Correction: Impact of visual impairment on balance and visual processing functions in students with special educational needs.

[This corrects the article DOI: 10.1371/journal.pone.0249052.].

Specific Amino Acid Substitutions in OXA-51-Type ß-Lactamase Enhance Catalytic Activity to a Level Comparable to Carbapenemase OXA-23 and OXA-24/40.

The chromosomal blaOXA-51-type gene encodes carbapenem-hydrolyzing class D ß-lactamases (CHDLs), specific variants shown to mediate carbapenem resistance in the Gram-negative bacterial pathogen Acinetobacter baumannii. This study aims to characterize the effect of key amino acid substitutions in OXA-51 variants of carbapenem-hydrolyzing class D ß-lactamases (CHDLs) on substrate catalysis. Mutational and structural analyses indicated that each of the L167V, W222G, or I129L substitutions contributed to an increase in catalytic activity. The I129L mutation exhibited the most substantial effect. The combination of W222G and I129L substitutions exhibited an extremely strong catalytic enhancement effect in OXA-66, resulting in higher activity than OXA-23 and OXA-24/40 against carbapenems. These findings suggested that specific arrangement of residues in these three important positions in the intrinsic OXA-51 type of enzyme can generate variants that are even more active than known CHDLs. Likewise, mutation leading to the W222M change also causes a significant increase in the catalytic activity of OXA-51. blaOXA-51 gene in A. baumannii may likely continue to evolve, generating mutant genes that encode carbapenemase with extremely strong catalytic activity.

Impact of visual impairment on balance and visual processing functions in students with special educational needs.

INTRODUCTION: Vision is critical for children's development. However, prevalence of visual impairment (VI) is high in students with special educational needs (SEN). Other than VI, SEN students are prone to having functional deficits. Whether visual problems relate to these functional deficits is unclear. This study aimed to assess the impact of vision on visual processing functions and balance in SEN students through a community service. METHODS: Visual acuity (VA) and contrast sensitivity were measured in a total of 104 (aged 14.3±4.3) SEN students as the visual outcomes, followed by retinoscopy. Visual processing function assessment included facial expression recognition by card matching examiner's facial expression matching, and visual orientation recognition. Dynamic balance, by Timed Up and Go test, and static standing balance (postural sway in double-legged standing with feet-together and tandem-stance for open-eye and closed-eye conditions) were assessed. Static balance was presented in terms of the maximal medial-lateral and antero-posterior sways. RESULTS: Of the 104 students, 62 (59.6%) were classified as visually impaired according to WHO classification of visual impairment based on presenting distance acuity. Ocular problems (e.g. optic nerve anomaly, uncorrected/ under-corrected refractive errors) and neurological anomalies were the major causes of vision loss. VA was positively associated with visual processing functions (all p ≤ 0.01), as SEN students with better vision tended to perform better in visual orientation and facial expression recognition tasks, as well as dynamic balance function (p = 0.04). For the static balance, postural sway and VA showed a positive relationship under open-eye and tandem stance conditions. However, the relationship between postural sway and VA became negative under closed-eye and tandem stance conditions. CONCLUSION: This study found a high prevalence of SEN students with visual impairment, in which many of them were undetected. Optometric examination is important to improve their visual function to minimize the effect of vision on functional performance. Vision is critical in visual processing as well as playing an important role in maintaining balance in SEN students.

Fixation stability and deviation in optical coherence tomography angiography using soft contact lens correction in myopes.

To compare fixation deviation and stability with soft contact lens correction and device built-in auto-focus system during optical coherence tomography angiography (OCTA). This observational study measured OCTA metrics first with contact lens correction, followed by removal of contact lenses, using the device auto-focus system at a University Optometry Clinic, Hong Kong. All participants were habitual soft contact lens wearers with either low or high myopia. OCTA measurements were obtained using a spectral domain OCTA. Fixation deviation was distance (in pixels) of the fovea to the center of the OCTA measurement grid. Fixation stability was test-retest repeatability (TRR) and coefficient of variation (CV) of fixation deviation from three consecutive OCTA measurements. OCTA metrics included vessel length density (VD), perfusion density (PD), and foveal avascular zone (FAZ) area. Averaged OCTA metrics were calculated from three measurements and compared between the two correction methods. The mean ± SD spherical equivalent of 74 eyes from 74 myopes measured was - 1.94D ± 0.75D in low myopes (n = 37) and - 7.97D ± 1.31D in high myopes (n = 37). When corrected with contact lenses, visual acuities of high myopes (median [IQR], - 0.06 [0.08] logMAR) and low myopes (- 0.02 ± 0.08 logMAR) were similar (P = 0.060), and with similar fixation deviation (5.0 ± 2.2 pixels vs 5.3 [3.6] pixels; P = 0.689). High myopes had poorer fixation stability than low myopes (TRR: 10.2 pixels vs 7.5 pixels; CV: 65% vs 54%, respectively). The worst fixation stability occurred when high myopes were corrected using the auto-focus system (TRR: 12.5 pixels, CV: 72%). The difference in VD and PD was within 1 mm-1 and 1%, respectively. The FAZ area was similar. Difference in OCTA metrics was small in each refractive group (< 1 mm-1 in VD, and < 2% in PD). High myopes had more stable fixation when corrected when wearing contact lenses. Subjects with good contact lens corrected visual acuity should wear their contact lenses during OCTA measurements.

