Premixed calcium silicate-based ceramic sealers promote osteogenic/cementogenic differentiation of human periodontal ligament stem cells: A microscopy study

To evaluate the effects of premixed calcium silicate based ceramic sealers on the viability and osteogenic/cementogenic differentiation of human periodontal ligament stem cells (hPDLSCs). The materials evaluated were TotalFill BC Sealer (TFbc), AH Plus Bioceramic Sealer (AHPbc), and Neosealer Flo (Neo). Standardized discs and 1:1, 1:2, and 1:4 eluates of the tested materials were prepared. The following in vitro experiments were carried out: ion release, cell metabolic activity 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay, cell migration, immunofluorescence experiment, cell attachment, gene expression, and mineralization assay. Statistical analyses were performed using one-way ANOVA followed by Tukey's post hoc test (p < .05). Increased Ca2+ release was detected in TFbc compared to AHPbc and Neo (*p < .05). Biological assays showed a discrete cell metabolic activity and cell migration in Neo-treated cell, whereas scanning electronic microscopy assay exhibited that TFbc group had a better cell adhesion process of substrate attachment, spreading, and cytoskeleton development on the niche-like structures of the cement than AHPbc and Neo. The sealers tested were able to induce overexpression of the CEMP-1, ALP, and COL1A1 genes in the first days of exposure, particularly in the case of TFbc (***p < .001). All materials tested significantly increased the mineralization of hPDLSCs when compared to the negative control, although more pronounced calcium deposition was observed in the TFbc-treated cells (***p < .001). Our results suggested that TFbc promotes cell differentiation, both by increasing the expression of key osteo/odontogenic genes and by promoting mineralization of the extracellular matrix, whereas this phenomenon was less evident in Neo and AHPbc. RESEARCH HIGHLIGHTS: TFbc group had a better cell adhesion process of substrate attachment, spreading, and cytoskeleton development on the niche-like structures of the cement than AHPbc and Neo. The sealers tested were able to induce overexpression of the CEMP-1, ALP, and COL1A1 genes in the first days of exposure, particularly in the case of TFbc. All materials tested significantly increased the mineralization of hPDLSCs when compared to the negative control, although more pronounced calcium deposition was observed in the TFbc-treated cells.

3D Graphene/silk fibroin scaffolds enhance dental pulp stem cell osteo/odontogenic differentiation

OBJECTIVES

The current in vitro study aims to evaluate silk fibroin with and without the addition of graphene as a potential scaffold material for regenerative endodontics.

MATERIAL AND METHODS

Silk fibroin (SF), Silk fibroin/graphene oxide (SF/GO) and silk fibroin coated with reduced graphene oxide (SF/rGO) scaffolds were prepared (n = 30). The microarchitectures and mechanical properties of scaffolds were evaluated using field emission scanning electron microscopy (FESEM), pore size and water uptake, attenuated total reflectance fourier transformed infrared spectroscopy (ATR-FTIR), Raman spectroscopy and mechanical compression tests. Next, the study analyzed the influence of these scaffolds on human dental pulp stem cell (hDPSC) viability, apoptosis or necrosis, cell adhesion, odontogenic differentiation marker expression and mineralized matrix deposition. The data were analyzed with ANOVA complemented with the Tukey post-hoc test (p < 0.005).

RESULTS

SEM analysis revealed abundant pores with a size greater than 50 nm on the surface of tested scaffolds, primarily between 50 nm and 600 µm. The average value of water uptake obtained in pure fibroin scaffolds was statistically higher than that of those containing GO or rGO (p < 0.05). ATR-FTIR evidenced that the secondary structures did not present differences between pure fibroin and fibroin coated with graphene oxide, with a similar infrared spectrum in all tested scaffolds. Raman spectroscopy showed a greater number of defects in the links in SF/rGO scaffolds due to the reduction of graphene. In addition, adequate mechanical properties were exhibited by the tested scaffolds. Regarding biological properties, hDPSCs attached to scaffolds were capable of proliferating at a rate similar to the control, without affecting their viability over time. A significant upregulation of ALP, ON and DSPP markers was observed with SF/rGO and SF/GO groups. Finally, SF/GO and SF/rGO promoted a significantly higher mineralization than the control at 21 days.

