Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “Rotation”

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 145 records · Page 8Linked to original sources
PubMed2002

Nonlinear response of a dipolar system with rotational diffusion to a rotating field.

The rotational diffusion equation for a dipole in the presence of a rotating field is solved by expansion of the orientational distribution function in terms of spherical harmonics. For the stationary solution, the distribution function rotates bodily in angular space. The magnitude of the average dipole moment and the lag angle are studied as functions of field strength and frequency. A comparison is made with the nonlinear response calculated from approximate macroscopic relaxation equations, proposed by Shliomis [Zh. Eksp. Teor. Fiz. 61, 2611 (1972) [Sov. Phys. JETP 34, 1291 (1972)]] and by Martsenyuk et al. [Zh. Eksp. Teor. Fiz. 65, 834 (1973) [Sov. Phys. JETP 38, 413 (1974)]]. Shliomis found that for sufficiently high field, the lag angle and the absorption are multivalued functions of frequency. This is not the case for the exact solution of the rotational diffusion equation presented here. The response of a macroscopic system of interacting dipoles is calculated in a mean-field approximation for a spherical sample.

Journal Article↗
PubMed1996

Interobserver reliability in measuring flexion, internal rotation, and external rotation of the hip using a plurimeter.

OBJECTIVE: To determine reliability of the measurement of hip movements (flexion, internal rotation, and external rotation) between medical practitioners. METHODS: Six clinicians carried out measurements of hip movements on each of six patients with osteoarthritis of one hip, using a specifically designed plurimeter. RESULTS: There was no evidence of any systematic difference between medical practitioners in the measurement of hip flexion, internal rotation, or external rotation. The degree of agreement was greatest for hip flexion. CONCLUSIONS: This study has shown that measurement of range of movement at the hip is repeatable between practitioners using a simple plurimeter and may represent an examination that is suitable for monitoring progress and treatment.

Evaluation Studies as Topic↗
PubMed2000

Scintigraphic assessment of the rotated femoral head after transtrochanteric rotational osteotomy for osteonecrosis.

BACKGROUND: The purpose of this study was to assess the usefulness of bone scintigraphy in predicting progressive collapse of the femoral head after transtrochanteric rotational osteotomy for the treatment of osteonecrosis of the femoral head. METHODS: We studied thirty-three hips in thirty patients with osteonecrosis of the femoral head who had undergone transtrochanteric rotational osteotomy. There were twenty male and ten female patients, with a mean age of 34.4 years at the time of the operation. The mean duration of follow-up was 10.0 years. According to the staging system of Ficat and Arlet, there were nineteen stage-2 hips and fourteen stage-3 hips at the time of the operation. Conventional anteroposterior and lateral radiographs were assessed. In addition, bone scans were performed at three weeks after the operation to predict the outcome with regard to the rotated femoral head. On the basis of the location of low scan activity within the femoral head, the scintigraphic findings were classified into one of two categories: type A if there was no low scan activity in the weight-bearing area of the femoral head or type B if low scan activity occupied the entire weight-bearing area. Six hips with collapse were studied histologically. RESULTS: Postoperative scintiscans revealed sixteen type-A hips and seventeen type-B hips. Of the type-A hips, only three exhibited progressive collapse of the femoral head after the osteotomy, whereas fourteen of the type-B hips exhibited progressive collapse. A significant association was found between the postoperative scintigraphic findings and the final radiographic result (p < 0.01). CONCLUSIONS: Bone scintiscans made three weeks after transtrochanteric rotational osteotomy were useful for predicting the final clinical result.

Adult↗
PubMed1991

[The arrangement of trans-septal fibers in rotated and non-rotated emerged teeth in beagle dogs].

Transseptal fibers of the periodontal ligament are thought to play a role in relapse after orthodontic correction of rotated teeth. The aim of this study was to compare the location of the attachment site and the arrangement of the transseptal fibers in rotated emerged and non-rotated emerged teeth. In five dogs, unilaterally, the first upper premolars were reimplanted into a rotated position, before emergence. Histological evaluation showed that in the experimental as well as in the control specimens transseptal fibers developed. In all cases transseptal fibers bridged the shortest distance between two adjacent teeth. It was concluded that the attachment site of the transseptal fibers is not determined by tooth anatomy itself, but by the tooth position and its orientation in the dental arch during transseptal fiber development.

