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.

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.

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.

Sporulation in prokaryotes and lower eukaryotes.

During the past year, highlights in sporulation research include the demonstration that phosphorylation of SpoOA is a critical factor in Bacillus subtilis development; the identification of C alpha proteins, adenylyl cyclase and protein kinase A genes in Dictyostelium; proof that an endogenous antisense RNA regulates gene expression in Dictyostelium; and characterization of a second type of differentiated cell in Myxococcus.

Signal transduction in Bacillus subtilis sporulation.

The initiation of sporulation in Bacillus subtilis is regulated by a signal transduction system leading to activation (by phosphorylation) of the Spo0A transcription factor. Activated Spo0A controls the expression of genes encoding different RNA polymerase sigma factors, whose synthesis and activities are related to morphological events and intercompartmental communication between the developing forespore and the mother cell.

[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 %).

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.

Sequence of the Bacillus subtilis glutamine synthetase gene region.

The nucleotide sequence of the glutamine synthetase (GS) region of Bacillus subtilis has been determined and found to contain several unique features. An open reading frame (ORF) upstream of the GS structural gene is part of the same operon as GS and is involved in regulation. Two downstream ORFs are separated from glnA by an apparent Rho-independent termination site. One of the downstream ORFs encodes a very hydrophobic polypeptide and contains its own potential RNA polymerase and ribosome-binding sites. The derived amino acid (aa) sequence of B. subtilis GS is similar to that of several other prokaryotes, especially to the GS of Clostridium acetobutylicum. The B. subtilis and C. acetobutylicum enzymes differ from the others in the lack of a stretch of about 25 aa as well as the presence of extra cysteine residues in a region known to contain regulatory as well as catalytic mutations. The region around the tyrosine residue that is adenylylated in GS from many species is fairly similar in the B. subtilis GS despite its lack of adenylylation.

Spo0A activates and represses its own synthesis by binding at its dual promoters.

The Spo0A protein of Bacillus subtilis controls the onset of sporulation by regulating transcription of various genes in both positive and negative manners depending on the promoters affected. The expression of the spo0A gene occurs from two promoters (Pv,Ps), separated by 148 bp, and transcription switches from Pv to Ps early in the sporulation program. DNase I footprint analysis of the spo0A promoter region revealed three distinct sites of Spo0A binding: -4 to +19 relative to Pv, -17 to +1 relative to Ps, and a region between Pv and Ps. The Pv region and the region between the two promoters was sufficient for repression of Pv. Induction of Ps also required these regions which are upstream of -52 relative to Ps. Mutant Spo0A proteins containing asp----asn mutations at asp10 and asp56 were inactive in repression of the abrB promoter in vivo yet still retained DNA-binding activity. The results presented are consistent with a model in which the phosphorylated form of Spo0A acts directly at its promoters to achieve induction of Ps and repression of Pv. These effects at the spo0A promoter were independent of the presence of the major kinase, KinA.

The effect of supercoiling on the in vitro transcription of the spoIIA operon from Bacillus subtilis.

The spoIIA operon codes for an alternative sigma factor which appears in the early stages of a sigma factor expression cascade during sporulation in Bacillus subtilis. We have used a single round in vitro transcription assay to probe requirements for transcription initiation at the spoIIA promoter. Core RNA polymerase or holoenzyme containing sigma A was reconstituted with sigma H protein and used to transcribe the spoIIA promoter. Formation of heparin resistant transcription initiation complexes required that the spoIIA template be supercoiled. Topoisomers of the spoIIA template were created and transcribed at various temperatures. Changes in the superhelicity of template DNA had a significant influence on the amount of transcription complexes formed at the spoIIA promoter.

Osmotically induced natriuresis and blood pressure response involves angiotensin AT1 receptors in the subfornical organ.

