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At least 919 records · Page 51Linked to original sources

PubMed1992

Co-ordination of pumping in isolated bovine lymphatic vessels.

1. Segments of bovine mesenteric lymphatic of varying diameter taken from different parts of the lymphatic tree were cut to 20 mm in length and set up so that measurements could be made of spontaneous isometric contractions. 2. There was considerable variability in frequency of spontaneous contractions but this was independent of resting tension. There was no significant correlation between lymphatic diameter and inherent frequency of contraction. 3. Isolated segments of bovine mesenteric lymphatic 70-80 mm in length were cannulated and set up in a three-compartment organ bath which allowed independent temperature control in each compartment. Pressure was recorded at inflow and outflow ends and experiments were video recorded. 4. Contractile activity was normally initiated at the end of the lymphatic maintained at the higher temperature and the contractile wave was propagated along the length of the vessel. 5. Propagation could occur either in the direction of valve orientation (orthograde) or retrogradely. The volume of fluid pumped was not significantly affected by the direction of propagation. 6. Perfusion of the central compartment with Krebs solution at 0-2 degrees C disrupted normal propagation and allowed the two parts of the lymphatic to contract at different frequencies although the two parts maintained an approximately 2:1 ratio. 7. Perfusion of the central compartment with 10 mM-heptanol also disrupted normal propagation but the rates on either side of the partition bore no harmonic relationship to one another. 8. These results suggest that relatively short segments of lymph duct have the ability to contract spontaneously and that their inherent frequencies are not determined by their position in the lymphatic tree. The results are consistent with the existence of electrical coupling along the lymphatic's length and they suggest that over distances of at least 80 mm independent pacemakers are capable of mutual entrainment at a frequency representing a compromise between the fastest and slowest components.

Alcohols↗

PubMed2005

A six year prospective study of the incidence and causes of head and neck injuries in international football.

OBJECTIVE: To identify those risk factors that have the greatest impact on the incidence of head and neck injuries in international football. METHOD: A case-control study of players sustaining head and neck injuries during 20 FIFA tournaments (men and women) from 1998 to 2004. Video recordings of incidents were used to identify a range of parameters associated with the incidents. Team physicians provided medical reports describing the nature of each injury. chi2 tests (p< or =0.01) and 95% confidence intervals were used to assess differences in distribution and incidence of injury, respectively. RESULTS: In total, 248 head and neck injuries were recorded of which 163 were identified and analysed on video sequences. The commonest injuries were contusions (53%), lacerations (20%), and concussions (11%). The incidence of all head and neck injuries was 12.5/1000 player hours (men 12.8, women 11.5) and 3.7 for lost-time injuries (men 3.5, women 4.1). The commonest causes of injury involved aerial challenges (55%) and the use of the upper extremity (33%) or head (30%). The unfair use of the upper extremity was significantly more likely to cause an injury than any other player action. Only one injury (a neck muscle strain) occurred as a result of heading the ball throughout the 20 tournaments equivalent to 0.05 injuries/1000 player hours. CONCLUSIONS: Players' actions most likely to cause a head or neck injury were the use of the upper extremity or the head but in the majority of cases these challenges were deemed to be fair and within the laws of the game.

Adolescent↗

PubMed1987

Analysis of in vivo cell movement using transparent tissue systems.

The embryos of certain teleost species are transparent and cell behaviour within the intact embryo can be observed and recorded using Nomarski microscopy coupled with time-lapse video recording or time-lapse cine filming. In this report we review some of our recent analyses of cell behaviour patterns underlying key morphogenetic events. (1) Contact-guided cell migration through a structurally ordered extracellular matrix during fin development; (2) movement of tissue layers during epibolic overgrowth; and (3) cell 'social' behaviour during the establishment of the body axis (i.e. notochord formation and somitogenesis). These results, on cell behaviour correlated with normal morphogenesis, provide a baseline for further work in which hypotheses concerning subcellular and molecular controls of cell behaviour can be tested by experimental perturbation in vivo.

