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Stevenson, B. R., M. B. Heintzelman, J. M. Anderson, S. Citi y M. S. Mooseker. "ZO-1 and cingulin: tight junction proteins with distinct identities and localizations". American Journal of Physiology-Cell Physiology 257, n.º 4 (1 de octubre de 1989): C621—C628. http://dx.doi.org/10.1152/ajpcell.1989.257.4.c621.
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The relative localization of ZO-1 and cingulin, the only two known components of the tight junction, was compared in Madin-Darby canine kidney (MDCK) cells, chicken small intestine, rat kidney distal convoluted tubule, and a hepatoma cell line. Immunoblot analysis demonstrated that cingulin and ZO-1 are immunologically unrelated and that, in the colon, cingulin is a single polypeptide with a molecular mass of 140 kDa. Immunofluorescent localization of cingulin and ZO-1 in confluent monolayers of MDCK cells showed identical staining patterns. However, subconfluent MDCK cells showed distinct localizations of the two proteins. Both cingulin and ZO-1 were found at the plasma membrane only at areas of cell-cell contact, but cingulin was diffusely distributed within the cytoplasm, whereas ZO-1 showed a more clustered internal arrangement. Cingulin and ZO-1 were identically localized at the plasma membrane of hepatoma tissue culture (HTC) cells at sites of cell-cell contact. In chicken intestine examined at the ultrastructural level, immunogold particles associated with cingulin were found approximately three times farther from the junctional membrane than those affiliated with ZO-1.
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Abbass, M., G. Gilmore, A. Chalil, BG Santyr, AG Parrent, KW MacDougall y JC Lau. "P.124 Subnuclear contact localization within the subthalamic nucleus in deep brain stimulation for Parkinson Disease". Canadian Journal of Neurological Sciences / Journal Canadien des Sciences Neurologiques 49, s1 (junio de 2022): S41. http://dx.doi.org/10.1017/cjn.2022.215.
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Background: Therapeutic response from subthalamic nucleus (STN) deep brain stimulation (DBS) for Parkinson disease (PD) has been associated with proximity to an ideal target, commonly in the dorsal sensorimotor STN. Automated registration and atlas-based segmentation has allowed for contact localization within STN subnuclei. We sought to apply these methods to characterize the spatial distribution of our active contact placements. Methods: We conducted a retrospective analysis of 55 patients who underwent bilateral STN DBS for PD. Post-operative CT/MRI scans were non-linearly registered into a standard space, and DBS-electrodes were localized using Lead-DBS. 3-dimensional meshes from a segmented atlas (Ewert 2017) were utilized. Analysis was performed in MATLAB R2019b. Results: Mean active contacts were within sensorimotor STN bilaterally, located posteroinferiorly compared to reported ideal targets. Centroids fell within (left/right): sensorimotor (46%/40%), associative (22%/22%), limbic (0%/2%) and outside STN (32%/36%). Principal components analysis demonstrated most spatial variance is explained by the first component (left 65.8%, right 61.9%). Conclusions: We obtained contact locations in relation to STN subnuclei, allowing for an anatomically guided approach to our analysis. 66% of the active contacts were located within the STN, and most of the spatial variation occurred along a single dimension. Future directions include utilizing subnuclei localizations to investigate clinical outcomes.
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Lai, Van-Vuong, Igor Paszkiewicz, Jean-François Brunel y Philippe Dufrénoy. "Multi-Scale Contact Localization and Dynamic Instability Related to Brake Squeal". Lubricants 8, n.º 4 (6 de abril de 2020): 43. http://dx.doi.org/10.3390/lubricants8040043.
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Friction-induced vibrations (brake squeal) produced during braking applications have been one of the major problems in the transportation for many years. It can be the most troublesome for passengers because of its high frequency and acoustic pressure. The role of frictional contact surface geometry on the occurrence of squeal was investigated recently by some researchers. However, it has never been systematically studied at different scales simultaneously. Contact localizations are induced on the one hand by macro effects such as thermal dilatation (macroscopic scale) and on the other hand, by the heterogeneity of third body (tribolayer) generated by friction (mesoscopic scale). The aim of this paper is to investigate the effect of contact localization at both scales through stability analysis on a simplified pad on disc system. The model has been developed numerically by the finite element method (FEM) to introduce a non-uniform contact at macroscopic and mesoscopic scales. The results showed a strong dependency between squeal frequencies and effective contact zone at macroscopic and mesoscopic scales for the investigated configuration. Especially, it is found that squeal frequencies depend on the contact area at a macroscopic scale whereas the probability of occurrence of squeal frequency strongly relies on mesoscopic contact distribution.
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Pöllänen, J., O. Saksela, EM Salonen, P. Andreasen, L. Nielsen, K. Danø y A. Vaheri. "Distinct localizations of urokinase-type plasminogen activator and its type 1 inhibitor under cultured human fibroblasts and sarcoma cells". Journal of Cell Biology 104, n.º 4 (1 de abril de 1987): 1085–96. http://dx.doi.org/10.1083/jcb.104.4.1085.
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We studied the immunocytochemical localization of urokinase-type plasminogen activator (u-PA) and the type 1 plasminogen activator inhibitor (PAI-1) in human fibroblasts and sarcoma cells, using both polyclonal and monoclonal antibodies. The u-PA was found to be located at discrete cell-substratum contact sites, and also at areas of cell-cell contacts, whereas PAI-1 was distributed as a homogeneous carpet excluding strialike areas on the substrate under the cells. To confirm the extracellular localization of u-PA and PAI-1, we stained the cells live at 0 degree C before fixation. A double-labeling experiment showed different distribution of u-PA and PAI-1 under the cells, and especially their peripheral parts. The staining pattern of u-PA and PAI-1 resisted treatment with 0.2% saponin followed by mechanical removal of cells, a method previously reported to isolate focal contact membranes of fibroblasts. We further demonstrated the deposition of u-PA to the contact areas of cells obtained by saponin treatment by zymography, and that of PAI-1 by metabolic labeling, reverse zymography, immunoblotting, and immunoprecipitation. Fibronectin was also present in the preparations. The deposition of both PAI-1 and fibronectin by the sarcoma cells was enhanced, after treating the cells with 10(-6) M dexamethasone. The confinement of u-PA to discrete contact sites and the more uniform distribution of PAI-1 on the cell substratum may explain how cells producing large amounts of enzyme inhibitors can produce PA-mediated focal proteolysis.
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Pöllänen, J., K. Hedman, L. S. Nielsen, K. Danø y A. Vaheri. "Ultrastructural localization of plasma membrane-associated urokinase-type plasminogen activator at focal contacts." Journal of Cell Biology 106, n.º 1 (1 de enero de 1988): 87–95. http://dx.doi.org/10.1083/jcb.106.1.87.
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We have recently shown that urokinase-type plasminogen activator (u-PA) and plasminogen activator inhibitor type 1 are both found extracellularly beneath cultured human skin fibroblasts and HT-1080 sarcoma cells, but in distinct localizations. Here, the ultrastructural distribution of u-PA was studied using immunoferritin electron microscopy. In HT-1080 cells, u-PA on the extracellular aspect of the plasma membrane was detected at sites of direct contact of the cell with the growth substratum beneath all parts of the ventral cell surface. The ferritin-labeled adhesion plaques, which were enriched in submembraneous microfilaments, were frequently seen at the leading lamellae of the cells as well as in lamellipodia and microspikes. Besides the cell-substratum adhesion plaques, ferritin label was detected at cell-cell contact sites. Double-label immunofluorescence showed a striking colocalization of u-PA and vinculin in both HT-1080 cells and WI-38 lung fibroblasts, which is consistent with u-PA being a focal contact component. The u-PA-containing focal contacts of WI-38 cells had no direct codistribution with fibronectin fibrils. In WI-38 cells made stationary by cultivation in a medium containing 0.5% FCS, vinculin plaques became highly elongated and more centrally located, whereas u-PA immunolabel disappeared from such focal adhesions. These findings show that plasma membrane-associated u-PA is an intrinsic component of focal contacts, where, we propose, it enables directional proteolysis for cell migration and invasion.
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Gao, Mingming y Hongyuan Yang. "VPS13: A lipid transfer protein making contacts at multiple cellular locations". Journal of Cell Biology 217, n.º 10 (4 de septiembre de 2018): 3322–24. http://dx.doi.org/10.1083/jcb.201808151.
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The evolutionarily conserved VPS13 proteins localize to multiple membrane contact sites though their function and regulation has been elusive. Bean et al. (2018. J. Cell Biol. https://doi.org/10.1083/jcb.201804111) found that competitive adaptors control the different localizations of yeast Vps13p, while Kumar et al. (2018. J. Cell Biol. https://doi.org/10.1083/jcb.201807019) provide biochemical and structural evidence for VPS13 proteins in the nonvesicular transport of phospholipids.
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Bolivar, I. y J. Guiard-Maffia. "Cellular localization of the SerH surface antigen in Tetrahymena thermophila". Journal of Cell Science 94, n.º 2 (1 de octubre de 1989): 343–54. http://dx.doi.org/10.1242/jcs.94.2.343.
