Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “The Right to Reproduce”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

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

At least 793 records · Page 44Linked to original sources

The surface variational principle applied to an acoustic cavity.

This paper presents the development and application of the Surface Variational Principle (SVP) for the evaluation of axisymmetric interior acoustic domains. The interior form of the SVP is first developed in the same manner as the existing exterior form. Then, the surface pressure and normal velocity are represented with a Ritz expansion using basis functions that span the entire wetted surface of the object of interest. The resultant formulation is used to analyze the interior acoustic response of a harmonically forced, right circular elastic cylinder. This validation model was chosen as both the structural and acoustic responses can be solved analytically. Results are presented for two models: one with a length to radius ratio of 2.4, and another with a ratio of 12.3. The SVP is shown to well reproduce the analytical solution for this geometry, and displays the asymptotic convergence expected of its variational formulation. The SVP formulation developed here is not restricted to right-circular cylindrical geometries, and may, indeed, be readily applied to any axisymmetric body.

Journal Article↗

Early effects of tetraethylammonium chloride on the contractile properties of isolated rabbit basilar arteries.

The acute vascular effects of tetraethylammonium chloride (TEA) were examined on annular segments of rabbit basilar arteries. Contractions induced by the potassium channel blocker were compared with those obtained for potassium chloride, 5-hydroxytryptamine (5-HT) and norepinephrine (NE). The greater magnitude of the contractions was of the following order: [K+] greater than 5-HT greater than TEA greater than NE. High concentrations of TEA alone (10(-2) M) generated spontaneous oscillatory contractions in cerebral vessels that were normally quiescent. Low concentrations of TEA (10(-8)-10(-6) M), which had no vasomotor properties per se, enhanced the contractile response of submaximal concentrations of 5-HT (10(-7) M) and NE (3 X 10(-6) M) and attenuated the contraction produced by 60 mM [K+]. An increased vascular response to the amines was still evident up to 3 h after the addition of TEA despite frequent rinsing with fresh buffer solutions. On arteries precontracted with TEA (10(-2) M), but not high [K+], the subsequent addition of 5-HT (10(-7) M) still induced a powerful constriction. Repeated concentration-response curves for [K+] were reproducible and, in the presence of TEA (10(-8) or 10(-6) M), the curve was displaced to the right in a competitive manner. A higher concentration of TEA (10(-4) M) was devoid of any blocking properties on the [K+]-induced response whereas, at 10(-3) M TEA, the response was potentiated, as evidenced by a shift of the curve to the left. Interactions between TEA and the cumulative response to 5-HT were difficult to interpret. Repeated exposures of the artery to 5-HT resulted in an increased maximal response with each determination (EAm = 127 +/- 9% and 149 +/- 14% of control values following the second and third applications, respectively). With TEA (10(-6) M), the increase in the maximal contractile effect noted previously was not observed. Contractions induced by single concentrations of TEA (10(-2) M) or [K+] (60 mM) were calcium dependent, were abolished completely in a calcium-free medium, and were depressed by the calcium antagonist nimodipine. 5-Hydroxytryptamine-induced contractions (10(-5) M) were less sensitive to withdrawal of calcium from the extracellular medium (31 +/- 6% relative to the maximal response at 4 mM calcium). Hence, an acute reduction in potassium conductance in cerebrovascular smooth muscle produced by TEA has complex, concentration-dependent effects and reproduces only part of the spectrum of effects of cisternal injection of blood on cerebrovascular reactivity.

Animals↗

Path integration following temporal lobectomy in humans.

Path integration, a component of spatial navigation, is the process used to determine position information on the basis of information about distance and direction travelled derived from self-motion cues. Following on from studies in the animal literature that seem to support the role of the hippocampal formation in path integration, this facility was investigated in humans with focal brain lesions. Thirty-three neurosurgical patients (17 left temporal lobectomy, LTL; 16 right temporal lobectomy, RTL) and 16 controls were tested on a number of blindfolded tasks designed to investigate path integration and on a number of additional control tasks (assessing mental rotation and left-right orientation). In a test of the ability to compute a homing vector, the subjects had to return to the start after being led along a route consisting of two distances and one turn. Patients with RTL only were impaired at estimating the turn required to return to the start. On a second task, route reproduction was tested by requiring the subjects to reproduce a route consisting of two distances and one turn; the RTL group only were also impaired at reproducing the turn, but this impairment did not correlate with the homing vector deficit. There were no group differences on tasks where subjects were required to reproduce a single distance or a single turn. The results indicate that path integration is impaired in RTL patients only and suggest that the right temporal lobe plays a role in idiothetic spatial memory.

