Incubation In Saline Research Articles

Effect of the Addition of Inorganic Fillers on the Properties of Degradable Polymeric Blends for Bone Tissue Engineering.

Bone tissue exhibits self-healing properties; however, not all defects can be repaired without surgical intervention. Bone tissue engineering offers artificial scaffolds, which can act as a temporary matrix for bone regeneration. The aim of this study was to manufacture scaffolds made of poly(lactic acid), poly(ε-caprolactone), poly(propylene fumarate), and poly(ethylene glycol) modified with bioglass, beta tricalcium phosphate (TCP), and/or wollastonite (W) particles. The scaffolds were fabricated using a gel-casting method and observed with optical and scanning electron microscopes. Attenuated total reflectance-Fourier transform infrared (ATR-FTIR), differential scanning calorimetry (DSC), thermogravimetry (TG), wettability, and degradation tests were conducted. The highest content of TCP without W in the composition caused the highest hydrophilicity (water contact angle of 61.9 ± 6.3°), the fastest degradation rate (7% mass loss within 28 days), moderate ability to precipitate CaP after incubation in PBS, and no cytotoxicity for L929 cells. The highest content of W without TCP caused the highest hydrophobicity (water contact angle of 83.4 ± 1.7°), the lowest thermal stability, slower degradation (3% mass loss within 28 days), and did not evoke CaP precipitation. Moreover, some signs of cytotoxicity on day 1 were observed. The samples with both TCP and W showed moderate properties and the best cytocompatibility on day 4. Interestingly, they were covered with typical cauliflower-like hydroxyapatite deposits after incubation in phosphate-buffered saline (PBS), which might be a sign of their excellent bioactivity.

Engineering a microparticle-loaded rough membrane for guided bone regeneration modulating osteoblast response without inducing inflammation

Guided bone regeneration (GBR) is a widely used procedure that prevents the fast in-growth of soft tissues into bone defect. Among the different types of membranes, the use of collagen membranes is the gold standard. However, these membranes are implanted in tissue location where a severe acute inflammation will occur and can be negatively affected. The aim of this study was to develop a collagen-based membrane for GBR that incorporated alginate-hydroxyapatite microparticles. Membranes were manufactured using collagen type I and gelatin and alginate-hydroxyapatite microparticles. Membranes were assessed in terms of topography by scanning electron microscopy and confocal microscopy; stability by swelling after an overnight incubation in saline and enzymatic degradation against collagenase and mechanical properties by tensile tests. Furthermore, the biological response was assessed with SaOs-2 cells and THP-1 macrophages to determine alkaline phosphatase activity and inflammatory cytokine release. Our results showed that the incorporation of different percentages of these microparticles could induce changes in the surface topography. When the biological response was analyzed, either membranes were not cytotoxic to THP-1 macrophages or to SaOs-2 cells and they did not induce the release of pro-inflammatory cytokines. However, the different surface topographies did not induce changes in the macrophage morphology and the release of pro- and anti-inflammatory cytokines, suggesting that the effect of surface roughness on macrophage behavior could be dependent on other factors such as substrate stiffness and composition. Collagen-gelatin membranes with embedded alginate-hydroxyapatite microparticles increased ALP activity, suggesting a positive effect of them on bone regeneration, remaining unaffected the release of pro- and anti-inflammatory cytokines.

THE INFLUENCE OF QUERCETIN ON THE PRODUCTION OF REACTIVE OXYGEN-NITROGEN FORMS IN THE STRUCTURE OF THE INTERSTITIAL SPACE OF RAT TESTICLES WITH LONG-TERM EFFECT OF TRIPTORELIN

