Silver Nanoparticles Alone or in Combination with Calcium Hydroxide Modulate the Viability, Attachment, Migration, and Osteogenic Differentiation of Human Mesenchymal Stem Cells.

This study aimed to evaluate the effect of silver nanoparticles (AgNPs) alone or in combination with calcium hydroxide (Ca(OH)2) on the proliferation, viability, attachment, migration, and osteogenic differentiation of human mesenchymal stem cells (hMSCs). Different concentrations of AgNPs alone or mixed with Ca(OH)2 were prepared. Cell proliferation was measured using AlamarBlue, and hMSCs attachment to dentin disks was evaluated using scanning electron microscopy. Live-dead imaging was performed to assess apoptosis. Wound healing ability was determined using the scratch-migration assay. To evaluate osteogenic differentiation, the expression of Runt-related transcription factor (RUNX2), Transforming growth factor beta-1 (TGF-ß1), Alkaline Phosphatase (ALP), and Osteocalcin (OCN) were measured using real-time reverse transcriptase polymerase chain reaction. ALP staining and activity were also performed as indicators of osteogenic differentiation. AgNPs alone seemed to favor cell attachment. Lower concentrations of AgNPs enhanced cell proliferation. AgNP groups showed markedly less apoptosis. None of the medicaments had adverse effects on wound closure. The expression of TGF-ß1 was significantly upregulated in all groups, and OCN was highly expressed in the AgNP groups. AgNPs 0.06% showed the most enhanced ALP gene expression levels, activity, and marked cytochemical staining. In conclusion, AgNPs positively affect hMSCs, making them a potential biomaterial for various clinical applications.

Bioaggregate of photo-fermentative bacteria for enhancing continuous hydrogen production in a sequencing batch photobioreactor.

Hydrogen recovery through solar-driven biomass conversion by photo-fermentative bacteria (PFB) has been regarded as a promising way for sustainable energy production. However, a considerable fraction of organic substrate was consumed for the growth of PFB as biocatalysts, furthermore, these PFB were continuously washed out from the photobioreactor in continuous operation because of their poor flocculation. In this work, PFB bioaggregate induced by L-cysteine was applied in a sequencing batch photobioreactor to enhance continuous hydrogen production and reduce biomass washout. The effects of the hydraulic retention time (HRT), influent concentration and light intensity on hydrogen production of the photobioreactor were investigated. The maximum hydrogen yield (3.35 mol H2/mol acetate) and production rate (1044 ml/l/d) were obtained at the HRT of 96 h, influent concentration of 3.84 g COD/l, and light intensity of 200 W/m(2). With excellent settling ability, biomass accumulated in the photobioreactor and reached 2.15 g/l under the optimum conditions. Structural analysis of bioaggregate showed that bacterial cells were covered and tightly linked together by extracellular polymeric substances, and formed a stable structure. Therefore, PFB bioaggregate induced by L-cysteine is an efficient strategy to improve biomass retention capacity of the photobioreactor and enhance hydrogen recovery efficiency from organic wastes.

Modeling the kinetics of calcium hydroxide catalyzed methanolysis of sunflower oil.

The kinetics of Ca(OH)(2)-catalyzed methanolysis of sunflower oil was studied at a moderate temperature (60 degrees C), a methanol-to-oil molar ratio (6:1) and different catalyst amounts (from 1% to 10% based on oil weight). The methanolysis process was shown to involve the initial triglyceride (TG) mass transfer controlled region, followed by the chemical reaction controlled region in the latter period. The TG mass transfer limitation was caused by the low available active specific catalyst surface due to the high adsorbed methanol concentration. Both the TG mass transfer and chemical reaction rates increased with increasing the catalyst amount.

Dynein cleavage and microtubule accumulation in okadaic acid-treated neurons.

Impairment of protein phosphatase 2A (PP2A) activity is implicated in tau hyperphosphorylation and microtubule (MT) instability in Alzheimer's disease (AD). Here, we report that okadaic acid, an effective PP2A inhibitor, suppresses the levels of acetylated and detyrosinated tubulins, but enhances tyrosinated tubulins in rat primary cortical neuron cultures. Immunocytochemistry experiments reveal that MTs accumulate intensely around soma and proximal neurites, implying impairment of MT transport to distal neurites which is mediated by dynein and dynactin. Here, we reveal that they can be cleaved by calpain. Notably, shortening of process length in OA-treated neurons is alleviated when calpain cleavage activity is inhibited. Based on these results, we propose that calpain-mediated dynein cleavage in OA-treated neurons is responsible for the MT transport deficit, and consequently, neurite retraction.

