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At least 1,369 records · Page 76Linked to original sources
PubMed1999

Changes and implications of blood flow velocity of the vertebral artery during rotation and extension of the head.

OBJECTIVE: To study the effects of extension and extension-rotation of the head on the blood flow velocity of the vertebral artery experimentally and clinically. DESIGN: Randomized experimental clinical study. SETTING: Institute of Clinical Anatomy and Biomechanics and the Department of Ultrasound, NanFang Hospital of the First Military Medical University, Guangzhou, China. SUBJECTS: The fresh spines from T1-2 to the occipital bone were obtained from persons who died of acute brain death (n = 10). For the transcranial Doppler measurement, 27 asymptomatic subjects with routine physical examination results and 23 students from the above-mentioned university took part in the test. INTERVENTIONS: The instillation experiment in the cadavers was made. Clinical measurements of blood flow velocity in the vertebral artery in the subjects and students were taken and recorded. MAIN OUTCOME MEASURES: Changes in the drop of the vertebral artery were measured by the instillation test in the experimental sample. The blood flow velocity was measured with transcranial Doppler sonography during extension and extension-rotation of the head. RESULTS: During one-sided rotation of the head with extension of the head, measurements in the contralateral vertebral artery and the bilateral vertebral arteries were both reduced in the instillation experiment. The blood flow velocity in the bilateral vertebral arteries decreased during extension and extension-rotation of the head in the subjects and the students. The pulsatility index in the right vertebral arteries increased more than that in the left in extreme extension and that in the bilateral vertebral arteries in neutral position. CONCLUSIONS: Extreme rotation and extension are dangerous to patients who have abnormal vertebral arteries when extreme rotatory and extension manipulations are applied. Doctors should be very careful when rotating the patient's head to the right side.

Adult↗
PubMed1983

Area postrema lesions in rats enhance the magnitude of body rotation-induced conditioned taste aversions.

The role of the area postrema, a circumventricular organ located on the dorsal medulla in the fourth ventricle, in body rotation-induced conditioned taste aversions was examined in male hooded rats. One group of rats received lesions of the area postrema, another group was given sham lesions, and two other groups received no surgery. Three groups of rats, those with area postrema lesions, those with sham lesions, and one unoperated group, were given pairings of 1-hr access to a 0.1% sodium saccharin solution with 30 min of body rotation at 70 rpm (on a schedule of 15-sec on--5-sec off). A fourth group of unoperated rats was given pairings of access to the saccharin solution with 30 min of sham rotation. The three rotated groups all developed a taste aversion to the saccharin solution whereas the sham-rotated group did not. The group with lesions of the area postrema exhibited a greater aversion to the saccharin taste than the other two rotated groups. In a second phase of the experiment all rats were given pairing of 1-hr access to chocolate milk with injections of scopolamine methyl nitrate (1 mg/kg). The area postrema-lesioned group failed to exhibit a taste aversion to the chocolate milk whereas the other groups all showed very strong aversions. It was concluded that area postrema lesions abolish taste aversions induced by blood-borne toxins such as scopolamine methyl nitrate, but enhance taste aversions induced by motion sickness. Some speculations concerning the enhanced taste aversions induced by motion sickness in area postrema lesioned rats, are provided.

Animals↗
PubMed2000

The effect of strength training and reduced training on rotator cuff musculature.

OBJECTIVE: Elucidate the training frequency required to maintain strength gains acquired via short-term resistance training on the rotator cuff. DESIGN: Twenty-one participants performed 12 wk resistance training followed by 12 wk reduced training. Following the training phase (three rotator-cuff-specific exercises; three sessions/wk), participants were randomly assigned to one of three reduced training groups (2, 1 or 0 session(s)/wk). METHODS: Isokinetic testing was done at 0, 6, 12, 18 and 24 wk to obtain mean and peak torque (N m). Testing involved concentric and eccentric actions of internal and external rotation for both shoulders at 60 and 120 degrees /s. RESULTS: Training produced increases in mean and peak torque for all tests but the four of concentric external rotation. A control group performed no training, showing no changes in strength at 0, 6 and 12 wk. Reduced training (2 or 1 session(s)/wk) produced no decreases in peak or mean torque. Detraining (0 session/wk) produced mean torque decreases in four tests, with eccentric strength showing greater losses. CONCLUSIONS: A training frequency of 1 session/wk maintains rotator cuff strength gains in previously untrained subjects. Further, eccentric strength may be more susceptible to detraining. RelevanceThese findings have direct relevance to functional rehabilitation practices for the rotator cuff. They may aid in resistance training programming for athletes during the off-season or returning from injury, particularly those in overhand sports.