Animals↗

PubMed2001

Effects of stretch receptor ablation on the optomotor control of lift in the hawkmoth Manduca sexta.

In insects, fast sensory feedback from specialized mechanoreceptors is integrated with guidance cues descending from the visual system to control flight behavior. A proprioceptive sensory organ found in both locusts and moths, the wing hinge stretch receptor, has been extensively studied in locusts for its powerful influence on the activity of flight muscle motoneurons and interneurons. The stretch receptor fires a high-frequency burst of action potentials near the top of each wingstroke and encodes kinematic variables such as amplitude and timing. Here, I describe the effects of stretch receptor ablation on the visual control of lift during flight in the hawkmoth Manduca sexta. Using a combination of extracellular muscle recordings, force and position measurements and high-speed video recording, I tracked power muscle activity, net vertical flight force (lift), abdomen deflection and wing kinematics in response to image motions of varying velocity during tethered flight in a wind tunnel. As a result of bilateral ablation of the wing hinge stretch receptors, visually evoked lift decreased to nearly one-third of that exhibited by intact animals. The phase and frequency of indirect power muscle action potentials and the patterns of abdominal deflection were unaffected; however, wingstroke amplitude was clearly reduced after ablation. Collectively, these results suggest that stretch receptor feedback is integrated with descending visual cues to control wing kinematics and the resultant aerodynamic force production during flight.

Animals↗

PubMed1991

Effects of a single session of prolonged plantarflexor stretch on muscle activations during gait in spastic cerebral palsy.

Activations of the triceps surae (TS) and tibialis anterior (TA) muscles during gait were studied in children with spastic cerebral palsy (CP) immediately before and after 30 min of standing on a tilt-table with the ankle dorsiflexed to stretch the TS in the experimental group (n = 8) or after a rest period in the control group (n = 11). The EMG activity from the TS and TA was recorded concomitantly with electronic footswitch signals by a computer. Video records were made of the sagittal gait movements. Effects of PMS were determined by comparing change scores for selected spatiotemporal and muscle activation parameters between the groups. The change scores defined for the muscle activations were: a post-test/pre-test ratio of the EMG activity in specific segments of the gait cycle and a locomotor spasticity index. PMS did not significantly (p greater than 0.05) affect any of the spatiotemporal parameters nor did it alter any of the TS and most of the TA activation parameters or the SI indexes for the TS and TA. Only the TA post/pre activation ratio for the 0-16% segment of the gait cycle was smaller (p less than 0.01), indicating a decrease in TA activation post-PMS.

Adolescent↗

PubMed1981

[Diagnosis of atrial left-to-right shunts by cross-sectional contrast echocardiography (author's transl)].

We have used cross-sectional contrast echocardiography with peripheral venous injection in 3 groups of patients: A) 23 patients with atrial septal defect (ASD); B) 19 patients with various forms of heart disease, but no evidence of ASD; C) 11 patients with proven interatrial communication, but no significant left-to-right shunt. The contrast studies were performed with a mechanical sector scanner and were evaluated retrospectively but "blindly", i.e. without knowing the patient's name and diagnosis and without knowing that part of the echocardiogram, which had been recorded before injecting contrast. The sound track of the video recorder was turned off. Left-to-right atrial shunting could be demonstrated in 20/23 (87%) patients with ASD, and in all 14 patients in whom both the parasternal and the apical examination technique had been used. The left-to-right shunt was seen as a stream of contrast-free blood flowing from the left atrium into the right atrium and washing away the contrast echoes at the site of the defect. This "negative contrast" or "wash-out" effect was accompanied by turbulences in the right atrium. All 22 patients with this sign had interatrial communications, but interestingly there were 2 patients in whom no definite left-to-right shunt could be demonstrated by oxymetry. Thus the "wash-out" phenomenon seems to be specific for a defect, but not necessarily a significant left-to-right shunt. Right-to-left atrial shunts were diagnosed in 65% of the ASD group. A left-to-right or right-to-left shunt was never diagnosed in any of the control patients. Seemingly turbulent blood flow, the intermittent appearance of contrast-free blood (presumably from the coronary sinus or the inferior vena cava) in the right atrium and a "wash-out" effect at the site of the entry of the inferior vena cava are potential sources of error. However, our blind analysis has shown that these pitfalls can be avoided.

