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PubMed2006

Determinants of rapid progression of aortic root dilatation and complications in Marfan syndrome.

BACKGROUND: Progressive aortic dilatation has prognostic significance in the Marfan syndrome. METHODS: To identify which patients were at high risk of rapid progression, we echocardiographically studied 43 patients (age 22 +/- 14 years) with the mean follow-up period of 5.2 +/- 3.2 years. Aortic diameters, left ventricular (LV) size, fractional shortening, and the severity of aortic and mitral regurgitation were assessed. Transmitral peak early and atrial flow velocities, their ratio and the deceleration time of peak early velocity were also obtained. RESULTS: Mean annual increases of aortic diameters were 0.4 +/- 0.3 mm at the annulus, 1.5 +/- 1.3 mm at the sinuses of Valsalva, 0.7 +/- 0.6 mm at the supraaortic ridge and 0.4 +/- 0.4 mm at the proximal ascending aorta. Patients were divided into 2 groups according to the aortic growth rate at the sinuses of Valsalva level: rapid (R, >3% per year, 15 patients) or slow (S, < or =3% per year, 28 patients) progression groups. Measured variables did not show significant differences between the 2 groups except older age, higher blood pressure and more severe aortic regurgitation in group R. Multiple regression analysis identified prolonged deceleration time as the most important variable predicting aortic complications. Aortic dissection occurred more frequently in group R (7 patients, 47%) than in group S (0%, P < 0.001). CONCLUSIONS: Marfan patients at older age, with higher blood pressure, and with significant aortic regurgitation were at high risk of progression of aortic dilatation, with the most remarkable increase at the sinuses of Valsalva. Prolonged deceleration time may relate to an increased risk for aortic complications.

Adolescent↗
PubMed2005

Echocardiographic predictors of morbidity and mortality in patients with advanced heart failure: the Beta-blocker Evaluation of Survival Trial (BEST).

OBJECTIVES: The aim of this study was to determine echocardiographic predictors of outcome in patients with advanced heart failure (HF) due to severe left ventricular (LV) systolic dysfunction in the Beta-blocker Evaluation of Survival Trial (BEST). BACKGROUND: Previous studies indicate that echocardiographic measurements of LV size and function, mitral deceleration time, and mitral regurgitation (MR) predict adverse outcomes in HF. However, complete quantitative echocardiograms evaluating all of these parameters have not been reported in a prospective randomized clinical trial in the era of modern HF therapy. METHODS: Complete echocardiograms were performed in 336 patients at 26 sites and analyzed by a core laboratory. A Cox proportional-hazards regression model was used to determine which echocardiographic variables predicted the primary end point of death or the secondary end point of death, HF hospitalization, or transplant. Significant variables were then entered into a multivariable model adjusted for clinical and demographic covariates. RESULTS: On multivariable analysis adjusted for clinical covariates, only LV end-diastolic volume index predicted death (events = 75), with a cut point of 120 ml/m(2). Three echocardiographic variables predicted the combined end point of death (events = 75), HF hospitalization (events = 97), and transplant (events = 9): LV end-diastolic volume index, mitral deceleration time, and the vena contracta width of MR. Optimal cut points for these variables were 120 ml/m(2), 150 ms, and 0.4 cm, respectively. CONCLUSIONS: Echocardiographic predictors of outcome in advanced HF include LV end-diastolic volume index, mitral deceleration time, and vena contracta width. These variables indicate that LV remodeling, increased LV stiffness, and MR are independent predictors of outcome in patients with advanced HF.

Echocardiography, Doppler↗
PubMed2006

Quantification of the input signal for soft tissue vibration during running.

