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At least 685 records · Page 38Linked to original sources
PubMed1999

Follow-up of functionally lost eyes after vitrectomy and silicone oil tamponade for tractional retinal detachment.

BACKGROUND: Is there any association between, on the one hand, retention or removal of silicone oil or any specific ocular finding in patients with functionally lost eyes after vitrectomy and silicone oil tamponade for tractional retinal detachment and, on the other, a greater chance of preservation of the eye? This information is important in deciding whether to remove silicone oil, as well as in counseling patients about their individual chances of preserving their eye. METHODS: Seventy-three consecutive patients with a functionally lost eye with a minimum follow-up of 3 years were retrospectively studied. The relation between the variables at study entry or the removal of silicone oil during the follow-up period and a subsequent intervention (enucleation, evisceration or conjunctival cover with a scleral shell) were tested for statistical significance with Cox proportional hazards analysis. RESULTS: The absence or removal of silicone oil was not associated with a greater chance of finally preserving the eye. Nor could we identify other factors which predicted better chances of preservation. CONCLUSION: The notion that functionally lost eyes after treatment with vitrectomy and silicone oil tamponade for complicated tractional retinal detachment have better chances of preservation of the eye without silicone oil is not supported by our study.

Blindness↗
PubMed2003

Laparoscopic resection of an abdominal wall desmoid using a modified suture traction technique: the "marionette trick".

Desmoids are rare mesenchimal tumors that may originate also inside the abdomen or in the abdominal wall. These tumors are biologically characterized by a tendency to local growth, and only rarely are they able to develop distant metastases. Surgical excision usually is the best treatment with a chance of a cure. In the few reports on intraabdominal or abdominal wall desmoids, open surgery always was performed. The first case of successful laparoscopic resection of a symptomatic anterior wall desmoid tumor with intraabdominal growth is reported. During the procedure, it was difficult to mobilize and grasp the mass using the common laparoscopic instruments, but with the help of the "marionette trick," modified suture traction technique, the tumor could be removed easily using only three trocars. With four traction sutures minimizing the wall trauma, the trick made it possible to mobilize the mass in at least, seven directions, according to the principles of physical forces and vectors. This simple trick can be helpful for other common laparoscopic procedures, avoiding the insertion of sometimes ineffective instruments through more traumatic trocars.

Abdominal Neoplasms↗
PubMed2007

Cell traction force and measurement methods.

Cell traction forces (CTFs) are crucial to many biological processes such as inflammation, wound healing, angiogenesis, and metastasis. CTFs are generated by actomyosin interactions and actin polymerization and regulated by intracellular proteins such as alpha-smooth muscle actin (alpha-SMA) and soluble factors such as transforming growth factor-beta (TGF-beta). Once transmitted to the extracellular matrix (ECM) through stress fibers via focal adhesions, which are assemblies of ECM proteins, transmembrane receptors, and cytoplasmic structural and signaling proteins (e.g., integrins), CTFs direct many cellular functions, including cell migration, ECM organization, and mechanical signal generation. Various methods have been developed over the years to measure CTFs of both populations of cells and of single cells. At present, cell traction force microscopy (CTFM) is among the most efficient and reliable method for determining CTF field of an entire cell spreading on a two-dimensional (2D) substrate surface. There are currently three CTFM methods, each of which is unique in both how displacement field is extracted from images and how CTFs are subsequently estimated. A detailed review and comparison of these methods are presented. Future research should improve CTFM methods such that they can automatically track dynamic CTFs, thereby providing new insights into cell motility in response to altered biological conditions. In addition, research effort should be devoted to developing novel experimental and theoretical methods for determining CTFs in three-dimensional (3D) matrix, which better reflects physiological conditions than 2D substrate used in current CTFM methods.

Algorithms↗
PubMed1984

The importance of fluid absorption, traction, intraocular currents, and chorioretinal scars in the therapy of rhegmatogenous retinal detachments. XLI Edward Jackson memorial lecture.

The combination of traction on the retina and of intraocular currents in the presence of a retinal hole is the cause of rhegmatogenous retinal detachment. The strong suction forces of the pigment epithelium and choroid counteract such a development. Chorioretinal scars serve as a seal against currents. Eliminating the effects of traction and of intraocular currents and making use of the absorption forces of the pigment epithelium and choroid are the primary aims in successfully treating rhegmatogenous retinal detachment. Direct closure of the retinal hole is not always necessary.

Adult↗
PubMed1975

Early or late cervical traction therapy of Class II malocclusion in the mixed dentition.

