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At least 91 records · Page 5Linked to original sources
PubMed2005

Three-dimensional rotational angiography of transplanted renal arteries: influence of an extended angle of rotation on beam-hardening artifacts.

PURPOSE: To investigate whether three-dimensional rotational angiography (3D-RA) of the transplant renal artery performed with an extended angle of rotation can reduce beam-hardening artifacts in 3D reconstructed images without image quality being lost or side effects to the transplanted kidney being increased. MATERIAL AND METHODS: 3D-RA with a C-arm rotation of 180 degrees was performed consecutively in 12 renal transplanted patients with suspicion of renal artery stenosis. A 1.7-mm balloon occlusion catheter was placed using the crossover technique and this was compared to a protocol with 160 degrees rotation and a traditional 1.4-mm catheter in 10 patients. The occurrence of beam-hardening artifacts was registered and the effects of the reduced contrast load on image quality and of arterial occlusion on renal function were assessed. RESULTS: The extended angle of rotation, from 160 degrees to 180 degrees, reduced the beam-hardening artifacts. Artifacts were observed in 4/11 patients (36%) in the study group and in all 10 (100%) of the controls. There was no statistical difference regarding image quality between the two protocols. Renal function was equally affected in both protocols. CONCLUSION: 3D-RA with an extended C-arm rotation reduced the beam-hardening artifacts. Image quality was not reduced despite the reduced contrast medium load. The different protocols had no effect on patient outcome.

Adult↗
PubMed2000

Perforation of rotator cuff increases interleukin 1beta production in the synovium of glenohumeral joint in rotator cuff diseases.

OBJECTIVE: To study the hypothesis that perforation of the rotator cuff increases the degree of inflammation in the synovium of the glenohumeral joint in rotator cuff diseases. METHODS: Thirty-five synovial specimens in the glenohumeral joint of patients with rotator cuff diseases were examined. They were obtained during surgery and divided into 2 groups on the basis of the presence or absence of rotator cuff perforation, i.e., perforating and nonperforating tears. The expression levels of inflammatory cytokine mRNA of interleukin 1beta (IL-1beta) and 2 forms (secreted type and intracellular type) of IL-1 receptor antagonist (IL-1ra) were measured by reverse transcriptase polymerase chain reaction (RT-PCR). The protein level of IL-1beta was determined by Western blot analysis. IL-1beta producing cells were also identified by in situ RT-PCR and immunohistochemistry. RESULTS: In perforating tears cytokine mRNA in the glenohumeral synovium was more significantly expressed than in nonperforating tears. Also, higher levels of IL-1beta protein were detected in perforating tears. CONCLUSION: Perforation of the rotator cuff increases IL-1beta production in the glenohumeral joint, enhancing inflammatory intensity at the site. These findings suggest the possibility that glenohumeral synovitis in rotator cuff diseases may be a factor for the development of glenohumeral arthropathy.

Adult↗
PubMed2000

Hyperfine Structure in the Rotational Spectrum of GaF: A Comparison of Experimental and Calculated Spin-Rotation and Electric Field Gradient Tensors.

The high-resolution pure rotational spectrum of GaF has been measured using a Balle-Flygare-type Fourier transform spectrometer. Improved nuclear quadrupolar coupling constants and rotational constants have been obtained along with the first reported fluorine spin-rotation constant for gallium fluoride, C(I) ((69)Ga(19)F, v = 0) = +32.0(21) kHz. Accurate spin-rotation tensors from microwave or molecular beam spectroscopy are particularly important to NMR spectroscopists and theoreticians because these data provide information about anisotropic nuclear magnetic shielding in the absence of intermolecular effects. For quadrupolar nuclei such as gallium, the quadrupolar interaction is sufficiently large that it is very difficult to characterize shielding tensors directly via NMR spectroscopy. The experimentally determined nuclear quadrupolar coupling constants and spin-rotation constants for GaF are compared with the results of a series of high-level ab initio calculations carried out at various levels of theory with a range of basis sets. Further calculations on BF and AlF, supplemented with available experimental data for InF and TlF, allow for the investigation of trends in nuclear magnetic shielding, spin-rotation, and electric field gradient tensors in the group-13 fluorides. Calculations at the MP2/6-311++G** and MP2/6-311G(2df, 2pd) levels provide the most consistently satisfactory results in comparison with the experimental data. Copyright 2000 Academic Press.

Journal Article↗
PubMed1988

The effects of gravitoinertial force level and head movements on post-rotational nystagmus and illusory after-rotation.

