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PubMed2002

Mental rotation of tactile stimuli.

When subjects decide whether two visual stimuli presented in various orientations are identical or mirror-images, reaction time increases with the angular disparity between the stimuli. The interpretation of this well-known observation is that subjects mentally rotate images of the stimuli until they are in congruence, in order to solve the task. Here we review studies involving mental rotation of tactile stimuli. Mental rotation in tactile tasks is specifically associated with the requirement for mirror-image discrimination, as opposed to identity judgments. The key brain region mediating mental rotation of tactile stimuli seems to be the parietal cortex. Visual processing appears to facilitate task performance. We report an experiment from our laboratory addressing the nature of the reference frame for mental rotation of tactile stimuli. Our observations indicate that when the hand is directly in front of the body, with the head facing forward, the shortest reaction times for mirror-image discrimination of stimuli applied to the fingerpad are obtained when the longitudinal axis of the stimulus is in or parallel to the sagittal plane, even when this is perpendicular to the long axis of the finger. Thus, the reference frame for mental rotation of tactile stimuli is not purely hand-centered. This is consistent with other findings indicating variable assignment of reference frames for tactile perception.

Animals↗
PubMed2002

The application of dynamic field shaping and dynamic dose rate control in conformal rotational treatment of the prostate.

The current philosophy of dose escalation in the treatment of prostate cancer has forced the treatment planner to re-evaluate his/her planning approach. Precise and accurate delivery of dose to the prostate while maintaining the required dose limits to the normal critical structures, such as the rectum, has become increasingly difficult in light of these escalated doses. Conformal treatment techniques allow the treatment planner to precisely shape each individual treatment field so that desired volume coverage and normal tissue sparing can be achieved. In addition to these beam-shaping advantages, adjustment of an individual beam's weighting also helps to create the desired distribution and tissue sparing. Rotational therapy "simulates" treatment with multiple beams and angles, similar to the thought process behind conformal treatment technique. With rotational therapy, however, the treatment planner's inability to provide adequate beam shaping and weighting adjustment has placed limits on its value as a viable planning option. The introduction of computer-controlled treatment machines, which allow dynamic adjustment of the field shape with the rotation of the beam, makes it possible to re-evaluate rotational therapy as a potential option. Similarly, the treatment planner's ability to change field weighting can be accomplished by the application of dynamic dose rate control, allowing a rotational beam to deliver a weighting similar to that possible with conformal fixed-field techniques. Dose-volume histogram data will be used to evaluate doses delivered to the prostate, rectum, and bladder using rotational therapy with dynamic field shape and dynamic dose rate control as a treatment planning option. The dose delivery and normal tissue-sparing potential of this technique compared to coplanar and noncoplanar conformal fixed-field techniques will also be presented.

Femur Head↗
PubMed2003

EGF signaling and ommatidial rotation in the Drosophila eye.

The ommatidia of the Drosophila eye initiate development by stepwise recruitment of photoreceptors into symmetric ommatidial clusters. As they mature, the clusters become asymmetric, adopting opposite chirality on either side of the dorsoventral midline and rotating exactly 90 degrees (Figures 1A and 1B, ). The choice of chirality is governed by higher activity of the frizzled (fz) gene in one cell of the R3/R4 photoreceptor pair and by Notch-Delta (N-Dl) signaling. The 90 degrees rotation also requires activity of planar polarity genes such as fz as well as the roulette (rlt) locus. We now show that two regulators of EGF signaling, argos and sprouty (sty), and a gain-of-function Ras85D allele, interact genetically with fz in ommatidial polarity. Furthermore, we find that argos is required for ommatidial rotation, but not chirality, and that rlt is a novel allele of argos. We present evidence that there are two pathways by which EGF signaling affects ommatidial rotation. In the first, typified by the rlt phenotype, there is partial transformation of the "mystery cells" toward a neuronal fate. Although most of these mystery cells subsequently fail to develop as neurons, their partial transformation results in inappropriate subcellular localization of the Fz receptor, a likely cue for regulating ommatidial rotation. Secondly, reducing EGF signaling can specifically affect ommatidial rotation without showing transformation of the mystery cells or defects in polarity protein localization.