It was the purpose of this investigation to evaluate the effect of cervical traction in Class II malocclusions in which treatment was started either early or late in the mixed dentition. Evaluation of the data indicated that the amount and direction of growth were of the greatest importance for effective treatment. Vertical growth appeared to be of particular importance and correlated to the anteroposterior improvement of the relationship between the maxilla and the mandible. Cervical traction, as advocated in this study, was more favorable in the early mixed dentition. A greater amount of growth and a subsequent increased reduction in the ANB angle was recorded during this period. The effect of treatment upon the maxilla, as revealed in posterior movement of the maxillary molar and the pterygomaxillary fissure, was more evident in early treatment. Great individual variability was observed, but in cases in which there was a severe discrepancy in the relationship between the maxilla and the mandible treatment in the early mixed dentition may be essential.

Cephalometry↗
PubMed1988

Retinal hemorrhages and traction forces in vacuum extraction.

The relationship between the traction forces used in 53 clinically indicated vacuum extractions and the incidence and degree of retinal hemorrhages observed in the neonates within 24 hours after birth was examined. A Vacuum Extractor Recorder (Type SF 30, Knick), was used to measure the traction force necessary for delivery of the fetal head. No relationship could be demonstrated between the force time integral and the appearance and grading of retinal bleedings.

Adult↗
PubMed2006

Tractional internal limiting membrane detachment in highly myopic eyes.

PURPOSE: To report the clinical features of tractional internal limiting membrane (ILM) detachment in highly myopic eyes with posterior staphyloma. DESIGN: Observational case report. METHODS: We reviewed the optical coherence tomography images of 249 eyes in the high myopia clinic. ILM detachment was observed in six eyes (2.4%). We investigated the clinical feature of this finding. RESULTS: Myopic foveoschisis (MF) was present in four of the six eyes (67%) (six patients, two men and four women; mean age, 57.3 years). The mean axial length was 29.3 mm and the mean refractive error was -15.0 diopters. The best-corrected visual acuity levels ranged from 20/400 to 20/13. CONCLUSIONS: Rigidity of the ILM seems to cause tangential traction and results in a major cause of a disease specific to high myopia; that is, MF.

Aged↗
PubMed2004

Systematic traction techniques in minimal-access pediatric cardiac surgery.

Minimal-access pediatric cardiac surgery is now common in the treatment of simple congenital heart defects. However, methods of securing a good, unobstructed view for surgery and the difficulties of working in a deep, narrow field jeopardize safety in surgical procedures, especially for less experienced surgeons have been described. Our systematic, step-by-step traction techniques on the skin, the pericardium, the right atrial appendage, the aortic root, both venae cavae, and the free wall of the right ventricular outflow, using a mechanical retractor and traction sutures, facilitate surgical field exposure and the achievement of safety. As described below, our procedures are simple, allow direct inspection, and assist those working toward technical mastery.

Adolescent↗
PubMed2004

Critical conditions for pattern formation and in vitro tubulogenesis driven by cellular traction fields.

In vitro angiogenesis assays have shown that tubulogenesis of endothelial cells within biogels, like collagen or fibrin gels, only appears for a critical range of experimental parameter values. These experiments have enabled us to develop and validate a theoretical model in which mechanical interactions of endothelial cells with extracellular matrix influence both active cell migration--haptotaxis--and cellular traction forces. Depending on the number of cells, cell motility and biogel rheological properties, various 2D endothelial patterns can be generated, from non-connected stripe patterns to fully connected networks, which mimic the spatial organization of capillary structures. The model quantitatively and qualitatively reproduces the range of critical values of cell densities and fibrin concentrations for which these cell networks are experimentally observed. We illustrate how cell motility is associated to the self-enhancement of the local traction fields exerted within the biogel in order to produce a pre-patterning of this matrix and subsequent formation of tubular structures, above critical thresholds corresponding to bifurcation points of the mathematical model. The dynamics of this morphogenetic process is discussed in the light of videomicroscopy time lapse sequences of endothelial cells (EAhy926 line) in fibrin gels. Our modeling approach also explains how the progressive appearance and morphology of the cellular networks are modified by gradients of extracellular matrix thickness.

Biomechanical Phenomena↗
PubMed2003

Traction suture of the cervix: a novel procedure with loop electrosurgical excision.