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We have purified the SerH surface antigen of T. thermophila by a novel and simple procedure and produced specific antisera against it. By the use of various immunochemical techniques, we have investigated the intracellular distribution of the antigen and shown that SerH is not only abundant in the cortex but also in the digestive apparatus of the ciliate. In each of these two localizations, SerH occupies a variety of compartments: in the cortex it can be found in the surface coat, the exocytotic mucocysts, the endocytotic parasomal sacs and as an integral protein of the membrane; in the digestive apparatus, SerH is found around ingested bacteria, in the cytoplasm surrounding the cytopharynx and the forming food vacuoles, and, seemingly, as a membrane-associated protein in young food vacuoles. Pulse-chase experiments have shown that feeding dramatically increases the global turnover of SerH. Besides these localizations, SerH is principally found in clumps around dense intracytoplasmic spheres, which could be mucocyst precursors. Indirect evidence is presented that SerH is routed to the peripheral or extracellular compartments via the mucocysts. The antigen is absent from alveolar, nuclear or mitochondrial membranes. We propose that SerH covers any membrane in contact or future contact with the extracellular medium.
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Ndour, Mamour y Birahim Gueye. "Mlouma: to connect the agricultural products market players". Emerald Emerging Markets Case Studies 6, n.º 3 (28 de septiembre de 2016): 1–18. http://dx.doi.org/10.1108/eemcs-10-2016-0276.
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Subject area Social entrepreneurship/social innovation. Study level/applicability This real case targets license and master’s students as part of an ongoing course on social entrepreneurship, social innovation, in one word, on entrepreneurship. Case overview Mlouma is a platform based on Web, SMS, USSD, mobile application and call center. This social enterprise keeps farmers in contact with food buyers by displaying real-time market prices and localizations. The service will improve the efficiency of the agriculture supply chain, helping farmers to get a better price for their product. By introducing information and communication technology, Mlouma provides innovative solutions to the market failure by creating more value for producers and consumers. Expected learning outcomes This case shows the importance of the entrepreneurial orientation of social enterprises to adapt to its context and discuss theory of social entrepreneurship. Supplementary materials Teaching Notes are available for educators only. Please contact your library to gain login details or email support@emeraldinsight.com to request teaching notes. Subject code CSS 3: Entrepreneurship.
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Arango-Argoty, G. A., J. A. Jaramillo-Garzón y G. Castellanos-Domínguez. "Feature extraction by statistical contact potentials and wavelet transform for predicting subcellular localizations in gram negative bacterial proteins". Journal of Theoretical Biology 364 (enero de 2015): 121–30. http://dx.doi.org/10.1016/j.jtbi.2014.08.051.
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Frangieh, Joseph, Yannick Desplanques, Ruddy Mann y Philippe Dufrenoy. "Downscaling for disc-brake wear testing using a thermomechanical approach". Mechanics & Industry 24 (2023): 24. http://dx.doi.org/10.1051/meca/2023016.
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Brake wear has been identified to be an important source of non-exhaust emissions in transportation. The high dissipated energy in the contact not only results in large frictional heat dissipation in the brake components but also in the generation of debris, particles and gases produced by the wear of both pads and disc. Numerical simulation or tribological tests at the material scale are still not sufficient to predict wear. Experiments at the original scale of the brake system are necessary, with a significant implementation time, high costs and with a limited scope. The aim of the present work is a downscaling strategy to design experiments at reduced scale (i.e. pin-on-disc tribometer scale) taking care of the thermomechanical characteristics of the full-scale braking situation in the case of a railway application. This approach requires a complete understanding of the thermomechanical processes occurring during braking, with respect to the contact loading, the thermal localizations (migrating hot bands), the kinematics of contact opening and closing, and the couplings with the tribological circuit and the wear processes. Their apprehension is based on tests carried out on a full-scale bench equipped with the studied railway brake. A numerical model has been developed to interpret the experiment with respect to the kinetics of contact location and opening-closing, and to identify the relative determinants, key to wear. The transposition of the brake configuration to the tribometer configuration is based on these determinants in the design of a wear-preserving tribosystem. For example, the design of the disc has been adjusted on the reduced scale pin-on-disc system to fit with the kinetical parameters of contact location previously described related to the wear determinants.
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Kazancioglu, Rumeyza, Banu Buyukaydin, Meryem Iraz, Murat Alay y Reha Erkoc. "An unusual cause of peritonitis in peritoneal dialysis patients: Pantoea agglomerans". Journal of Infection in Developing Countries 8, n.º 07 (14 de julio de 2014): 919–22. http://dx.doi.org/10.3855/jidc.3785.
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Peritonitis is a serious infection and early diagnosis and treatment is mandatory. A variety of microorganisms are identified in these cases and during recent years a new one was included, Pantoea agglomerans. In this case report, a female patient on continuous ambulatory peritoneal dialysis therapy with a peritonitis episode caused by this organism is described. The source of infection was thought to be due to contact of catheter with non-sterile surfaces. In microbiologic culture, this organism was identified and the patient successfully treated with a three week course of gentamicin therapy. The number of reported cases with this organism has increased in last years and various infection localizations and clinical progress patterns have been identified. In peritoneal dialysis patients presenting with peritonitis, this organism must be kept in mind.
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Soper, Daniel J., Dustine Reich, Alex Ross, Pariya Salami, Sydney S. Cash, Ishita Basu, Noam Peled y Angelique C. Paulk. "Modular pipeline for reconstruction and localization of implanted intracranial ECoG and sEEG electrodes". PLOS ONE 18, n.º 7 (7 de julio de 2023): e0287921. http://dx.doi.org/10.1371/journal.pone.0287921.
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Implantation of electrodes in the brain has been used as a clinical tool for decades to stimulate and record brain activity. As this method increasingly becomes the standard of care for several disorders and diseases, there is a growing need to quickly and accurately localize the electrodes once they are placed within the brain. We share here a protocol pipeline for localizing electrodes implanted in the brain, which we have applied to more than 260 patients, that is accessible to multiple skill levels and modular in execution. This pipeline uses multiple software packages to prioritize flexibility by permitting multiple different parallel outputs while minimizing the number of steps for each output. These outputs include co-registered imaging, electrode coordinates, 2D and 3D visualizations of the implants, automatic surface and volumetric localizations of the brain regions per electrode, and anonymization and data sharing tools. We demonstrate here some of the pipeline’s visualizations and automatic localization algorithms which we have applied to determine appropriate stimulation targets, to conduct seizure dynamics analysis, and to localize neural activity from cognitive tasks in previous studies. Further, the output facilitates the extraction of information such as the probability of grey matter intersection or the nearest anatomic structure per electrode contact across all data sets that go through the pipeline. We expect that this pipeline will be a useful framework for researchers and clinicians alike to localize implanted electrodes in the human brain.
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Mordyk, A. V., A. A. Turitsa, A. V. Kondrya, Anna R. Aroyan y E. A. Tsygankova. "Identification of different shapes and localizations of tuberculosis in children of different ages: the role of screening examination". Russian Pediatric Journal 19, n.º 3 (30 de abril de 2019): 151–56. http://dx.doi.org/10.18821/1560-9561-2016-19-3-151-156.
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There was performed an analysis of the age structure of clinical forms of tuberculosis in children aged from 0 to 14 years. The most favorable structure of clinicalforms in children ofpreschool age was established to be characterized by absolute predominance of tuberculosis of intrathoracic lymph nodes (TILN), the minimum number of complications and generalized processes. The greatest number of the diseasedfor the 25-year period of observation was consisted of children ofprimary school age. The main method of detection of tuberculosis in children remained to be screening annual examination with the use of Mantoux test with 2 ТЕ PPD-L, in this way there were revealed 48% of all tuberculosis cases in children and 63,9% of cases of TILN. Extrapulmonary and generalized tuberculosis more frequently was revealed at the request for medical care and on contact, tuberculosis of the urinary system in 39,5% was revealed during examination of risk groups.
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Mester, Bastian, Patric Kröpil, Tobias Gensior, Tobias Ohmann y Christian Schoepp. "Do localization and appeareance of bone bruise influence the subjective short-term outcome after ACL reconstruction?" Orthopaedic Journal of Sports Medicine 8, n.º 5_suppl4 (1 de mayo de 2020): 2325967120S0029. http://dx.doi.org/10.1177/2325967120s00291.
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Aims and Objectives: Large external forces in anterior cruciate ligament (ACL) injury mechanisms cause a traumatic impact between femur and tibia. Apart from concomitant intraarticular injuries like meniscal tears and chondral lesions, MRI shows a high prevalence of femorotibial bone bruise (BB) without the arthroscopic proof of macroscopic chondral defects. In recent literature, controversial results are described concerning the association between BB and subjective outcome after ACL injury. There is very limited data for the results following ACL reconstruction. Aim of this study is the evaluation of the influence of localization and appeareance of BB in isolated ACL injuries on the subjective outcome of ACL reconstruction within the first year after surgery. Materials and Methods: This study is an analysis of preoperative MRI and prospectively collected subjective functional scores in 55 patients (sex m:f = 38:17; age 33,71±11,46 years; BMI 26,08±3,44) with isolated ACL injuries without concomitant intraarticular pathologies. These patients were treated between 09/15 and 11/17 by arthroscopic ACL reconstruction with ipsilateral hamstrings. MRI evaluation was performed blinded and independently by a radiologist and a surgeon. BB was diffentiated by 8 localizations: medial/lateral femoral condyle und tibial plateau, anteriorly and posteriorly each (MFA, MFP, LFA, LFP, MTA, MTP, LTA, LTP). Classification of appeareance was done according to Costa-Paz et al. (type I-III). Demographic data and injury mechanisms were collected. Finally, localization and appeareance of BB were analyzed statistically with regard to an impact on subjective functional outcome measures - Lysholm Score (LS) and Tegner Activitiy Scale (TAS) - before surgery (t0) and at four follow-up examinations (t1-t4 within one year after ACL reconstruction. Results: The time between injury and MRI was 35,09±94,52 days, between injury and surgery 96,09±120,75 days. In 80% (n=44) non-contact injury mechanisms could be detected, sports injuries in most cases (60%). BB was found in 94,4% (n=51), the most frequent localizations were LTP (74,5%, n=41) and LFA (56,4%, n=31). A singular femoral BB could not be found. Concerning the appeareance, distribution was shown as followed: n=18 (32,7%) type I, n=26 (47,3%) type II, n=7 (12,7%) type III. In n=6 MRI revealed a depression of the lateral femoral condyle (“lateral femoral notch sign”). For the whole cohort (independently from BB) we could demonstrate a highly significant improvement for LS and TAS over time (t0/t1-t4; ANOVA, p<0,001). Neither localization nor appeareance of BB had a significant impact on LS or TAS for t0-t4. Conclusion: In conclusion, the results of the existing literature for incidence and distribution of BB in ACL injuries are confirmed. Our own data showed no influence of BB on the subjective short-term outcome following ACL reconstruction within the first year after surgery. Further studies with longer follow-up period (>2 years) and volumetric BB measurement are in preparation.