Animals↗
PubMed2001

Comparison between a Constrained Condylar and a Rotating Hinge in revision knee surgery.

The performance of Constrained Condylar and Rotating Hinge types of total knee replacement was compared by mechanical testing, by using the Knee Society Clinical and Radiographic evaluations, and by a self-assessment questionnaire. In mechanical tests to evaluate varus strength, Constrained Condylars developed at least 6 degrees of varus rotation, but there was minimal varus rotation in the Rotating Hinges. This was reflected in the stability scores in the Knee Society evaluation. The shorter stems used in the Constrained Condylars resulted in a higher variation in femoral-tibial angles, and a smaller than ideal valgus angle. Radiographically, the only radiolucent lines observed were those adjacent to the joint itself, and there was no difference between the two types of total knee replacement. From the questionnaire, there was a high correlation in the performances between the operated and non-operated knees in the Rotating Hinge group. This indicated the Hinges were capable of matching their performance to a required level, thereby producing a better overall clinical result. In summary, the study indicated that a Rotating Hinge type should be given greater consideration, particularly if the disadvantages of larger bone resection and longer stems could be overcome.

Arthroplasty, Replacement, Knee↗
PubMedDate not supplied

Rotator interval lesions and their relation to coracoid impingement syndrome.

In the last 10 years we have found impingement of the coracoid process on the rotator interval in 12 patients (14 shoulders). Seven of these patients were women and 5 were men; the average patient age was 48.5 years. One patient had a calcified coracohumeral ligament, another patient had an anterior tear of a repaired deltoid flap, and a third had an aberrant pectoralis minor tendon inserted into the rotator interval. Eleven patients had a weak rotator interval, and in 4 cases the rotator interval had a small tear. We closed the rotator interval in all 12 patients. We also performed a coracoidoplasty in 5 of the patients. The condition of all shoulders improved clinically after operation; the average follow-up was 4.2 years. Three patients (4 shoulders) still had moderate pain, and 7 patients (9 shoulders) lacked strength. Internal rotation was the only shoulder movement that remained limited. Although impingement seemed obvious during surgery, experimental studies have reported contradictory findings.

Acromion↗
PubMed1998

Transverse arrest: a review of outcomes of rotational forceps and cesarean delivery at a single center.

Objective: To assess whether Kielland forceps rotational delivery causes a significant increase in maternal or perinatal morbidity in comparison with cesarean delivery in the clinical situation of transverse arrest. Rotational forceps delivery has been reported to have unacceptably high maternal and neonatal complication rates when compared with either spontaneous vaginal delivery or non-rotational forceps delivery. Clinically, however, we considered the more relevant comparison between Kielland rotational forceps delivery and cesarean delivery as these are generally the two modes of delivery for the fetus in transverse arrest.Study Design: The charts of all the mothers delivered by Kielland forceps or cesarean delivery for the main indication of transverse arrest between July 1995 and June 1996 were reviewed. The following were evaluated: Apgar scores at 1 and 5 minutes, cord pH, birth weight, neonatal superficial facial laceration or bruising, bone or nerve injuries, maternal injuries, 3rd and 4th degree perineal or vaginal lacerations, post-partum fever. Statistical analysis was by chi(2) (for Apgar scores), two-tailed Fisher Exact test (for post-partum fever), and t test (for birth weight and cord pH). A P value <.05 was considered statistically significant.Results: Fifty-two Kielland forceps and 30 cesarean deliveries were performed. One-minute Apgar scores of less than or equal to 7 were noted in 11.5% and 6.7% of the forceps and cesarean section groups, respectively (P = NS); mean arterial cord pH was 7.26 for both groups; no cases of post-partum fever were noted in the forceps versus 16% in the cesarean group (P <.05); the mean weight was 3,316 and 3,569 g for the forceps and cesarean group, respectively (P <.05). The Kielland group was also characterized by the following: 19 facial bruising and 2 temporary facial nerve injury (resolved by the time of discharge), 3 perineal lacerations, and 3 vaginal tears. No blood transfusions were required for either group.Conclusions: To our knowledge, this is the first study that compares rotational forceps delivery for transverse arrest with its true clinical alternative, cesarean delivery.No significant difference in cord pH and Apgar scores were noted between the two groups. The birth weight was greater and post-partum fever was more common in the cesarean section group. Neonatal facial bruising, temporary facial nerve palsy, and maternal perineal and vaginal lacerations were more common in the forceps groups. This study suggests that rotational forceps may be a reasonable alternative to cesarean delivery in the management of transverse arrest.

