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PubMed1999

Opioid rotation in chronic non-malignant pain patients. A retrospective study.

BACKGROUND: The clinical advantage of opioid rotation is probably due to incomplete cross-tolerance favouring analgesia more than adverse effects. The objectives of opioid rotation in chronic non-malignant patients are 1): rotation between different long-acting opioids (LAO) to improve analgesia and reduce side-effects, and 2): rotation from short-acting opioids (SAO) to LAO to establish stable analgesia in order to minimise withdrawal symptoms, risk of tolerance and addiction. METHODS: A retrospective analysis of 37 rotations between different LAO and 59 rotations from SAO to LAO. RESULTS: The main reason for opioid rotation was insufficient pain relief. Opioid rotations resulted in significantly better pain control in 59% (CI95=49-76%) of the patients rotated between different LAO and 73% (CI95=60-84%) of the patients rotated from SAO to LAO. During rotations symptoms of withdrawal and overdosing were relatively frequent in both groups. No significant dose changes were seen when rotating between different LAO. However, the consequence of rotation from SAO to LAO was a 74% increase in the opioid dose (CI95=30-117%). CONCLUSION: Opioid rotations between different LAO resulted in better pain control and fewer side-effects at dose levels predicted to be equianalgesic. The majority of the patients rotated from SAO to LAO obtained improved analgesia, but the cost was a 74% increase in the opioid dose.

Adult↗
PubMed1992

Effect of viewing distance and location of the axis of head rotation on the monkey's vestibuloocular reflex. I. Eye movement responses.

1. The vestibuloocular reflex (VOR) stabilizes images on the retina against movements of the head in space. Viewing distance, target eccentricity, and location of the axis of rotation may influence VOR responses because rotation of the head about most axes in space rotates and translates the eyes relative to visual targets. To study the VOR response to combined rotation and translation, monkeys were placed on a rate table and rotated briefly in the dark about a vertical axis that was located in front of or behind the eyes. The monkeys fixated a near or far visual target that was extinguished before the rotation. Eye movements were recorded from both eyes by the use of the search coil technique. 2. Peak eye velocity evoked by the VOR was linearly related to vergence angle for any axis of rotation. The percent change in the VOR with near target viewing relative to far target viewing at a vergence angle of 20 degrees was linearly related to the location of the axis of rotation. Axes located behind the eyes produced positive changes in VOR amplitude, and axes located in front of the eyes produced negative changes in VOR amplitude. An axis of rotation located in the coronal plane containing the centers of rotation of the eyes produced no modification of VOR amplitude. For any axis, the VOR compensated for approximately 90% of the translation of the eye relative to near targets. 3. The initial VOR response was not correct in magnitude but was refined by a series of three temporally delayed corrections of increasing complexity. The earliest VOR-evoked eye movement (10-20 ms after rotation onset) was independent of viewing distance and rotational axis location. In the next 100 ms, eye speed appeared to be sequentially modified three times: within 20 ms by viewing distance; within 30 ms by otolith translation; and within 100 ms by eye translation relative to the visual target. 4. These data suggest a formal model of the VOR consisting of four channels. Channel 1 conveys an unmodified head rotation signal with a pure delay of 10 ms. Channel 2 conveys an angular head velocity signal, modified by viewing distance with a pure delay of 20 ms, but invariant with respect to the location of the axis of rotation. Channel 3 conveys a linear head velocity signal, dependent on the location of the axis of rotation, that is modified by viewing distance with a pure delay of 30 ms.(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗
PubMed2006

Symmetry types, systems and their multiplicity in the structure of adenovirus capsid. II. Rotational facet groups of five-, three- and two-fold symmetry axes.

