Influence of particle size on the SARS-CoV-2 spike protein detection using IgG-capped gold nanoparticles and dynamic light scattering.

Due to the unprecedented and ongoing nature of the coronavirus outbreak, the development of rapid immunoassays to detect severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) and its highly contagious variants is an important and challenging task. Here, we report the development of polyclonal antibody-functionalized spherical gold nanoparticle biosensors as well as the influence of the nanoparticle sizes on the immunoassay response to detect the SARS-CoV-2 spike protein by dynamic light scattering. By monitoring the increment in the hydrodynamic diameter (ΔDH) by dynamic light scattering measurements in the antigen-antibody interaction, SARS-CoV-2 S-protein can be detected in only 5 min. The larger the nanoparticles, the larger ΔDH in the presence of spike protein. From adsorption isotherm, the calculated binding constant (K D ) was 83 nM and the estimated limit of detection was 13 ng/mL (30 pM). The biosensor was stable up to 90 days at 4 °C. Therefore, the biosensor developed in this work could be potentially applied as a fast and sensible immunoassay to detect SARS-CoV-2 infection in patient samples.

On the mechanical properties of PLC-bioactive glass scaffolds fabricated via BioExtrusion.

This paper addresses the mechanical characterization of polycaprolactone (PCL)-bioglass (FastOs®BG) composites and scaffolds intended for use in tissue engineering. Tissue engineering scaffolds support the self-healing mechanism of the human body and promote the regrowth of damaged tissue. These implants can dissolve after successful tissue regeneration minimising the immune reaction and the need for revision surgery. However, their mechanical properties should match surrounding tissue in order to avoid strain concentration and possible separation at the interface. Therefore, an extensive experimental testing programme of this advanced material using uni-axial compressive testing was conducted. Tests were performed at low strain rates corresponding to quasi-static loading conditions. The initial elastic gradient, plateau stress and densification strain were obtained. Tested specimens varied according to their average density and material composition. In total, four groups of solid and robocast porous PCL samples containing 0, 20, 30, and 35% bioglass, respectively were tested. The addition of bioglass was found to slightly decrease the initial elastic gradient and the plateau stress of the biomaterial scaffolds.

[Knee revision arthroplasty : cementless, metaphyseal fixation with sleeves]. / Revisionsendoprothetik des Kniegelenks : Zementfreie, metaphysäre Fixation mittels Sleeves.

OBJECTIVE: Primary and long-term fixation of cementless metaphyseal implants in knee revision arthroplasty cases with large bone defects. INDICATIONS: All tibial and femoral bone defects AORI grade 2 and 3. CONTRAINDICATIONS: Cases where stable uncemented fixation of the metaphyseal implant is not possible. SURGICAL TECHNIQUE: Pre-operative evaluation of the failure mode and implant fixation planning. After opening the joint, a synovectomy and mobilisation of medial and lateral recesses routinely performed. Testing of ligamentous stability and implant fixation undertaken before explantation. Removal of the bearing, femoral and tibial components with osteotomes or oscillating saw. Tibial diaphysis prepared with reamers, and metaphyseal preparation with broaches and stem extension. Placement of the metaphyseal broach for height with respect to the tibial joint line and rotational stability assessed. Tibial tray size and position determined before implanting the sleeve, stem and tray trial. The tibial trial provides a stable platform for analysis of the extension and flexion gaps with spacer blocks. Diaphyseal reamers used to identify the anterior femoral bow. Metaphyseal broaches used to achieve stable fixation up to the resection line marked on the handle. Distal femoral freshening cut in 5° or 7° of valgus made to accommodate distal augments as needed. Positioning of the 4-in-1 block with reconstruction of the posterior off-set and cutting for posterior augmentation. Selection of a box cut corresponding to the amount of constraint needed. Trial insert with appropriate, stem, sleeve, condylar femur and augments introduced. Bearing size, joint stability and ROM assessed. Patella alignment and the need for patella replacement or revision determined. The definitive implants are cemented at the joint surface, with metaphyseal sleeves and diaphyseal stems are uncemented. POSTOPERATIVE MANAGEMENT: Full weight bearing as tolerated, physiotherapy, lymph drainage and pain therapy are routine with no specific post-operative management required. RESULTS: Between 2007 and 2011, 193 sleeves (119 tibial/74 femoral) were implanted in 121 aspetic knee revision arthroplasties. After average of 3.6 years they were analysed clinically and radiographically. The AKSS (American Knee Society Score) increased from 88 ± 18 to 147 ± 23 points (p < 0.01). ROM (range of motion) increased from 89 ± 6° to 114 ± 4°. Overall revision rate was 11.6 %. Only 4 sleeves revised for aseptic loosening (2 % of total sleeves). An additional 10 revisions performed mainly for infection (3.3 %) or ligament instability (3.3 %).

