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At least 973 records · Page 54Linked to original sources
PubMed2025

Deep Characterisation of Circulating Torque Teno Virus DNA Load in Crohn's Disease Patients.

Torque teno virus (TTV) DNA load in plasma is suggested as a marker for immunosuppression post-transplantation. Crohn's disease (CD) arises from genetic susceptibility, environmental factors, and dysbiosis, causing immune responses. This study examines TTV DNA load in CD patients in remission and its correlation with relapse. Using quantitative real-time polymerase chain reaction (PCR) and metagenomic analysis, the dynamic of plasma TTV DNA load was analyzed from a cohort of CD patients (n = 39) over 1 year and compared with controls (n = 49). At inclusion, TTV DNA was significantly higher in CD patients compare to control (Median [IQR]: 3.27 [2.43-3.67] and 2.05 [1.28-2.80] Log copies/mL, p = 0.0004). Plasma TTV DNA load failed to predict disease relapse in CD patients. Augmented plasma TTV DNA levels in CD patients correlated with diminished circulating CD3 + T cells and especially CD4 + T cells. No preferential representation of TTV subspecies or Anelloviridae genera was detected in CD patients' plasma. This study revealed elevated TTV DNA levels in CD patients' plasma compared to healthy controls, underscoring the intriguing potential of TTV blood sampling as a biomarker in CD.

Humans↗
PubMed2007

Genetic relationship of Torque Teno virus (TTV) between humans and camels in United Arab Emirates (UAE).

Torque Teno Virus (TTV) species-cross infection has been documented. However, the genetic relationship between human and animal TTV remains uncertain. In this study, genotypic characterization of TTV in different Camel specimens from the United Arab Emirates (UAE) was undertaken for comparison with human UAE TTV. A total of 56 specimens: 34 sera, 14 raw, and 8 pasteurized milk samples were tested for TTV. The results showed that the rate of infection was, 38.2% (13/34), 35.7% (5/14), and 100% (8/8), for the samples of sera, raw, and pasteurized milk respectively. The 5'untranslated region (5'UTR) of 23 clones that were generated from PCR products amplified from Camel samples (three sera, three raw, and two pasteurized milk samples) were subjected to sequence analysis. The camel TTV clones were classified as genotype 11 (47.8%), group 5 (43.5%), and SENV-H or genotype 16 (8.7%) which are among the predominant genotypes found in humans in the UAE. Phylogenetic analysis of representative sequences revealed that the similarity between isolates from camels and humans is 92%-97% for the same genotypes. The data lead to the conclusion that camels and humans share a common source of TTV infection in the UAE.

Animals↗
PubMed1996

Concept and development of a measuring system for in vivo recording of orthodontically applied forces and torques in the multiband technique. Part I.

The cause of tooth movement with a multiband or multibracket appliance is the force system in the bracket, which is generated by an archwire and transmitted by a bracket to the respective tooth. Continuous arch wires are, from the biomechanical point of view, a statically multiply undetermined system. Quantitative determination of the forces and torques acting at the individual teeth, and thus observance of a non-critical level of applied forces, is therefore extremely problematic in practice, the force is applied by the orthodontist more or less "intuitively" on the basis of recommendations evolved in theory and in vitro. The measuring technique presented in this paper is designed to permit these force systems to be recorded in vivo for the first time, allowing account to be taken of the individual situation "tooth-periodontium-bone". Evolvement of an appropriate measuring principle was followed by development of the individual components of the measuring system. The results of the subsequent initial in vitro test series offer the prospect of successful clinical application.

Dental Stress Analysis↗
PubMed1996

Effect of the underwater torque on the energy cost, drag and efficiency of front crawl swimming.