Animals↗
PubMed1983

[Dissolution determination in the rotating flask model. Effect of rotation rate and fluid volume on the solubility determination of standard test tablets in the Resotest dissolution tester].

The influence of two important factors, the rotational speed and the fluid volume within the system, on the release characteristics of prednisone-test tablets in the rotating flask dissolution-tester (Resotest-apparatus after Koch) has been investigated. As a result, standard conditions for dissolution experiments with the rotating flask model, i.e. a mean rotation number of 30 r.p.m. and an actual fluid volume of 500 ml, are proposed.

Chemistry, Pharmaceutical↗
PubMed2006

Using support vector machines to optimally classify rotator cuff strength data and quantify post-operative strength in rotator cuff tear patients.

Shoulder strength data are important for post-operative assessment of shoulder function and have been used in diagnosis of rotator cuff pathology. Support vector machines (SVM) employ complex analysis techniques to solve classification and regression problems. A SVM, a machine learning technique, can be used for analysis and classification of shoulder strength data. The goals of this study were to determine the diagnostic competency of SVM based on shoulder strength data and to apply SVM analysis in efforts to derive a single representative shoulder strength score. Data were taken from fourteen isometric shoulder strength measurements of each shoulder (involved and uninvolved) in 45 rotator cuff tear patients. SVM diagnostic proficiency was found to be comparable to reported ultrasound values. Improvement of shoulder function was accurately represented by a single score in pairwise comparison of the pre-operative and the 12 month post-operative group (P < 0.004). Thus, the SVM-based score may be a promising metric for summarizing rotator cuff strength data.

Artificial Intelligence↗
PubMedDate not supplied

Massive rotator cuff tears: the result of partial rotator cuff repair.

Massive rotator cuff tears often defy traditional repair techniques and have led to a variety of treatment recommendations. We reviewed retrospectively the results of partial repair of massive rotator cuff tears in 24 patients. Overall results were excellent in 11 patients (46%), good in 5 (21%), fair in 7 (29%), and poor in 1 (4%). Ninety-two percent of patients were satisfied with the result of surgery. Satisfactory pain relief was achieved in 83% (P<.001). Active elevation improved from 114 degrees to 154 degrees , and no patient lost strength after surgery. The ability to raise the arm to at least 135 degrees improved from 13 patients preoperatively to 21 patients postoperatively. This series serves as a basis of comparison to debridement, tendon transfers, and tendon augmentation procedures for the treatment of massive irreparable rotator cuff tears.

Adult↗
PubMedDate not supplied

[Latissimus dorsi transfer in case of irreparable rotator cuff tear--a comparative analysis of primary and failed rotator cuff surgery, in dependence of deficiency grade and additional lesions].

AIM: Latissimus dorsi transfer is a difficult operation with a long rehabilitation. We investigated if it is worth the effort. METHOD: We used this technique in 22 patients with an inoperable rotator cuff tear (15 patients had a primary surgery, 7 patients were operated after failed prior rotator cuff repair). Additional lesions were also considered in the analysis. The average follow up was 9 months. The results were divided in 4 groups: severe indication, primary reconstruction, 3-tendon rupture, secondary reconstruction. RESULTS: The best results were achieved by the group "severe indication" (raising in the Constant score from 38 to 79 points). The group with primary surgery (increasing from 43 to 67 points) had better results than the group with failed prior reconstruction (increasing from 33 to 62 points). In case of additional rupture of the subscapularis tendon (45 to 58 points) or insufficiency of the deltoid muscle (33 to 45 points) the results are not satisfactory. The postoperative pain relief was felt as the predominant improvement. CONCLUSION: The latissimus dorsi transfer is a valuable and safely reproducible procedure. Depending on the preoperative grade of deficiency it is possible to achieve a shoulder function of 60-90 % in comparison to the healthy shoulder. Despite the difficult operation technique and the long rehabilitation phase, the LDP is worth the effort on patients with irreparable rotator cuff tears. It is not the right procedure in cases of defect arthropathy--in these cases inverted shoulder prosthesis should be used.

Aged↗
PubMedDate not supplied

MR evaluation of rotator cuff impingement: correlation with confirmed full-thickness rotator cuff tears.