Soft tissue compartment vibrations are initiated at heel-strike in heel-toe running. The concept of muscle tuning suggests that the body tries to minimize these vibrations with a muscle adaptation that changes the mechanical properties of the soft tissue compartment. A muscle tuning adaptation can be quantified by determining the biodynamic response, of the soft tissue compartment for different experimental conditions. To determine the biodynamic response a measure of both the input signal and the soft tissue compartment vibrations are required. The input signal for the vibrations is the rapid deceleration of the leg after initial ground contact. The aim of this study was to evaluate three non-invasive methods to quantify the input signal for the triceps surae soft tissue vibrations. Data from a force platform, a shoe mounted accelerometer and a video analysis of a reflective skin marker were used to quantify leg deceleration. Both the shoe mounted accelerometer and skin marker method provided a satisfactory evaluation of the input signal and could be used to determine the biodynamic response of the soft tissue compartment. The impact portion of the ground reaction force is primarily due to the deceleration of the leg at landing. However, due to the influence of the effective body mass on the impact magnitude, the force plate data was not appropriate for quantifying a muscle tuning response.

Computer Simulation↗
PubMed2005

The association between later cortical potentials and later phases of postural reactions evoked by perturbations to upright stance.

Previous studies have suggested that early cortical potentials (e.g. N1) that are evoked by perturbations to upright stance are associated with sensory processing of the initial perturbation and that later potentials may represent cognitive processing of this perturbation. However, it has also been suggested that later cortical potentials could reflect sensory and motor processing of later phases of the postural reaction. The current study set out to provide additional insight into the association between perturbation-evoked cortical potentials and postural reactions evoked by whole-body perturbations. By altering the deceleration onset of the perturbation, which altered the timing of later postural responses, we determined whether changes in later postural responses were associated with changes in later potentials. Based on previous work, we hypothesized that later potentials would not be associated with changes in later postural responses. During stance, seven healthy young adults were instructed to maintain their balance following two types of perturbations: (1) acceleration phase immediately followed by a deceleration phase (TASK 1), and (2) acceleration phase followed by a delayed deceleration phase (TASK 2). In spite of profound task differences in later postural responses, results revealed no significant differences in later potentials. This work provides additional support for the idea that latter elements of perturbation-evoked cortical responses are likely independent of evoked motor reactions required to maintain stability.

Adult↗
PubMed2006

Modelling instantaneous traffic emission and the influence of traffic speed limits.

This paper considers the effect of active speed management on traffic-induced emissions. In particular, the traffic emissions caused by acceleration and deceleration of vehicles are modelled based on an instantaneous emission model integrated with a microscopic traffic simulation model. The emission model is based on empirical measurements which relate vehicle emission to the type, the instantaneous speed and acceleration of the vehicle. The traffic model captures the second-by-second speed and acceleration of individual vehicles travelling in a road network based on their individual driving style, the vehicle mechanics, and their interaction with other traffic and with traffic control in the network. The integrated model is applied to test a new technology to actively manage the driving speed of the vehicles in an urban network. Their impacts on vehicle emission in the network are assessed to give an indication of the relative effectiveness of the different technological designs and different levels of driver responses. The results show that, while the speed management has effectively reduced the average speed of the traffic, their impact on vehicle emissions is complex. For the study network, the frequent acceleration and deceleration movements in the network has significantly reduced the effect of the reduced average speed on emission. The net results are that the active speed management has no significant impact on pollutant emissions. The study suggests that the analysis of the environmental impacts of any traffic management and control policies is a complex issue and requires detailed analysis of not only their impact on average speeds but also on other aspects of vehicle operation such as acceleration and deceleration.

Air Pollutants↗
PubMed2003

Prehension in young children with Down syndrome.

Prehension was examined in 3-year old children with Down syndrome (DS, n = 3) and in typically-developing children matched in chronological age (3-year olds; n = 3) or mental age and motor experience (2-year olds; n = 3). The task required reaching to grasp dowels. Video-based movement analysis yielded temporal and kinematic measures. Children with DS were hypothesized to have deficits in feedback-dependent components of prehension (anticipatory grip-closure and deceleration of reach), whereas feedforward components (reach's acceleration phase; grasp's preshaping) were assumed to be unimpaired [Latash, 1993, Control of human movement, pp. 283-292; Latash, 1994, What is clumsiness? In: Motor Control and Down Syndrome II Proceedings of the second international conference, pp. 68-71]. The findings supported these hypotheses. In comparison to control groups, children with DS had significantly: (a) less time in deceleration of reaching, (b) fewer anticipatory grip-closures, and (c) longer movement times for dowel-lift. Young children with DS appeared to use dowel-contact to decelerate the limb and initiate grip-closure. In contrast, reach-acceleration time and grasp-preshaping did not differ across groups. These findings suggest that children with DS display qualitative differences in motor capabilities rather than simply a delayed rate of typical developmental progression.

