Search

Background The Centers for Disease Control and Prevention 2016 Healthcare-Associated Infections (HAI) Progress Report documented no change in catheter-associated urinary tract infections (CAUTIs) between 2009 and 2014. There is a need for investment in additional efforts to reduce HAIs, specifically CAUTI. Quality improvement fellowships are 1 approach to expand the capacity of dedicated leaders and infection prevention champions. Methods The fellowship used a model that expanded collaboration among disciplines and focused on partnership by recruiting a diverse cohort of fellows and by providing 1-on-1 mentoring to enhance leadership development. The curriculum supported the Association for Professionals in Infection Control and Prevention Competency Model in 2 domains: leadership and performance improvement and implementation science. Results The fellowship was successful. The fellows and mentors had self-reported high level of satisfaction, fellows' knowledge increased, and they demonstrated leadership, quality improvement, and implementation science competency within the completed capstone projects. Conclusions A model encompassing diverse educational topics, discussions, workshops, and mentorship can serve as a template for developing infection prevention champions. Although this project focused on CAUTI, this template can be used in a variety of settings and applied to a range of other HAIs and performance improvement projects.

Objectives. To assess the prevalences across Europe of radiological indices of degenerative inter-vertebral disc disease (DDD); and to quantify their associations with, age, sex, physical anthropometry, areal BMD (aBMD) and change in aBMD with time. Methods. In the population-based European Prospective Osteoporosis Study, 27 age-stratified samples of men and women from across the continent aged 50+ years had standardized lateral radiographs of the lumbar and thoracic spine to evaluate the severity of DDD, using the Kellgren-Lawrence (KL) scale. Measurements of anterior, mid-body and posterior vertebral heights on all assessed vertebrae from T4 to L4 were used to generate indices of end-plate curvature. Results. Images from 10 132 participants (56% female, mean age 63.9 years) passed quality checks. Overall, 47% of men and women had DDD grade 3 or more in the lumbar spine and 36% in both thoracic and lumbar spine. Risk ratios for DDD grades 3 and 4, adjusted for age and anthropometric determinants, varied across a three-fold range between centres, yet prevalences were highly correlated in men and women. DDD was associated with flattened, non-ovoid inter-vertebral disc spaces. KL grade 4 and loss of inter-vertebral disc space were associated with higher spine aBMD. Conclusion. KL grades 3 and 4 are often used clinically to categorize radiological DDD. Highly variable European prevalences of radiologically defined DDD grades 3+ along with the large effects of age may have growing and geographically unequal health and economic impacts as the population ages. These data encourage further studies of potential genetic and environmental causes. © The Author 2017. Published by Oxford University Press on behalf of the British Society for Rheumatology. All rights reserved.

This paper describes a new casting system for transtibial socket fabrication. Like the earlier CIR Sand Casting System, the CIR Casting System is based on the 'dilatancy' principle that is similar to the packaging process for coffee beans by which loose beans become a solid mass when a vacuum is applied. The main difference from the CIR Sand Casting System is that the CIR Casting System uses light-weight, polystyrene beads in place of silica sand as the primary material for casting the negative mold. The formed negative mold can be converted into a positive sand model for modification and socket formation. With the new plaster-less casting system, the prosthetist can fabricate a transtibial prosthesis in about one hour. It reduces the set-up cost, overall weight and size of the casting system, and increases portability for service in remote areas. The System also creates minimal waste and is energy-conserving and environmentally-friendly.

