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At least 19 recordsLinked to original sources
PubMed1996

The J-coupling restrained molecular mechanics (JrMM) protocol--an efficient alternative for deriving DNA endocyclic torsion angle constraints. Part I: Correlation of endocyclic torsion angles and vicinal torsion angle phi 1'2'.

An efficient alternative which makes use of the reliable 3J1'2' value to derive the endocyclic torsion angle constraints is proposed in this study. Based on the information embedded in the two plots, (i) the vicinal proton-proton J-couplings, 3J1'2', 3J1'2", 3J2'3', 3J2"3' and 3J3'4' against the pseudorotation phase angle, and (ii) 3J1'2", 3J2'3', 3J2"3' and 3J3'4' against 3J1'2'; using the calculated J-couplings obtained for a range of sugar geometries of deoxyribose ring in nucleosides and nucleotides encountered along the pseudorotation itinerary [J. van Wijk, B.D. Huckriede, J.H. Ippel and C. Altona, Methods Enzymol. 211, 286-306 (1992)], it is suggested that the vicinal 3J1'2' possesses structural information other than the vicinal torsion angle phi 1'2'. This study is divided into two parts. In Part I, a correlation diagram between the endocyclic torsion angles nu(i) (i = 0,1,2,3,4) and the restrained vicinal torsion angle phi 1'2' is obtained through the use of the J-coupling restrained molecular mechanics (JrMM) protocol. The established phi 1'2'-nu(i) correlation shows nu(i) can be deduced from the reliable 3J1'2' value and it forms the basis for developing an alternative protocol to derive endocyclic torsion angle constraints. In Part II of this series, extensive testing demonstrating the validity of the JrMM protocol to derive nu(i) for defining the sugar geometry of solution DNA molecules is presented.

Computer Simulation↗
PubMed1998

A retrospective review of pediatric patients with epididymitis, testicular torsion, and torsion of testicular appendages.

STUDY OBJECTIVE: To compare historical features, physical examination findings, and testicular color Doppler ultrasound in pediatric patients with epididymitis, testicular torsion, and torsion of appendix testis. METHODS: A retrospective review of patients with the diagnosis of epididymitis, testicular torsion, or torsion of appendix testis. RESULTS: Ninety patients were included in the study (64 with epididymitis, 13 with testicular torsion, and 13 with torsion of appendix testis). Historical features did not differ among groups except for duration of symptoms. Of 13 patients with testicular torsion all had a tender testicle and an absent cremasteric reflex. When compared with the testicular torsion group, fewer patients with epididymitis had a tender testicle (69%) or an absent cremasteric reflex (14%). 62 (97%) patients with epididymitis had a tender epididymis and 43 (67%) had scrotal erythema/edema. By comparison, 3 (23%) and 5 (38%) patients with testicular torsion had a tender epididymis or scrotal erythema/edema, respectively. Doppler ultrasound showed decreased or absent blood flow in 8 patients, 7 of whom were diagnosed with testicular torsion. Ten out of 13 patients with testicular torsion had a salvageable testicle at the time of surgery. CONCLUSION: The physical examination is helpful in distinguishing among epididymitis, testicular torsion, and torsion of appendix testis. Patients presenting with a tender testicle and an absent cremasteric reflex were more likely to have a testicular torsion rather than epididymitis or torsion of appendix testis. An absent cremasteric reflex was the most sensitive physical finding for diagnosing testicular torsion. Color Doppler ultrasound is a useful adjunct in the evaluation of the acute scrotum when physical findings are equivocal.

Adolescent↗
PubMed1998

Signs of surface torsion and torsional dioptric power.

Although there is agreement in the literature over the magnitude of torsion and torsional dioptric power, there is ambiguity over the signs of those quantities. The purpose of this paper is to define terms in such a way that the ambiguity is removed. Explicit equations are presented for torsion and torsional power along a meridian of a surface. In keeping with common practice in other disciplines, right-handed torsion is chosen to be positive. The components of the dioptric power matrix of thin systems and of the reduced vergence matrix are reinterpreted in terms of curvital and torsional power. In this reinterpretation the off-diagonal components of the matrices remain the torsional power and the reduced torsion along the meridian orthogonal to the reference meridian. However, they become the negatives of those quantities along the reference meridian. In particular, the top-right component can be interpreted as the reduced torsion or the torsional power along the meridian orthogonal to the reference meridian and the bottom-left as the negative of those quantities along the reference meridian. Torsion and torsional power along a meridian, as well as curvature and curvital power, are invariant under change of reference meridian and under spherocylindrical transposition.

