SEARCH · PubMed Health

Results for “STRING”

Explore indexed PubMed citations for clinical trials, systematic reviews and public health research. Read source abstracts and follow each citation to its original PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 145 records · Page 8Linked to original sources

PubMedDate not supplied

IUDs and PID: a comparative trial of strings versus stringless devices.

An international multicentered clinical trial was designed to determine the possible role of intrauterine device (IUD) marker strings in the etiology of pelvic inflammatory disease (PID). A total of 1265 women were admitted and randomly allocated to receive either a standard TCu200 IUD or a TCu200 IUD without marker strings. These patients were followed-up through 12 months postinsertion. No statistically significant differences were found between the two groups of IUD users with respect to the incidence of PID or other types of infection or inflammation. The 12-month life table termination rates and overall continuation rates were also similar for users of the respective devices, with the exception of removal rates for bleeding/pain, which were significantly higher in the strings group than in the stringless group. However, the number of bleeding/pain complaints ever reported during the study were not statistically different in the two study groups. The study results indicate that the IUD string does not play an important role in the etiology of PID associated with the use of IUDs.

Adult↗

PubMed2007

Special anoscope for easy purse-string suture application in stapled hemorrhoidopexy.

BACKGROUND: Internal hemorrhoids and loose rectal mucosa may block exposure during the purse-string suturing in stapled hemorrhoidopexy, and this may lead to complications. MATERIALS AND METHODS: To retract the prolapsing rectal mucosa, we modified the purse-string anoscope of the PPH01 kit (Ethicon-Endosurgery, Cincinnati, OH, USA) and produced a special anoscope. The open part of the purse-string suture anoscope is covered by transparent acrylic (Orthoacryl, Dentaurum, Pforzheim, Germany). The covering had completely cylindrical outer and inner surfaces and was thin enough to let the anoscope easily rotate in the anal dilator and to let the 26 mm curved, round-bodied needle of the 2/0 polypropylene suture move in the anoscope. A window, 3 cm long and 3-4 mm wide, was opened at the angled part of the anoscope 2 cm to the tip. This special anoscope was used for the purse-string suture during the stapled hemorrhoidopexy procedure in five patients. RESULTS AND CONCLUSIONS: No postoperative complications, early or late, were encountered, and we propose that stapled hemorrhoidopexy procedure can be applied more easily by using this special anoscope.

Equipment Design↗

PubMed1976

Retrograde esophageal dilatation in children: an alternative to the indwelling string.

Repeated esophageal dilatation for chronic strictures secondary to corrosive burns or anastomotic scarring is commonly performed by the retrograde technic in children. This requires the presence of an indwelling string, tied in a circle, entering the nose, and exiting the gastrostomy site. Long-term presence of this string frequently leads to nasal and gastrostomy excoriations and resultant patient discomfort. We advocate and describe a technic using a piece of Silastic tubing as an alternative to the indwelling string. This has met with increased patient acceptance and comfort as compared with the previous "heavysilk" or other "string" materials.

Burns, Chemical↗

PubMed1985

Evoked potential correlates of intelligence: some problems with Hendrickson's string measure of evoked potential complexity and error theory of intelligence.

The string measure of evoked potential (EP) complexity is based on a new error theory of intelligence, which differs from the older speed-based formulations which focus on EP latency rather than complexity. In this note we first raise a methodological problem of arbitrariness with respect to one version of the string measure. We then provide a comparative empirical assessment of EP-IQ correlations with respect to a revised string measure (which does not suffer from the methodological problem), a latency measure, and another measure of EP complexity: average voltage. This assessment indicates that the string measure, in particular, yields quite disorderly results, and that, in general, the results favor the speed over the error formulation.

Evoked Potentials↗

PubMed1995

Degradation of maternal string mRNA is controlled by proteins encoded on maternally contributed transcripts.

In Drosophila, maternal string mRNAs are stable for the first few hours of development, but undergo specific timed degradation at the cellularisation stage. To determine whether the proteins that control this degradation are maternally or zygotically transcribed, we have used in situ hybridisation to determine the fate of maternal string transcripts in mutant embryos which lack individual chromosome arms. Our data indicate that maternal string mRNA persists for the normal period in all these mutants. Using alpha-amanitin to inhibit zygotic transcription we have shown that degradation of maternal mRNA is unaffected. Therefore, the proteins required to activate the degradation of string mRNA are encoded on a maternally contributed mRNA. We discuss possible models to explain the degradation pathway.