The Center for International Rehabilitation (CIR) developed a wheelchair provision strategy that combines central fabrication with regional distribution and local service provision by trained practitioners. A field study was initiated in Kabul, Afghanistan to evaluate this plan.The CIR-Whirlwind Wheelchair (study wheelchair) is an adult size, manual wheelchair designed to be adjustable to accommodate the individual user and durable to withstand rugged terrain. Manufactured in India, the study wheelchairs, with seat cushions, were packaged as kits and shipped to Afghanistan. Local practitioners in Kabul were trained on user assessment, fitting and training, and wheelchair assembly, maintenance and repair. One hundred subjects with previous experience of independently propelling a manual wheelchair participated in the study. This 4-month study entailed three subject visits for initial wheelchair fitting and training and then follow-up at 3 and 10 weeks. Subject training included wheelchair use and maintenance, and wheelchair skill activities.The study wheelchair was rated favorably by the subjects in all of five categories. Adjustments made to the wheelchairs during the study were typical for maintaining or improving the fit or function of a manual wheelchair. With the exception of brake handles, the need to repair or replace components on the wheelchairs was minimal. The subjects' proficiency at wheelchair skill activities increased throughout the study.Data collected indicates that the study wheelchair performed very well. The data also served to identify those aspects of the wheelchair that may require additional development and testing prior to further production. To gain additional information on long term wheelchair use and performance, the CIR plans to extend this study by interviewing the same subjects at nine and fifteen months from the date they originally received the study wheelchair.

High k-dielectrics have become an important material in the development of ultra shallow junctions. In addition, strontium titanium oxide (STO) has been used as an interposer material to grow GaAs on Si for MESFETs [RF devices implemented on GaAs on Si substrates using a SrTiO3 buffer layer, Motorola knowledge base, 14 September 2001]. Also, SrTiO3 has a potential to be used as insulating material between ferromagnetic electrodes in magnetic tunnel junctions for magnetic random access memory devices (M-RAM). In this study we have investigated a multilayer system of STO with lanthanum barium manganese oxide (LBMO). The layer thickness was down to 0.8 nm, corresponding to two unit cells of SrTiO3. With low energy Cs bombardment a depth resolution down to 2 nm per decade and a peak width of 2 nm FWHM was achieved. Since the erosion rates of STO and LBMO differ greatly, we will discuss a depth calibration procedure based on actual material composition.

Epitaxy of oxide materials on silicon (Si) substrates is of great interest for future functional devices using the large variety of physical properties of the oxides as ferroelectricity, ferromagnetism, or superconductivity. Recently, materials with high spin polarization of the charge carriers have become interesting for semiconductor-oxide hybrid devices in spin electronics. Here, we report on pulsed laser deposition of magnetite (Fe3O4) on Si(001) substrates cleaned by an in situ laser beam high temperature treatment. After depositing a double buffer layer of titanium nitride (TiN) and magnesium oxide (MgO), a high quality epitaxial magnetite layer can be grown as verified by RHEED intensity oscillations and high resolution x-ray diffraction., Comment: submitted

Demineralized bone has had limited use as a medical implant, although, recently Jackson et al. (Am J Sports Med 1996;24(4):405-414) examined using demineralized bone as an anterior cruciate ligament (ACL) replacement and found that within 1 year the demineralized bone had remodeled from a haversian system (bone-like) into a ligament-like structure. Little research has been done to characterize the mechanical properties of demineralized bone and examine its potential as a ligament replacement. This research examined the mechanical properties of demineralized bone as a function of acid saturation time and methods of processing and sterilization using specimens from various anatomic locations. Bone specimens were manufactured from the tibia, metatarsus, femur, radius, and humerus of bovine bone. Tensile strength, strain, and modulus of elasticity were examined for various acid saturation times and sterilization treatments. Additionally, viscoelastic properties, creep and stress relaxation, and fatigue properties were examined. The findings indicate that completely demineralized bone has mechanical properties similar to the ACL and, therefore, has increased likelihood for success in ACL reconstruction surgery.