The icosahedral adenovirus capsid has three rotational symmetry axes of different types. The six five-fold, ten three-fold and the fifteen two-fold axes have two superficial points each, altogether 62. The axes determine the number and location of the identical rotational facet groups and that during the different rotational phases which other regular facets and with what multiplicity shall be covered by them. The number of rotational facets of the five-, three- and two-fold rotational symmetry axes is 4, 6.66 and 10, respectively. In all the three cases, there are two kinds of possible arrangements of the facets. During the rotation--when the facets of the facet group placed on one by one to the neighbouring identical facet groups--at the five-fold axes, the facets of the rotational facet group get into cover position 12 times with all the 20 regular capsid facets, 20 times at the three-fold axes, and 30 times at the two-fold axes in a way that a different facet combination (facet hit) falls to every facet, and the original symmetry is not disturbed. After all, this means 240, 400 and 600 facet combinations, i.e. multiplicity in case of five-, three- and two-fold symmetry axes respectively, and these numbers correspond with that of the theoretically possible variations. The same results can be calculated by multiplying the number of real rotations of the capsid bringing the body into itself, i.e. the number 60 with the number of facets contributing to the five-, three- and two-fold rotational phases. The other way of the determination of multiplicity takes into account that all the facet groups of the capsid rotate simultaneously during all the rotational phases, and this multiplies the number of multiplicity with the number of the rotational types five-, three- and two-fold which result in one and the same multiplicity number in the case of five-, three- and two-fold symmetry, alike 1200. Perpendicular to the five-fold symmetry axes with the line of intersection drawn horizontally in the middle along the 6 geodetic ribbon like motifs a regular decagonal intersection forms and the capsid can be cut into two equal parts, in which the polypeptides show a 72 degree rotation from each other, but with a proper rotation the polypeptides get into a congruent position, which means 300 or 600 specific facet combinations. The capsid similar to the icosahedron has also 15 virtual mirror planes which divide the capsid into two, identically arranged halves, forming six right angle triangles on each facet, altogether 120 smaller rectangular so-called Mobius-triangles on the surface. In the three-fold symmetry axis of the facets, these triangles in two separate groups of three can be rotated symmetrically with 120 degrees according to the orientation of the polypeptide subunits in a way that the hexon and other polypeptides too nearly cover each other. Consequently, the adenovirus capsid is a symmetrically arranged body in which several various symmetry types and symmetry systems can be found and their structural symmetry elements exist simultaneously and covering each other. The icosahedral symmetry types and systems are valid and functional simultaneously and in parallel with great multiplicity, but the existence of more than 1500 structural elements in several depth levels, their order of location and distribution make the symmetry of the capsid richer and more complex.

Adenoviridae↗
PubMed2006

[Symmetry types, systems and multiplicity of the structure of adenovirus capsid. II. Rotational facet-groups of five-, three- and two-fold symmetry axes].

The icosahedral adenovirus capsid has three rotational axes of different types. The six five-fold, ten three-fold and the fifteen two-fold axes have two superficial points each, altogether 62. The axes determine the number and location of the identical rotational facet groups and that during the different rotational phases which other regular facets and with what multiplicity shall be covered by them. The number of rotational facets of the five-, three- and two-fold rotational symmetry axes is 4, 6.66 and 10, respectively. In all the three cases, there are two kinds of possible arrangements of the facets. During the rotation - when the facets of the facet group placed on one by one to the neighbouring identical facet groups - at the five-fold axes, the facets of the rotational facet group get into cover position 12 times with all the 20 regular capsid facets, 20 times at the three-fold axes, and 30 times at the two-fold axes in a way that a different facet combination (facet hit) falls to every facet, and the original symmetry is not disturbed. After all, this means 240, 400 and 600 facet combinations, i.e. multiplicity in case of five-, three- and two-fold symmetry axes respectively, and these numbers correspond with that of the theoretically possible variations. The same results can be calculated by multiplying the number of real rotations of the capsid bringing the body into itself i.e. the number 60 with the number of facets contributing to the five-, three- and two-fold rotational phases. The other way of the determination of multiplicity takes into account that all the facet groups of the capsid rotate simultaneously during all the rotational phases, and this multiplies the number of multiplicity with the number of the rotational types five-, three- and two-fold which result in one and the same multiplicity number in the case of five-, three- and two-fold symmetry, alike 1200. Perpendicular to the five-fold symmetry axes with the line of intersection drawn horizontally in the middle along the 6 geodetic ribbon like motifs a regular decagonal intersection forms and the capsid can be cut into two equal parts, in which the polypeptides show a 72 degree rotation from each other, but with a proper rotation the polypeptides get into a congruent position, which means 300 or 600 specific facet combinations. The capsid similar to the icosahedron has also 15 virtual mirror planes which divide the capsid into two, identically arranged halves, forming six right angle triangles on each facet, altogether 120 smaller rectangular so-called Mobius-triangles on the surface. In the three-fold symmetry axis of the facets, these triangles in two separate groups of three can be rotated symmetrically with 120 degrees according to the orientation of the polypeptide subunits in a way that the hexon and other polypeptides too nearly cover each other. Consequently, the adenovirus capsid is a symmetrically arranged body in which several various symmetry types and symmetry systems can be found and their structural symmetry elements exist simultaneously and covering each other. The icosahedral symmetry types and systems are valid and functional simultaneously and in parallel with great multiplicity, but the existence of more than 1500 elements in several depth levels, their order of location and distribution make the symmetry of the capsid richer and more complex.

