Torsional Mechanism Research Articles

A role for anions in ATP synthesis and its molecular mechanistic interpretation

ATP, the 'universal biological energy currency', is synthesized by utilizing energy either from oxidation of fuels or from light, via the process of oxidative and photo-phosphorylation respectively. The process is mediated by the enzyme F(1)F(0)-ATP synthase, using the free energy of ion gradients in the final energy catalyzing step, i.e., the synthesis of ATP from ADP and inorganic phosphate (P(i)). The details of the molecular mechanism of ATP synthesis are among the most important fundamental issues in biology and hence need to be properly understood. In this work, a role for anions in making ATP has been found. New experimental data has been reported on the inhibition of ATP synthesis at nanomolar concentrations by the potent, specific anion channel blockers 4,4'-diisothiocyanostilbene-2, 2'-disulphonic acid (DIDS) and tributyltin chloride (TBTCl). Based on these inhibition studies, attention has been drawn to anion translocation (in addition to proton translocation) as a requirement for ATP synthesis. The type of inhibition has been quantified and an overall kinetic scheme for mixed inhibition that explains the data has been evolved. The experimental data and the type of inhibition found have been interpreted in the light of the torsional mechanism of energy transduction and ATP synthesis (Nath J Bioenerg Biomembr 42:293-300, 2010a; J Bioenerg Biomembr 42:301-309, 2010b). This detailed and unified mechanism resolves long-standing problems and inconsistencies in the first theories (Slater Nature 172:975-978, 1953; Williams J Theor Biol 1:1-17, 1961; Mitchell Nature 191:144-148, 1961; Mitchell Biol Rev 41:445-502, 1966), makes several novel predictions that are experimentally verifiable (Nath Biophys J 90:8-21, 2006a; Process Biochem 41:2218-2235, 2006b), and provides us with a new and fruitful paradigm in bioenergetics. The interpretation presented here provides intelligent answers to the unexplained existing results in the literature. It is shown that mechanistic interpretation of the experimental data requires substantial addition to available conceptual foundations such that present concepts, theories, and mechanisms must be revised.

Ectopic Ovary at Ectopic Pregnancy

Fig. 1. Twisted left tubal ectopic pregnancy with ectopic left ovary (OV). A 33-year-old woman presented at the emergency department with a 3-day history of abdominal pain and mild vaginal bleeding at 7 weeks amenorrhea. She was anxious but with stable vital signs (blood pressure 115/78 mmHg, pulse rate 86). The serum b-human chorionic gonadotropin level was 1226 IU/mL, and transvaginal ultrasonography, done with moderate discomfort, revealed hemoperitoneum, an empty uterus, and an adnexal mass adjacent to the left ovary suggestive of a tubal ectopic pregnancy. Emergency laparoscopy revealed a twisted left tubal ectopic pregnancy wrapping around a left ectopic ovary attached near the uterosacral ligament. The ovary had no ovarian or infundibulopelvic ligament but only rudimentary vascular attachment to the base of the broad ligament lateral to the uterosacral ligament (Fig. 1). The right ovary was normal with no aberration to its ovarian and infundibulopelvic ligaments. The uterus was normal, and both ureters were visualized in their anatomic positions. Ectopic ovary is a rare gynecologic condition. Case reports have described ectopic ovary attached to omentum [1], colon [2], pouch of Douglas [3], inguinal canal [4], and even at the labia majora [5]. The cause of ectopic ovary is unknown, with some attributing the cause to congenital aberration. Others have proposed an acquired mechanism of torsion leading to autoamputation and subsequent reimplantation at an ectopic site. Lachman and Berman [6] divided the origin of ectopic ovary into post surgical implantation, postinflammatory implantation, and true embryological aberration. This case illustrates an interesting finding of ectopic ovary at tubal ectopic pregnancy.

The effect of ankle and knee bracing on joint stability and performance during different tasks

Braces are commonly used for prevention and treatment of ankle and knee injuries by individuals who take part in sporting activities which involve challenges to the stability of joints. However,...