Underwater torque (T') is defined as the product of the force with which the swimmer's feet tend to sink times the distance between the feet and the centre of volume of the lungs. It has previously been shown that experimental changes of T', obtained by securing around the swimmer's waist a plastic tube filled, on different occasions, with air, water or 2-kg lead, were accompanied by changes in the energy cost of swimming per unit of distance (Cs) at any given speed. The aim of this study was to investigate whether the observed increases of Cs with T' during front crawl swimming were due to an increase of active body drag (Db), a decrease of drag efficiency (eta /d) or both. The effect of experimental changes of T' on Cs, Db and eta /d were therefore studied on a group of eight male elite swimmers at two submaximal speeds (1.00 and 1.23 m.s-1). To compare different subjects and different speeds, the individual data for Cs, Db, eta /d and T' were normalized dividing them by the corresponding individual averages. These were calculated from all individual data (of Cs, Db, eta /d and T') obtained from that subject at that speed. It was found that, between the two extremes of this study (tube filled with air and with 2-kg lead), T' increased by 73% and that Cs, Db and eta /d increased linearly with T'. The increase of Cs between the two extremes was intermediate (approximately 20%) between that of Db (approximately 35%) and of eta /d (approximately 16%). Thus, the actual strategy implemented by the swimmers to counteract T', was to tolerate a large increase of Db. This led also to a substantial (albeit smaller) increase of r/d, the effect of which was to reduce the increase of Cs that would otherwise have occurred.

Adult↗
PubMed2001

Root resorptions in upper first premolars after application of continuous torque moment. Intra-individual study.

MATERIAL AND METHOD: With the purpose of investigating the occurrence, localization and extension of possible root resorptions after fixed appliance treatment with a continuous torque force, 28 upper first premolars orthodontically indicated for extraction from 14 patients were analyzed by scanning electron microscopy. Tooth movement was carried out with continuous moments of different magnitudes (300 cNmm, and 600 cNmm), using a biomechanical model with superelastic wires (stainless steel-NiTi-SE), which was specially designed and individually calibrated. The teeth were divided into one control group with four premolars (non-moved) from two patients, and two experimental groups (300 cNmm and 600 cNmm respectively) with six patients each. Each group was distributed intra-individually as follows: the right first premolar of six patients was extracted after 1 week of movement, the left first premolars were removed after 2, 3 and 4 weeks. After extraction, teeth were fixed, treated with 2% sodium hypochlorite solution for 6 hours in order to remove the organic tissue components, dehydrated, and metal-coated in a Balzers SCD 050 apparatus. RESULTS: The analysis in a scanning electron microscope (Jeol 6100, at 10-15 kV) revealed many resorption lacunae in the root surface, mainly on the lingual side in the apical third of the roots. Resorption processes were also observed on the buccal root surface in the cervical third. All experimental teeth showed resorption areas. Teeth which had been moved for a longer time period and with a higher magnitude of applied moments showed a higher degree of root resorption in width as well as in depth. Higher magnitude of moments produced exposure of root dentine, evidencing pronounced root resorption.

Bicuspid↗
PubMed2006

Adjustments of prehension synergies in response to self-triggered and experimenter-triggered load and torque perturbations.

Humans are known to show anticipatory adjustments in the grip force prior to a self-generated or predictable action or perturbation applied to a hand-held object. We investigated whether humans can also adjust covariation of individual finger forces (multi-finger synergies) prior to self-triggered perturbations. To address this issue, we studied adjustments in multi-digit synergies associated with applied load/torque perturbations while the subjects held a customized handle steadily. The main hypothesis was that the subjects would be able to demonstrate the phenomenon of anticipatory covariation, that is changes in covariation patterns among digit forces and moments of force in anticipation of a perturbation, but only when the perturbation was triggered by the subjects themselves. Based on the principle of superposition (decoupled grasping force and resultant torque control), we also expected to see different adjustments in indices of multi-digit synergies stabilizing the total gripping force and the total moment of force. The task for the subjects (n = 8) was to return the initial handle position as quickly as possible after a perturbation, which consisted of removing one of three loads hanging from the handle. There were six experimental conditions: two types of perturbations (self-triggered and experimenter-triggered) by three positions of the load (left, center, and right). Three-dimensional forces and moments of force recorded from each digit contact were used for the analysis. Indices of covariation among digit forces and among moments of force, previously employed for studying motor synergies, were computed across trials. Positive values of the indices reflected negative covariations of individual digit forces and moments of force (their inter-compensatory changes) to stabilize the total force and moment acting on the handle. In steady-state conditions, subjects showed strong positive indices for both digit forces and digit moments. Under the self-triggered conditions, changes in the indices of digit force and moment covariation were seen about 150 ms prior to the perturbation, while such changes were observed only after the perturbation under the experimenter-triggered conditions. Immediately following a perturbation, the indices of force and moment covariation rapidly changed to negative revealing the lack of inter-compensation among the individual digit forces and moments. Later, both indices showed a recovery to positive values; the recovery was faster in the self-triggered conditions than in the experimenter-triggered ones. During the steady-state phase after the perturbation, the indices of force and moment covariation decreased and increased, respectively, as compared to their values during the steady-state phase prior to the perturbation. We conclude that humans are able to adjust multi-digit synergies involved in prehensile tasks in anticipation of a self-triggered perturbation. These conclusions speak against hypotheses on the organization of multi-element actions based on optimal control principles. Different changes in the indices of force and moment covariation after a perturbation corroborate the principle of superposition. We discuss relations of anticipatory covariation to anticipatory postural adjustments.