Adenoviridae↗
PubMed1991

Characterization and development of rotational behavior in Helisoma embryos: role of endogenous serotonin.

Cilia-driven rotational behavior displayed by embryos of the pond snail Helisoma trivolvis was characterized in terms of its behavioral subcomponents, developmental changes, and response to exogenous serotonin. Rotation was found to be a complex behavior characterized by four parameters; rotational direction, rotation rate, rotational surges, and periods of inactivity. These parameters all exhibited characteristic developmental changes from embryonic stage E15 through stage E30. Notably, both rotation rate and frequency of rotational surges increased from stage E15 to E25 and declined to an intermediate level by stage E30. It appeared that the developmental increase in overall rotation rate was caused primarily by an increase in surge frequency, rather than an increase in the rate of nonsurge rotation. Immersion of embryos inserotonin-containing pond water resulted in a dose-dependent, reversible increase in rotation rate as well as a dose-dependent, reversible decrease in surge frequency. The serotonin antagonist, mianserin, abolished the excitatory effect of exogenous serotonin. Furthermore, application of mianserin alone reduced rotation rate and virtually abolished rotational surges. Taken together, these pharmacological results suggest that endogenous serotonin is responsible for generating rotational surges. Given that early embryos contain only a single pair of serotonergic neurons (Goldberg and Kater, 1989) during the stages when rotational surges are expressed, these results also prompt the hypothesis that these neurons, embryonic neurons C1, act as cilioexcitatory motor neurons during embryonic development.

Animals↗
PubMed1995

High-speed rotation and speed stability of the sodium-driven flagellar motor in Vibrio alginolyticus.

The Na(+)-driven flagellar motor in Vibrio alginolyticus rotates very fast. Rotation of a single flagellum on a stuck cell was measured by laser darkfield microscopy with submillisecond temporal resolution. The rotation rate increased with increasing external concentration of NaCl, and reached 1000 r.p.s. at 300 mM NaCl. The Na+ influx through the motor should determine the rotation period (tau) and affect the speed stability. Fluctuation of the rotation period was analyzed at various rotation rates (from approximately 50 r.p.s. to approximately 1000 r.p.s.), which were changed by changing the external concentration of NaCl and the addition of a protonophore or a specific inhibitor. At high rotation rates (over 400 r.p.s.), the observed rotation was stable, and the standard deviation of tau (sigma tau) ranged from 7% to 16% of the average rotation period (< tau >). At low rotation rates (under 100 r.p.s), the rotation period tended to fluctuate, and the distributions of tau were non-Gaussian. The value of sigma tau ranged from 10 to 30% of < tau >. However, the observed minimum value of sigma tau at various rotation rates was approximately equal to the calculated standard deviation due to the rotational diffusion of the flagellar filament. These results suggest that the torque was stably generated at various Na+ influxes through the motor. We observed large fluctuations that cannot be explained by rotational diffusion. We discuss the factors that induce the large fluctuation.

Biophysical Phenomena↗
PubMed1999

Variation of rotation moment arms with hip flexion.

Excessive flexion and internal rotation of the hip is a common gait abnormality among individuals with cerebral palsy. The purpose of this study was to examine the influence of hip flexion on the rotational moment arms of the hip muscles. We hypothesized that flexion of the hip would increase internal rotation moment arms and decrease external rotation moment arms of the primary hip rotators. To test this hypothesis we measured rotational moment arms of the gluteus maximus (six compartments), gluteus medius (four compartments), gluteus minimus (three compartments) iliopsoas, piriformis, quadratus femoris, obturator internus, and obturator externus. Moment arms were measured at hip flexion angles of 0, 20, 45, 60, and 90 degrees in four cadavers. A three-dimensional computer model of the hip muscles was developed and compared to the experimental measurements. The experimental results and the computer model showed that the internal rotation moment arms of some muscles increase with flexion; the external rotation moment arms of other muscles decrease, and some muscles switch from external rotation to internal rotation as the hip is flexed. This trend toward internal rotation with hip flexion was apparent in 15 of the 18 muscle compartments we examined, suggesting that excessive hip flexion may exacerbate internal rotation of the hip. The gluteus maximus was found to have a large capacity for external rotation. Enhancing the activation of the gluteus maximus, a muscle that is frequently underactive in persons with cerebral palsy, may help correct excessive flexion and internal rotation of the hip.