Influence of intentional femoral component flexion in navigated TKA on gap balance and sagittal anatomy.

PURPOSE: Navigation has proven its ability to accurately restore coronal leg axis; however, for a good clinical outcome, other factors such as sagittal anatomy and balanced gaps are at least as important. In a gap-balanced technique, the size of the flexion gap is equalled to that of the extension gap. Flexion of the femoral component has been described as a theoretical possibility to balance flexion and extension gap. Aim of this study was to assess whether intentional femoral component flexion is helpful in balancing TKA gaps and in restoring sagittal anatomy. METHODS: One hundred and thirty-one patients with TKA were included in this study. Implantation was performed in a navigated, gap-balanced, tibia-first technique. The femoral component flexion needed to equal flexion to extension gap was calculated based upon the navigation data. The sagittal diameter, the anterior and posterior offset were measured pre- and postoperatively based on the lateral radiographs. Medial and lateral gaps in extension and flexion as well as flexion/extension gap differences pre- and postoperatively were analysed. Additionally range of motion (ROM) and patient satisfaction (SF 12) were obtained. RESULTS: To achieve equal flexion and extension gap, the femoral component was flexed in 120 out of 131 patients showing mean flexion of 2.9° (SD 2.2°; navigation data) and 3.1° (SD 2.0°; radiological analysis), respectively. Based on this technique, it was possible to balance the extension gap (<2 mm difference) in 130 out of 131 patients (99%) and the flexion gap in 119 out of 131 (91%). The difference between extension and flexion gap was reduced from 39 to 24 out of 131 patients (81%) on the medial side and from 69 to 28 on the lateral side (79%). The sagittal diameter was restored in 114 out of 131 cases (87%); however, anterior offset was significantly reduced by 1.3 mm (SD 3.9°), and posterior offset was significantly increased by 1.6 mm (SD 3.3°). No correlation between any navigation and radiological parameter was found with ROM and SF 12. CONCLUSIONS: The navigation-based, gap-balanced technique allows intentional flexion of the femoral component in order to balance gaps in more than 90% of primary TKA cases. Simultaneously, the sagittal diameter is restored in 87% of patients. However, to achieve equal gaps, the posterior offset is significantly increased by 1.6 mm and the femoral component is flexed by 3°. To evaluate the effect of this technique on the clinical outcome, future studies are needed. LEVEL OF EVIDENCE: II.