SIGNIFICANCE

Data obtained suggested that SF/GO and SF/rGO scaffolds promote hDPSC differentiation at a genetic level, increasing the expression of key osteo/odontogenic markers, and supports the mineralization of the extracellular matrix. However, results from this study are to be interpreted with caution, requiring further in vivo studies to confirm the potential of these scaffolds.

Effect of milled and lithography-based additively manufactured zirconia (3Y-TZP) on the biological properties of human osteoblasts

STATEMENT OF PROBLEM

Lithography-based additively manufactured (AM) zirconia has been used to fabricate dental implants and custom barriers for guided bone regeneration procedures. However, studies on the effect of AM zirconia on the biological properties of human osteoblasts are lacking.

PURPOSE

The purpose of this in vitro study was to compare the effect of milled and lithography-based AM zirconia on the biological properties of normal human osteoblasts (NHOsts), as well as to compare the chemical composition between the milled and lithography-based AM 3 mol% yttria-stabilized tetragonal zirconia polycrystal (3Y-TZP) zirconia.

MATERIAL AND METHODS

Three mol percentage yttria-stabilized tetragonal zirconia polycrystal disks (Ø6×2-mm) were fabricated using subtractive milling (Priti multidisc ZrO2 monochrome) (M group) and lithography-based additive manufacturing methods (LithaCon 3Y 210) (AM group) (n=10). NHOsts were exposed to different material extracts (1:1, 1:2, and 1:4) and cytotoxicity, cell migration, cell morphology, and cell attachment biological tests were completed. Additionally, for morphological and chemical analysis, a scanning electronic microscopy with energy-dispersive X-ray analysis (SEM/EDX) evaluation was completed. Data were analyzed by using 1-way ANOVA and the Dunnett test (α=.05).

RESULTS

Substantial cell attachment and spreading were observed in both material surfaces. The presence of zirconium was evident in both groups, although the percentage of zirconium in the AM group (64.7%) was slightly higher than in the M group (52.6%). When NHOsts were cultured in the presence of the different material eluates, the M and AM groups exhibited similar NHOst viability and migration rates when compared with untreated cells; no significant differences were found (P>.05).

CONCLUSIONS

The lithography-based AM zirconia tested showed adequate cytocompatibility without differences when compared with the milled zirconia (M group) specimens. Slight chemical element composition differences were found between milled and lithography-based AM zirconia.

Biological properties of Ceraputty as a retrograde filling material: an in vitro study on hPDLSCs

OBJECTIVES

To assess the cytocompatibility and bioactive potential of the new calcium silicate-based cement Ceraputty on human periodontal ligament stem cells (hPDLSCs) compared to Biodentine and Endosequence BC root repair material (ERRM).

MATERIALS AND METHODS

hPDLSCs were isolated from extracted third molars from healthy donors. Standardized sample discs and 1:1, 1:2, and 1:4 eluates of the tested materials were prepared. The following assays were performed: surface element distribution via SEM-EDX, cell attachment and morphology via SEM, cell viability via a MTT assay, osteo/cemento/odontogenic marker expression via RT-qPCR, and cell calcified nodule formation via Alizarin Red S staining. hPDLSCs cultured in unconditioned or osteogenic media were used as negative and positive control groups, respectively. Statistical analysis was performed using one-way ANOVA or two-way ANOVA and Tukey's post hoc test. Statistical significance was established at p < 0.05.