Child, Preschool↗
PubMed1997

Right and left ventricular diastolic function in patients with and without heart failure: effect of age, sex, heart rate, and respiration on Doppler-derived measurements.

Doppler echocardiography is widely used to assess right and left ventricular diastolic function. Although the factors affecting Doppler-derived measurements have been described in unaffected patients, there is little information available for patients with heart failure. Therefore we performed two-dimensional Doppler echocardiography studies of right and left ventricular function in 140 subjects, 88 with congestive heart failure and 52 age-matched normal subjects. The separate effects of age, sex, heart rate, and respiration were assessed by correlation analysis and multiple linear regression. In normal subjects both left and right ventricular parameters significantly correlated with age and heart rate. No significant effect of respiration was apparent in left ventricular function, but in the right ventricle inspiration caused a significant increase in transtricuspid peak E-wave velocity, E/A ratio, and shortening of the E-wave deceleration time. There was a significant correlation between left and right ventricular diastolic parameters. In heart failure, age correlated weakly with mitral valve peak A wave (r = 0.23, p = 0.03) and with tricuspid valve peak E-wave velocity (r = 0.37, p < 0.001), although in those with a restrictive filling pattern age was associated with a significant increased shortening of the mitral E-wave deceleration time (r = -0.8; p = 0.0015). Heart rate and deceleration time of mitral and tricuspid E wave significantly correlated, but heart rate did not correlate with either mitral or tricuspid peak E-wave or A-wave velocities or E/A ratio. In heart failure the effect of respiration was similar to normal subjects. Sex was not associated with Doppler variables in either normals or heart failure subjects. Thus this study demonstrates that age, heart rate, and respiration have important and separate associations with Doppler echo diastolic parameters of the right and left ventricle in normal subjects and similar, although weaker relations in patients with heart failure.

Adult↗
PubMed1996

Serial assessment of left ventricular chamber stiffness after acute myocardial infarction.

Left ventricular (LV) systolic function after acute myocardial infarction (AMI) has been the subject of detailed studies during the last decade, but diastolic phenomena during and after AMI are less well understood. Recently, it has been shown that early filling deceleration time accurately predicted LV chamber stiffness in an experimental model. To assess changes of LV stiffness after AMI, we studied 116 consecutive patients with 2-dimensional and Doppler echocardiographic examinations 1, 2, 3, 7, 21, and 42 days after AMI. Coronary angiography was performed in 101 patients. For the entire study group, deceleration time decreased nonsignificantly on day 2 and subsequently increased on days 3 (p = 0.001) and 7 (p = 0.036), returning toward initial values afterward. Deceleration time was shorter in large (peak creatine kinase level >1,000 U/L) versus small infarcts (p = 0.0008) and in patients with anterior versus inferior AMI (p = 0.02); there was no difference between patients with good and poor (< or = 45%) ejection fraction. These data indicate that increased LV stiffness can be detected 24 to 48 hours after AMI, but returns to normal within several days. Chamber stiffness is higher in large and anterior infarcts, but appears to be independent of LV systolic function.

Aged↗
PubMed1999

Prognostic value of diastolic filling parameters derived using a novel image processing technique in patients > or = 70 years of age with congestive heart failure.