Eyeglasses↗
PubMed2002

Adnexal torsion in children may have a catastrophic sequel: asynchronous bilateral torsion.

BACKGROUND/PURPOSE: Adnexal torsion is a serious condition that frequently may result in ovarian removal, and there always is a risk of castration if the contralateral ovary undergo torsion as well. In this study, the authors present their experience with adnexal torsion in 15 children and describe a catastrophic event, asynchronous bilateral adnexal torsion, with review of the literature. METHODS: Between November 1993 and November 2000, 15 children under 15 years of age who had undergone operation because of torsion of uterine adnexal structures were evaluated. Two illustrative cases with asynchronous bilateral adnexal torsion are presented. RESULTS: Fourteen cases were associated with additional adnexal pathology, whereas in 1 case the torsion was of normal uterine adnexa. Sonographic studies improved the preoperative diagnosis. Hemorrhagic necrosis of the adnexa secondary to the torsion was found in all cases except 3 and necessitated adnexal resection. In only 3 cases preservation of the adnexa was possible. Asynchronous adnexal torsion occurred in 2 patients in the time course. Both were treated by laparotomy and adnexal untwisting and fixation by permanent multiple interrupted sutures. In their final evaluation at 40 and 8 months after the operation, they were found to have good ovarian function. CONCLUSION: Considering the risk of subsequent contralateral torsion and its impact on future fertility, the authors believe that conservative management (untwisting the ovary and pexing, both retained detorsed and contralateral, ovaries) should be considered in cases of ovarian torsion in children.

Abdominal Pain↗
PubMed1984

[A study on torsion of the lower leg in osteoarthritis of the knee. Measurement of leg torsion by computerized tomography].

UNLABELLED: Lower leg torsion was measured by computerized tomography (CT-scan) in the knees with osteoarthritis. MATERIALS AND METHODS: Experimental studies; Using the Toshiba CT/TCT-60A, the degree of torsion in five dried tibias were measured in three positions of varus, 0 degrees, 10 degrees and 20 degrees; and in two positions of flexion 0 degrees and 20 degrees. Clinical studies; The degree of tibial torsion was measured by CT-scan in 68 adult patients (85 knees) and compared with the torsion in 13 controls (24 tibias). The correlation between tibial torsion and osteoporosity was investigated by measuring CT-density of the third lumbar vertebra. RESULTS: No statistically significant difference was found among the results of measurement obtained in five dried tibias placed in three positions of varus and in two positions of flexion. These results indicate that measurement of torsion using CT-scan is not influenced by the position when varus and flexion deformity are less than 20 degrees. Osteoarthritic knees were divided into five radiographic stages. There were significant differences between the lateral tibial torsions for each stage. The lateral tibial torsion was 23.5 degrees in normal adults, 14.1 degrees in stage II, 11.9 degrees in stage III, 7.5 degrees in stage IV and V, for an average of 11.3 degrees. The rate of decrease in lateral tibial torsion was 59.6% in the proximal tibia, 4.2% in the tibial shaft and 36.2% in the distal tibia. The decreases of lateral tibial torsion were correlated with decrease of CT-density of the third lumbar vertebra. CONCLUSION: It is apparent from this study that there is a correlation between decreasing lateral tibial torsion with the radiographic stage of osteoarthritis of the knee and general osteoporosity.

Adult↗
PubMed2000

Torsional Splitting in the Degenerate Vibrational States of (70)Ge(2)H(6): Rotation-Torsion Analysis of the nu(7) and nu(9) Fundamentals.

The rotational and torsional structure of the nu(7) and nu(9) degenerate fundamentals of (70)Ge(2)H(6) has been analyzed under high resolution. The torsional structure of both v(7) = 1 and v(9) = 1 states can be fitted by a simple one-parameter formula. The x,y-Coriolis interaction with the parallel nu(5) fundamental was accounted for in the analysis of nu(7). A strong perturbation of the J structure of the E(3s) torsional component of the KDeltaK = -2 subbranches of nu(9) can be explained by the resonance with an E(3s) excited level of the pure torsional manifold. The perturber is centered at 361.58 cm(-1), very close to the value estimated with a barrier height of 285 cm(-1). This confirms that the fundamental torsional wavenumber is close to 103 cm(-1), in good agreement with the "ab initio" prediction. The torsional splittings of all the infrared active degenerate fundamentals, nu(7), nu(8), and nu(9), follow the trend predicted by theory, and have been fitted by exploratory calculations accounting only for the torsional Coriolis-coupling mechanism of all degenerate vibrational fundamentals in several torsional states. This confirms that torsional Coriolis coupling is the dominant mechanism responsible for the decrease of the torsional splitting in the degenerate vibrational states. A higher value of the barrier had to be used for the nu(9) mode. Copyright 2000 Academic Press.