RESULTS

The highest Ca2+ peak was detected from Biodentine samples, followed by ERRM and Ceraputty. hPDLSC viability was significantly reduced in Ceraputty samples (p < 0.001), while 1:2 and 1:4 Biodentine and ERRM samples similar results to that of the negative control (p > 0.05). Biodentine and ERRM exhibited an upregulation of at least one cemento/odonto/osteogenic marker compared to the negative and positive control groups. Cells cultured with Biodentine produced a significantly higher calcified nodule formation than ERRM and Ceraputty (p < 0.001), which were also higher than the control groups (p < 0.001).

CONCLUSION

Ceraputty evidenced a reduced cytocompatibility towards hPDLSCs on its lowest dilutions compared to the other tested cements and the control group. Biodentine and ERRM promoted a significantly higher mineralization and osteo/cementogenic marker expression on hPDLSCs compared with Ceraputty. Further studies are necessary to verify the biological properties of this new material and its adequacy as a retrograde filling material.

CLINICAL RELEVANCE

This is the first study to elucidate the adequate biological properties of Ceraputty for its use as a retrograde filling material.

Are Endodontic Solvents Cytotoxic? An In Vitro Study on Human Periodontal Ligament Stem Cells

The aim of this study was to assess the influence of eucalyptol, chloroform, and Endosolv on the proliferative capability, cell viability, and migration rates of human periodontal ligament stem cells (hPDLSCs) in vitro. Solvent eluates were formulated following ISO 10993-5 guidelines, and 1%, 0.25%, and 0.1% dilutions were prepared. The HPDLSCs were isolated from the extracted third molars of healthy donors. The following parameters were assessed: cell viability via trypan blue and IC50 assays, cell migration via horizontal wound healing assay, cell morphology via cell cytoskeleton staining (phalloidin labeling), and cell oxidative stress via reactive oxygen species assay. The data were analyzed using one-way ANOVA and Tukey’s posthoc tests, and their significance was established at p < 0.05. Chloroform and eucalyptol exhibited significantly higher cytotoxicity on the hPDLSCs in vitro compared to the control group, as shown by the cell viability, migration, morphology, and reactive oxygen species release assays. Alternatively, Endosolv showed adequate cytotoxicity levels comparable to those of the control group. The cytotoxicity of the tested endodontic solvents increased in a dose-dependent manner. The results from the present study highlight the cytotoxicity of chloroform and eucalyptol. Thus, their limited and cautious use is recommended, avoiding solvent extrusion.

Dexamethasone and Doxycycline Doped Nanoparticles Increase the Differentiation Potential of Human Bone Marrow Stem Cells

Non-resorbable polymeric nanoparticles (NPs) are proposed as an adjunctive treatment for bone regenerative strategies. The present in vitro investigation aimed to evaluate the effect of the different prototypes of bioactive NPs loaded with zinc (Zn-NPs), doxycycline (Dox-NPs) or dexamethasone (Dex-NPs) on the viability, morphology, migration, adhesion, osteoblastic differentiation, and mineralization potential of human bone marrow stem cells (hBMMSCs). Cell viability, proliferation, and differentiation were assessed using a resaruzin-based assay, cell cycle analysis, cell migration evaluation, cell cytoskeleton staining analysis, Alizarin Red S staining, and expression of the osteogenic-related genes by a real-time quantitative polymerase chain reaction (RT-qPCR). One-Way ANOVA and Tukey’s test were employed. The resazurin assay showed adequate cell viability considering all concentrations and types of NPs at 24, 48, and 72 h of culture. The cell cycle analysis revealed a regular cell cycle profile at 0.1, 1, and 10 µg/mL, whereas 100 µg/mL produced an arrest of cells in the S phase. Cells cultured with 0.1 and 1 µg/mL NP concentrations showed a similar migration capacity to the untreated group. After 21 days, mineralization was increased by all the NPs prototypes. Dox-NPs and Dex-NPs produced a generalized up-regulation of the osteogenic-related genes. Dex-NPs and Dox-NPs exhibited excellent osteogenic potential and promoted hBMMSC differentiation. Future investigations, both in vitro and in vivo, are required to confirm the suitability of these NPs for their clinical application.

