Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “Rotation”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 1,675 records · Page 93Linked to original sources
PubMed1975

Vectorcardiograms in severe aortic insufficiency. Clockwise rotation of QRS loop in the horizontal plane.

In La Paz Hospital, Madrid, recently, vectorcardiograms (VCGs) were performed on 74 patients with aortic insufficiency. These cases presenting electrocardiographic and radiologic signs of left ventricular hypertrophy, were divided into three groups. In 25 patients (Group 1) the QRS loop in the horizontal plane (HP) showed counterclockwise rotation; 43 patients (Group 2) showed clockwise rotation; and 6 patients (Group 3) showed a pattern of left bundle branch block (LBBB). In Group 2, 31 of the 43 patients (group 2-A) had a Qloop of normal orientation and generally increased voltage, and in the remaining 12 patients (group 2-B) the Q loop was absent. All of the patients in Group 2 had severe aortic insufficiency. Thus, that group's valuation of the left ventricular hypertrophy using maximum QRS vector voltage in the HP, was higher than in Group 1 mean 3.75mV in Group 2 versus mean 2.71mV in Group 1 (p less than 0.01). Postoperative VCGs were performed in 12 patients of group 2-A, showing in all of them a clockwise to counterclockwise rotation change of the QRS loop in the HP. On the other hand, this fact was observed in only two of the eight patients in group 2-B. The clockwise rotation of the QRS loop in the HP is an important datum in our report, particularly in the diagnosis of severe aortic insufficiency. Conversely, a clockwise to counterclockwise rotation change would be a positive sign of good post operative evolution. Finally, two reasons are given to explain this anomalous rotation in the horizontal plane: dilatation and fibrosis.

Adolescent↗
PubMed2002

The effect of antibiotic rotation on colonization with antibiotic-resistant bacilli in a neonatal intensive care unit.

OBJECTIVE: This study was designed to test whether rotation of antibiotics can reduce colonization with resistant Gram-negative bacilli in a neonatal intensive care unit (NICU). METHODS: A monthly rotation of gentamicin, piperacillin-tazobactam, and ceftazidime was compared with unrestricted antibiotic use in side-by-side NICU populations (rotation team vs control team). Pharyngeal and rectal samples were obtained 3 times a week and tested for Gram-negative bacilli resistant to each of the rotation antibiotics. Pulsed-field gel electrophoresis analysis determined the numbers of genetically discordant resistant organisms on each team. The association between colonization with a resistant bacillus (the primary outcome) and team assignment was tested. RESULTS: A total of 1062 infants were studied during a 1-year period. A total of 10.7% infants on the rotation team versus 7.7% on the control team were colonized with a resistant bacillus. No interteam differences were distinguishable when the numbers of genetically discordant resistant organisms were normalized to the total number of team admissions. The incidence of nosocomial infection and mortality also were similar across teams. CONCLUSION: These data indicate that rotation of parenteral antibiotics according to the applied protocol has no detectable effect in decreasing the reservoir of resistant Gram-negative bacilli in a tertiary-care NICU.

Anti-Bacterial Agents↗
PubMed2006

Unilateral ibotenic acid lesions of the prefrontal cortex reduce rotational behavior in 6-hydroxydopamine-lesioned rats.

Rats with 6-hydroxydopamine (6-OHDA)-induced lesions of the substantia nigra are used as a model of Parkinson.s disease (PD), and these "lesioned" rats exhibit a rotational behavior when further injected with apomorphine (APO). We examined whether lesions in the prefrontal cortex (PFC) could modify the rotational behavior in PD model rats. Rats initially received unilateral lesions of the substantia nigra by 6-OHDA injection, and then their rotational behavior was measured. Two PFC lesions were achieved by intracerebral infusions of ibotenic acid, followed by measurement of APO-induced rotation. Rotation was reduced by approximately 30% after PFC injury. The PFC may have functional influence on the basal ganglia and may be involved in the pathophysiology of the rotational behavior of PD model rats.

Adrenergic Agents↗
PubMed1996

Adolescent idiopathic scoliosis. Correction of vertebral rotation with use of Wisconsin segmental spinal instrumentation.