Adult↗
PubMed2004

The acute effects of static stretching on peak torque, mean power output, electromyography, and mechanomyography.

The purpose of this study was to examine the acute effects of static stretching on peak torque (PT), the joint angle at PT, mean power output (MP), electromyographic (EMG) amplitude, and mechanomyographic (MMG) amplitude of the vastus lateralis (VL) and rectus femoris (RF) muscles during maximal, voluntary concentric isokinetic leg extensions at 60 and 240 degrees x s(-1) of the stretched and unstretched limbs. Twenty-one volunteers [mean age (SD) 21.5 (1.3) years] performed maximal, voluntary concentric isokinetic leg extensions for the dominant and non-dominant limbs at 60 and 240 degrees x s(-1). Surface EMG (muVrms) and MMG (mVrms) signals were recorded from the VL and RF muscles during the isokinetic tests. PT (Nm), the joint angle at PT, and MP (W) were calculated by a dynamometer. Following the initial isokinetic tests, the dominant leg extensors were stretched using four static stretching exercises. After the stretching, the isokinetic tests were repeated. PT decreased (P< or =0.05) from pre- to post-stretching for the stretched limb at 60 and 240 degrees x s(-1) and for the unstretched limb at 60 degrees x s(-1). EMG amplitude of the VL and RF also decreased (P< or =0.05) from pre- to post-stretching for the stretched and unstretched limbs. There were no stretching-induced changes (P>0.05) for the joint angle at PT, MP, or MMG amplitude. These findings indicated stretching-induced decreases in force production and muscle activation. The decreases in PT and EMG amplitude for the unstretched limb suggested that the stretching-induced decreases may be due to a central nervous system inhibitory mechanism.

Adult↗
PubMed2005

Regularity in an environment produces an internal torque pattern for biped balance control.

In this paper, we present a control method for achieving biped static balance under unknown periodic external forces whose periods are only known. In order to maintain static balance adaptively in an uncertain environment, it is essential to have information on the ground reaction forces. However, when the biped is exposed to a steady environment that provides an external force periodically, uncertain factors on the regularity with respect to a steady environment are gradually clarified using learning process, and finally a torque pattern for balancing motion is acquired. Consequently, static balance is maintained without feedback from ground reaction forces and achieved in a feedforward manner.

Biomechanical Phenomena↗
PubMed2006

Maximal dynamic grip force and wrist torque: the effects of gender, exertion direction, angular velocity, and wrist angle.

The objective of this study was to examine the effects of gender, exertion direction, angular velocity and wrist angle on simultaneous grip force and wrist torque under the isokinetic condition. The study used 20 participants (10 males and 10 females) and included 6 angular velocities (15, 30, 45, 60, 75, and 90 degrees /s) and 2 wrist exertion directions (flexion and extension) over the wrist range of motion of 70 degrees flexion to 60 degrees extension in 5 degrees increments. Similar to other studies, males and flexion exertion produced larger forces than females and extension exertion, respectively. However, the largest forces were generated at near extreme flexion of the wrist and the dependent variable of angular velocity was not practically significant. These results can contribute to the evaluation of cumulative trauma syndromes, but there is a need for more research on the dynamic measures of the hand and wrist complex and for standard development for dynamic force measurement.

