasive intravital video-microscopy of the conjunctival microcirculation is sensitive for measuring direct arteriolar and venular reactivity following topically applied drugs. We consider this model a valuable tool for sophisticated research on in-vivo microvascular reactivity in humans.

Administration, Topical↗

PubMed1998

Quantification of physical activities by means of ambulatory accelerometry: a validation study.

The objective of the study was to assess the validity of an activity monitor (AM) within a psychophysiological study. The AM was based on four body-fixed accelerometers and discriminated postures, transitions, and dynamic activities. Three subjects participated in each of two 4-hr sessions. During each session, consisting of two protocols, ambulatory accelerometer and heart rate measurements were made. The output of the AM was compared with simultaneously recorded video tapes. An overall agreement between AM and video of 88 and 96% was found. The number of transitions and dynamic periods, and the duration of activities were well determined. Posture-related heart rate changes were demonstrated. A three-sensor configuration hardly influenced the validity scores. The AM appeared to be a valid instrument to quantify aspects of physical activity, and offers new possibilities for ambulatory psychophysiological research.

Adult↗

PubMed1998

Rapid actin-based plasticity in dendritic spines.

Dendritic spines have been proposed as primary sites of synaptic plasticity in the brain. Consistent with this hypothesis, spines contain high concentrations of actin, suggesting that they might be motile. To investigate this possibility, we made video recordings from hippocampal neurons expressing actin tagged with green fluorescent protein (GFP-actin). This reagent incorporates into actin-containing structures and allows the visualization of actin dynamics in living neurons. In mature neurons, recordings of GFP fluorescence revealed large actin-dependent changes in dendritic spine shape, similar to those inferred from previous studies using fixed tissues. Visible changes occurred within seconds, suggesting that anatomical plasticity at synapses can be extremely rapid. As well as providing a molecular basis for structural plasticity, the presence of motile actin in dendritic spines implicates the postsynaptic element as a primary site of this phenomenon.

Actins↗