Torsional Mechanics of the Left Ventricle in Patients After Surgical Repair of Tetralogy of Fallot

This study aimed to test the hypothesis that alteration of left ventricular (LV) torsional mechanics occurs in patients after repair of tetralogy of Fallot (TOF) and is associated with right ventricular (RV) volume overload and changes in LV configuration. Fifty-five TOF patients aged 19.0 ± 8.1 years and 27 age-matched healthy controls were studied. The LV and RV volumes were measured using 3-dimensional echocardiography while LV geometry was quantified by the diastolic eccentricity index (EI). The LV peak systolic torsion and systolic twisting and diastolic untwisting velocities were determined by speckle tracking. Compared with controls, patients had significantly greater RV end-systolic (P < 0.001) and diastolic (P < 0.001) volumes and LV diastolic EI (P < 0.001). In contrast, LV peak apical rotation (P < 0.001), systolic torsion (P = 0.004), systolic twisting velocity (P = 0.001), and diastolic untwisting velocity (P = 0.001) were lower in patients than in controls. For the whole cohort, RV EDV and LV diastolic EI correlated negatively with peak systolic torsion, systolic twisting velocity, and diastolic untwisting velocity (all P ≤ 0.001). Systolic torsion correlated strongly with diastolic untwisting velocity (r = 0.72, P < 0.001), while systolic twisting velocity correlated with LV ejection fraction (r = 0.3, P = 0.005). LV torsional mechanics is impaired and is negatively related to RV volume overload and LV eccentricity in patients after TOF repair.

Design and Optimization of Mechanically Resonant Torsional Spring Mechanism for Laser Light Dispersion Applications

A laser light scanning device consisting of an electronically driven mechanically resonant torsional spring-mirror system was developed for display applications. The original design suffers fatigue failure due to the repeated rotation of the torsional spring. The torsional spring design is investigated and analyzed to attain the lowest possible stress level while maintaining a constant resonant frequency. The finite element analysis model of the torsional spring was created and the stress was minimized by changing the geometrical parameters of the spring. Spring geometric optimization resulted in a maximum stress of 0.632 GPa, that is 12% reduction in stress from the original design, which should give an extended life span of 1 month for the intended application.

Stability of non-time-reversible phonobreathers

Non-time-reversible phonobreathers are nonlinear waves that can transport energy in coupled oscillator chains by means of a phase torsion mechanism. In this paper, the stability properties of these structures have been considered. An analytical study has been performed for low-coupling solutions based upon the so-called multibreather stability theorem previously developed by some of the authors (Archilla et al 2003 Physica D 180 235). A numerical analysis confirms the analytical predictions and gives a detailed picture of the existence and stability properties for arbitrary frequency and coupling.

Research on Torsional Vortex Resonance of a Streamlined Bridge Girder

The vortex resonance characteristics of one typical streamlined bridge girder are studied using surface pressure measuring technique. Based on the testing results in smooth and turbulent flows with different attack angles, the means, standard deviations, power spectra of fluctuated pressures, as well as the correlations between local and total aerodynamic forces are comprehensively analyzed, and the torsional vortex vibration mechanism is disclosed. The research results indicate that, for the vortex resonance case, the flow separation at upper and lower surfaces is more severe than that of non-vortex case. The upper surface pressure fluctuation at the middle and downstream region is most obvious, which is incurred by the flow separation at the upper surface upstream tip. At the middle and downstream region, the aerodynamic forces keep good correlations with the total forces, and they provide the major torsional moment for vortex resonance. Vortex vibration depends on both fluctuation intensity and peak location. For the vortex resonance case, the surface fluctuated pressures are locked in the same frequencies.

Torsional Mechanics of DNA Are Regulated by Small-Molecule Intercalation

Whether the bend and twist mechanics of DNA molecules are coupled is unclear. Here, we report the direct measurement of the resistive torque of single DNA molecules to study the effect of ethidium bromide (EtBr) intercalation and pulling force on DNA twist mechanics. DNA molecules were overwound and unwound using recently developed magnetic tweezers where the molecular resistive torque was obtained from Brownian angular fluctuations. The effect of EtBr intercalation on the twist stiffness was found to be significantly different from the effect on the bend persistence length. The twist stiffness of DNA was dramatically reduced at low intercalator concentration (<10 nM); however, it did not decrease further when the intercalator concentration was increased by 3 orders of magnitude. We also determined the dependence of EtBr intercalation on the torque applied to DNA. We propose a model for the elasticity of DNA base pairs with intercalated EtBr molecules to explain the abrupt decrease of twist stiffness at low EtBr concentration. These results indicate that the bend and twist stiffnesses of DNA are independent and can be differently affected by small-molecule binding.