Comparison of Choroidal Thickness Measurements Using Semiautomated and Manual Segmentation Methods.

SIGNIFICANCE: This study demonstrated that a semiautomated segmentation method could help inexperienced practitioners to obtain choroidal thickness as good as experienced practitioners. PURPOSE: The purpose of this study was to compare choroidal thickness measurements obtained by semiautomated and manual segmentation methods. METHODS: Optical coherence tomography images of 37 eyes from 37 healthy young subjects acquired by a spectral-domain optical coherence tomography device were reviewed retrospectively. Two naive examiners measured choroidal thickness using manual and semiautomated methods, whereas two experienced examiners used only the semiautomated method. The semiautomated method referred to a fully automated segmentation program customized based on MATLAB and followed manual verification. After highlighting the inner and outer choroidal boundaries through automated segmentation, examiners reviewed these boundaries in each B-scan and conducted manual revisions if segmentation errors occurred. After selecting points where correct boundary was located, the software used a spline fit to blend the corrected region with the rest of the boundary. All measurements were summarized in a 6-mm Early Treatment Diabetic Retinopathy Study grid. Operation time spent to complete retinal and choroidal segmentation on each eye was recorded. Between-examiner agreements, that is, intraclass correlation coefficient and coefficient of reproducibility (CoR), were calculated among four sets of semiautomated measurements, and within-examiner agreements were comparisons between manual and semiautomated results from the same naive examiners. Eyes with thin or thick choroids were also analyzed separately. RESULTS: The between-examiner and within-examiner agreements were excellent with intraclass correlation coefficient of 0.976 or greater. Pairwise within-examiner CoRs ranged from 17.4 to 47.1 µm. Pairwise between-examiner CoRs were between 13.0 and 38.9 µm. Eyes with thin choroid had better agreements than those with thick choroids. On average, naive examiners saved 3 to 5 minutes per eye using the semiautomated method. CONCLUSIONS: With the help of a dedicated software, inexperienced practitioners could obtain choroidal thickness measurements with accuracy similar to experienced practitioners. Processing time with the semiautomated method was also reduced.

Factors influencing inbound medical travel to India.

PURPOSE: The purpose of this paper is to explore the demand-side factors that influence the inbound medical tourists' (MTs) decision to travel abroad for medical treatment/surgery. DESIGN/METHODOLOGY/APPROACH: The researchers conducted thematic analysis of in-depth interviews in India with 24 foreign MTs' to generate the themes, identify factors and propose a model with hypothesis for future quantitative survey. FINDINGS: The findings conclude that patients ranked in ascending order less waiting time for surgery, healthcare quality and accreditation, staff/surgeons expertise, healthcare information, hospital facilities and services, patient safety, travel risk, surgical costs and holiday opportunity as important factors that influence the decision to travel abroad for medical treatment/surgery. RESEARCH LIMITATIONS/IMPLICATIONS: Foreign patients from six private hospitals were willing to be interviewed with the permission of the hospital. Due to confidentiality and privacy policy, many hospitals declined interviews with foreign patients. PRACTICAL IMPLICATIONS: The findings are generalised in case of foreign patients as MTs and all private hospitals treating foreign patients in India and other global healthcare destinations. Policy implications suggest that private hospitals in developing countries need to provide first-class quality of healthcare as foreign patients look for internationally accredited quality, no waiting time, patient safety, qualified and experienced surgeons, healthcare workers education and experience hospital facilities and post-surgery care with positive healthcare outcomes. ORIGINALITY/VALUE: There is little empirical research on the views of inbound MTs, about factors influencing their decision to travel abroad for surgery to India.