Amanitins↗

PubMed1993

The internal mammary artery 'string phenomenon'. Analysis of 10 cases.

The internal mammary artery (IMA) string sign has been described as a narrowing of IMA grafts in the late course after coronary artery bypass grafting. It has been assumed that this phenomenon was due to competitive flow in grafts connected to only mildly stenosed coronary arteries. We analyzed 10 cases of IMA string sign operated on between March 1988 and June 1991. Bilateral IMA was used in six cases and unilateral IMA in four. The mean interval between operation and reangiography was 14 +/- 11 months. String sign of the whole length of the IMA was detected in nine cases, and of the distal part between two sequential anastomoses in one. In all cases, the stenosis of the vessel bypassed with the narrowed graft proved to be only mild (50% or less) at reangiography. In all six cases with bilateral IMA grafts, the contralateral IMA was widely patent. These were all connected to highly stenosed or occluded coronary arteries. With respect to this observation, there is a high index of suspicion that the string phenomenon occurs due to competitive flow in only mildly stenosed coronary arteries. We decided, for our strategy in coronary artery surgery, still to aim at complete revascularization using IMAs as much as possible, but to avoid connecting IMA grafts to only mildly or moderately stenosed coronary arteries.

Coronary Angiography↗

PubMed2005

Feasibility and safety of string, wireless capsule endoscopy in the diagnosis of Barrett's esophagus.

BACKGROUND: Capsule endoscopy is a major technological advancement in the visualization of the small bowell. Its utility in the evaluation of the esophagus is mainly limited by its rapid and unpredictable transmission, thus limiting the number of pictures of the esophagus, in particular, the distal esophagus. METHODS: Strings were attached to the wireless capsule endoscopy device to allow its controlled movement up and down the esophagus. Microbiologic cultures of the capsule's surface after high-level disinfection were carried out after the procedure. At the time of recording, discomfort associated with the procedure was documented. Patient preference compared with conventional EGD was recorded. An independent endoscopist blinded to the EGD diagnoses assessed the diagnostic accuracy of pictures obtained. OBSERVATIONS: Fifty patients with Barrett's esophagus were enrolled: 28 with short-segment Barrett's and 22 with long-segment Barrett's. The procedure was safe (no strings were disrupted, and no capsule was lost), and it rendered negative microbiologic cultures after high-level disinfection. The mean recording time was 7.9 minutes; all patients with both short- and long-segment Barrett's esophagus were successfully identified. The difficulty/discomfort associated with swallowing the device, throat discomfort, gagging, moving the capsule (up and down and upon retrieval of the capsule) was none or minimal in 74%, 98%, 96%, 94%, and 76%, respectively. A single capsule was used in 24 studies, and the majority of patients (92%) preferred string-capsule endoscopy to EGD. CONCLUSIONS: String-capsule endoscopy was feasible, safe, and highly acceptable, and was preferred by patients and may prove to be more cost effective than screening EGD.

Adult↗

PubMed1979

Identification of gallbladder typhoid carriers by a string device.

The efficiency of a gelatin capsule containing a nylon string for collection of duodenal specimens was investigated in carriers of Salmonella typhosa (typhi). Cultures of duodenal specimens obtained by means of the string capsule were compared with cultures of duodenal specimens obtained by a conventional duodenal tube and with stool cultures Duodenal contents obtained with either the string or tube were more often positive for S. typhosa than were stool cultures. The string, which is as efficient as tube collection but simpler and more comfortable, may be useful in identifying carriers of S. typhosa.

Adult↗

PubMed2003

Strings of vesicles: flow behavior in an unusual type of aqueous gel.

