Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “Traction”

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 523 records · Page 29Linked to original sources
PubMed2005

Temporary Erb-Duchenne palsy without shoulder dystocia or traction to the fetal head.

BACKGROUND: Although many retrospective studies report that brachial plexus palsies occur after vaginal delivery in the absence of recorded shoulder dystocia, there are no known prospective reports by a treating clinician (PubMed, English language only, 1952-June 2004, search terms: shoulder dystocia, nonshoulder dystocia, obstetric brachial plexus injury, Erb's palsy, Erb-Duchenne palsy, spontaneous vaginal delivery). CASE: A multiparous patient presented with a birth plan requesting that the baby be allowed to deliver on its own, without traction on the head and without suctioning. Although induced at term for elevated blood pressure, the otherwise healthy patient experienced a normal labor with a 30-minute second stage. At delivery, which was videotaped by the father, the fetal head presented over an intact perineum in a right-occiput-anterior position. Without traction, the anterior shoulder delivered spontaneously with the next contraction and Valsalva, followed by the posterior shoulder. The trunk followed routinely. The average-weight for gestational age neonate exhibited an Erb-Duchenne palsy of the right (posterior) arm that resolved on the fourth day of life. CONCLUSION: Temporary Erb-Duchenne palsy can occur in the posterior arm after normal labor and spontaneous delivery without shoulder dystocia or traction on the fetal head.

Adult↗
PubMed1989

Scanning electron microscopy comparing exclamation mark hairs in alopecia areata with normal hair fibres, mechanically broken by traction.

A scanning electron microscope was used to compare the distal ends of exclamation mark hairs from alopecia areata patients with the fracture surface of normal hair fibres, mechanically broken by traction. The exclamation mark hairs shows minimal damage to the cuticular cell pattern of the hair shaft. Where the cuticle was absent, cortex and medulla showed low-density features fanning out into a fringe-like structure at the distal ends. The fracture surfaces of normal hair fibres, mechanically broken by traction showed a markedly abnormal cuticular scale pattern, whereas the features of cortical and medullary tissue were normal. These morphological differences between the fracture surface of exclamation mark hairs and normal hair fibres, mechanically broken by traction, may enhance our understanding of the pathogenesis of alopecia areata.

Adult↗
PubMed1992

Experimental traction injuries of cervical spinal nerve roots: a scanning EM study of rupture patterns in fresh tissue.

This study examines the levels at which fresh rat ventral and dorsal C4 to T1 spinal roots rupture under traction stress. Rupture rarely occurs at the CNS-PNS transitional zone. Despite its delicate appearance this is strengthened in a number of ways, so that it is less vulnerable than the roots and their constituent rootlets and aggregated rootlet bundles (ARBs). Ventral roots commonly rupture either where the rootlets join to form the ARBs, along the course of the latter, or where these in turn join to form the ventral root. Dorsal root rupture shows a similar pattern but has a higher frequency of rupture within the root proper than is the case with the ventral roots. The level of rupture also varies systematically over the series of roots examined: rupture points tend to be located at more distal levels in caudal roots. This may occur because of mechanical differences in the distribution of traction stress along roots, related to their courses through the vertebral canal. Upper roots run transversely and the traction force is transmitted directly to rootlet levels, while more caudal roots run obliquely and tend to rupture where they are drawn taut against the pedicle. Many of the morphological features of ruptured roots would tend to inhibit regeneration of fibres distally. Differences in the pattern of rupture between fresh and fixed roots are examined. The latter tend to rupture at levels closer to the CNS than the former.

Animals↗
PubMed2004

Vitrectomy in vitreomacular traction syndrome evaluated by ocular coherence tomography (OCT) retinal mapping.

PURPOSE: To evaluate vitreomacular traction syndrome with ocular coherence tomography (OCT) retinal mapping before and after vitrectomy. METHODS: A prospective study of 11 eyes with vitreomacular traction syndrome was carried out. Ocular coherence tomography retinal mapping was performed before vitrectomy and 6 months postoperatively. Visual acuity (VA) was measured with the ETDRS chart. RESULTS: All patients showed a reduction in the thickness of the macular area postoperatively. The mean thickness in the central macular area was 609 microm preoperatively and 243 microm 6 months postoperatively (p < 0.001). Ten patients had an increase in VA of at least two lines on the ETDRS chart and in one patient VA was unchanged. The mean improvement in VA was 3.1 lines. CONCLUSION: Retinal mapping with OCT is a good method of evaluating the thickness of the macula before and after surgery in vitreomacular traction syndrome and vitrectomy improves VA in most cases.

Aged↗
PubMed1997

An anisotropic biphasic theory of tissue-equivalent mechanics: the interplay among cell traction, fibrillar network deformation, fibril alignment, and cell contact guidance.