OBJECTIVE: In the present study we tested the hypothesis of whether the centrally induced natriuresis and blood pressure increase after intracerebroventricular injection of hypertonic saline involves the subfornical organ, as suggested by the occurrence of osmosensitive cells as well as a high concentration of angiotensin II receptors in this brain area. METHODS: All experiments were performed in conscious Wistar rats. A chronic cannula was inserted into the lateral brain ventricle for intracerebroventricular injection and a chronic indwelling intracranial guide cannula for microinjection was placed in the subfornical organ. In addition, the rats were provided with ureter catheters for urine collection. RESULTS: Intracerebroventricular injections of hypertonic saline (0.3 mol/l; n = 7) increased renal sodium excretion from 180.0 +/- 30.0 to 279.0 +/- 34.0 mol/l/60 min (P < 0.001) accompanied by an increase in mean arterial pressure of 8.3 +/- 1.2 mmHg (P < 0.01). No change in urinary volume was observed. After injection of the specific AT1 receptor antagonist, losartan, into the subfornical organ (5 micrograms/200 nl; n = 8) the natriuresis and blood pressure response to intracerebroventricular hypertonic saline was completely abolished. Control injections of losartan into areas adjacent to the subfornical organ had no effect on the responses to hypertonic saline. CONCLUSION: Our results suggest that the centrally induced natriuresis and blood pressure responses to hypertonic saline are mediated by an angiotensinergic mechanism involving the subfornical organ.

Control of the initiation of sporulation in Bacillus subtilis by a phosphorelay.

Sporulation in Bacillus subtilis is a developmental process induced as a response to nutritional stress. Activation of sporulation-specific gene transcription is under the control of the spoOA gene product. The SpoOA protein and the SpoOF protein are both homologous to response regulator proteins of two-component regulatory systems which control bacterial responses to a variety of environmental challenges. Response regulators are activated by specific kinases which phosphorylate them. In this study, it was shown that phosphorylation of SpoOA occurs via a phosphotransferase which is the product of the spoOB locus. The phosphodonor in this reaction is the phosphorylated form of SpoOF. It is postulated that SpoOF acts as a secondary messenger that can be phosphorylated by a variety of kinases depending on the particular environmental stress. The series of phosphate transfer reactions in this system is called a phosphorelay. The end product of this series of reactions is SpoOA approximately P which is shown to have greater affinity for the DNA target, the OA box, of SpoOA on the abrB promoter than the unphosphorylated form. SpoOA approximately P, but not SpoOA, was shown to be an activator of transcription of the spoIIA operon which codes for the sporulation-specific sigma factor sigma F. Thus, the initiation of sporulation is dependent on SpoOA approximately P which arises through the phosphorelay and which acts as a transcription factor to repress certain genes, e.g. abrB, and activate others, e.g. spoIIA.

Controlled trial of two keto acid supplements on renal function, nutritional status, and bone metabolism in uremic patients.

In this matched, controlled study, two different types of EAA/KA supplements were compared in uremic patients fed a 30 g protein restricted diet. The patients were paired for age, sex, and underlying renal disease. The supplement with the higher BCKA content resulted in an improvement of renal function, bone metabolism, and a normalization of plasma BCAA concentrations. With both supplements, adequate nutritional status of the patients was maintained. We conclude that the BCKA content of the supplement is of considerable importance for uremic patients on low protein diets.

Low-protein diet supplemented by keto acids in chronic renal failure: a prospective controlled study.

In this prospective controlled study, a 30-g protein-restricted diet supplemented by keto acids resulted in a delayed rate of progression of chronic renal failure. The effect of this treatment differed according to the underlying renal disease. The rate of progression of chronic renal failure was delayed by a factor of at least 2. A need for long-term observations to quantify the effectiveness of this therapy is shown. A new pragmatic approach to the evaluation of long-term studies in patients with chronic renal failure is demonstrated.

Predictability of the progression of chronic renal failure.

The progression of chronic renal failure has been claimed to be predictable by means of mathematical models. The present study assesses, in 110 adult patients, the prediction error caused by the application of these models. The study shows that the prediction error has a wide range, which indicates that these models should be used with caution for prediction purposes in individual patients. Improvements of the models are proposed, and a new approach is demonstrated.