Arm↗
PubMed2003

Axial neck rotation strength in neutral and prerotated postures.

OBJECTIVE: To characterize isometric rotation strength in the neutral and in different prerotated positions of the neck. DESIGN: This was a descriptive study involving maximal isometric strength measurements of the cervical musculature. BACKGROUND: The literature contains only a few studies pertaining to strength levels of the neck rotator muscles in the neutral position. None of these studies have dealt in detail with maximal neck strength in selected prerotation positions. METHOD: Twenty healthy men volunteered as subjects. Maximal axial rotation strength of the neck muscles was measured in a neutral position and bilaterally at 30 degrees and 60 degrees rotation using the isometric neck strength measurement system. Isometric maximum voluntary contractions of the neck muscles in flexion and extension were also tested. RESULTS: The highest strength values were not reached in the neutral position, but at the largest joint angles, while turning the head in the opposite direction from the prerotated position. Maximal strength increased with increasing angle, and at the 60 degrees prerotation angle it was 44% higher towards the right and 27% higher towards the left compared to the values obtained in the neutral position. The smallest strength values were also produced at the largest prerotation angles, but in the same direction. CONCLUSIONS: The present results show a clear relationship between the prerotated position of the neck and maximal voluntary strength in rotation. RELEVANCE: The data suggest that neck strength is highly prerotation angle dependent. Neck strength should be measured at several prerotation positions in addition to the neutral position in order to obtain the true strength values throughout the entire range of motion. Maximal neck rotation strength between subjects is differentiated best at the greatest prerotation angles.

Humans↗
PubMed2000

The effect of negative intraarticular pressure and rotator cuff force on glenohumeral translation during simulated active elevation.

OBJECTIVE: The objective of this study was to determine the effect of negative pressure in the intraarticular space and subacromial bursa, as well as rotator cuff force, on glenohumeral translation during active elevation. DESIGN: Glenohumeral translation during elevation in the scapular plane was measured under greater than, less than, and equal to physiologic rotator cuff muscle force, as well as with and without the subacromial bursa and intraarticular space vented. BACKGROUND: Negative intraarticular pressure has been shown to help stabilize the glenohumeral joint in passive motion, although the effect on translation during active motion has not been investigated. METHODS: Eight cadaverous human shoulder specimens were tested in a dynamic shoulder simulator. Forces in the muscles of the rotator as well as the middle deltoid muscle were simulated using servohydraulic cylinders. Joint motion was measured using an ultrasonic motion analysis system. RESULTS: Superior translation of the humerus increased 1.2 mm (SD, 0.4) upon venting of the bursa, and 2.1 mm (SD, 1.7) upon venting of the joint capsule at 25 degrees of glenohumeral elevation in the scapular plane. At 90 degrees elevation, venting the bursa did not change superior translation but increased anterior translation 1.04 mm (SD, 1.0). Venting of the joint capsule increased superior translation by 2.8 mm (SD, 2.5). Decreasing rotator cuff force increased superior translation, while reducing it did not. CONCLUSION: The muscles of the rotator cuff and the negative pressure of the intraarticular space and the subacromial bursa stabilize the glenohumeral joint since they restrict translation in the superior and anterior directions. RelevanceIncreased glenohumeral translation and the resulting asymmetric loading may lead to arthrosis and ultimately rotator cuff arthropathy.

Adult↗
PubMed1998

Topographical organization of inferior olive cells projecting to translation and rotation zones in the vestibulocerebellum of pigeons.

