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PubMed2005

Prevention of motion sickness with rizatriptan: a double-blind, placebo-controlled pilot study.

BACKGROUND: Serotonergic triptan medications effectively reverse pain and associated symptoms of migraine. Vestibular symptoms, including dizziness and vertigo, occur in about one-third of migraineurs. The most frequent and consistent balance symptom in migraineurs is motion sickness, which is experienced by about half of migraineurs and may be related to serotonergic influences. This double-blind, placebo-controlled, crossover pilot study was designed to test the hypothesis that pre-treatment with the serotonin agonist rizatriptan would prevent motion sickness provocation in headache-free migraineurs. MATERIAL/METHODS: Ten healthy adult migraineurs (5 migrainous vertigo and 5 migraine without associated vestibular symptoms) with a history of motion sickness were tested in three sessions: a baseline vestibular battery and two motion sickness provocation sessions two hours following randomly ordered blinded pre-treatment with either oral rizatriptan 10 mg or placebo. Motion sickness was assessed using two standardized questionnaires. RESULTS: Motion sickness scores were lower following pre-treatment with rizatriptan compared with placebo in subjects with migrainous vertigo. Rizatriptan did not affect motion sickness in migraineurs without vertigo. Otolith-ocular reflex sensitivity was reduced following pretreatment with rizatriptan in both groups. CONCLUSIONS: This is the first study in humans testing a triptan serotonin agonist as a preventive tool for motion sickness. Rizatriptan prevented the development of motion sickness and severe motion sickness symptoms in patients with migrainous vertigo. These pilot data suggest a possible role for serotonin in the development of motion sickness symptoms in migraineurs with migrainous vertigo.

Adult↗
PubMed1986

Maldevelopment of visual motion processing in humans who had strabismus with onset in infancy.

Binocular experience in infancy is necessary for the normal development of the visual cortex. However, it is not known whether binocular experience also affects the processing of specific kinds of visual information such as motion. We now report deficits in visual motion processing in 7 adult humans who lacked binocularity in infancy because of strabismus. As probes for assessing visual motion processing, we used the initiation of smooth pursuit eye movements and the judgment of target velocity independent of eye movement. Monocular viewing was essential to reveal the deficits. For horizontal pursuit, strabismic subjects showed nasal-temporal asymmetries, such that nasally directed target motion evoked more vigorous pursuit. For vertical pursuit, strabismics showed up-down asymmetries, such that upward target motion evoked more vigorous pursuit. In addition, strabismics had abnormalities in the relative effectiveness of different parts of the visual field for initiating both horizontal and vertical pursuit. Psychophysical judgements of horizontal target velocity revealed deficits analogous motion was perceived as faster than temporally directed motion, even when the 2 directions of motion were actually presented at the same speed. The magnitude of the motion processing deficits in each subject was correlated with the severity of the clinical signs of the strabismus. Our results suggest 2 possible interpretations. Maldevelopments of visual motion processing may cause strabismus in infancy, or alternatively, strabismus in the critical period for visual development may cause a maldevelopment of visual motion processing.

Adult↗
PubMed1995

Response of monkey MST neurons to optic flow stimuli with shifted centers of motion.

Neurons in the dorsal region of the medial superior temporal area (MSTd) have previously been shown to respond to the expanding radial motion that occurs as an observer moves through the environment. In previous experiments, MSTd neurons were tested with radial and circular motion centered in the visual field. However, different directions of observer motion, relative to the direction of gaze, are accompanied by visual motion centered at different locations in the visual field. The present experiments investigated whether neurons that respond to radial and circular motion might respond differently when the center of motion was shifted to different regions of the visual field. About 90% of the 245 neurons studied responded differently when the center of motion was shifted away from the center of the field. The centers of motion preferred by each neuron were limited to one area of the visual field. All parts of the visual field were represented in the sample, with greater numbers of neurons preferring centers of motion closer to the center of the field. We hypothesize that each of the MSTd neurons has a center of motion field with a gradient of preferred centers of motion, and that there is an orderly arrangement of MSTd neurons with each region of the visual field being represented by a set of neurons. This arrangement creates the potential for graded responses from individual neurons for different directions of heading as an observer moves through the environment.

Animals↗
PubMed1999

[Comparison between motion sickness induced by reversed vision and that by parallel swing].