Journal Article↗
PubMed2000

Correlation between radiology resident rotation performance and examination scores.

RATIONALE AND OBJECTIVES: The authors' purpose was to determine whether there is a relationship between subjective assessment of radiology resident performance on individual rotations and objective assessment of radiology resident performance on the American College of Radiology (ACR) in-training and American Board of Radiology (ABR) written examinations. MATERIALS AND METHODS: Records of 81 radiology residents completing their residency between 1991 and 2000 were reviewed. Mean scores from all rotation evaluation forms obtained during the study period were calculated for each residency year. The means of the overall raw scores and percentiles obtained on the annual ACR in-training examinations during the first 3 years of residency and of the written portion of the ABR examination taken during the 4th year of residency were also determined. Rotation evaluation scores were then compared to examination scores obtained during the same year of residency, and correlation coefficients were obtained. RESULTS: In the 2nd, 3rd, and 4th years of radiology residency, there is positive correlation between rotation evaluation scores and overall scores from the corresponding ACR in-training examination and written portion of the ABR examination taken during the same year. In contrast, in the 1st year of residency, resident rotation evaluation scores do not correlate with ACR in-training examination scores. CONCLUSION: Residents who are perceived as doing well on their rotations after the 1st year of residency are more likely to do well on standardized written examinations.

Analysis of Variance↗
PubMedDate not supplied

Improved AMBER torsional parameters for the N-N rotational barrier in diacylhydrazines.

The structure and rotational barrier for substituted diacylhydrazines are of significant interest given the role this functionality plays in peptidomimetics and ecdysone agonists, the latter of which have application as extremely selective insecticides. Ab initio calculations show that the lowest energy conformations are typically nonplanar with essentially perpendicular nitrogen lone pairs. Molecular mechanics calculations using the AMBER force field in MacroModel yield minima and rotational barriers that are both quantitatively and qualitatively inconsistent with the ab initio results. In this work the AMBER N-N rotational barriers for all configurations of the parent, methyl and di-methyl substituted diformylhydrazines have been fitted to MP2/6-31 + G relative energies. The resulting AMBER torsional parameters have been validated by calculating the rotational barriers for N-t-butyl substituted diformylhydrazine, dibenzoylhydrazine and an azadipeptide. In each case the new AMBER rotational barriers compare favorably with the corresponding MP2 calculated rotational barriers.

Ecdysone↗
PubMed2002

Opioid rotation in the treatment of joint pain. A review of 67 cases.

OBJECTIVE: To determine that opioid rotation can be useful for establishing a more advantageous analgesia/toxicity relationship in rheumatologic pain. METHODS: Among patients treated with opioids for rheumatologic non-malignant pain, 67 patients with opioid rotation were enrolled retrospectively. In all cases, the other analgesics had failed. The opioids used were: oral morphine, oral hydromorphone, oral buprenorphine and transdermal fentanyl. The reasons for rotation were noted and the improvement of pain was assessed by comparing baseline and post-treatment visual analog scales (VAS in mm). RESULTS: The 67 patients suffered from low back pain with sciatica in 27 cases, inflammatory arthritis in 14 cases, brachial neuralgia in six cases, osteoarthritis in eight cases and miscellaneous in 12 cases. The opioid rotations were the substitution of morphine by transdermal fentanyl, by oral hydromorphone in most of the cases. The principal reason for opioid rotation was failure of the first treatment. The mean of VAS improvement was 30 mm (P < 0.001). CONCLUSION: In rheumatologic non-malignant pain, the opioid rotation might allow the physician to bypass side effects or failure to alleviate pain in most cases.

Administration, Cutaneous↗
PubMed1999

On separating processes of event categorization, task preparation, and mental rotation proper in a handedness recognition task.

