A nanoplex PCR assay for the rapid detection of vancomycin and bifunctional aminoglycoside resistance genes in Enterococcus species

<p>Abstract</p> <p>Background</p> <p>Enterococci have emerged as a significant cause of nosocomial infections in many parts of the world over the last decade. The most common enterococci strains present in clinical isolates are <it>E. faecalis </it>and <it>E. faecium </it>which have acquired resistant to either gentamicin or vancomycin. The conventional culture test takes 2–5 days to yield complete information of the organism and its antibiotic sensitivity pattern. Hence our present study was focused on developing a nanoplex PCR assay for the rapid detection of vancomycin and bifunctional aminoglycoside resistant enterococci (V-BiA-RE). This assay simultaneously detects 8 genes namely 16S rRNA of <it>Enterococcus </it>genus, <it>ddl </it>of <it>E. faecalis </it>and <it>E. faecium</it>, <it>aac</it>A-<it>aph</it>D that encodes high level gentamicin resistance (HLGR), multilevel vancomycin resistant genotypes such as <it>van</it>A, <it>van</it>B, <it>van</it>C and <it>van</it>D and one internal control gene.</p> <p>Results</p> <p>Unique and specific primer pairs were designed to amplify the 8 genes. The specificity of the primers was confirmed by DNA sequencing of the nanoplex PCR products and BLAST analysis. The sensitivity and specificity of V-BiA-RE nanoplex PCR assay was evaluated against the conventional culture method. The analytical sensitivity of the assay was found to be 1 ng at the DNA level while the analytical specificity was evaluated with 43 reference enterococci and non-enterococcal strains and was found to be 100%. The diagnostic accuracy was determined using 159 clinical specimens, which showed that 97% of the clinical isolates belonged to <it>E. faecalis</it>, of which 26% showed the HLGR genotype, but none were vancomycin resistant. The presence of an internal control in the V-BiA-RE nanoplex PCR assay helped us to rule out false negative cases.</p> <p>Conclusion</p> <p>The nanoplex PCR assay is robust and can give results within 4 hours about the 8 genes that are essential for the identification of the most common <it>Enterococcus </it>spp. and their antibiotic sensitivity pattern. The PCR assay developed in this study can be used as an effective surveillance tool to study the prevalence of enterococci and their antibiotic resistance pattern in hospitals and farm animals.</p

Nickel hydroxide/chemical vapor deposition-grown graphene/nickel hydroxide/nickel foam hybrid electrode for high performance supercapacitors

Rational design of electrode structures has been recognized as an effective strategy to improve the electrochemical performance of electrode materials. Herein, we demonstrate an integrated electrode in which nickel hydroxide (Ni(OH)2) nanosheets are deposited on both sides of chemical vapor deposition-grown graphene on Ni foam, which not only effectively optimizes electrical conductivity of Ni(OH)2, but also accommodates the structural deformation assciated with the large volume change upon cycling. The synthesized Ni(OH)2/graphene/Ni(OH)2/Ni foam electrode exhibits a high specific capacity of 991 C g−1 at a current density of 1 A g−1, which is higher than the theoretical specific capacity of additive sum of Ni(OH)2 and graphene, and retains 95.4% of the initial capacity after 5000 cycles. A hybrid supercapacitor is constructed by using Ni(OH)2/graphene/Ni(OH)2/Ni foam as the positive electrode and activated carbon on Ni foam as the negative electrode, which achieves a maximum energy density of 49.5 W h kg−1 at a power density of 750 W kg−1, and excellent cycling lifespans with 89.3% retention after 10000 cycles at 10 A g−1

Structural behaviour of post-installed reinforcement bars in moment connections of wall-slabs

Post-installed reinforcement (PIR) bars helps to facilitate retrofitting works, mitigate misplaced reinforcement problems, as well as support newly casted additions. However, the use of PIR has not been addressed in the major reinforced concrete (RC) design codes worldwide. Recently, the European standards have introduced a beneficial coefficient of moments in EN 1992-4 2018 for concrete fastenings which allows compliant PIR systems to be designed by using the bonded anchor (BA) design method. However, when applying this method to wall-slab connection design, the moment resisting capacity is often limited by the lack of bar spacing and small concrete covers. This means that the method neglects long embedment depths and the connections designed based on this method are prone to brittle failure. In this paper, the strut and tie model (STM), which can better describe PIR with long embedment depths, together with the fundamental reinforced concrete (RC) theory is used to improve the ductility of moment connections with PIR bars. An experimental study is conducted to explore the structural behaviour of applying PIR bars that connect the wall and slab. Validations on the proposed STM and supplement to the BA design methods are made. From the experimental findings, measures are then proposed to enhance the ductility of the moment connections

A Note on Optimal Portfolio Selection and Diversification Benefits with a Short Sale Restriction on Real Estate Assets

This paper develops an optimal portfolio selection technique when short sales on real estate assets are restricted. Using the well-known mean-variance efficient concept, we are able to derive the optimal weights for portfolios consisting of both financial assets and real estate assets. Our paper provides a simple but powerful tool for portfolio managers to correctly construct mean-variance portfolios under short sale constraints.