Triboluminescence of Centrosymmetric Lanthanide ß-Diketonate Complexes with Aggregation-Induced Emission.

Triboluminescence (TL) is a form of light emission induced upon mechanical forces on the material. However, our understanding of this phenomenon is still unclear and more examples are therefore needed in order to elucidate its mechanism. In this work, two types of TL complexes, [Eu(pp-dbm-Cl2)3phen] and [Eu(mm-dbm-Cl2)3phen], which also displays aggregation-induced emission (AIE) were synthesized and investigated for its photo-physical and crystal structural properties. These complexes were crystallized in a centro-symmetric space group P21/n, and remarkably, displayed TL upon grinding that may be due to the presence of extensive π···π, C-H···π and C-H···Cl-C interactions in the close molecular packing of its structure. This rare example deviates from the widely accepted mechanism of TL, hence widening the scope of our understanding in the area.

Assembly of Lanthanide(III) Cubanes and Dimers with Single-Molecule Magnetism and Photoluminescence.

Discrete lanthanide(III) tetranuclear cubane-like clusters seldom occur throughout the LnIII series and behave as single-molecule magnets (SMMs). Herein, a series of cubanes, [Ln4(µ3-OH)4(µ-tfa)4(hfa)4(phen)4] (1-9, Ln = La-Dy (except Pm), tfa = trifluoroacetate, hfa = hexafluoroacetylacetonate, phen = 1,10-phenanthroline), and dinuclear clusters, [Ln2(µ-OH)2(hfa)4(phen)2] (10-16, Ln = Tb-Lu), were synthesized and characterized. Two types of clusters were formed due to the change of preferred coordination geometry for lighter and heavier LnIII ions which favor nine-coordinated cubanes and eight-coordinated dimers, respectively. A magnetic study shows that 8-Tb4 and 9-Dy4 are ferromagnetically coupled and SMM in nature because of the larger Ln···Ln distance compared to other discrete cubanes. The anisotropic barriers, Ueff, of 9-Dy4 are determined to be 67.0 K. In addition, the photophysical properties of 6-Eu4, 8-Tb4, and 10-Tb2 owing to tfa, hfa, and phen sensitization and O-H quenching are discussed.

Using the Medial and Lateral Humeral Lines as an Adjunct to Intraoperative Elbow Arthrography to Guide Intraoperative Reduction and Fixation of Distal Humerus Physeal Separations Reduces the Incidence of Postoperative Cubitus Varus.

BACKGROUND: Distal humerus physeal separations are rare pediatric elbow fractures that are often misdiagnosed and difficult to treat. Adequate reduction is often technically challenging and up to 71% of children develop postoperative cubitus varus. We propose using the medial and lateral humeral lines as an adjunct to elbow arthrography in order to guide intraoperative fixation of distal humerus physeal separations to reduce the incidence of postoperative cubitus varus. METHODS: From 2009 to 2014, all pediatric patients under the age of 3 diagnosed with a distal humerus physeal separation and treated surgically at our institution were included for analysis. Two senior pediatric orthopaedic surgeons separately reviewed the preoperative, intraoperative, and postoperative images of all patients and measured the position of the ulnar axis relative to the medial and lateral humeral lines. The medial and lateral humeral shafts were defined as parallel lines drawn along the medial and lateral humeral diaphysis. Adequate reduction was defined by reduction of the ulnar axis within the boundaries of the medial and lateral humeral lines. Patients were assessed at latest follow-up for cubitus varus and any other surgical complications. RESULTS: Thirteen patients fulfilled the inclusion criteria and were on average 1.70 years old, ranging from 0.62 to 3 years old. Intraoperatively and immediately postoperatively, all 13 patients (100%) were noted to have adequate reduction of the ulnar axis within the boundaries medial and lateral humeral lines. None of the patients required intraoperative arthrography (0%). At the date of latest follow-up, 12 patients (92.3%) had no angular deformities compared with the contralateral limb and 1 patient (7.7%) had developed cubitus varus. No surgical complications were noted (0%). CONCLUSION: Intraoperative reduction of the ulnar axis within the boundaries of the medial and lateral humeral lines is associated with a lower incidence of postoperative cubitus varus in the treatment of distal humerus physeal separations in children. LEVEL OF EVIDENCE: Level IV.

Chiral transcription in self-assembled tetrahedral Eu4L6 chiral cages displaying sizable circularly polarized luminescence.