OBJECTIVE: To clarify the efficacy of MRI for the evaluation of rotator cuff impingement beneath the coracoacromial arch, MRI findings were correlated with confirmed full-thickness rotator cuff tears (FTRCTs). MATERIALS AND METHODS: Thirty-four shoulders with FTRCT and 49 control shoulders without FTRCT were selected for this study. Direct measurement of the subacromial space (SAS) and MRI grading of SAS and subacromioclavicular space (SACS) were correlated with FTRCT. In addition, the MRI impingement score (sum of SAS grade and SACS grade) was correlated with age and FTRCT. RESULTS: Direct measurement of the SAS showed poor correlation with FTRCT. The SAS grade showed significant correlation with FTRCT; however, SACS grade showed poor correlation. Shoulders with higher MRI impingement scores were associated with FTRCT in patients over 40 years of age. CONCLUSION: The MRI sign of rotator cuff impingement is fairly reliable and helpful in discriminating patients with FTRCT, especially older patients.

Acromioclavicular Joint↗
PubMed2004

Electromyographic analysis of the rotator cuff and deltoid musculature during common shoulder external rotation exercises.

STUDY DESIGN: Prospective single-group repeated-measures design. OBJECTIVES: To quantify electromyographic (EMG) muscle activity of the infraspinatus, teres minor, supraspinatus, posterior deltoid, and middle deltoid during exercises commonly used to strengthen the shoulder external rotators. BACKGROUND: Exercises to strengthen the external rotators are commonly prescribed in rehabilitation, but the amount of EMG activity of the infraspinatus, teres minor, supraspinatus, and deltoid during these exercises has not been thoroughly studied to determine which exercises would be most effective to achieve strength gains. METHODS AND MEASURES: EMG measured using intramuscular electrodes were analyzed in 10 healthy subjects during 7 shoulder exercises: prone horizontal abduction at 100 degrees of abduction and full external rotation (ER), prone ER at 90 degrees of abduction, standing ER at 90 degrees of abduction, standing ER in the scapular plane (45 degrees abduction, 30 degrees horizontal adduction), standing ER at 0 degrees of abduction, standing ER at 0 degrees of abduction with a towel roll, and sidelying ER at 0 degrees of abduction. The peak percentage of maximal voluntary isometric contraction (MVIC) for each muscle was compared among exercises using a 1-way repeated-measures analysis of variance (P<.05). RESULTS: EMG activity varied significantly among the 7 exercises. Sidelying ER produced the greatest amount of EMG activity for the infraspinatus (62% MVIC) and teres minor (67% MVIC). The greatest amount of activity of the supraspinatus (82% MVIC), middle deltoid (87% MVIC), and posterior deltoid (88% MVIC) was observed during prone horizontal abduction at 100 degrees with full ER. CONCLUSIONS: Results from this study provide initial information to develop rehabilitation programs. It also provides information helpful for the design and conduct of future studies.

Adult↗
PubMed2006

A probabilistic model of glenohumeral external rotation strength for healthy normals and rotator cuff tear cases.

The reigning paradigm of musculoskeletal modeling is to construct deterministic models from parameters of an "average" subject and make predictions for muscle forces and joint torques with this model. This approach is limited because it does not perform well for outliers, and it does not model the effects of population parameter variability. The purpose of this study was to simulate variability in musculoskeletal parameters on glenohumeral external rotation strength in healthy normals, and in rotator cuff tear case using a Monte Carlo model. The goal was to determine if variability in musculoskeletal parameters could quantifiably explain variability in glenohumeral external rotation strength. Multivariate Gamma distributions for musculoskeletal architecture and moment arm were constructed from empirical data. Gamma distributions of measured joint strength were constructed. Parameters were sampled from the distributions and input to the model to predict muscle forces and joint torques. The model predicted measured joint torques for healthy normals, subjects with supraspinatus tears, and subjects with infraspinatus-supraspinatus tears with small error. Muscle forces for the three conditions were predicted and compared. Variability in measured torques can be explained by differences in parameter variability.

Computer Simulation↗
PubMed2006

Time-resolved fMRI of mental rotation revisited--dissociating visual perception from mental rotation in female subjects.