Adult↗

Mapping cortical areas associated with Chinese word processing using functional magnetic resonance imaging.

OBJECTIVES: To identify the cortical areas engaged during Chinese word processing using functional magnetic resonance imaging (fMRI) and to examine the reliability and reproducibility of fMRI for localization of functional areas in the human brain. METHODS: FMRI data were collected on 8 young, right-handed, native Chinese speakers during performance of Chinese synonym and homophone judgment tasks on two different clinical MRI systems (1.5 T GE Signa Horizon and 1.5 T Siemens Vision). A cross correlation analysis was used to statistically generate the activation map. RESULTS: Broca's area, Wernicke's area, bilateral extrastriate, and ventral temporal cortex were significantly activated during both the synonym and homophone activities. There was essentially no difference between results acquired on two different MRI systems. CONCLUSIONS: FMRI can be used for localizing cortical areas critical to Chinese language processing in the human brain. The results are reliable and well reproducible across different clinical MRI systems.

Adult↗

Transrectal Doppler sonography of uterine blood flow.

Transrectal Doppler ultrasound was used for the noninvasive investigation of uterine blood flow in cows. Both the left and right Aa. uterinae were scanned to obtain blood flow velocity waveforms over 2 consecutive estrous cycles. Blood flow was reflected by the resistance index (RI) and the time-averaged maximum velocity (TAMV). Intra-observer reproducibility of Doppler measurements was evaluated. The intra-class correlation coefficient (Intra-CC) was 0.97 for the RI and 0.95 for TAMV. While RI values did not differ between the left and right A. uterina (P > 0.05), differences in TAMV occurred between both vessels in 2 cows. These differences were not related to the ovary bearing the dominant follicle or to the corpus luteum (P < 0.001). As in all cows, changes of RI and TAMV values between the left and right artery during the estrous cycle were correlated (correlation coefficient r > 0.72; P < 0.0001); the mean values of both sides were used for subsequent analyses. Variance component estimates for the effect of cow on RI and TAMV were 8 and 13% and for the influence of day of estrous cycle they were 70 and 47%, respectively (P <0.0001). Between estrous cycles no significant differences could be measured within cows (P > 0.05). The highest RI and lowest TAMV values occurred on Day 0 (= day of ovulation) and Day 1, while the lowest RI and highest TAMV values were measured between Days -3 and -1 of the estrous cycle, respectively. There was a positive correlation between TAMV and estrogen concentrations and a negative correlation between RI and plasma estrogen levels. Plasma progesterone levels and TAMV were negatively correlated, but no correlation could be measured (P > 0.05) between RI values and plasma progesterone concentrations. While there were no differences in plasma concentrations of estrogens and progesterone between estrous cycles within cows, the levels of these hormones differed between cows. The results show that transrectal Doppler sonography is a useful, noninvasive method for examining uterine blood flows in cows. If there is an influence of uterine perfusion on fertility in cows its role needs further investigation.

Animals↗

[Transperitoneal laparoscopic right sympathectomy].

Laparoscopic lumbar transperitoneal sympathectomy represents the miniinvasive approach of laterocolic procedure Adson-Diez. It is suitable to laparoscopic surgery, has a good reproducibility and it is more advantageous than total retroperitoneal approach because of a larger working space.

Humans↗

Origin of chronic right upper quadrant pain.

We have studied 22 consecutive patients referred for investigation of severe chronic right upper quadrant pain. The majority were women whose symptoms had been present for many years. All had undergone repeated investigations of the pancreatico-biliary, gastro-intestinal, urinary, and even gynaecological systems without a satisfactory diagnosis. Most had undergone at least one abdominal operation in an unsuccessful attempt to cure their pain. In 21 of 22 patients the customary pain was completely and reproducibly mimicked by balloon distension of the small or large intestine in at least one site. The trigger sites were jejunum (15), ileum (12), right colon (nine), and duodenum (six). In 12 more than one trigger site was found. Close questioning revealed features of the irritable bowel syndrome in the majority and depression in many though the symptoms were not spontaneously volunteered. Reproduction of pain has provided a convincing demonstration to this difficult group of patients that they have a sensitive gut and allows appropriate management.