We retrospectively reviewed the results of use of Wisconsin segmental spinal instrumentation in twenty-four patients who had adolescent idiopathic scoliosis. Our purpose was to determine whether there had been any correction of the rotational component. The mean age at the time of the operation was thirteen years and eight months (range, eleven to seventeen years). Computerized tomography was used to measure the degree of vertebral rotation relative to the midline of the body and relative to the mid-sagittal plane in thirty curves that had been treated with instrumentation and in fifteen that had not. According to the criteria of King et al., five patients had a type-I curve; fourteen, a type-II curve; four, a type-III curve; and one, a type-V curve. The mean correction in the coronal plane was 23 degrees (43 per cent; range, 20 to 69 per cent) for the curves that had been treated with instrumentation and 15 degrees (35 per cent; range, 11 to 77 per cent) for those that had not. The mean derotation of the apical vertebra, in relation to the midline of the body, in twenty-two curves that had been treated with instrumentation and that had had a mean initial rotation of 26 degrees (range, 8 to 53 degrees) was 6 degrees (range, 1 to 29 degrees). For seven curves, with a mean initial rotation of 25 degrees (range, 21 to 35 degrees), rotation increased a mean of 3 degrees (range, 1 to 7 degrees) after instrumentation. The rotation of the apical vertebra did not change in one curve treated with instrumentation. Derotation was seen in twelve of the fifteen curves that had not been treated with instrumentation.

Adolescent↗
PubMed1995

MR diagnosis of labral tears of the shoulder: value of T2*-weighted gradient-recalled echo images made in external rotation.

OBJECTIVE: Because several studies have shown that conventional MR imaging can fail to diagnose a significant percentage of labral tears, some authors have proposed obtaining T2*-weighted gradient-recalled echo images with the humerus in external rotation. The purpose of our study was to determine whether the diagnostic accuracy of detecting anteroinferior labral tears by MR imaging would be improved by adding a T2*-weighted gradient-recalled echo sequence with the humerus in external rotation. MATERIALS AND METHODS: The study included 24 patients for whom axial MR images of the shoulder were obtained with the humerus in both the neutral position and external rotation. Two observers interpreted the images made in the neutral position and then noted any change in their interpretations after viewing findings on the external-rotation images. MR results were correlated with surgical findings. At surgery, 14 anteroinferior labra were found to be torn and 10 were found to be intact. RESULTS: Both observers identified one patient for whom a surgically proved labral tear was seen only on the external-rotation images. The sensitivity increased from 0.43 to 0.50 (p = .35) for observer 1 and from 0.36 to 0.43 (p = .35) for observer 2. The specificity of 0.90 for both observers remained unchanged. The accuracy improved from 0.62 to 0.67 for observer 1 and from 0.55 to 0.62 for observer 2. CONCLUSION: The addition of external-rotation T2*-weighted gradient-recalled echo images to the MR examination for tears of the anteroinferior labrum leads to a small but statistically insignificant increase in diagnostic sensitivity. We conclude that the small increase in sensitivity does not justify the routine use of this sequence.

Adolescent↗
PubMed2002

Cardiac systolic rotation and contraction before and after valve replacement for aortic stenosis: a myocardial tagging study using MR imaging.