Biomechanical Phenomena↗
PubMed2001

The anatomy and histology of the rotator interval capsule of the shoulder.

Forty-seven rotator interval regions from fetuses and 10 fresh-frozen rotator interval regions from adult cadavers were evaluated by gross dissection and light microscopy. Specimens from adults also were evaluated with ultrasound and magnetic resonance imaging. An analysis of 37 fetal specimens (> 14 weeks gestation) revealed two rotator interval types: Type I (9 of 37) was defined by a contiguous bridge of capsule consisting of poorly organized collagen fibers. A Type II rotator interval (28 of 37) had a complete defect covered by only a thin layer of synovium. Similar to the Type II rotator interval in the fetus, a rotator interval defect was present in six of eight specimens from adults. Histologically, the capsular tissue within the rotator interval consisted of poorly organized collagen fibers in specimens from the fetus and adult. Maximal opening of the rotator interval was seen by ultrasound with internal rotation and downward traction of the hyperextended arm in the coronal, oblique, and sagittal planes. Magnetic resonance imaging of the rotator interval region permitted anatomic evaluation. The complete absence of tissue in 28 of 37 fetuses suggests that the rotator interval defect is congenital. The authors recommend that surgeons carefully evaluate the integrity of the tissue within the rotator interval. When rotator interval closure is desired such as in patients with a persistent sulcus sign after arthroscopic stabilization, suturing the edges of more substantial tissue immediately adjacent to the boundaries of the rotator interval region would seem prudent.

Adult↗
PubMed1996

An electromyographic study of unresisted trunk rotation with normal velocity among healthy subjects.

STUDY DESIGN: An axial rotation tester was designed and fabricated for the study. This allowed stabilization of seated subjects (hip down) and coupling of shoulders, permitting axial rotation and coupled lateral flexion. Using this device, a "flexion-extension free" axial rotation was executed for studying its characteristics. OBJECTIVES: To determine the mechanism of initiation, sustenance, and execution of axial rotation. This was planned to be done by determining the phasic relationship of various torso muscles in the initiation, execution, and termination of axial rotation. Another objective was to determine the total and relative contribution of torso muscles in axial rotation and the small segments of these activities. SUMMARY OF BACKGROUND DATA: There only are a few studies conducted on axial rotation. Generally, these have investigated isometric maximal voluntary contraction in neutral or prerotated postures. The two studies that have reported isokinetic axial rotation have investigated maximal efforts. No study in literature has reported initiation, termination, and execution of unresisted normal velocity axial rotation. METHODS: Fifty healthy young subjects executed a full cycle of axial rotation, starting from neutral position to their extreme left, continuing to their extreme right, and finally moving to the neutral posture in one smooth motion without stopping anywhere. The electromyographic results of external obliques, internal obliques, rectus abdominis, pectoralis major, erectores spinae at T10 and L3, and latissimus dorsi were measured bilaterally simultaneously during this trunk rotation. The timing and relative magnitude analyses were done to determine the global and individual muscle contributions in axial rotation. The correlation between electromyographic and angular displacement, and nonlinear curve fitting regression analyses were performed to decipher individual muscles behavior. RESULTS: The pattern of muscle activation was variable. However, contralateral external obliques, ipsilateral erector spinae, and latissimus dorsi became active before other muscles. These were agonists and the others were antagonists or stabilizers. The agonists contributed 65% of the total electromyographic output, whereas antagonists and stabilizers contributed 35%. The muscle activities during onset and offset periods were biphasic with significantly different slopes. CONCLUSIONS: It was concluded that the axial rotation is achieved through the activities of agonists, and return to neutral position is because of elastic recoil controlled by agonistic muscles. A range of approximately 10-15 degrees on either side of the anatomical midsagittal plane involves little muscle effort, but beyond this region, the osteoligamentous structures become stiff and require increasing effort to execute axial rotation.

Abdominal Muscles↗
PubMed2003

Rotational constraint in posterior-stabilized total knee prostheses.

