IS THE “U-SIGN” RADIOLOGIC FEATURE OF A POSTERIOR CRUCIATE LIGAMENT TIBIAL AVULSION FRACTURE?

ABSTRACT Objective: By analyzing our cases of posterior cruciate ligament (PCL) tibial avulsion fracture, we noted that a U-shaped image was present in the anteroposterior plain radiographs view of the affected knee, even in cases where the profile view of the knee had been inconclusive as to tibial PCL avulsion fracture, a “hidden” fracture. Therefore, we aimed to investigate whether there was an anatomical correlation between this radiological U sign and the tibial insertion of the PCL and to ascertain the intra- and inter-rater reliability of this sign in clinical practice. Methods: The data of the widths and heights area of the PCL tibial insertion area, and the U sign area were measured and compared to the largest width of the tibia. Two moreover, the reliability and reproducibility of this imaging were analyzed. Results: The areas height of the U-sign area and the anatomical insertion area of the posterior cruciate ligament showed no difference, and both were topographically located in the two central quarters of the proximal end of the tibia. The radiographic assessment showed excellent Kappa agreement rates between interobserver and intraobserver, with high reliability and reproducibility. Conclusion: The U sign is a radiographic feature of PCL tibial avulsion fracture seen on the radiograph AP view, there is a high association between the ratios of the U-sign area height in the X-ray and the anatomical height of the PCL tibial insertion site MRI with the largest width of the proximal tibia. The radiographic U sign showed excellent rates of interobserver and intraobserver agreement with Kappa values higher than 0.8. Level of Evidence IV; Dignostic Studies - Investigating a Diagnostic Test.

Generating biomembrane-like local curvature in polymersomes via dynamic polymer insertion

Biomembrane curvature formation has long been observed to be essential in the change of membrane morphology and intracellular processes. The significant importance of curvature formation has attracted scientists from different backgrounds to study it. Although magnificent progress has been achieved using liposome models, the instability of these models restrict further exploration. Here, we report a new approach to mimic biomembrane curvature formation using polymersomes as a model, and poly(N-isopropylacrylamide) to induce the local curvature based on its co-nonsolvency phenomenon. Curvatures form when poly(N-isopropylacrylamide) becomes hydrophobic and inserts into the membrane through solvent addition. The insertion area can be fine-tuned by adjusting the poly(N-isopropylacrylamide) concentration, accompanied by the formation of new polymersome-based non-axisymmetric shapes. Moreover, a systematic view of curvature formation is provided through investigation of the segregation, local distribution and dissociation of inserted poly(N-isopropylacrylamide). This strategy successfully mimicks biomembrane curvature formation in polymersomes and a detailed observation of the insertion can be beneficial for a further understanding of the curvature formation process. Furthermore, polymer insertion induced shape changing could open up new routes for the design of non-axisymmetric nanocarriers and nanomachines to enrich the boundless possibilities of nanotechnology.

Importance of the Application of Lean Manufacturing and Sustainable Manufacturing and Its Impact on Productivity and Quality in the Electronics Industry of Mexicali

An evaluation of use of lean and sustainable manufacturing tools was made, correlating them with the productivity and quality indices in an industry of the electronic sector located in the city of Mexicali. In this evaluated company, it was observed that some improper manufacturing methods was used and for this reason, generated a large amount of waste from electronic devices and electronic boards. This caused the productivity and quality indices to decrease, originating the need for extra time and with it unnecessary costs that devalued the prices of manufactured products, due to the competitiveness in the electronic industry sector evaluated. With the application of tools of lean manufacturing and sustainable manufacturing, the productivity and quality levels were increased and both overtime and unnecessary costs were reduced, achieving competitive prices in the evaluated industry. The installation method of electronic components with polarity in electronic boards was evaluated, due to the fact that a great diversity of products emerged from the automatic insertion area with defects, indicating reversed polarity, which should be solved, otherwise, short circuits could be generated or lack of electrical conductivity, in the manufactured products in their final process. This caused the manufactured products to not work properly, causing the presence of defective products and with it low levels of productivity and quality and economic losses. and It was detected that this occurred due to the lack of training of the operative personnel and the neglect of the operative workers of the automatic insertion area. In order to control this situation, as a methodological part, schematic models were developed to support the operational personnel in their activities in the automatic insertion area. This proposal with the schematic models developed for use in the electronics industry, where the research was made. The study was developed from 2018 to 2019.

Measuring Protein Insertion Areas in Lipid Monolayers by Fluorescence Correlation Spectroscopy

The insertion of protein domains into membranes is an important step in many membrane remodeling processes, for example in vesicular transport. The membrane area taken up by the protein insertion influences the protein binding affinity as well as the mechanical stress induced in the membrane and thereby its curvature. Total area changes in lipid monolayers can be measured on a Langmuir film balance. Finding the area per inserted protein however proves challenging for two reasons: The number of inserted proteins must be determined without disturbing the binding equilibrium and the change in the film area can be very small. Here we address both issues using Fluorescence Correlation Spectroscopy (FCS): Firstly, by labeling a fraction of the protein molecules fluorescently and performing FCS experiments directly on the monolayer, the number of inserted proteins is determined in situ without having to rely on invasive techniques, such as collecting the monolayer by aspiration. Secondly, by using another FCS color channel and adding a small fraction of fluorescent lipids, the reduction in fluorescent lipid density accompanying protein insertion can be monitored to determine the total area increase. Here, we use this method to determine the insertion area per molecule of Sar1, a protein of the COPII complex, which is involved in transport vesicle formation, in a lipid monolayer. Sar1 has an N-terminal amphipathic helix, which is responsible for membrane binding and curvature generation. An insertion area of (3.4 ± 0.8) nm2 was obtained for Sar1 in monolayers from a lipid mixture typically used in reconstitution, in good agreement with the expected insertion area of the Sar1 amphipathic helix. By using the two-color approach, determining insertion areas relies only on local fluorescence measurements. No macroscopic area measurements are needed, giving the method the potential to be applied also to laterally heterogeneous monolayers and bilayers.Statement of SignificanceWe show that two color Fluorescence Correlation Spectroscopy (FCS) measurements can be applied to the binding of a protein to a lipid monolayer on a Langmuir film balance in order to determine the protein insertion area. One labelling color was used to determine the number of bound proteins and the other one to monitor the area expansion of the lipid monolayer upon protein binding. A strategy for the FCS data analysis is provided, which includes focal area calibration by raster image correlation spectroscopy and a framework for applying z-scan FCS and including free protein in the aqueous subphase. This approach allows determining an area occupied by a protein in a quasi-planar model membrane from a local, non-invasive, optical measurement.