Kinetics of Left Ventricular Strains and Torsion During Incremental Exercise in Healthy Subjects

Background— The dynamics of systolic and diastolic strains and torsional mechanics of the left ventricle (LV) and their relation to diastolic filling never have been evaluated at various exercise intensities. Methods and Results— Speckle tracking echocardiography was performed in 20 healthy sedentary subjects at rest and during a progressive submaximal exercise test at 20%, 30%, and 40% of maximal aerobic power. LV twist increased progressively with exercise intensity (10.5±3.2 to 15.8±4.5°; P &lt;0.001), whereas longitudinal strain remained unchanged after the first workload, underlining the key role of torsional reserve in systolic-diastolic coupling during exercise. The increase in diastolic untwisting (−88.7±34.2 to −182.9±53.5 deg · s −1 ; P &lt;0.01) was correlated to enhanced systolic twist ( R =0.61; P &lt;0.001), and its magnitude of increase was significantly higher compared to diastolic longitudinal and circumferential strain rates (119±64% versus 65±44% and 57±24%, respectively), emphasizing its contribution to diastolic filling. The timing of peak untwisting and the chronology of diastolic mechanical events were unchanged during effort. Untwisting was driven mainly by apical rotation and determined mitral opening and isovolumic relaxation time ( R =0.47 and 0.61, respectively; P &lt;0.001), whereas basal rotation and longitudinal and circumferential diastolic strain rates were major determinants of increased early diastolic filling ( R =0.64, 0.79, and 0.81, respectively; P &lt;0.001). Conclusions— The use of speckle tracking echocardiography gives new insights into physiological adaptive LV mechanics during incremental exercise in healthy subjects, underlining the key role of torsional mechanics. It might be useful to better understand the mechanisms of diastolic dysfunction and exercise intolerance in various pathological conditions.

Experiment and Simulation of Electromagnetic Stiffness for Stepper Motor

Electromagnetic stiffness is an important parameter of stepper motor. It impacts obviously on system natural frequency. In this paper, the torsional vibration mechanism of stepper motor rotor caused by electromagnetic stiffness is studied and the mathematical formula for electromagnetic stiffness is established derived from stepper motor mathematical models. We simulate and experiment on stepper motor with parameters in the paper. Simulation value and experiment value of the electromagnetic stiffness are consistence with the numerical one. So it verifies the existence of electromagnetic stiffness, which provides a basis for researching on frequency variation of motor dragging flexible load.

Beyond the Chemiosmotic Theory: Analysis of Key Fundamental Aspects of Energy Coupling in Oxidative Phosphorylation in the Light of a Torsional Mechanism of Energy Transduction and ATP Synthesis—Invited Review Part 1

In Part 1 of this invited article, we consider the fundamental aspects of energy coupling in oxidative phosphorylation. The central concepts of the chemiosmotic theory are re-examined and the major problems with its experimental verification are analyzed and reassessed from first principles. Several of its assumptions and interpretations (with regard, for instance, to consideration of the membrane as an inert barrier, the occurrence of energy transduction at thermodynamic equilibrium, the completely delocalized nature of the protonmotive force, and the notion of indirect coupling) are shown to be questionable. Important biological implications of this analysis for molecular mechanisms of biological energy transduction are enumerated. A fresh molecular mechanism of the uncoupling of oxidative phosphorylation by classical weak acid anion uncouplers and an adequate explanation for the existence of uncoupler-resistant mutants (which until now has remained a mystery) has been proposed based on novel insights arising from a new torsional mechanism of energy transduction and ATP synthesis.

Beyond the Chemiosmotic Theory: Analysis of Key Fundamental Aspects of Energy Coupling in Oxidative Phosphorylation in the Light of a Torsional Mechanism of Energy Transduction and ATP Synthesis—Invited Review Part 2

The core of this second article shows how logical errors and inconsistencies in previous theories of energy coupling in oxidative phosphorylation are overcome by use of a torsional mechanism and the unified theory of ATP synthesis/hydrolysis. The torsional mechanism is shown to satisfy the pioneering and verified features of previous mechanisms. A considerable amount of data is identified that is incompatible with older theories but is now explained in a logically consistent and unified way. Key deficiencies in older theories are pinpointed and their resolution elucidated. Finally, major differences between old and new approaches are tabulated. The new theory now provides the elusive details of energy coupling and transduction, and allows several novel and experimentally verifiable predictions to be made and a considerable number of applications in nanotechnology, energy conversion, systems biology, and in health and disease are foreseen.