OBJECTIVE: Aortic stenosis leads to the derangement of cardiac function and contraction mode because of chronic pressure overload that is relieved after surgical valve replacement. The purpose of this study was to determine the changes in left ventricular systolic rotation and contraction using MR tagging in patients with aortic stenosis before and after surgical valve replacement compared with age-matched healthy volunteers. MATERIALS AND METHODS: Twelve patients with aortic stenosis were examined with an electrocardiographically triggered two-dimensional tagging sequence at 1.5 T before and 12 months after surgical valve replacement for the evaluation of wall function of the apical, mid ventricular, and basal levels. Eight healthy volunteers in the same age group served as the control group. RESULTS: Before surgery, all patients showed a significant increase of apical rotation (22.2 degrees +/- 5.9 degrees vs 10.3 degrees +/- 2.5 degrees, p < 0.0001) and overall left ventricular torsion (25.1 degrees +/- 6.6 degrees vs 14.5 degrees +/- 3.7 degrees, p < 0.001); basal rotation was not significantly different (-2.9 degrees +/- 2.1 degrees vs -4.2 degrees +/- 1.9 degrees, p = not significant) compared with the volunteer group. Apical rotation and torsion were negatively correlated with left ventricular mass (r = -0.73, p < 0.01, and r = -0.61, p < 0.05, respectively) and end-diastolic volume (r = -0.73, p < 0.01 and r = -0.64, p < 0.03, respectively). One year after surgery, basal rotation was reduced in the patients with aortic stenosis compared with the patients in the control group (-1.9 degrees +/- 1.8 degrees, p < 0.01). In comparison with preoperative values, apical rotation (14.2 degrees +/- 3.6 degrees, p < 0.01) also decreased but was still elevated, and this resulted in a normalization of left ventricular torsion (16.1 degrees +/- 3.7 degrees, p < 0.01). CONCLUSION: Surgical valve replacement for aortic stenosis leads to normalization of the left ventricular torsion 1 year after surgery. Pressure overload before surgery is associated with an increase of systolic left ventricular wringing motion, possibly serving as a compensatory mechanism. This mechanism declines with increasing left ventricular hypertrophy and dilatation.

Adult↗
PubMed2004

[Medial rotation deformity of the hip in cerebral palsy--surgical treatment by derotation femoral osteotomy].

Medial rotation deformity of the hip is a problem to patients handicapped by cerebral palsy who are able to walk, because the knees point inward during gait ("kissing patellae") and cause falls and frequent injuries, knee and ankle distorsions. The deformity is a result of an increased femoral neck anteversion. The purpose of the paper is to present the results of an original method of precise determination of the degree of rotation for derotation femoral osteotomy. Indications for this operation were set in patients with spastic form of cerebral palsy over 10 years of age, able to walk, who had difficulties in gait and whose lateral rotation was less than 15 along with the medial rotation of over 70 in the hip on the side of the deformity. Twenty hips in 17 patients able to walk were operated on. The average age was 21 (11 - 42), the average follow-up was 11 years (3-17). The assessment of the results was based on the comparison of the rotational abilities of the hip and individual problems before and after the operation. Excellent result was achieved in 12 (70.6%) patients i.e. 15 (75%) hips; good result was achieved in 3 (17.6%) patients i.e. 3 (15%) hips; unsuccessful result in 2 (11.8%) patients i.e. 2 (10%) hips. Complications aroused in 6 patients i.e. 6 (30%) hips. The conclusion is that derotation osteotomy of the femur is a successful procedure for the treatment of the medial rotation deformity of the hip in patients with the spastic form of cerebral palsy who are able to walk. The above mentioned indications must be respected and the original method of determining the degree of derotation applied. Due to a relatively high percentage of complications, e.g. osteitis, the operation is suggested to patients aged 10 to 15 when possible complications can more easily be cured.

Adolescent↗
PubMed1997

Adaptation to optokinetic rotation-induced motion sickness without experiencing nausea.

17 subjects highly susceptible to motion sickness were divided into Nausea and No-nausea groups depending upon whether the subjects experienced nausea during adaptation to nauseagenic rotation. Eight subjects in the Nausea group viewed an optokinetic rotation drum for repeated sessions of 16 min., with an interval of two days between every two sessions. During each session the subjects continuously viewed the rotating drum 16 min. even if they experienced nausea. nine subjects in the No-nausea group likewise viewed an optokinetic rotation drum for at most 16 min. but immediately stopped viewing the rotating drum whenever they experienced nausea during the session. The criteria for full adaptation were that the subject reported no feelings of stomach discomfort and nausea during a 16-min session. The mean number of sessions to reach full adaptation was 3.9 (SD = 0.6) with a range 3 to 5 sessions for the subjects in the Nausea group and 3.2 (SD = 0.8) with a range 2 to 4 for the subjects in the No-nausea group. It was concluded that subjects can adapt to a nauseagenic optokinetic rotation by repeated exposure without experiencing nausea and vomiting during adaptation.