Quercetin is a flavonoid commonly found in fruits, vegetables, and seeds. Flavonoids can help prevent cardiovascular diseases, reduce the risk of degenerative brain processes and cancer. Studies have shown that blocking the synthesis of luteinising hormone can lead to oxidative stress in the liver, heart, and salivary glands of rats. The purpose of this study was to assess alterations in the interstitial space of rat testes, identify sources of nitric oxide production, and measure the intensity of oxidative stress in the testes during long-term experimental central blocking of luteinising hormone synthesis by tryptorelin. The study was conducted on 15 sexually mature male white rats. The animals were divided into two groups. The first group (control) received a subcutaneous injection of 0.9% sodium chloride solution. The second group (experimental) received a subcutaneous injection of tryptorelin at a dose of 0.3 mg/kg of active ingredient for 365 days, with simultaneous addition of quercetin to the diet, which was administered orally through a gastric tube three times a day. Total nitric oxide production was assessed by measuring the activity of total NO synthase (gNOS). The activity of gNOS was determined by the increase in nitrite (NO2-) after incubation in Tris-buffered saline. The nitrite concentration was determined using the Gris-Ilosvay reagent at a wavelength of 540 nm. The activity of the inducible (iNOS) and constitutive (cNOS) isoforms was also determined using a selective iNOS inhibitor, aminoguanidine hydrochloride. The production of superoxide anion radical (O2--) was measured by the increase in the formation of diformazan resulting from the reaction of O2-- with nitroblue tetrazolium after incubation in a buffered solution containing sodium hydroxide. The administration of quercetin mitigates the adverse effects of tryptorelin on the structural and functional components of the connective tissue in the rat testes. This effect is observed on day 365 and is characterised by fibrosis and impaired nitric oxide production by constitutive isoforms of NO synthase.

Biomimetic Electrospun Scaffold-Based In Vitro Model Resembling the Hallmarks of Human Myocardial Fibrotic Tissue.

Adverse remodeling post-myocardial infarction is hallmarked by the phenotypic change of cardiac fibroblasts (CFs) into myofibroblasts (MyoFs) and over-deposition of the fibrotic extracellular matrix (ECM) mainly composed by fibronectin and collagens, with the loss of tissue anisotropy and tissue stiffening. Reversing cardiac fibrosis represents a key challenge in cardiac regenerative medicine. Reliable in vitro models of human cardiac fibrotic tissue could be useful for preclinical testing of new advanced therapies, addressing the limited predictivity of traditional 2D cell cultures and animal in vivo models. In this work, we engineered a biomimetic in vitro model, reproducing the morphological, mechanical, and chemical cues of native cardiac fibrotic tissue. Polycaprolactone (PCL)-based scaffolds with randomly oriented fibers were fabricated by solution electrospinning technique, showing homogeneous nanofibers with an average size of 131 ± 39 nm. PCL scaffolds were then surface-functionalized with human type I collagen (C1) and fibronectin (F) by dihydroxyphenylalanine (DOPA)-mediated mussel-inspired approach (PCL/polyDOPA/C1F), in order to mimic fibrotic cardiac tissue-like ECM composition and support human CF culture. BCA assay confirmed the successful deposition of the biomimetic coating and its stability during 5 days of incubation in phosphate-buffered saline. Immunostaining for C1 and F demonstrated their homogeneous distribution in the coating. AFM mechanical characterization showed that PCL/polyDOPA/C1F scaffolds, in wet conditions, resembled fibrotic tissue stiffness with an average Young's modulus of about 50 kPa. PCL/polyDOPA/C1F membranes supported human CF (HCF) adhesion and proliferation. Immunostaining for α-SMA and quantification of α-SMA-positive cells showed HCF activation into MyoFs in the absence of a transforming growth factor β (TGF-β) profibrotic stimulus, suggesting the intrinsic ability of biomimetic PCL/polyDOPA/C1F scaffolds to sustain the development of cardiac fibrotic tissue. A proof-of-concept study making use of a commercially available antifibrotic drug confirmed the potentialities of the developed in vitro model for drug efficacy testing. In conclusion, the proposed model was able to replicate the main hallmarks of early-stage cardiac fibrosis, appearing as a promising tool for future preclinical testing of advanced regenerative therapies.

The Choice of the Most Appropriate Suture Threads for Pancreatic Anastomoses on the Basis of Their Mechanical Characteristics.