The effect of Coriolis, cross-coupled stimulation on the vestibuloocular reflex and the elicitation of motion sickness depends on background gravitoinertial force level (DiZio et al. 1986, 1987; Graybiel et al. 1977; Lackner and Graybiel 1984, 1986). We have explored whether this response dependency is related to the unusual patterns of sensorimotor activity present during exposure to non-terrestrial gravitoinertial force levels, to alterations in the encoding of head movements in different gravitoinertial force environments, or to some combination thereof. Blindfolded subjects were exposed to sudden stops after constant velocity, vertical z-axis rotation, sometimes with and sometimes without post-rotational head movements, in the 0 G, 1 G, and 1.8 G force phases of parabolic flight. After sudden stops without head movements, the time constant of decay of post-rotational nystagmus was significantly lower in 0 G than in 1 G and lower to a smaller extent in 1.8 G. Post-rotational head movements decreased the decay time constants in 1 G and in 1.8 G, but not in free fall. The same pattern emerged for the duration of illusory after-rotation. Systematic changes were not found in the peak slow phase velocity of nystagmus. These results suggest that tonic levels of otolithic and somatosensory activity in combination with canalicular, cervical, and motor activity regulate the velocity storage mechanism of the horizontal vestibuloocular reflex (Cohen et al. 1977; Raphan et al. 1979) and sensations of after-rotation. These same factors are likely to be important etiological elements in space motion sickness.

Coriolis Force↗
PubMedDate not supplied

Wear of fixed bearing and rotating platform mobile bearing knees subjected to high levels of internal and external tibial rotation.

In order to extend the lifetime of total knee replacements (TKR) in vivo, reduction of the volumetric wear rate of ultra high molecular weight polyethylene (UHMWPE) bearings remains an important goal. The volume of wear debris generated in fixed bearing total knee devices increases significantly when subjected to higher levels of internal-external rotation and anterior-posterior displacement. Six PFC Sigma fixed bearing TKR were compared with six LCS rotating platform mobile bearing knees using a physiological knee simulator with high rotation kinematic inputs. The rotating platform polyethylene inserts exhibited a mean wear rate which was one-third of that of the fixed bearing inserts despite having increased femoral contact areas and additional tibial wear surfaces. The rotating platform design decouples knee motions, by allowing unidirectional motion at the tray-insert articulation, which reduces rotation at the femoral-insert counterface. This translation of complex knee motions into more unidirectional motions results in molecular orientation of the UHMWPE and reduced volumetric wear.

Journal Article↗
PubMed2004

Combined pre- and retrosigmoid approach for petroclival meningiomas with the aid of a rotatable head frame: peri-auricular three-quarter twist-rotation approach: technical note.

We used the combined subtemporal presigmoid and suboccipital retrosigmoid multidirectional approach with the aid of a rotatable head frame (periauricular three-quarter twist-rotation approach) in 20 cases of petroclival meningiomas. Patients were placed in the lateral decubitus (park-bench) position. The head is twisted, rotated, and positioned 30 degrees face down in the Sugita rotatable head frame. By rotating this head frame, a 30- to 60-degree face-down position can be obtained when the suboccipital retrosigmoid route is used. Alternatively, the straight lateral or slightly brow-up position is obtained when the subtemporal presigmoid route is used. This twist-rotation approach provides multiple trajectories through the petroclival region with minimal drilling of the petrous bone, fatigue of the surgeon, and retraction of the brain.

Journal Article↗
PubMed1999

Involuntary Rotations of a Steering Device Induced by Voluntary Rotations of the Head and Maintained Eccentric Head Positions.

In a series of 4 experiments, the authors examined involuntary rotations of a steering device (handlebar or wheel) that were associated with periodic head rotations and eccentric head positions. Periodic head rotations resulted in isodirectional involuntary rotations of a horizontally arranged steering device of very small amplitude. When the orientation of a steering wheel was changed to vertical and to a backward tilt, the involuntary rotations were in the opposite direction. That pattern of results is consistent with the assumption that small movements of the shoulder girdle, which are associated with head turns and which cannot be prevented by mechanical immobilization of the shoulder, are propagated to the wheel, but is not consistent with previous suggestions that involuntary rotations of a steering device can result from the action of the tonic neck reflex. Effects that correspond to the pattern of the tonic neck reflex were found only when a spring-centered handlebar was held in an eccentric position; maintenance of the eccentric position was facilitated when the participant's head was turned in the opposite direction. The findings strongly suggest that head movements can result in involuntary movements of a steering device via different mechanisms.