Adaptation, Physiological↗
PubMed2001

Mental rotation and real-world wayfinding.

Sex differences in mental rotation skills are a robust finding in small-scale laboratory-based studies of spatial cognition. There is almost no evidence in the literature, however, relating these skills to performance on spatial tasks in large-scale, real-world activities such as navigating in a new city or in the woods. This study investigates the connections between mental rotation skills as measured by the Vandenburg-Kuse Mental Rotations test and the performance of college students (n=211) navigating a 6-km orienteering course. The results indicate that mental rotation skills are significantly correlated with wayfinding performance on an orienteering task. The findings also replicate sex differences in spatial ability as found in laboratory-scale studies. However, the findings complicate the discussion of mental rotation skills and sex because women often performed as well as men despite having lower mean test scores. This suggests that mental rotation ability may not be as necessary for some women's wayfinding as it is for men's navigation.

Female↗
PubMed2003

Improved mental rotation by near-sighted subjects.

Several studies have shown significant correlations among factors such as sex, age, and hormone levels with performance on mental rotation tasks. To perform spatial rotation also seems to be related to cognitive abilities such as musical skills. The present experiment investigated a possible relationship for enhanced spatial abilities, as observed in near-sighted subjects, with mental rotation performance. 39 near-sighted and 21 normal-sighted subjects were tested on a mental rotation task using two-dimensional representations of three-dimensional objects. Near-sighted subjects displayed fewer errors in possible rotations than normal-sighted subjects. There was no difference in errors between groups in identification of mirror images ("impossible rotations"). Results were interpreted in terms of a relation between enhanced reliance on nonvisual information by near-sighted subjects and improved spatial representation.

Adult↗
PubMed1996

The effects of isokinetic vs. plyometric training on the shoulder internal rotators.

Plyometric training has become a popular training and rehabilitation tool. The purpose of this study was to compare the effects of plyometric and isokinetic concentric/eccentric training of the shoulder internal rotators. Female subjects (N = 78) were randomly assigned to three groups: control, isokinetic training, and plyometric training. Pre-/posttesting measurements included: 1) concentric/eccentric isokinetic power measurements of the shoulder internal rotators at 60 degrees/sec, 180 degrees/sec, and 240 degrees/sec; 2) kinesthetic measurements of shoulder internal rotation, external rotation < 45 degrees, and external rotation > 45 degrees; and 3) a softball distance test. Both groups trained twice a week for 8 weeks. Power and kinesthetic data were analyzed using multiple analyses of variance with repeated measures. A one-way analysis of variance was performed on the softball throw data. No significant (p < .05) pre-/posttest differences were found with kinesthetic testing or the softball throw. Pre-/postpower differences were significantly greater for the isokinetic group at 60 degrees/sec eccentric, 120 degrees/sec concentric and eccentric, and 240 degrees/sec concentric and eccentric. Isokinetic training of the shoulder internal rotators increases isokinetic power, but neither isokinetic nor plyometric training resulted in a functional improvement with the softball throw.

Adolescent↗
PubMed2003

The influence of tibial and femoral rotation on patellofemoral contact area and pressure.

Fixed rotation of either the femur or tibia has a significant influence on the patellofemoral joint contact areas and pressures. This is due to the anatomic asymmetry in the knee with respect to all planes, as well as the laterally directed force vector that naturally exists in bipedal lower-limb biomechanics. Specifically, femoral rotation results in an increase in patellofemoral contact pressures on the contralateral facets of the patella, and tibial rotation results in an increase in patellofemoral contact pressures on the ipsilateral facets of the patella. This difference can be elucidated when one considers that rotation of the femur is biomechanically different than rotation of the tibia. For both tibial and femoral rotations, the patella's distal attachment to the tibial tubercle influences the direction of patellar movement. The biomechanical evidence reviewed in this manuscript suggests that the determining factor in patellofemoral pathology is the derangement of normal joint mechanics. However, despite considerable experimental data supporting this position, there also are theories that suggest otherwise. This illustrates a very important point in patellofemoral joint pathology, where no one factor may be the sole defining etiology. Instead, the patellofemoral joint is one of the most complex diarthrodial joints in the body and there are a number of etiologic factors that can lead to pathology. This should be considered for developing repair and rehabilitation strategies.