The choice of the most appropriate suture threads for pancreatic anastomoses may play an important role in reducing the incidence of post-operative pancreatic fistula (POPF). The literature on this topic is still not conclusive. The aim of this study was to analyze the mechanical characteristics of suture materials to find the best suture threads for pancreatic anastomoses. A single-axial electromagnetic actuation machine was used to obtain the stress-deformation relationship curves and to measure both the ultimate tensile strength (UTS) and the Young's modulus at the 0-3% deformation range (E0-3) of four different suture materials (Poliglecaprone 25, Polydioxanone, Polyglactin 910, and Polypropylene) at baseline and after incubation in saline solution, bile, and pancreatic juice for 1, 3, and 7 days. Polydioxanone and Polypropylene showed stable values of UTS and E0-3 in all conditions. Polyglactin 910 presented significant UTS and E0-3 variations between different time intervals in all types of liquids analyzed. Poliglecaprone 25 lost half of its strength in all biological liquids analyzed but maintained low E0-3 values, which could reduce the risk of lacerations of soft tissues. These results suggest that Polydioxanone and Poliglecaprone 25 could be the best suture materials to use for pancreatic anastomoses. In vivo experiments will be organized to obtain further confirmations of this in vitro evidence.

Nanostructured Polyacrylamide Hydrogels with Improved Mechanical Properties and Antimicrobial Behavior.

This work proposes a simple method to obtain nanostructured hydrogels with improved mechanical characteristics and relevant antibacterial behavior for applications in articular cartilage regeneration and repair. Low amounts of silver-decorated carbon-nanotubes (Ag@CNTs) were used as reinforcing agents of the semi-interpenetrating polymer network, consisting of linear polyacrylamide (PAAm) embedded in a PAAm-methylene-bis-acrylamide (MBA) hydrogel. The rational design of the materials considered a specific purpose for each employed species: (1) the classical PAAm-MBA network provides the backbone of the materials; (2) the linear PAAm (i) aids the dispersion of the nanospecies, ensuring the systems’ homogeneity and (ii) enhances the mechanical properties of the materials with regard to resilience at repeated compressions and ultimate compression stress, as shown by the specific mechanical tests; and (3) the Ag@CNTs (i) reinforce the materials, making them more robust, and (ii) imprint antimicrobial characteristics on the obtained scaffolds. The tests also showed that the obtained materials are stable, exhibiting little degradation after 4 weeks of incubation in phosphate-buffered saline. Furthermore, as revealed by micro-computed tomography, the morphometric features of the scaffolds are adequate for applications in the field of articular tissue regeneration and repair.

INVESTIGATION OF BIODEGRADATION AND PROPERTIES OF POLYURETHANE FOAM COMPOSITE MATERIALS WITH LYSOZYME IN VITRO

The study of biodegradation ability of polyurethane foams composite materials with lysozyme under the influence of saline solution for 2 weeks, 1, 3 and 6 months by IR spectroscopy, DSC, TGA was conducted. According to the results of IR spectroscopy under the influence of model medium there are processes of biodegradation, which are confirmed by a decrease in the intensity of the absorption band νС=О. Along with biodegradation there is a redistribution of hydrogen bonds of NH and CO groups of polymer matrix. According to DSC after incubation in saline solution there is an increase in Tg and ΔCp at the glass-transition (for polyurethane foams and composites with lysozyme in the amount of 5 wt. %), an increase in Tg and decrease in ΔCp (for composites with lysozyme in the amount of 1 and 3 wt. %), which indicates the redistribution of hydrogen bonds under the influence of saline solution and due to lysozyme release. It was found that after incubation in saline solution there is an increase in T0 and Tmax for both polyurethane foams and composite materials with lysozyme by the method of TGA. Thus, composites with lysozyme in vitro are heat-resistant materials. According to the study results of the dynamics of lysozyme release composites are capable to the prolonged release of enzyme for 5 days, the amount of which varies depending on the lysozyme content (43.85-61.97 % of the total amount of the introduced drug) and is sufficient for the manifestation of antimicrobial activity. The tissue culture method has established the biocompatibility of investigated materials. For polyurethane foam composite materials with lysozyme more active growth of fibroblastic elements than in the control and polyurethane foam and slowing down the process of cell degeneration was observed. The obtained results indicate that polyurethane foam composite materials with lysozyme are promising materials that due to the presence of the enzyme will have antimicrobial action and can be used in medical practice as polymer composites for the treatment of wounds and burns.