We present a general mathematical theory for the mechanical interplay in tissue-equivalents (cell-populated collagen gels): Cell traction leads to compaction of the fibrillar collagen network, which for certain conditions such as a mechanical constraint or inhomogeneous cell distribution, can result in inhomogeneous compaction and consequently fibril alignment, leading to cell contact guidance, which affects the subsequent compaction. The theory accounts for the intrinsically biphasic nature of collagen gel, which is comprised of collagen network and interstitial solution. The theory also accounts for fibril alignment due to inhomogeneous network deformation, that is, anisotropic strain, and for cell alignment in response to fibril alignment. Cell alignment results in anisotropic migration and traction, as modeled by a cell orientation tensor that is a function of a fiber orientation tensor, which is defined by the network deformation tensor. Models for a variety of tissue-equivalents are shown to predict qualitatively the alignment that arises due to inhomogeneous compaction driven by cell traction.

Anisotropy↗
PubMed2006

Viscous scattering of a pressure wave: calculation of the fluid tractions on a biomimetic acoustic velocity sensor.

In the paper we give a method for calculating the tractions (local forces) of the fluid motion determined by an incoming plane pressure wave on an artificial hair cell transducer structure. The sensing element of the transducer is a standing high aspect ratio cilium in the shape of a narrow thin curved beam (tape-like), which can be easily fabricated in micro-/nanotechnology. The method is based on considering the system of partial differential equations describing the motion of the compressible viscous fluid in an acoustic linearized approximation, and representation of the velocity field as a viscous acoustic single-layer potential. The boundary conditions, stating the cancellation of the velocity components on the solid beam, yield a two-dimensional (2-D) system of three integral equations over the beam's surface for the traction components. In the case of a narrow cilium, the system of integral equations furnishes a system of two 1-D integral equations over the symmetry curve of the structure for obtaining the tangential and normal components of the traction. This system is solved numerically by a finite (boundary) element method. The numerical code written for solving the problem was applied to some particular structures. The last structure is similar to the trichobothrium of a spider Cupiennius salei. The results obtained show that the curvature of the hair is enhancing sensitivity to flows directed normal to the main shaft of the hair confirming the assertion of Barth et al. [Philos. Trans. R. Soc. London, Ser. B 340, 445-461 (1993)].

Acoustics↗
PubMedDate not supplied

Cellular adhesiveness, contractility, and traction: stick, grip, and slip control.

Translocation of cells over solid substrata depends on generation of motive force, in crawling tissue cells, brought about by regulated contractility of intracellular actomyosin. Intracellular contractile machinery has a direct, structural connection to the cell surface. Hence, regulated adhesiveness of the cell surface provides a mechanism whereby a cell can fine tune the extent of tractional forces that are necessary for effective translocation. Cells are able to control adhesiveness of surfaces (stick), contractility (grip), and the extent of traction exerted on the substratum (slip). Here, I discuss several aspects of local (subcellular) regulation of adhesiveness and contractility and speculate on how cells, given a choice of the substratum, decide on how and where to apply traction.

Biomechanical Phenomena↗
PubMed1988

Traction osteophytes of the lumbar spine: radiographic-pathologic correlation.

Previous reports have emphasized two types of osteophytes on the anterior aspects of the lumbar vertebral bodies: the common claw osteophyte and the less common but more significant traction osteophyte, which is indicative of spinal instability. To delineate the importance of the traction osteophyte, a radiographic-pathologic study was conducted. The results indicate that claw osteophytes are more frequent than traction osteophytes, that both may coexist in a single vertebral body, and that, in most cases, these osteophytes appear to represent different stages of the same pathologic process.

Humans↗
PubMed2006

Thrombin-induced contraction in alveolar epithelial cells probed by traction microscopy.

Contractile tension of alveolar epithelial cells plays a major role in the force balance that regulates the structural integrity of the alveolar barrier. The aim of this work was to study thrombin-induced contractile forces of alveolar epithelial cells. A549 alveolar epithelial cells were challenged with thrombin, and time course of contractile forces was measured by traction microscopy. The cells exhibited basal contraction with total force magnitude 55.0 +/- 12.0 nN (mean +/- SE, n = 12). Traction forces were exerted predominantly at the cell periphery and pointed to the cell center. Thrombin (1 U/ml) induced a fast and sustained 2.5-fold increase in traction forces, which maintained peripheral and centripetal distribution. Actin fluorescent staining revealed F-actin polymerization and enhancement of peripheral actin rim. Disruption of actin cytoskeleton with cytochalasin D (5 microM, 30 min) and inhibition of myosin light chain kinase with ML-7 (10 microM, 30 min) and Rho kinase with Y-27632 (10 microM, 30 min) markedly depressed basal contractile tone and abolished thrombin-induced cell contraction. Therefore, the contractile response of alveolar epithelial cells to the inflammatory agonist thrombin was mediated by actin cytoskeleton remodeling and actomyosin activation through myosin light chain kinase and Rho kinase signaling pathways. Thrombin-induced contractile tension might further impair alveolar epithelial barrier integrity in the injured lung.