Adult↗
PubMed2005

Rotary torque produced by proton motive force in FoF1 motor.

We have attempted direct observation of the light-driven rotation of a FoF(1)-ATP motor. The FoF(1)-ATP motor was co-reconstituted by the deletion-delta subunit of FoF(1)-ATP synthase with bacteriorhodopsins (BRs) into a liposome. The BR converts radiation energy into electrochemical gradient of proton to drive the FoF(1)-ATP motor. Therefore, the light-driven rotation of FoF(1)-ATP motor has been directly observed by a fluorescence microscopy using a fluorescent actin filament connected to beta-subunit as a marker of its orientation. The rotational torque value of the Fo motor was calculated as 27.93+/-1.88pNnm. The ATP motor is expected to be a promising rotary molecular motor in the development of nanodevices.

Actin Cytoskeleton↗
PubMed2006

Torque teno virus (TTV) is highly prevalent in the European wild boar (Sus scrofa).

The present study represents the first survey of Torque teno virus (TTV) prevalence in European wild boar (Sus scrofa). The prevalence of two distinct TTV genogroups in 178 Spanish wild boar sera from different geographic regions, management conditions, gender and age was determined by a nested PCR method. The overall prevalence of TTV genogroups was 84% (58% for genogroup 1 and 66% for genogroup 2), and differences between genogroup prevalence were observed depending on the geographical region analysed. Significantly higher prevalence for TTV genogroup 2 was found in fenced managed wild boar, juvenile animals and females. No other significant differences in TTV genogroup prevalence were observed. The phylogenetic analysis of nucleotide sequences obtained from the untranslated region of selected samples revealed that the same TTV genogroups are infecting wild boar and domestic pig. The results indicate that TTV is apparently ubiquitous in European wild boar populations.

Age Factors↗
PubMed2005

One-year monthly monitoring of Torque teno virus (TTV) in wastewater treatment plants in Japan.

Torque teno virus (TTV) is a novel hepatitis virus which is considered to be transmitted by the fecal-oral route. Wastewater samples were collected monthly from eight wastewater treatment plants in Japan for 1 year, from July 2003 to June 2004, and tested for the presence of TTV by TaqMan PCR. TTV was detected in 97% (93/96) of influent samples, implying that TTV is epidemic in Japan. TTV was also isolated in 18% (17/96) of secondary effluent samples before chlorination and in 24% (23/95) of final effluent samples after chlorination. There was no significant difference between the concentration of total coliform in TTV-positive final effluents and that in TTV-negative final effluents, which indicates that total coliform cannot be used as an indicator of TTV. No TTV was detected in 24 effluents for reuse from two wastewater treatment plants using sand filtration and ozonation.

Chlorine↗
PubMed1996

Torque-generating units of the bacterial flagellar motor step independently.

Measurements of the variance in rotation period of tethered cells as a function of mean rotation rate have shown that the flagellar motor of Escherichia coli is a stepping motor. Here, by measurement of the variance in rotation period as a function of the number of active torque-generating units, it is shown that each unit steps independently.

Bacterial Proteins↗
PubMed2001

How do non-muscular torques contribute to the kinetics of postural recovery following a support surface translation?

The common platform translation paradigm used in balance control studies employs a disturbance event that applies non-muscular forces to the body for the duration of the disturbance. Previous research has explored the process of constructing the balance recovery by considering these perturbations to be trigger events, not events with an ongoing force application timeline. The purpose of this study was to quantify the effect of muscular and non-muscular torques on post-perturbation balance with particular interest in the role of the external perturbation in balance recovery. Five young adult males experienced backward translations of the support surface at three different speeds. Integration intervals were defined for each segment and angular impulses were calculated for a period of increasing angular momentum (destabilization), and a period of decreasing angular momentum (restabilization). Destabilization of distal segments was primarily due to impulse generated by the motion of the support surface. For the trunk, however, muscle and motion-dependent sources contributed most to increasing momentum. Restabilization of distal segments was achieved by muscle and platform impulses while trunk restabilization was achieved by muscle and motion-dependent terms in opposition to gravity. Increased platform speed resulted in increased muscular contribution only in the control of the trunk, while demand on distal musculature decreased with change in platform speed as the platform contribution to restabilization increased in these segments. Therefore, impulses from non-muscular sources, including the perturbation itself, are significant modifiers of the response to balance disturbances and must be accounted for in balance research.