Rotational stresses from box-post impingement have been implicated in the loosening of posterior-stabilized total knee prostheses. A bench model was constructed to assess the forces generated by tibiofemoral rotation. Rotational torque under load was measured in two different posteriorstabilized total knee prostheses using an axial-torsion load cell at 0 degrees, 20 degrees, and 40 degrees flexion over 20 degrees internal and external rotation. The Sigma posterior-stabilized prosthesis generated little torque through 5 degrees internal and external rotation. An increase in torque then occurred because of box-post impingement, generating peak torques of 17 to 18 N-m at 12 degrees to 14 degrees rotation. The bench model produced the same deformation of the polyethylene post as seen on retrieved specimens. The Scorpio posterior-stabilized prosthesis had a relatively continuous rise in generated torque from tibiofemoral conformity. Box-post impingement did not occur resulting in 32% lower torque between 12 degrees and 14 degrees rotation. Peak rotational torques of 15 to 16 N-m were reached at 19 degrees to 20 degrees rotation. Tibiofemoral conformity is the primary source of rotational constraint. Box-post impingement can be a source of additional rotational constraint. Depending on specific design features, small changes in relative tibiofemoral component rotation can more than double the generated torque. Axial rotation of the knee in vivo can generate substantial torque. Relative tibiofemoral rotational position is an important factor influencing component function and fixation.

Femur↗
PubMed2004

Direct vertebral rotation: a new technique of three-dimensional deformity correction with segmental pedicle screw fixation in adolescent idiopathic scoliosis.

STUDY DESIGN: A prospective study. OBJECTIVES: To introduce a new technique, direct vertebral rotation, and to compare the surgical results of direct vertebral rotation with those of simple rod derotation. SUMMARY OF BACKGROUND DATA: Pedicle screw fixation with a simple rod derotation maneuver enables a powerful coronal and sagittal plane correction in scoliosis surgery. However, the ability of achieving rotational correction is still unclear. METHODS: Thirty-eight adolescent idiopathic scoliosis patients treated with segmental pedicle screw fixation were analyzed. The first group (n = 17) was treated by direct vertebral rotation; the second group (n = 21) was treated by simple rod derotation. All patients had a minimum follow-up of 2 years. Having similar preoperative curve patterns, both groups were evaluated for the deformity correction, lower instrumented vertebral tilt, and spinal balance. Apical vertebral rotation was evaluated by computed tomography scans. Surgical techniques of direct vertebral rotation were as follows: a precontoured rod was inserted into segmental screws on the concave side in thoracic scoliosis; a simple rod derotation was performed; and then the screws on the juxta-apical vertebrae, both on concave and convex sides, were rotated opposite direction to the rod derotation. Then, all the screws were sequentially tightened. RESULTS: In the direct vertebral rotation group, the average preoperative apical vertebral rotation of 16.7 degrees was corrected to 9.6 degrees, showing 42.5% correction, whereas in the simple rod derotation group, the correction was negligible from 16.1 degrees to 15.7 degrees (2.4%). In the direct vertebral rotation group, the average preoperative thoracic curve of 55 degrees was corrected to 12 degrees (79.6%), and the lumbar curve of 39 degrees was corrected to 7 degrees (80.5%). In the simple rod derotation group, the preoperative thoracic curve of 53 degrees was corrected to 17 degrees (68.9%), and the lumbar curve of 39 degrees was corrected to 16 degrees (62.2%). The average lower instrumented vertebral tilt correction was 80.6% and 66.3% in the directvertebral rotation and the simple rod derotation group, respectively. There were statistically significant differences in the coronal curve, lower instrumented vertebral tilt, and rotational correction (P < 0.05, Mann-Whitney U test). Thoracic kyphosis was improved in both groups. CONCLUSIONS: Segmental pedicle screw fixation with "direct vertebral rotation" showed better rotational and coronal correction than "simple rod derotation."

Adolescent↗
PubMed1996

Three-dimensional vector analysis of the human vestibuloocular reflex in response to high-acceleration head rotations. I. Responses in normal subjects.