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Chew, Catherine S., Curtis T. Okamoto, Xunsheng Chen y Hai Yan Qin. "IQGAPs are differentially expressed and regulated in polarized gastric epithelial cells". American Journal of Physiology-Gastrointestinal and Liver Physiology 288, n.º 2 (febrero de 2005): G376—G387. http://dx.doi.org/10.1152/ajpgi.00290.2004.
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IQGAPs, GTPase-activating proteins with an IQ motif, are thought to regulate many actin cytoskeleton-based activities through interactions with Cdc42 and Rac. Recently, Cdc42 was implicated in regulation of gastric parietal cell HCl secretion, and IQGAP2 was immunolocalized with Cdc42 to F-actin-rich intracellular canalicular membranes of isolated gastric parietal cells in primary culture. Here we sought to define distribution and localization of IQGAP1 and IQGAP2 in major oxyntic (acid-secreting) gastric mucosal cell types and to determine whether secretory agonists modulate these proteins. Differential staining protocols were used to identify different cell populations (parietal, chief, surface/pit, and mucous neck cells) in semi-intact glands isolated from rabbit gastric mucosae and to characterize these same cells after dispersion and fractionation on isopycnic density gradients with simultaneous staining for F-actin, H+-K+-ATPase, and GSII lectin-binding sites. There was a pronounced increase in intracellular F-actin staining in dispersed chief cells, apparently from internalization of F-actin-rich apical membranes that normally abut the gland lumen. Therefore, other membrane-associated proteins might also be redistributed by disruption of cell-cell contacts. Western blot analyses were used to quantitate relative concentrations of IQGAPs in defined mucosal cell fractions, and gastric glands were used for in situ localizations. We detected uniform levels of IQGAP2 expression in oxyntic mucosal cells with predominant targeting to regions of cell-cell contact and nuclei of all cell types. IQGAP2 was not detected in parietal cell intracellular canaliculi. IQGAP1 expression was variable and targeted predominantly to the cortex of chief and mucous neck cells. Parietal cells expressed little or no IQGAP1 vs. other mucosal cell types. Phosphoprotein affinity chromatography, isoelectric focusing, and phosphorylation site analyses indicated that both IQGAP1 and IQGAP2 are phosphoproteins potentially regulated by [Ca2+]i/PKC and cAMP signaling pathways, respectively. Stimulation of glands with carbachol, which elevates [Ca2+]i and activates PKC, induced apparent translocation of IQGAP1, but not IQGAP2, to apical poles of chief (zymogen) and mucous neck cells. This response was mimicked by PMA but not by ionomycin or by elevation of [cAMP]i with forskolin. Our observations support a novel, PKC-dependent role for IQGAP1 in regulated exocytosis and suggest that IQGAP2 may play a more general role in regulating cell-cell interactions and possibly migration within the gastric mucosa.
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de Gabory, L., R. Bareille, R. Daculsi, R. Daculsi, B. J. L. Azou, E. Flahaut y L. Bordenave. "Carbon nanotubes have a deleterious effect on the nose: the first in vitro data". Rhinology journal 49, n.º 4 (1 de octubre de 2011): 445–52. http://dx.doi.org/10.4193/rhino10.256.
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Background: The information currently available concerning carbon nanotubes toxicity is disturbing and conflicting. Moreover, little is known about their effect on the nasal cavities, which are the first target for nanoparticles. Material and method: We investigated the cytotoxicity (50 to 0.5 microg/mL) of double-walled carbon nanotube with two independent tests (MTT, Wst-1) on normal human nasal epithelial cells after 12-day exposure (control untreated nasal cells and A549). Nasal cell differentiation function, oxidative stress, the morphological features of cells in contact with DWCNTs and the localizations of the latter were also investigated. Results: Exposure revealed a dose-dependent decrease in cell metabolic activity and cell growth. In nearly all conditions, normal human nasal epithelial cells were more sensitive than malignant ones. Even with both tests, the cytotoxic threshold dose could not be accurately determined because of dye adsorption by DWCNTs. Nasal cells showed stronger cytokeratin 7 and persistent UEA-I immunostaining. Cytokeratin 19 production was increased at 25 microg/mL and mucus production was stimulated from 0.5 microg/mL. A significant increase in Reactive Oxygen Species was observed from 25 microg/mL. The cell plasma membrane showed several holes and DWCNTs were present in the cytoplasm. Conclusion: DWCNTs seem to have a deleterious effect on nasal cells after 12-day exposure.
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Wan, Chang-Feng, Li-Gang Sun, Hai-Long Qin, Zhong-Nan Bi y Dong-Feng Li. "A Molecular Dynamics Study on the Dislocation-Precipitate Interaction in a Nickel Based Superalloy during the Tensile Deformation". Materials 16, n.º 18 (9 de septiembre de 2023): 6140. http://dx.doi.org/10.3390/ma16186140.
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In the present paper, the dislocation-precipitate interaction in the Inconel 718 superalloy is studied by means of molecular dynamics simulation. The atomistic model composed of the ellipsoidal Ni3Nb precipitate (γ″ phase) and the Ni matrix is constructed, and tensile tests on the composite Ni3Nb@Ni system along different loading directions are simulated. The dislocation propagation behaviors in the precipitate interior and at the surface of the precipitate are characterized. The results indicate that the dislocation shearing and bypassing simultaneously occur during plastic deformation. The contact position of the dislocation on the surface of the precipitate could affect the penetration depth of the dislocation. The maximum obstacle size, allowing for the dislocation shearing on the slip planes, is found to be close to 20 nm. The investigation of anisotropic plastic deformation behavior shows that the composite system under the loading direction along the major axis of the precipitate experiences stronger shear strain localizations than that with the loading direction along the minor axis of the precipitate. The precipitate size effect is quantified, indicating that the larger the precipitate, the lower the elastic limit of the flow stress of the composite system. The dislocation accumulations in the precipitate are also examined with the dislocation densities given on specific slip systems. These findings provide atomistic insights into the mechanical behavior of nickel-based superalloys with nano-precipitates.
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Zenchenko, S. S. "Generation of interference in the surface layer at horizontal sounding of sea surface by infrared sight channels and devices". Transactions of the Krylov State Research Centre 2, n.º 404 (6 de junio de 2023): 158–64. http://dx.doi.org/10.24937/2542-2324-2023-2-404-158-164.
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Object and purpose of research. The object of investigation is specific temperatures at the water/air interface (skin layer of water). The purpose is to study the interrelation of dynamics in humidity variations of surface atmospheric layer and particulars of the media interface. Subject matter and methods. Infrared thermal imagers are employed with monitoring of the parameters of atmospheric layer adjacent to ocean surface using a multi-channel thermal hygrometer and contact temperature sensors placed in water and near-water air layer. Laboratory rigs of different scales simulating various levels of external factors and an open water basin were used. Main results. Consistent analysis is done regarding phase-wise measurement of skin water layer characteristics, specific structure of temperature field in IR band of spectrum under laboratory and large-scale conditions, variations of humidity content at different state of skin water layer in the process of interaction between two media. Measurements of the radiation fog of different scales are taken, which possibly forms the false and real horizons being one of the interferences for transmission of IR radiation to recording channels. Parameters and specific manifestation of this interference are measured. Conclusion. Based on the analysis and experiments it is confirmed that there are abnormal localizations of humidity content of different scales, which produce radiation temperature variations.
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Briesewitz, R., A. Kern y E. E. Marcantonio. "Ligand-dependent and -independent integrin focal contact localization: the role of the alpha chain cytoplasmic domain." Molecular Biology of the Cell 4, n.º 6 (junio de 1993): 593–604. http://dx.doi.org/10.1091/mbc.4.6.593.