Functional neuroimaging studies have demonstrated that mental rotation paradigms activate a network of spatially distributed cortical areas rather than a discrete brain region. Although the neuro-anatomical nodes of the rotation network are well established, their specific functional role is less well identified. It was the aim of the present study to dissociate network components involved in the visual perception of 3D cubic objects from regions involved in their mental spatial transformation. This was achieved by desynchronizing the time course of the perceptional process (i.e., stimulus duration) from the duration of the cognitive process (i.e., reaction times) and by comparing these with the temporal characteristics of the hemodynamic response functions (HRFs) in regions of interest. To minimize intersubject variability, an all-female subject group was chosen for this investigation. Time-resolved fMRI analysis revealed a significant increase in the full width at half maximum (FWHM) of the HRF with reaction times in the supplementary motor area (pre-SMA), in the bilateral premotor cortex (PMd-proper), and in the left parietal lobe (PP). The FWHM in visual system components such as the bilateral lateral occipital complex (LOC) and dorsal extrastriate visual areas (DE) was constant across trials and roughly equal to the stimulus duration. These findings suggest that visual system activation during mental rotation reflects visual perception and can be dissociated from other network components whose response characteristics indicates an involvement in the mental spatial transformation itself.

Adult↗
PubMed2002

Coupling proton movements to c-ring rotation in F(1)F(o) ATP synthase: aqueous access channels and helix rotations at the a-c interface.

F(1)F(o) ATP synthases generate ATP by a rotary catalytic mechanism in which H(+) transport is coupled to rotation of a ring of c subunits within the transmembrane sector of the enzyme. Protons bind to and then are released from the aspartyl-61 residue of subunit c at the center of the membrane. Proton access channels to and from aspartyl-61 are thought to form in subunit a of the F(o) sector. Here, we summarize new information on the structural organization of subunit a and the mapping of aqueous accessible residues in the fourth and fifth transmembrane helices (TMHs). Cysteine substituted residues, lying on opposite faces of aTMH-4, preferentially react with either N-ethyl-maleimide (NEM) or Ag(+). We propose that aTMH-4 rotates to alternately expose each helical face to aspartyl-61 of subunit c during the proton transport cycle. The concerted helical rotation of aTMH-4 and cTMH-2 are proposed to be coupled to the stepwise mechanical movement of the c-rotor.

Aquaporins↗
PubMed1976

A spectroscopic technique for measuring slow rotational diffusion of macromolecules. 2: Determination of rotational correlation times of proteins in solution.

Experiments have been performed to test the validity of measurements of slow rotational diffusion using eosin isothiocyanate as a probe. When eosin-protein conjugates are covalently bound to Sepharose 4B, the dichroism of the flash-induced absorption transient does not decay with time. The magnitude of the dichroism is smaller than for eosin in solid solution. These results, together with measurements with highly viscous solutions, demonstrate the existence of a rapid but restricted independent motion of the eosin probe. This causes a partial loss of pf dochroism leaving a residual dichroism whose time dependence is determined by the rotational motion of the protein. Rotational correlation times in the microsecond-millisecond time range have been determined for eosinprotein conjugates dissolved in glycerol-water mixtures of varying viscosity. The measured values are in good agreement with theoretical predictions and show the correct dependence on the viscosity of the medium and the size and state of association of the protein.

Animals↗
PubMed2003

Subunit rotation of vacuolar-type proton pumping ATPase: relative rotation of the G and C subunits.

Vacuolar-type ATPases V1V0 (V-ATPases) are found ubiquitously in the endomembrane organelles of eukaryotic cells. In this study, we genetically introduced a His tag and a biotin tag onto the c and G subunits, respectively, of Saccharomyces cerevisiae V-ATPase. Using this engineered enzyme, we observed directly the continuous counter-clockwise rotation of an actin filament attached to the G subunit when the enzyme was immobilized on a glass surface through the c subunit. V-ATPase generated essentially the same torque as the F-ATPase (ATP synthase). The rotation was inhibited by concanamycin and nitrate but not by azide. These results demonstrated that the V- and F-ATPase carry out a common rotational catalysis.

Actin Cytoskeleton↗
PubMed1994

Tendon degeneration and chronic shoulder pain: changes in the collagen composition of the human rotator cuff tendons in rotator cuff tendinitis.