Possible mechanisms of left ventricular torsion evaluated by cardioreparative effects of telmisartan in patients with hypertension

Left ventricular (LV) torsion may be an important component of normal LV systolic function. However, its mechanics remain unresolved. Two-dimensional (2-D) strain imaging is increasingly used to quantify LV torsion in the clinical setting. Telmisartan has cardioreparative effects, including attenuation of subendocardial myocardial fibrosis and improvement of LV remodelling. To clarify the mechanisms of LV torsion, in the present study, we evaluated changes in LV longitudinal deformation and torsion after medication with telmisartan using 2-D strain imaging in patients with hypertension (HT). Telmisartan (20-40 mg daily) was administered to 37 previously untreated patients with HT. Two-dimensional strain echocardiography was performed after medication had been continued for 1-2 months with normal values for blood pressure (BP) (phase I) and for 12 months (phase II). In the phase II, relative LV wall thickness, LV mass index, LV torsion, and torsional rate were reduced, whereas the mean peak systolic longitudinal strain and strain rate were increased, compared to the phase I. LV torsion correlated well with relative LV wall thickness, but not LV mass index. Our results obtained from cardioreparative effects of telmisartan suggested that LV torsion is associated with systolic longitudinal deformation related to subendocardial myocardial fibrosis, and/or LV concentric hypertrophy-related difference in torques between the subendocardial and subepicardial sides.

Foot and Ankle Injuries in the Barefoot Sports

Playing sports barefoot has been contested since the very beginnings of athletic competition. Even today, some data suggest that shoes may limit the adaptive pronation that occurs after footstrike during running gait. This pronation likely protects runners from injury. Boardsport participants who perform their sports barefoot on the water seem to be at risk for foot and ankle injuries. The high-impact forces in gymnastics place participants at risk for foot and ankle injuries, as well. Swimming and diving have a low rate of foot and ankle injuries. The risk of ankle sprain in beach volleyball, which is played barefoot, seems to be lower than that for indoor volleyball, played wearing shoes. Martial arts place competitors at risk for injuries to the foot and ankle from torsional and impact mechanisms. Athletes who hope to return to barefoot competition after injury should perform their rehabilitation in their bare feet.

Alteration in Left Ventricular Strains and Torsional Mechanics After Ultralong Duration Exercise in Athletes

Numerous studies have reported evidence of cardiac injury associated with transient left ventricular (LV) systolic and diastolic dysfunction after prolonged and strenuous exercise. We used 2D ultrasound speckle tracking imaging to evaluate the effect of an ultralong-duration exercise on LV regional strains and torsion. We speculated that systolic dysfunction after exercise is associated with depressed LV strains and torsion, and diastolic dysfunction results from decreased and delayed untwisting, a key factor of LV suction and early filling. Twenty-three triathletes underwent conventional and speckle tracking imaging echocardiography at rest before and immediately after an ultralong distance triathlon. Measurements included LV longitudinal, circumferential and radial strains, LV rotations, and LV torsion. After the race, LV systolic dysfunction was characterized by a decrease in LV longitudinal, radial, and circumferential strains, especially for apical radial strains (44.6+/-15.1% versus 31.1+/-13.8%, P<0.001). Peak torsion was slightly decreased (8.3+/-5.1 degrees versus 6.4+/-3.9 degrees , respectively, P=0.09) and significantly delayed (91+/-18% versus 128+/-31% of systolic duration, P<0.001) beside end-ejection. Peak untwisting was also depressed and delayed beside isovolumic relaxation. This study documented major alterations in cardiac strains and torsion after an ultralong distance triathlon. LV systolic strains were depressed but not delayed, whereas twisting was decreased and delayed. This altered pattern hampered the rapid untwisting during isovolumic relaxation phase, reducing LV diastolic suction and early filling.