This is a study of 10 asymmetric gemini surfactants that self-assemble into vesicles which, in turn, self-assemble into gels. The geminis have the following general structure: long-chain/phosphate/2-carbon spacer/quaternary nitrogen/short-chain. Dynamic light scattering and transmission electron microscopy (TEM) demonstrate that in dilute aqueous systems these compounds self-assemble into vesicles. The vesicles are cohesive as proven by cryo-high resolution electron microscopy (cryo-HRSEM) images that reveal a "pearls on a string" morphology. These strings of vesicles create a complex network that rigidifies the water. The one gemini in the study that does not form a gel is also the only vesicle system that, according to cryo-HRSEM and TEM, assembles into clumps rather than chains. It is proposed that the vesicles are cohesive owing to protrusion of short chains from the vesicle surfaces, thereby creating hydrophobic "patches" whose intervesicular overlap supersedes the normal membrane/membrane repulsive forces. Analogous geminis having two long chains, neither of which are thought capable of departing from their bilayers, also form vesicles, but they are noncohesive (as expected from the model). Rheological experiments carried out on the gels show that gelation is mechanically reversible. Thus, if an applied torque breaks a string, the string can rapidly mend itself as long as the temperature exceeds its calorimetrically determined T(m) value. Gel strength, as manifested by the yield stress of the soft material, was shown to be particularly sensitive to the structure of the gemini. All three individual components of the systems (geminis, vesicles, and gels) have widespread practical applications.

Delayed-Action Preparations↗

PubMed2005

String defects connecting pairs of half-integer disclinations and tilting transition of a langmuir monolayer.

The static and dynamic string defect textures connecting pairs of half-integer disclinations have been observed by Brewster angle microscopy in the solid phase of pentacosadiynoic acid Langmuir monolayers. The static string defect structures have appeared coexisting with two kinds of point disclinations that have four and two black brushes. The use of local laser heating has allowed one to observe kinetics of creation and annihilation of string defects connecting the two-half-integer disclinations in the splitting process of an s = 1 point disclination into fractional disclinations. These kinetics have been analyzed by studying the competition between the orientational elasticity of the molecules and the line tension of the string and the drag force of the disclinations.

Journal Article↗

PubMed2006

A cooperative beads-on-a-string approach to exceptionally stable DNA triplexes.

A poly(dT) oligomer can serve as the string on which synthetic hairpins possessing poly(dA) and poly(dT) arms connected by a hydrophobic perylene diimide linker are assembled like beads on a string. The synthetic hairpins form head-to-head dimers and trimers, respectively, in the absence of the poly(dT) string and in the presence of a string with inverted polarity at mid-strand. However, they assemble in cooperative head-to-tail fashion on normal poly(dT) oligomers.

Circular Dichroism↗

PubMed1999

Modified purse-string closure for reconstruction of moderate/large surgical defects of the face.

BACKGROUND: Large surgical defects of the face can often be difficult to repair. Extensive adjacent tissue transfer may be necessary and may result in significant scars and possible flap compromise. Often there may be less donor tissue available than is necessary to achieve closure. The alternative is a split-thickness skin graft, which often has a poor cosmetic outcome with poor color match and contour irregularities. OBJECTIVE. A novel approach to closing large surgical defects of the face is described. This relies on a combination of side-to-side bilateral advancement and circumferential tissue recruitment utilizing the purse-string suture. METHODS: Report of illustrated cases. RESULTS: A 3.5 x 5.5 cm preauricular cheek defect, which could not be closed primarily side-to-side, was successfully completely closed in a curvilinear fashion by implementing both side-to-side bilateral advancement and circumferential tissue recruitment. A 3.8 x 5.5 cm cheek defect and a 6.0 x 8.0 cm temple defect were significantly decreased by using the modified purse-string closure. Healing by second intention in these two cases provided an excellent cosmetic result. CONCLUSION: The use of the purse-string closure utilizing circumferential tissue recruitment in combination with side-to-side bilateral adjacent tissue transfer allows seemingly large facial defects to be closed or significantly reduced in size. Such closure is evident even in cases where poor skin laxity and size of the defect would not appear to allow this. The modified purse string closure can result in an excellent cosmetic outcome.

Aged↗

PubMed2005

Distinct temporal-spatial roles for rho kinase and myosin light chain kinase in epithelial purse-string wound closure.

