Contrast enhancement with uranyl acetate allows quantitative analysis of the articular cartilage by microCT: Application to mandibular condyles in the BTX rat model of disuse

Microcomputed tomography (microCT) is well adapted to quantitative analysis of calcified tissues but soft tissues (such as cartilage) are radiolucent and need a contrast enhancement procedure for microCT. We developed a "staining" method allowing microCT imaging of articular cartilage using uranyl acetate (UA). The method was used to see whether adult rats with a botulinum toxin (BTX) injection in masticatory muscles present a change at the condylar cartilage of the mandible in association with a localized trabecular bone loss. Human femoral head samples were used to develop the enhanced contrast method using UA or lanthanides (recently proposed as a substitute for UA). The method was then applied to the condylar cartilage of rat mandibles. Mature male rats (n=11) were randomized into 2 groups: control (CTRL; n=4) and BTX group (n=7). Rats of the BTX group received a single injection of BTX into the right M. Masseter and M. Temporalis. Rats of the CTRL group were similarly injected with saline. Rats were sacrificed 4 weeks after injection. Condyles were harvested, fixed in formalin and immersed in UA. MicroCT was performed for bone and cartilage measurements. After UA impregnation, articular cartilage of human femoral head samples was clearly seen on its full thickness whereas lanthanides produced a much less pronounced contrast, with a faint labeling at the upper layer. In BTX rats, microCT analysis showed a significant bone loss at the right condyles. After UA, the whole thickness of articular cartilage was clearly evidenced. Cartilage thickness measurement showed no difference when comparing the right with the left sides of the BTX group nor between the two sides of the CTRL group. Contrast enhancement with UA is a simple technique allowing quantitative analysis of cartilage by microCT.290 words

Traitement avancé de micropolluants organiques dans l'eau par couplage entre adsorption sur charbon actif et ozonation catalysée

Traitement avancé de micropolluants organiques dans l'eau par couplage entre adsorption sur charbon actif et ozonation catalysé

Human macrophages and osteoclasts resorb β-tricalcium phosphate in vitro but not mouse macrophages

β-TCP is a resorbable bony biomaterial but its biodegradation mechanisms in vivo remains unclear. Osteoclast can resorb β-TCP but a role for macrophages has also been suggested by in vivo studies. However no in vitro study has clearly evidenced the action of macrophages in the resorption process. We prepared flat β-TCP tablets with a smooth surface to investigate the in vitro capability of murine (RAW 264.7) and human macrophage cells (PBMCs) to resorb the biomaterial. In parallel, these cells were differentiated into multinucleated osteoclasts with M-CSF and RANK-L. The action of these cells was evaluated by scanning electron microscopy and Raman microspectroscopy after a 21 day culture on the tablets. Human macrophages and osteoclasts derived from PBMCs appeared able to resorb β-TCP by forming resorption pits at the surface of the flat tablets. RAW macrophages were unable to resorb β-TCP but they exhibited this possibility when they have been differentiated into osteoclasts. These cells can engulf β-TCP grains in their cytoplasm as evidenced by light and TEM microscopy with production of carbonic anhydrase (revealed by the immunogold technique in TEM). The resorbed areas were characterized by severe degradation of the grains showing speckled and stick-like aspects indicating a chemical corrosion. The effect was maximal at the grain boundaries which have a slightly different chemical composition. Changes in the Raman spectrum were observed between the resorbed and un-resorbed β-TCP suggesting crystal modifications. In contrast, un-differentiated murine macrophages were not able to chemically attack β-TCP and no resorption pit was observed. RAW cell is not a representative model of the macrophage-biomaterial interactions that occur in human. This in vitro study evidences that both human osteoclasts and macrophages represent active cell populations capable to resorb β-TCP

Secondary Endothelial Keratoplasty—A Narrative Review of the Outcomes of Secondary Corneal Endothelial Allografts