OBJECTIVE: To make clear the characteristics of motion sickness induced by reversed vision and to see whether it can be used in motion sickness experiments. METHODS: 10 healthy young men experienced walking tests wearing up-down or left-right reversing prisms, and parallel swing test on different days with intervals of 5-7d. Ataxia and motion sickness symptoms induced by walking wearing reversing prisms and those by parallel swing were observed. The reversed vision tolerance index (RVTI) and linear acceleration tolerance index (LATI) were calculated by an empirical formula. RESULTS: Both types of reversing prisms can induce obvious ataxia and motion sickness symptoms. The ataxia is correlative (P<0.05) with the susceptibility to motion sickness. In comparison with symptoms of swing motion sickness, the symptoms of reversed vision motion sickness are not too serious and appear slowly. There are correlativities (P< 0.01) between the susceptibility to motion sickness induced by up-down and left-right reversing prisms. The susceptibilities to motion sickness induced by reversing prisms are not correlative completely with that by swing. CONCLUSION: Reversed vision test is simple and easy and can be used for simulating space motion sickness or training of adaptation to sensory conflict on the ground.

Acceleration↗
PubMed2007

Early effects of coronary artery bypass grafting on left ventricular regional wall motion abnormalities.

OBJECTIVE: To determine the early effects of Coronary Artery Bypass Grafting (CABG) on regional left ventricular wall motion abnormality in patients undergoing surgery for proven Coronary Artery Disease (CAD). DESIGN: Quasi-experimental study. PLACE AND DURATION OF STUDY: Department of Cardiac Surgery, National Institute of Cardiovascular Diseases, Karachi. from October 2005 to April 2006. PATIENTS AND METHODS: A total of a 100 adult patients who underwent elective CABG were selected. Pre-operative echocardiography was done to note if segmental left ventricular wall motion at basal, mid and apical levels were normal, hypokinetic, akinetic, dyskinetic, or aneurysmal. Postoperative echocardiography was done between 4th and 6th day and change in left ventricular segmental wall motion was noted. RESULTS: Seventy-five patients (n=75) were included in the analysis. These results showed that effect of CABG on anterior segmental wall motion abnormalities was insignificant (p=.609), the effect on the anterior IVS showed deterioration of segmental wall motion and this effect was significant (p=.001), effect is insignificant on anteriolateral segmental wall motion abnormalities (p=.078), normal pre-operative segments in posterior wall showed stability (p=.664) while disappearance of dyskinetic, reduction in akinetic segments postoperatively and inferior wall motion have same effects as of posterior wall. Comparison of pre-operative and postoperative echocardiographic data revealed early improvement in segmental wall motion of posterior and inferior wall, while alterations in segmental wall motion of anterior, anterior-lateral and septal wall. CONCLUSION: Myocardial revascularization by CABG improves early left ventricular regional wall motion abnormalities where SVG is used as conduit for revascularization whereas no significant improvement occurs in early segmental wall motion in areas revascularized by LIMA.

Adult↗
PubMed2003

Additive value of low-dose dobutamine to technetium-99m sestamibi-gated single-photon emission computed tomography for prediction of wall motion improvement in patients undergoing coronary artery bypass graft.

BACKGROUND: The two most useful methods for myocardial viability assessment are perfusion imaging and dobutamine echocardiography. HYPOTHESIS: The present study investigated the additive value of a new method, dobutamine technetium 99m (99mTc)-sestamibi-gated single-photon emission computed tomography (SPECT), which combines these two modalities, to the prediction of wall motion improvement after revascularization. METHODS: Fifty-five consecutive patients with ischemic cardiomyopathy, who were referred for viability evaluation, underwent resting and dobutamine (dose, 5-10 microkg/kg/min) gated SPECT with 99mTc-sestamibi. Of these patients, 36 underwent coronary artery bypass graft (CABG) within 1 month of the study and 32 had repeat resting gated SPECT within 1 year. Global and regional wall motion, wall thickness, and perfusion were simultaneously analyzed at rest and after dobutamine using the 20-segment model; the sestamibi uptake and wall motion response to dobutamine of each segment were rated quantitatively. Based on these findings, the segments were categorized as normal, viable, or nonviable. The predictive values for wall motion improvement were assessed by perfusion, using cutoffs of 50 and 60% of sestamibi uptake, and thereafter by the addition of dobutamine response in the segments that were rated nonviable. RESULTS: Of the 1,080 myocardial segments studied, 906 (84%) had abnormal wall motion and were analyzed for viability. Concordance between perfusion and wall motion response to dobutamine was 60% with the 50% cutoff of sestamibi uptake, and increased to 65% with the 60% sestamibi cutoff (p < 0.04). The respective predictive values of wall motion improvement using the 50 and 60% cutoff points were as follows: sensitivity 93 and 70%, respectively, (p < 0.01); specificity 59 and 86% (p < 0.001), respectively; accuracy 77% for both. The addition of the wall motion response to dobutamine to the assessment of the nonviable segments by perfusion (60% cutoff) increased the sensitivity from 70 to 85% (p = 0.001) and the negative predictive value from 70 to 81% (p = 0.009); the positive predictive value remained high (86 vs. 82%). No additive value of wall motion response to dobutamine was demonstrated for nonviable segments by perfusion with a 50% cutoff. CONCLUSION: Dobutamine sestamibi-gated SPECT is a feasible method for the analysis of myocardial perfusion, function, and contractile reserve of individual myocardial segments in patients with ischemic cardiomyopathy. Viability assessment based on a threshold of 60% uptake of sestamibi, with the addition of the wall motion response to dobutamine in the nonviable segments, seems to yield better predictive values for wall motion improvement after CABG.