BACKGROUND: Loop electosurgical excision procedure (LEEP) of the transformation zone has become the preferred treatment of cervical intraepithelial neoplasia (CIN). CASE: An inadvertent vesicovaginal laceration occurred during LEEP of CIN2 in a 57-year-old-woman with a cystocele. We developed a traction suture of the cervix that we used during LEEP that permits manipulation of the cervix outward, away from the nearby protruding tissues. CONCLUSION: Traction suture during LEEP may reduce inadvertent lacerations in patients with cystocele, rectocele, and other protruding tissues.

Electrosurgery↗
PubMed2001

Vitreoretinal traction maculopathy caused by retinal diseases.

PURPOSE: To study the morphological findings of vitreoretinal traction maculopathy caused by retinal vascular diseases and their changes after vitrectomy. METHODS: Optical coherence tomographic images of 13 eyes of 12 cases were evaluated before and after vitrectomy. RESULTS: The tractional force appeared to be mainly tangential with a possible anterior vector in 11 eyes, and mainly in the anterior direction in 2 eyes. After surgery, the increased foveal thickness decreased markedly in all eyes, and visual acuity improved in 8 eyes. CONCLUSION: Preoperative optical coherence tomographic examination can reveal the fine structure of vitreoretinal separations and adherences caused by retinal vascular diseases. These observations permitted better surgical planning and results.

Adult↗
PubMed1989

Surgical management of retinal traction caused by toxocariasis.

We reviewed the results of vitreous surgery in 12 eyes of 12 patients with tractional macular detachment from Toxocara canis. We performed a vitrectomy and membrane peeling in all eyes, with additional scleral buckling in four eyes. After a minimum of six months' follow-up, ten of the 12 eyes (83%) had complete retinal reattachment. Visual acuity improved in seven eyes, two had no change, and three eyes had decreased visual acuity. Good postoperative vision correlated best with good preoperative vision. Preoperative traction retinal folds through the macula were associated with a poor visual outcome.

Adolescent↗
PubMed1996

Imaging the traction stresses exerted by locomoting cells with the elastic substratum method.

The cytoskeletal activity of motile or adherent cells is frequently seen to induce detectable displacements of sufficiently compliant substrata. The physics of this phenomenon is discussed in terms of the classical theory of small-strain, plane-stress elasticity. The main results of such analysis is a transform expressing the displacement field of the elastic substrate as an integral over the traction field. The existence of this transform is used to derive a Bayesian method for converting noisy measurements of substratum displacement into "images" of the actual traction forces exerted by adherent or locomoting cells. Finally, the Monte Carlo validation of the statistical method is discussed, some new rheological studies of films are presented, and a practical application is given.

Animals↗
PubMed2004

Percutaneous traction-assisted EMR by using an insulation-tipped electrosurgical knife for early stage gastric cancer.

BACKGROUND: EMR now is accepted as a minimally invasive treatment for early stage gastric cancer. However, the endoscopic approach sometimes is limited by the size and location of the tumor. The technique and early results of percutaneous, traction-assisted EMR for resection of larger early stage gastric cancers is described. METHODS: EMR, by using an insulation-tipped electrosurgical knife, was performed with the simultaneous assistance of laparoscopy devices. A small snare was introduced into the gastric lumen through a gastric port (2-mm diameter) to grasp and pull the EGC away from the muscularis propria to facilitate resection. RESULTS: The technique was performed successfully in our endoscopic suite in the first patient under general anesthesia and the remaining seven under conscious sedation. Tumors situated in any part of the stomach could be reached with percutaneous assistance, and this facilitated en bloc resection of large specimens (mean size 50 mm). The procedure was performed in about 60 minutes. Seven patients (88%) resumed eating 1 or 2 days after surgery. All patients were discharged after 1 week without complication. CONCLUSIONS: Percutaneous, traction-assisted EMR is useful for resection of large lesions en bloc and can be performed easily and safely under direct vision.

Adult↗
PubMed2004

Traction injury during minimally invasive harvesting of the saphenous vein is associated with impaired endothelial function.