Running is a very popular sport with millions of participants worldwide. As with any physical activity, injuries occur when the musculoskeletal system is overloaded. Running surfaces are often cited as a cause of injuries. The objective of this work was to determine changes in ground contact times, impulses, and shoe reaction forces while running on different surfaces. Eleven healthy adult males (22.9 ± 3.2 years, 176.9 ± 8.4 cm, 74.5 ± 8.6 kg) were recruited to run on four different surfaces: asphalt, concrete, grass, and a synthetic track. The majority of research on running surfaces has been completed in laboratory settings with force plates mounted beneath the running surfaces. Plantar pressure technology permits data collection on the actual running surfaces outside the laboratory. Therefore, data were collected at 250 Hz using a Parotec® plantar pressure measurement system. Participants ran at the same velocity on each of the surfaces. No significant differences were detected among the surfaces for shoe reaction forces, contact time, or impulse (P > 0.05). This implies that runners who choose to run on stiffer surfaces are not exposing themselves to additional risk as a result of loading but possibly because of internal compensatory mechanisms. However, these results may not apply to all runners.

We report on the fabrication and structural characterization of coherently strained La 2/3 Ca 1/3 MnO 3 (LCMO) thin films and La 2/3 Ca 1/3 MnO 3 /La 2/3 Ba 1/3 MnO 3 (LCMO/LBMO) heterostructures on SrTiO 3 substrates. The thin films grow in a layer-by-layer mode as verified by reflection high energy electron diffraction (RHEED) and atomic force microscopy (AFM). X-ray diffraction (XRD) reciprocal space mapping shows that the thin films match the substrate lattice constants leading to a strong tetragonal distortion of the lattice. Such (ultra)thin films and heterostructures are well suited for a systematic investigation of the influence of biaxial strain on the physical properties of doped manganites.

By pulsed-laser deposition epitaxial thin films of ${\mathrm{Sr}}_{2}{\mathrm{FeMoO}}_{6}$ have been prepared on (100) ${\mathrm{SrTiO}}_{3}$ substrates. Already for a deposition temperature of 320 \ifmmode^\circ\else\textdegree\fi{}C epitaxial growth is achieved. Depending on deposition parameters the films show metallic or semiconducting behavior. At high (low) deposition temperature the FeMo sublattice has a rock-salt (random) structure. The metallic samples have a large negative magnetoresistance which peaks at the Curie temperature. The magnetic moment was determined to $4{\ensuremath{\mu}}_{B}$ per formula unit (f.u.), in agreement with the expected value for an ideal ferrimagnetic arrangement. We found at 300 K an ordinary Hall coefficient of $\ensuremath{-}6.01\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}10} {\mathrm{m}}^{3}/\mathrm{As},$ corresponding to an electronlike charge-carrier density of 1.3 per FeMo pair. In the semiconducting films the magnetic moment is reduced to $1{\ensuremath{\mu}}_{B}/\mathrm{f}.\mathrm{u}.$ due to disorder in the FeMo sublattice. In low fields an anomalous holelike contribution dominates the Hall voltage, which nearly vanishes at low temperatures for the metallic films only.

Despite the activities of many orthotic and prosthetic provision organizations in resource-limited environments, there is still a great need and there are several areas for improvement, as identified in Part One of this series.Our goal was to examine outcomes and conclusions of research studies to produce an evidence base for determining factors that may lead to successful provision of orthoses and prostheses in resource-limited environments.Literature review.We conducted a scoping literature review of all information related to orthotic and prosthetic provision in resource-limited environments published from 2000 to 2010. We extracted measured outcomes reported in all types of articles and analyzed conclusions from research studies.Reported outcomes included durability, cost, satisfaction, use/nonuse of device, amount of utilization, walking speed, discomfort, pain, fit, misalignment, capacity for service provision, number of devices produced or delivered, and number of graduates from training programs.There are many gaps in the evidence base, notably in measuring inclusion, participation, and quality of life for orthosis and prosthesis users in resource-limited environments. There is a paucity of reported outcomes for orthotics. Valid, reliable, and standard methods of data collection and reporting are needed to advance the field and enhance the evidence base.

