Ho-Yeon Song

Fabrication of polyvinyl alcohol/gelatin nanofiber composites and evaluation of their material properties

Electrospinning of polyvinyl alcohol (PVA), gelatin (GE), and a PVA/GE blend was conducted with the aim of fabricating biodegradable scaffolds for tissue engineering. The process parameters including the concentration of GE in PVA/GE blends, electrical field, and tip-to-collector distance (TCD) were investigated. Electrospinning processes were conducted at three different GE concentrations (PVA/GE = 2/8, 6/4, and 8/2), and the voltage and TCD were varied from 18 to 24 kV and 7 to 20 cm, respectively. The average diameter of the electrospun PVA, GE, and PVA/GE blend fibers ranged from 50 to 150 nm. The TCD had significant effects on the average diameter of the PVA/GE nanofiber, while changes in the voltage did not significantly affect the diameter of the PVA/GE nanofiber. The miscibility of the PVA/GE blend fibers was examined by differential scanning calorimetry, and X-ray diffraction was used to determine the crystallinity of the membrane. Tensile strength was measured to evaluate the physical properties of the membrane. Based on the combined results of this study, the PVA/GE membrane holds great promise for use in tissue engineering applications, especially in bone or drug delivery systems.

Nano Ag loaded PVA nano‐fibrous mats for skin applications

Silver nano-particles (Ag NPs) loaded polyvinyl alcohol (PVA) electro-spun fibers were fabricated using a combination of microwave-heated and electro-spinning methods for wound healing. A thermic process was then applied to resurface and increase the number of the Ag NPs on the surface of the PVA fiber. The diameter of the Ag NPs loaded electrospun PVA (PVA-Ag) mats were between 100 and 500 nm after heat treatments at different temperatures. When samples were subjected to 60 s of microwave irradiation and 150°C heat treatment, the maximum number of 50-100 nm Ag NPs resurfaced on the PVA nano-fiber. The nano mats significantly inhibited E. coli (gram-positive) and S. aureus (gram-negative) bacteria and displayed high mechanical stability (>45 MPa).

Protective effect of methylprednisolone on paraquat-induced A549 cell cytotoxicity via induction of efflux transporter, P-glycoprotein expression

Paraquat (PQ) is the third most extensively used herbicide in the world, causing thousands of deaths due to accidental or intentional self-poisoning in developing countries. Although many therapeutic treatments for PQ-induced poisonings have been proposed and developed, the efficacy of these treatments is still poor and requires further investigation. Methylprednisolone (trade name Solumedrol, hereinafter MP) is a widely used steroid for the treatment of various diseases but the function of MP has not yet been studied in the context of PQ-induced intoxication. The aim of this study was to determine if MP can ameliorate PQ-induced toxicity in an alveolar A549 cell line by inducing ATP-dependent transporter P-glycoprotein (P-gp) expression. P-gp expression and activity in the PQ-treated A549 cell line were enhanced by MP treatment and cytotoxicity by PQ was dramatically decreased. We also found that MP per se or together with PQ induced P-gp expression by both Western blot and qRT-PCR analyses. In addition, induced P-gp transporter was shown to improve the efflux effect on PQ-treated A549 cell lines as was demonstrated using the Calcein-AM fluorescence accumulation assay. In summary, MP induces the transmembrane ATP-dependent transporter P-gp expression, which greatly improves PQ-treated A549 cell viability, reduces accumulation of intracellular PQ and prevents PQ induced cytotoxicity but it should be further evaluated in in vivo studies.

Surfactant volume is an essential element in human toxicity in acute glyphosate herbicide intoxication

Background: Glyphosate, one of the most commonly used herbicides worldwide, has been considered as minimally toxic to humans. However, clinical toxicologists occasionally encounter cases of severe systemic toxicity. The purpose of this study was to determine the effect of glyphosate-surfactants (“glyphosate-surfactant toxicity”) in patients with acute glyphosate intoxication. Methods: In all, 107 patients (69 men and 38 women, aged 52.3 ± 15.5 years) with acute glyphosate intoxication were enrolled in this study. From their medical records, we identified the formulation of ingested glyphosate products and derived clinical parameters, which focused on clinical outcome, admission days, duration in the intensive care unit, development of respiratory failure, cardiovascular deterioration, renal failure, altered mental status, and convulsions. The effect of surfactants on clinical complications was also assessed. Results: For surfactant ingestion volumes of 8 mL, the incidence of clinical complications was (in rank order) as follows: hypotension, 47.1%; mental deterioration, 38.6%; respiratory failure, 30.0%; acute kidney injury, 17.1%; and arrhythmia, 10.0%. These complications were influenced by the volume of surfactant and not the type of surfactant-ingredient in the herbicide product. Two patients died of refractory shock, metabolic acidosis, and respiratory failure. However, the final clinical outcomes of the surviving patients were benign, and cardiovascular, respiratory, kidney, and mental functions were fully restored to normal levels. Conclusions: Our results indicate that treatment of patients with acute glyphosate herbicide intoxication should take into account the volume and not the type of surfactants in herbicide formulations.