Influences of the priming procedure and saline circulation conditions on polyvinylpyrrolidone in vitro elution from polysulfone membrane dialyzers

In hemodialysis (HD), the patient's blood is purified via circulation in an extracorporeal circuit containing a dialyzer. In the manufacturing process of polysulfone (PSu) membrane dialyzers, the membranes are hydrophilized via the addition of the hydrophilic agent polyvinylpyrrolidone (PVP) to increase their hydraulic permeability. The elution of PVP from the membrane reduces the membrane's hydraulic permeability, and the eluted PVP could cause adverse effects in the human body. Therefore, it is important to identify the factors that induce PVP elution from PSu dialyzer membranes to improve the efficiency and safety of HD. In the present study, experimental circuits connecting each of the three types of PSu membrane dialyzers that had been sterilized, using gamma irradiation, autoclaving, or in-line steam methods, were prepared. After the dialyzers were primed, saline was circulated in the circuits at a flow rate of 100 mL/min or 200 mL/min. At 0, 2, 4, 6, and 8 h after circulation was initiated, the amount of PVP eluted from the PSu membranes in vitro was determined. In this experimental setting, longer the circulation duration, greater the amount of PVP eluted from the PSu membranes of the tested dialyzers; however, the flow rate did not influence the in vitro elution of PVP. Furthermore, the immersion of the dialyzer membranes in saline for 24 h strongly facilitated the in vitro elution of PVP. In sum, these results suggest that the duration of PSu membrane incubation in saline is a determinant of the level of PVP elution from the PSu membrane dialyzers.

Route of administration affects the efficacy of moxidectin against Ostertagiinae nematodes in farmed red deer (Cervus elaphus)

The influence of route of administration on the pharmacokinetics and efficacy of macrocyclic lactone anthelmintics has been a subject of interest due to its potential to influence the development of anthelmintic resistance. For most parasite species studied so far, oral administration results in the highest concentrations of drug in the parasites and the highest efficacy against resistant genotypes. However, a recent study in cattle measured the highest levels of ivermectin in the abomasal Ostertagia ostertagi following subcutaneous injection, but it was not possible to correlate these elevated levels with efficacy. Therefore, the current study was initiated to determine whether injectable delivery might be optimal for attaining high efficacy against this important group of parasites.Three on-farm trials were conducted to measure the efficacy of moxidectin administered by the oral, injectable, and pour-on routes against Ostertagiinae parasites in farmed red deer. Groups of rising 1-year old stags (red or red-wapiti crossbreds) in the 84−104 kg weight range were randomised on liveweight into treatment groups of 6 (1 farm) or 8 (2 farms). Animals were treated to individual liveweight with moxidectin oral (0.2 mg/kg), injectable (0.2 mg/kg), pour-on (0.5 mg/kg) or remained untreated. Twelve days later all animals were euthanised and abomasa recovered for worm count. Adult worms were counted in a 2% aliquot of abomasal washings, and adult and fourth stage larvae in a 10 % aliquot following mucosal incubation in physiological saline. In addition, blood was collected from the same 5 animals in each of the treatment groups on days 0, 1, 2, 3, 5, 7 and 12 after treatment and moxidectin levels in plasma were determined using a mass spectrometer.The number of Ostertagiinae surviving treatment was significantly different for each of the treatment groups with injectable administration being most effective, oral administration being the next most effective and pour-on administration the least effective. This applied to both adult worms and fourth stage larvae. A similar pattern was seen in the levels of moxidectin in plasma with both the peak value and area under the concentration curve being highest following injectable administration and lowest following pour-on treatment.Although undertaken in a different host species, the results support the proposition that injectable administration of macrocyclic lactone anthelmintics is likely to be optimal for efficacy against Ostertagiinae parasites and potentially useful in slowing the emergence of resistance in these parasites.