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Many integrin receptors localize to focal contact sites upon binding their ligand. However, unoccupied integrin receptors do not localize to focal contact sites. Because the integrin beta 1 cytoplasmic domain appears to have a focal contact localization signal, there must be a mechanism by which this domain is kept inactive in the unoccupied state and becomes exposed or activated in the occupied receptor. We considered that this mechanism involves the alpha subunit cytoplasmic domain. To test this hypothesis, we have established two NIH 3T3 cell lines that express either the human alpha 1 wild-type subunit (HA1 cells) or the cytoplasmic domain deleted alpha 1 subunit (CYT cells). Both cell lines express similar levels of the human alpha 1 subunit, and there is no significant effect of the deletion on the dimerization and surface expression of the receptor. Furthermore, the deletion had no effect on the binding or adhesion via alpha 1 beta 1 to its ligand collagen IV. However, when these two cell lines are plated on fibronectin (FN), which is a ligand for alpha 5 beta 1 but not for alpha 1 beta 1, there is a striking difference in the cellular localization of alpha 1 beta 1. The HA1 cells show only alpha 5 in focal contacts, without alpha 1, demonstrating that all of the integrin localization is ligand dependent. In contrast, when the CYT cells are plated on FN, the mutant alpha 1 appears in focal contacts along with the alpha 5/beta 1. Thus, there is both ligand-dependent (alpha 5/beta 1) and ligand-independent (alpha 1/beta 1) focal contact localization in these cells. The truncated alpha 1 also localized to focal contacts in a ligand-independent manner on vitronectin. We conclude that the mutant alpha 1 no longer requires ligand occupancy for focal contact localization. These data strongly suggest that the alpha cytoplasmic domain plays a role in the normal ligand-dependent integrin focal contact localization.
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Krüger-Genge, Blocki, Franke y Jung. "Vascular Endothelial Cell Biology: An Update". International Journal of Molecular Sciences 20, n.º 18 (7 de septiembre de 2019): 4411. http://dx.doi.org/10.3390/ijms20184411.
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The vascular endothelium, a monolayer of endothelial cells (EC), constitutes the inner cellular lining of arteries, veins and capillaries and therefore is in direct contact with the components and cells of blood. The endothelium is not only a mere barrier between blood and tissues but also an endocrine organ. It actively controls the degree of vascular relaxation and constriction, and the extravasation of solutes, fluid, macromolecules and hormones, as well as that of platelets and blood cells. Through control of vascular tone, EC regulate the regional blood flow. They also direct inflammatory cells to foreign materials, areas in need of repair or defense against infections. In addition, EC are important in controlling blood fluidity, platelet adhesion and aggregation, leukocyte activation, adhesion, and transmigration. They also tightly keep the balance between coagulation and fibrinolysis and play a major role in the regulation of immune responses, inflammation and angiogenesis. To fulfill these different tasks, EC are heterogeneous and perform distinctly in the various organs and along the vascular tree. Important morphological, physiological and phenotypic differences between EC in the different parts of the arterial tree as well as between arteries and veins optimally support their specified functions in these vascular areas. This review updates the current knowledge about the morphology and function of endothelial cells, particularly their differences in different localizations around the body paying attention specifically to their different responses to physical, biochemical and environmental stimuli considering the different origins of the EC.
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Voigts, Jakob, David H. Herman y Tansu Celikel. "Tactile object localization by anticipatory whisker motion". Journal of Neurophysiology 113, n.º 2 (15 de enero de 2015): 620–32. http://dx.doi.org/10.1152/jn.00241.2014.
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Rodents use rhythmic protractions of their whiskers to locate objects in space. The amplitude of these protractions is reduced when whiskers contact objects, leading to a tendency of whiskers to only lightly touch the environment. While the impact of this process on the sensory input has been studied, little is known about how sensory input causes this change in the motor pattern. Here, using high-speed imaging of whisking in mice, we simultaneously measured whisker contacts and the resulting whisking motion. We found that mice precisely target their whisker protractions to the distance at which they expect objects. This modulation does not depend on the current sensory input and remains stable for at least one whisking cycle when there is no object contact or when the object position is changed. As a result, the timing and other information carried by whisker contacts encodes how well each protraction was matched to the object, functioning as an error signal. Whisker contacts can thus encode a mismatch between expected object locations and the actual environment.
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Yelnik, Jérôme, Philippe Damier, Sophie Demeret, David Gervais, Eric Bardinet, Boulos-Paul Bejjani, Chantal François et al. "Localization of stimulating electrodes in patients with Parkinson disease by using a three-dimensional atlas—magnetic resonance imaging coregistration method". Journal of Neurosurgery 99, n.º 1 (julio de 2003): 89–99. http://dx.doi.org/10.3171/jns.2003.99.1.0089.
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Object. The aim of this study was to correlate the clinical improvement in patients with Parkinson disease (PD) treated using deep brain stimulation (DBS) of the subthalamic nucleus (STN) with the precise anatomical localization of stimulating electrodes. Methods. Localization was determined by superimposing figures from an anatomical atlas with postoperative magnetic resonance (MR) images obtained in each patient. This approach was validated by an analysis of experimental and clinical MR images of the electrode, and the development of a three-dimensional (3D) atlas—MR imaging coregistration method. The PD motor score was assessed through two contacts for each of two electrodes implanted in 10 patients: the “therapeutic contact” and the “distant contact” (that is, the next but one to the therapeutic contact). Seventeen therapeutic contacts were located within or on the border of the STN, most of which were associated with significant improvement of the four PD symptoms tested. Therapeutic contacts located in other structures (zona incerta, lenticular fasciculus, or midbrain reticular formation) were also linked to a significant positive effect. Stimulation applied through distant contacts located in the STN improved symptoms of PD, whereas that delivered through distant contacts in the remaining structures had variable effects ranging from worsening of symptoms to their improvement. Conclusions. The authors have demonstrated that 3D atlas—MR imaging coregistration is a reliable method for the precise localization of DBS electrodes on postoperative MR images. In addition, they have confirmed that although the STN is the main target during DBS treatment for PD, stimulation of surrounding regions, particularly the zona incerta or the lenticular fasciculus, can also improve symptoms of PD.
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Bauer, Nicola, Ana-Violeta Fonseca, Daniel Freund, Sabine Boxberger, Joachim Oswald, Carsten Werner, Gerhard Ehninger, Martin Bornhaeuser y Denis Corbeil. "Cellular and Molecular Events Underlying the Interaction of Hematopoietic Stem and Progenitor Cells with Mesenchymal Stem Cells." Blood 106, n.º 11 (16 de noviembre de 2005): 2309. http://dx.doi.org/10.1182/blood.v106.11.2309.2309.
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Abstract Understanding the mechanisms underlying the reconstitution of the hematopoietic system after blood stem cell transplantation is of crucial importance for improving therapeutic modalities. In order to address these issues, we have recently established a novel co-culture system consisting of immuno-isolated human CD34+ hematopoietic stem and progenitor cells (HSPCs) growing on primary human mesenchymal stem cells (MSCs) as feeder layer in the presence of relevant cytokines. Here we have investigated i) the morphological modification of HSPCs induced by their interaction with MSCs; ii) the sub-cellular localization of the stem cell markers CD34 and CD133 (prominin-1) as well as other cell surface molecules potentially involved in such intercellular interaction, and iii) the intracellular pathway(s) responsible for the migration as well as the interaction of HSPCs with MSCs. The scanning electron microscopy analysis revealed that the adherent HSPCs display various morphologies; they are either round with, in some cases, the appearance of a microvillar pole or exhibit several distinct types of plasma membrane protrusions such as lamellipodium, filopodium and magnupodium. We could also observe very long and thin plasma membrane processes between adjacent HSPCs suggesting the formation of nanotubes, which have been implicated in intercellular communication. As previously reported (Giebel et al., 2004, Blood, 104:2332), the highly motile HSPCs acquire a polarized cell shape with the formation of a uropod at the rear pole and a leading edge at the front pole. The immunofluorescence analyses revealed that CD34 is randomly distributed over the entire surface of HSPCs, irrespective of their morphological shape, whereas CD133 shows various specific sub-cellular localizations, which are depending on the state of the cell. In migrating cells, CD133 is concentrated in the uropod at the rear pole, which contrasts with the enriched localization of the adhesion receptor β2 integrin in the leading edge. In HSPCs harboring other types of plasma membrane protrusions, which are in close contact with the feeder cell layer, CD133 is concentrated therein. In round adhesive cells, CD133 is located in one pole of the cell suggesting that the HSPCs are highly polarized even in the absence of plasma membrane outgrowths. Interestingly, the formation of uropod and microvillus-like structures is highly reduced in presence of Y-27632 inhibitor suggesting that the Rho GTPase/ROCK pathway is somehow involved in the polarization of HSPCs. Time lapse videomicroscopy revealed that the retraction of filopodia is also affected in Y-27632-treated HSPCs as well as their migration. Taken together, these data provide new insights regarding the molecular cell biology of HSPCs, and increase our understanding of cellular events associated with mobilization and engraftment in the context of blood stem cell transplantation.
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Khrestin A.V., Pavleino M. A. y Safonov M. S. "Changing the characteristics of contact spots when short-circuit currents flow through closed high-current electrical contacts". Technical Physics 68, n.º 1 (2023): 137. http://dx.doi.org/10.21883/tp.2023.01.55448.233-22.
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Numerical simulation of heating of the vicinity of contact spots of closed copper high-current contacts by short-circuit currents of various shapes is carried out. The relationship between the parameters of thermal and mechanical fields when heated to temperatures exceeding the recrystallization temperature of the material is established. The dynamics of changes in the sizes of elastic and plastic deformations and their localization is shown. It is revealed in which cases the results of heating the contact surroundings may differ significantly with the flow of thermally equivalent currents. Keywords: electrical contact, pulse heating, numerical calculation, welding.
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Хрестин, А. В., М. А. Павлейно y М. С. Сафонов. "Изменение характеристик контактных пятен при протекании токов короткого замыкания через замкнутые сильноточные электрические контакты". Журнал технической физики 93, n.º 1 (2023): 146. http://dx.doi.org/10.21883/jtf.2023.01.54075.233-22.