Diagnosis, Differential↗

PubMed1997

[Investigation of epilepsy. Magnetic tomography more and more important as a diagnostic technique].

Electroencephalography (EEG) and neuroradiology are both indispensible techniques in cases of suspected epileptic seizure, when the aim of investigation is to determine whether the seizure was of epileptic nature, and if so whether it was the result of specific provocative factors or an expression of epileptic disease. In the latter case, the epileptic condition should be classified and its aetiology determined, if possible. Routine or sleep EEG providing interictal epileptiform discharges is a useful aid to differential diagnosis. To obtain EEG recordings during actual seizures, long-term recordings, using either ambulatory equipment or an EEG-video procedure, are usually used. The combination of EEG and video recording, using surface or surgically implanted electrodes, is a procedure of major importance in the evaluation of patients refractory to medical treatment and possible candidates for epilepsy surgery. In cases of epilepsy suspected to be caused by tumour or cerebrovascular disease, neurological investigation does not differ from that routinely used in such conditions. MRI (magnetic resonance imaging) techniques have become important aids in the preoperative work-up in cases of chronic therapy-resistant partial epilepsy. MRI has also simplified the identification of minor morphological abnormalities causing partial epilepsy, and is the method of choice in such cases. The sensitivity of MRI is improved by its combination with volumetric measurements and spectroscopy. The use of functional neuroimaging with SPECT (single photon emission computed tomography) and PET (positron emission tomography) during seizures provides further information. A promising new development is the co-registration of MRI and functional imaging (dipolar reconstruction of EEG spikes and seizure patterns, SPECT, PET). MRI is a cornerstone of the preoperative work-up, but diagnosis and the choice of therapeutic approach is always based on the clinical picture, EEG, and functional and morphological imaging.

Animals↗

PubMed1999

Exploring the effects of tape-recording on personality assessment.

This study examined the possible influence of audio and video recording of personality assessment measures on anxiety. Undergraduate students in psychology were randomly assigned to Audiotape, Videotape, or Control conditions and given the State-Trait Anxiety Inventory and Rorschach Inkblot Method. A one-way multivariate analysis of variance indicated no significant differences among these conditions on the Spielberger, et al. State-Trait Anxiety Inventory, A-State scale, and five Rorschach measures of situational anxiety. Tape-recording itself did not seem to affect the anxiety indices of these frequently used personality assessments.

Adult↗

PubMed2006

Detection of cardiac cycle from intracoronary ultrasound.

In this paper, we describe a method automatically to determine the phase of a cardiac cycle for each video frame of an intravascular ultrasound (IVUS) video recorded in vivo. We first review the principle of IVUS video and demonstrate the general applicability of our method. We show that the pulsating heart leads to phasic changes in image content of an IVUS video. With an image processing method, we can reverse this process and reliably extract the heart-beat phase directly from IVUS video. With the phase information, we demonstrate that we can build 3-D (3D) time-variant shapes and measure lumen volume changes within a cardiac cycle. We may also measure the changes of IVUS imaging probe off-center vector within a cardiac cycle, which serves as an indicator of vessel center-line curvature. The cardiac cycle extraction algorithm requires one scan of the IVUS video frames and takes O(n) time to complete, n being the total number of the video frames. The advantage of this method is that it requires no user interaction and no hardware set-up and can be applied to coronary scans of live beating hearts. The extracted heart-beat rate, compared with clinical recordings, has less than 1% error.

Animals↗

PubMed1998

Effect of tape recording on perturbation measures.