Journal Article↗
PubMed1987

Periodic rotational crosses. III. Sire-breed rotations with overlapping generations among dams.

Sire-breed rotations are defined as the changing of sire breeds ignoring the sire-breed pedigree of dams from overlapping generations. The limiting theoretical proportion of maximum potential heterozygosity maintained at equilibrium when there is no culling of dams was found to be equal to that of a composite population with the same breed composition. Heterozygosity was simulated with a deterministic model that assumed 20% of reproducing females in each age group were culled each mating period. Maximum age of reproducing females was varied from 3 to 10 mating periods (years for cattle and sheep, half-years for swine). Consecutive use of each sire breed in a sire-breed sequence from two to four mating periods maintained more heterozygosity than predicted by the limiting theoretical formula, which did not take the culling of females into account. Compared with complete sire and dam rotations, sire-breed rotations with the same breed sequence resulted in reductions of .03 to .13 of potential heterosis. Among two-breed, periodic rotations, the difference ranged from .03 to .08. The smaller differences were generally associated with younger maximum reproducing females ages and the larger differences with older maximum ages. Heterozygosity difference times heterosis is a measure of the expected returns for the more intensive management often needed for complete rotations. Scaled breed difference ranges over which one periodic rotation of sire breeds exceeds another are shifted by overlapping generations among the females. Breed utilization is unchanged by overlapping generations, but relative differences in heterosis utilization are altered.

Animal Husbandry↗
PubMed2003

Double-row arthroscopic rotator cuff repair: re-establishing the footprint of the rotator cuff.

Recently, there has been an increased interest in the normal anatomy of the rotator cuff footprint and the re-establishment of the footprint during rotator cuff repair. Single-row suture anchor techniques have been criticized because of their inability to restore the normal medial-to-lateral width of the rotator cuff footprint. In this report, the authors describe a double-row technique for rotator cuff repair that re-establishes the normal rotator cuff footprint, increases the contact area for healing, and may potentially improve clinical results.

Arthroscopy↗
PubMed2006

Arthroscopic insertion of a biologic rotator cuff tissue augmentation after rotator cuff repair.

Tissue augmentation has been used to reinforce repairs of massive chronic rotator cuff tears. This report describes a new technique for arthroscopic insertion of a biologic rotator cuff tissue augmentation. Double-loaded suture anchors are needed for the technique. One suture is used for the rotator cuff repair and 1 suture is used for the tissue augmentation. The sutures for the tissue augmentation are left exiting through accessory portals. Two free sutures are then passed through the repaired rotator cuff, 1 anteromedially and 1 posteromedially via the anterior and posterior cannulae, respectively. One limb from each of these 4 sutures is retrieved through the lateral portal. Each of the 4 limbs exiting through the lateral portal are then passed through the corresponding corner of the tissue augmentation and Mulberry knots are tied in each suture limb, on top of the tissue augmentation. The suture limbs of the 4 sutures exiting through the anterior and posterior cannulae and accessory portals are pulled simultaneously to reduce the tissue augmentation down onto the repaired rotator cuff. A trocar is used to help push the tissue augmentation through the lateral cannula. The Mulberry knots from each of the sutures are sequentially retrieved and tied arthroscopically to secure the tissue augmentation.

Arthroscopy↗
PubMed2006

Acute rotator cuff tear: do we miss the early diagnosis? A prospective study showing a high incidence of rotator cuff tears after shoulder trauma.

The aim of this study was to evaluate the epidemiologic data of patients with an acute soft-tissue injury to the shoulder, with an emphasis on improving the early diagnosis of acute rotator cuff tears. This study included 104 patients, with a median age of 49 years (range, 19-75 years). The patients were evaluated clinically and with ultrasonography at a median of 13 days (range, 3-49 days) after the injury. A total of 60 patients (58%) had some degree of cuff lesion on the ultrasonographic examination. Of these patients, 33 (32%) had a full-thickness rotator cuff tear, 14 (13%) had a partial-thickness cuff tear in the tendon substance, and 13 (13%) had a partial cuff tear at the insertion site on the major tubercle. The injury mechanism or activity at the moment of injury did not correlate with the presence of a rotator cuff lesion, but we found a strong age correlation, with a prevalence of any rotator cuff tear, above 50%, for patients aged above 50 years and with a prevalence of full-thickness tears of 50% in the groups aged 50 to 59 years and aged 60 to 69 years. In conclusion, this study found a high incidence of rotator cuff lesions by further evaluation of patients undergoing consultation at the emergency department, with an inability to perform active abduction above 90 degrees and normal radiographs, after an acute shoulder trauma.