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Numerical simulation of heating of the vicinity of contact spots of closed copper high-current contacts by short-circuit currents of various shapes is carried out. The relationship between the parameters of thermal and mechanical fields when heated to temperatures exceeding the recrystallization temperature of the material is established. The dynamics of changes in the sizes of elastic and plastic deformations and their localization is shown. It is revealed in which cases the results of heating the contact surroundings may differ significantly with the flow of thermally equivalent currents.
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Sandig, Martin, Yong Rao, Chi-Hung Siu y Vitauts I. Kalnins. "Integrity of the homophilic binding site is required for the preferential localization of NCAM in intercellular contacts". Biochemistry and Cell Biology 74, n.º 3 (1 de mayo de 1996): 373–81. http://dx.doi.org/10.1139/o96-040.
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The neural cell adhesion molecule NCAM is a member of the immunoglobulin (Ig) superfamily. NCAM can undergo homophilic binding and heterophilic interactions with cell surface components and is often concentrated at sites of intercellular contact. To investigate the molecular basis of this biased surface distribution, we examined L cell transfectants expressing wild-type or mutant forms of chick NCAM-140 by laser scanning confocal microscopy. Mutant NCAMs that lacked Ig-like domains 1, 2, 4, or 5 were preferentially localized in contact regions. However, the relative concentration of these mutant NCAMs in contact sites was substantially reduced compared with wild-type NCAM. In contrast, NCAM redistribution to intercellular contacts was abolished in cells expressing mutant NCAMs that either lacked Ig-like domain 3 or contained mutations in the homophilic binding site in this domain. In heterotypic contacts between PC12 cells and L cell transfectants, colocalization of rat NCAM and chick NCAM was again dependent on the integrity of the homophilic binding site of the NCAM expressed on L cells. These results provide evidence that homophilic binding is the main mechanism by which NCAM becomes redistributed to intercellular contacts. They also implicate a role for other Ig-like domains in the accumulation of NCAM at cell–cell contacts.Key words: cell–cell adhesion, adhesion molecule, NCAM, homophilic binding, surface distribution.
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Casselmann, Lana y Jonathan M. Fisher. "Localization for $K$-contact manifolds". Journal of Symplectic Geometry 17, n.º 4 (2019): 1021–60. http://dx.doi.org/10.4310/jsg.2019.v17.n4.a3.
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Marcantonio, E. E., J. L. Guan, J. E. Trevithick y R. O. Hynes. "Mapping of the functional determinants of the integrin beta 1 cytoplasmic domain by site-directed mutagenesis." Cell Regulation 1, n.º 8 (julio de 1990): 597–604. http://dx.doi.org/10.1091/mbc.1.8.597.
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We describe here the expression of deletion mutants of the cytoplasmic domain of the avian integrin beta 1 subunit. These mutants, which contain termination codons at positions 767, 776, 791, and 800, were transfected into mouse 3T3 cells to determine which sequences were essential for localization of integrins into focal contact sites. In all cases, high-level expression of the truncated avian integrins was obtained. Heterodimers were formed between the exogenous truncated avian beta 1 subunits and endogenous mouse alpha subunits, and these heterodimers were efficiently exported to the cell surface. The longest truncated beta 1 subunit tested, which is only four amino acids shorter than the wild type, does localize to focal contacts. In contrast, beta 1 subunits with moderately long truncations of the cytoplasmic domain failed to localize to focal contacts, including one which contains the consensus sequence for tyrosine phosphorylation. Surprisingly, a mutant subunit in which the bulk of the cytoplasmic domain was missing (but the segment nearest the membrane including the dibasic residues (RR) remained) did localize weakly to focal contacts. These results implicate the peptide segment nearest to the transmembrane region in focal contact localization. In addition, mutant subunits that included this segment together with a larger portion of the cytoplasmic domain did not localize as well as the shorter form, suggesting that these cytoplasmic domain segments are defective, presumably because of abnormal folding.
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Huang, Lingqin, Sumin Pan, Xuliang Deng y Wenwen Cui. "4H-SiC Ohmic contacts formation by MoS2 layer intercalation: A first-principles study". Journal of Applied Physics 132, n.º 24 (28 de diciembre de 2022): 245702. http://dx.doi.org/10.1063/5.0122722.
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Due to the difficulty of forming a low Schottky barrier at the interface of a metal/SiC contact, preparing Ohmic contacts is still a key technical problem in developing SiC devices. In this paper, the effects of MoS2 intercalation on the interface properties of metal/SiC (Al, Ag, Ti, Au, and Mg) systems were investigated by first-principles calculation. The calculations show that all the metal/SiC contacts exhibit p-type Schottky contacts with strong Fermi level pinning (FLP) at the interfaces. After inserting a layer of MoS2, the Schottky barrier heights are significantly reduced. All the metal/MoS2/SiC systems are tuned to be n-type Ohmic contacts. By calculating and analyzing electron localization functions, projected band structure, partial density of states, and planar-averaged charge density difference, the Ohmic contact formation mechanism may be due to the saturation of dangling bonds of the SiC surface, the reduction in metal-induced gap states, the formation of interface dipole layer, and the shift of FLP position to the interface of metal/MoS2.
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Partridge, C. A., P. G. Phillips, M. J. Niedbala y J. J. Jeffrey. "Localization and activation of type IV collagenase/gelatinase at endothelial focal contacts". American Journal of Physiology-Lung Cellular and Molecular Physiology 272, n.º 5 (1 de mayo de 1997): L813—L822. http://dx.doi.org/10.1152/ajplung.1997.272.5.l813.
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The cell-surface localization and site of activation of type IV collagenases/gelatinases (matrix metalloproteinases, MMP) in bovine pulmonary microvascular endothelial (BPMVE) cells was examined. Sucrose density centrifugation of plasma membranes and immunofluorescent staining of whole cells indicated association of 72 kDa (MMP-2) and 96 kDa (MMP-9) type IV collagenase/gelatinases with the plasma membrane. Incubation of the BPMVE cells with rhodaminated MMP-9 demonstrated colocalization with beta 1-integrin, indicating incorporation into the focal contacts. The focal contacts were extracted with saponin, and associated proteolytic activity was examined by zymography. The focal contacts contained latent MMP-2, and stimulation of the cells with cytochalasin D or with 8-bromoadenosine 3',5'-cyclic monophosphate with 3-isobutyl-1-methylxanthine increased both latent and activated MMP-9 in the focal contacts. Addition of these stimuli in unconditioned culture medium did not produce this effect, indicating that the MMP-9 in focal contact extracts was derived from previously secreted enzyme. The activated metalloproteinase degraded extracellular matrix collagens and was inhibited by 1,10-phenanthroline. These findings indicate that endothelial cells release MMP into the extracellular milieu and then concentrate and activate MMP-9 from medium at the focal contacts.
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Murley, Andrew, Reta D. Sarsam, Alexandre Toulmay, Justin Yamada, William A. Prinz y Jodi Nunnari. "Ltc1 is an ER-localized sterol transporter and a component of ER–mitochondria and ER–vacuole contacts". Journal of Cell Biology 209, n.º 4 (18 de mayo de 2015): 539–48. http://dx.doi.org/10.1083/jcb.201502033.
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Organelle contact sites perform fundamental functions in cells, including lipid and ion homeostasis, membrane dynamics, and signaling. Using a forward proteomics approach in yeast, we identified new ER–mitochondria and ER–vacuole contacts specified by an uncharacterized protein, Ylr072w. Ylr072w is a conserved protein with GRAM and VASt domains that selectively transports sterols and is thus termed Ltc1, for Lipid transfer at contact site 1. Ltc1 localized to ER–mitochondria and ER–vacuole contacts via the mitochondrial import receptors Tom70/71 and the vacuolar protein Vac8, respectively. At mitochondria, Ltc1 was required for cell viability in the absence of Mdm34, a subunit of the ER–mitochondria encounter structure. At vacuoles, Ltc1 was required for sterol-enriched membrane domain formation in response to stress. Increasing the proportion of Ltc1 at vacuoles was sufficient to induce sterol-enriched vacuolar domains without stress. Thus, our data support a model in which Ltc1 is a sterol-dependent regulator of organelle and cellular homeostasis via its dual localization to ER–mitochondria and ER–vacuole contact sites.
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Sandler, A. I., S. A. Lagutin y E. A. Gudov. "Longitudinal contact localization in worm gears". Russian Engineering Research 34, n.º 7 (julio de 2014): 480–86. http://dx.doi.org/10.3103/s1068798x14070119.
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Fan, Lingzhi, Attila Sebe, Zalán Péterfi, András Masszi, Ana C. P. Thirone, Ori D. Rotstein, Hiroyasu Nakano et al. "Cell Contact–dependent Regulation of Epithelial–Myofibroblast Transition via the Rho-Rho Kinase-Phospho-Myosin Pathway". Molecular Biology of the Cell 18, n.º 3 (marzo de 2007): 1083–97. http://dx.doi.org/10.1091/mbc.e06-07-0602.