Adult↗
PubMed1999

Apparatus for measuring and perturbing shoulder and elbow joint positions and torques during reaching.

Visually guided reaching movements by monkeys has become an important paradigm for examining the function of various sensory and motor areas of the brain. However, a major problem with interpreting neural discharge during this motor task has been the difficulty to quantify and manipulate the mechanics of movement. To address this problem, a new experimental facility has been developed to allow neural recordings in a monkey while it makes movements with a mechanical linkage attached to its arm. The device (KINARM) has hinge joints aligned with the monkey's shoulder and elbow and allows the monkey to make arm movements in the horizontal plane. Custom-made fibreglass braces attach the linkage to the monkey's forearm and arm. Motors attached to the mechanical linkage provide angular position of the joints and apply torques either to the shoulder or elbow, or both. The KINARM is used in concert with a computer projection system that provides virtual targets in the plane of the arm. Preliminary results illustrate the ability of a monkey to perform a variety of multi-joint motor tasks under various static and dynamic loads.

Animals↗
PubMed1998

Rectangular wire and third-order torque: a new perspective.

The Differential Straight Arch technique, more commonly known as "Tip-Edge" (TP Orthodontics Inc.), uses a modified edgewise type bracket to allow differential tooth movement. As bracketed teeth incline toward their finishing positions, the geometry of the arch wire slot causes the vertical slot dimension available to the arch wire to increase. Advantage has been taken of this facility, to evolve an entirely new torquing system for final finishing, during the root correction phase. Instead of increasing rectangular arch wire size to fit the arch wire slot, as with conventional edgewise brackets, the Tip-Edge method reduces the vertical arch wire slot dimension to achieve a precise, three-dimensional relationship to a full-sized rectangular arch wire. The active component is provided by auxiliary springs. The method, which awaits mathematical analysis, is described and illustrated with two case reports.

Adolescent↗
PubMed2005

Torque-actuated valves for microfluidics.

This paper describes torque-actuated valves for controlling the flow of fluids in microfluidic channels. The valves consist of small machine screws (> or =500 microm) embedded in a layer of polyurethane cast above microfluidic channels fabricated in poly(dimethylsiloxane) (PDMS). The polyurethane is cured photochemically with the screws in place; on curing, it bonds to the surrounding layer of PDMS and forms a stiff layer that retains an impression of the threads of the screws. The valves were separated from the ceiling of microfluidic channels by a layer of PDMS and were integrated into channels using a simple procedure compatible with soft lithography and rapid prototyping. Turning the screws actuated the valves by collapsing the PDMS layer between the valve and channel, controlling the flow of fluids in the underlying channels. These valves have the useful characteristic that they do not require power to retain their setting (on/off). They also allow settings between "on" and "off" and can be integrated into portable, disposable microfluidic devices for carrying out sandwich immunoassays.

Immunoassay↗
PubMed1999

The gamma-subunit rotation and torque generation in F1-ATPase from wild-type or uncoupled mutant Escherichia coli.

The rotation of the gamma-subunit has been included in the binding-change mechanism of ATP synthesis/hydrolysis by the proton ATP synthase (FOF1). The Escherichia coli ATP synthase was engineered for rotation studies such that its ATP hydrolysis and synthesis activity is similar to that of wild type. A fluorescently labeled actin filament connected to the gamma-subunit of the F1 sector rotated on addition of ATP. This progress enabled us to analyze the gammaM23K (the gamma-subunit Met-23 replaced by Lys) mutant, which is defective in energy coupling between catalysis and proton translocation. We found that the F1 sector produced essentially the same frictional torque, regardless of the mutation. These results suggest that the gammaM23K mutant is defective in the transformation of the mechanical work into proton translocation or vice versa.

Actins↗