BACKGROUND & AIMS: Small epithelial wounds heal by purse-string contraction of an actomyosin ring that is regulated by myosin light chain (MLC) kinase (MLCK) and rho kinase (ROCK). These studies aimed to define the roles of these kinases in purse-string wound closure. METHODS: Oligocellular and single-cell wounds were created in intestinal epithelial monolayers. Fluorescence imaging and electrophysiologic data were collected during wound closure. Human biopsies were studied immunohistochemically. RESULTS: Live-cell imaging of enhanced green fluorescent protein-beta-actin defined rapid actin ring assembly within 2 minutes after wounding. This progressed to a circumferential ring within 8 minutes that subsequently contracted and closed the wound. We therefore divided this process into 2 phases: ring assembly and wound contraction. Activated rho and ROCK localized to the wound edge during ring assembly. Consistent with a primary role in the assembly phase, ROCK inhibition prevented actin ring assembly and wound closure. ROCK inhibition after ring assembly was complete had no effect. Recruitment and activation of MLCK occurred after ring assembly was complete and coincided with ring contraction. MLCK inhibition slowed and then stopped contraction but did not prevent ring assembly. MLCK inhibition also delayed barrier function recovery. Studies of human colonic biopsy specimens suggest that purse-string wound closure also occurs in vivo, because MLC phosphorylation was enhanced surrounding oligocellular wounds. CONCLUSIONS: These results suggest complementary roles for these kinases in purse-string closure of experimental and in vivo oligocellular epithelial wounds; rho and ROCK are critical for actin ring assembly, while the activity of MLCK drives contraction.

Actin Cytoskeleton↗

PubMed1995

The transient behaviour of models of bowed-string motion.

Theoretical models of the action of a bowed string may be able to shed light on differences of "playability" between different violins. Subjective judgements seem to be concerned, at least in part, with the robustness with which one particular oscillation regime of the string (the "Helmholtz motion") may be obtained under different bowing conditions. In this paper, after a review of bowed-string modelling, systematic simulation is used to obtain plots of the basin of attraction of the Helmholtz motion in a particular subspace of the player's control space. Variations in the size and structure of this basin of attraction are seen when parameters of the problem are varied, and some physical interpretation of these variations is given. Some parallels and contrasts are pointed out between the particular features of the bowed string as a nonlinear system, and the range of more familiar dynamical systems. (c) 1995 American Institute of Physics.

Journal Article↗

PubMed2005

A growing string method for the reaction pathway defined by a Newton trajectory.

The reaction path is an important concept of theoretical chemistry. We use a projection operator for the following of the Newton trajectory (NT) along the reaction valley of the potential energy surface. We describe the numerical scheme for the string method, adapting the proposal of a growing string (GS) by [Peters et al.,J. Chem. Phys. 120, 7877 (2004)]. The combination of the Newton projector and the growing string idea is an improvement of both methods, and a great saving of the number of iterations needed to find the pathway over the saddle point. This combination GS-NT is at the best of our knowledge new. We employ two different corrector methods: first, the use of projected gradient steps, and second a conjugated gradient method, the CG+ method of Liu, Nocedal, and Waltz, generalized by projectors. The executed examples are Lennard-Jones clusters, LJ(7) and LJ(22), and an N-methyl-alanyl-acetamide (alanine dipeptide) rearrangement between the minima C7(ax) and C5. For the latter, the growing string calculation is interfaced with the GASSIAN03 quantum chemical software package.

Journal Article↗

PubMed1996

Healing of incisional wounds in the embryonic chick wing bud: characterization of the actin purse-string and demonstration of a requirement for Rho activation.