Tape recorders have been shown to affect measures of voice perturbation. Few studies, however, have been conducted to quantitatively justify the use or exclusion of certain types of recorders in voice perturbation studies. This study used sinusoidal and triangular waves and synthesized vowels to compare perturbation measures extracted from directly digitized signals with those recorded and played back through various tape recorders, including 3 models of digital audio tape recorders, 2 models of analog audio cassette tape recorders, and 2 models of video tape recorders. Signal contamination for frequency perturbation values was found to be consistently minimal with digital recorders (percent jitter = 0.01%-0.02%), mildly increased with video recorders (0.05%-0.10%), moderately increased with a high-quality analog audio cassette tape recorder (0.15%), and most prominent with a low-quality analog audio cassette tape recorder (0.24%). Recorder effect on amplitude perturbation measures was lowest in digital recorders (percent shimmer = 0.09%-0.20%), mildly to moderately increased in video recorders and a high-quality analog audio cassette tape recorder (0.25%-0.45%), and most prominent in a low-quality analog audio cassette tape recorder (0.98%). The effect of cassette tape material, length of spooled tape, and duration of analysis were also tested and are discussed.

Humans↗

PubMed1987

The assessment of pain in rheumatoid arthritis. Validity of a behavioral observation method.

It is difficult to objectively measure pain in rheumatoid arthritis (RA). A behavioral observation method for the assessment of RA pain has been developed. In this study, videotapes were made of 53 RA patients while they performed standardized maneuvers. Trained raters viewed the videotapes and recorded the frequencies of 7 pain behaviors. Clinical and laboratory measures of rheumatoid disease activity also were recorded for each patient. Rheumatology fellows viewed 20 randomly chosen video recordings of the patients and made global estimates of the intensity and unpleasantness of pain. Significant positive correlations were found between total pain behavior scores and measures of disease activity. The fellows' estimates of the intensity and unpleasantness of the patients' pain also were significantly and positively correlated with the total pain behavior scores. The behavioral observation method may be useful in the assessment of RA pain and may be included as an objective outcome measure in clinical trials with RA patients.

Adult↗

PubMed2000

The effect of group housing on feeding patterns and social behaviour of previously individually housed growing pigs.

Group housed pigs make less frequent feeder visits of longer duration, and eat at a faster rate than pigs housed individually. They also have lower growth rates which may be due to elevated stress levels resulting from changes in the concentrations of hormones, such as cortisol and adrenaline associated with aggression and social stress. The aim of this experiment was to investigate the effects of grouping on feeding pattern, time budgeting and the social behaviour of pigs kept as individuals from weaning until grouping. In total, 12 Large WhitexLandrace male pigs (four pigs per block) mean (+/-S.E.) start weight 22.5+/-0.7kg were housed individually for 3 weeks (Period 1) after which in two replicates (Blocks 1 and 3), pigs were combined into a group of four (Period 2) before being returned to individual housing for a further 3 weeks (Period 3). In Block 2, the four pigs remained as individuals across periods but were moved between pens at the end of Periods 1 and 2 to account for any pen effects. Feeding pattern and food intake were recorded throughout and pigs were weighed three times a week. Video recordings and live behavioural observations were made to record time budgets and social behaviour. Grouped pigs made less visits to the feeder in Period 2 than when they were housed individually in Periods 1 (P<0.001) and 3 (P<0.01). Visit duration was longer in Period 2 than in Periods 1 (P<0.01) and 3 (P<0.05). Food intake and weight gain were greater in Period 3 than in Periods 1 and 2 (P<0.001 and P<0.01, respectively). There were no significant effects of moving pigs between pens in Block 2 on feeding behaviour and timebudgets. In Period 2, grouped pigs slept more (P<0.01) and spent less time feeding (P<0.01) and rooting (P<0.01) than in Periods 1 and 3. The frequency of aggression decreased over time from mixing (P<0.001). Possible explanations for the changes in feeding behaviour when pigs are moved from individual to group housing are competition, group cohesion, or that the high frequency of feeder visits when the pigs are housed individually is a consequence of a lack of social stimulation. Of these different possibilities, the results suggest that group cohesion is most likely to have been causal in the observed changes in feeding behaviour.

