Divalent metal ion in the active site of purple acid phosphatase modulates substrate binding: Kinetic and thermodynamic properties.

The purple acid phosphatase was purified from 5.9-fold to apparent homogeneity from Anagelis arvensis seeds using SP-Sephadex C-50 and Sephadex G-100 chromatography. The results of residual activity tests conducted using different temperature ranges (50-70 °C) were calculated as the activation energy (Ed = 72 kJ/mol), enthalpy (69.31 ≤ (ΔH° ≤ 69.10 kJ/mol), entropy (-122.48 ≤ ΔS° ≤ -121.13 J/mol·K), and Gibbs free energy (108.87 ≤ ΔG° ≤ 111.25 kJ/mol) of the enzyme irreversible denaturation. These thermodynamic parameters indicate that this novel PAP is highly thermostable and may be significant for use in industrial applications. However, it may be confirmed by stopped-flow measurements that this substitution produces a chromophoric Fe3+ site and a Pi-substrate interaction that is about ten times faster. Additionally, these data show that phenyl phosphate hydrolysis proceeds more rapidly in metal form of A. arvensis PAP than the creation of a µ-1,3 phosphate complex. The Fe3+ site in the native Fe3+-Mn2+ derivative interacts with it at a faster rate than in the Fe3+-Fe2+ form. This is most likely caused by a network of hydrogen bonds between the first and second coordination spheres. This suggests that the choice of metal ions plays a significant role in regulating the activity of this enzyme.

Vertical growth of a 3D Ni-Co-LDH/N-doped graphene aerogel: a cost-effective and high-performance sulfur host for Li-S batteries.

Sulfur hosts and conversion catalysts based on NiCo-LDHs exhibit potential for improving the performance of Li-S batteries. Nevertheless, their low electron conductivity and aggregation propensity restrict their applicability. This investigation employs a temporary scaffold of ZIF-67 to produce a nanotube assembly of Ni-Co-LDH encapsulated within an N-doped graphene sponge. The electrochemically developed interface has an extended active surface area, and the clumping of LDH nanosheets is effectively inhibited by the design of the nanotube arrangement. Furthermore, the incorporation of nitrogen within the structure of graphene results in a boost of electrical conductivity and provides an increased quantity of active sites. Interfacial electron transport is facilitated by the interfacial rearrangement of charges resulting from p-n heterojunctions and fosters redox activity. In this study, the researchers have presented the double role played by the nickel-cobalt layered double hydroxide (NiCo-LDH) nanotubes in improving the polysulphide (LiPS) conversion and decreasing the movement of the sulphur (S) ions by forming surface-bound intermediates. The battery that was fabricated using the above composite cathode mixture showed a higher energy storage ability, i.e., 1190.0 mA h g-1 at J = 0.2. Furthermore, the battery showed a significantly higher capacity to rapidly supply energy and displayed a rate capacity of 670.1 mA h g-1 at J = 5C. Also, the above battery displayed a longer cycle life, with 1000 charge-discharge cycles and the deterioration rate of 0.029% for each cycle.

Cobalt oxide modified sulfur and phosphorus Co-doped g-C3N4 for screening of urinary human albumin.

The fabrication of a heteroatom-doped nanocomposite based on cobalt oxide modified sulfur, phosphorus co-doped carbon nitride (Co3O4/SP-CN) with increased active sites is reported. The synthesized nanocomposite offers surprisingly high electrocatalytic oxidation efficacy toward human albumin (HA) despite its agglomeration. This improved efficacy of Co3O4/SP-CN nanocomposite could be attributed to its increased adsorption sites and surface defects, fast charge transportation capability, and conductivity. Additionally, morphological and compositional analysis of the fabricated Co3O4/SP-CN material has been performed  through scanning electron microscopy (SEM), X-ray diffraction (XRD), X-ray photon spectroscopy (XPS), and Raman spectroscopy. The fabricated electrode shows remarkable amperometric response against the HA with a limit of detection of 8.39 nM and linear range of 20-4000 nM at applied potential of 0.25 V versus Ag/AgCl in 0.1 M PBS (pH 8.2). The designed Co3O4/SP-CN electrode has been successfully applied to monitor HA in  urine samples of diabetic patient with recovery percentage from 94.1 and 92.1% and with relative standard deviation (RSD) values of 5.8 and 7.8%. According to the best of our knowledge, this is the first report to use a Co3O4/SP-CN-based graphitic pencil (GP) electrode for monitoring of HA for early diagnosis of diabetic nephropathy.

The Avon patellofemoral joint arthroplasty: two- to 18-year results of a large single-centre cohort.