Mixtures of glyphosate and surfactant TN20 accelerate cell death via mitochondrial damage-induced apoptosis and necrosis.

Glyphosate, a common herbicide, is not toxic under normal exposure circumstances. However, this chemical, when combined with a surfactant, is cytotoxic. In this study, the mechanism of the additive effect of glyphosate and TN-20, a common surfactant in glyphosate herbicides, was investigated. After exposure of rat H9c2 cells to glyphosate and TN-20 mixtures, following assays were performed: flow cytometry to determine the proportion of cells that underwent apoptosis and necrosis; western blotting to determine expression of mitochondrial proteins (Bcl-2 and Bax); immunological methods to evaluate translocation of cytochrome C; luminometric measurements to determine activity of caspases 3/7 and 9; and tetramethyl rhodamine methyl ester assay to measure mitochondrial membrane potentials. Bcl-1 intensity decreased while Bax intensity increased with exposure to increasing TN-20 and/or glyphosate concentrations. Caspase activity increased and mitochondrial membrane potential decreased only when the cells were exposed to a mixture of both TN-20 and glyphosate, but not after exposure to either one of these compounds. The results support the possibility that mixtures of glyphosate and TN-20 aggravate mitochondrial damage and induce apoptosis and necrosis. Throughout this process, TN-20 seems to disrupt the integrity of the cellular barrier to glyphosate uptake, promoting glyphosate-mediated toxicity.

Antioxidant effect of silymarin on paraquat-induced human lung adenocarcinoma A549 cell line

Paraquat (PQ) is not only widely used as a potent herbicide but also causes severe fatality to humans around the world due to accidental or intentional ingestion. Silymarin is a well-known phytochemical whose multi-functional effects in humans include anti-oxidant, anti-inflammatory and anti-cancer activities. The efficacy of silymarin in protecting against PQ-induced cytotoxicity is unknown. This study investigated the potential role of silymarin against PQ-induced oxidative stress on human A549 adenocarcinoma cell line. Colorimetric-based viability assay, determination of reactive oxygen species, cell damage assay based on lactate dehydrogense retention, anti-oxidant enzyme assay, Western blot and quantitative reverse transcription-polymerase chain reaction analyses were done. Our data revealed that silymarin could dramatically prevent cell toxicity, and reduce the LDH retention induced by PQ on A549 cell line. Silymarin acted as a potent cytoprotective effector through the effective induction of anti-oxidant related genes, including Nrf2, NQO1 and HO-1, in the presence of PQ. The induction of the Nrf2, HO-1 and NQO1 genes was first evident after 3h. The data indicate the potential of silymarin in alleviating PQ intoxication.

Suppression of the TRIF-dependent signaling pathway of toll-like receptors by isoliquiritigenin in RAW264.7 macrophages

Toll-like receptors (TLRs) play an important role in host defense by sensing invading microbial pathogens and initiating innate immune responses. The stimulation of TLRs by microbial components triggers the activation of myeloid differential factor 88 (MyD88)- and toll-interleukin-1 receptor domain-containing adapter inducing interferon-β (TRIF)-dependent downstream signaling pathways. Isoliquiritigen in (ILG), an active ingredient of Licorice, has been used for centuries to treat many chronic diseases. ILG inhibits the MyD88-dependent pathway by inhibiting the activity of inhibitor-κB kinase. However, it is not known whether ILG inhibits the TRIF-dependent pathway. To evaluate the therapeutic potential of ILG, we examined its effect on signal transduction via the TRIF-dependent pathway of TLRs induced by several agonists. ILG inhibited nuclear factor-κB and interferon regulatory factor 3 activation induced by lipopolysaccharide or polyinosinic-polycytidylic acid. ILG inhibited the lipopolysaccharide-induced phosphorylation of interferon regulatory factor 3 as well as interferon-inducible genes such as interferon inducible protein-10, and regulated activation of normal T-cell expressed and secreted (RANTES). These results suggest that ILG can modulate TRIF-dependent signaling pathways of TLRs, leading to decreased inflammatory gene expression.