Arthralgia↗
PubMed2005

Effect of rotation frequency and weaning date on forage measurements and growth performance by cows and calves grazing endophyte-infected tall fescue pastures overseeded with crabgrass and legumes.

A grazing study was initiated in April 2000 and continued through three calving and weaning cycles (ending July 2003) to investigate the effects of rotational grazing management (twice monthly [2M] vs. twice weekly [2W]) and weaning date (mid-April [EARLY] vs. early June [LATE]) on production of fall-calving cow-calf pairs (495 +/- 9.6 kg initial BW) grazing Neotyphodium coenophialum-infected tall fescue (Festuca arundinacea Schreb.) overseeded with legumes and crabgrass. Secondary objectives of the experiment were to monitor differences in quantity and quality of available forage and to evaluate changes in forage species composition. Pastures were dominated by tall fescue throughout the study, and the proportion of basal cover was greater (P < 0.05) in 2M than in 2W pastures. The percentage of legumes was very low across all treatment combinations, but the percentage of crabgrass continued to increase (P < 0.05) linearly and quadratically across years for both summer and fall sampling periods, regardless of rotation or weaning program. In vitro DM disappearance and mineral concentrations varied minimally because of rotation frequency or weaning date. Rotation frequency did not substantially affect (P = 0.11 to 0.97) cow BW, hay offered, milk production, calving interval, calf birth weight, or actual or adjusted weaning weights; however, 2M cows had 0.3 units higher (P < 0.05) BCS at the time of breeding than 2W cows. Calves weaned late had greater (P < 0.05) actual weaning weight and weighed more (P < 0.05) on the LATE weaning date than on the EARLY weaning date, but 205-d adjusted weaning weights did not differ (P = 0.74) across weaning dates. Therefore, rotation frequency and/or weaning date had little effect on forage species composition or forage quality. In addition, the rapid rotation program offered little advantage with respect to animal performance, and weaning fall-born calves grazing endophyte-infected tall fescue pastures at approximately 189 d of age seemed to be detrimental to calf performance compared with delaying weaning until 243 d of age.

Acremonium↗
PubMed2005

Deep digital flexor tendon force and digital mechanics in normal ponies and ponies with rotation of the distal phalanx as a sequel to laminitis.

REASONS FOR PERFORMING STUDY: Previous studies have implicated tension in the deep digital flexor tendon (DDFT) in the rotation of the distal phalanx (DP) after the breakdown of the dorsal laminae caused by laminitis. Howeveer, once the DP has rotated, the DDFT should become shorter, reducing the force it exerts on the DP. OBJECTIVE: To compare DDFT force and ground reaction forces (GRFs) in normal ponies and ponies with rotation of the DP as a sequel to laminitis. METHODS: Six normal ponies (Group 1) and 6 sound ponies with 6-13 degrees of rotation of the DP in relation to the dorsal hoof wall (Group 2) were assessed at trot using forceplate and motion analysis. The force in the DDFT was calculated by assuming that the extending moment at the distal interphalangeal (DIP) joint resulting from the GRF was equal to the flexing moment created by the force in the DDFT during the stance phase (inverse dynamics). RESULTS: In early stance, the peak DDFT force (mean+/-s.d.) in the normal ponies was 1.92+/-1.63 N/kg. However, in Group 2, the point of zero moment was palmar to the centre of rotation of the DIP joint for the first 40% of stance and hence DDFT force was zero. Force in the DDFT reached a peak of 10.00+/-3.56 N/kg at 60.7+/-5.6% of stance in Group 1 and 6.41+/-1.37 N/kg at 79.2+/-9.6% of stance in Group 2. CONCLUSIONS: DDFT force in Group 2 laminitic ponies was much reduced until late stance, when it neared normal values. POTENTIAL RELEVANCE: Further studies of ponies with rotation of the DP as a sequel to laminitis should assist farriery aimed at reducing the force in the DDFT through the breakover phase of stance to protect damaged dorsal laminae.