Aims: This study reports on the medium- to long-term implant survivorship and patient-reported outcomes for the Avon patellofemoral joint (PFJ) arthroplasty. Patients and Methods: A total of 558 Avon PFJ arthroplasties in 431 patients, with minimum two-year follow-up, were identified from a prospective database. Patient-reported outcomes and implant survivorship were analyzed, with follow-up of up to 18 years. Results: Outcomes were recorded for 483 implants (368 patients), representing an 86% follow-up rate. The median postoperative Oxford Knee Score (0 to 48 scale) was 35 (interquartile range (IQR) 25.5 to 43) and the median Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC, 0 to 100 scale) was 35 (IQR 25 to 53) at two years. There were 105 revisions, 61 (58%) for progression of osteoarthritis. All documented revisions were to primary knee systems without augmentation. The implant survival rate was 77.3% (95% confidence interval (CI) 72.4 to 81.7, number at risk 204) at ten years and 67.4% (95% CI 72.4 to 81.7 number at risk 45) at 15 years. Regression analysis of explanatory data variable showed that cases performed in the last nine years had improved survival compared with the first nine years of the cohort, but the individual operating surgeon had the strongest effect on survivorship. Conclusion: Satisfactory long-term results can be obtained with the Avon PFJ arthroplasty, with maintenance of patient-reported outcome measures (PROMs), satisfactory survival, and low rates of loosening and wear. Cite this article: Bone Joint J 2018;100-B:1162-7.

Survivorship and clinical outcome of the minimally invasive Uniglide medial fixed bearing, all-polyethylene tibia, unicompartmental knee arthroplasty at a mean follow-up of 7.3years.

BACKGROUND: Medial UKA performed in England and Wales represents seven to 11% of all knee arthroplasty procedures, and is most commonly performed using mobile-bearing designs. Fixed bearing eliminates the risk of bearing dislocation, however some studies have shown higher revision rates for all-polyethylene tibial components compared to those that utilize metal-backed implants. The aim of the study is to analyse survivorship and maximum eight-year clinical outcome of medial fixed bearing, Uniglide unicompartmental knee arthroplasty performed using an all-polyethylene tibial component with a minimal invasive approach. METHODS: Between 2002 and 2009, 270 medial fixed UKAs were performed in our unit. Patients were reviewed pre-operatively, five and eight years post-operatively. Clinical and radiographic reviews were carried out. Patients' outcome scores (Oxford, WOMAC and American Knee Score) were documented in our database and analysed. RESULTS: Survival and clinical outcome data of 236 knees with a mean of 7.3years follow-up are reported. Every patient with less than 4.93years of follow-up underwent a revision. The patients' average age at the time of surgery was 69.5years. The American Knee Society Pain and Function scores, the Oxford Knee Score and the WOMAC score all improved significantly. The five-year survival rate was 94.1% with implant revision surgery as an end point. The estimated 10years of survival rate is 91.3%. Fourteen patients were revised before the five-year follow-up. CONCLUSION: Fixed bearing Uniglide UKA with an all-polyethylene tibial component is a valuable tool in the management of a medial compartment osteoarthritis, affording good short-term survivorship. Level of evidence IV.

Phakic intraocular lenses outcomes and complications: Artisan vs Visian ICL.

PURPOSE: To evaluate the safety and visual outcomes of two phakic intraocular lenses (IOLs) for correction of high myopia: Artisan and Visian ICL (ICL). PATIENTS AND METHODS: In this retrospective study, a phakic IOL was implanted in 68 highly myopic eyes of 34 patients; 42 eyes received an Artisan IOL, and 26 eyes received ICL IOL. RESULTS: All patients completed a 1-year follow-up. The mean preoperative spherical equivalent (SEQ) was -12.89 ± 3.78, and -12.44 ± 4.15 diopters (D) for Artisan and ICL (P=0.078), respectively. The mean postoperative (1-year) uncorrected distance visual acuity was 0.39 ± 0.13 and 0.41 ± 0.15 logMAR for Artisan and ICL, respectively (P=0.268). The mean postoperative (1-year) corrected distance visual acuity was 0.36 ± 0.12 and 0.31 ± 0.12 logMAR for Artisan and ICL, respectively (P=0.128). The mean postoperative SEQ was -0.86 ± 0.5 and -0.63 ± 0.38 D for Artisan and ICL, respectively (P=0.67). Intraocular pressure change at 1 year was 0.64 ± 2.7 and 1.88 ± 0.6 mm Hg for Artisan and ICL, respectively (P=0.77). CONCLUSION: Artisan and ICL showed equal and comparable safety, predictability, and efficacy.

Iatrogenic surface damage during femoral component impaction in total knee arthroplasty.