OBJECTIVES: To analyse the collagen composition of normal adult human supraspinatus tendon and to compare with: (1) a flexor tendon (the common biceps tendon) which is rarely involved in any degenerative pathology; (2) degenerate tendons from patients with chronic rotator cuff tendinitis. METHODS: Total collagen content, collagen solubility and collagen type were investigated by hydroxyproline analysis, acetic acid and pepsin digestion, cyanogen bromide peptide analysis, SDS-PAGE and Western blotting. RESULTS: The collagen content of the normal cadaver supraspinatus tendons (n = 60) was 96.3 micrograms HYPRO/mg dry weight (range 79.3-113.3) and there was no significant change across the age range 11 to 95 years. There was no significant difference from the common biceps tendon [93.3 (13.5) micrograms HYPRO/mg dry weight, n = 24]. Although extremely insoluble in both acetic acid and pepsin, much of the collagen was soluble after cyanogen bromide digestion [mean 47.9% (29.8)]. Seventeen per cent (10/60) of the 'normal' cadaver supraspinatus tendon sample contained more than 5% type III collagen, although none of the common biceps tendons had significant amounts. Degenerate supraspinatus and subscapularis tendons had a reduced collagen content [83.8 (13.9) micrograms/mg dry weight and 76.9 (16.8) micrograms/mg dry wt respectively) and were more soluble in acetic acid, pepsin and cyanogen bromide (p < 0.001). Eighty two per cent (14/17) of supraspinatus tendons and 100% (8/8) of subscapularis tendons from patients with tendinitis contained more than 5% type III collagen. CONCLUSIONS: The changes in collagen composition in rotator cuff tendinitis are consistent with new matrix synthesis, tissue remodelling and wound healing, in an attempt to repair the tendon defect, even in old and degenerate tendons. An increase in type III collagen in some 'normal' cadaver supraspinatus tendons is evidence that changes in collagen synthesis and turnover may precede tendon rupture. These changes may be the result of repeated minor injury and microscopic fibre damage or a consequence of local factors such as reduced vascular perfusion, tissue hypoxia, altered mechanical forces and the influence of cytokines. These collagenous changes may accumulate with age and substantially weaken the tendon structure, predisposing the tendon to rotator cuff tendinitis and eventual tendon rupture.

Adolescent↗
PubMed1991

An experimental study in dogs of transseptal fiber arrangement between teeth which have emerged in rotated or non-rotated positions.

Transseptal fibers of the periodontal ligament are thought to play a role in relapse after orthodontic derotation. The aim of this study was to compare the location of the attachment site and the arrangement of the transseptal fibers in rotated emerged and non-rotated emerged teeth. In five dogs, unilaterally, the first upper premolars were replaced into a rotated position, before emergence. Histological evaluation showed that transseptal fibers developed in the experimental as well as in the control specimens. In all cases, transseptal fibers bridged the shortest distance between two adjacent teeth. It was concluded that the attachment site of the transseptal fibers was not determined by the tooth anatomy itself, but by the tooth position and its orientation in the dental arch during transseptal fiber development.

Animals↗
PubMed1994

Interlaboratory variability of rotational chair test results. Interlaboratory Rotational Chair Study Group.

Test-retest reliability of rotational chair testing for a single facility has previously been examined by others. The actual data analysis methods, however, have received far less attention. The variety of both hardware and software currently used theoretically may affect the results for a given subject tested at different facilities. The purposes of this study were, first, to quantify the amount of variability in the analysis of identical raw data files at multiple rotational chair testing facilities by using automated analysis; second, to evaluate the effect of operator intervention on the analysis; and third, to identify possible sources of variability. Raw data were collected from 10 normal subjects at 0.05 Hz and 0.5 Hz (50 degrees per second peak velocity). Diskettes containing raw electro-oculogram data files were then distributed to eight participating laboratories for analysis by two methods: (1) using automated analysis algorithms and (2) using the same algorithms but allowing operator intervention into the analysis. Response parameters calculated were gain and phase (re: velocity). The SD of gain values per subject for automated analysis ranged from 0.01 to 0.32 gain units and of phase values from 0.4 to 13.7 degrees. For analysis with operator intervention, the SD of gain values ranged from 0.02 to 0.10 gain units and of phase values from 0.4 to 4.4 degrees. The difference between automated analysis and analysis with operator intervention was significant for gain calculations (p < 0.02) but not for phase calculations (p > 0.05). This study demonstrates significant variability in automated analysis of rotational chair raw data for gain and phase.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