Poster: "ECR 2013 / C-2203 / In vivo diffusion tensor imaging of the neonatal rat brain development" by: "M. Breu1, D. Reisinger2, D. Wu2, Y. Zhang2, K. Goeral2, A. Fatemi2, J. Zhang2; 1Wien/AT, 2Baltimore, MD/US"

Magnetite epitaxial thin films have been prepared by pulsed laser deposition on MgO and Si substrates. The magnetic and electrical properties of these epitaxial films are close to those of single crystals. For 40-50 nm thick films, the saturation magnetization and electrical conductivity are ∼450emu∕cm3 and 225Ω−1cm−1 at room temperature, respectively. The Verwey transition temperature is 117K. The Hall effect data yield an electron concentration corresponding to 0.22 electrons per formula unit at room temperature. Both normal and anomalous Hall effect have been found to have negative sign.

For the properties of devices based on oxide multilayers, interfaces play a crucial role. For ferromagnetic tunnel junctions the sign of the spin polarization depends on the barrier material and the interface termination. Here, we present a transmission electron microscopy study of heteroepitaxial trilayer systems consisting of a SrTiO3 insulating barrier sandwiched between La2/3D1/3MnO3 (D=Ca or Ba) electrodes grown on SrTiO3 substrates. Intermixing during growth depends on the earth alkaline ion: Ca segregates to the surface of the growing epitaxial thin film, leading to a Ca rich interface layer between the bottom electrode and the barrier. In contrast, no Ba segregation could be detected in the well lattice-matched Ba-doped film. In addition, a significant diffusion of both Ca and Ba into the SrTiO3 tunneling barrier is found, whereas the diffusion of Mn is negligibly small. Our results explain the different tunneling magnetoresistance in various manganite based tunnel junctions.

Epitaxial coherency strain is a crucial parameter strongly influencing the complex interplay between structure as well as spin, charge, and orbital degrees of freedom in the doped manganites. We have grown epitaxial manganite thin films on various substrates using ultrahigh vacuum laser molecular beam epitaxy with RHEED control. In order to study transport perpendicular to the film plane, mesa structures have been fabricated into the epitaxial films. For coherently strained La2/3Ca1/3MnO3 and La2/3Ba1/3MnO3 thin films grown on SrTiO3 and NdGaO3 substrates, an unusual transport anisotropy is observed. Whereas metallic behavior is found within the plane of biaxial coherency strain, for transport perpendicular to this plane an insulating behavior and nonlinear current–voltage characteristics are observed. This behavior can be interpreted in terms of a strain induced orbital order effect at fixed doping. Our results demonstrate the effect of epitaxial coherency strain in heterostructures required for magnetoe...

Literature ReviewWe estimate that over 29 million people worldwide in resource-limited environments (RLEs) are in need of orthotic and prosthetic (OP) devices and services.Our goal was to ascertain the current state of OP provision in RLEs and identify factors that may lead to more successful OP provision.We conducted a comprehensive scoping literature review of all information related to OP provision in RLEs published from 2000 to 2010. We targeted Vietnam, Cambodia, Tanzania, Malawi, Colombia, and the Navajo Nation, but also included information about developing countries in general. We searched academic databases and grey literature. We extracted information from each article in the areas of design, manufacturing, distribution, service provision, and technology transfer.We identified commonly reported considerations and strategies for OP provision from 431 articles. Analysis of expert consensus documents revealed recurring themes for improving OP provision. We found that some suggestions from the consensus documents are being followed, but many are overlooked or have not yet been implemented.Areas for improvement include conducting field testing during the design process, providing services to rural environments, offering follow-up services, considering government collaboration, and encouraging an active role of the orthosis/prosthesis user. Outcomes and research studies will be further discussed in Part Two.

We report on the preparation and characterization of the double-perovskite compound Sr2CrWO6 with a Curie temperature of 390 K. We have fabricated both Sr2CrWO6 bulk sintered polycrystalline bars and high-quality epitaxial thin films on SrTiO3 substrates by pulsed-laser deposition. The samples were characterized by thermogravimetric analysis, x-ray diffraction, electrical transport, and magnetization measurements. Polycrystalline samples containing a large number of grain boundaries show a large low-field magnetoresistance of up to 100% at 5 K. At room temperature, this effect is reduced to a few percent. Our results show that Sr2CrWO6 is an interesting candidate for room-temperature magnetoelectronic materials.