Abdomen↗

Muscle contraction-induced steal model in the anesthetized cat.

The current study describes a model in the anesthetized cat which may be used to investigate pharmacological interventions for the treatment of vascular "steal" during muscle contraction. An artificial stenosis was placed around both the descending abdominal aorta and the left external iliac artery. Arterial blood flow was measured in the right and left external iliac and right femoral arteries. Contraction of the left hindquarters, induced by electrical stimulation of the left sciatic and femoral nerves, resulted in an increase of left iliac artery blood flow from 14.7+/-2.0 to 30.5+/-2.8 ml min-1 (p<0.001). A simultaneous reduction of blood flow measured at the level of the right femoral artery (6.7+/-0.1 to 4.5+/-0.7 ml min(-1), p<0.01) was observed in the noncontracting hindlimb (y = 7.76 - 0.10x, correlation coefficient = -0.865). The magnitude of each response was reproducible within the same animal. Administration of 8-phenyltheophylline, a nonselective antagonist of adenosine receptors, reduced the functional hyperemia response within the left external iliac artery by 32% and reduced the "steal" from the vascular bed perfused by the right femoral artery by 21%.

Anesthesia↗

[Assessment of right atrial and ventricular function by radionuclide ventriculography using continuous infusion of 81mKr].

The purpose of this study is to assess the right atrial and ventricular function by radionuclide ventriculography using continuous infusion of 81mKr in normal subjects and in patients with heart disease. 1) Reproducibility of RVEF measurement by continuous infusion of 81mKr was good (interobserver; gamma = 0.97, p less than 0.001, n = 20: intraobserver; gamma = 0.97, p less than 0.001, n = 20). This method had a excellent correlation with RVEF of 99mTc first-pass technique (gamma = 0.92, p less than 0.001, n = 20). 2) RVEF was measured in 10 normal volunteers, 76 patients with myocardial infarction (OMI), 20 patients with dilated cardiomyopathy (DCM), 5 patients with arrhythmogenic right ventricular dysplasia (ARVD) and 5 patients with primary pulmonary hypertension (PPH). In OMI and DCM, their RVEF was lower than that of normal volunteers and, in ARVD and PPH, lower than that of OMI and DCM. There was a significant inverse correlation between RVEF, mean pulmonary artery pressure and right ventricular end-diastolic volume index. 3) The effect of the location of right coronary artery (RCA) lesions on RVEF during exercise was also evaluated. Ten normal volunteers and 27 patients with OMI were studied at rest and during exercise. The patients with OMI were divided into two groups: those without proximal RCA lesions (non RCA group, n = 12) and those with proximal RCA lesions (RCA group, n = 15). Although there were no significant increases of RVEF during exercise in both group, the percent change in RVEF was less in RCA group than in non RCA group. These findings suggested that proximal RCA stenosis is a major determinant of exercise RVEF. 4) To assess the right atrial function, right atrial volume curve was measured in 10 normal volunteers, 32 patients with OMI and 4 patients with PPH. The curve was clearly divided into 4 phase; filling phase (312 +/- 40 msec), early ejection phase (276 +/- 53 msec), plateau an index of right atrial reservoir function, was 0.41 +/- 0.05 and Contractile Volume/Stroke Volume (Contr. V/SV), as an index of right atrial pump function, was 0.23 +/- 0.05 in normal volunteers. In OMI and PPH, atrial reservoir function decreased and atrial pump function increased. It was concluded that radionuclide ventriculography using continuous infusion of 81mKr was useful to assess the right heart function.

Atrial Function, Right↗

Reproducibility of cerebral oxygenation measurement in neonates and infants in the clinical setting using the NIRO 300 oximeter.