Animals↗
PubMedDate not supplied

Rotated stereociliary bundles and their relationship with the tectorial membrane in the guinea pig cochlea.

Hair cells with rotated stereociliary bundles have been observed in the cochleae of control and kanamycin-treated guinea pigs. The affected outer hair cell bundles have a variable degree of rotation, with some being completely reversed. The inner hair cells are more rarely affected, and only small areas of an individual inner hair cell bundle are abnormal. In counts from ten cochleae, the number of outer hair cells with rotated bundles was most commonly between 10% and 20%, with almost 27% of all outer hair cells affected in the most extreme case. The rotated outer hair cell bundles often have distorted outlines but in other respects closely resemble normal bundles. In particular, they have the usual gradation in stereociliary height, intracellular cross-links and intercellular links to adjacent normally-orientated bundles. There are also corresponding imprints in the tectorial membrane which match the pattern of the stereocilia. In kanamycin-treated guinea pigs, imprints of both normal and rotated hair bundles are present, even when the corresponding bundle is absent, and there are frequently remnants of stereocilia inserted in the imprints. These observations suggest that, apart from their abnormal orientation, the rotated bundles are similar to normal bundles in both their organization and association with the tectorial membrane. The implications of this with respect to transduction and cochlear mechanics are discussed.

Animals↗
PubMed1984

Instability of total hip prostheses at rotational stress. A roentgen stereophotogrammetric study.

Roentgen stereophotogrammetric analysis (RSA) has been carried out on 24 total hip prostheses (24 patients), which were all painful at weightbearing. The examinations were made with the hip at distraction, compression, external and internal rotation. One acetabular component showed instability only at distraction-compression and one showed instability only at rotation. Four femoral components showed instability at distraction-compression and at rotation, six only at rotation, but none showed instability only at distraction-compression. Thus rotational provocation demonstrated instability in all unstable femoral components; rotational stress must be of importance in mechanical loosening of the femoral component.

Acetabulum↗
PubMed1992

The influence of intensively managed rotational grazing, traditional continuous grazing, and confinement housing on bulk tank milk quality and udder health.

Monthly bulk tank milk samples and veterinary records were analyzed for 1 yr on 15 Vermont dairy farms. Data were evaluated using ANOVA to compare effects of grazing management systems on milk quality and udder health. Systems evaluated were intensively managed rotational grazing, traditional continuous grazing, and confinement housing. Bulk tank samples were evaluated for standard plate count, bacterial type counts on tryptose-blood-esculin agar, and SCC. Veterinary records were evaluated for incidence of clinical mastitis, udder edema, and teat injuries. Within- and between-treatment group analyses were conducted by season, herd size, and udder sanitation systems. Mean standard plate counts were lower in rotationally grazed herds than counts of confined herds during the grazing season. Similarly, rotationally grazed herds with fewer than 60 cows had lower standard plate counts than confined herds of similar size. Mean bulk tank counts of streptococci other than Streptococcus agalactiae during the grazing season differed among treatments. The lowest counts occurred in rotationally grazed herds. Among herd using predip products recognized as efficacious, fewer streptococci other than S. agalactiae were isolated from bulk tank milk of rotationally grazed herds than confined herds. Rotationally grazed herds using postdips recognized as efficacious had lower SCC than those using unrecognized postdips. No udder health differences were observed among grazing treatments.

Animal Husbandry↗
PubMed1995

Can mental rotation begin before perception finishes?

We conducted six experiments to determine if mental rotation can begin before perception finishes, as allowed by continuous flow models but not discrete state models of information processing. The results of Experiments 1-3 showed that the effect of shape discriminability on RT was underadditive with the effect of stimulus orientation, suggesting that mental rotation began before shape discrimination had finished and that the two processes overlapped in time. The results of experiments 4-6 indicated that mental rotation can overlap with color discriminations as well. In both sets of experiments, however, the amount of underadditivity tended to be much less than predicted by models allowing interference-free overlap. This suggests that mental rotation can overlap with perceptual analysis, contrary to fully discrete models, but that little rotation is carried out during this overlap due to interference between simultaneous discrimination and rotation processes.

Adult↗