Silica-filled methacrylic composites with extremely high compressive strength

SYLOID® 244 has never been applied as a filler in composites with potential dental application. Therefore, the aim of research was to apply this silica in its unmodified and diazonium salt-modified forms in different mass ratios as fillers in light-cured methacrylic composites. The effectiveness of modification process was confirmed with the use of Raman spectroscopy. Methacrylic composites with the modified and unmodified SYLOID® 244, as well as unfilled resin as a control group were prepared. Their basic physicochemical properties, such as depth of cure, mass stability during incubation in saline, flexural and compressive strengths were examined. A positive effect of SYLOID® 244 modification on the properties of the examined composites was also demonstrated. The obtained results proved the high applicability of SYLOID® 244 as a filler in composites with potential dental applications.

Comparison of some immunological parameters between untreated and ivermectin-treated onchocerciasis patients in the Nkwanta North District of Ghana

Background: Onchocerciasis (river blindness) is a neglected tropical disease that affects the skin and the eye. It is caused by a nematode parasite, Onchocerca volvulus. The disease pathology is largely attributed to host immune responses to the microfilariae. The efficacy of ivermectin (IVM) is defined by its microfilaricidal effects (clearing >60% of microfilariae within 24 h, ∼100% within 7 days) and its ability to temporarily retard the embryogenesis of the adult female parasite at least within 90 days. We sought to profile and compare immune parameters of untreated microfilaremic and IVM-treated amicrofilaremic onchocerciasis patients to identify immune factors differentially associated with microfilaremia. This will help understand the disease mechanism. Methods & Materials: Four bloodless skin biopsies were taken from the two iliac crests and two calves using the corneoscleral punch. The microfilariae emerging from the skin biopsies following overnight incubation in physiological saline in 96-well plate was quantified under the inverted light microscope. We measured white blood cell differentials for 124 adults; 53 microfilaremic (MF) and 71 ivermectin treated (1–5 rounds) seropositive amicrofilaremic (AMF) individuals 3 months following last treatment at the Nkwanta North District of Ghana. Subgroups (16 ≤ n ≤ 20) of both MF and first-time IVM-treated AMF were assayed for plasma cytokines, total serum IgE and urine histamine. Comparisons were made by Mann-Whitney U tests. Results: The geometric mean microfilariae density/milligram skin snip was 22.5 (range 5.8–56.3). Basophil count was lower (p < 0.0001) while eosinophil counts were higher (p = 0.02) for MF compared to AMF. Out of 14 cytokines (IL-1β, IL-2, IL-4, IL-5, IL-6, IL-7, IL-8, IL-10, IL-12, IL-13, IFN-γ, TNF-α, GM-CSF and TGFβ); three, Interleukin (IL)-13 (p = 0.002), IL-8 (p = 0.03) and Interferon-gamma (p = 0.003) were higher among MF compared to first time IVM-treated AMF. Histamine and IgE were not different between the two groups. Conclusion: IL-13, IL-8 and interferon-gamma, basophils and eosinophils differentiated between untreated and treated patients and hence these immune parameters might be contributing to the disease pathophysiology among microfilaremic onchocerciasis patients in the Nkwanta North District of Ghana.

Conditionally essential genes for survival during starvation in Enterococcus faecium E745