1. The kinematics of the human angular vestibuloocular reflex (VOR) in three dimensions was investigated in 12 normal subjects during high-acceleration head rotations (head "impulses"). A head impulse is a passive, unpredictable, high-acceleration (3,000-4,000 degrees/s2) head rotation of approximately 10-20 degrees in roll, pitch, or yaw, delivered with the subject in the upright position and focusing on a fixation target. Head and eye rotations were measured with dual search coils and expressed as rotation vectors. The first of these two papers describes a vector analysis of the three-dimensional input-output kinematics of the VOR as two indexes in the time domain: magnitude and direction. 2. Magnitude is expressed as speed gain (G) and direction as misalignment angle (delta). G is defined as the ratio of eye velocity magnitude (eye speed) to head velocity magnitude (head speed). delta is defined as the instantaneous angle by which the eye rotation axis deviates from perfect alignment with the head rotation axis in three dimensions. When the eye rotation axis aligns perfectly with the head rotation axis and when eye velocity is in a direction opposite to head velocity, delta = 0. The orientation of misalignment between the head and the eye rotation axes is characterized by two spatial misalignment angles, which are the projections of delta onto two orthogonal coordinate planes that intersect at the head rotation axis. 3. Time series of G were calculated for head impulses in roll, pitch, and yaw. At 80 ms after the onset of an impulse (i.e., near peak head velocity), values of G were 0.72 +/- 0.07 (counterclockwise) and 0.75 +/- 0.07 (clockwise) for roll impulses, 0.97 +/- 0.05 (up) and 1.10 +/- 0.09 (down) for pitch impulses, and 0.95 +/- 0.06 (right) and 1.01 +/- 0.07 (left) for yaw impulses (mean +/- 95% confidence intervals). 4. The eye rotation axis was well aligned with head rotation axis during roll, pitch, and yaw impulses: delta remained almost constant at approximately 5-10 degrees, so that the spatial misalignment angles were < or = 5 degrees. delta was 9.6 +/- 3.1 (counterclockwise) and 9.0 +/- 2.6 (clockwise) for roll impulses, 5.7 +/- 1.6 (up) and 6.1 +/- 1.9 (down) for pitch impulses, and 6.2 +/- 2.2 (right) and 7.9 +/- 1.5 (left) for yaw impulses (mean +/- 95% confidence intervals). 5. VOR gain (gamma) is the product of G and cos(delta). Because delta is small in normal subjects, gamma is not significantly different from G. At 80 ms after the onset of an impulse, gamma was 0.70 +/- 0.08 (counterclockwise) and 0.74 +/- 0.07 (clockwise) for roll impulses, 0.97 +/- 0.05 (up) and 1.09 +/- 0.09 (down) for pitch impulses, and 0.94 +/- 0.06 (right) and 1.00 +/- 0.07 (left) for yaw impulses (mean +/- 95% confidence intervals). 6. VOR latencies, estimated with a latency shift method, were 10.3 +/- 1.9 (SD) ms for roll impulses, 7.6 +/- 2.8 (SD) ms for pitch impulses, and 7.5 +/- 2.9 (SD) ms for yaw impulses. 7. We conclude that the normal VOR produces eye rotations that are almost perfectly compensatory in direction as well as in speed, but only during yaw and pitch impulses. During roll impulses, eye rotations are well aligned in direction, but are approximately 30% slower in speed.

Adult↗
PubMed1994

Influence of passive and active pendular head rotation on horizontal optokinetic nystagmus.

The influence of pendular head rotation on optokinetic nystagmus was examined using a vestibulo-optic stimulator (pendular rotating chair with an optic cylinder) to study passive head rotation, and an optic cylinder which was rotated by a motor fixed to the head to study active head rotation. Pendular head rotation and optic stimuli were simultaneously and independently applied horizontally. The optic cylinder consisted of 12 vertical stripes rotating at a uniform velocity of 30 degrees/s or 90 degrees/s. Passive pendular head rotation was applied at a frequency of 0.1 Hz and a peak angular velocity of 30 degrees/s. Active head rotation was applied for a period of approximately 10 s, and at an amplitude of approximately 50 degrees. Optokinetic nystagmus was enhanced when the head was rotated in the opposite direction to the optic cylinder. However, when the head and the optic cylinder were rotated in the same direction, optokinetic nystagmus was inhibited. There was little difference between the effects of passive and active head rotation on enhancement. However, during active head rotation, optokinetic nystagmus was less inhibited than during passive head rotation.

Adult↗
PubMed2001

Contact stress on polyethylene components of a new rotating hinge with a spherical contact surface.