We investigated the nature of event-related potential (ERP) effects in a handedness recognition task requiring mental rotation. Thirty subjects were tested with rotated and sometimes reflected alphanumeric characters while ERPs were recorded from 18 electrodes. On each trial, a cue provided valid information about the angular displacement of the following probe. This design allowed a distinction between three processing episodes: evaluation of the difficulty of the forthcoming task, preparation for the task, and the mental rotation task itself. The three episodes were accompanied by distinct ERP effects having distinct polarities, a different rank order of amplitudes for different probe orientations, and a different topography. These data confirm previous findings showing that mental rotation is accompanied by a parietal negativity. However, they also suggest that the rotation-related negativity found after tilted stimuli in standard mental rotation tasks is most likely overlapping with another, simultaneously triggered ERP effect functionally related to an evaluation of task difficulty.

Adult↗
PubMed2001

Rotating electrode potentiometry: lowering the detection limits of nonequilibrium polyion-sensitive membrane electrodes.

A rotating electrode configuration is evaluated as a means to lower the detection limits of newly devised polyion-sensitive membrane electrodes (PSEs). Planar potentiometric polycation and polyanion PSEs are prepared by incorporating tridodecylmethylammonium chloride and calcium dinonylnaphthalenesulfonate, respectively, into plasticized PVC or polyurethane membranes and mounting disks of such films on an electrode body housed in a conventional rotating disk electrode apparatus. Rotation of the PSEs at 5000 rpm results in an enhancement in the detection limits toward heparin (polyanion) and protamine (polycation) of at least 1 order of magnitude (to 0.01 unit/mL for heparin; 0.02 microg/mL for protamine) over that observed when the EMF responses of the same electrodes are assessed using a stir-bar to achieve convective mass transport. A linear relationship between omega(-1/2), where omega is the rotating angular frequency, and C1/2, the polyion concentration corresponding to half the total maximum deltaEMF response toward the polyion species, is observed. It is further shown that the rotating polycation sensor can be used as an end-point detector to greatly enhance (relative to nonrotated indicator electrode) the analytical resolution and precision for measurement of low concentrations of heparin when such samples are titrated with protamine. The theoretical basis for lowering the detection limits by rotating PSEs is discussed based on the unique nonequilibrium response mechanism of such sensors.

Electrodes↗
PubMed2004

Online CE-MALDI-TOF MS using a rotating ball interface.

We report on the construction and performance of a rotating ball interface for online coupling of capillary electrophoresis (CE) to matrix-assisted laser desorption ionization (MALDI) mass spectrometry with a time-of-flight (TOF) mass analyzer. The interface is based on a rotating stainless steel ball that transports samples from atmospheric pressure to the high vacuum of the mass spectrometer for desorption and ionization. The sample is deposited directly from a 50-microm-i.d. separation capillary onto the 19-mm ball that is rotating at 0.03 to 0.3 rpm. The sample is mixed online with matrix flowing from a separate 50-microm-i.d. capillary. The sample deposit dries before it is rotated past a polymer gasket and into the laser ionization region. Cleaning of the interface is accomplished using solvent-saturated felt, which cleans the ball surface after it rotates out of the ionization chamber. On-line CE-MALDI is demonstrated, and the performance is evaluated with the analysis of a mixture of three peptides: [Lsy8] vasopressin, substance P, and neurotensin. The rotating ball interface to MALDI-TOF MS demonstrated mass detection limit in the high femtomole range. The interface has negligible memory effect and shows no significant electrophoretic peak broadening when operated under optimized conditions.

Electrochemistry↗
PubMed1993

Protein and lipid rotational dynamics in cardiac and skeletal sarcoplasmic reticulum detected by EPR and phosphorescence anisotropy.