Adult↗
PubMed2006

[Arthroscopic rotator cuff repair for the treatment of rotator cuff tear].

OBJECTIVE: To discuss and evaluate the surgical techniques of arthroscopic rotator cuff repair and its clinical results. METHODS: From March 2002 to May 2005, 44 out of 68 patients treated by arthroscopic rotator cuff repair had been reviewed with a mean post-operation time of 12 months. Of the 44 patients, 40 were available for follow-up, with a mean period of 20.6 (12 - 40) months. The mean age was 56 (30 - 81) years. According to Gerber classification, there were 8 partial tears, 27 small tears and 5 massive tears. No irreparable tear was included in this series. All tears were repaired under the scope, and metal suture anchor (Super-Revo, Linvatec) had been used in all patients. ASES score (American shoulder & elbow surgeons' score), Constant-Murley score and SST (simple shoulder test) questionnaire were adopted before operation and at the latest follow-up. RESULTS: The pre-operation and post-operation mean ASES score was 72.6 vs. 92.3 (P < 0.001), with the mean VAS score for pain 6.2 vs. 1.8 (P < 0.001), the mean forward flexion 74.5 degrees vs. 146.0 degrees (P < 0.001), and the mean external rotation 27.8 degrees vs. 38.3 degrees (P < 0.01). The excellent and good rate for post-operation ASES was 92.5%. The pre-operation and post-operation mean Constant-Murley score was 69.6 vs. 90.4 (P < 0.001), with an excellent and good rate of 90.0%. CONCLUSIONS: Arthroscopic rotator cuff repair is a successful treatment for rotator cuff tear. By the use of suture anchors, scope surgery shares the advantages of minimal morbidity, quick functional recovery and protection of deltoid muscle. With appropriate indication control, descent surgical skill and intense postoperative rehab, gratifying outcome can usually be anticipated.

Adult↗
PubMed2000

Observations of rotation within the F(o)F(1)-ATP synthase: deciding between rotation of the F(o)c subunit ring and artifact.

F(o)F(1)-ATP synthase mediates coupling of proton flow in F(o) and ATP synthesis/hydrolysis in F(1) through rotation of central rotor subunits. A ring structure of F(o)c subunits is widely believed to be a part of the rotor. Using an attached actin filament as a probe, we have observed the rotation of the F(o)c subunit ring in detergent-solubilized F(o)F(1)-ATP synthase purified from Escherichia coli. Similar studies have been performed and reported recently [Sambongi et al. (1999) Science 286, 1722-1724]. However, in our hands this rotation has been observed only for the preparations which show poor sensitivity to dicyclohexylcarbodiimde, an F(o) inhibitor. We have found that detergents which adequately disperse the enzyme for the rotation assay also tend to transform F(o)F(1)-ATP synthase into an F(o) inhibitor-insensitive state in which F(1) can hydrolyze ATP regardless of the state of the F(o). Our results raise the important issue of whether rotation of the F(o)c ring in isolated F(o)F(1)-ATP synthase can be demonstrated unequivocally with the approach adopted here and also used by Sambongi et al.

Actins↗
PubMed1999

A new method for estimating the axis of rotation and the center of rotation.

A new method is presented for estimating the parameters of two different models of a joint. The two models are: (1) A rotational joint with a fixed axis of rotation, also referred to as a hinge joint and (2) a ball and socket model, corresponding to a spherical joint. Given the motion of a set of markers, it is shown how the parameters can be estimated, utilizing the whole data set. The parameters are estimated from motion data by minimizing two objective functions. The method does not assume a rigid body motion, but only that each marker rotates around the same fixed axis of rotation or center of rotation. Simulation results indicate that in situations where the rigid body assumption is valid and when measurement noise is present, the proposed method is inferior to methods that utilize the rigid body assumption. However, when there are large skin movement artefacts, simulation results show the proposed method to be more robust.

Artifacts↗
PubMed1976

Mental rotation by the blind: does mental rotation depend on visual imagery?