Effect of calcium hydroxide and chlorhexidine based gutta-percha points on gingival fibroblasts and epithelial tumor cells.

AIMS AND METHODS: The aim of the present study was to demonstrate the possible effect of different endodontic calcium hydroxide and chlorhexidine-based gutta-percha points, on two different human cell culture systems. Two different calcium hydroxide (Roeko, Langenau, Germany) and one chlorhexidine (Activ Point/Roeko, Langenau, Germany) gutta-percha points were tested with gingival fibroblasts and epithelial tumor cells over a period of six days (n = 12). Conventional gutta-percha points (VDW, Munich, Germany) and cells that were not exposed to any substances served as controls (n = 12). Study parameters included cell vitality, cell count, protein synthesis and cell proliferation. RESULTS: All tested materials induced cell growth specific alterations. Chlorhexidine-based gutta-percha points showed a significant lower protein synthesis with both, gingival fibroblasts (0.013 +/- 0.009 mg/ml) and epithelial tumor cells (0.07 +/- 0.039 mg/ml), when compared with the controls (p > 0.05). Protein synthesis increase of the epithelial tumor cells (0.581 +/- 0.013 mg/ml, control) was observed with the conventional gutta-percha points (0.688 +/- 0.078 mg/ml) and with both gutta-percha points containing different calcium hydroxide-based formulations (0.776 +/- 0.115 and 0.7 +/- 0.047 mg/ ml). CONCLUSIONS: Under the conditions of this study, chlorhexidine containing gutta-percha points showed the highest effect on cell growth inhibition. No significant differences were observed between the tested material and the two different cell culture types.

Mast cells in tissue response to dentistry materials: an adhesive resin, a calcium hydroxide and a glass ionomer cement.

Synthetic materials used in dentistry may trigger various inflammatory responses. In order to evaluate biocompatibility, standardized implants of Calcium Hydroxide (CH), Glass Ionomer Cement (GIC) and Light-activated Dental Adhesive (LDA) were surgically introduced into Wistar rats' back bone. Six (experimental) animal groups, five each, and two Sham (S) groups were studied after 15 and 30 days from surgery. In each animal, the density of mast cells and interstitial fibrosis volume was evaluated by quantitative light microscopy. In addition, the interaction between the disk material and its fibrous capsule was evaluated by scanning electron microscopy. The density of mast cells per area (N(A)[mast cells]) was lower in CH group than in LDA group. GIC group displayed N(A)[mast cells] results intermediate between CH and LDA groups (p<0.05). The smallest interstitial fibrosis volume density (Vv[f]) was observed in CH group, then in GIC group, while the greatest in LDA group. After 30 days, the fibrosis in LDA group was 30% higher than in CH group (p<0.05). In S group, discreet fibrosis restricted to surgical area was present, with few mast cells near the vessels. Significant interaction between fibrous capsule and the surrounding disk material was most evident in CH group. The implanted materials induced mast cell migration, distinct fibrosis development, suggesting that CH is the most biocompatible material among those tested.

[Prophylactic and therapeutic effect of oxymatrine on D-galactosamine-induced rat liver fibrosis].

OBJECTIVE: To investigate the prophylactic and therapeutic effect of oxymatrine on experimental liver fibrosis and to reveal its mechanism. METHODS: By establishing D-galactosamine-induced rat liver fibrosis model, we observed the effect of oxymatrine on serum and tissue biochemical indexes, content of liver hydroxyline, expression of TGF?1 mRNA and changes of tissue pathology. RESULTS: There was a decline of liver hydroxyline and serum AST and ALT in oxymatrine group compared to those of the D-GalN group. The hydroxyline content in oxymatrine pretreatment group was (0.50 0.11)mug/mg compared with (0.99 0.14)mug/mg in D-GalN group (t=8.366, P<0.01). The content in oxymatrine treatment group was (0.44 0.04)mug/mg compared with 0.70 0.06 in D-GalN group (t=9.839, P<0.01). The SOD activity was (149.81 15.28) NU/mg in oxymatrine pretreatment group and (95.22 16.33) NU/mg in the model group (t=7.309, P<0.01); (157.68 19.54) NU/mg in the treatment group compared with (119.88 14.94) NU/mg in the model group (t=4.348, P<0.01). MDA in the pretreatment group was (2.06 0.17) nmol/mg, lower than (4.57 0.37) nmol/mg in the model group (t=17.529, P<0.01). In the treatment group, it was (1.76 0.24)nmol/mg, lower than (3.10 0.17) nmol/mg in the model group (t=12.697, P<0.01). TGF?1 mRNA reduced in the pretreatment and treatment groups as compared with that in the model group (0.21 0.01 vs 0.50 0.01, t=48.665, P<0.01; 0.18 0.02 vs 0.38 0.01, t=22.464, P<0.01). Electron microscopy showed that oxymatrine group had milder hepatocyte degeneration and less fibrosis accumulation than did the model group. Microscopy revealed wide septa expansion from the portal area to the central venous, piecemeal and confluent necrosis and pseudo-nodular formation in part of the lobular in the model group. While in oxymatrine group these lesions were much improved. CONCLUSIONS: Oxymatrine shows prophylactic and therapeutic effect in D-galactosamine induced rat liver fibrosis. This is partly by protecting hepatocyte and suppressing fibrosis accumulation through anti-lipoperoxidation.