Aged↗
PubMed1999

Hamstring graft motion in the femoral bone tunnel when using titanium button/polyester tape fixation.

The objective of this study was to determine the relative motion of a quadruple hamstring graft within the femoral bone tunnel (graft-tunnel motion) under tensile loading. Six graft constructs were prepared from the semitendinosus and gracilis tendons of human cadavers and were fixed with a titanium button and polyester tape within a bone tunnel in a cadaveric femur. Three different lengths of polyester tape (15, 25, and 35 mm loops) were evaluated. The femur was held stationary and uniaxial tensile loads were applied to the distal end of the graft using a materials testing machine. Each construct was subjected to loading for ten cycles with upper limits of 50 N, 100 N, 200 N and 300 N. Graft-tunnel motion was then determined using the distances between reflective tape markers placed on the hamstring graft and at the entrance to the femoral bone tunnel, which were tracked with a high-resolution video system. Graft-tunnel motion was found to range from 0.7 +/- 0.2 mm to 3.3 +/- 0.2 mm, and significant increases in graft-tunnel motion were observed with increasing tensile loads (P < 0.05). Shorter tape length (15 mm) resulted in significantly less motion when compared to longer tape length (35 mm) (P < 0.05). We conclude that graft-tunnel motion is significant and should be considered when using this fixation technique. Early stress on the graft, as seen in postoperative rehabilitation exercises and athletic activities, may cause large graft-tunnel motion before graft incorporation is complete. A shorter distance between the tendon tissue and the titanium button is recommended to minimize the amount of graft-tunnel motion. Alternative fixation materials to polyester tape, or different fixation techniques, need to be developed such that graft-tunnel motion can be reduced. Further studies are needed to evaluate the effect of graft-tunnel motion on graft incorporation in the bone tunnel.

Biomechanical Phenomena↗
PubMed2001

Detection of residual wall motion after myocardial infarction by gated technetium-99m tetrofosmin SPET: a comparison with contrast ventriculography.

The differentiation of residual viability from necrotic myocardium in patients with a prior myocardial infarction is important when deciding whether revascularization is indicated. Myocardial viability can be assessed by studying perfusion and regional wall motion. Gated single-photon emission tomography (SPET) imaging allows the simultaneous assessment of perfusion and function through a single study. The aim of this study was to analyse the concordance between wall motion score derived by gated SPET and by contrast ventriculography. Furthermore, the agreement between myocardial perfusion and regional myocardial wall motion was analysed for both techniques. We studied a homogeneous group of 26 consecutive patients with a prior myocardial infarction, using both gated technetium-99m tetrofosmin SPET and contrast ventriculography. A seven-segment model of the left ventricle was employed to score regional myocardial wall motion on images obtained with gated SPET and contrast ventriculography using a four-point scale. Contrast ventriculography was performed within 2 weeks of the gated SPET study. Prevalence of abnormal wall motion (akinetic or dyskinetic) was 24/182 (13%) for gated SPET and 25/182 (14%) for contrast ventriculography (P = NS). There was a high agreement (80%) in wall motion score between gated SPET and contrast ventriculography (kappa = 0.67, P < 0.001). The agreement was better in segments with normal or mild to moderate hypoperfusion (82%, kappa = 0.69) than in those with severe hypoperfusion (67%, kappa = 0.56). The agreement between myocardial perfusion and myocardial wall motion was 89% (162/182), kappa = 0.57, for gated SPET and 80% (145/182), kappa = 0.21, for contrast ventriculography. The relation between the summed wall motion scores per patient on gated SPET and contrast ventriculography was excellent (y = 0.81x + 2.9, r = 0.82, P < 0.01). Thirteen (43%) out of 30 segments with severely diminished or no myocardial perfusion showed normal or hypokinetic wall motion on gated SPET, suggesting residual myocardial viability in malperfused regions. Our results suggest that gated SPET imaging is a reliable tool for the assessment of regional wall motion in post-myocardial infarction patients. Furthermore, in patients with a previous myocardial infarction, gated SPET imaging has the potential to detect preserved wall motion in regions with fixed perfusion defects, which might be indicative of residual myocardial viability.

