Computer-assisted placement technique in hip resurfacing arthroplasty: improvement in accuracy?

Freehand positioning of the femoral drill guide is difficult during hip resurfacing and the surgeon is often unsure of the implant position achieved peroperatively. The purpose of this study was to find out whether, by using a navigation system, acetabular and femoral component positioning could be made easier and more precise. Eighteen patients operated on by the same surgeon were matched by sex, age, BMI, diagnosis and ASA score (nine patients with computer assistance, nine with the regular ancillary). Pre-operative planning was done on standard AP and axial radiographs with CT scan views for the computer-assisted operations. The final position of implants was evaluated by the same radiographs for all patients. The follow-up was at least 1year. No difference between both groups in terms of femoral component position was observed (p > 0.05). There was also no difference in femoral notching. A trend for a better cup position was observed for the navigated hips, especially for cup anteversion. There was no additional operating time for the navigated hips. Hip navigation for resurfacing surgery may allow improved visualisation and hip implant positioning, but its advantage probably will be more obvious with mini-incisions than with regular incision surger

Corrigendum: Investigating the Effect of Selected Non-Saccharomyces Species on Wine Ecosystem Function and Major Volatiles [Front. Bioeng. Biotechnol., 6, (2018) (169)] DOI: 10.3389/fbioe.2018.00169

In the original article, there was a mistake in Figure 2 as published. The order of the graphs (A-H) is incorrect and does not match the caption nor the in-text citation. The corrected Figure 2 appears below. The authors apologize for this error and state that this does not change the scientific conclusions of the article in any way. The original article has been updated

Enzyme stability in nanoparticle preparations part 1: Bovine serum albumin improves enzyme function

Enzymes have gained attention for their role in numerous disease states, calling for research for their efficient delivery. Loading enzymes into polymeric nanoparticles to improve biodistribution, stability, and targeting in vivo has led the field with promising results, but these enzymes still suffer from a degradation effect during the formulation process that leads to lower kinetics and specific activity leading to a loss of therapeutic potential. Stabilizers, such as bovine serum albumin (BSA), can be beneficial, but the knowledge and understanding of their interaction with enzymes are not fully elucidated. To this end, the interaction of BSA with a model enzyme B-Glu, part of the hydrolase class and linked to Gaucher disease, was analyzed. To quantify the natural interaction of beta-glucosidase (B-Glu,) and BSA in solution, isothermal titration calorimetry (ITC) analysis was performed. Afterwards, polymeric nanoparticles encapsulating these complexes were fully characterized, and the encapsulation efficiency, activity of the encapsulated enzyme, and release kinetics of the enzyme were compared. ITC results showed that a natural binding of 1:1 was seen between B-Glu and BSA. Complex concentrations did not affect nanoparticle characteristics which maintained a size between 250 and 350 nm, but increased loading capacity (from 6% to 30%), enzyme activity, and extended-release kinetics (from less than one day to six days) were observed for particles containing higher B-Glu:BSA ratios. These results highlight the importance of understanding enzyme:stabilizer interactions in various nanoparticle systems to improve not only enzyme activity but also biodistribution and release kinetics for improved therapeutic effects. These results will be critical to fully characterize and compare the effect of stabilizers, such as BSA with other, more relevant therapeutic enzymes for central nervous system (CNS) disease treatments

The Binding Pocket at the Interface of Multimeric Telomere G-quadruplexes: Myth or Reality?

Human telomeric DNA with hundreds of repeats of the 5’-TTAGGG-3’ motif plays a crucial role in several biological processes. It folds into G-quadruplex (G4) structures and features a pocket at the interface of two contiguous G4 blocks. Up to now no structural NMR and crystallographic data are available for ligands interacting with contiguous G4s. Naphthalene diimide monomers and dyads were investigated as ligands of a dimeric G4 of human telomeric DNA comparing the results with those of the model monomeric G4. Time-resolved fluorescence, circular dichroism, isothermal titration calorimetry and molecular modeling were used to elucidate binding features. Ligand fluorescence lifetime and induced circular dichroism unveiled occupancy of the binding site at the interface. Thermodynamic parameters confirmed the hypothesis as they remarkably change for the dyad complexes of the monomeric and dimeric telomeric G4. The bi-functional ligand structure of the dyads is a fundamental requisite for binding at the G4 interface as only the dyads engage in complexes with 1 : 1 stoichiometry, lodging in the pocket at the interface and establishing multiple interactions with the DNA skeleton. In the absence of NMR and crystallographic data, our study affords important proofs of binding at the interface pocket and clues on the role played by the ligand structure

Nickel and gtp modulate helicobacter pylori ureg structural flexibility

UreG is a P-loop GTP hydrolase involved in the maturation of nickel-containing urease, an essential enzyme found in plants, fungi, bacteria, and archaea. This protein couples the hydrolysis of GTP to the delivery of Ni(II) into the active site of apo-urease, interacting with other urease chaperones in a multi-protein complex necessary for enzyme activation. Whereas the conformation of Helicobacter pylori (Hp) UreG was solved by crystallography when it is in complex with two other chaperones, in solution the protein was found in a disordered and flexible form, defining it as an intrinsically disordered enzyme and indicating that the well-folded structure found in the crystal state does not fully reflect the behavior of the protein in solution. Here, isothermal titration calorimetry and site-directed spin labeling coupled to electron paramagnetic spectroscopy were successfully combined to investigate HpUreG structural dynamics in solution and the effect of Ni(II) and GTP on protein mobility. The results demonstrate that, although the protein maintains a flexible behavior in the metal and nucleotide bound forms, concomitant addition of Ni(II) and GTP exerts a structural change through the crosstalk of different protein regions