Application of prosthesis components during knee arthroplasty surgery involves impacting the femoral component using an impaction device and a heavy mallet. This could damage the component and may therefore be of concern to knee surgeons. Using a drop tower with a set-up that mimics the impaction generated clinically when a surgeon hits the femoral component, we investigated the possible surface damage to the femoral component. Three parameters were obtained and compared with a contact profilometer to characterize the roughness: R(a), R(pk) and R(z). The effect of the impacts on the contour of the femoral components was also investigated. After 3 series of impactions, no difference in surface roughness of the femoral component important enough to increase the wear rate could be detected neither for Cobalt Chrome or Oxidized Zirconium components. Our study therefore indicates that impacting the femoral component during TKA does not alter the component's surface roughness.

Does the joint line matter in revision total knee replacement?

We identified 148 patients who had undergone a revision total knee replacement using a single implant system between 1990 and 2000. Of these 18 patients had died, six had developed a peri-prosthetic fracture and ten had incomplete records or radiographs. This left 114 with prospectively-collected radiographs and Bristol knee scores available for study. The height of the joint line before and after revision total knee replacement was measured and classified as either restored to within 5 mm of the pre-operative height or elevated if it was positioned more than 5 mm above the pre-operative height. The joint line was elevated in 41 knees (36%) and restored in 73 (64%). Revision surgery significantly improved the mean Bristol knee score from 41.1 (SD 15.9) pre-operatively to 80.5 (SD 15) post-operatively (p < 0.001). At one year post-operatively both the total Bristol knee score and its functional component were significantly better in the restored group than in the elevated group (p < 0.01). Overall, revision from a unicondylar knee replacement required less use of bone graft, fewer component augments, restored the joint line more often and gave a significantly better total Bristol knee score (p < 0.02) and functional score (p < 0.01) than revision from total knee replacement. Our findings show that restoration of the joint line at revision total knee replacement gives a significantly better result than leaving it unrestored by more than 5 mm. We recommend the greater use of distal femoral augments to help to achieve this goal.

Observed kneeling ability after total, unicompartmental and patellofemoral knee arthroplasty: perception versus reality.

Kneeling is an important function of the knee, but little information is available on ability to kneel after different knee arthroplasty procedures. Previous work has asked patients about their kneeling ability; in this study it was objectively assessed. One hundred and twenty two patients - 38 having had total knee replacement (TKR), 53 unicompartmental knee replacement (UKR), 31 patello-femoral replacement (PFR) - were observed trying to kneel at 90 degrees on a chair, at 90 degrees on the floor, and at 120 degrees on the floor. Only 37% of patients thought they could kneel, whereas 81% were actually able to kneel ( p<0.001). Ability to kneel on the chair and on the floor at 90 degrees was significantly better than perceived ability for all prosthesis types ( p<0.001). Kneeling at 120 degrees showed no difference between perception and reality except for the PFR group ( p<0.05). In all positions, increased range of movement significantly improved kneeling ability ( p<0.001). Kneeling ability in men was significantly better than in women ( p<0.001). Patient-centred questionnaires do not accurately document kneeling ability after knee arthroplasty.

Can knees kneel? Kneeling ability after total, unicompartmental and patellofemoral knee arthroplasty.

This study investigates patients' perception of kneeling ability before and at 1 and 2 years after total, unicompartmental knee replacement (UKR) and patellofemoral knee replacement (PFR), for osteoarthritis. Kneeling is an important function of the knee joint required for many daily activities and inability to kneel after knee surgery is a frequent cause of dissatisfaction. Data were prospectively collected on 253 knees. A kneeling score was obtained by analysis of the relevant section of the Oxford knee score. Scores were obtained pre-operatively and at 1 and 2 years post-operatively. Absolute values and change following surgery were recorded. Correlations with pain and other knee functions were also made. Kneeling ability prior to surgery was poor in all 3 groups (80% found it extremely difficult or impossible to kneel) and improved in all groups after surgery (20% had little or no difficulty to kneel at 2 years). Kneeling ability was best in UKR and worst in PFR. These results suggest that kneeling ability in osteoarthritic patients is poor but improves with knee arthroplasty surgery, however the majority of patients will still have difficulty in kneeling.

Button versus buttonless castings for removable partial denture frameworks.

Casting removable partial dentures (RPDs) without completely filling the sprue channels and generating casting buttons would result in saving metal and making more defect-free castings. This investigation tested whether a complete and sound RPD casting can be obtained when a minimal amount of metal is used. A factorial experimental design, three spruing methods, two metal feeding directions, and two different weights of metal were used to cast 60 Kennedy class II, modification 1 RPDs. The metal used to cast each framework was either enough to result in a full button or in no button. Visual and radiographic examinations and counting of defects were made by two independent operators who were unaware of the spruing method, feeding direction, or amount of metal used to make the framework. The completeness of the casting and the presence of porosities were evaluated for clasps, major connectors, and meshworks. The use of minimal metal to cast RPDs was equally as successful as using enough for a full button, provided that the appropriate spruing arrangement and metal feeding direction were chosen. Indirect metal feeding for maxillary RPDs was successful with the proper spruing arrangement.