Interspecies Chimerism with Mammalian Pluripotent Stem Cells

Interspecies blastocyst complementation enables organ-specific enrichment of xenogenic pluripotent stem cell (PSC) derivatives. Here, we establish a versatile blastocyst complementation platform based on CRISPR-Cas9-mediated zygote genome editing and show enrichment of rat PSC-derivatives in several tissues of gene-edited organogenesis-disabled mice. Besides gaining insights into species evolution, embryogenesis, and human disease, interspecies blastocyst complementation might allow human organ generation in animals whose organ size, anatomy, and physiology are closer to humans. To date, however, whether human PSCs (hPSCs) can contribute to chimera formation in non-rodent species remains unknown. We systematically evaluate the chimeric competency of several types of hPSCs using a more diversified clade of mammals, the ungulates. We find that naïve hPSCs robustly engraft in both pig and cattle pre-implantation blastocysts but show limited contribution to post-implantation pig embryos. Instead, an intermediate hPSC type exhibits higher degree of chimerism and is able to generate differentiated progenies in post-implantation pig embryos.

Dietary habits of patients with schizophrenia: a self-reported questionnaire survey

The present study was carried out to determine the dietary habits of patients with schizophrenia and the influence of these habits on the degree of obesity. The study was developed in a sample of 159 patients, who were given a self-reported questionnaire, to ascertain the influence of socio-familiar aspects, pharmacological treatment, and dietary habits. Anthropometric measurements (body mass index (BMI) and waist circumference (WC)) were also taken. Patients with schizophrenia presented unhealthy dietary habits, as indicated by the finding that 51% of the patients took no longer than 15 min to eat, 40.8% did not eat fruit daily, and 63.1% did not eat fish. Women were three times more likely to be obese than men (odds ratio (OR) = 2.91, P = 0.021). Patients classified as having unhealthy dietary habits have a 2.33-fold higher risk of obesity than patients with good dietary habits (OR = 2.33, P = 0.034). In summary, this paper highlights the fact that patients with schizophrenia have a detrimental dietary pattern that is associated with an increase in BMI and WC, with the consequent development of obesity and related metabolic alterations, regardless of the pharmacological treatment being followed. Future research directions will include exploring the need for nutritional education programmes to improve the dietary habits of such patients.

A comparison of the membrane binding properties of C1B domains of PKCgamma, PKCdelta, and PKCepsilon

The C1 domains of classical and novel PKCs mediate their diacylglycerol-dependent translocation. Using fluorescence resonance energy transfer, we studied the contribution of different negatively charged phospholipids and diacylglycerols to membrane binding. Three different C1B domains of PKCs were studied (the classical gamma, and the novel delta and epsilon), together with different lipid mixtures containing three types of acidic phospholipids and three types of activating diacylglycerols. The results show that C1Bgamma and C1Bepsilon exhibit a higher affinity to bind to vesicles containing 1-palmitoyl-2-oleoyl-sn-phosphatidic acid, 1-palmitoyl-2-oleoyl-sn-phoshatidylserine, or 1-palmitoyl-2-oleoyl-sn-phosphatidylglycerol, with C1Bepsilon being the most relevant case because its affinity for POPA-containing vesicles increased by almost two orders of magnitude. When the effect of the diacylglycerol fatty acid composition on membrane binding was studied, the C1Bepsilon domain showed the highest binding affinity to membranes containing 1-stearoyl-oleoyl-sn-glycerol or 1,2-sn-dioleoylglycerol with POPA as the acidic phospholipid. Of the three diacylglycerols used in this study, 1,2-sn-dioleoylglycerol and 1-stearoyl-oleoyl-sn-glycerol showed the highest affinities for each isoenzyme, whereas 1,2-sn-dipalmitoylglycerol; showed the lowest affinity. DSC experiments showed this to be a consequence of the nonfluid conditions of 1,2-sn-dipalmitoylglycerol;-containing systems.