OBJECTIVE: To assess the nonlinear contact stress of a new rotating hinge of our knee prosthesis at various rotation angles. DESIGN: The contact surface between the metal tibial bearing and the ultra-high-molecular weight polyethylene plate of a conventional rotating hinge is of cylindrical design. We have designed a new type of rotating hinge with a congruous spherical contact surface. BACKGROUND: The endoprosthesis for reconstruction of limb after wide resection of malignant tumor around knee usually incorporates a rotating hinge. Our new rotating hinge with a spherical contact surface incorporates the benefits of an increased contact surface and potentially increased rotational stability during axial loading. METHODS: We utilized the ABAQUS finite element program to assess the nonlinear contact stress of this new rotating hinge at rotation angles of 0 degrees, 4 degrees and 8 degrees, based on a contact force of about 2800 N. RESULTS: The results show that von Mises stress for the finite element model of the polyethylene component of this rotating hinge ranges from 4.90 x 10(-6) to 8.22 MPa at the aforementioned rotational angles. The von Mises stress is about 1.31--1.82 MPa on the major parts of the ultra-high-molecular weight polyethylene plate, including both flanks. There is a mild stress concentration on the outer edge of polyethylene component, especially at 4 degrees and 8 degrees of rotation. The maximum values of von Mises stress at the contact surface at 0 degrees, 4 degrees and 8 degrees of rotation are 5.92, 7.49 and 8.22 MPa, respectively. These contact stresses are within the safety range of the ultra-high-molecular weight polyethylene (compressive yield strength, 14 MPa). CONCLUSIONS: This new rotating hinge has an evenly distributed contact stress during axial load because of congruous contact design.

Finite Element Analysis↗
PubMed2002

Effect of head rotation on posteroanterior cephalometric radiographs.

The purpose of this study was to identify the potential projection errors of posteroanterior cephalometric radiographs due to head rotation in the vertical Z-axis. For this investigation, 20 human dry skull samples with permanent dentition were collected from the Department of Anatomy in the College of Medicine, Chosun University, Korea. They had no gross asymmetries and were well preserved. Each dry skull was rotated from 0 degrees to +/- 10 degrees at 1 degrees intervals. A vertical axis, the Z-axis, was used as a rotational axis for the exposure of 420 posteroanterior cephalometric radiographs. Most of the abscissa values of each landmark showed statistically significant differences in the head rotation from each rotational angle (P < .05), whereas the ordinate values were almost the same in all rotational angles regardless of the head rotation. The abscissa values of each landmark anterior to the vertical rotational axis displaced in the same direction as the head rotation, whereas those of other landmarks posterior to the vertical rotational axis displaced in the opposite direction. The mean differences of the abscissa values, per 1 degrees of head rotation, were larger as the landmark was located further anteroposteriorly from the vertical rotational axis and smaller as the landmark was located nearer the vertical rotational axis. In view of the projection error, a posteroanterior cephalometric radiograph is a more valuable diagnostic tool when it is exposed with no head rotation about the vertical Z-axis.

Cephalometry↗
PubMed2005

Obstetrics and gynecology resident satisfaction with an integrated, comprehensive abortion rotation.

OBJECTIVE: To evaluate obstetrics and gynecology resident satisfaction with a comprehensive, integrated abortion rotation. METHODS: The University of California, San Francisco obstetrics and gynecology residency program includes a 6-week PGY-3 family planning rotation at an in-hospital clinic where abortions are provided up to 23 weeks of gestation. Residents annually evaluate the educational value of all clinical rotations on a 5-point Likert scale, with 5 indicating "maximum value," and 1 "no value." Using data from 1998-2003, we compared ratings of the family planning rotation with all other PGY-3 rotations. We also surveyed residents 1 to 3 years after graduation to assess the rotation qualitatively and quantitatively. RESULTS: Forty residents completed the abortion training, none opted out of training, and all completed the evaluations. Of all rotations in the third year, the family planning rotation was the highest rated (4.70), was similar in value to a high-volume surgical rotation (4.51, P > .10) and the elective rotation (4.45, P >.05), and surpassed the average score for all inpatient rotations (4.00, P < .001), continuity clinic (4.10, P < .001), and outpatient clinical experiences (4.06, P <.01). According to residency graduates, the family planning rotation was rated 4.8 (where 5 indicates "far greater value" than other rotations), and 85% of respondents rated it of "maximum learning value". CONCLUSION: Obstetrics and gynecology residents place high value in the University of California, San Francisco PGY-3 family planning rotation during their training and in their first years of practice.