Background: We review the literature on the efficacy and safety outcomes of secondary Descemet stripping endothelial keratoplasty (DSEK) and Descemet membrane endothelial keratoplasty (DMEK). Methods: Literature search of English-written publications up to September 27, 2020 in PubMed database, using the terms "endothelial keratoplasty" in combination with keywords "secondary" or "repeat." In addition, we manually searched the references of the primary articles. Results: Twenty-seven studies (n = 651 eyes) were retained and reviewed, including 10 studies on repeat DSEK, 8 studies on repeat DMEK, 6 studies of DMEK following DSEK, and 3 studies of DSEK after failed DMEK. All studies reported significant improvement in visual acuity after secondary endothelial keratoplasty (EK). Twelve studies compared visual outcomes between primary and secondary EK, reporting conflicting findings. Sixteen studies reported endothelial cell loss rates after secondary EK, and only 1 study reported significantly increased endothelial cell loss rates compared with primary EK. Allograft rejection episodes occurred in 1.8% of eyes (range, 0%-50%). Six studies compared complication rates between primary and secondary EK eyes, and only 1 study found a higher median number of complications. However, 2 studies reported higher regraft failure rates compared with primary EK eyes. Conclusions: Secondary EK is surgically feasible and renders significant visual improvement after failed primary EK, although it is not clear whether visual outcomes and allograft survival are comparable with primary EK, raising the question of whether secondary EK eyes are "low risk" as primary EK eyes. Further larger, prospective studies are encouraged to obtain additional quality data on secondary corneal endothelial allotransplantation.info:eu-repo/semantics/publishedVersio

Improving Mechanical Properties and Reaction to Fire of EVA/LLDPE Blends for Cable Applications with Melamine Triazine and Bentonite Clay

The high flame-retardant loading required for ethylene-vinyl acetate copolymer blends with polyethylene (EVA-PE) employed for insulation and sheathing of electric cables represents a significant limitation in processability and final mechanical properties. In this work, melamine triazine (TRZ) and modified bentonite clay have been investigated in combination with aluminum trihydroxide (ATH) for the production of EVA-PE composites with excellent fire safety and improved mechanical properties. Optimized formulations with only 120 parts per hundred resin (phr) of ATH can achieve self-extinguishing behavior according to the UL94 classification (V0 rating), as well as reduced combustion kinetics and smoke production. Mechanical property evaluation shows reduced stiffness and improved elongation at break with respect to commonly employed EVA-PE/ATH composites. The reduction in filler content also provides improved processability and cost reductions. The results presented here allow for a viable and halogen-free strategy for the preparation of high performing EVA-PE composites

Outcomes of Cystoid Macular Edema Following Descemet's Membrane Endothelial Keratoplasty in a Referral Center for Keratoplasty in Spain: Retrospective Study

The aim of this study was to analyze the outcomes of eyes with visually significant cystoid macular œdema (vs-CMO) after Descemet membrane endothelial keratoplasty (DMEK) in a referral center for keratoplasty in Spain. We conducted a retrospective, single-surgeon case series of eyes that developed post-DMEK vs-CMO performed between January 2011 and December 2020. Data collected included: indication for DMEK; biometric data; ocular comorbidities; past medical history; time to detection of vs-CMO after DMEK (T, weeks); best-corrected visual acuity (BCVA, logMAR) and central retinal thickness (CRT, µm) at diagnosis of vs-CMO, after resolution of CMO, and at last follow-up; and management strategy. Main outcomes analyzed were incidence of vs-CMO, improvement in BCVA and CRT after treatment of vs-CMO. Of 291 consecutive DMEK surgeries, 14 eyes of 13 patients (4.8%) developed vs-CMO. Five patients (38.5%) had history of CMO, and 28.6% of eyes had ophthalmic comorbidities. Median (P25-P75) T was 4 (3-10) weeks. Treatment success was observed in 12/13 eyes (92.3%), two of which required second-line treatment. In successful cases (median time-to-resolution 3.0 (2.0-3.5) months), median BCVA improved from 0.60 (0.40-0.80) logMAR to 0.30 (0.15-0.40) logMAR (p = 0.002) after treatment, and median CRT improved from 582.5 (400.0-655.0) µm to 278.0 (258.0-294.0) µm (p = 0.005). In our study, we found a 4.8% rate of post-DMEK vs-CMO, with most cases occurring in the first 3 months after surgery. Good functional and anatomical outcomes are expected in most eyes, without treatment-related complications or implications in graft outcomes. Additional studies are encouraged to determine a standardized protocol for post-DMEK vs-CMO.info:eu-repo/semantics/publishedVersio

All-in-one trifunctional strategy: A cell adhesive, bacteriostatic and bactericidal coating for titanium implants