OBJECTIVE: To study reproducibility of cerebral tissue oxygenation index (cTOI) values in neonates and infants in a clinical setting using the NIRO 300 oximeter (Hamamatsu Photonics, Hamamatsu City, Japan). DESIGN: Clinical, observational study. SETTING: University hospital, pediatric intensive care unit. PATIENTS: Twenty neonatal and pediatric intensive care patients (age 0-190 days; median 4.5 days). INTERVENTIONS: Reproducibility of cTOI was measured at the lateral forehead of the patients. MEASUREMENTS AND MAIN RESULTS: Sensor exchange experiments were performed by removing the sensor and reapplying another sensor (sensor 1 vs. sensor 2) at the same position. Simultaneous measurements, comparing cTOI values from the right and left forehead, were performed using both sensors. Corresponding sensor exchange experiments were performed within 10 mins. All tests were done under stable, steady-state cardiorespiratory conditions. Data were compared using Bland-Altman bias analysis and paired, two-sided Student's t-test (p < .05). Sensor exchange experiments and simultaneous left-to-right forehead measurements revealed only small mean differences (<5%) and no significant differences between corresponding values (p = .953/.164). However, Bland-Altman bias analysis revealed poor agreement with large 95% limits of agreement in particular for sensor exchange experiments (-17.8% to 17.6%) and less for simultaneous left and right measurements (-14.4% to 10.4%). CONCLUSIONS: The present study shows that cTOI measurements using the NIRO 300 oximeter at the lateral forehead of neonates and infants are not well reproducible under clinical conditions. This raises the question whether generally valid normal values can be defined with the used approach and makes it difficult to determine a normal range of cerebral oxygenation.

Brain↗

Distinct mouse coronary anatomy and myocardial infarction consequent to ligation.

UNLABELLED: This study describes the coronary anatomy of C57BL/6 mice and the functional impact of that anatomy on myocardial infarctions induced by ligation of the left coronary artery. In contrast to humans, a distinct septal coronary artery was observed in all mice arising either from a separate ostium from the right sinus of Valsalva or as a branch of the right coronary artery. Ligation of the left coronary artery at the site of its emergence from under the left atrium resulted in reproducible large myocardial infarctions involving the anterolateral, posterior, and apical regions of the heart as evidenced by histology and echocardiography. Interestingly, the septum was spared from infarction as predicted by the presence of the distinct septal branch found in mice. Thus, the distinct mouse coronary artery anatomy results in different regionality of infarction compared with man and large laboratory animals, and this may affect on the associated pathological remodeling of the heart. BACKGROUND: The objective of this study was to describe the coronary anatomy of C57BL/6 mice and determine the functional impact of that anatomy on myocardial infarctions induced by ligation of the left coronary artery. METHODS: C57BL/6 mice were used to visualize mouse coronary anatomy and to generate myocardial infarction. Mouse coronary artery visualization was performed on isolated hearts using injection of Silastic sealant into the aortic arch. After left thoracotomy myocardial infarction was produced by ligating the left coronary artery at the site of the vessels' emergence past the tip of the left atrium. Echocardiography was performed to analyze heart function, and histology was performed to delineate myocardial infarction. RESULTS: The different septal coronary artery was observed in all mice arising either from a separate ostium from the right sinus of Valsalva or as a branch of the right coronary artery. The mouse left coronary artery passed obliquely across the left ventricular free wall similar to the ramus intermedius coronary artery variant in man. Ligation of the left coronary artery as it emerged from under the left atrium resulted in reproducible large infarctions involving the anterolateral, posterior, and apical regions of the heart as demonstrated by histology and echocardiography. Notably, the septum was spared from infarction as predicted by the presence of the distinct septal coronary artery found in mice. CONCLUSIONS: Mouse coronary anatomy is distinct compared to man or large laboratory animals, and myocardial infarctions resulting from ligation of the mouse left coronary artery spare the septum, which may affect the pathological remodeling of the heart.

Animals↗

Reproducibility of measurements of intima-media thickness and distensibility in the common carotid artery.