Actins↗
PubMed1995

Canalicular reconstruction for difficult cases: lacrimal stents and multiple traction sutures.

Twelve cases with canalicular disorders were treated by a new technique using multiple traction sutures (MTS) under an operating microscope. The MTS using black silk or 5-0 nylon were applied at the medial canthus, near the upper and lower puncta and at the caruncle. Additional traction sutures were applied to locate a deep canalicular system if needed, resulting in a total of 5-10 traction sutures. The patient's face was turned sideways towards the left in the operation of the right eye, and to the right in the operation of the left eye. By using the new technique, the opening of the common canaliculus could easily be located without resorting to an open-sky technique requiring skin incision. A new canaliculus could easily be made using a free graft of oral mucous membrane between the common canaliculus and medial canthus with the help of MTS in 7 cases out of 12. As stents, a match-style silicone tubing, a nunachaku-style silicone tubing, an ordinary silicone tubing and a silicone tubing with a silicone sponge were used for 7, 1, 1 and 3 cases, respectively. After a mean follow-up 17.2 months, symptomatic relief and patency of the lacrimal passage were achieved in all cases.

Adult↗
PubMed1981

Mechanisms in traction retinal detachment.

We have developed a reproducible model of traction retinal detachment in the rhesus monkey secondary to a penetrating eye injury. The model is characterized histologically by intravitreal fibroblastic proliferation and by epiretinal and by retroretinal membranes. Cells proliferating within the vitreous and in the epiretinal membranes have the ultrastructural characteristics of myofibroblasts. The presence of these contractile cells suggests that vitreous traction and the contraction of epiretinal membranes may be cell mediated. Our findings suggest that the pathophysiology of traction retinal detachment has many features in common with the normal process of wound healing and in particular with the mechanisms responsible for wound contraction and cicatrization.

Animals↗
PubMedDate not supplied

Experimental tractional retinal detachment: an immunohistochemical study.

PURPOSE: This study investigated the pathogenesis of tractional retinal detachment associated with proliferative vitreoretinopathy in an experimental model, using immunohistochemical staining. METHODS: To produce tractional retinal detachment in rabbit eyes, homologous cultured fibroblasts obtained from the gluteal muscle fascia were injected intravitreously. Right eyes of 20 rabbits in the study group, and 7 rabbits in the control group were followed for 26 days at weekly intervals with indirect ophthalmoscopy and fundus photographs. RESULTS: During the follow-up period grade III tractional retinal detachment developed in 11 eyes, grade II in six, and grade 1 in three eyes. The spindle-shaped cells contributed predominantly to the development of epiretinal membrane, and a smaller number of round small and large cells. In 10/17 grade II and III eyes, spindle-shaped cells had vimentin, 7/10 had actin, 5/17 had GFAP, 4/17 had S-100 protein immunoreactivity. Round small and large cells expressed S-100 protein, GFAP and actin in 5/17 eyes. Epiretinal membrane appeared to be formed by spindle-shaped fibroblast-like cells and small and large round glia-like cells. Actin positivity of spindle-shaped and round cells was taken as a marker of contractile elements of the cells and their locomotional features. CONCLUSIONS: These features are believed to be involved in contraction of the membrane and retinal detachment.

Actins↗
PubMedDate not supplied

Circulatory responses and halothane concentrations during gastric or gallbladder traction with and without neuromuscular blockade.

Systolic and diastolic blood pressures and heart rates did not change significantly and ventricular dysrhythmias did not occur during gastric or gallbladder traction in patients anesthetized with N2O-halothane, with or without d-tubocurarine or pancuronium neuromuscular blockade. Systolic and diastolic blood pressures and heart rates just before abdominal viscera traction were less (p is less than 0.05) in patients paralyzed with d-tubocurarine than with pancuronium despite similar arterial halothane concentrations. In contrast, these measurements in patients without neuromuscular blockade were similar to those during pancuronium paralysis despite significantly greater arterial halothane concentrations in the unparalyzed patients. The authors conclude that circulatory responses during gastric or gallbladder traction are clinically insignificant during N2O-halothane administration, with or without d-tubocurarine or pancuronium neuromuscular blockade. Intraoperative blood pressures and heart rates were influenced by the neuromuscular blocker chosen. Neuromuscular blockade permitted anesthetic maintenance with lower arterial halothane concentrations than when paralysis was not present.