Transition metal oxides show fascinating physical properties such as high temperature superconductivity, ferro- and antiferromagnetism, ferroelectricity or even multiferroicity. The enormous progress in oxide thin film technology allows us to integrate these materials with semiconducting, normal conducting, dielectric or non-linear optical oxides in complex oxide heterostructures, providing the basis for novel multi-functional materials and various device applications. Here, we report on the combination of ferromagnetic, semiconducting, metallic, and dielectric materials properties in thin films and artificial heterostructures using laser molecular beam epitaxy. We discuss the fabrication and characterization of oxide-based ferromagnetic tunnel junctions, transition metal-doped semiconductors, intrinsic multiferroics, and artificial ferroelectric/ferromagetic heterostructures - the latter allow for the detailed study of strain effects, forming the basis of spin-mechanics. For characterization we use X-ray diffraction, SQUID magnetometry, magnetotransport measurements, and advanced methods of transmission electron microscopy with the goal to correlate macroscopic physical properties with the microstructure of the thin films and heterostructures., 21 pages, 21 figures (2 figures added, typos corrected)

The purpose of this study was to transfer three simplified alignment techniques to prosthetic technicians in a developing country through training materials and a hands-on training workshop, and to subsequently evaluate the efficacy of the alignment systems in producing acceptably aligned monolimb prostheses.Prosthetists utilized the anatomically-based-alignment (ABA)-standing, ABA-supine and vertical alignment axis (VAA) alignment systems to produce three monolimbs for each of 30 healthy and active transtibial amputees. Prosthetists assessed all three monolimbs for each subject in both static and gait conditions to determine which monolimb had the best alignment and produced the best functional gait. Subjects also selected the monolimb which they believed had the best alignment; subjects utilized each monolimb for a 1-month home assessment.Twenty-eight subjects completed the study. Eighty-four monolimbs were evaluated by the prosthetists and the subjects. A few monolimbs had minor socket fitting and alignment issues, but none prevented evaluation in the laboratory or during the 1-month home assessment. Only three monolimbs had poor alignment and could not be worn by the subjects.All three systems captured acceptable alignments, although the two systems that incorporate weight bearing, the ABA-standing and VAA alignment systems, produced slightly better outcomes. The alignment ratings between these two systems were statistically insignificant.

The purpose of this study was to evaluate three alignment systems based on two alignment theories that can be utilized in the fabrication of monolimb prostheses that have acceptable alignment. A second goal was to assess the feasibility of technology transfer for providing prosthetic services to remote areas of landmine-affected countries.Five prosthetists and five healthy transtibial amputees participated in the study. Each prosthetist was trained and then used each of the three systems to capture alignment measurements for one subject. Three monolimbs identified as X, Y and Z were fabricated for each subject and assessed during clinical static and dynamic gait conditions. Training materials and methods were also evaluated.All three systems captured acceptable alignments fairly well, although the two systems that incorporated weight-bearing into the alignment process had slightly better outcomes. Each system has its own advantages in terms of ease of use, required equipment, and ease of technology transfer.All three systems have the potential for application in outreach prosthetic services and warrant continued evaluation. Minor changes need to be incorporated into the alignment systems and procedures to make them easier to use and more effective.