Synthesis and Control of High Resolution Facial Expressions for Visual Interactions

The synthesis of facial expression with control of intensity and personal styles is important in intelligent and affective human-computer interaction, especially in face-to-face inter-action between human and intelligent agent. We present a facial expression animation system that facilitates control of expressiveness and style. We learn a decomposable genera-tive model for the nonlinear deformation of facial expressions by analyzing the mapping space between low dimensional embedded representation and high resolution tracking data. Bilinear analysis of the mapping space provides a compact representation of the nonlinear generative model for facial expressions. The decomposition allows synthesis of new fa-cial expressions by control of geometry and expression style. The generative model provides control of expressiveness pre-serving nonlinear deformation in the expressions with simple parameters and allows synthesis of stylized facial geometry. In addition, we can directly extract the MPEG-4 Facial Ani-mation Parameters (FAPs) from the synthesized data, which allows using any animation engine that supports FAPs to ani-mate new synthesized expressions. 1

Dynamic Correlation between Intrahost HIV-1 Quasispecies Evolution and Disease Progression

Quantifying the dynamics of intrahost HIV-1 sequence evolution is one means of uncovering information about the interaction between HIV-1 and the host immune system. In the chronic phase of infection, common dynamics of sequence divergence and diversity have been reported. We developed an HIV-1 sequence evolution model that simulated the effects of mutation and fitness of sequence variants. The amount of evolution was described by the distance from the founder strain, and fitness was described by the number of offspring a parent sequence produces. Analysis of the model suggested that the previously observed saturation of divergence and decrease of diversity in later stages of infection can be explained by a decrease in the proportion of offspring that are mutants as the distance from the founder strain increases rather than due to an increase of viral fitness. The prediction of the model was examined by performing phylogenetic analysis to estimate the change in the rate of evolution during infection. In agreement with our modeling, in 13 out of 15 patients (followed for 3–12 years) we found that the rate of intrahost HIV-1 evolution was not constant but rather slowed down at a rate correlated with the rate of CD4+ T-cell decline. The correlation between the dynamics of the evolutionary rate and the rate of CD4+ T-cell decline, coupled with our HIV-1 sequence evolution model, explains previously conflicting observations of the relationships between the rate of HIV-1 quasispecies evolution and disease progression

Sensor Fabrication Method for in Situ Temperature and Humidity Monitoring of Light Emitting Diodes

In this work micro temperature and humidity sensors are fabricated to measure the junction temperature and humidity of light emitting diodes (LED). The junction temperature is frequently measured using thermal resistance measurement technology. The weakness of this method is that the timing of data capture is not regulated by any standard. This investigation develops a device that can stably and continually measure temperature and humidity. The device is light-weight and can monitor junction temperature and humidity in real time. Using micro-electro-mechanical systems (MEMS), this study minimizes the size of the micro temperature and humidity sensors, which are constructed on a stainless steel foil substrate (40 μm-thick SS-304). The micro temperature and humidity sensors can be fixed between the LED chip and frame. The sensitivities of the micro temperature and humidity sensors are 0.06 ± 0.005 (Ω/°C) and 0.033 pF/%RH, respectively

Is Further Treatment Necessary for Patellar Crepitus After Total Knee Arthroplasty?

Introduction: Posterior-stabilized (PS) TKA that sacrifice the cruciate ligaments improves pain and function in patients with advanced osteoarthritis. Patellar crepitus appears to be due to a spectrum of peripatellar fibrosynovial formations and is usually encountered after PS-TKA, which uniquely has an intercondylar box to accept the tibial post. Symptoms of patellar crepitus occur most commonly during terminal knee extension and occur usually from 3 to 9 months after PS-TKA, and in some cases, this phenomenon is symptomatic enough to warrant an arthroscopic procedure or open arthrotomy. The development of patellar crepitus after PS-TKA appears related to many factors such as femoral component design, surgical errors, increased postoperative knee flexion, and postoperative patellar baja, which are also responsible for patellar clunk syndrome