Adult↗
PubMed2006

Systolic anterior motion after mitral valve repair: is surgical intervention necessary?

OBJECTIVE: The natural history and management of patients with systolic anterior motion after mitral valve repair are uncertain. METHODS: We performed a retrospective chart review and survey follow-up of all patients in whom systolic anterior motion developed intraoperatively after mitral valve repair. RESULTS: From January 1993 to December 2002, mitral valve repair was performed in 2076 patients, and in 174 cases (8.4%) systolic anterior motion was identified on intraoperative echocardiography. These patients form the study group. Initially, patients were managed with a combination of beta-blockade, vasoconstriction with phenylephrine, and/or intravascular volume expansion. Four patients had revision of repair because of persistent systolic anterior motion, and 3 additional patients had revision of repair because of mitral regurgitation from other causes. The median follow-up of the remaining 167 patients was 5.4 years (range 0-13.2 years). There were 2 late reoperations, but none were caused by systolic anterior motion or left ventricular outflow tract obstruction. Ninety percent of patients were in New York Heart Association class I, 7% were in class II, and 3% were in class III or IV. Echocardiograms were available for review in 93 patients at a median interval of 5.4 years (range 0.2-12.2 years); 13 patients had systolic anterior motion, and 4 patients had systolic anterior motion with left ventricular outflow tract obstruction. CONCLUSIONS: In this experience, most cases of systolic anterior motion resolved with conservative measures including beta-blockade, vasoconstriction, and fluid administration. Persistent systolic anterior motion with left ventricular outflow tract obstruction was documented in 2.3% of patients who had early systolic anterior motion, but late reoperation was not required. Furthermore, the clinical outcomes of patients with systolic anterior motion are comparable to the current norms for mitral valve repair. Ninety percent of patients were in New York Heart Association class I, 7% were in class II, and 3% were in class III or IV.

Adult↗
PubMed1993

Abnormal postoperative interventricular motion: new intraoperative transesophageal echocardiographic evidence supports a novel hypothesis.

Abnormal interventricular septal motion is a frequent finding after cardiac surgery. However, the time course and underlying mechanisms are not well understood. Nineteen patients, mean age 54 years (range 20 to 82 years), were studied with intraoperative transesophageal echocardiography at five specific times: with the chest closed (baseline), with the chest open and the pericardium closed, with both chest and pericardium open, after cardiopulmonary bypass with the chest open, and after cardiopulmonary bypass with the chest closed. In each patient interventricular septal motion was recorded from the transgastric view; tricuspid annular motion and Doppler color flow mapping of tricuspid regurgitation were obtained from the four-chamber view. All the echocardiographic data were stored on videotape and were later viewed in random sequence by one investigator who was aware of the baseline stage but was blinded to the other stages. All patients had normal septal motion before cardiopulmonary bypass. After cardiopulmonary bypass, with the chest still open, 5 of 17 patients (29%) with adequate recordings had abnormal septal motion while 13 of 17 patients (76%) with adequate recordings had abnormal tricuspid annular motion. After chest closure, only three patients (14%) had normal septal motion and one patient (6%) had normal tricuspid annular motion. Significant tricuspid regurgitation was an infrequent finding in all cases. It is concluded that abnormal interventricular septal motion occurs after cardiopulmonary bypass and is related to abnormal tricuspid annular motion. We hypothesize that suboptimal right ventricular myocardial preservation impairs the motion pattern of the right ventricle, including the tricuspid annulus.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1997

Evaluation of color kinesis, a new echocardiographic method for analyzing regional wall motion in patients with dilated left ventricles.

