Younghee Kim

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).

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.

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.

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.

The Time between Paraquat Ingestion and a Negative Dithionite Urine Test in an Independent Risk Factor for Death and Organ Failure in Acute Paraquat Intoxication

To identify a prognostic marker that is less sensitive to variations in the elapsed time since paraquat ingestion, we assessed the time between paraquat ingestion and a negative dithionite urine test as a prognostic parameter in patients with acute paraquat intoxication. Forty-one patients with acute paraquat intoxication were enrolled in this study and analyzed to verify significant determinants of mortality and organ dysfunction. The amount of paraquat ingested, paraquat plasma levels, and the time to a negative urine dithionite test were significant independent risk factors predicting mortality. The amount of paraquat ingestion, and the time to a negative urine dithionite test were independent risk factors predicting organ dysfunction. With a cut-off value of 34.5 hr for the time to negative conversion of the urine dithionite test, the sensitivity and specificity for mortality were 71.4% and 75.0%, respectively. The incidence of acute kidney injury and respiratory failure above 34.5 hr were 100% and 85.0%, respectively. In conclusion, the time to a negative urine dithionite test is the reliable marker for predicting mortality and/or essential organ failure in patients with acute paraquat intoxication, who survive 72 hr.

Effects of Macrophage on Biodegradation of β-tricalcium Phosphate Bone Graft Substitute

Various calcium phosphate bioceramics are distinguished by their excellent biocompatibility and osteoconductivity. Especially, the exceptional biodegradability of β-TCP makes it a bone graft substitute of choice in many clinical applications. The activation of osteoclasts, differentiated from macrophage precursor cells, trigger a cell-mediated resorption mechanism that renders β-TCP biodegradable. Based on this evidence, we studied the biodegradation process of granular-type β-TCP bone graft substitute through in vitro and in vivo studies. Raw 264.7 cells treated with RANKL and M-CSF differentiated into osteoclasts with macrophage-like properties, as observed with TRAP stain. These osteoclasts were cultured with β-TCP nano powders synthesized by microwaveassisted process. We confirmed the phagocytosis of osteoclasts by observing β-TCP particles in their phagosomes via electron microscopy. No damage to the osteoclasts during phagocytosis was observed, nor did the β-TCP powders show any sign of cytotoxicity. We also observed the histological changes in subcutaneous tissues of rats implanted with granule-type β-TCP synthesized by fibrous monolithic process. The β-TCP bone graft substitute was well surrounded with fibrous tissue, and 4 months after implantation, 60% of its mass had been biodegraded. Also, histological findings via H&E stain showed a higher level of infiltration of lymphocytes as well as macrophages around the granule-type β-TCP. From the results, we have concluded that macrophages play an important role in the biodegradation process of β-TCP bone graft substitutes.

In vitro and in vivo evaluations of 3D porous TCP-coated and non-coated alumina scaffolds.

Both tricalcium phosphate (TCP) and alumina have been extensively studied and shown to have high biocompatibility. Tricalcium phosphate has improved biodegradability and a higher solubility than hydroxyapatite. In contrast, alumina (Al2O3) is almost completely inert at physiological conditions and has been used as a biomaterial due to its wear resistance, high surface finish, and excellent hardness. Thus, the combination of these two implants would result in greater biocompatibility and phenotype maintenance. A polyurethane (PU) foam replica method was employed in this study to coat TCP on an alumina scaffold. The TCP-coated alumina scaffold was then sintered to generate a porous surface morphology. The pore sizes obtained using this approach ranged between 100—600 µm, which is ideal for cellular proliferation. The cytotoxicity, cellular proliferation, differentiation, and ECM deposition on the coated scaffold resulted in longer-term viability of osteogenic markers compared to the non-coated scaffold. Moreover, the osteogenic properties of porous TCP-coated Al2O3 scaffolds were reported in this study using rabbit models. The TCP/Al2O 3 scaffold and control Al2O3 scaffolds were implanted in the rabbit femur. The bone tissue response was analyzed with micro-computed tomography (micro CT) at 12 and 24 weeks after implantation. The porous scaffolds exhibited favorable hard and soft tissue responses at both time points. At 24 weeks, a three-fold increase in bone tissue ingrowth was observed in defects containing TCP-coated Al2O3 scaffolds compared to control Al2O3 scaffolds.