Pulsed ultrasound therapy accelerates the recovery of skeletal muscle damage induced by Bothrops jararacussu venom

We studied the effect of pulsed ultrasound therapy (UST) and antibothropic polyvalent antivenom (PAV) on the regeneration of mouse extensor digitorum longus muscle following damage by Bothrops jararacussu venom. Animals (Swiss male and female mice weighing 25.0 ± 5.0 g; 5 animals per group) received a perimuscular injection of venom (1 mg/kg) and treatment with UST was started 1 h later (1 min/day, 3 MHz, 0.3 W/cm², pulsed mode). Three and 28 days after injection, muscles were dissected and processed for light microscopy. The venom caused complete degeneration of muscle fibers. UST alone and combined with PAV (1.0 mL/kg) partially protected these fibers, whereas muscles receiving no treatment showed disorganized fascicules and fibers with reduced diameter. Treatment with UST and PAV decreased the effects of the venom on creatine kinase content and motor activity (approximately 75 and 48%, respectively). Sonication of the venom solution immediately before application decreased the in vivo and ex vivo myotoxic activities (approximately 60 and 50%, respectively). The present data show that UST counteracts some effects of B. jararacussu venom, causing structural and functional improvement of the regenerated muscle after venom injury.

Pulsed ultrasound therapy accelerates the recovery of skeletal muscle damage induced by Bothrops jararacussu venom.

We studied the effect of pulsed ultrasound therapy (UST) and antibothropic polyvalent antivenom (PAV) on the regeneration of mouse extensor digitorum longus muscle following damage by Bothrops jararacussu venom. Animals (Swiss male and female mice weighing 25.0 ± 5.0 g; 5 animals per group) received a perimuscular injection of venom (1 mg/kg) and treatment with UST was started 1 h later (1 min/day, 3 MHz, 0.3 W/cm(2), pulsed mode). Three and 28 days after injection, muscles were dissected and processed for light microscopy. The venom caused complete degeneration of muscle fibers. UST alone and combined with PAV (1.0 mL/kg) partially protected these fibers, whereas muscles receiving no treatment showed disorganized fascicules and fibers with reduced diameter. Treatment with UST and PAV decreased the effects of the venom on creatine kinase content and motor activity (approximately 75 and 48%, respectively). Sonication of the venom solution immediately before application decreased the in vivo and ex vivo myotoxic activities (approximately 60 and 50%, respectively). The present data show that UST counteracts some effects of B. jararacussu venom, causing structural and functional improvement of the regenerated muscle after venom injury.

GIS-based probability assessment of natural hazards in forested landscapes of Central and South-Eastern Europe.

We assessed the probability of three major natural hazards--windthrow, drought, and forest fire--for Central and South-Eastern European forests which are major threats for the provision of forest goods and ecosystem services. In addition, we analyzed spatial distribution and implications for a future oriented management of forested landscapes. For estimating the probability of windthrow, we used rooting depth and average wind speed. Probabilities of drought and fire were calculated from climatic and total water balance during growing season. As an approximation to climate change scenarios, we used a simplified approach with a general increase of pET by 20%. Monitoring data from the pan-European forests crown condition program and observed burnt areas and hot spots from the European Forest Fire Information System were used to test the plausibility of probability maps. Regions with high probabilities of natural hazard are identified and management strategies to minimize probability of natural hazards are discussed. We suggest future research should focus on (i) estimating probabilities using process based models (including sensitivity analysis), (ii) defining probability in terms of economic loss, (iii) including biotic hazards, (iv) using more detailed data sets on natural hazards, forest inventories and climate change scenarios, and (v) developing a framework of adaptive risk management.

[Ligament instability in total knee arthroplasty--causal analysis]. / Ligamentäre Instabilität bei Knie-TEP - Ursachenanalyse.

Ligament instability is a common reason for revision total knee arthroplasty (TKA). A meticulous analysis of the type of instability is very important in order to revise such a knee successfully. The objective of this study was to analyze the different reasons for ligament instability in revision TKA. A total of 135 knee revisions performed by one surgeon were analyzed pre- (clinical and x-ray) and intraoperatively for the cause of failure. X-ray analysis included the assessment of each component for position. Intraopertive analysis included stability testing in extension and 30 degrees , and 90 degrees of flexion, wear pattern, patella motion (shifting and tilting) and patella height. In 32.6 % of all cases, ligament instability was the primary reason for revision. In another 21.6%, ligament instability was identified as a secondary reason for revision. Analysis of the different instability forms showed combined instability in extension and flexion as the most common cause, followed by isolated instability in flexion (31.8%) and isolated instability in extension (9.1%). The high correlation between instability and malpositioning of the prostheses was obvious. Often, an isolated femoral malposition, in particular for rotation, was found, as well as an isolated malposition of the tibia component. In summary, ligament instability is a common reason for revision TKA. Many different forms of instability can be found either as isolated or combined instability types. Correct anatomical positioning of the components and balanced ligaments in the different extension and flexion positions are important for good clinical results, a stable joint, good function and longevity.