The recently developed echocardiographic technology of color kinesis (CK) displays endocardial motion in color layers on a single end-systolic 2-dimensional echocardiographic frame. Previous work using this method is promising for quantitation of regional function, but there is limited experience in patients with severely reduced left ventricular function. Twenty patients (age 59 +/- 10 years) with dilated cardiomyopathy (left ventricular ejection fraction 22 +/- 8%) underwent CK imaging. Endocardial motion was quantitated by measuring the distance of endocardial motion during the systolic interval and also by calculating the endocardial velocity. CK measurements were compared among 4 wall motion grades (i.e., normal, hypokinetic, akinetic, and dyskinetic) assessed by qualitative wall motion scoring. There was a significant overall difference (p < 0.0001) in the mean systolic endocardial inward motion (i.e., contraction) and outward motion (i.e., expansion) among wall motion grades. The mean endocardial outward distance was significantly greater for the dyskinetic segments than for the other grades (p < 0.001). There were also differences in the mean velocity of endocardial motion among the wall motion grades. In the presence of left bundle branch block, there was no difference in the mean endocardial inward distance of the hypokinetic, akinetic, and dyskinetic septal segments. We conclude that in the absence of left bundle branch block, normal, hypokinetic, akinetic, and dyskinetic ventricular wall segments may be distinguished in patients with dilated cardiomyopathy on the basis of endocardial motion measured with CK.

Bundle-Branch Block↗
PubMed2002

Motion artifacts in scanning laser polarimetry.

PURPOSE: The GDx (Laser Diagnostic Technologies, San Diego, CA) is a scanning laser polarimeter that measures retardation to assess retinal nerve fiber layer thickness in vivo. Eye movements during image acquisition may result in motion artifacts in the GDx image. The aims of this study were to investigate the effect of motion artifacts on the retardation values and to illustrate how motion artifacts can be identified. DESIGN: Observational case series. PARTICIPANTS: Thirty-two normal subjects and 28 glaucoma patients participated. METHODS: We imaged all 60 subjects with the GDx. Images with identified motion artifacts were compared with images without motion artifacts from the same eye and the same session. In 25 cases, the artifact was identified in the superior segment only, and the effect on the superior maximum parameter was calculated. In 26 cases, the artifact was observed in the inferior segment only, and the effect on the inferior maximum parameter was calculated. In nine cases, the artifact was observed superiorly and inferiorly, and the effect on both parameters was calculated. In all 60 cases, the effect on The Number (a summary parameter) was calculated. We also analyzed the groups of glaucoma patients and normal subjects separately. MAIN OUTCOME MEASURES: Superior maximum parameter, inferior maximum parameter, The Number parameters. RESULTS: In general, the identified motion artifacts led to an increase in retardation, reflected by an increase in the superior maximum and inferior maximum parameter by 5.9 micro m and 3.4 micro m, respectively (P < 0.001). The Number decreased by 3.4 with motion artifacts (P = 0.001). The variability of this effect was large. In one case, the motion artifact increased retardation by as much as 28.6 micro m. The effect of motion artifacts was greater in glaucoma patients than in normal subjects. CONCLUSIONS: The identified motion artifacts generally increase retardation values. This increase, however, is highly variable. Therefore, images with such motion artifacts should be viewed with caution or excluded from analysis.

Adult↗
PubMed2000

The effects of motion on trunk biomechanics.