BackgroundThe nosocomial pathogen Enterococcus faecium can survive for prolonged periods of time on surfaces in the absence of nutrients. This trait is thought to contribute to the ability of E. faecium to spread among patients in hospitals. There is currently a lack of data on the mechanisms that are responsible for the ability of E. faecium to survive in the absence of nutrients.ResultsWe performed a high-throughput transposon mutant library screening (Tn-seq) to identify genes that have a role in long-term survival during incubation in phosphate-buffered saline (PBS) at 20 °C. A total of 24 genes were identified by Tn-seq to contribute to survival in PBS, with functions associated with the general stress response, DNA repair, metabolism, and membrane homeostasis. The gene which was quantitatively most important for survival in PBS was usp (locus tag: EfmE745_02439), which is predicted to encode a 17.4 kDa universal stress protein. After generating a targeted deletion mutant in usp, we were able to confirm that usp significantly contributes to survival in PBS and this defect was restored by in trans complementation. The usp gene is present in 99% of a set of 1644 E. faecium genomes that collectively span the diversity of the species.ConclusionsWe postulate that usp is a key determinant for the remarkable environmental robustness of E. faecium. Further mechanistic studies into usp and other genes identified in this study may shed further light on the mechanisms by which E. faecium can survive in the absence of nutrients for prolonged periods of time.

Surface display of p75, a\xa0Lactobacillus rhamnosus GG derived protein, on Bacillus subtilis spores and its antibacterial activity against Listeria monocytogenes

Lactobacillus rhamnosus p75 protein with peptidoglycan hydrolase (PGH) activity is one of the key molecules exhibiting anti-apoptotic and cell-protective activity for human intestinal epithelial cells. In this study, with the goal of developing new probiotics, the p75 protein was displayed on the surface of Bacillus subtilis spores using spore coat protein CotG as an anchoring motif. The PGH activity, stability, and the antibacterial activity of the spore-displayed p75 (CotG-p75) protein were also investigated. The PGH activity of the CotG-p75 against peptidoglycan extracted from B. subtilis was confirmed by the ninhydrin test. Under various harsh conditions, compared to the control groups, the PGH activities of CotG-p75 were very stable in the range of pH 3–7 and maintained at 70% at 50 °C. In addition, the antibacterial activity of CotG-p75 against Listeria monocytogenes was evaluated by a time-kill assay. After 6 h incubation in phosphate-buffered saline, CotG-p75 reduced the number of viable cells of L. monocytogenes by up to 2.0 log. Scanning electron microscopy analysis showed that the cell wall of L. monocytogenes was partially damaged by the treatment with CotG-p75. Our preliminary results show that CotG-p75 could be a good candidate for further research to develop new genetically engineered probiotics.

Time-Transient Effects of Silver and Copper in the Porous Titanium Dioxide Layer on Antibacterial Properties.

Recently, silver (Ag) and copper (Cu) have been incorporated into a titanium (Ti) surface to realize their antibacterial property. This study investigated both the durability of the antibacterial effect and the surface change of the Ag- and Cu-incorporated porous titanium dioxide (TiO2) layer. Ag- and Cu-incorporated TiO2 layers were formed by micro-arc oxidation (MAO) treatment using the electrolyte with Ag and Cu ions. Ag- and Cu-incorporated specimens were incubated in saline during a period of 0–28 days. The changes in both the concentrations and chemical states of the Ag and Cu were characterized using X-ray photoelectron spectroscopy (XPS). The durability of the antibacterial effects against Escherichia coli (E. coli) were evaluated by the international organization for standardization (ISO) method. As a result, the Ag- and Cu-incorporated porous TiO2 layers were formed on a Ti surface by MAO. The chemical state of Ag changed from Ag2O to metallic Ag, whilst that of Cu did not change by incubation in saline for up to 28 days. Cu existed as a stable Cu2O compound in the TiO2 layer during the 28 days of incubation in saline. The concentrations of Ag and Cu were dramatically decreased by incubation for up to 7 days, and remained a slight amount until 28 days. The antibacterial effect of Ag-incorporated specimens diminished, and that of Cu was maintained even after incubation in saline. Our study suggests the importance of the time-transient effects of Ag and Cu on develop their antibacterial effects.