This study examined force and repetition during simulated distance cycling with regard to how they may possibly influence the on-set of the overuse injury at the knee called iliotibial band friction syndrome (ITBFS). A 3D motion analysis system was used to track lower limb kinematics during cycling. Forces between the pedal and foot were collected using a pressure- instrumented insole that slipped into the shoe. Ten recreational athletes (30.6"5.5 years) with no known history of ITBFS participated in the study. Foot-pedal force, knee flexion angle and crank angle were examined as they relate to the causes of ITBFS. Specifically, foot-pedal force, repetition and impingement time were calculated and compared with the same during running. A minimum knee flexion angle of approximately 338 occurred at a crank angle of 1708. The foot-pedal force at this point was 231 N. This minimum knee flexion angle falls near the edge of the impingement zone of the iliotibial band (ITB) and the femoral epicondyle, and is the point at which ITBFS is aggravated causing pain at the knee. The foot-pedal forces during cycling are only 18% of those occurring during running while the ITB is in the impingement zone. Thus, repetition of the knee in the impingement zone during cycling appears to play a more prominent role than force in the on-set of ITBFS. The results also suggest that ITBFS may be further aggravated by improper seat position (seat too high), anatomical differences, and training errors while cycling. 2002 Elsevier Science B.V. All rights reserved.

The use of oxide materials in oxide electronics requires their controlled epitaxial growth. Recently, it was shown that Reflection High Energy Electron Diffraction (RHEED) allows to monitor the growth of oxide thin films even at high oxygen pressure. Here, we report the sub-unit cell molecular or block layer growth of the oxide materials Sr2RuO4, MgO, and magnetite using Pulsed Laser Deposition (PLD) from stoichiometric targets. Whereas for perovskites such as SrTiO3 or doped LaMnO3 a single RHEED intensity oscillation is found to correspond to the growth of a single unit cell, in materials where the unit cell is composed of several molecular layers or blocks with identical stoichiometry, a sub-unit cell molecular or block layer growth is established resulting in several RHEED intensity oscillations during the growth of a single unit-cell.

We report on the preparation and characterization of epitaxial thin films of the double-perovskite Sr$_2$CrWO$_6$ by Pulsed Laser Deposition (PLD). On substrates with low lattice mismatch like SrTiO$_3$, epitaxial Sr$_2$CrWO$_6$ films with high crystalline quality can be grown in a molecular layer-by-layer growth mode. Due to the similar ionic radii of Cr and W, these elements show no sublattice order. Nevertheless, the measured Curie temperature is well above 400 K. Due to the reducing growth atmosphere required for double perovskites, the SrTiO$_3$ substrate surface undergoes an insulator-metal transition impeding the separation of thin film and substrate electric transport properties., Comment: 3 pages, 5 figures

To be successful a bipedal locomotion system will be required to robustly traverse terrain with unknown and varying surface conditions. Even in made-for-human environments a broad range of surface conditions may be encountered and slipping is a very real and serious concern. Since a priori detection and avoidance is not practical, a robust system must detect and respond to the unexpected event after it has occurred and before control is lost. This must be accomplished in an extremely limited time frame. This paper proposes the use of human-like reflexes to enable robust recovery from slipping. The proposed algorithm seamlessly integrates reflexive responses into the nominal control system. Effectiveness of the algorithm is demonstrated via simulation results.

Robotic assist devices typically consist of a manipulator attached to a robot arm. Often, the assist device must perform the functions of the human hand. Therefore, they should have sufficient dexterity to manipulate an object without putting it down. Four fingered manipulators are by their very nature more complex than then three fingered counterparts. But, with the additional finger, the four fingered hands can manipulate an object without setting it down. We describe a novel design that introduces an additional degree of freedom to one finger, and the design optimization process that insures that the six fundamental grasps (spherical, cylindrical, tip, hook, palmar and lateral) are possible. In addition, we discuss how this one additional degree of freedom increases the manipulability of a three fingered manipulator so that a limited array of object manipulation is possible.

Restoring hand control to upper extremity paralysis victims will enable them the perform daily tasks and lead independent lifestyles. This study was undertaken to develop a fuzzy controlled hand orthosis that will be unobtrusive, user friendly and aesthetically pleasing. A simplified hand orthosis model, consisting of four fingers and a thumb, is derived for the purpose of planning appropriate grasp trajectories (fingertip pinch, lateral pinch and cylindrical grasp) and validating a fuzzy logic control architecture. The controller is hierarchical in design, consisting of a supervisory controller that uses the intended motion to coordinate individual finger motions and, a lower level controller for each finger that produces the required joint angles for the specific grasp. Preliminary results indicate that the hand orthosis model is capable of achieving the required grasps, and that fuzzy logic can be used as the controller.