Juxtaglomerular apparatus of the human kidney: correlation between structure and function.

Electron microscopic and morphometric evaluation of the juxtaglomerular apparatus (JGA) of the human kidney showed the following: (1) The JGA of the human kidney consists of the epithelioid cells of afferent and efferent arterioles, the Goormaghtigh cells, and the macula densa, and it is abundantly supplied with sympathetic nerves. (2) The macula densa is in contact with the juxtaglomerular cell complex (JGC), the endocrine part of the JGA, via the Goormaghtigh cell field. The surface area of the macula densa is much larger than is the contact area with the JGA, totalling, in the healthy human kidney, some 66 cm2. (3) The total volume of all JGC's is 26 to 40 mm3. (4) Morphometric investigations of the JGC showed that appropriate stimulation by a decrease in the intrarenal or systemic blood pressure led to hypertrophy and hyperplasia of the JGC, which, in extreme cases, may also lead to a transformation of both the Goormaghtigh cells and mesangium cells into epithelioid cells.

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.

Clotting in dialyzers due to low pH of dialysis fluid.

During November and December 1975 frequent clotting occurred in the extracorporeal circuits of different dialyzers used in our unit. After installation of new automatically regenerating ion exchange resin columns,, the pH of deionized water ranged from 4.2 to 8.4 during 24 hr periods. Dialysate pH ranged between 5.3 and 8.2, and the patient's whole blood pHs ranged from 7.15 to 7.4 at the dialyzer inlet and from 6.2 (!) to 7.4 at the outlet. A strong correlation was seen between the acidity of the water and the frequency of clotting, and it was considered possible that the clotting was due to structural changes within the heparin molecules induced by the low pH. Following the introduction of an automatic titration device into our dialyzate preparation system, clotting with consecutive blood loss and subjective clinical symptoms have disappeared.

[Autoregulation of kidney circulation, glomerular filtration rate and plasma renin activity in spontaneously hypertensive rats and normotensive Wistar rats]. / Autoregulation der Nierendurchblutung, der glomerulären Filtrationsrate und der Plasmareninaktivität in spontan hypertensiven Ratten und normotensiven Wistar-Ratten.

The autoregulation of renal blood flow (RBF), glomerular filtration rate (GFR) and the pressure dependent renin release into the circulation were studied in conscious chronically instrumented spontaneously hypertensive rats (SHR) and normotensive Wistar rats. Renal perfusion pressure was lowered by means of a suprarenal inflatable cuff on the abdominal aorta and was lowered in pressure steps of 10 mm Hg. Breakoff points for RBF- and GFR-autoregulation as well as the threshold for renin release were calculated using non-linear regression (breakpoint analysis). Wistar rats autoregulated RBF and GFR in a range between 110 and 90 mm Hg (breakoff points: RBF 88 +/- 2 mm Hg; GFR 92 +/- 3 mm Hg). Plasma-renin activity (PRA) showed a threshold of activation at 89 +/- 8 mm Hg. Breakoff points and threshold of renin release did not differ significantly from each other. SHR autoregulated RBF and GFR in a range between 160 and 100 mm Hg (breakoff points: RBF 104 +/- 6 mm Hg; GFR 99 +/- 4 mm Hg). The PRA increase had a threshold at 119 +/- 6 mm Hg. Breakoff points of RBF- and GFR-autoregulation did not differ significantly. In SHR the threshold of renin release was at a significantly higher pressure than the breakoff point of GFR-autoregulation. The comparison between Wistar rats and SHR revealed a significant shift of the RBF-autoregulation curve and the pressure-dependent renin release of SHR towards higher pressures (p < 0.05). The early increase of PRA in SHR suggests a role of the renin-angiotensin-system (RAS) in the autoregulation of GFR in SHR. Wistar rats seem to autoregulate GFR independently of the RAS. An activation of the sympathetic nervous system might take part in the rightward shift of the RBF- and GFR-autoregulation curve in SHR. The role of this altered autoregulatory pattern in the development of genetic hypertension remains to be investigated.

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.