Nanocomposites from functionalized bacterial cellulose and poly(3-hydroxybutyrate-co-3-hydroxyvalerate)

Bacterial cellulose (BC) sponges are valuable materials for tissue engineering and regenerative medicine due to their biocompatibility and nano-sized fibrous network with interconnected open porosity. However, their instability in physiological environment and poor mechanical properties are the main issues that need to be solved in order to obtain appropriate three-dimensional scaffolds for tissue formation. In this work, a bacterial polyester, poly (3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV) and a simple impregnation method were used to improve the properties of BC sponges for biomedical application. Highly hydrophilic BC was surface functionalized by amination (BCA) to improve its affinity to PHBV. PHBV uptake in BC and BCA sponges depended on the PHBV concentration and was confirmed by Fourier transform infrared spectroscopy and by the increase in density after impregnation. SEM investigation showed that PHBV was deposited on the BC nanofibrous network, in some conditions forming a tridimensional honeycomb ordered structure with uniform micrometer pores. Thermogravimetric and kinetic analyses showed a delay in the thermal degradation for the BCA nanocomposites sponges compared to the BC ones and an increase in the activation energy of degradation compared to neat PHBV. Better compression strength was obtained for BCA/PHBV nanocomposite sponges due to the increased interactions between the polymer and the aminated cellulose substrate. Swelling tests showed that BC and BCA sponges did not resist and completely disintegrated in 90 min of incubation in phosphate-buffered saline, but a good stability in this simulated physiological environment was obtained after impregnation with PHBV. The swelling degree varied between 1200% and 2400% for BC/PHBV and between 700% and 1200% for BCA/PHBV sponges, which are high enough to allow the diffusion of water and the transport of nutrients. Therefore, these easily obtained BC/PHBV and BCA/PHBV nanocomposite sponges, with improved properties, could be a promising option for tissue engineering scaffolds.

Calcium-Rich 13X Zeolite as a Filler with Remineralizing Potential for Dental Composites.

A zeolite with high ion-exchange potential was used as an active filler with remineralizing potential in composites that can be applied in restorative dentistry. Two calcium-rich forms of the 13X zeolite were obtained by sodium to calcium ion exchange and mineralization of a hydroxyapatite layer. These fillers were also silanized and mixed with methacrylic resins and photoinitiators to obtain composite materials. First, the effectiveness of the filler preparation and silanization was confirmed by X-ray diffractometry, scanning electron microscopy, energy dispersive spectroscopy, transmission electron microscopy, nitrogen adsorption/desorption measurements, thermogravimetric analysis, and Fourier transform infrared spectroscopy. The physicochemical characteristics of composites with silanized and nonsilanized forms of sodium- and calcium-rich 13X zeolite fillers were examined. The degree of conversion, depth of cure, flexural and compressive strength, mass stability, and remineralizing potential, understood as the ability to release calcium ions in the conditions simulating a natural oral environment, were determined. The effect of ion exchange, hydroxyapatite mineralization, and silanization of fillers on the final composites' properties was examined. Composites with calcium-rich fillers proved to show the ability to release Ca2+ during incubation in saline for 14 days at 36.6 °C showing therefore remineralizing potential with good values of other parameters.

Adhesive Submucosal Injection Material Based on the Nonanal Group-Modified Poly(vinyl alcohol)/α-Cyclodextrin Inclusion Complex for Endoscopic Submucosal Dissection.

Complete resection of early-stage cancer and subsequent wound care of the resection site are both important factors for successful endoscopic submucosal dissection (ESD). Although many submucosal injection materials (SIMs) have been developed to lift up lesions and completely remove cancers, a lack of materials with multiple functions, such as stable submucosal cushion formation, emergency perforation closure, and blood coagulation and wound sealing abilities, still exists. In this study, an adhesive submucosal injection material based on nonanal group-modified poly(vinyl alcohol) (C9-PVA) and α-cyclodextrin (α-CD) was developed to solve clinical problems associated with ESD. Focusing on the inclusion ability of α-CD for alkyl groups, a water-soluble α-CD/C9-PVA inclusion complex (IC) was prepared using water-insoluble C9-PVA in aqueous solutions. The IC of 2.5 mol % nonanal group-modified PVA (2.5C9-PVA), with 53 mM α-CD, showed good gel-sol reversibility and high injectability. Additionally, the α-CD/2.5C9-PVA IC performed well at submucosal cushion formation, with the increased height reaching 5.90 ± 0.38 mm. The complex also adhered well to the submucosa, successfully sealing wounds for over 7 days even in an aqueous environment. Furthermore, following incubation in physiological saline (1.80 ± 0.37 kPa), the burst strength of the α-CD/2.5C9-PVA IC was 1.5-fold higher compared with that of the commercial fibrin sealant, illustrating the possibility of emergency perforation closure. Finally, the complex promoted blood coagulation when mixed with fresh porcine whole blood. These results indicate that the multifunctional α-CD/2.5C9-PVA IC could be an ideal material for ESD.