The Anatomical Numerical Measurement of Posterior Cruciate Ligament: A Vietnamese Cadaveric Study

BACKGROUND: The posterior cruciate ligament (PCL) is crucial to restrain the posterior translation of the tibia. Its anatomical structure is complex. A proper understanding of PCL anatomy may assist surgeon in reconstructing anatomically native PCL. AIM: To describe the anatomical numerical measurement of the PCL in Vietnamese adults. METHODS: Twenty-one fresh cadaveric knees were examined. The macroscopic details of the intra-articular PCL, the attachment of the anterolateral bundle (ALB), posteromedial bundles (PMB) to the femur and tibia were analysed. We used a digital camera to photograph the cadaveric specimens and used the ImageJ software to analyse the collected images. RESULTS: The ALB and PMB length were 35.5 ± 2.78 and 32.6 ± 2.28 mm, respectively. The smallest and the biggest diameter of middle third of the PCL were 5.9 ± 0.71 and 10.0 ± 1.39 mm, respectively. The area of cross section of middle third of the PCL was 53.6 ± 12.37 mm2. The femoral insertion area of ALB and PMB were 88.4 ± 16.89 and 43.5 ± 8.83 mm2, respectively. The distance from the central point of femoral ALB, PMB, and total PCL insertion to the Blumensaat line were 5.5 ± 0.91, 11.5 ± 1.98, and 7.6 ± 1.42 mm, respectively. The shortest distance from medial femoral cartilage rim to the central point of femoral ALB, PMB, and total PCL insertion were 7.0 ± 0.79, 7.3 ± 0.95, and 7.8 ± 1.73 mm, respectively. The tibial insertion area of ALB and PMB were 84.5 ± 12.52 and 47.8 ± 6.20 mm2 respectively. The shortest distance from the posterior cartilage corner of the medial tibial plateau to the central point of ALB, PMB, and total PCL insertion to tibia were 8.5 ± 1.02, 9.4 ± 1.11, and 8.3 ± 1.1 mm, respectively. The central point of tibial PCL insertion was 9.7±1.08 mm below cartilage plane of the medial tibial plateau. CONCLUSION: This study describes the detailed anatomical measurement of the PCL and its bundles in adults.

Polyurethane Transparent Dressing Protection on the Insertion Area of Peripheral Intra Venous Catheter (PIVC)

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Individualized Anterior Cruciate Ligament Graft Matching: In Vivo Comparison of Cross-sectional Areas of Hamstring, Patellar, and Quadriceps Tendon Grafts and ACL Insertion Area

Background: Recent literature correlated anterior cruciate ligament (ACL) reconstruction failure to smaller diameter of the harvested hamstring (HS) autograft. However, this approach may be a simplification, as relation of graft size to native ACL size is not typically assessed and oversized grafts may impart their own complications. Purpose: To evaluate in vivo data to determine if the commonly used autografts reliably restore native ACL size. Study Design: Descriptive laboratory study. Methods: Intraoperative data of the tibial insertion area and HS graft diameter were collected and retrospectively evaluated for 46 patients who underwent ACL reconstruction with HS autografts. Magnetic resonance imaging measurements of the cross-sectional area (CSA) of the possible patellar tendon (PT) and quadriceps tendon (QT) autografts were also done for each patient. The percentages of tibial insertion site area restored by the 3 possible grafts were then calculated and compared for each individual. Results: The mean ACL tibial insertion area was 107.2 mm2 (60.5-155.5 mm2). The mean CSAs of PT, HS, and QT were 33.2, 55.3, and 71.4 mm2, respectively. When all grafts were evaluated, the percentage reconstruction of the insertion area varied from 16.2% to 123.1% on the tibial site and from 25.5% to 176.7% on the femoral site, differing significantly for each graft type ( P < .05). On average, 32.8% of the tibial insertion area would have been filled with PT, 53.6% by HS, and 69.5% by QT. Based on previous cadaveric studies indicating that graft size goal should be 50.2% ± 15% of the tibial insertion area, 82.7% of patients in the HS group were within this range (36.9%, QT; 30.5%, PT), while 65.2% in the PT group were below it and 60.9% in the QT group were above it. Conclusion: ACL insertion size and the CSAs of 3 commonly used grafts vary greatly for each patient and are not correlated with one another. Thus, if the reconstructed ACL size is determined by the harvested autograft size alone, native ACL size may not be adequately restored. PT grafts tended to undersize the native ACL, while QT might oversize it. Clinical Relevance: These results may help surgeons in preoperative planning, as magnetic resonance imaging measurements can be helpful in determining individualized graft choice to adequately restore the native ACL.