Polymer chain dynamics in a random environment: heterogeneous mobilities.

We present a neutron scattering investigation on a miscible blend of two polymers with greatly different glass-transition temperatures Tg. Under such conditions, the nearly frozen high-Tg component imposes a random environment on the mobile chain. The results demand the consideration of a distribution of heterogeneous mobilities in the material and demonstrate that the larger scale dynamics of the fast component is not determined by the average local environment alone. This distribution of mobilities can be mapped quantitatively on the spectrum of local relaxation rates measured at high momentum transfers.

[Conceptual and legal variations between the treatment of people with dementia receiving inpatient and ambulatory care]. / Konzeptionelle und rechtliche Varianten der Versorgung von Menschen mit Demenz zwischen ambulant und stationär.

In Germany, there clearly appears to be a gap between care carried out at home and in in-patient settings (residential nursing care). Numerous innovative projects of alternatively structured care, like for instance shared flats or group care units for people with dementia are placed in between the traditional, either home-based or institutionalised care patterns. It seems imperatively necessary to overcome the rigid separation between the inpatient sector and care carried out at home. In this article, backgrounds, necessities and perspectives of projects placed in between the traditional structures are discussed.

Bacillus subtilis sporulation and stationary phase gene expression.

Bacillus subtilis cells entering stationary phase due to nutrient deprivation have a number of options. Complex interconnected regulatory circuits govern differential gene expression patterns that channel the cell along the path it has sensed is most advantageous for survival in the environment. The actual choice depends upon the activity of an elaborate signal transduction network (the phosphorelay) that ultimately affects the activity of two key transcription factors, SpoOA and AbrB. Should the cell commit to sporulation, a temporally and spatially controlled cascade of RNA polymerase sigma factors leads to the development and release of an endospore from within the terminally differentiated, apoptotic mother cell.

Role of Cys54 in AbrB multimerization and DNA-binding activity.

The DNA-binding, global regulatory protein AbrB from Bacillus subtilis is homotetrameric in solution. Mutation of the lone cysteine present in the protomers (C54), to either a serine, tyrosine or tryptophan, abolishes DNA-binding activity in vitro and regulatory activity in vivo. The effect of these changes is not due to abrogation of disulfide bond formation since it can be shown biochemically that none of the C54 residues participates in disulfide bond formation. It is unlikely that C54 is involved in direct contact with DNA targets. Rather, it appears that the role of C54 is to provide a nucleophilic center required for proper spatial orientation of the polypeptide subunits.

DNA-binding activity of amino-terminal domains of the Bacillus subtilis AbrB protein.

Two truncated variants of AbrB, comprising either its first 53 (AbrBN53) or first 55 (AbrBN55) amino acid residues, were constructed and purified. Noncovalently linked homodimers of the truncated variants exhibited very weak DNA-binding activity. Cross-linking AbrBN55 dimers into tetramers and higher-order multimers (via disulfide bonding between penultimate cysteine residues) resulted in proteins having DNA-binding affinity comparable to and DNA-binding specificity identical to those of intact, wild-type AbrB. These results indicate that the DNA recognition and specificity determinants of AbrB binding lie solely within its N-terminal amino acid sequence.

Novel DNA binding domain and genetic regulation model of Bacillus subtilis transition state regulator abrB.