Previous electrophysiological studies in pigeons have shown that the vestibulocerebellum can be divided into two parasagittal zones based on responses to optic flow stimuli. The medial zone responds best to optic flow resulting from self-translation, whereas the lateral zone responds best to optic flow resulting from self-rotation. This information arrives from the retina via a projection from the accessory optic system to the medial column of the inferior olive. In this study we investigated inferior olive projections to translational and rotational zones of the vestibulocerebellum using the retrograde tracer cholera toxin subunit B. Extracellular recordings of Purkinje cell activity (complex spikes) in response to large-field visual stimuli were used to identify the injection sites. We found a distinct segregation of inferior olive cells projecting to translational and rotational zones of the vestibulocerebellum. Translation zone injections resulted in retrogradely labeled cells in the ventrolateral area of the medial column, whereas rotation zone injections resulted in retrogradely labeled cells in the dorsomedial region of the medial column. Motion of any object through space, including self-motion of organisms, can be described with reference to translation and rotation in three-dimensional space. Our results show that, in pigeons, the brainstem visual systems responsible for detecting optic flow are segregated into channels responsible for the analysis of translational and rotational optic flow in the inferior olive, which is only two synapses from the retina.

Animals↗
PubMed1999

Vestibular and vestibulo-proprioceptive perception of motion in the horizontal plane in blindfolded man--II. Estimations of rotations about the earth-vertical axis.

Perception of angular displacement in the horizontal plane was studied in blindfolded human subjects. Subjects sitting on a rotating chair were turned and turned themselves about the earth-vertical axis. Magnitudes of left- and rightward directed rotations were in steps of 30 degrees and overlapped an entire circle. The averaged relative angular error in estimation of passive turns was 0.19 +/- 0.014 (M +/- m), that of active turns 0.16 +/- 0.011. Passively rotated subjects tended to overestimate turns with an increase in the rotation magnitude. Estimations of passive turns were linearly related to the turn magnitude (Y= -0.357+1.065X; R2=0.864). When turning themselves, subjects tended to overestimate rotations of lower magnitudes and underestimate those of higher magnitudes. Linearity was observed between estimations of active turns and their magnitude (Y=26.456+0.862X; R2=0.857). Turn estimation is regarded as a geometrical task, which associates subjectively defined angular and linear parameters of circular motion. It is proposed that during rotation blindfolded subjects perceive the horizontal plane as a heterometric space, the extent of which depends on the estimation of a turn.

Adult↗
PubMed1999

Dopamine agonist-mediated rotation in rats with unilateral nigrostriatal lesions is not dependent on net inhibitions of rate in basal ganglia output nuclei.

Current models of basal ganglia function predict that dopamine agonist-induced motor activation is mediated by decreases in basal ganglia output. This study examines the relationship between dopamine agonist effects on firing rate in basal ganglia output nuclei and rotational behavior in rats with nigrostriatal lesions. Extracellular single-unit activity ipsilateral to the lesion was recorded in awake, locally-anesthetized rats. Separate rats were used for behavioral experiments. Low i.v. doses of D1 agonists (SKF 38393, SKF 81297, SKF 82958) were effective in producing rotation, yet did not change average firing rate in the substantia nigra pars reticulata or entopeduncular nucleus. At these doses, firing rate effects differed from neuron to neuron, and included increases, decreases, and no change. Higher i.v. doses of D1 agonists were effective in causing both rotation and a net decrease in rate of substantia nigra pars reticulata neurons. A low s.c. dose of the D1/D2 agonist apomorphine (0.05 mg/kg) produced both rotation and a robust average decrease in firing rate in the substantia nigra pars reticulata, yet the onset of the net firing rate decrease (at 13-16 min) was greatly delayed compared to the onset of rotation (at 3 min). Immunostaining for the immediate-early gene Fos indicated that a low i.v. dose of SKF 38393 (that produced rotation but not a net decrease in firing rate in basal ganglia output nuclei) induced Fos-like immunoreactivity in the striatum and subthalamic nucleus, suggesting an activation of both inhibitory and excitatory afferents to the substantia nigra and entopeduncular nucleus. In addition, D1 agonist-induced Fos expression in the striatum and subthalamic nucleus was equivalent in freely-moving and awake, locally-anesthetized rats. The results show that decreases in firing rate in basal ganglia output nuclei are not necessary for dopamine agonist-induced motor activation. Motor-activating actions of dopamine agonists may be mediated by firing rate decreases in a small subpopulation of output nucleus neurons, or may be mediated by other features of firing activity besides rate in these nuclei such as oscillatory firing pattern or interneuronal firing synchrony. Also, the results suggest that dopamine receptors in both the striatum and at extrastriatal sites (especially the subthalamic nucleus) are likely to be involved in dopamine agonist influences on firing rates in the substantia nigra pars reticulata and entopeduncular nucleus.

Animals↗
PubMed1995

Rotational stability of the carpus relative to the forearm.