OBJECTIVE: To assess reproducibility of ultrasonographic measurements of arterial distensibility and intima-media thickness (IMT) in the common carotid arteries. DESIGN: Prospective study. MATERIALS: Measurements of IMT and arterial distensibility were performed on-line in B-mode and M-mode, respectively. Blood pressure was assessed. From the measured variables stiffness indices were derived. METHODS: Twenty-five persons were included in the IMT study, both healthy subjects and patients with atherosclerotic disease. Distensibility was measured in a randomly selected subgroup of 10 persons. All subjects were examined by two different sonographers on the same day and were re-examined after 1 or 2 weeks. RESULTS: When data from both carotid arteries were combined, the interobserver coefficient of variation of IMT was on average 11.7%, of diastolic diameter 3.3% of distension and relative distension 11.8%, of distensibility coefficient 12.3%, and of stiffness parameter beta 19%. Intraobserver variability was slightly lower than interobserver variability. Variability for measurements in the right common carotid artery only was higher than for measurements of both carotid arteries combined. CONCLUSIONS: Our study demonstrates that reproducibility of measurements of IMT and arterial distensibility of the common carotid artery, by B-mode and M-mode ultrasonography respectively, is acceptable when used in large studies.

Aged↗

Sequential magnetic resonance monitoring of pulmonary flow with endovascular stents placed across the pulmonary valve in growing Swine.

BACKGROUND: Patients with endovascular stent implantation for the treatment of right ventricular outflow tract obstruction are often left with incomplete relief of the obstruction and significant pulmonary regurgitation. A noninvasive and reproducible method for monitoring such patients is desirable. MRI in the presence of a stent, however, has to overcome the problem of potential metallic artifacts. METHODS AND RESULTS: Under x-ray fluoroscopic guidance, endovascular nitinol stents were placed across the pulmonary valve in 6 young pigs to induce pulmonary regurgitation. Five additional pigs served as controls. Initial MRI was performed after 2 days (13.5+/-1.8 kg) and follow-up after 3 months (32+/-2.9 kg). Pulmonary flow volumes and regurgitant fraction were quantified by velocity-encoded cine (VEC) MRI through (VEC-TS) and distal to (VEC-DS) the stent. VEC-TS was compared with VEC-DS and volumetric measurements of left and right ventricular stroke volumes provided by cine MRI ("gold standard"). Antegrade and retrograde pulmonary flow volumes by VEC-TS were slightly but significantly less than those with VEC-DS and cine MRI. Excellent correlations (r>0.97) for phasic pulmonary flow volumes as measured by VEC-TS and VEC-DS were shown. Pulmonary regurgitant fraction increased from 32.8+/-15% to 49.6+/-17% (P<0.05) over the course of 3 months with VEC-TS. CONCLUSIONS: MRI demonstrates the progression of pulmonary regurgitation in growing swine. VEC MRI has the ability to quantify pulmonary blood flow inside the lumen of nitinol stents. MRI appears to be ideally suited for monitoring patients with endovascular nitinol stents in the pulmonary artery or pulmonary valve position.

Alloys↗

Comparison of fixed-flexion positioning with fluoroscopic semi-flexed positioning for quantifying radiographic joint-space width in the knee: test-retest reproducibility.

OBJECTIVE: To compare fixed-flexion radiography of the knee with fluoroscopic semi-flexed radiography in terms of the reproducibility of measurements of minimum joint-space width (JSW) in the medial femorotibial joint. METHODS: Posteroanterior radiographs of the right knees of 18 normal volunteers were acquired with the patients standing on an upright fluoroscopy table, the feet externally rotated 10 degrees and the toes touching the vertical table. Knees were positioned and radiographed with two different techniques: (1) semi-flexed positioning under fluoroscopic guidance using a horizontal X-ray beam; and (2) fixed-flexion positioning, with the knees and thighs touching the vertical table, using 10 degrees caudal beam angulation without fluoroscopy. Foot maps were drawn in each case. Subjects were repositioned and radiographed twice using each technique. The posteroanterior beam angle that optimally projected the medial tibia plateau with the patient in the fixed-flexion position was also determined for each subject in a separate examination using fluoroscopy. Ten patients with osteoarthritis were also examined with the fixed-flexion technique using a conventional radiographic unit. Minimum medial joint-space width (JSW) in the medial femorotibial joint was measured manually with a graduated lens and also with a semi-automated computer algorithm. RESULTS: Reproducibility errors (root-mean-square SD) for manual and automated JSW measurement were 0.2 mm and 0.1 mm, respectively, for fluoroscopic semi-flexed positioning in volunteers; 0.3 mm and 0.1 mm, respectively, for fixed-flexion positioning in volunteers; and 0.2 mm and 0.1 mm, respectively, for fixed-flexion positioning in osteoarthritic patients. The optimal beam angle for visualizing the joint space was 9.0 degrees +/-3.6 degrees. CONCLUSION: Fixed-flexion, non-fluoroscopic radiography of the knee can provide reproducible JSW measurement using widely available X-ray equipment. This technique is more feasible for multicenter clinical studies and routine clinical use than are methods that rely on fluoroscopic alignment of the tibial plateau.