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Epithelial-mesenchymal-myofibroblast transition (EMT), a key feature in organ fibrosis, is regulated by the state of intercellular contacts. Our recent studies have shown that an initial injury of cell–cell junctions is a prerequisite for transforming growth factor-β1 (TGF-β1)-induced transdifferentiation of kidney tubular cells into α-smooth muscle actin (SMA)–expressing myofibroblasts. Here we analyzed the underlying contact-dependent mechanisms. Ca2+ removal–induced disruption of intercellular junctions provoked Rho/Rho kinase (ROK)-mediated myosin light chain (MLC) phosphorylation and Rho/ROK-dependent SMA promoter activation. Importantly, myosin-based contractility itself played a causal role, because the myosin ATPase inhibitor blebbistatin or a nonphosphorylatable, dominant negative MLC (DN-MLC) abolished the contact disruption-triggered SMA promoter activation, eliminated the synergy between contact injury and TGF-β1, and suppressed SMA expression. To explore the responsible mechanisms, we investigated the localization of the main SMA-inducing transcription factors, serum response factor (SRF), and its coactivator myocardin-related transcription factor (MRTF). Contact injury enhanced nuclear accumulation of SRF and MRTF. These processes were inhibited by DN-Rho or DN-MLC. TGF-β1 strongly facilitated nuclear accumulation of MRTF in cells with reduced contacts but not in intact epithelia. DN-myocardin abrogated the Ca2+-removal– ± TGF-β1–induced promoter activation. These studies define a new mechanism whereby cell contacts regulate epithelial-myofibroblast transition via Rho-ROK-phospho-MLC–dependent nuclear accumulation of MRTF.
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Boëx, Colette, Abdullah Al Awadhi, Rémi Tyrand, Marco V. Corniola, Astrid Kibleur, Vanessa Fleury, Pierre R. Burkhard y Shahan Momjian. "Validation of Lead-DBS β-Oscillation Localization with Directional Electrodes". Bioengineering 10, n.º 8 (28 de julio de 2023): 898. http://dx.doi.org/10.3390/bioengineering10080898.
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In deep brain stimulation (DBS) studies in patients with Parkinson’s disease, the Lead-DBS toolbox allows the reconstruction of the location of β-oscillations in the subthalamic nucleus (STN) using Vercise Cartesia directional electrodes (Boston Scientific). The objective was to compare these probabilistic locations with those of intraoperative monopolar β-oscillations computed from local field potentials (0.5–3 kHz) recorded by using shielded single wires and an extracranial shielded reference electrode. For each electrode contact, power spectral densities of the β-band (13–31 Hz) were compared with those of all eight electrode contacts on the directional electrodes. The DBS Intrinsic Template AtLas (DISTAL), electrophysiological, and DBS target atlases of the Lead-DBS toolbox were applied to the reconstructed electrodes from preoperative MRI and postoperative CT. Thirty-six electrodes (20 patients: 7 females, 13 males; both STN electrodes for 16 of 20 patients; one single STN electrode for 4 of 20 patients) were analyzed. Stimulation sites both dorsal and/or lateral to the sensorimotor STN were the most efficient. In 33 out of 36 electrodes, at least one contact was measured with stronger β-oscillations, including 23 electrodes running through or touching the ventral subpart of the β-oscillations’ probabilistic volume, while 10 did not touch it but were adjacent to this volume; in 3 out of 36 electrodes, no contact was found with β-oscillations and all 3 were distant from this volume. Monopolar local field potentials confirmed the ventral subpart of the probabilistic β-oscillations.
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Bean, Björn D. M., Samantha K. Dziurdzik, Kathleen L. Kolehmainen, Claire M. S. Fowler, Waldan K. Kwong, Leslie I. Grad, Michael Davey, Cayetana Schluter y Elizabeth Conibear. "Competitive organelle-specific adaptors recruit Vps13 to membrane contact sites". Journal of Cell Biology 217, n.º 10 (17 de julio de 2018): 3593–607. http://dx.doi.org/10.1083/jcb.201804111.
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The regulated expansion of membrane contact sites, which mediate the nonvesicular exchange of lipids between organelles, requires the recruitment of additional contact site proteins. Yeast Vps13 dynamically localizes to membrane contacts that connect the ER, mitochondria, endosomes, and vacuoles and is recruited to the prospore membrane in meiosis, but its targeting mechanism is unclear. In this study, we identify the sorting nexin Ypt35 as a novel adaptor that recruits Vps13 to endosomal and vacuolar membranes. We characterize an interaction motif in the Ypt35 N terminus and identify related motifs in the prospore membrane adaptor Spo71 and the mitochondrial membrane protein Mcp1. We find that Mcp1 is a mitochondrial adaptor for Vps13, and the Vps13–Mcp1 interaction, but not Ypt35, is required when ER-mitochondria contacts are lost. All three adaptors compete for binding to a conserved six-repeat region of Vps13 implicated in human disease. Our results support a competition-based model for regulating Vps13 localization at cellular membranes.
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Steinfeldt, T., J. Graf, J. Schneider, W. Nimphius, E. Weihe, A. Borgeat, H. Wulf y T. Wiesmann. "Histological Consequences of Needle-Nerve Contact following Nerve Stimulation in a Pig Model". Anesthesiology Research and Practice 2011 (2011): 1–9. http://dx.doi.org/10.1155/2011/591851.
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Background. Nerve stimulation can facilitate correct needle placement in peripheral regional anesthesia. The aim of this study was to determine whether the high threshold current is associated with reduced nerve injury due to fewer needle-nerve contacts compared with low current.Methods. In anaesthetized pigs, thirty-two nerves of the brachial plexus underwent needle placement at low (0.2 mA) or high current (1.0 mA). The occurrence of needle-nerve contact was recorded. After 48 hours, the nerves were analyzed for occurrence of histological changes. Nerve injury was scored ranging from 0 (no injury) to 4 (severe injury).Results. The frequency of needle-nerve contact was 94% at low compared to 6% at high current. The score was significantly higher at low (median [interquartile range] 2.0 [1.0-2.0]) compared to high current (0.0 [0.0-1.0]P=.001).Conclusions. Inflammatory responses were directly related to needle-nerve contacts. Hence, posttraumatic inflammation may be diminished using higher current for nerve localization.
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Sánchez-Mateos, P., M. R. Campanero, M. A. Balboa y F. Sánchez-Madrid. "Co-clustering of beta 1 integrins, cytoskeletal proteins, and tyrosine-phosphorylated substrates during integrin-mediated leukocyte aggregation." Journal of Immunology 151, n.º 7 (1 de octubre de 1993): 3817–28. http://dx.doi.org/10.4049/jimmunol.151.7.3817.
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Abstract The involvement of the VLA-4 integrin in an alternative leukocyte homotypic adhesion mechanism that is LFA-1/ICAM-1 independent, has been previously reported. We describe here the localization of beta 1 and alpha 4 integrin subunits at sites of cell-cell contact, on both beta 1- and alpha 4-induced aggregates of B lymphoblastoid Ramos cells. Moreover, the distribution of different VLA-alpha subunits was also examined on beta 1-induced cell aggregates of alpha 2- and alpha 4-transfected K-562 cells. Both alpha 2 and alpha 4 integrin subunits were mainly localized at sites of intercellular boundaries, suggesting a possible role for these integrins in leukocyte intercellular adhesion. The fibronectin receptor alpha 5 subunit was either diffuse throughout the plasma membrane, or displayed some accumulation at sites of cell-cell contact. Even though homotypic aggregation of U-937 cells was induced with the anti-alpha 5 P1D6 mAb, the alpha 5 subunit showed only partial redistribution to regions of cell-cell contact, compared with the complete redistribution of the alpha 4 subunit in the alpha 4-induced aggregates. The reorganization of the actin-cytoskeleton was observed at sites of intercellular boundaries in both the anti-beta 1- and anti-alpha 4-induced cell aggregates. Hence, F-actin and the cytoskeletal protein talin co-localized with beta 1 and alpha 4 integrin clusters at sites of cell-cell contact. Signal transduction during VLA-mediated homotypic cell adhesion has also been investigated. We found co-localization of beta 1 and alpha 4 subunits with tyrosine-phosphorylated proteins at cell-cell contact regions during cell aggregation. These data indicate that VLA integrin-mediated leukocyte aggregation results in clustering of beta 1-integrins at sites of cell-cell contact, together with co-localization of cytoskeletal proteins. These results also suggest that protein tyrosine phosphorylation is an important signal transduction mechanism when VLA integrins participate in intercellular contacts.
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Myöhänen, H. T., R. W. Stephens, K. Hedman, H. Tapiovaara, E. Rønne, G. Høyer-Hansen, K. Danø y A. Vaheri. "Distribution and lateral mobility of the urokinase-receptor complex at the cell surface." Journal of Histochemistry & Cytochemistry 41, n.º 9 (septiembre de 1993): 1291–301. http://dx.doi.org/10.1177/41.9.8394852.
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Pro-urokinase (pro-uPA) and activated uPA are confined to focal adhesions and cell-cell contacts. We studied the distribution of the uPA receptor (uPAR) on human fibroblasts (HES) and rhabdomyosarcoma (RD) cells by immunofluorescence and immunoelectron microscopy. Two monoclonal antibodies (MAb) utilized were against uPAR: MAb R4, which reacts with occupied and unoccupied uPAR, was concentrated at focal adhesions; MAb R3 reacting with unoccupied receptor stained cell surfaces diffusely. MAb R4 stained cell-cell contacts, tips of microspikes, and co-localized with vinculin. Of the matrix and integrin components tested, alpha v beta 3 integrin was found at focal adhesions but more centrally than uPAR. Since uPAR is anchored to the plasma membrane through a GPI lipid, we studied its mobility by antibody-induced clustering. This revealed that unoccupied uPAR was relatively mobile; MAb R3 redistributed it to clusters. In contrast, uPAR R4 and uPA antibodies at the focal contact sites remained mostly within focal contacts. Addition of exogenous uPA resulted in loss of R3 staining and increase of uPA in focal adhesions. These results suggest that occupancy of the receptor with uPA is associated with localization to cell contact sites and restricted lateral mobility.