Conventional echocardiographic characterization of diastolic function requires manual analysis of Doppler E-and A-wave amplitudes, deceleration times, isovolumic relaxation times, and pulmonary venous flow patterns. Mathematic modeling of the suction pump activity of the heart permits characterization of diastolic function through model-based image processing, which relies solely on transmitral Doppler images. This automated method uniquely specifies the entire E-wave contour using 3 parameters (x(o), k, and c) that determine E-wave amplitude, width, and rate of decay. Moreover, the index beta = c2 - 4k, reflecting the balance between chamber viscosity and stiffness/recoil, represents a novel parameter for characterizing diastolic function. We analyzed Doppler E waves from 39 patients (mean age 79 years, 61% women, mean ejection fraction 47%) using the model-based image processing technique. A value of beta <-900 was selected as indicative of severe diastolic dysfunction. Of 17 subjects with beta <-900, 8 (47%) were no longer alive at 1 year. Of 22 subjects with beta >-900, all were alive (p = 0.001). The index beta, dichotomized at <-900, had a predictive accuracy of 0.769 (30 of 39), a negative predictive value of 1.0 (22 of 22 alive), and a positive predictive value of 0.471 (8 of 17 deceased) for 1-year vital status. Of 14 subjects with deceleration time < or =160 ms, 5 (36%) were deceased at 1 year, whereas for deceleration time >160 ms, 22 of 25 patients were alive (p = NS). Of 16 subjects with ejection fraction <45%, 6 (38%) were deceased at 1 year. Of 23 subjects with ejection fraction >45%, 21 were alive at 1 year (p = 0.074). On multivariate analysis, beta dichotomized at -900 was the strongest independent predictor of 1-year mortality. We conclude that evaluation of diastolic function using model-based image processing provides valuable prognostic information in elderly patients with heart failure.

Aged↗
PubMed2000

Usefulness of left ventricular mass in predicting recovery of left ventricular systolic function in patients with symptomatic idiopathic dilated cardiomyopathy.

Prognosis of idiopathic dilated cardiomyopathy (IDC) is variable. We determined the prognostic value of left ventricular (LV) mass and systolic and diastolic function in patients with IDC of <12 months duration. Clinical and echocardiographic assessment was performed at baseline and at 8+/-6 months follow-up in 25 patients (47+/-13 years) with IDC and an LV ejection fraction (LVEF1) of <40% (22+/-7%). Based on a follow-up LVEF (LVEF2) of < or >40%, patients were divided into unimproved (n = 13, LVEF2 = 21+/-9%) and improved groups (n = 12, LVEF2 = 51+/-11%). There was no difference in the LVEF1 (22+/-8% vs. 22+/-6%), LV end-systolic (5.7+/-0.8 vs. 5.8+/-0.9 cm) or end-diastolic (6.5+/-0.6 vs. 6.6+/-0.9 cm) dimension, wall stress (102+/-26 vs 99+/-28 g/cm2), end-systolic (1.7+/-0.3 vs. 1.8+/-0.2) or end-diastolic (1.7+/-0.3 vs. 1.6+/-0.1) sphericity, dp/dt (582+/-163 vs. 678+/-222 mm Hg/s), or right ventricular fractional shortening (20+/-9% vs. 27+/-7%, p = 0.06) in unimproved and improved groups. LV mass was lower (1.00+/-0.21 vs. 1.38+/-0.27 g/ml, p = 0007) and mitral inflow E-wave deceleration time shorter (97+/-42 vs. 164+/-58 ms, p = 0007) in the unimproved versus the improved group. On Pearson correlation analysis, LV mass (r = 0.62, p = 0.001), deceleration time (r = 0.68, p = 0.0002), wall motion score index (r = -0.47, p = 02), and dp/dt (r = 0.52, p = 03) were the significant predictors of LVEF2. There was correlation between LV mass (grams per milliliter) and deceleration time (r = 0.61, p = 0.001). During follow-up, death occurred in 1, and readmission for worsening heart failure in 4 patients in the unimproved group versus no hospitalization in the improved group. Thus, in patients with recent onset IDC, LV mass and diastolic function determine late outcome.

Cardiomyopathy, Dilated↗
PubMed1987

The effects of maternal ambulation on the nonstress test.

Using a recently developed noninvasive telemetry device (model 8240A, Hewlett-Packard Co., Palo Alto, California), we studied, under controlled conditions, the effects of maternal ambulation on the nonstress test patterns of 100 near-term high-risk pregnancies, randomly divided into two equal groups who underwent three alternating 30-minute periods of ambulation and bed rest, beginning either with ambulation (group 1) or bed rest (group 2). Fetal heart rate data were captured and analyzed by a programmed microcomputer for group mean 30-minute fetal heart rate baseline rates and variability and incidences and dimensions of fetal heart rate accelerations and decelerations. Both groups were similar for the maternal and perinatal data examined. The fetal heart rate parameters analyzed were similar within and between each group during each 30-minute testing segment. No episodes of sustained tachycardia or bradycardia were observed. Although 13 fetuses in each group exhibited variable or late decelerations, the incidence of decelerations was no different during periods of rest or ambulation. Maternal ambulation does not elicit abnormal fetal heart rate responses in most high-risk fetuses and may be an acceptable alternative to conventional nonstress test conditions.