OBJECTIVE: To review the literature that evaluates the influence of trunk motion on trunk strength and structural loading. BACKGROUND: In recent years, trunk dynamics have been identified as potential risk factors for developing low-back disorders. Consequently, a better understanding of the underlying mechanisms involved in trunk motion is needed. METHODS: This review summarizes the results of 53 studies that have evaluated trunk motion and its impact on several biomechanical outcome measures. The biomechanical measures consisted of trunk strength, intra-abdominal pressure, muscle activity, imposed trunk moments, and spinal loads. Each of these biomechanical measures was discussed in relation to the existing knowledge within each plane of motion (extension, flexion, lateral flexion, twisting, and asymmetric extension). RESULTS: Trunk strength was drastically reduced as dynamic motion increased, and males were impacted more than females. Intra-abdominal pressure seemed to only be affected by trunk dynamics at high levels of force. Trunk moments were found to increase monotonically with increased trunk motion. Both agonistic and antagonistic muscle activities were greater as dynamic characteristics increased. As a result, the three-dimensional spinal loads increase significantly for dynamic exertions as compared to isometric conditions. CONCLUSIONS: Trunk motion has a dramatic affect on the muscle coactivity, which seems to be the underlying source for the decrease strength capability as well as the increased muscle force, IAP, and spinal loads. This review suggests that the ability of the individual to perform a task "safely" might be significantly compromised by the muscle coactivity that accompanies dynamic exertions. It is also important to consider various workplace and individual factors when attempting to reduce the impact of trunk motions during dynamic exertions. Relevance This review provides insight as to why trunk motions are important risk factors to consider when attempting to control low-back disorders in the workplace. It is apparent that trunk motion increases the risk of low-back disorders. To better control low-back disorders in industry, more comprehensive knowledge about the impact of trunk motion is needed. A better understanding of muscle coactivity may ultimately lead to reducing the risk associated with dynamic exertions.

Abdomen↗
PubMed2000

Attentional modulation of visual motion perception.

How is the perception and processing of visual motion affected by attention? This review examines recent research in cognition, perception and neurophysiology that explores how ongoing behavioural tasks (and the attentional states they impose) modulate the processing of visual motion. Although traditional views hold that motion is processed in an obligatory, 'pre-attentive' manner, evidence for processing in a task-independent manner is scant. Recent studies of human perception that have measured motion priming, motion aftereffects, uncertainty effects, and motion-interaction effects indicate instead that even simple aspects of motion processing may be substantially affected by whether motion information in a task is used or ignored by the perceiver. Single-unit studies in brain areas sensitive to visual motion in monkeys, and functional imaging studies on humans, also indicate that task and attentional state affect activity levels in brain regions thought to be important in motion perception. This review brings together these converging findings of attentional modulation of motion perception and considers them in light of object-oriented theories of attention.

Journal Article↗
PubMed1990

Regulation of anaphase chromosome motion in Tradescantia stamen hair cells by calcium and related signaling agents.

Several lines of evidence support the idea that increases in the intracellular free calcium concentration [( Ca2+]i) regulate chromosome motion. To directly test this we have iontophoretically injected Ca2+ or related signaling agents into Tradescantia stamen hair cells during anaphase and measured their effect on chromosome motion and on the Ca2+ levels. Ca2+ at (+)1 nA for 10 s (approximately 1 microM) causes a transient (20 s) twofold increase in the rate of chromosome motion, while at higher levels it slows or completely stops motion. Ca2+ buffers, EGTA, and 5,5'-dibromo-1,2- bis(o-aminophenoxy)ethane-N,N,N',N'-tetraacetic acid, which transiently suppress the ion level, also momentarily stop motion. Injection of K+, Cl-, or Mg2+, as controls, have no effect on motion. The injection of GTP gamma S, and to a lesser extent GTP, enhances motion similarly to a low level of Ca2+. However, inositol 1,4,5-trisphosphate, ATP gamma S, ATP, and GDP beta S have no effect. Measurement of the [Ca2+]i with indo-1 reveals that the direct injections of Ca2+ produce the expected increases. GTP gamma S, on the other hand, causes only a small [Ca2+]i rise, which by itself is insufficient to increase the rate of chromosome motion. Further studies reveal that any negative ion injection, presumably through hyperpolarization of the membrane potential, generates a similar small pulse of Ca2+, yet these agents have no effect on motion. Two major conclusions from these studies are as follows. (a) Increased [Ca2+]i can enhance the rate of motion, if administered in a narrow physiological window around 1 microM; concentrations above 1 microM or below the physiological resting level will slow or stop chromosomes. (b) GTP gamma S enhances motion by a mechanism that does not cause a sustained uniform rise of [Ca2+]i in the spindle; this effect may be mediated through very localized [Ca2+]i changes or Ca2(+)-independent effectors.

Adenine Nucleotides↗
PubMed1983

'Pseudo' systolic anterior motion in patients with hypertensive heart disease.