Abdomen↗
PubMed1976

Experimental cleavage of chorioretinal scars by traction and subretinal fluid.

The resistance to separation by localized traction and exudative retinal detachment of experimental chorioretinal scars produced with argon laser photocoagulation, cryothermy and diathermy was tested in rabbits. In vivo, the area of retinal separation over the scar was similar to that obtained by traction on normal retina. Moreover, the retinal cleavage occurred at the level of the scar regardless of the scar inducing modality, indicating that the scar is the weakest point in the retina-pigment epithelium joint. However, spaced and dense chorioretinal scars produced by argon laser photocoagulation, diathermy and cryothermy usually remained attached after experimental production of exudative retinal detachments with penicillin G intravitreal injections. This study indicates that the resistance to detachment of the normal retina by traction may be as strong as that of the scarred tissue and that the chorioretinal scars' effect is related to lesser fluid penetration into the treated area.

Animals↗
PubMed2000

[Scanning laser ophthalmoscopic microperimetry on idiopathic epiretinal membrane and vitreomacular traction syndrome].

PURPOSE: To evaluate visual function before and after vitrectomy for idiopathic epiretinal membrane and vitreomacular traction syndrome. METHODS: Microperimetry with scanning laser ophthalmoscope (SLO) was performed in 4 eyes with idiopathic epiretinal membrane (IERM) and 2 eyes with vitreomacular traction syndrome (VMTS), before and at least 3 months after vitrectomy. RESULTS: Five eyes had preoperative scotoma, which disappeared postoperatively. In 1 eye, absolute and relative scotomas developed postoperatively over the areas where the retinal surface was vigorously scratched to peel off an overlying membrane, and in another eye new scotomas appeared over a newly formed epiretinal membrane 8 months after vitrectomy. CONCLUSIONS: To our knowledge, the present report is the first to describe preoperative absolute scotoma in IERM, VMTS and also iatrogenic absolute scotoma due to retinal scratching. SLO microperimetry is useful for evaluation of visual function before and after vitrectomy for epiretinal membrane and vitreomacular traction syndrome.

Aged↗
PubMed2001

[Idiopathic vitreomacular traction syndrome. Vitrectomy results].

PURPOSE: Evaluate the visual results, the complications and the prognosis factors of surgery for idiopathic vitreomacular traction syndrome. METHODS: We retrospectly reviewed 29 consecutive eyes that had undergone pars plana vitrectomy and posterior epiretinal membrane peeling for idiopathic vitreomacular traction syndrome. RESULTS: The mean follow-up after surgery was 17.7 months. Among the 29 cases, 21 were phakic. Visual acuity improved by 2 lignes or more in 72.4% of the cases and the mean improvement was 2.7. Eyes with preoperative visual acuity of 0.25 or more had better postoperative vision than the others (0.42vs0.65;p=0.006). During the follow-up, 10 patients underwent phacoemulsification and posterior chamber implantation (47.6%). The mean visual acuity of these 10 cases was poorer than the mean visual acuity of the 8 pseudophakic patients that underwent vitrectomy (0.45vs0.61;p=0.046). Five recurrences of epiretinal membrane were observed (17.2%). CONCLUSIONS: Surgical treatment of vitreomacular traction syndrome improves visual acuity in most of cases. Further studies with optical coherence tomography are necessary to understand the pathogenic mechanisms of vitreomacular interface syndromes.

Aged↗
PubMed2001

[Pars plana vitrectomy in treatment of tractional edema of the macula].

We analysed the causes and the consequences of traction macular edema with the possibility of solution of this stage by pars plana vitrectomy with removal of vitreomacular traction and epiretinal macular membranes. An analysis of preoperative and postoperative findings of 4 patients was made. There were found idiopathic epiretinal membranes in 3 cases and vitreomacular traction syndrome in 1 case. We reported postoperative improvement of visual acuity in 3 cases, stabilisation of postoperative state was reached in 1 patient.

Adult↗
PubMed2002

[Instant repair of soft tissue defect of limb by simple skin traction technique].

OBJECTIVE: To summarize the application of simple skin traction technique in repair of soft tissue defect of limb. METHODS: From 1999, 42 cases of soft tissue defect of limbs were repaired by simple skin traction technique instantly; the defect area ranged from 2.5 cm x 2.0 cm to 8.0 cm x 6.5 cm. RESULTS: The soft tissue defect less than 8.0 cm can be sutured instantly. All of the wound achieved primary healing without infection and necrosis of skin edge, the circulation and sensation of limbs were normal; healing time was 10 days to 16 days, 12.8 days on average. Thirty-two cases were followed up for 6 months; the shape and function recovered well. CONCLUSION: Simple skin traction technique is a good option to repair the soft tissue defect of limbs.

Adolescent↗