Indoxyl sulfate promotes apoptosis in cultured osteoblast cells

BackgroundIndoxyl sulfate (IS), an organic anion uremic toxin, promotes the progression of renal dysfunction. Some studies have suggested that IS inhibits osteoclast differentiation and suppresses parathyroid hormone (PTH)-stimulated intracellular cAMP production, decreases PTH receptor expression, and induces oxidative stress in primary mouse calvaria osteoblast cell culture. However, the direct effects of IS on osteoblast apoptosis have not been fully evaluated. Hence, we investigated whether IS acts as a bone toxin by studying whether IS induces apoptosis and inhibits differentiation in the cultured osteoblast cell line MC3T3-E1.MethodsWe assessed the direct effect of IS on osteoblast differentiation and apoptosis in the MC3T3-E1 cell line. We examined caspase-3/7 activity, apoptosis-related proteins, free radical production, alkaline phosphatase activity, and mRNA expression of type 1 collagen and osteonectin. Furthermore, we investigated the uptake of IS via organic anion transport (OAT).ResultsWe found that IS increased caspase activity and induced apoptosis. Production of free radicals increased depending on the concentration of IS. Furthermore, IS inhibited the expression of mRNA type 1 collagen and osteonectin and alkaline phosphatase activity. The expression of OAT, which is known to mediate the cellular uptake of IS, was detected in in the MC3T3-E1 cell line. The inhibition of OAT improved cell viability and suppressed the production of reactive oxygen species. These results suggest that IS is transported in MC3T3-E1 cells via OAT, which causes oxidative stress to inhibit osteoblast differentiation.ConclusionsIS acts as a bone toxin by inhibiting osteoblast differentiation and inducing apoptosis.

Quercetin reduces oxidative damage induced by paraquat via modulating expression of antioxidant genes in A549 cells

Oxidative injury can occur in the lung through the generation of reactive oxygen species (ROS) via redox cycling owing to intentional or accidental ingestion of paraquat (PQ), a common herbicide. A wide array of phytochemicals has been shown to reduce cellular oxidative damage by modulating cytoprotective genes. Quercetin, a well‐known flavonoid, has been reported to display cytoprotective effects by up‐regulating certain cytoprotective genes. In this context, we investigated the effect of quercetin on PQ‐induced cytotoxicity in alveolar A549 cells, modulation of antioxidant genes, activation of transcription factor‐Nrf2 and its target HO‐1 expression. Quercetin reduced PQ‐induced cytotoxicity in A549 cells that was evaluated by both 3‐(4,5‐dimethylthiazol‐2‐yl)‐2, 5‐diphenyl‐tetrazolium bromide (MTT) and lactate dehydrogenase (LDH) assays. Modulation of antioxidant genes was compared when cells were treated with PQ, quercetin and both using qRT‐PCR. Activation of transcription factor‐Nrf2 and induction of its target gene, HO‐1 was demonstrated by western blot analysis. A remarkable reduction in the ROS level as well as an increase in the total cellular glutathione (GSH) level occurred when PQ‐exposed cells were treated with quercetin. Our findings suggest that quercetin may be used to mitigate or minimize oxidative stress via reducing the generation of ROS. Copyright

The dose of cyclophosphamide for treating paraquat-induced rat lung injury

Background/Aims Cyclophosphamide (CP) is a promising treatment for severe cases of paraquat (PQ) poisoning. We investigated the effective dose of CP for mitigating PQ-induced lung injury. Methods Adult male Sprague-Dawley rats were allocated into five groups: control, PQ (35 mg/kg, intraperitoneal injection), and PQ + CP (1.5, 15, or 30 mg/kg). The dimensions of lung lesions were determined using X-ray microtomography (micro-CT), and histological changes and cytokine levels were recorded. Results The micro-CT results showed that 15 mg/kg CP was more effective than 1.5 mg/kg CP for treating PQ-induced lung injury. At a dose of 1.5 mg/kg, CP alleviated the histological evidence of inflammation and altered superoxide dismutase activity. Using 15 mg/kg CP reduced the elevated catalase activity and serum transforming growth factor (TGF)-β1 level. Conclusions A CP dose of > 15 mg/kg is effective for reducing the severity of PQ-induced lung injury as determined by histological and micro-CT tissue examination, possibly by modulating antioxidant enzyme and TGF-β1 levels.