The new unified theory of ATP synthesis/hydrolysis and muscle contraction, its manifold fundamental consequences and mechanistic implications and its applications in health and disease.

Complete details of the thermodynamics and molecular mechanisms of ATP synthesis/hydrolysis and muscle contraction are offered from the standpoint of the torsional mechanism of energy transduction and ATP synthesis and the rotation-uncoiling-tilt (RUT) energy storage mechanism of muscle contraction. The manifold fundamental consequences and mechanistic implications of the unified theory for oxidative phosphorylation and muscle contraction are explained. The consistency of current mechanisms of ATP synthesis and muscle contraction with experiment is assessed, and the novel insights of the unified theory are shown to take us beyond the binding change mechanism, the chemiosmotic theory and the lever arm model. It is shown from first principles how previous theories of ATP synthesis and muscle contraction violate both the first and second laws of thermodynamics, necessitating their revision. It is concluded that the new paradigm, ten years after making its first appearance, is now perfectly poised to replace the older theories. Finally, applications of the unified theory in cell life and cell death are outlined and prospects for future research are explored. While it is impossible to cover each and every specific aspect of the above, an attempt has been made here to address all the pertinent details and what is presented should be sufficient to convince the reader of the novelty, originality, breakthrough nature and power of the unified theory, its manifold fundamental consequences and mechanistic implications, and its applications in health and disease.

Modulation of the Packaging Reaction of Bacteriophage T4 Terminase by DNA Structure

Bacteriophage terminases package DNA through the portal ring of a procapsid during phage maturation. We have probed the mechanism of the phage T4 large terminase subunit gp17 by analyzing linear DNAs that are translocated in vitro. Duplex DNAs of random sequence from 20 to 500 bp were efficiently packaged. Dye and short, single-stranded end extensions were tolerated, whereas 20-base extensions, hairpin ends, 20-bp DNA–RNA hybrid, and 4-kb dsRNA substrates were not packaged. Molecules 60 bp long with 10 mismatched bases were translocated; substrates with 20 mismatched bases, a related D-loop structure, or ones with 20-base single-strand regions were not. A single nick in 100- or 200-bp duplexes, irrespective of location, reduced translocation efficiency, but a singly nicked 500-bp molecule was packaged as effectively as an unnicked control. A fluorescence-correlation-spectroscopy-based assay further showed that a 100-bp nicked substrate did not remain stably bound by the terminase–prohead. Taken together, two unbroken DNA strands seem important for packaging, consistent with a proposed torsional compression translocation mechanism.

Rat disc torsional mechanics: effect of lumbar and caudal levels and axial compression load

Background context Rat models with altered loading are used to study disc degeneration and mechano-transduction. Given the prominent role of mechanics in disc function and degeneration, it is critical to measure mechanical behavior to evaluate changes after model interventions. Axial compression mechanics of the rat disc are representative of the human disc when normalized by geometry, and differences between the lumbar and caudal disc have been quantified in axial compression. No study has quantified rat disc torsional mechanics. Purpose Compare the torsional mechanical behavior of rat lumbar and caudal discs, determine the contribution of combined axial load on torsional mechanics, and compare the torsional properties of rat discs to human lumbar discs. Study design Cadaveric biomechanical study. Methods Cyclic torsion without compressive load followed by cyclic torsion with a fixed compressive load was applied to rat lumbar and caudal disc levels. Results The apparent torsional modulus was higher in the lumbar region than in the caudal region: 0.081±0.026 (MPa/°, mean±SD) for lumbar axially loaded; 0.066±0.028 for caudal axially loaded; 0.091±0.033 for lumbar in pure torsion; and 0.056±0.035 for caudal in pure torsion. These values were similar to human disc properties reported in the literature ranging from 0.024 to 0.21 MPa/°. Conclusions Use of the caudal disc as a model may be appropriate if the mechanical focus is within the linear region of the loading regime. These results provide support for use of this animal model in basic science studies with respect to torsional mechanics.