Journal Article↗

PubMed2000

The Schedule for the Assessment of Drug-Induced Movement Disorders (SADIMoD): test-retest reliability and concurrent validity.

The SADIMoD is a newly developed instrument, consisting of a compilation of rating scales, to measure the severity of drug-induced movement disorders: dystonia, dyskinesia, Parkinsonism, akathisia, ataxia, and several types of tremors. The test-retest reliability of this scale and the concurrent validity with the Abnormal Involuntary Movement Scale (AIMS), the Simpson-Angus Scale (SEE) and the Barnes Akathisia Scale (BAS) was assessed in 31 patients [20 male/11 female; 57.1+/-16.5 yr (mean+/-S.D.)] with a variety of movement disorders by six teams of investigators. The teams were trained by means of a standard package of instruction material to such an extent that a single member of the team could represent the entire team. Each patient was rated according to the AIMS, SEE and BAS and recorded on videotape according to the SADIMoD Schedule. These video-recordings were scored twice; first, in consensus by the entire team and secondly [110.3+/-58.0 d (mean+/-S.D.) later] by a single representative of that team. One team underwent a major change between scoring and was excluded from this analysis. Despite these difficult circumstances, these first and second ratings correlated to a highly significant degree with Spearman's correlation coefficients of 0.57 to 0.88 (median 0.69). The homogeneity of the applied scales was good (Cronbach's a = 0.75-0.94). Convergent validity was found between the SADIMoD dyskinesia and (to a lesser extent) dystonia scales and the AIMS as well as between the akathisia sub-scales and the BAS, with divergent validity with the other sub-scales. The SEE discriminated less well between the Parkinsonism sub-scale and the other sub-scales.

Journal Article↗

PubMed2005

The temporopolar cortex plays a pivotal role in temporal lobe seizures.

We investigated the role of the temporal pole (TP) in 48 consecutive patients with drug-refractory temporal lobe epilepsy (TLE). Chronic depth recordings of TP cortex activity were used in association with video recording of ictal symptoms during 48 spontaneous seizures. In 23 cases (48%, group 1) the TP was involved at the onset of the seizure, before or concurrently with the hippocampus. In the remaining 25 patients (52%, group 2) the TP was involved 16.4 +/- 13.8 s after the hippocampus. A past history of febrile seizures was found in both groups, with no statistical difference. Ictal symptoms did not differentiate TP seizures from seizures originating in the hippocampus but the first clinical sign occurred sooner in group 1 compared with group 2 (respectively 10.56 +/- 9 and 25.7 +/- 19 s, respectively, P = 0.005). Loss of awareness also occurred sooner in the case of TP seizures compared with mesiotemporal lobe (MTL) seizures (22.9 +/- 22.6 versus 42.2 +/- 18.6 s, P = 0.0002). MRI data analysis showed that hippocampal sclerosis was present in both groups of patients, although it was more frequent in patients with MTL onset. Anterior temporal white matter changes were found ipsilateral to the epileptogenic area and tended to be more frequent in patients with TP seizures. All the patients underwent tailored anterior temporal lobectomy that included the TP, the hippocampus, the parahippocampal gyrus and the anterior part of the lateral temporal cortex. A better postoperative outcome was achieved in group 1 compared with group 2 (Engel class 1, 95 and 72% respectively, P = 0.04). We conclude that the frequent TP involvement at the onset of seizures could be a supplementary explanation for some failures of selective amygdalohippocampectomy, which should be addressed preferentially to well-selected patients. Moreover, the involvement of the TP cortex at the onset of the seizures is a good predicting factor for postoperative seizure outcome.

Adolescent↗

PubMed1993

Analysis of the work rates and heart rates of association football referees.