Role of lime in the generation of reactive oxygen species from betel-quid ingredients.

The role of lime in the formation of reactive oxygen species (ROS), i.e., O2-., H2O2, and OH., from betel-quid components (extracts of areca nut and catechu) was investigated in vitro using a chemiluminescence technique and an assay for oxidative DNA damage involving analysis of 8-hydroxy-2'-deoxyguanosine. Of the various areca-nut extracts, the catechin fraction, at alkaline pH, was shown to be the most active producer of ROS. The free Ca(OH)2 content and pH of lime samples (a component of betel quid and chewing tobacco) were highly correlated with the generation of ROS from areca-nut extract in vitro and with oxidative base damage to DNA in vitro. While Fe2+ had an enhancing effect on ROS formation, Mg2+ had a marked inhibitory effect. The cytogenetic effects of ROS generated in vivo were measured in Syrian golden hamsters in which the cheek pouch had been painted with lime and an areca-nut extract or catechu, singly or in combination. The frequency of micronucleated cells was increased only in animals that had received both the areca-nut extract and lime. The frequency of micronucleated cells in exfoliated oral mucosal cells from Indian chewers of betel quid with tobacco containing lime or of tobacco with lime was significantly higher than in a control (no habit) group. These studies demonstrate that addition of lime to betel quid constituents generates ROS, which induce cytogenetic damage in hamster cheek pouch and may contribute to the cytogenetic damage observed in the oral cavity of betel-quid chewers. These results implicate ROS in clastogenesis and probably in the etiology of oral cancer.

Complexing of toxic hydrolysable tannins of yellow-wood (Terminalia oblongata) and harendong (Clidemia hirta) with reactive substances: an approach to preventing toxicity.

Ruminants consuming either tannic acid or hydrolysable tannins from the Australian yellow-wood tree (Terminalia oblongata) and the Indonesian shrub Clidemia hirta are intoxicated by simple phenolics liberated in the gut. The affinity of these tannins and of the simple phenolic gallic acid for the two proteins casein and pepsin, polyvinylpyrolidone (PVP), activated charcoal and Ca(OH)2 was examined in vitro. The studies were undertaken to predict the effect of these phenolics on digestion and to identify substances that would act as antidotes by precipitating phenolics. Tannins but not gallic acid were precipitated as stable complexes with both pepsin and casein at pH 3-5. Optimal complexing of tannin with protein occurred at a weight ratio of 1:1. Ionic strength and temperature did not affect the amount of tannin precipitated from solution with protein. The precipitation of tannins with PVP and Ca(OH)2 was unaffected by pH within the range 2-8 while maximum binding with activated charcoal occurred between pH 3 and 7. In contrast to protein, the other substances complexed with gallic acid; only gallic acid-PVP complexes were affected by pH. Calcium hydroxide bound more tannin and gallic acid on a weight basis than PVP and charcoal. Both Ca(OH)2 and activated charcoal should complex with phenolics in the forestomach, abomasum and intestines. The reaction of hydrolysable tannins and proteins at the pH found in the abomasum suggests that hydrolysable tannins would interfere with enzyme function and protein digestion post-ruminally rather than in the forestomach.

Tratamento de perfuraçöes radiculares com pastas de hidróxido de cálcio e iodofórmio: emprego de diferentes veículos; estudo histológico em dentes de cäes

Utilizando 40 pré-molares superiores e inferiores de cäes, os autores estudaram os efeitos de diferentes veículos para a pasta de hidróxido de cálcio no tratamento de perfuraçöes radiculares. Após os procedimentos endodônticos, realizou-se perfuraçöes na raiz mesial ao nivel e em direçäo à furca e os trajetos das perfuraçöes foram preenchidos com a pasta de hidróxido de cálcio e iodofórmio empregando-se como veículos, soro fisiológico, polietileno glicol e lipiodol U.F. O melhor resultado foi obtido quando se empregou o polietileno glicol como veículo para o hidróxido de cálcio