Journal Article↗
PubMed2005

Paradoxical increase in ventricular torsion and systolic torsion rate in type I diabetic patients under tight glycemic control.

OBJECTIVES: This study sought to characterize the early features of diabetic cardiomyopathy by magnetic resonance imaging (MRI) tagging. BACKGROUND: The earliest manifestations of diabetic cardiomyopathy have not been well established, especially under tight glycemic management. We hypothesized that torsion measurements would identify subclinical contractile alterations in type I diabetics with normal left ventricular ejection fraction, mass, blood pressure, and aggressive glycemic control. We also sought to characterize the influence of elevated resting heart rates (HRs) of diabetics on torsion. METHODS: Sixteen patients with type I diabetes and 10 control patients underwent cine and tagged MRI with a 1.5-T scanner. Torsion, strain, and their rates were measured. To quantify the influence of chronotropic and inotropic stimulation on torsion, nine healthy volunteers underwent MRI tagging at rest, after atropine injection, and after exercise. RESULTS: Diabetic patients (hemoglobin A1c, 6.8 +/- 0.4%) had a higher resting HR (77.0 +/- 12.4 beats/min vs. 59.0 +/- 5.6 beats/min; p < 0.01), higher maximal torsion by 23% (3.5 +/- 0.9 degrees/cm vs. 2.7 +/- 0.4 degrees/cm; p < 0.01) and higher maximal systolic torsion rate (TR-s) by 25% (0.013 +/- 0.003 degrees/cm/s vs. 0.010 +/- 0.002 degrees/cm/s, p = 0.01). Torsion did not significantly change with chronotropic stimulation (p = 0.30). CONCLUSIONS: In diabetics under tight glycemic control, we observed a surprising increase in torsion and TR-s unrelated to chronotropic influences of HR. We propose that increased torsion and TR-s could represent early predictive markers of the propensity to cardiac dysfunction in asymptomatic type I diabetics. Furthermore, these findings seem fundamental to the diabetic state itself and unaccounted for by other comorbidities.

Adult↗
PubMedDate not supplied

[Torsion movements of the human eye. IV. Passive body movements, effect of skeletal muscle reflexes, opticokinetic torsion tracking].

A comparative study of torsional movement of the eye in passive and active tilting of the head and body of the object was carried out. Similarity of torsional movement of the eyes in passive and active movements was shown. It was found by the method of exclusion and selective stimulation of vestibular, cervikal, lumbar optokinetic reflexes, that neither the cervikal, nor lumbar reflexes elicited spontaneous torsional movements of the eyes and had no influence on them. A direct study (coinciding with rotation direction of the stimulus of head rotation) and the reverse (noncoinciding) torsional tracing of a rotating disc and tracing without head movements was investigated. During direct tracing depression of saccades and extention of the slow phase of torsion was found; during the reverse one--a decrease of the eye drist and increase of the amplitude and number of saccades. Phenomena of a seeming acceleration and deceleration of disc rotation etc. have been observed. It was found that with torsional saccades vision was retained. The presence of optokinetic control of phases of torsional eye movements formation has been recorded. Tracing without rotation of the head was accompanied by torsional nistagmus. Possible causes of incomplete stabilisation and optokinetic torsional tracing are discussed.

Eye Movements↗
PubMed2006

Testicular fixation following torsion of the spermatic cord--does it guarantee prevention of recurrent torsion events?