Congentially blind adventitiously blind, and blindfolded sighted adults made same-different judgments of pairs of tactile forms. Two forms were presented in the same orientation, or one form differed from the other by a clockwise rotation of 30 degrees, 60 degrees, 120 degrees, or 150 degrees. Like the reaction times for the sighted and the adventitiously blind, reaction times for the congenitally blind increased as a linear function of angular discrepancy between stimuli, suggesting that the congentially blind, like the sighted and adventitiously blind, mentally rotated one form into congruence with the other to make judging easier. Corroboration of the mental rotation inference came from subjects' introspective reports. Inasmuch as the congenitally blind presumably do not have the ability to visually represent form, the present results suggest that mental rotation does not depend upon visual imagery. Thus, with respect to current speculation as to whether visual imagery is a necessary component of mental rotation, the present findings suggest that it is not.

Adolescent↗
PubMed2003

Catalysis and rotation of F1 motor: cleavage of ATP at the catalytic site occurs in 1 ms before 40 degree substep rotation.

F1, a water-soluble portion of FoF1-ATP synthase, is an ATP hydrolysis-driven rotary motor. The central gamma-subunit rotates in the alpha 3 beta 3 cylinder by repeating the following four stages of rotation: ATP-binding dwell, rapid 80 degrees substep rotation, interim dwell, and rapid 40 degrees substep rotation. At least two 1-ms catalytic events occur in the interim dwell, but it is still unclear which steps in the ATPase cycle, except for ATP binding, correspond to these events. To discover which steps, we analyzed rotations of F1 subcomplex (alpha 3 beta 3 gamma) from thermophilic Bacillus PS3 under conditions where cleavage of ATP at the catalytic site is decelerated: hydrolysis of ATP by the catalytic-site mutant F1 and hydrolysis of a slowly hydrolyzable substrate ATP gamma S (adenosine 5'-[gamma-thio]triphosphate) by wild-type F1. In both cases, interim dwells were extended as expected from bulk phase kinetics, confirming that cleavage of ATP takes place during the interim dwell. Furthermore, the results of ATP gamma S hydrolysis by the mutant F1 ensure that cleavage of ATP most likely corresponds to one of the two 1-ms events and not some other faster undetected event. Thus, cleavage of ATP on F1 occurs in 1 ms during the interim dwell, and we call this interim dwell catalytic dwell.

Adenosine Triphosphate↗
PubMed1992

Role of the capsulo-ligamentous structures in rotation and combined flexion-rotation of the lumbar spine.

We carried out experiments on whole cadaveric lumbar spines in order to determine the role that each of the capsulo-ligamentous structures play in axial rotation in the neutral position and in the flexed position. Eight specimens were first tested intact, then after division of all the apophyseal joint capsules between L1 and the sacrum. Another five specimens were also first tested intact, then after division of the supra- and interspinous ligaments and yellow ligament, and finally after cutting the posterior longitudinal ligament and posterior annulus at each level as well. The results show that there is considerable variation in the axial rotation of the lumbar vertebrae within the same spine and across different spines. The apophyseal joint capsules limit rotation both in neutral and flexed positions. In flexion, the amplitude of rotation in the lumbar spine is reduced. Of the capsulo-ligamentous structures, it is the posterior annulus and the posterior longitudinal ligament that seem to play the more important role in limiting axial rotation while the spine is flexed.

Adult↗
PubMed1997

In vivo rotational stability of the kinematic rotating hinge knee prosthesis.

The in vivo rotary laxity and torsional stiffness of the knee joint were measured in 20 patients with wide intraarticular resection of the distal femoral tumor followed by reconstruction with a custom Kinematic rotating hinge endoprosthesis. The contralateral normal knee served as natural control. Twenty patients underwent 29 measurements, including 9 at the first year, 10 at the second year (4 of these also measured at year 1), and 10 at the third year (3 of these also measured at years 1 and 2; 2 also measured at year 2). The mean followup for the 15 survivors was 134 months (range, 102-156 months). The total rotatory laxity of the hinged knee was significantly greater than that of the contralateral knee. The torsional stiffness in external rotation of the hinged knee was 30.4% less than that of the contralateral knee in the first postoperative year, whereas the torsional stiffness in internal rotation was similar to that of the contralateral knee. Torsional stiffness of the hinged knee in the second year was significantly less than that of the contralateral knee whereas it was within the normal range of stiffness in the third year. The total rotatory laxity and torsional stiffness of the hinged knee in the early postoperative years could not predict the risk of late loosening. In vitro rotational stability of the rotating hinge device with axial load bearing was 6.7 and 8.1 Newton-meters (N-m) at 0 degrees and 20 degrees knee flexion, respectively, under an axial tibial load of 945 Newtons.

Adolescent↗