We have used time-resolved phosphorescence anisotropy and electron paramagnetic resonance (EPR) spectroscopy to detect the rotational dynamics of the Ca-ATPase and its associated lipids in dog cardiac sarcoplasmic reticulum (DCSR), in comparison with rabbit skeletal SR (RSSR), in order to obtain insight into the physical bases for different activities and regulation in the two systems. Protein rotational motions were studied with time-resolved phosphorescence anisotropy (TPA) of erythrosin isothiocyanate (ERITC) and saturation-transfer EPR (ST-EPR) of a maleimide spin-label (MSL). Both labels were attached selectively and rigidly to the Ca-ATPase. Lipid rotational motions were studied with conventional EPR of stearic acid spin-labels. As in previous studies on RSSR, the phosphorescence anisotropy decays of both preparations at 4 degrees C were multiexponential, due to the presence of different oligomeric species. The rotational correlation times for the different rotating species were similar for the two preparations, but the total decay amplitude was substantially less for cardiac SR, indicating that more of the Ca-ATPase molecules are in large aggregates in DCSR. ST-EPR spectra confirmed that the Ca-ATPase is less rotationally mobile in DCSR than in RSSR. Lipid probe mobility and fatty acid composition were very similar in the two preparations, indicating that the large differences observed in protein mobility are not due to differences in lipid fluidity. We conclude that the higher restriction in protein mobility observed by both ST-EPR and TPA is due to more extensive protein-protein interactions in DCSR than in RSSR.

Animals↗
PubMed1992

Rotational motion of monomeric and dimeric immunoglobulin E-receptor complexes.

Erythrosin 5'-thiosemicarbazide labeled immunoglobulin E (IgE) was used to monitor the rotational dynamics of monomeric and dimeric Fc epsilon RI receptors for IgE on rat basophilic leukemia (RBL) basophilic leukemia (RBL) cells using time-resolved phosphorescence anisotropy. Receptors were studied both on living RBL cells and on membrane vesicles derived from RBL cell plasma membrane. The un-cross-linked IgE-receptor complexes on cells and vesicles exhibit rotational correlation times that are consistent with those expected for freely rotating monomers, but a small fraction of these complexes on cells may be rotationally immobile. A comparison of the initial phosphorescence anisotropy values for erythrosin-labeled IgE-receptor complexes on cells and vesicles reveals a fast component of rotational motion that is greater on the vesicles and may be due to a site of segmental flexibility in the receptor itself. Dimers of IgE-receptor complexes formed with anti-IgE monoclonal antibodies appear to be largely immobile on cells, but they are mobile on vesicles with a 2-fold larger rotational correlation time than the monomeric complexes. The results suggest that dimeric IgE-receptor complexes undergo interactions with other membrane components on intact cells that do not occur on the membrane vesicles. The possible significance of these interactions to receptor function is discussed.

Animals↗
PubMed1982

Models for slow anisotropic rotational diffusion in saturation transfer electron paramagnetic resonance at 9 and 35 GHz.

Model systems of cholestane and 5-doxylstearic acid analogue spin probes in lipid bilayer dispersions of dipalmitoylphosphatidylcholine and cholesterol (9:1 w/w) are used to analyze saturation transfer electron paramagnetic resonance spectral behavior for slow rotational diffusion in an anisotropic medium. Measurements are made at both 9 and 35 GHz to provide enhanced spectral resolution for different types of motion. Parameter correlation plots of spectral parameters from different regions of the saturation transfer spectra appear to be potentially useful in characterizing different types of motion. Anisotropic rotational diffusion about a symmetry axis coincident with the nitroxide y principal axis is clearly distinguishable from isotropic rotational diffusion and may be distinguishable from rotational diffusion about the nitroxide z principal axis. Approximate anisotropic rotational diffusion about a symmetry axis coincident with the nitroxide z principal axis is distinguishable from isotropic rotational diffusion under some, but not all, conditions.

Cholestanes↗
PubMed1988

Rotational dynamics of the single tryptophan of porcine pancreatic phospholipase A2, its zymogen, and an enzyme/micelle complex. A steady-state and time-resolved anisotropy study.