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Pollo, Claudio, François Vingerhoets, Etienne Pralong, Joseph Ghika, Philippe Maeder, Reto Meuli, Jean-Philippe Thiran y Jean-Guy Villemure. "Localization of electrodes in the subthalamic nucleus on magnetic resonance imaging". Journal of Neurosurgery 106, n.º 1 (enero de 2007): 36–44. http://dx.doi.org/10.3171/jns.2007.106.1.36.
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Object The authors describe a new method of localizing electrodes on magnetic resonance (MR) images and focus on the positions of both the most efficient contact and the electrode related to the MR imaging target. Methods Thirty-one patients who had undergone bilateral subthalamic nucleus (STN) deep brain stimulation (DBS) were included in this study. Target coordinates were calculated in the anterior commissure–posterior commissure referential. A study of the correlation between the artifact and the related contact allowed one to deduce the contact position from the identification of the distal artifact on MR imaging. The best stimulation point corresponded with the contact resulting in the best Unified Parkinson’s Disease Rating Scale (UPDRS) motor score improvement. It was compared (Student t-test) with the dorsal margin of the STN (DM STN), which was determined electrophysiologically. The distance between the target and the electrode was calculated individually in each axis. The best stimulation point was located at anteroposterior −2.34 ± 1.63 mm, lateral 12.04 ± 1.62 mm, and vertical −2.57 ± 1.68 mm. This point was not significantly different from the DM STN (p < 0.05). The postoperative UPDRS motor score was 28.07 ± 12.16, as opposed to the preoperative score of 46.27 ± 13.89. The distance between the expected and actual target in the x- and y-axes was 1.34 ± 1.02 and 1.03 ± 0.76 mm, respectively. In the z-axis, 39.7% of the distal contacts were located proximal to the target. Conclusions This approach proposed for the localization of the electrodes on MR imaging shows that DBS is most effective in the dorsal and lateral part of the STN and indicates that the DBS electrode can be located more proximally than originally expected because of the caudal brain shift that may occur during the implantation procedure.
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LaPlant, F., E. J. Hutchinson y D. Ben-Amotz. "Raman Measurements of Localized Pressure Variations in Lubricants Above the Glass Transition Pressure". Journal of Tribology 119, n.º 4 (1 de octubre de 1997): 817–22. http://dx.doi.org/10.1115/1.2833891.
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Spatial pressure variations in synthetic lubricants contained in a static high-pressure diamond anvil cell (DAC), as well as in a loaded model bearing contact device, have been measured using the frequency shift of the lubricant’s Raman vibrational modes. Long-lived pressure fluctuations of ±0.5 GPa, with a relaxation time of several days, are observed m the static high pressure systems at an average pressure of 2.5 GPa. Evidence for rapidly varying pressure fluctuations in a concentrated contact is inferred from the increase in lubricant Raman linewidths. These results raise questions about key assumptions made in modeling EHD contacts. It is suggested that the present results are closely linked to recent observations of shear localization made by Winer and Bair.
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Wang, Yiping, Yanfeng Yang, Si Li, Zichen Su, Jinjie Guo, Penghu Wei, Jinguo Huang, Guixia Kang y Guoguang Zhao. "Automatic Localization of Seizure Onset Zone Based on Multi-Epileptogenic Biomarkers Analysis of Single-Contact from Interictal SEEG". Bioengineering 9, n.º 12 (5 de diciembre de 2022): 769. http://dx.doi.org/10.3390/bioengineering9120769.
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Successful surgery on drug-resistant epilepsy patients (DRE) needs precise localization of the seizure onset zone (SOZ). Previous studies analyzing this issue still face limitations, such as inadequate analysis of features, low sensitivity and limited generality. Our study proposed an innovative and effective SOZ localization method based on multiple epileptogenic biomarkers (spike and HFOs), and analysis of single-contact (MEBM-SC) to address the above problems. We extracted contacts epileptic features from signal distributions and signal energy based on machine learning and end-to-end deep learning. Among them, a normalized pathological ripple rate was designed to reduce the disturbance of physiological ripple and enhance the performance of SOZ localization. Then, a feature selection algorithm based on Shapley value and hypothetical testing (ShapHT+) was used to limit interference from irrelevant features. Moreover, an attention mechanism and a focal loss algorithm were used on the classifier to learn significant features and overcome the unbalance of SOZ/nSOZ contacts. Finally, we provided an SOZ prediction and visualization on magnetic resonance imaging (MRI). Ten patients with DRE were selected to verify our method. The experiment performed cross-validation and revealed that MEBM-SC obtains higher sensitivity. Additionally, the spike has better sensitivity while HFOs have better specificity, and the combination of these biomarkers can achieve the best performance. The study confirmed that MEBM-SC can increase the sensitivity and accuracy of SOZ localization and help clinicians to perform a precise and reliable preoperative evaluation based on interictal SEEG.
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Briesewitz, R., A. Kern, L. B. Smilenov, F. S. David y E. E. Marcantonio. "The membrane-cytoplasm interface of integrin alpha subunits is critical for receptor latency." Molecular Biology of the Cell 7, n.º 10 (octubre de 1996): 1499–509. http://dx.doi.org/10.1091/mbc.7.10.1499.
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Localization of integrin receptors to focal contact sites occurs upon ligand binding. This activity is latent, since unoccupied integrin receptors do not localize to focal contacts. Deletion analysis has revealed that the alpha cytoplasmic domains is required for the maintenance of integrin receptor latency. Our current hypothesis for the mechanism of integrin post-ligand binding events is that there is a change in relationship of alpha and beta cytoplasmic domains, which overcomes receptor latency. One possible mechanism for such a change would involve the amino acid residues at the membrane-cytoplasm interface. To test this hypothesis, we have produced point mutations in the human integrin alpha 1 subunit. These mutations had no effect on the adhesion via alpha 1 beta 1 to its ligand, collagen IV. However, receptor latency is lost in one of these mutants, leading to constitutive focal contact localization. This effect did not occur in receptors with an exchange of intracellular domains, suggesting that the mechanism of loss of latency involves a relative motion of the integrin chains. These results suggest a model in which post-ligand binding events in integrin receptors are associated with changes in the position of the alpha and beta cytoplasmic domains.
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SUEHIRO, Takashi y Katsushi IKEUCHI. "Fine Localization Based on Face Contact Constraints." Journal of the Robotics Society of Japan 11, n.º 4 (1993): 541–49. http://dx.doi.org/10.7210/jrsj.11.541.
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Xu, Wei, Qingying Ren, Jinze Li, Jie Xu, Gang Bai, Chen Zhu y Wei Li. "Triboelectric Contact Localization Electronics: A Systematic Review". Sensors 24, n.º 2 (11 de enero de 2024): 449. http://dx.doi.org/10.3390/s24020449.
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The growing demand from the extended reality and wearable electronics market has led to an increased focus on the development of flexible human-machine interfaces (HMI). These interfaces require efficient user input acquisition modules that can realize touch operation, handwriting input, and motion sensing functions. In this paper, we present a systematic review of triboelectric-based contact localization electronics (TCLE) which play a crucial role in enabling the lightweight and long-endurance designs of flexible HMI. We begin by summarizing the mainstream working principles utilized in the design of TCLE, highlighting their respective strengths and weaknesses. Additionally, we discuss the implementation methods of TCLE in realizing advanced functions such as sliding motion detection, handwriting trajectory detection, and artificial intelligence-based user recognition. Furthermore, we review recent works on the applications of TCLE in HMI devices, which provide valuable insights for guiding the design of application scene-specified TCLE devices. Overall, this review aims to contribute to the advancement and understanding of TCLE, facilitating the development of next-generation HMI for various applications.
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Afif, Afif Mohammad. "128 The Importance of Somatotopy to Achieve Clinical Benefit in Motor Cortex Stimulation for Pain Relief". Neurosurgery 64, CN_suppl_1 (24 de agosto de 2017): 229. http://dx.doi.org/10.1093/neuros/nyx417.128.
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Abstract INTRODUCTION The aim of this study was to search the relationship between the anatomical location and the eventual analgesic effect of each contact. METHODS 22 patients (14 men and 8 women) suffering from central and/or peripheral neuropathic pain were implanted with stimulation of the precentral cortex. The implantation of the electrodes was performed using intraoperative: 1) Anatomical identification by Neuronavigation with 3D MRI, 2) Somesthetic evoqued potentials monitoring to check the potential reverse over the central sulcus, 3) Electrical stimulations through the dura to identify the motor responses and its somatotopy. In order to locate postoperatively the electrodes, a 3D-CT was performed in each case and fused with the preoperative MRI. The clinical analgesic effects of cortical stimulation were collected on a regular basis (VAS reduction > 50%, drugs consumption). Data were analyzed to search a correlation between the anatomical position of contacts and analgesic effects. RESULTS >Post implantation analgesic effects were obtained in 18 (81.81%) patients out of 22. The analgesic effect was companied with reduction of the drugs consumption in 15 patients (68.18%). The post-operative 3D CT analysis shows a correspondence between the effective contacts localization and the motor cerebral cortex somatotopy in the patients with post-operative good analgesic effects. No correspondence was found between the contacts localization and the motor cerebral cortex somatotopy in the 4 patients with no analgesic effects. In three out of these four patients, analgesic effects were obtained after a new surgery allowing a replacement of the electrode position over the motor cortex somatotopy corresponding to the painful area. CONCLUSION This study shows the correlation between position of the contact over the precentral cortex and the analgesia obtained when the somatotopy of the stimulated cortex correspond to the painful area.