Interaction of the C2 Domain from Protein Kinase Cε with Model Membranes

The C2 domain from protein kinase Cepsilon (PKCepsilon) binds to membranes but does not require Ca2+ to do so. This work examines the mode in which the conformation and organization of the phospholipids present in model membranes are altered by the presence of the C2 domain from PKCepsilon (C2-PKCepsilon). It is concluded from the results of differential scanning calorimetry that the protein shifted the temperature of the gel to the fluid phase transition of pure 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphate (POPA), widening the transition and increasing it to a higher temperature. When POPA was mixed with 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine (POPC), the changes in the transition were smaller and no phase separation was observed. Experiments performed using magic angle spinning NMR showed that this C2 domain specifically affected POPA when the phospholipid was mixed with POPC, as indicated by the downfield shift in the isotropic resonance of POPA, the widening of the resonance peak, the decrease in T2, and the decrease in T1 observed at all temperatures. All these effects were quite marked compared with the very small effect observed with POPC, indicating the specificity of the effect. The presence of the C2-PKCepsilon protein changed the conformation of the polar head group of POPA, as shown by infrared spectroscopy. All these results clearly illustrate the electrostatic interaction that takes place between this C2 domain and membranes which contain POPA in the absence of Ca2+.

The C2 Domain of PKCα Is a Ca2+-dependent PtdIns(4,5)P2 Sensing Domain: A New Insight into an Old Pathway

The C2 domain is a targeting domain that responds to intracellular Ca2+ signals in classical protein kinases (PKCs) and mediates the translocation of its host protein to membranes. Recent studies have revealed a new motif in the C2 domain, named the lysine-rich cluster, that interacts with acidic phospholipids. The purpose of this work was to characterize the molecular mechanism by which PtdIns(4,5)P2 specifically interacts with this motif. Using a combination of isothermal titration calorimetry, fluorescence resonance energy transfer and time-lapse confocal microscopy, we show here that Ca2+ specifically binds to the Ca2+ -binding region, facilitating PtdIns(4,5)P2 access to the lysine-rich cluster. The magnitude of PtdIns(4,5)P2 binding is greater than in the case of other polyphosphate phosphatidylinositols. Very importantly, the residues involved in PtdIns(4,5)P2 binding are essential for the plasma membrane localization of PKCalpha when RBL-2H3 cells are stimulated through their IgE receptors. Additionally, CFP-PH and CFP-C1 domains were used as bioprobes to demonstrate the co-existence of PtdIns(4,5)P2 and diacylglycerol in the plasma membrane, and it was shown that although a fraction of PtdIns(4,5)P2 is hydrolyzed to generate diacylglycerol and IP3, an important amount still remains in the membrane where it is available to activate PKCalpha. These findings entail revision of the currently accepted model of PKCalpha recruitment to the membrane and its activation.

Structural study of the catalytic domain of PKCzeta using infrared spectroscopy and two-dimensional infrared correlation spectroscopy

The secondary structure of the catalytic domain from protein kinase C zeta was studied using IR spectroscopy. In the presence of the substrate MgATP, there was a significant change in the secondary structure. After heating to 80 degrees C, a 14% decrease in the alpha-helix component was observed, accompanied by a 6% decrease in the beta-pleated sheet; no change was observed in the large loops or in 3(10)-helix plus associated loops. The maximum increase with heating was observed in the aggregated beta-sheet component, with an increase of 14%. In the presence of MgATP, and compared with the sample heated in its absence, there was a substantial decrease in the 3(10)-helix plus associated loops and an increase in alpha-helix. Synchronous 2D-IR correlation showed that the main changes occurred at 1617 cm(-1), which was assigned to changes in the intermolecular aggregated beta-sheet of the denaturated protein. This increase was mainly correlated with the change in alpha-helix. In the presence of MgATP, the main correlation was between aggregated beta-sheet and the large loops component. The asynchronous 2D-correlation spectrum indicated that a number of components are transformed in intermolecularly aggregated beta-sheet, especially the alpha-helix and beta-sheet components. It is interesting that changes in 3(10)-helix plus associated loops and in alpha-helix preceded changes in large loops, which suggests that the open loops structure exists as an intermediate state during denaturation. In summary, IR spectroscopy revealed an important effect of MgATP on the secondary structure and on the thermal unfolding process when this was induced, whereas 2D-IR correlation spectroscopy allowed us to show the establishment of the denaturation pathway of this protein.