Predictable stereoselective formation of supramolecular assembly is generally believed to be an important but complicated process. Here, we show that point chirality of a ligand decisively influences its supramolecular assembly behavior. We designed three closely related chiral ligands with different point chiralities, and observe their self-assembly into europium (Eu) tetrametallic tetrahedral cages. One ligand exhibits a highly diastereoselective assembly into homochiral (either ΔΔΔΔ or ΛΛΛΛ) Eu tetrahedral cages whereas the two other ligands, with two different approaches of loosened point chirality, lead to a significant breakdown of the diastereoselectivity to generate a mixture of (ΔΔΔΔ and ΛΛΛΛ) isomers. The cages are highly emissive (luminescence quantum yields of 16(1) to 18(1)%) and exhibit impressive circularly polarized luminescence properties (|g lum|: up to 0.16). With in-depth studies, we present an example that correlates the nonlinear enhancement of the chiroptical response to the nonlinearity dependence on point chirality.

Mechanistic Investigation of Inducing Triboluminescence in Lanthanide(III) ß-Diketonate Complexes.

In this work, we synthesized a series of lanthanide(III) ß-diketonate complexes to investigate the induction of triboluminescence. Triboluminescence (TL) spectra, solid-state emission spectra, and luminescence lifetimes of the complexes were obtained to prove consistent emitting species for steady-state and triboluminescence measurements. Detailed analyses of the crystal lattice packing were conducted in an attempt to correlate crystal symmetry, gas discharge, and structural arrangements with "triboexcitation", and it is found that either noncentrosymmetric or centrosymmetic compounds can be TL-active. Furthermore, an intensely TL compound, Eu(dbm)4TMP, was achieved, and its light emission can be seen under daylight upon mechanical stress.

Reactivity of Hydrated Monovalent First Row Transition Metal Ions [M(H2O)n](+), M = Cr, Mn, Fe, Co, Ni, Cu, and Zn, n < 50, Toward Acetonitrile.

Reactions of [M(H2O)n](+), M = Cr, Mn, Fe, Co, Ni, Cu, and Zn, n < 50, with CH3CN are studied in the gas phase by Fourier transform ion cyclotron resonance (FT-ICR) mass spectrometry. Sequential uptake of 4-6 acetonitrile molecules is observed for all metals. Rate constants show a weak dependence on both the metal and the number of acetonitrile molecules already in the cluster. Nanocalorimetry yields the enthalpy of the first reaction step. For most metals, this is consistent with a ligand exchange of water against acetonitrile. For M = Cr, however, the strong exothermicity of ΔE(nc) = -195 ± 26 kJ mol(-1) suggests an electron transfer from Cr(+) to CH3CN. Exclusively for M = Zn, a relatively slow oxidation of the metal center to Zn(2+), with formation of ZnOH(+) and release of CH3CNH(•) or CH3CHN(•) is observed. Density functional theory molecular dynamics simulations and geometry optimizations show that charge transfer from Zn(+) to CH3CN as well as the subsequent proton transfer are associated with a barrier.

A method to generate recombinant Salmonella typhi Ty21a strains expressing multiple heterologous genes using an improved recombineering strategy.

Live attenuated Salmonella enterica serovar Typhi Ty21a (Ty21a) is an important vaccine strain used in clinical studies for typhoid fever and as a vaccine vector for the expression of heterologous antigens. To facilitate the use of Ty21a in such studies, it is desirable to develop improved strategies that enable the stable chromosomal integration and expression of multiple heterologous antigens. The phage λ Red homologous recombination system has previously been used in various gram-negative bacteria species to mediate the accurate replacement of regions of chromosomal DNA with PCR-generated 'targeting cassettes' that contain flanking regions of shared homologous DNA sequence. However, the efficiency of λ Red-mediated recombineering in Ty21a is far lower than in Escherichia coli and other Salmonella typhimurium strains. Here, we describe an improved strategy for recombineering-based methods in Ty21a. Our reliable and efficient method involves the use of linear DNA-targeting cassettes that contain relatively long flanking 'arms' of sequence (ca. 1,000 bp) homologous to the chromosomal target. This enables multiple gene-targeting procedures to be performed on a single Ty21a chromosome in a straightforward, sequential manner. Using this strategy, we inserted three different influenza antigen expression cassettes as well as a green fluorescent protein gene reporter into four different loci on the Ty21a chromosome, with high efficiency and accuracy. Fluorescent microscopy and Western blotting analysis confirmed that strong inducible expression of all four heterologous genes could be achieved. In summary, we have developed an efficient, robust, and versatile method that may be used to construct recombinant Ty21a antigen-expressing strains.