PURPOSE: Patients with history of testicular torsion who have undergone orchiopexy may rarely present with acute scrotum due to recurrent episodes of torsion. Most of the reports in the literature regarding this scenario refer to the era when absorbable sutures were used for testicular fixation. Herein, we review our experience in recent years, focusing upon the surgical technique and sutures' material. MATERIALS AND METHODS: Between 1991 and 2003, 179 patients were operated on at our institute with the clinical diagnosis of unilateral testicular torsion. They ranged in age between neonates to 45 years old (average age 18). In a comprehensive retrospective study we managed to locate 8 patients who experienced recurrent intravaginal testicular torsion following previous fixation performed in our institute. RESULTS: The patients who experienced repeat torsion have initially presented at the mean age of 18.5 years old (range 12 to 30) with unilateral twisted testicle (left 3, right 5). Urgent explorations were generally performed, apart from in 2 cases that underwent spontaneous detorsion which was followed by an elective surgery. Testicular fixation was conducted by suturing of the tunica albuginea to the dartos layer by 2 sutures at each side, using chromic 3-zero in the 3 more early cases, followed by the usage of polyglactin 3-zero stitches in 4 subsequent cases and 3 sutures of polypropylene 4-zero for each testicle, thereafter, in the most recent case. The patients presented with repeat torsion, 0.5 to 23 years subsequently (average 7 years), involving either the ipsilateral testicle in 4 cases or the contralateral gonad in 4. CONCLUSIONS: Recurrent torsion following previous testicular fixation may appear many years following the primary procedure, even in cases in which either polyglactin or, notwithstanding, polypropylene sutures have been applied, in accordance with the common practice used in the last 2 decades. Increased awareness regarding this possibility is imperative for early diagnosis and prevention of testicular loss.

Adolescent↗
PubMed1995

[NMR tomographic measurement of femoral ante-torsion and tibial torsion].

PURPOSE: A new MRI method for the measurement of femoral torsion and tibial torsion is presented. METHODS: Axial images were generated using a standard gradient echo sequence (FLASH 2D). Otherwise measurement of femoral and tibial torsion was performed according to an established CT method. RESULTS: The torsion angles measured using MRI were in accordance with the angles measured using the CT method. The MRI method was not more time-consuming than the CT method. CONCLUSION: In respect of radiation exposure, MRI determination of femoral and tibial torsion should be considered particularly in children and patients who have to undergo repeated torsion measurements.

Adolescent↗
PubMed1992

[Femoral and tibial bone torsions associated with internal femoro-tibial osteoarthritis. Index of cumulative torsions].

Among the hypothesis about pathogenesis of medial knee osteoarthritis, the participation of modifications of the alignment of the limb in the frontal plane is known. The participation of the femoral and tibial torsions had been assessed by a few authors. In this study, the torsions have been measured by computerized tomodensitometry. The global torsional morphology of the limb has been defined by the measure of the Index of Cumulated Torsions. The values of torsions have been compared with the angle deformities measured in the frontal plane. The effects of the bone torsions on the position of the lower limb during the weight-bearing phase of the gait and the consequences about the knee have been studied.

Aged↗
PubMed2006

Torsion of the appendix mimicking ovarian torsion.

BACKGROUND: Appendiceal torsion is rare and generally seen more frequently in children than adults. Untreated it can lead to necrosis, ulceration, and subsequent peritonitis. CASE: A middle-aged female presented with a 5-day history of cramping abdominal pain and nausea and vomiting. Abdominal wall guarding and rebound tenderness was noted on examination. Computerized tomography showed an 8 x 4 cm mass anterior to the uterus, suggestive of degenerating fibroid versus ovarian dermoid cyst. Laparoscopy was performed for presumed ovarian torsion. Torsion of the appendix was discovered and treated by laparoscopic appendectomy. CONCLUSION: Patients with presumed ovarian torsion should undergo urgent laparoscopy for diagnosis and attempted ovarian salvage. The possibility of conditions that may require different surgical interventions, such as appendiceal torsion, should be considered.

Appendix↗
PubMed2004

Changes in ocular torsion position produced by a single visual line rotating around the line of sight--visual "entrainment" of ocular torsion.