Cardiovascular disturbances caused by extradural negative pressure drainage systems after intracranial surgery

Extradural drainage systems connected to a vacuum device for preventing postoperative haematoma formation are often used in neurosurgical practice. Cardiovascular complications, including bradycardia or low arterial pressure caused by intracranial hypotension, have been described associated with their use. We have investigated the relationship between the negative pressure applied to extradural drainage systems and intracranial pressure (ICP), and analysed the effects of negative pressure of the drains on systolic (SAP), diastolic (DAP) and mean (MAP) arterial pressures and on heart rate (HR). We studied prospectively 15 patients undergoing neurosurgery for supratentorial tumours or aneurysms. Transient decreases in ICP (P < 0.001) and HR (P < 0.001), with no clinical effects, were observed after connecting the vacuum device to the drain. There were no significant changes in SAP, DAP or MAP.

[Pressure pneumocephalus after posterior fossa surgery in the sitting position]

Pneumocephalus occurs commonly soon after intracranial surgery. When it presents as a significant increase in intracranial pressure it is called pressure pneumocephalus, a severe, life-threatening complication of neurosurgery that requires immediate treatment. Tension pneumocephalus must be suspected in patients unexpectedly fail to awaken at the end of surgery or who present progressive neurological deterioration after posterior fossa surgery. Diagnosis is by computerized axial thomography of the brain. Treatment is simple, consisting of promptly releasing the pressurized gas by trephination to save the patient's life or prevent severe neurological sequelae. We report two cases of pressure pneumocephalus that illustrate several risk factors: sitting position during surgery, preoperative hydrocephaly, surgical opening of the fourth ventricular and the presence of cerebrospinal shunt during surgery.

[Effects of precurarization on oxygen arterial saturation measure with pulse oximetry and neuromuscular function]

OBJECTIVE

To study changes in arterial oxygen saturation (SpO2) measured by pulse oximetry, and the effect of neuromuscular function after precurarization with different nondepolarizing muscle relaxants.

PATIENTS AND METHOD

One hundred twenty-four patients scheduled for elective surgery were randomly assigned to four groups according to the NDPMR received: d-tubocurarine 0.05 mg/kg, atracurium 0.05 mg/kg, vecuronium 0.01 mg/kg or pancuronium 0.015 mg/kg. We recorded SpO2 before precurarization and 4 minutes after administering the dose. We also recorded signs and symptoms of muscle weakness after the 4-minute period of precurarization.

RESULTS

We observed a statistically significant decrease in SpO2 4 minutes after starting precurarization in the groups receiving pancuronium, vecuronium and atracurium. These three groups were also significantly different from the d-tubocurarine group with regard to signs and symptoms of muscle weakness; the incidences of such symptoms were similar among the three groups, the only exception being the greater difficulty patients in the pancuronium group had in maintaining the Valsalva maneuver for 10 seconds. The lowest incidence of clinical signs of muscle weakness were in the d-tubocurarine group. We found a significant relation between decreased SpO2 caused by precurarization and the variables of inability to maintain the Valsalva maneuver for 10 seconds and to raise the head for more than 4 seconds.

CONCLUSIONS

SpO2 measured by pulse oximetry is an effective method for monitoring breathing function in the precurarized patient, as it detects early changes in arterial oxygen saturation related to respiratory muscle weakness. The agent d-tubocurarine is recommended for precurarization, because of its scarce effect on neuromuscular function at the dose used in this study.