To perform rotational tasks adequately, the rotational laxity between the radius and the carpus must be constrained within a certain limit. The contribution of nine individual capsuloligamentous structures to the rotational stability of the radiocarpal joint was studied using 14 fresh-frozen human cadaveric specimens. Torque-rotation curves, with sequential section of the soft-tissue structures, were used to calculate the percentage contribution of each individual structure. The primary pronation constraint was the palmar radioscaphocapitate ligament. The contributions to supination constraint were more complex; the dorsal radiotriquetral ligament was dominant, assisted by the palmar ulnolunate ligament. Structures originating from the ulna changed their major constraint contribution with forearm orientation, whereas those with a radial origin had a constant contribution independent of forearm rotation. Injury of these structures may lead to rotational instability at the radiocarpal level and should be considered when treating carpal instabilities.

Adult↗
PubMed2001

Rotating reverse osmosis: a dynamic model for flux and rejection.

Reverse osmosis (RO) is a compact process for the removal of ionic and organic pollutants from contaminated water. However, flux decline and rejection deterioration due to concentration polarization and membrane fouling hinders the application of RO technology. In this study, a rotating cylindrical RO membrane is theoretically investigated as a novel method to reduce polarization and fouling. A dynamic model based on RO membrane transport incorporating concentration polarization is used to predict the performance of rotating RO system. Operating parameters such as rotational speed and transmembrane pressure play an important role in determining the flux and rejection in rotating RO. For a given geometry, a rotational speed sufficient to generate Taylor vortices in the annulus is essential to maintain high flux as well as high rejection. The flux and rejection were calculated for wide range of operating pressures and rotational speeds.

Filtration↗
PubMed2002

Design parameters for rotating cylindrical filtration.

Rotating cylindrical filtration displays significantly reduced plugging of filter pores and build-up of a cake layer, but the number and range of parameters that can be adjusted complicates the design of these devices. Twelve individual parameters were investigated experimentally by measuring the build-up of particles on the rotating cylindrical filter after a fixed time of operation. The build-up of particles on the filter depends on the rotational speed, the radial filtrate flow, the particle size and the gap width. Other parameters, such as suspension concentration and total flow rate are less important. Of the four mechanisms present in rotating filters to reduce pore plugging and cake build-up, axial shear, rotational shear, centrifugal sedimentation and vortical motion, the evidence suggests rotational shear is the dominant mechanism, although the other mechanisms still play minor roles. The ratio of the shear force acting parallel to the filter surface on a particle to the Stokes drag acting normal to the filter surface on the particle due to the difference between particle motion and filtrate flow can be used as a non-dimensional parameter that predicts the degree of particle build-up on the filter surface for a wide variety of filtration conditions.

Biomechanical Phenomena↗
PubMed1999

Effects of eye rotation on the sound-evoked post-auricular muscle response (PAMR).

One objective electrophysiological test for deafness involves presenting a brief acoustic stimulus to a subject and measuring the electrical activity evoked in the muscle located just behind the ear (the post-auricular muscle or PAM). We describe a method for enhancing this post-auricular muscle response (PAMR) using lateral eye movement, which increases both the tonic EMG activity in the PAM and the magnitude of the PAMR, and decreases response latency. EMG activity in most subjects tested (more than 30) increased almost instantly on rotation of the eyes, and thereafter grew more slowly with maintained lateral gaze, with the largest increase occurring with eye rotation towards rather than away from the measurement electrodes over the PAM. The EMG activity returned rapidly to near pre-rotation levels when the eyes were returned to the forwards position, with full recovery taking some minutes. While there was a similar increase and return of the PAMR amplitude with eye rotation, the time-course of these changes was somewhat different, largely because the EMG activity and the PAMR amplitude were not proportional. Rather the PAMR amplitude was a saturating function of EMG level, so that the PAMR response did not fall as markedly as the EMG when the eyes were returned to a forwards gaze, and the recovery of the PAMR amplitude to pre-rotation levels appeared to take longer. We discuss the neural mechanisms that may be responsible for this PAMR potentiation with eye movement and discuss its probable role in increasing variability in early studies which did not control for eye movement. We also discuss the utility of eye rotation in potentiating and stabilising the PAMR to allow its use in screening for deafness.

Acoustic Stimulation↗
PubMed2002

EMG activity of trunk muscles and torque output during isometric axial rotation exertion: a comparison between back pain patients and matched controls.