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Proshina, Z. G. "Contact Linguistics: Current Challenges and Perspectives". Moscow University Bulletin. Series 19. Linguistics and Intercultural Communication, Issue №4_2022 (31 de diciembre de 2022): 73–88. http://dx.doi.org/10.55959/msu-2074-1588-19-2022-4-73-88.
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The article discusses the terms sociolinguistics — contact linguistics — World Englishes paradigm. The structure of Contact Linguistics, whose central part is made by the World Englishes paradigm, is dwelt upon. Major problems of language contacts are overviewed, including differentiation of the global language, its localization and development of varieties. Varieties of a pluricentric language are defined as typified speech that is specific of a certain linguacultural social community, that reflects the mentality, cultural features and to a certain degree transfer of the native language. The author emphasizes that each variety is underpinned by a linguacultural identity of its users. Attention is focused on the legitimacy of the Expanding Circle varieties (according to B. Kachru) such as Russian and Chinese Englishes, need in their studying in theory and applied aspects.
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Senarath, W. A. T. N., S. A. W. Fernando y R. M. T. P. Rajakaruna. "Contact Position Estimation in the Event of Simultaneous Multiple Contacts in Vision-based Tactile Sensors". Journal of Advances in Engineering and Technology 2, n.º 1 (30 de septiembre de 2022): 52–64. http://dx.doi.org/10.54389/hhzm8357.
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Tactile sensors are used to detect physical contact or pressure. They provide feedback about the physical environment and allow more natural and intuitive interaction with machines. Tactile sensors have many applications in the fields of agriculture, space exploration, health and automotive. Capacitive, resistive, as well as vision (optical) based tactile sensors have been proposed in the literature. This paper proposes a novel approach to solving the problem of estimating the contact locations in the event of simultaneous multiple contacts in vision-based tactile sensors. The relationship between the contact force and the resulting physical deformation of the sensor material of a large-scale tactile sensor was studied with the aid of a custom-built hardware unit. Hardware architecture consists of a custom-designed flat rectangular sensor surface coupled with a mono-vision camera to capture the surface deformation. This method can capture detailed information on the resulting deformation for multiple simultaneous contacts. A software -based deformation estimation algorithm is proposed, where the grid array of marker positions was estimated with a tracking algorithm, an estimation algorithm, and a graphical representation algorithm. Moreover, separate analyses have been carried out to find the best suitable method to observe the deformation of the sensor material. In this study, the approach that was taken to find the contact position and deformation, produced results with an accuracy of more than 97%. Consequently, these results show that this method outperforms existing state-of-the-art techniques in terms of accuracy in the detection of the contact position. KEYWORDS: Vision-based tactile sensors, Surface deformation, marker-based localization, Contact point estimation
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Nikolaev, A. I., A. N. Ginali, A. V. Permyakova y V. R. Shashmurina. "Reference map of localization of contact points and contact areas of posterior teeth". Medical alphabet, n.º 24 (26 de septiembre de 2021): 34–38. http://dx.doi.org/10.33667/2078-5631-2021-24-34-38.
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The aim of the study: to find correlations in age-related characteristics of the localization and shape of the contact points in permanent posterior teeth and to develop a reference card for dentists, reflecting the age-related characteristics of the localization, shape and size of the contact areas of the posterior teeth in adults.Materials and research methods. The linear dimensions, area, shape, vertical and horizontal position in the interdental space of 1224 contact points of the posterior teeth in 236 patients aged 20 to 59 years was assessed based on a comprehensive analysis of intraoral radiographs performed using the bitewing technique, the results of the study of contact points using floss, displaying contact points on dental impressions made using a special technique.Research results. It was found that the interdental spaces of the posterior teeth in adult patients are characterized by the following features: the contact areas of the teeth are displaced in the vestibular direction, the buccal and lingual (palatal) interdental embrasures are asymmetric; dynamics of the depth of occlusal interdental embrasures, linear dimensions and area of contact areas is expressed as average digital values for different age groups: 20-40 years: contact areas – 1×2 mm, S = 2 mm2, depth of occlusal interdental embrasure - 1.5 mm ; over 40 years old: contact pads – 1.5×3 mm, S = 4.5 mm2, the depth of the occlusal interdental embrasure – 1.0 mm.Conclusion. On the basis of the data obtained, a «Reference map of the localization of contact points and contact areas of posterior teeth in adult patients» was proposed, which allows a dentist to obtain data on the features of the topography of the contact areas of the posterior teeth, taking into account the patient’s age during planning and performing interproximal caries treatment.
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Stieglitz, Lennart Henning, Christian Ayer, Kaspar Schindler, Markus Florian Oertel, Roland Wiest y Claudio Pollo. "Improved Localization of Implanted Subdural Electrode Contacts on Magnetic Resonance Imaging With an Elastic Image Fusion Algorithm in an Invasive Electroencephalography Recording". Operative Neurosurgery 10, n.º 4 (23 de junio de 2014): 506–13. http://dx.doi.org/10.1227/neu.0000000000000473.
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Abstract BACKGROUND: Accurate projection of implanted subdural electrode contacts in presurgical evaluation of pharmacoresistant epilepsy cases by invasive electroencephalography is highly relevant. Linear fusion of computed tomography and magnetic resonance images may display the contacts in the wrong position as a result of brain shift effects. OBJECTIVE: A retrospective study in 5 patients with pharmacoresistant epilepsy was performed to evaluate whether an elastic image fusion algorithm can provide a more accurate projection of the electrode contacts on the preimplantation magnetic resonance images compared with linear fusion. METHODS: An automated elastic image fusion algorithm (AEF), a guided elastic image fusion algorithm (GEF), and a standard linear fusion algorithm were used on preoperative magnetic resonance images and postimplantation computed tomography scans. Vertical correction of virtual contact positions, total virtual contact shift, corrections of midline shift, and brain shifts caused by pneumocephalus were measured. RESULTS: Both AEF and GEF worked well with all 5 cases. An average midline shift of 1.7 mm (SD, 1.25 mm) was corrected to 0.4 mm (SD, 0.8 mm) after AEF and to 0.0 mm (SD, 0 mm) after GEF. Median virtual distances between contacts and cortical surface were corrected by a significant amount, from 2.3 mm after linear fusion algorithm to 0.0 mm after AEF and GEF (P < .001). Mean total relative corrections of 3.1 mm (SD, 1.85 mm) after AEF and 3.0 mm (SD, 1.77 mm) after GEF were achieved. The tested version of GEF did not achieve a satisfying virtual correction of pneumocephalus. CONCLUSION: The technique provided a clear improvement in fusion of preimplantation and postimplantation scans, although the accuracy is difficult to evaluate.
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Mueller, S. C., Y. Yeh y W. T. Chen. "Tyrosine phosphorylation of membrane proteins mediates cellular invasion by transformed cells." Journal of Cell Biology 119, n.º 5 (1 de diciembre de 1992): 1309–25. http://dx.doi.org/10.1083/jcb.119.5.1309.
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Tyrosine phosphorylation of membrane-associated proteins is involved at two distinct sites of contact between cells and the extracellular matrix: adhesion plaques (cell adhesion and de-adhesion) and invadopodia (invasion into the extracellular matrix). Adhesion plaques from chicken embryonic fibroblasts or from cells transformed by Rous sarcoma virus contain low levels of tyrosine-phosphorylated proteins (YPPs) which were below the level of detection in 0.5-microns thin, frozen sections. In contrast, intense localization of YPPs was observed at invadopodia of transformed cells at sites of degradation and invasion into the fibronectin-coated gelatin substratum, but not in membrane extensions free of contact with the extracellular matrix. Local extracellular matrix degradation and formation of invadopodia were blocked by genistein, an inhibitor of tyrosine-specific kinases, but cells remained attached to the substratum and retained their free-membrane extensions. Invadopodia reduced or lost YPP labeling after treatment of the cells with genistein, but adhesion plaques retained YPP labeling. The plasma membrane contact fractions of normal and transformed cells have been isolated form cells grown on gelatin cross-linked substratum using a novel fractionation scheme, and analyzed by immunoblotting. Four major YPPs (150, 130, 81, and 77 kD) characterize invadopodial membranes in contact with the matrix, and are probably responsible for the intense YPP labeling associated with invadopodia extending into sites of matrix degradation. YPP150 may be an invadopodal-specific YPP since it is approximately 3.6-fold enriched in the invasive contact fraction relative to the cell body fraction and is not observed in normal contacts. YPP130 is enriched in transformed cell contacts but may also be present in normal contacts. The two major YPPs of normal contacts (130 and 71 kD) are much lower in abundance than the major tyrosine-phosphorylated bands associated with invadopodial membranes, and likely represent major adhesion plaque YPPs. YPP150, paxillin, and tensin appear to be enriched in the cell contact fractions containing adhesion plaques and invadopodia relative to the cell body fraction, but are also present in the soluble supernate fraction. However, vinculin, talin, and alpha-actinin that are localized at invadopodia, are equally concentrated in cell bodies and cell contacts as is the membrane-adhesion receptor beta 1 integrin. Thus, tyrosine phosphorylation of the membrane-bound proteins may contribute to the cytoskeletal and plasma membrane events leading to the formation and function of invadopodia that contact and proteolytically degrade the extracellular matrix; we have identified several candidate YPPs that may participate in the regulation of these processes.