We have determined the high resolution NMR solution structure of the novel DNA binding domain of the Bacillus subtilis transition state regulator AbrB. Comparisons of the AbrB DNA binding domain with DNA binding proteins of known structure show that it is a member of a completely novel class of DNA recognition folds that employs a dimeric topology for cellular function. This new DNA binding conformation is referred to as the looped-hinge helix fold. Sequence homology investigations show that this DNA binding topology is found in other disparately related microbes. Structural analysis of the AbrB DNA binding domain together with bioanalytical and mutagenic data of full length AbrB allows us to construct a general model that describes the genetic regulation properties of AbrB.

Are guidelines followed in Helicobacter pylori diagnosis and therapy? An inquiry among gastroenterologists, referring physicians and patients in Munich.

BACKGROUND AND STUDY AIMS: Attempts to standardize Helicobacter pylori (Hp) diagnosis and therapy have led to the publication of guidelines by various national gastroenterological societies in Europe and the USA. However, little information is available either regarding the compliance of gastroenterologists and referring physicians with these guidelines, or regarding the patients' perspective. PATIENTS AND METHODS: A retrospective analysis was conducted of all outpatient upper gastrointestinal endoscopy reports for a one-month period in eleven different centers (two university hospitals and nine private practice gastroenterology offices) with a total of 24 gastroenterologists. Endoscopy reports from patients wit the indications of reflux, diarrhea, and tumors were excluded. Diagnoses and treatment recommendations given by gastroenterologists were recorded. Questionnaires concerning Hp diagnosis, treatment indications and performance, and follow-up were sent to referring physicians and patients. RESULTS: A total of 772 endoscopy reports were included in the study; analyzable questionnaires were returned by 287 referring physicians (47%) and by 265 patients (59%). Gastroenterologists recommended Hp eradication in all ulcers and in 29% of gastritis/nonulcer dyspepsia (NUD) cases. Referring physicians thought that 94% of ulcers should be treated by Hp eradication, which was also considered to be an absolute and relative indication in NUD by 15% and 53% of the referring physicians, respectively. Among the patients who replied, 52% had received Hp eradication regimens; ulcers were found in 22% of the total patient group. Check-up examinations after Hp therapy were considered necessary by 75% of the referring physicians, but only 22% of the responding patients actually underwent some form of check-up (upper gastrointestinal endoscopy in 91%). CONCLUSIONS: Gastroenterologists and (to a somewhat lesser extent) referring physician appear to be following the current guidelines for Hp treatment. As expected, two thirds of referring physicians consider NUD to be absolute or relative indication for Hp eradication. Check-up examinations are apparently being performed less frequently than recommended.

Synergistic kinetic interactions between components of the phosphorelay controlling sporulation in Bacillus subtilis.

The four individual phosphotransfer steps in the multicomponent phosphorelay system controlling sporulation in Bacillus subtilis have been characterized kinetically using highly purified samples of the individual protein components in vitro. The autophosphorylation of KinA is the initial occurrence, and a divalent metal ion is required. KinA-mediated phosphotransfer, which displays a 57,000-fold preference (kcat/Km) for catalysis of Spo0F-P formation relative to Spo0A-P formation, is shown to proceed via a hybrid ping-pong/sequential mechanism with pronounced (> or = 40-fold) substrate synergism by Spo0F of KinA autophosphorylation. In addition, evidence is presented for formation of an abortive KinA.Spo0F complex. Kinetic parameters derived for Spo0F-P and Spo0A as substrates for Spo0B, the second phosphotransferase in the phosphorelay chain, indicate that Spo0B-mediated production of Spo0A-P is 1.1-million-fold more efficient (kcat/KSpo0A) than the direct KinA-mediated process. A rationale is presented for a four component cascade as the means for controlling sporulation, which focuses on the utility of synergistic interactions among the phosphorelay components that may be modulated by environmental stimuli.