This study aimed to describe the work-rate profiles of referees during soccer matches and record heart-rate responses during these games. Using video-recordings 14 referees were observed and their heart rates during the games were monitored by short-range radio telemetry. These included 11 football league matches. The exercise intensity was largely submaximal with a change in activity every 6 s. The mean distance covered during the game was 9.44 km; a significant fall in work rate was noted in the second half (P < 0.05). The mean heart rate of 165 beats min-1 did not vary between first and second halves. The work rate and heart rate varied more between individuals than with the importance of the match, but this variation was small. It was considered that refereeing top level soccer places high physiological demands on the official. This has implications for training and fitness assessment.

Adult↗

PubMed2003

[Simultaneous digital ICG and fluorescein videoangiography with the personal computer].

BACKGROUND: Since the invention of the simultaneous ICG and fluorescein (SIF) videoangiography in 1995 none of the available SLOs were significantly improved. Digital video recording with a PC can simplify and improve the quality of the angiography. METHOD: SIF angiography images of a two-wavelength scanning laser ophthalmoscope were digitized with a personal computer and written to disk with at rate of 25 images/s as a non-compressed digital video file. The digitized image sequence could be replayed with any standard video player and converted to different image and video file formats with a file conversion utility, developed specifically for the needs of SIF angiography. RESULTS: Recording of digital SIF videoangiograms with a personal computer is not more complicated than the conventional video method. Since most of the parameters of the recording software are customizable, processing methods can be tailored to individual needs. Off-line processing and/or storage of the images in a digital database are possible immediately after recording. To facilitate localization of the pathological landmarks on the fundus the two channels of the SIF angiograms can be observed as combined red-green images. CONCLUSIONS: Compared to conventional videoangiography, digital SIF videoangiography has only advantages: the image quality is better, it is less complicated and not more expensive than the conventional one. Digital recording should replace the conventional one.

Cost-Benefit Analysis↗

PubMed2000

Video rate confocal microscopic imaging of dentin/adhesive interfacial failure under load.

PURPOSE: To obtain information on interfacial failure by recording video rate images of the interface as it failed, while simultaneously recording the load applied. MATERIALS AND METHODS: Fluorescent labeled adhesives were used to retain resin-based composite bobbins on the flat exposed dentin surface of teeth included in epoxy resin blocks. The teeth were secured in a miniature straining stage while the bobbins were loaded in shear mode and the interface viewed with a tandem scanning confocal microscope. Images of the interface during failure were recorded with the aid of computer image processing and storage. The dynamic failure pattern, site of failure (after repositioning the fractured bobbin under the microscope) and shear bond stress were analyzed for four dentin adhesives [OptiBond (OB), Scotchbond Multi-Purpose Plus (SBMP+), Clearfil Liner Bond 2 (CFLB2) and ESPE Bonding System (EBS)]. Control specimens without fluorescent dyes were also studied. Four dynamic patterns of failure were observed: snap, slip/stick, peel and shock wave were seen respectively with OB, SBMP+, CFLB2 and EBS adhesive. The shear bond strengths were ranked EBS*>OB>SBMP+>CFLB2* (*statistically different at alpha=0.05). No significant difference was found between specimens with and without fluorescent dye.

Acid Etching, Dental↗

PubMed1984

Comparison between videotape and personal teaching as methods of communicating clinical skills to medical students.

The efficacy of video recording in transmitting clinical knowledge and skills to medical students was tested by recording on videotape demonstrations of physical examinations given by five clinicians to a randomly selected group of 12 students (personal group) from the first clinical year and then showing these recordings, under identical conditions, to 13 students from the same year (video group). The efficacy of both the personal and video mediums in terms of whether content was retained was tested by a questionnaire completed by all students at the end of the sessions and by a structured clinical assessment in which students were asked to demonstrate some of the same clinical tasks three weeks after the demonstration. In answering the questionnaire the video group obtained a mean (SD) score of 20.8 (7.0) (maximum possible score 40), which was not significantly different from the score achieved by the personal group (17.4 (7.7)). The video group was able to reproduce 44 (10)% of the total clinical steps demonstrated and the personal group 45 (14)%. Videotaped demonstrations can be as effective as personal teaching of clinical methods, and video should be developed as a medium for first line clinical teaching.

Clinical Competence↗