Female↗
PubMed1994

Central and peripheral hemodynamic changes in fetuses with absent end-diastolic velocity in umbilical artery: correlation with computerized fetal heart rate pattern.

OBJECTIVES: Our purpose was to study hemodynamic changes in peripheral and central blood vessels and to correlate these changes with the computerized fetal heart rate pattern in fetuses with absent end-diastolic velocity in the umbilical artery. STUDY DESIGN: Doppler studies of the umbilical artery, the middle cerebral artery, and aortic and pulmonic outflow, together with computerized fetal heart rate monitoring, were performed every 2 to 4 days until delivery in 13 fetuses with absent end-diastolic velocity in the umbilical artery. The pulsatility index was calculated from the flow velocity waveforms obtained from the umbilical and middle cerebral arteries. The velocity time integral (an index of cardiac output) and the heart rate were calculated from the flow velocity waveforms obtained from the aortic and pulmonic outflow. RESULTS: Two fetuses were delivered immediately after the first examination because of repetitive fetal heart rate decelerations. One fetus was excluded from the study because of major malformations. Ten had three to eight tests each. Six had a biphasic change of the middle cerebral artery, which consisted of a decrease (p < 0.001) followed by an increase in the pulsatility index (p < 0.05). When the middle cerebral artery lost its vasodilation, there was an increase in the middle cerebral artery/umbilical artery pulsatility index ratio (p < 0.05). Left cardiac output decreased (p < 0.05), resulting in an increase in the pulmonary/aortic velocity time integral x heart rate ratio (p < 0.05). Reduced fetal heart rate variation (< 30 msec) developed in all six fetuses, and they were delivered because of repetitive fetal heart rate decelerations. Four fetuses with only a decrease in the middle cerebral artery pulsatility index did not have reduced fetal heart rate variation or decelerations, the aortic velocity time integral x heart rate didn't decrease, and the pulmonic/aortic velocity time integral x heart rate ratio didn't increase. These fetuses were delivered for reasons other than fetal distress. The middle cerebral artery pulsatility index correlated with the aortic velocity time integral x heart rate (r = -0.53, p < 0.0001), and the middle cerebral artery/umbilical artery pulsatility index correlated with the pulmonic/aortic velocity time integral x heart rate (r = 0.56, p < 0.0001). CONCLUSION: Abnormal fetal heart rate patterns occur in fetuses with absent end-diastolic velocity in the umbilical artery when the middle cerebral artery begins to lose its compensatory maximal dilation. The increase in the middle cerebral artery pulsatility index is associated with a significant reduction in left ventricular output without significant changes in right ventricular function. Thus it appears that a loss of autonomic reactivity occurs in the brain first and is followed within a few days by a similar response in the heart, as shown by the decreased fetal heart rate variation.

Blood Flow Velocity↗
PubMed1997

Fetal heart rate changes do not reflect cardiovascular deterioration during brief repeated umbilical cord occlusions in near-term fetal lambs.

OBJECTIVE: Brief repetitive total umbilical cord occlusions were used to induce fetal asphyxia and to evaluate the interrelationships with hypotension and fetal heart rate decelerations. STUDY DESIGN: In 21 chronically instrumented fetal lambs (gestational age 126.8 +/- 0.6 days), repetitive total umbilical cord occlusion was performed 1 out of 2.5 minutes (n = 7), 2 out of 5 minutes (n = 9), or not at all (shams, n = 5). Occlusions proceeded until fetal blood pressure was < 20 mm Hg or failed to recover to baseline before the next occlusion. RESULTS: At the nadir of asphyxia pH (mean +/- SEM) was 6.84 +/- 0.02, base excess 23.1 +/- 1.0 mmol/L, and lactate 14.2 +/- 0.4 mmol/L. Two fetuses died. The pattern of fetal heart rate decelerations remained relatively consistent throughout the experiments. In contrast, after an initial phase of sustained hypertension a progressive fall in trough blood pressure occurred after approximately 15 minutes of occlusion. The blood pressure recovery time in almost all fetuses lengthened abruptly near the end of the occlusion series, at a variable metabolic threshold. This was accompanied by a significant delay in fetal heart rate recovery in only five fetuses. CONCLUSIONS: Fetal compromise presented with the development of hypotension, without change in the pattern of fetal heart rate response. These data illustrate the limited diagnostic value of fetal heart rate monitoring to identify the development of cardiovascular compromise associated with severe decelerations in the previously healthy fetus.