A large- or full-field visual stimulus slowly rotating around the naso-occipital axis of an observer causes both eyes to tort, and many of the factors controlling this optokinetic torsional response have been identified. The present study reports that a single line rotating about the line of sight can cause both eyes to tort in the same direction as the stimulus but with a low gain. We have used the term 'entrainment' to describe this torsional response. This paper reports some of the factors associated with entrainment. Video measures of 3-d eye position were recorded while the subject made settings of a simple visual line to subjective visual horizontal (SVH) and vertical (SVV) using the standard method-of-adjustment paradigm. The visual line was composed of 11 light-emitting diodes; the line subtended a visual angle of 19 degrees, and moved at a constant speed of 4.8 degrees /s. Settings were made in an otherwise darkened room, and also in the light. Subjects were required to maintain fixation of the central LED while making settings from starting positions 10 or 20 degrees either side of gravitational horizontal or vertical. We show that entrainment of ocular torsion by the single moving visual line is low in gain but a reliable and repeatable effect and that (1) there are considerable individual differences between subjects but within-subject consistency, (2) all subjects show larger and more consistent torsional entrainment for lines moving to SVH than lines moving to SVV, (3) the strongest entrainment generally occurs within about 10 degrees of the target position, and (4) entrainment is also present in the light, though with slightly reduced gain.

Adaptation, Ocular↗
PubMed1994

Postoperative pulmonary torsion: report of a case and survey of the literature including spontaneous and posttraumatic torsion.

A case of postoperative torsion of the left upper lobe following thoracotomy for removal of a large mediastinal tumor is presented. Diagnosis was made on the sixth postoperative day by axial computerized tomography. At rethoracotomy the upper lobe, well delimited against the lower lobe by deep fissure, was found to be twisted by 180 degrees in clock-wise direction. It was hemorrhagically infarcted and had to be resected. The patient, a 37-year-old woman, made an uneventful recovery thereafter. In a recent epidemiological study in the United Kingdom it could be shown that postoperative torsion occurs more frequently than hitherto presumed. 35 of 117 thoracic surgeons responding to a questionnaire had observed this complication 36 times. In reviewing the literature for welldocumented cases, four cases of spontaneous, five of posttraumatic, and 17 cases of postoperative pulmonary torsion were found. Of these cases and the case reported 12 torsions occurred after partial lung resection and six following other thoracic operations. Especially the right middle lobe is endangered after upper lobectomy and should be fixed to the lower lobe during surgery. The outcome was fatal in 4 of the 18 cases. Prevention and treatment are discussed.

Adult↗
PubMed1976

[Torsional movements of the human eye. II. Slow phase of torsion].

At different experimental conditions quantitative characteristics of the slow phase of the torsional eye movements were investigated. We found the torsional drift to increase when the head tilted faster and its velocity was bigger in the dark than in the light. Asymmetry of the drift velocity was found on moving the head to and backward. It was shown that the sign of the asymmetry did not depend on rotatory movements of the cup (the suction device for eye movement registration). At the same time electric stimulation of the labyrinth changed the sign of asymmetry and without head tilting led to the torsional eye movements (nistagmus). Some subjects were able to decline the number of the torsional saccades at will, and as a result the eye made a drift up to tens of degrees long. Possible causes of imperfect vestibular and optokinetic compensation in the eye trosion were discussed.

Ear, Inner↗
PubMed1996

Torsional rigidity of single actin filaments and actin-actin bond breaking force under torsion measured directly by in vitro micromanipulation.

Knowledge of the elastic properties of actin filaments is crucial for considering its role in muscle contraction, cellular motile events, and formation of cell shape. The stiffness of actin filaments in the directions of stretching and bending has been determined. In this study, we have directly determined the torsional rigidity and breaking force of single actin filaments by measuring the rotational Brownian motion and tensile strength using optical tweezers and microneedles, respectively. Rotational angular fluctuations of filaments supplied the torsional rigidity as (8.0 +/- 1.2) x 10(-26) Nm2. This value is similar to that deduced from the longitudinal rigidity, assuming the actin filament to be a homogeneous rod. The breaking force of the actin-actin bond was measured while twisting a filament through various angles using microneedles. The breaking force decreased greatly under twist, e.g., from 600-320 pN when filaments were turned through 90 degrees, independent of the rotational direction. Our results indicate that an actin filament exhibits comparable flexibility in the rotational and longitudinal directions, but breaks more easily under torsional load.

Actins↗
PubMedDate not supplied

[Torsion movements of the human eye. III. Rapid phase of torsion].

Kinematic characteristics of torsional saccades and their peculiarities were investigated. The torsional saccades were found to occur simultaniously in both eyes and had the same size and duration. It was shown that the peak velocity and the duration of the saccades depend on their amplitudes. The number of the saccades decreased and their sizes increased when the head tilts were faster. In the case intervals between the saccades decreased up to 20-30 ms. The likeness of the torsional movements and rotatory nistagmus was discussed.

Biophysical Phenomena↗