Abortion, Induced↗
PubMed2005

Accuracy of an automated method to measure rotations of vertebrae from computerized tomography data.

STUDY DESIGN: In this phantom study, rotations of a vertebral body calculated from computerized tomography (CT) were compared to the actual rotations provided by a specially designed device incorporating a reduction gear. OBJECTIVE: The objective was to measure the accuracy of the CT and an automated software program to calculate rotations of lumbar vertebral bodies. BACKGROUND: Rotations of individual vertebrae secondary to a change in position or load can be measured in select patients by roentgen stereophotogrammetry or by using CT and a specially constructed table that creates the rotation of the torso. The purpose of this study was to measure the precision and accuracy of rotation measurements made with a CT scanner and an automated program to calculate rotation. METHODS: We constructed a phantom with a lumbar vertebra that can be rotated within a CT scanner. CT of the vertebra were obtained at angular positions of 0, 0.360 degrees , 1.080 degrees , 2.520 degrees , 5.400 degrees , 11.160 degrees , 29.160 degrees , 29.340 degrees , 29.520 degrees , 29.610 degrees , 29.700 degrees , 29.790 degrees , 29.880 degrees , and 29.889 degrees . With an automated program based on a pixel-shift algorithm, we calculated rotations of the vertebra between pairs of images. Accuracy was calculated as mean difference between the actual and the calculated rotation, and precision was calculated as the standard deviation of the differences. RESULTS: Differences between actual and calculated rotations varied from -0.083 degrees to 0.132 degrees . For rotations less than 15 degrees , mean error (accuracy) was -0.039 degrees , and the standard deviation (precision) was 0.029 degrees . For rotations greater than 15 degrees , the accuracy was 0.086 degrees , and the precision was 0.023 degrees . CONCLUSIONS: This study shows that rotations of lumbar vertebrae may be measured with CT, and an automated program to an accuracy and precision better than 0.1 degrees , comparable to that of roentgen stereophotogrammetry.

Humans↗
PubMed1989

The rotational diffusion of chloroplast phosphate translocator and of lipid molecules in bilayer membranes.

The rotational mobility of the phosphate translocator from the chloroplast envelope and of lipid molecules in the membrane of unilamellar azolectin liposomes has been investigated. The rotational dynamics of the liposome membrane were investigated by measuring the rotational diffusion of eosin-5-isothiocyanate(EITC)-labeled L-alpha-dipalmitoylglycerophosphoethanolamine (Pam2 GroPEtn) in the lipid phase of the vesicles, either in the presence or absence of the reconstituted phosphate translocator. The temperature dependence of the anisotropy decay showed that above 25 degrees C the main contribution to the anisotropy decay was caused by uniaxial anisotropic rotation of the labelled lipid molecules around the axis normal to the membrane plane. The rate of rotation of the labelled lipid molecules was strongly dependent on the viscosity of the medium (eta 1). Extrapolation to eta 1 = 0 Pa.s yielded a correlation time of phi = 20 +/- 5 ns, t = 30 degrees C, for lipid rotation with respect to the membrane normal. The rotational diffusion coefficient of the lipid molecules was calculated to be Dr = 2.0 x 10(9) rad2.s-1 and the apparent microviscosity in the vesicle membrane, as derived from the rotational correlation time, was eta 2 approximately 12 mPa.s. The rotational correlation time of the phosphate translocator in the membrane was only slightly dependent on the viscosity of the medium. The temperature dependence of the protein rotation also indicated that the rotation of the protein in the membrane was largely restricted and occurred mainly about the axis normal to the membrane plane. Measurements at a medium viscosity of eta 1 = 1 mPa.s yielded a value of phi r approximately 450 ns corresponding to Dr = 8.8 x 10(7) rad2.s-1 for protein rotation with respect to the membrane normal. From this value and the data of the lipid rotation, the cross-sectional area of the protein part embedded in the membrane was calculated to be approximately 9 nm2. This cross-sectional area is large enough to include at most 14 membrane-spanning helices. Our results also indicated that at lipid/protein molar ratios greater than or equal to 1.5 x 10(4): 1 aggregation occurred in the model membranes below 30 degrees C. However, above 30 degrees C and at a high dilution of the protein in the membrane it appeared that the membrane viscosity monitored by lipid and protein rotational diffusion were identical.

Chloroplast Proteins↗