Animals↗
PubMed2002

Understanding muscle coordination of the human leg with dynamical simulations.

Muscles coordinate multijoint motion by generating forces that cause reaction forces throughout the body. Thus, a muscle can redistribute existing segmental energy by accelerating some segments and decelerating others. In the process, a muscle may also produce or absorb energy, in which case its summed energetic effect on the segments is positive or negative, respectively. This Borelli Lecture shows how dynamical simulations derived from musculoskeletal models reveal muscle-induced segmental energy redistribution and muscle co-functions and synergies. Synergy occurs when co-excited muscles distribute segmental energy differently to execute the motor task. In maximum height jumping, high vertical velocity at lift-off occurs desirably at full body extension because biarticular leg muscles redistribute the energy produced by the uniarticular leg muscles. In pedaling, synergistic ankle plantarflexor force generation during leg extension allows the high energy produced by the uniarticular hip and knee extensors to be delivered to the crank. An analogous less-powerful flexor synergy exists during leg flexion. Hamstrings reduce crank deceleration during the leg extension-to-flexion transition by not only producing energy but delivering it to the crank through its contribution to the tangential (accelerating) crank force, though this hamstrings function occurs at the opposite (flexion-extension) transition when pedaling backwards. In walking, the eccentric quadriceps activity in early stance not only decelerates the leg but also accelerates the trunk. In mid-stance, the uni- and biarticular plantarflexors, by having opposite segmental energetic effects, act in synergy to support the whole body, so segmental potential and kinetic energy exchange can occur. To conclude, the extraction of unmeasurable variables from dynamical simulations emulating task kinematics, kinetics, and EMGs shows how the production of force and energy by individual muscles contribute to the energy flow among the individual segments during task execution.

Bicycling↗
PubMed2003

A comparison of the effects of epidural and meperidine analgesia during labor on fetal heart rate.

OBJECTIVE: To estimate the effects of initiation of epidural analgesia on fetal heart rate (FHR) patterns compared with intravenous meperidine analgesia. METHODS: Fetal heart rate patterns in 200 nulliparous women with term pregnancies randomized to epidural analgesia with 0.25% bupivacaine were compared with those of 156 similar women given intravenous meperidine. Fetal heart rate patterns occurring within 40 minutes of initiation of labor analgesia were retrospectively read by three maternal-fetal medicine specialists who were blind to clinical events, including type of labor analgesia. RESULTS: Meperidine, compared with epidural analgesia, was associated with statistically significantly less beat-to-beat variability (absent or less than 5 beats per minute) of the FHR (30% versus 7% of fetuses, P <.001) in the first 40 minutes after initiation of analgesia, as well as with fewer FHR accelerations (88% versus 62% of fetuses, P <.001). Neither the incidence of FHR decelerations nor the type of deceleration were significantly different between methods of labor analgesia. Specifically, 41% of women given meperidine exhibited FHR decelerations within 40 minutes, compared with 34% given epidural analgesia (P =.353). CONCLUSION: Epidural analgesia does not have deleterious effects on FHR.

Adult↗
PubMed1998

The Jarisch-Herxheimer reaction and fetal monitoring changes in pregnant women treated for syphilis.