Adult↗

Right ventricular diastolic filling: evaluation with velocity-encoded cine MRI.

Abnormal flow velocity curves across the tricuspid valve (TV) and in the superior vena cava have been described in patients with abnormal right ventricular (RV) relaxation or restriction and with pericardial diseases by means of Doppler echocardiography. In this study, various imaging planes and strategies of velocity-encoded cine (VEC) MR for measurement of peak E and peak A velocities and the E/A ratio across the TV were evaluated and compared to Doppler measurements in 10 normal volunteers. In addition, VEC-MR velocity measurements were performed in the superior vena cava. Peak E and peak A velocities derived from three-dimensional VEC-MR phase images were slightly higher than velocities derived from two-dimensional VEC images. Higher velocities were measured by VEC-MR in the vertical long-axis plane compared with the horizontal long-axis plane. Excellent correlations (r > 0.89) were found between E/A ratios derived by VEC-MR and Doppler echocardiography. The interobserver variability for VEC-MR measurements was in the range of 2%. The VEC-MR depicted normal superior vena cava velocity curves in every volunteer. These results indicate that VEC-MR may offer a highly reproducible means of assessing abnormal filling properties of the RV.

Adult↗

Chronic anterior pallidal stimulation for Parkinson's disease.

We present the case of a 51-year-old female who had a four-year history of Parkinson's disease with severe "on-off' and disabling progression of symptoms on chronic levodopa therapy. After obtaining FDA approval, we implanted a Medtronic deep brain stimulation lead stereotactically into the right anterior pallidum contralateral to her most symptomatologic side. Intra-operative stimulation trials at 100 Hz caused reproducible reversal of akinetic symptoms and simultaneous microelectrode recording of the posteroventral pallidum revealed decreased neural activity during anterior pallidal stimulation. The patient was evaluated pre-operatively and postoperatively using the Hoehn and Yahr Staging Scale, the Unified Parkinson's Disease Rating Scale (UPDRS), videotape, and a computerized data glove. Six months after implantation, the total UPDRS score was decreased from 68 to 8 and Hoehn and Yahr Staging improved from 3.0 to 1.5 during periods of chronic high frequency stimulation. Dramatic improvements in tremor, dystonia, bradykinesia, and akinesia were noted within seconds of stimulator activation and were also objectively measured using a computerized data glove. This case reveals the potential for therapeutic pallidal stimulation for Parkinson's akinetic symptomatology.

Antiparkinson Agents↗

The reproducibility of left ventricular volume and mass measurements: a comparison between dual-inversion-recovery black-blood sequence and SSFP.

The aim of this study was to compare a dual-inversion-recovery black-blood (BB) magnetic resonance imaging (MRI) sequence with steady-state free precession (SSFP) for the assessment of left ventricular parameters. The improved endocardial border definition seen with SSFP was not observed at the epicardial border. Improvements in segmentation at the left ventricular epicardial border have been observed with this black-blood sequence. Left ventricular (LV) mass and LV end-diastolic volume (EDV) measurements as well as inter-observer and intra-observer variability were compared between images acquired with a dual inversion BB and SSFP sequence. The mean+/-1 standard deviation (SD) for LV EDV was 178.3+/-52.7 ml measured with SSFP and 158.8+/-62.2 ml with BB. This difference was not statistically significant (p=0.22). For SSFP, the mean value of LV mass was 124.0+/-27.0 g and 147.5+/-37.4 g for BB, a statistically significant difference (p<0.0001). The dual-inversion-recovery BB imaging showed improved reproducibility for LV mass measurements compared with SSFP and improved spatial resolution. For studies requiring LV mass measurements, the dual-inversion-recovery BB sequence offers improved spatial resolution and improved reproducibility to SSFP.

Adult↗