Abnormal patterns of trunk muscle activity could affect the biomechanics of spinal movements and result in back pain. The present study aimed to examine electromyographic (EMG) activity of abdominal and back muscles as well as triaxial torque output during isometric axial rotation at different exertion levels in back pain patients and matched controls. Twelve back pain patients and 12 matched controls performed isometric right and left axial rotation at 100%, 70%, 50% and 30% maximum voluntary contractions in a standing position. Surface EMG activity of rectus abdominis, external oblique, internal oblique, latissimus dorsi, iliocostalis lumborum and multifidus were recorded bilaterally. The primary torque in the transverse plane and the coupling torques in sagittal and coronal planes were measured. Results showed that there was a trend (P = 0.08) of higher flexion coupling torque during left axial rotation exertion in back pain patients. Higher activity for external oblique and lower activity for multifidus was shown during left axial rotation exertion in back pain group when compared to the control group. In right axial rotation, back pain patients exhibited lesser activity of rectus abdominis at higher levels of exertion when compared with matched controls. These findings demonstrated that decreased activation of one muscle may be compensated by overactivity in other muscles. The reduced levels of activity of the multifidus muscle during axial rotation exertion in back pain patients may indicate that spinal stability could be compromised. Future studies should consider these alternations in recruitment patterns in terms of spinal stability and internal loading. The findings also indicate the importance of training for coordination besides the strengthening of trunk muscles during rehabilitation process.

Abdominal Muscles↗
PubMed1996

Effect of medial displacement of the tibial tubercle on patellar position after rotational malposition of the femoral component in total knee arthroplasty.

A large Q angle induced by technical error such as an internally rotated femoral component causes patellar failure after total knee arthroplasty. The effect of medial displacement of the tibial tubercle to decrease the Q angle for patellar tracking was studied by evaluating the patellar position relative to the patellar groove on the femoral component in cadaver specimens. A 5 degrees internally rotated femoral component caused the patella to shift medially about 5 mm, and also caused the tibia to rotate internally about 3 degrees at full extension. With a 5 degrees externally rotated femoral component, normal patellar tracking occurred. The distance of medial displacement was determined so that the patellar tendon was parallel to the longitudinal axis of the tibia at full extension. This allowed the quadriceps tendon, the patella, and the patellar tendon to form a straight line. The average distance of medial transposition of the tibial tubercle was 9.32 mm. Medialization of the tibial tubercle caused the patella to shift about 2 mm medially from the patellar groove. The transfer also caused an external rotation of the tibia (2 degrees-5 degrees). Medial transfer of the tibial tubercle changes patellar kinematics and corrects the tendency toward lateral patellar dislocation caused by internally rotating the femoral component; however, it also creates minor patellar and tibial kinematic changes that may have a clinical effect.

Biomechanical Phenomena↗
PubMed2003

Early rotational stability of the longer Staar toric intraocular lens: fifty consecutive cases.

PURPOSE: To determine whether rotational stability is improved with the longer Staar toric intraocular lens (IOL). SETTING: A private practice, Los Altos, California, USA. METHODS: Staar Surgical manufactures toric plate-haptic IOLs under +24.0 diopters (D) in 2 lengths. Fifty consecutive eyes requiring toric IOL spherical powers less than +24.0 D received the longer toric IOL (TL; 11.2 mm) using a specific surgical protocol. The IOL axis was recorded at 1 day, 1 week, and a final follow-up visit. Five additional eyes requiring powers greater than +24.0 D received the shorter toric IOL (TF; 10.8 mm), which is the only available length in these powers. Results were compared with those in an initial consecutive series of 6 eyes having implantation of the TF IOL with a power less than +24.0 D before the TL model became available. RESULTS: Rotational stability of all 50 TL IOLs and the 5 TF IOLs of higher dioptric powers was excellent. One IOL rotated as much as 20 degrees off axis. The repositioning rate was zero in both groups. In the initial 6 eyes receiving the shorter toric IOL in powers below +24.0 D, the repositioning rate was 50%. CONCLUSIONS: The longer toric IOL had excellent early rotational stability. Rotational and repositioning rates with the TL IOL were superior to those in a previous series of the TF IOL. Adequate overall length is a critical factor in the rotational stability of plate-haptic toric IOLs, and the longer IOL should be used when available.