Small skin wounds in the chick embryo do not heal by lamellipodial crawling of cells at the wound edge as a skin wound does in the adult, but rather by contraction of an actin purse-string that rapidly assembles in the front row of epidermal cells (Martin, P., and J. Lewis. 1992. Nature (Lond.). 360:179-183). To observe the early time course of actin purse-string assembly and to characterize other cytoskeletal components of the contractile machinery, we have followed the healing of incisional or slash wounds on the dorsum of the chick wing; these wounds take only seconds to create and heal within approximately 6 h. Healing of the epithelium depends on a combination of purse-string contraction and zipper-like closure of the gap between the cut edges of the epithelium. Confocal laser scanning microscope studies show that actin initially aligns into a cable at the wound margin in the basal layer of the epidermis within approximately 2 min of wounding. Coincident with actin cable assembly, we see localization of cadherins into clusters at the wound margin, presumably marking the sites where segments of the cable in adjacent cells are linked via adherens junctions. A few minutes later we also see localization of myosin II at the wound margin, as expected if myosin is being recruited into the cable to generate a contractile force for wound healing. At the time of wounding, cells at the wound edge become transiently leaky, allowing us to load them with reagents that block the function of two small GTPases, Rho and Rac, which recently have been shown to play key roles in reorganiztion of the actin cytoskeleton in tissue-culture cells (Hall, A. 1994. Annu. Rev. Cell Biol. 10:31-54). Loading wound edge epidermal cells with C3 transferase, a bacterial exoenzyme that inactivates endogenous Rho, prevents assembly of an actin cable and causes a failure of healing. No such effects are seen with N17rac, a dominant inhibitory mutant Rac protein. These findings support the view that in this system the actin cable is required for healing-both the purse-string contraction and the zipping up-and that Rho is required for formation of the actin cable.

ADP Ribose Transferases↗

PubMed1995

Reconstructing strings from substrings.

We consider an interactive approach to DNA sequencing by hybridization, where we are permitted to ask questions of the form "is s a substring of the unknown sequence S?", where s is a specific query string. We are not told where s occurs in S, nor how many times it occurs, just whether or not s a substring of S. Our goal is to determine the exact contents of S using as few queries as possible. Through interaction, far fewer queries are necessary than using conventional fixed sequencing by hybridization (SBH) sequencing chips. We provide tight bounds on the complexity of reconstructing unknown strings from substring queries. Our lower bound, which holds even for a stronger model that returns the number of occurrence of s as a substring of S, relies on interesting arguments based on de Bruijn sequences. We also demonstrate that subsequence queries are significantly more powerful than substring queries, matching the information theoretic lower bound. Finally, in certain applications, something may already be known about the unknown string, and hence it can be determined faster than an arbitrary string. We show that building an optimal decision tree is NP-complete, then give an approximation algorithm that gives trees within a constant multiplicative factor of optimal.

Algorithms↗

PubMed2002

Wound closure in the lamellipodia of single cells: mediation by actin polymerization in the absence of an actomyosin purse string.

The actomyosin purse string is an evolutionarily conserved contractile structure that is involved in cytokinesis, morphogenesis, and wound healing. Recent studies suggested that an actomyosin purse string is crucial for the closure of wounds in single cells. In the present study, morphological and pharmacological methods were used to investigate the role of this structure in the closure of wounds in the peripheral cytoplasm of sea urchin coelomocytes. These discoidal shaped cells underwent a dramatic form of actin-based centripetal/retrograde flow and occasionally opened and closed spontaneous wounds in their lamellipodia. Fluorescent phalloidin staining indicated that a well defined fringe of actin filaments assembles from the margin of these holes, and drug studies with cytochalasin D and latrunculin A indicated that actin polymerization is required for wound closure. Additional evidence that actin polymerization is involved in wound closure was provided by the localization of components of the Arp2/3 complex to the wound margin. Significantly, myosin II immunolocalization demonstrated that it is not associated with wound margins despite being present in the perinuclear region. Pharmacological evidence for the lack of myosin II involvement in wound closure comes from experiments in which a microneedle was used to produce wounds in cells in which actomyosin contraction was inhibited by treatment with kinase inhibitors. Wounds produced in kinase inhibitor-treated cells closed in a manner similar to that seen with control cells. Taken together, our results suggest that an actomyosin purse string mechanism is not responsible for the closure of lamellar wounds in coelomocytes. We hypothesize that the wounds heal by means of a combination of the force produced by actin polymerization alone and centripetal flow. Interestingly, these cells did assemble an actomyosin structure around the margin of phagosome-like membrane invaginations, indicating that myosin is not simply excluded from the periphery by some general mechanism. The results indicate that the actomyosin purse string is not the only mechanism that can mediate wound closure in single cells.

Actins↗