The systolic motion of the mitral apparatus in patients with hypertensive heart disease and hypertrophic cardiomyopathy was studied in order to quantify the difference. Twelve out of 37 patients with severe systemic hypertension were found to have abnormal systolic anterior motion and had significantly small left ventricular end-systolic dimension (P less than 0.05) and greater ejection fraction and mean velocity of circumferential fibre shortening (P less than 0.01 for each) than the other hypertensive patients without abnormal systolic anterior motion. A comparison between systolic anterior motion in 12 hypertensive patients and mild or moderate systolic anterior motion in 28 patients with hypertrophic cardiomyopathy showed a clear cut difference. 'Pseudo' systole anterior motion reached its peak at end-systole when the posterior wall had contracted fully. 'True' systolic anterior motion, however, reached its peak much earlier than maximum movement of the posterior wall--approximately after two-thirds of systole had been completed. At the time of mitral valve opening, 'pseudo' systolic anterior motion had not yet returned to this initial level, whereas 'true' systolic anterior motion returned prior to the opening of the mitral valve. Anterior chordal motion in hyperdynamic ventricle appears to play a role in the production of 'pseudo' systolic anterior motion.

Adolescent↗
PubMed2001

Assessment of regional myocardial wall motion and thickening by gated 99Tcm-tetrofosmin SPECT: a comparison with magnetic resonance imaging.

Gated single photon emission computed tomography (SPECT) imaging allows the simultaneous assessment of both perfusion and function by using one single study. The assessment of regional wall motion and thickening pattern with gated SPECT allows viability studies to be performed. Magnetic resonance imaging (MRI) is well validated for the assessment of myocardial wall motion and thickening in patients with normal and impaired ventricular function. The aim of the study was to analyse the concordance between wall motion and thickening scores derived by gated SPECT and MRI imaging. Furthermore, the agreement for myocardial wall motion and thickening according to myocardial perfusion was analysed with both techniques. We studied a group of 21 patients, including 13 with a previous myocardial infarction (all more than 4 months before the study), using both gated SPECT 99Tcm-tetrofosmin myocardial perfusion imaging and MRI. A 13-segment model was used for both gated SPECT and MRI and each segment was visually scored using a scale of 1-3 for wall motion and thickening. There was a high agreement between gated SPECT and MRI for both wall motion (229/273, 84%; k = 0.72, P<0.001) and wall thickening (236/273, 86%; k = 0.77, P<0.001). The agreement for wall motion and thickening was 80% (k = 0.66) and 83% (k = 0.70), respectively, for patients with myocardial infarction; and 90% (k = 0.81) and 92% (k = 0.86), respectively (P = NS), for patients without myocardial infarction. Agreement in segmental wall motion and thickening scores between gated SPECT and MRI was 90% (k = 0.80) and 91% (k = 0.84), respectively, for segments with normal or mild to moderate hypoperfusion; and 71% (k = 0.45) and 77% (k = 0.57), respectively, for segments with severe hypoperfusion or no perfusion. Of the 70 (41%) segments that had severely diminished or no perfusion in post-myocardial infarction patients, 22 (31%) showed preserved wall motion and 17 (24%) showed preserved wall thickening both by gated SPECT and MRI, suggesting residual myocardial viability in malperfused segments. Our results suggest that gated SPECT imaging is a reliable tool for the assessment of regional wall motion and thickening in patients with known or suspected coronary artery disease. In patients with a previous myocardial infarction gated SPECT imaging has the potential to detect preserved wall motion and thickening in regions with fixed perfusion defects indicating the potential presence of residual myocardial viability.

Adult↗
PubMed2001

Slow and fast visual motion channels have independent binocular-rivalry stages.

We have previously reported a transparent motion after-effect indicating that the human visual system comprises separate slow and fast motion channels. Here, we report that the presentation of a fast motion in one eye and a slow motion in the other eye does not result in binocular rivalry but in a clear percept of transparent motion. We call this new visual phenomenon 'dichoptic motion transparency' (DMT). So far only the DMT phenomenon and the two motion after-effects (the 'classical' motion after-effect, seen after motion adaptation on a static test pattern, and the dynamic motion after-effect, seen on a dynamic-noise test pattern) appear to isolate the channels completely. The speed ranges of the slow and fast channels overlap strongly and are observer dependent. A model is presented that links after-effect durations of an observer to the probability of rivalry or DMT as a function of dichoptic velocity combinations. Model results support the assumption of two highly independent channels showing only within-channel rivalry, and no rivalry or after-effect interactions between the channels. The finding of two independent motion vision channels, each with a separate rivalry stage and a private line to conscious perception, might be helpful in visualizing or analysing pathways to consciousness.

Humans↗