Biaxially strain is an important parameter in the complex phase diagram of the doped manganites that can lead to a different groundstate compared to bulk single crystals at the same doping level. For coherently strained La 2/3 Ca 1/3 MnO 3 thin films on SrTiO 3 substrates, we report an unusual direction dependence of the electrical transport properties. For transport perpendicular to the substrate induced strained plane, an insulating behavior associated with non-linear current–voltage characteristics is observed. We propose an A-type antiferromagnetic groundstate for the biaxially strained films as is consistent with the observed strongly reduced saturation magnetization.

A bibliography is given which covers the time period from 1962 through 1989. This bibliography contains a listing of published literature on the broad subject of live-line maintenance and related topics. References appearing in archival publications are included. Although many articles on the subject also appeared in trade journals and nontechnical literature, these are not included in this bibliography for the sake of brevity. >

The functional capability of antigen-stimulated breast milk cells to produce an immunologic mediator was examined. Colostrum and comparison peripheral blood samples were obtained from ten women, two to four days postpartum, and supernatants from PPD-stimulated mononuclear cell cultures were assayed for the lymphokine, monocyte chemotactic factor. Five of the ten women studied had a history of a positive tuberculin skin test and one had received BCG immunization. Peripheral blood lymphocyte cultures and colostrum cell cultures from four of these six women produced monocyte chemotactic factor. These results demonstrated the functional capability of antigen-stimulated colostral cells to produce immunologic mediators.

Previous evaluation of lymphocytes taken from patients with Wiskott-Aldrich syndrome (WAS) and other X-linked immunodeficiencies has revealed deficiencies of a lymphocyte sialoglycoprotein with a relative molecular mass of 115 kD (designated gpL-115) found in normal lymphocytes. The development of monoclonal antibodies to gpL-115 has permitted the detection of molecular heterogeneity in gpL-115 from the lymphocytes of immunodeficient patients. When lymphocytes from normal individuals were analyzed by immunoblotting, gpL-115 with only a single molecular species (115 kD) was detected. Lymphocytes from 17 immunodeficient patients were analyzed after overnight incubation. Two patients had no gpL-115 with an Mr of 115 kD, but gpL-115 with an Mr of either 95 or 135 kD was detected. Nine patients had gpL-115 with Mr equally of 95 and 115 Kd. Other patients exhibited gpL-115 with combinations of 95, 115, and 135 kD. The heterogeneity of the degraded gpL-115 suggests that WAS and other X-linked immunodeficiencies are due to a series of abnormalities, all of which involve gpL-115, and may explain the clinical heterogeneity of the diseases.

While the interplay between actin filaments and actin crosslinking proteins has been extensively characterized in bulk studies, only very few experiments address this interaction on the level of single molecules. Hence, the longstanding question whether unfolding of crosslinking proteins is relevant to the mechanical response of the actin cytoskeleton remains to be elucidated.To this end, we developed a four-bead optical tweezers assay which allows probing individual actin-crosslinker-actin bonds. Two actin filaments decorated with crosslinking proteins are suspended crosswise between two trapped beads each, forming a double dumbbell geometry. A feedback control keeps formed bonds under constant force thus enabling us to measure the force dependence of lifetime distributions. As the probed filaments are freely suspended in solution, the presented experimental approach mimics the situation in actin networks very well.We used this assay to characterize the well-known actin crosslinking proteins α-Actinin und Filamin. Our results indicate that unfolding of these proteins in a physiological context seems very unlikely as the bond between filament and crosslinking protein ruptures first.

[This corrects the article DOI: 10.1371/journal.pone.0277347.]., (Copyright: © 2023 Reisinger et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.)