OBJECTIVE: Many methods of minimally invasive surgical harvesting of the great saphenous vein have been developed because of the morbidity related to the long skin incision after traditional (open) great saphenous vein harvesting. One such method involves the use of multiple small incisions separated by 10- to 15-cm skin bridges through which the saphenous vein is harvested. We hypothesized that this method of saphenous vein harvesting might subject the saphenous vein to considerable traction forces, resulting in impaired endothelial cell function. METHODS: Four-millimeter great saphenous vein segments were obtained from patients undergoing elective coronary artery bypass graft surgery. Group A (minimally invasive surgery) consisted of 23 rings from 20 patients (age, 65.8 +/- 11.1 years, mean +/- SD). Group B (open harvesting) consisted of 33 rings from 8 patients (age, 69.8 +/- 8.6 years). All great saphenous vein segments were undistended and were used within 24 hours of harvesting. Isometric tension experiments were performed on each ring of the great saphenous vein by using a force-displacement transducer to measure the force of contraction in grams. Measurements included developed force after exposure to high-potassium depolarizing solution and 50 micromol/L phenylephrine and decrease in force of contraction (relaxation) after exposure to 1 and 10 micromol/L acetylcholine. RESULTS: There were no differences between the minimally invasive surgery and open harvesting groups in their responses to high-potassium depolarizing solution or phenylephrine: high-potassium depolarizing solution, contractions of 4.26 +/- 0.72 g (mean +/- SEM) and 3.95 +/- 0.38 g, respectively (P =.70); phenylephrine, contractions of 3.49 +/- 0.63 g and 2.73 +/- 0.39 g, respectively (P =.41). There was no net relaxation in segments from the minimally invasive surgery group after exposure to 1.0 or 10 micromol/L acetylcholine. In contrast, rings from the open harvesting group demonstrated relaxation of -0.41 +/- 0.07 g and -0.32 +/- 0.09 g after exposure to 1.0 and 10 micromol/L acetylcholine, respectively. CONCLUSIONS: In undistended saphenous vein segments isolated from patients undergoing minimally invasive surgical and open techniques of harvesting, there was no acetylcholine-mediated endothelium-dependent relaxation in the minimally invasive surgery group. Therefore harvesting of the great saphenous vein through multiple small incisions might result in endothelial dysfunction, possibly caused by traction injury.

Aged↗
PubMed1980

Closed vitrectomy in the management of diabetic traction retinal detachment.

One hundred and seventy-four instances of diabetic traction retinal detachment in which the patient underwent closed vitrectomy during the period of January 1970 to December 1978 and had adequate follow-up ranging from six months to five years are reported. As a rule, eyes with vision better than 20/200, or with inaccurate light projection, or with no response to electrophysiologic tests were excluded. The surgical technique avoided stripping of vitreous membranes. Closed vitrectomy was combined with scleral buckling in eyes with retinal breaks, and with scleral resection in eyes with incomplete section of traction membranes. Anatomic improvement was noted in 75.3% of the eyes; vision improved in 64.9% of the eyes; new or recurrent vitreous hemorrhage was observed in 43.1%; corneal decompensation in 51.8%, rubeosis iridis in 23.0%, phthisis bulbi in 9.2%, iatrogenic retinal break in 8.6%, postoperative rhegmatogenous retinal detachment in 5.2%, and iatrogenic cataract in 4.6%.

Adolescent↗
PubMed1980

Diabetic traction retinal detachment. Factors influencing final visual acuity.

A group of eyes with clear media and diabetic traction retinal detachments treated with vitreous surgery were statistically analyzed to identify those parameters that would allow us to improve case selection. The configuration of the retinal detachment proved to be important, with hammock and flat diffuse central detachments having a good prognosis, and highly elevated, atrophic detachments such as table-top and tent-shaped demonstrating a poor prognosis. Eyes with florid diabetic retinopathy did less well than those with more inactive forms of retinopathy. Preretinal membranectomy, although accompanied by an increased rate of iatrogenic retinal tears, has a definite role in the treatment of more complex traction detachments and increases the number of eyes that may benefit from surgery. Eyes with preoperative vision better than 5/200 did significantly better than eyes with poorer preoperative vision.

Adolescent↗
PubMed1987

Proliferative vitreoretinopathy. The mechanism of development of vitreoretinal traction.

Proliferative vitreoretinopathy (PVR) is the leading cause of failure of retinal detachment surgery. In this disorder, contractile cellular membranes form within the vitreous cavity. Retinal pigment epithelial (RPE) cells are an early and important component of these membranes. Contraction is mediated by cellular events and this contraction results in the formation of traction retinal detachments. Using the techniques of time-lapse cinemicrography, the authors studied the interaction of single RPE cells with individual strands of collagen. RPE cells pull the collagen fibers toward them using alternating extension and retraction of their lamellipodia. (The mechanism can be likened to sailors pulling in sheets of a sal in a hand-over-hand manner.) The collagen is not engulfed by the cell, but instead is piled up in a small bundle adjacent to the cell. Using this mechanism, each cell can reel in several times its length of collagen in 1 hour. In this manner, a small number of RPE cells may be able to collapse the vitreous gel and exert tractional forces.

Adult↗