In vitro and in vivo evaluation of a macro porous β-TCP granule-shaped bone substitute fabricated by the fibrous monolithic process

In this study, a new porous beta-tricalcium phosphate (β-TCP) granule was fabricated using the fibrous monolithic (FM) process and its in vitro biocompatibility and in vivo bone formation were evaluated. SEM micrograph images showed that MG-63 cells attached to the surfaces of the implant and were well proliferated. Cellular viability was as high as 75% in a50% extract dilution solution. cDNA micro array analysis was also carried out. In this analysis, we found a total of 12 up-regulated and 25 down-regulated genes. Four rabbits were used in the in vivo experiments. 3D micro-CT images showed that the formation of new bone was almost three times greater than that of normal trabecular bone (BV/TV). The histomorphometric results correlated with the micro-CT findings; a greater amount of new bone formation and osteoblast lineage along with osteocytes were observed in the implanted animals. Also x-ray radiographic and 2D micro-CT images were taken to demonstrate the superior biodegradability of the porous granule. As biodegradation occurred along with bone formation, 6 months after implantation, the porous granule structure was not distinguishable separately from that of the trabecular bone.

Ratio of angiopoietin-2 to angiopoietin-1 predicts mortality in acute lung injury induced by paraquat.

Background To determine whether initial reactive oxygen species (ROS)-induced endothelial cell injury is involved in early death after paraquat intoxication and concentrations of angiopoietin-1 (Ang-1), angiopoietin-2 (Ang-2), and von Willebrand factor (VWF) reflecting endothelial cell injury, we investigated the initial endothelial cell injury marker involved in the pathogenesis of death within 5 days after paraquat ingestion. Material/Methods Sixty patients with paraquat poisoning were prospectively enrolled. Plasma samples were collected at admission. Plasma concentrations of Ang-1, Ang-2, and VWF were measured by enzyme-linked immunosorbent assay. The patients were classified into 3 categories: survivors, early death (died within 5 days after ingestion), and late death (died more than 5 days after ingestion). Results The baseline concentration of Ang-2 and the Ang-2: Ang-1 ratio were significantly higher in patients who died (Ang-2 [pg/mL], 1012.75±468.02 vs. 1986.07±1675.37 [p=0.002]; Ang-2: Ang-1, 0.90±0.49 vs. 2.16±2.28 [p=0.002]). The Ang-2: Ang-1 ratio was significantly higher in the early death group (2.41±2.54) than in the survivors (0.90±0.49) and the late death group (1.33±0.64). The Ang-2: Ang-1 ratio was significantly associated with early death (OR, 2.602; 95% CI, 1.106–6.117; p=0.028) after adjusting for plasma levels of paraquat, age, PCO2, and creatinine. VWF did not predict mortality. Conclusions Endothelial cell damage could be involved in the pathogenesis of early death following paraquat ingestion.

Antimycobacterial activity of methanolic plant extract of Artemisia capillaris containing ursolic acid and hydroquinone against Mycobacterium tuberculosis

OBJECTIVEnIn order to protect against Mycobacterium tuberculosis (MTB) infection, novel drugs and new targets should be screened from the vast source of plants. We investigated the potentiality of the herbal plant of Artemisia capillaris extract (AC) against Mycobacterium tuberculosis.nnnDESIGNnIn this study, we isolated ursolic acid and hydroquinone by bio-activity guided fractionation from the methanol extracts of AC, and tested the inhibitory effects against several strains of MTB. Anti-mycobacterial evaluation of these compounds was carried out using the MGIT™ 960 and resazurin assay. Mycobacterial morphological changes due to the treatment of these compounds were further evaluated by Transmission electron microscopy (TEM).nnnRESULTSnUrsolic acid (UA) and hydroquinone (HQ) inhibited the growth of both susceptible and resistant strains of M.xa0tuberculosis. The MIC (minimum inhibitory concentration) values of both UA and HQ were 12.5xa0μg/ml against the susceptible strains of M.xa0tuberculosis. Also both UA and HQ showed 12.5-25xa0μg/ml of MIC values against MDR/XDR MTB strains. However, against clinical strains of MTB, UA was found sensitive against those strains that are sensitive against both INH and RFP but resistant against those strains that are resistant to INH. On the other hand HQ was sensitive against all clinical strains. TEM image-analysis of the strain H37Ra after treatment with UA revealed cell wall lysis, whereas HQ-treated cells showed deformed cytoplasmic morphology.nnnCONCLUSIONnAll these results indicate that AC extracts containing UA and HQ possess promising chemotherapeutic potency against MTB for future use.