The rotational dynamics of the single tryptophan of porcine pancreatic phospholipase A2 and its zymogen (prophospholipase A2) have been studied by polarized fluorescence using steady-state and time-resolved single-photon counting techniques. The motion of Trp-3 in phospholipase A2 consists of a rapid subnanosecond wobble of the indole ring with an amplitude of about +/- 20 degrees accompanied by slower isotropic rotation of the entire protein. The rotational correlation times for overall particle rotational diffusion are consistent with conventional hydrodynamic theory. When phospholipase A2 binds to micelles of n-hexadecylphosphocholine, the amplitude of the fast ring rotation decreases. The whole particle rotational correlation time of the enzyme/micelle complex is smaller than the minimum value calculated from hydrodynamic theory. A similar result is obtained for the micelle itself by using the lipophilic probe transparinaric acid. These low values for the particle correlation times can be understood by postulating that an isotropic motion of the fluorophore in the small detergent particles contributes to the angular reorientation of the fluorophore. The internal reorientational motion of the tryptophan in the zymogen, prophospholipase A2, is of larger amplitude than that observed for the enzyme; specifically, the proenzyme exhibits a motion with a significant amplitude on the nanosecond time scale. This additional freedom of motion is attributed to segmental mobility of the N-terminal residues of prophospholipase A2. This demonstrates that this region of the protein is flexible in the zymogen but not in the processed enzyme. The implications of these findings for the mechanism of surface activation of phospholipase A2 are discussed by analogy with a trypsinogen-trypsin activation model.

Animals↗
PubMed1990

Rotational dynamics of chloroplast ATP synthase in phospholipid vesicles.

The rotational dynamics of the purified dicyclohexylcarbodiimide-sensitive H(+)-ATPase (DSA) reconstituted into phospholipid vesicles and of the DSA coreconstituted with the proton pump bacterio-rhodopsin were examined by using the technique of time-resolved phosphorescence emission anisotrophy. The phosphorescent probe erythrosin isothiocyanate was used to covalently label the gamma-polypeptide of DSA before reconstitution. Rotational correlation times were measured under a variety of conditions. The rotational correlation time was independent of the viscosity of the external medium but increased significantly as the microviscosity of the membrane increased. This indicates the rotational correlation times are a measure of the enzyme motion within the membrane. The activation energy associated with the rotational correlation time is 8-10 kcal/mol. At 4 degrees C, the correlation time, typically approximately 100-180 microseconds, was unaffected by the addition of substrates and the presence of a membrane pH gradient. Therefore, molecular rotation of the DSA does not appear to play an important role in enzyme catalysis or ion pumping.

Chloroplasts↗
PubMed1990

Rotational diffusion of a steroid molecule in phosphatidylcholine-cholesterol membranes: fluid-phase microimmiscibility in unsaturated phosphatidylcholine-cholesterol membranes.

Rotational diffusion of androstane spin-label (ASL), a sterol analogue, in various phosphatidylcholine (PC)-cholesterol membranes was systematically studied by computer simulation of steady-state ESR spectra as a function of the chain length and unsaturation of the alkyl chains, cholesterol mole fraction, and temperature for a better understanding of phospholipid-cholesterol and cholesterol-cholesterol interactions. Special attention was paid to the differences in the cholesterol effects on ASL motion between saturated and unsaturated PC membranes. ASL motion in the membrane was treated as Brownian rotational diffusion of a rigid rod within the confines of a cone imposed by the membrane environment. The wobbling rotational diffusion constant of the long axis, its activation energy, and the cone angle of the confines were obtained for various PC-cholesterol membranes in the liquid-crystalline phase. Cholesterol decreases both the cone angle and the wobbling rotational diffusion constant for ASL in all PC membranes studied in this work. The cholesterol effects are the largest in DMPC membranes. An increase of cholesterol mole fraction from 0 to 30% decreases the rotational diffusion constant by a factor of 9-15 (depending on temperature) and the cone angle by a factor of about 2. In dioleoyl-PC membranes, addition of 30 mol % cholesterol reduces both the rotational diffusion constant and the cone angle of ASL by factors of approximately 2.5 and approximately 1.3, respectively, while it was previously found to cause only modest effects on the motional freedom of phospholipid analogue spin probes [Kusumi, A., Subczynski, W. K., Pasenkiewicz-Gierula, M., Hyde, J. S., & Merkle, H. (1986) Biochim. Biophys. Acta 854, 307-317]. It is proposed that fluid-phase microimmiscibility takes place in dioleoyl-PC-cholesterol membranes at physiological temperatures, which induces cholesterol-rich domains in the membrane, partially due to the steric nonconformability between the rigid fused-ring structure of cholesterol and the 30 degrees bend at the C9-C10 cis double bond of the alkyl chains of dioleoyl-PC. The mechanism by which cholesterol influences the lipid dynamics in the membrane is different between saturated and unsaturated PC membranes.

Cholesterol↗