Disparate Patterns of Left Ventricular Mechanics Differentiate Constrictive Pericarditis From Restrictive Cardiomyopathy

The purpose of this study was to compare the longitudinal, circumferential, and radial mechanics of the left ventricle (LV) in patients with constrictive pericarditis (CP) and restrictive cardiomyopathy (RCM). Diastolic dysfunction in CP is related to epicardial tethering and pericardial constraint, whereas in RCM it is predominantly characterized by subendocardial dysfunction. Assessment of variations in longitudinal and circumferential deformation of LV might be useful to distinguish these 2 conditions. Longitudinal, radial, and circumferential mechanics of the LV were quantified by 2-dimensional speckle tracking of B-mode cardiac ultrasound images in 26 patients with CP, 19 patients with RCM, and 21 control subjects. In comparison with control subjects, patients with CP had significantly reduced circumferential strain (base; -16 +/- 6% vs. -9 +/- 6%; p < 0.016), torsion (3 +/- 1 degrees /cm vs. 1 +/- 1 degrees /cm; p < 0.016), and early diastolic apical untwisting velocities (E(r); 116 +/- 62 degrees /s vs. -36 +/- 50 degrees /s; p < 0.016), whereas longitudinal strains, displacement, and early diastolic velocities at the LV base (E(m)) were similar to control subjects. In contrast, patients with RCM showed significantly reduced longitudinal displacement (base; 14.7 +/- 2.5 cm vs. 9.8 +/- 2.8 cm; p < 0.016) and E(m) (-8.7 +/- 1.3 cm/s vs. -4.4 +/- 1.1 cm/s; p < 0.016), whereas circumferential strain and E(r) were similar to those of control subjects. For differentiation of CP from RCM, the area under the curve was significantly higher for E(m) in comparison with E(r) (0.97 vs. 0.76, respectively; p = 0.01). After pericardiectomy, there was a significant decrease in longitudinal early diastolic LV basal myocardial velocities (7.4 cm/s vs. 6.8 cm/s; p = 0.023). Circumferential strain, torsion, and E(r), however, remained unchanged. Deformation of the LV is constrained in the circumferential direction in CP and in the longitudinal direction in RCM. Subsequent early diastolic recoil of LV is also attenuated in each of the 2 directions, respectively, uniquely differentiating the abnormal diastolic restoration mechanics of the LV seen in CP and RCM.

Abstract 2487: Torsional and Reverse Rotational Mechanics of the Left Ventricular Apex Is Abnormal in Patients with Type 2 Diabetes Mellitus Independent of Presence of Hypertension, Left Ventricular Hypertrophy, Elevated Filling Pressures and Left Atrial Volume

Background : Diastolic dysfunction (DD) is common in patients with Type 2 DM even in the absence of HTN and LVH. We tested whether apical rotational mechanics offered any additional insights into DD in DM over conventional echo-Doppler measures. Methods: We studied 4 groups : 12 normals (wall thickness-WT 0.9±0.1cm); 17 patients with DM (WT 1.0±0.1cm, HbA1c 7±1%, BP 128±4/68±5 mmHg); 16 patients with DM +HTN (WT 0.9±0.1cm, HbA1c 7±1%, BP 134±23/72±18 mmHg); and 20 patients with DM+HTN+LVH (WT 1.4±0.2cm, HbA1c 7±4%, BP 135±13/76±9mmHg). All patients had normal LVEF and mitral E/A ratio. SAX of the LV apex and base were obtained. Velocity Vector Imaging (Siemens, CA) was used to measure: Longitudinal myocardial velocity (LMV, cm/sec) and strain (LS,%); Apical rotation velocity (ARV, cm/sec)and reverse rotation velocity(ARRV, cm/sec); Apical rotation (AR, degree) and LV torsion-LVTOR (degree/cm, and Circumferential (CS,%) and Radial strains (RS,%). Results: Figure shows LVTOR and % reduction in ARRV data. All other data will be presented. Thus, LV torsion is increased in DM alone or DM+HTN (-LVH) groups. But ARRV is reduced by ~ 20% in these groups even with relatively normal E/E’ ratio and LAVI. In the DM+HTN+LVH group, E/E’ and LAVI are increased and apical rotational mechanics resemble the same spectrum as the above groups but are more severe (~25% reduction in ARRV). Thus, reduction in ARRV is a marker of early DD in DM even in the absence of LVH . Conclusions: Apical rotational mechanics is more sensitive than conventional echo-Doppler measures to identify myocardial DD in type 2 DM even in the presence of normal E/A ratio, LAVI and LVEF, and in the absence of HTN and/or LVH.