Three-Dimensional Extrusion Printing of Porous Scaffolds Using Storable Ceramic Inks.

In this study, we describe the additive manufacturing of porous three-dimensionally (3D) printed ceramic scaffolds prepared with hydroxyapatite (HA), β-tricalcium phosphate (β-TCP), or the combination of both with an extrusion-based process. The scaffolds were printed using a novel ceramic-based ink with reproducible printability and storability properties. After sintering at 1200°C, the scaffolds were characterized in terms of structure, mechanical properties, and dissolution in aqueous medium. Microcomputed tomography and scanning electron microscopy analyses revealed that the structure of the scaffolds, and more specifically, pore size, porosity, and isotropic dimensions were not significantly affected by the sintering process, resulting in scaffolds that closely replicate the original dimensions of the 3D model design. The mechanical properties of the sintered scaffolds were in the range of human trabecular bone for all compositions. All ceramic bioinks showed consistent printability over a span of 14 days, demonstrating the short-term storability of the formulations. Finally, the mass loss did not vary among the evaluated compositions over a period of 28 days except in the case of β-TCP scaffolds, in which the structural integrity was significantly affected after 28 days of incubation in phosphate-buffered saline. In conclusion, this study demonstrates the development of storable ceramic inks for the 3D printing of scaffolds of HA, β-TCP, and mixtures thereof with high fidelity and low shrinkage following sintering that could potentially be used for bone tissue engineering in load-bearing applications.

Preparation of calcium phosphate/carboxymethylcellulose-based bone cements

In this study, novel bone substitutes were prepared based on a powder phase composed of tetracalcium phosphate, dicalcium phosphate dihydrate and calcium sulfate dihydrate and a liquid phase composed of carboxymethylcellulose (CMC), citric acid and gelatin. Samples were characterized by Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), X-ray diffraction (XRD), mechanical testing, swelling–degradation studies and cell culture studies. FTIR results showed that CMC and calcium phosphate interacted through electrostatic forces and hydrogen bonding. After incubation in phosphate-buffered saline for 28 days, hydroxyapatite formation was distinguished by way of SEM and XRD analysis. Mechanical test results revealed that the compressive modulus was up to 1.050 ± 0.071 GPa and that the compressive strength was up to 1.680 ± 0.023 MPa. Cell culture studies indicated that the samples were biocompatible and may be suitable for replacing cancellous bone and supporting new bone formation.

Chemical manipulations to facilitate membrane blebbing and vesicle shedding on the cellular cortex.

Most attention has been focused on physiologically generated membrane blebs on the cellular cortex, whereas artificial membrane blebs induced by chemicals are studied to a lesser extent. We found that exposure of HeLa human cervical cancer cells to paraformaldehyde (PFA), followed by incubation in phosphate-buffered saline (PBS) efficiently induced large membrane blebs on the cellular cortex. Intriguingly, sequential exposure of the PFA-treated cells to PBS containing dimethyl sulfoxide (DMSO) facilitated shedding of the blebs from the cellular cortex, yielding a high quantity of large extracellular vesicles in the supernatant, which was applicable to assess the potentials of compounds and proteins as membrane influencers. Similar effects of PFA and DMSO were detected on the cellular cortex of other human, mouse, and fish cells. Our procedure to facilitate membrane blebbing and vesicle shedding by chemicals may be practical for the manipulation of membrane dynamics and the development of vesicle-inspired technologies using a wide variety of cell types.