OBJECTIVE: To estimate the incidence of the Jarisch-Herxheimer reaction in pregnant women undergoing treatment of syphilis and the incidence of changes in uterine activity or fetal heart rate (FHR). METHODS: Pregnant women of at least 24 weeks' gestation diagnosed as needing treatment of syphilis were reviewed retrospectively. Patients were admitted for their first dose of benzathine penicillin, and the FHR was recorded continuously before and for 24 hours after injection. The occurrence of the Jarisch-Herxheimer reaction was noted, and all available FHR records for this admission were reviewed. Evaluations for changes in the FHR pattern and uterine activity were made. Statistical comparisons used Student t, Fischer exact, and chi2 tests, when applicable (significance P < .05). RESULTS: We reviewed 50 charts and 31 available FHR records. The average gestational age was 30.8 weeks. We found 20 cases of probable Jarisch-Herxheimer reaction (40%). Thirteen of 31 patients (41.9%) developed regular uterine contractions, median onset, 10 hours. All resolved within 24 hours of treatment. Patients with uterine contractions had a greater mean increase in temperature (1.15F versus 0.68F, P < .008). Twelve of 31 women (38.7%) developed recurrent variable decelerations, median onset, 8 hours. All patients but one had their contractions resolve within 24 hours of treatment. Lower gestational age was associated with the occurrence of recurrent variable decelerations (29.6 weeks versus 32.3 weeks, P < .05). No patients required delivery at the time of treatment. CONCLUSION: The incidence of Jarisch-Herxheimer reaction in treated syphilitic pregnancies is about 40%; similar proportions of patients develop regular uterine contractions and recurrent variable decelerations.

Adult↗
PubMed1999

Predictive smooth pursuit eye movements during identification of moving acuity targets.

Repetitive, brief target ramp movements every few seconds lead to anticipatory acceleration before each ramp onset and anticipatory deceleration before ramp offset. We assessed whether identifying novel changes in the pursuit target would alter this pattern of anticipatory pursuit. Without target identification (TI), anticipatory acceleration increased when intervals between ramps were regular, rather than random. It increased further when, between ramps, the target was invisible rather than stationary and visible. Anticipatory deceleration increased when the target was expected to stop rather than disappear at ramp offset. For TI trials, the pursuit target changed briefly into a Landolt C acuity target that had to be identified. Compared to no TI, anticipatory acceleration decreased when a stationary C always appeared just before ramp onset. It increased when a moving C appeared just after ramp onset, but only when the target was invisible between ramps. Anticipatory deceleration was reduced when a moving C appeared just before ramp offset, but did not increase when a stationary C appeared just after ramp offset. The changes were significant, but of small magnitude, suggesting that predictive pursuit, especially with a visible target between ramps, cannot be greatly influenced by attempts to selectively improve acuity at a particular phase of the stimulus.

Adult↗
PubMed2003

Transplantation of mesenchymal stem cells embedded in Atelocollagen gel to the intervertebral disc: a potential therapeutic model for disc degeneration.

Intervertebral disc degeneration is considered to be one of the major causes of low back pain. Despite this irreversible phenomenon, attempts to decelerate disc degeneration using various techniques have been reported. However, to date there has been no proven technique effective for broad clinical application. Based on previous studies, we hypothesize that maintenance of proteoglycan content in the disc is achieved by avoiding the depletion of nucleus pulposus and preserving the structure of the annulus is a primary factor in decelerating disc degeneration. One novel approach to solve the dilemma of intervertebral disc degeneration is found at the stem cell level. Mesenchymal stem cells (MSCs) are known to possess the ability to differentiate into various kinds of cells from mesenchymal origin. Although the majority of cells that contribute to disc formation are known to obtain chondrocyte-like phenotypes, no reported study has emphasized the correlation with mesenchymal stem cells. To evaluate the possible potential of MSCs in disc cell research and treatment of degenerative disc disease, autologous MSCs embedded in Atelocollagen gel were transplanted into the discs of rabbits which had undergone a procedure proven to induce degeneration. The results suggest that MSC transplantation is effective in decelerating disc degeneration in experimental models and provided new hopes for treatment of degenerative disc disease in humans. Atelocollagen gel served as an important carrier of MSCs in transplantation, permitting proliferation, matrix synthesis and differentiation of MSCs. This study strengthens the viable efficacy of practical application of MSCs in treatment of intervertebral disc disease.

Animals↗