Adult↗
PubMed1998

Codman's paradox of the arm rotations is not a paradox: mathematical validation.

Movement of a straight arm centred at the shoulder joint in three successive 90 degrees rotations, each around the respective orthogonal coordinate axis, leads to an apparently unrelated 90 degrees rotation around the longitudinal arm axis. This empirical fact is known as Codman's paradox, after a Bostonian surgeon who first reported it in 1934. However, by means of homogeneous coordinates, it is herein demonstrated that the phenomenon is just a mechanical property mathematically described by the equivalence between the matricial product of three orthogonal rotation matrices applied to a position vector and the matricial product of a single rotation matrix applied to the same vector. The latter rotation matrix corresponds to the middle one in the former group of three. When polar coordinates are used, the demonstration is even simpler, for the total shift vector clearly shows a single net effect on the longitudinal axis rotation. Thus, Codman's paradox is not a paradox. This property improves the muscle dynamics arm knowledge and might find applications in robotics.

Arm↗
PubMed1991

Microsecond rotational dynamics of spin-labeled Ca-ATPase during enzymatic cycling initiated by photolysis of caged ATP.

We have measured the microsecond rotational motions of the sarcoplasmic reticulum (SR) Ca-ATPase as a function of enzyme-specific ligands, including those that induce active calcium transport. We labeled the Ca-ATPase with a maleimide spin probe and detected rotational dynamics using saturation-transfer electron paramagnetic resonance (ST-EPR). This probe's ST-EPR spectra have been shown to be sensitive to microsecond protein rotational motion, corresponding to large-scale protein rotations that should be affected by changes in the enzyme's shape, flexibility, protein-protein interactions (oligomeric state), and protein-lipid interactions. We found that the motions of the enzyme-nucleotide and the enzyme-nucleotide/Ca states are indistinguishable from the motions in the absence of ligands. Rotational mobility does decrease in response to the addition of DMSO, a solvent that inhibits Ca-ATPase activity and stabilizes the phosphoenzyme. However, the addition of phosphate to form phosphoenzyme, in the presence or absence of DMSO, does not change the motions significantly. During the steady state of active calcium transport, the microsecond rotational mobility is indistinguishable from that of the resting enzyme. In order to detect any transient changes in mobility that might not be detectable in the steady state and to improve the precision of steady-state measurements, we photolyzed caged ATP with a laser pulse in the presence of calcium and detected the ST-EPR response from the spin-labeled enzyme, with a time resolution of 1 s.(ABSTRACT TRUNCATED AT 250 WORDS)

Adenosine Triphosphate↗
PubMed1989

Fluorescence depolarization of cis- and trans-parinaric acids in artificial and red cell membranes resolved by a double hindered rotational model.

Although steady-state anisotropy measurements of phase-sensitive probes provide a qualitative description of the phase behavior of biomembranes, there is little information about the physical state of lipid domains. We have developed a ground-state double hindered rotator model (DHR) for fluorescence anisotropy decay, in which probes possess separate rotational correlation times and r infinity in each phase. To validate the model, multifrequency differential phase angles (delta) and modulation amplitudes (lambda) were measured in a two-compartment cuvette with combinations of POPOP, TMA-DPH, and DPH in isotropic solvents and in DPPC liposomes. Rotational parameters obtained by fitting the DHR model were similar to those of a single hindered rotator model fitted to data obtained separately for each probe. As predicted by the model, negative delta and decreasing lambda with increasing modulation frequency were obtained when fluorophores in isotropic solvents were paired with fluorophores in DPPC liposomes. The rotational parameters of the phase-sensitive fluorophores cis-parinaric (cPnA) and trans-parinaric (tPnA) acid in DPPC/DMPC (1:0, 0:1, and 1:1) liposomes were determined at 15-40 degrees C. Two lifetimes (1 and 3 ns) were obtained above the phase transition temperature (Tc); greater than 95% of the fluorescence intensity was described by two lifetimes (3-9 and 12-32 ns) below Tc. Negative delta values were obtained when solid-phase lipid was present. r infinity varied from 0.26-0.32 below to 0.11-0.14 above Tc; at intermediate T, where two phases coexists, r infinity values were approximately 0.23 and approximately 0.31. These data indicate very hindered PnA rotation in solid-phase lipid.(ABSTRACT TRUNCATED AT 250 WORDS)

1,2-Dipalmitoylphosphatidylcholine↗