Meanfield treatment of Bragg scattering from a Bose-Einstein condensate

A unified semiclassical treatment of Bragg scattering from Bose-Einstein condensates is presented. The formalism is based on the Gross-Pitaevskii equation driven by classical light fields far detuned from atomic resonance. An approximate analytic solution is obtained and provides quantitative understanding of the atomic momentum state oscillations, as well as a simple expression for the momentum linewidth of the scattering process. The validity regime of the analytic solution is derived, and tested by three dimensional cylindrically symmetric numerical simulations.Comment: 21 pages, 10 figures. Minor changes made to documen

Osteogenesis imperfecta: from diagnosis and multidisciplinary treatment to future perspectives.

Osteogenesis imperfecta is an inherited connective tissue disorder with wide phenotypic and molecular heterogeneity. A common issue associated with the molecular abnormality is a disturbance in bone matrix synthesis and homeostasis inducing bone fragility. In very early life, this can lead to multiple fractures and progressive bone deformities, including long bone bowing and scoliosis. Multidisciplinary management improves quality of life for patients with osteogenesis imperfecta. It consists of physical therapy, medical treatment and orthopaedic surgery as necessary. Medical treatment consists of bone-remodelling drug therapy. Bisphosphonates are widely used in the treatment of moderate to severe osteogenesis imperfecta, from infancy to adulthood. Other more recent drug therapies include teriparatide and denosumab. All these therapies target the symptoms and have effects on the mechanical properties of bone due to modification of bone remodelling, therefore influencing skeletal outcome and orthopaedic surgery. Innovative therapies, such as progenitor and mesenchymal stem cell transplantation, targeting the specific altered pathway rather than the symptoms, are in the process of development

Finite temperature theory of the scissors mode in a Bose gas using the moment method

We use a generalized Gross-Pitaevskii equation for the condensate and a semi-classical kinetic equation for the noncondensate atoms to discuss the scissors mode in a trapped Bose-condensed gas at finite temperatures. Both equations include the effect of $C_{12}$ collisions between the condensate and noncondensate atoms. We solve the coupled moment equations describing oscillations of the quadrupole moments of the condensate and noncondensate components to find the collective mode frequencies and collisional damping rates as a function of temperature. Our calculations extend those of Gu\'ery-Odelin and Stringari at T=0 and in the normal phase. They complement the numerical results of Jackson and Zaremba, although Landau damping is left out of our approach. Our results are also used to calculate the quadrupole response function, which is related to the moment of inertia. It is shown explicitly that the moment of inertia of a trapped Bose gas at finite temperatures involves a sum of an irrotational component from the condensate and a rotational component from the thermal cloud atoms.Comment: 18 pages, 8 figure

Finite-temperature simulations of the scissors mode in Bose-Einstein condensed gases

The dynamics of a trapped Bose-condensed gas at finite temperatures is described by a generalized Gross-Pitaevskii equation for the condensate order parameter and a semi-classical kinetic equation for the thermal cloud, solved using $N$-body simulations. The two components are coupled by mean fields as well as collisional processes that transfer atoms between the two. We use this scheme to investigate scissors modes in anisotropic traps as a function of temperature. Frequency shifts and damping rates of the condensate mode are extracted, and are found to be in good agreement with recent experiments.Comment: 4 pages, 3 figure

Tween® preserves enzyme activity and stability in PLGA nanoparticles

Enzymes, as natural and potentially long-term treatment options, have become one of the most sought-after pharmaceutical molecules to be delivered with nanoparticles (NPs); however, their instability during formulation often leads to underwhelming results. Various molecules, including the Tween® polysorbate series, have demonstrated enzyme activity protection but are often used uncontrolled without optimization. Here, poly(lactic-co-glycolic) acid (PLGA) NPs loaded with β-glucosidase (β-Glu) solutions containing Tween® 20, 60, or 80 were compared. Mixing the enzyme with Tween® pre-formulation had no effect on particle size or physical characteristics, but increased the amount of enzyme loaded. More importantly, NPs made with Tween® 20:enzyme solutions maintained significantly higher enzyme activity. Therefore, Tween® 20:enzyme solutions ranging from 60:1 to 2419:1 mol:mol were further analyzed. Isothermal titration calorimetry analysis demonstrated low affinity and unquantifiable binding between Tween® 20 and β-Glu. Incorporating these solutions in NPs showed no effect on size, zeta potential, or morphology. The amount of enzyme and Tween® 20 in the NPs was constant for all samples, but a trend towards higher activity with higher molar rapports of Tween® 20:β-Glu was observed. Finally, a burst release from NPs in the first hour with Tween®:β-Glu solutions was the same as free enzyme, but the enzyme remained active longer in solution. These results highlight the importance of stabilizers during NP formulation and how optimizing their use to stabilize an enzyme can help researchers design more efficient and effective enzyme loaded NPs