Strategies to inhibit initial bacterial adhesion are extremely important to prevent infection on biomaterial surfaces. However, the simultaneous attraction of desired eukaryotic cells remains a challenge for successful biomaterial-host tissue integration. Here we describe a method for the development of a trifunctional coating that repels contaminating bacteria, kills those that adhere, and promotes osteoblast adhesion. To this end, titanium surfaces were functionalized by electrodeposition of an antifouling polyethylene glycol (PEG) layer and subsequent binding of a peptidic platform with cell-adhesive and bactericidal properties. The physicochemical characterization of the samples via SEM, contact angle, FTIR and XPS analysis verified the successful binding of the PEG layer and the biomolecules, without altering the morphology and topography of the samples. PEG coatings inhibited protein adsorption and osteoblast-like (SaOS-2) attachment; however, the presence of cell adhesive domains rescued osteoblast adhesion, yielding higher values of cell attachment and spreading compared to controls (p < 0.05). Finally, the antibacterial potential of the coating was measured by live/dead assays and SEM using S. sanguinis as a model of early colonizer in oral biofilms. The presence of PEG layers significantly reduced bacterial attachment on the surfaces (p < 0.05). This antibacterial potential was further increased by the bactericidal peptide, yielding values of bacterial adhesion below 0.2% (p < 0.05). The balance between the risk of infection and the optimal osteointegration of a biomaterial is often described as “the race for the surface”, in which contaminating bacteria and host tissue cells compete to colonize the implant. In the present work, we have developed a multifunctional coating for a titanium surface that promotes the attachment and spreading of osteoblasts, while very efficiently inhibits bacterial colonization, thus holding promise for application in bone replacing applications.Peer ReviewedPostprint (author's final draft

Effect of ionic strength on rheological behavior of polymer-like cetyltrimethylammonium tosylate micellar solutions

Dieser Beitrag ist mit Zustimmung des Rechteinhabers aufgrund einer (DFG geförderten) Allianz- bzw. Nationallizenz frei zugänglich.This publication is with permission of the rights owner freely accessible due to an Alliance licence and a national licence (funded by the DFG, German Research Foundation) respectively.The influence of ionic strength on the rheological properties of polymer-like aqueous micellar solutions of cetyltrimethylammonium tosylate (CTAT) containing different salts (KCl, KBr, (COONa)2, K2SO4 or K3PO4) is investigated. The rheological behavior of the solutions is analyzed above the concentration where a micellar entanglement network is formed, varying surfactant and salt concentration, salt counterion valency and temperature. A master curve of the linear viscoelastic properties is obtained by multiple superposition of time, temperature, salt type, and surfactant and salt concentration. Application of the existent kinetic theory provides information suggesting that the micellar solutions are in the fast breaking regime (i.e., the relaxation is kinetically controlled) regardless of salt type and concentration. Moreover, these solutions exhibit shear-banding flow with a reduced stress plateau (σ/G0, being σ and G0 the shear stress and the plateau modulus, respectively) that increases with salt content and counterion valency. The zero-shear viscosity (η0) and the main relaxation time (τC) diminish with increasing salt content according to a step-like function, in which the number of steps increases with the salt counterion valence. In contrast, G0 only increases slightly with increasing salt content for the five salts employed. These results are discussed in terms of ionic strength and screening of the electrostatic-interactions caused by the addition of salt. In addition, it was found that the influence of anions on the viscoelastic properties of the polymer-like micelles follows the Hofmeister series commonly encountered in macromolecular and biological systems. This finding opens a challenge for scientists in the experimental and theoretical fields

Prognostic model for early acute rejection after liver transplantation

Hepatic graft rejection is a common complication after liver transplantation (LT), with a maximum incidence within the first weeks. The identification of high-risk patients for early acute rejection (EAR) might be useful for clinicians. A series of 133 liver graft recipients treated with calcineurin inhibitors was retrospectively assessed to identify predisposing factors for EAR and develop a mathematical model to predict the individual risk of each patient. The incidence of EAR (< or =45 days after LT) was 35.3%. Multivariate analysis showed that recipient age, underlying liver disease, and Child's class before LT were independently associated with the development of EAR. Combining these 3 variables, the following risk score for the development of EAR was obtained: EAR score [F(x)] = 2.44 + (1.14 x hepatitis C virus cirrhosis) + (2.78 x immunologic cirrhosis) + (2.51 x metabolic cirrhosis)--(0.08 x recipient age in years) + (1.65 x Child's class A) [corrected]. Risk for rejection = e(F(x))/1 + e(F(x)). The combination of age, cause of liver disease, and Child's class may allow us to predict the risk for EAR