• Nuclear Engineering and Technology
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• v.28 no.2
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• pp.103-117
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• 1996

A mathematical model of vapor explosion propagation is presented. The model predict two-dimensional, transient flow fields and energies of the four fluid phases of melt drop, fragmented debris, liquid coolant and vapor coolant by solving a set of governing equations with the relevant constitutive relations. These relations include melt fragmentation, coolant-phase-change, and heat and momentum exchange models. To allow thermodynamic non-equilibrium between the coolant liquid and vapor, an equation of state for oater is uniquely formulated. A multiphase code, TRACER, has been developed based on this mathematical formulation. A set of base calculations for tin/water explosions show that the model predicts the explosion propagation speed and peak pressure in a reasonable degree although the quantitative agreement relies strongly on the parameters in the constitutive relations. A set of calculations for sensitivity studies on these parameters have identified the important initial conditions and relations. These are melt fragmentation rate, momentum exchange function, heat transfer function and coolant phase change model as well as local vapor fractions and fuel fractions.

• Asian Pacific Journal of Cancer Prevention
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• v.17 no.4
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• pp.2151-2157
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• 2016

Scabraside D, a sulfated triterpene glycoside, was extracted from the sea cucumber Holothuria scabra. It shows anti-proliferation in many of cancer cell lines, but the function and mechanisms of action of scabraside D in human cholangiocarcinoma (HuCCA) have not previously determined. In this study, we investigated the activity of scabraside D on HuCCA cell apoptosis, lymphangiogenesis and metastasis in a nude mouse model. Scabraside D induced signs of apoptosis, such as cell shrinkage, nuclear condensation, nuclear fragmentation and DNA fragmentation on TUNEL assays, while effectively decreasing expression of BCl-2 but increasing caspase-3 gene level expression. Immunohistochemistry revealed that scabraside D significantly reduced lymphatic vessel density (LVD). Moreover, scabraside D treatment significantly decreased VEGF-C, MMP-9 and uPA gene expression, which play important roles in the lymphangiogenesis and invasion of cancer cells in metastasis processes. Quantitative real-time PCR showed that scabraside D significantly decreased iNOS and STAT-3 gene expression. This study demonstrated that scabraside D plays a role in activation of HuCCA tumor apoptosis and inhibition of lymphangiogenesis, invasion and metastasis through decreasing BCl-2, MMP-9, uPA and VEGF-C and increasing caspase-3 expression by suppression of iNOS and STAT-3 expression. Therefore, scabraside D could be a promising candidate for cholangiocarcinoma treatment.

• International Journal of Oral Biology
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• v.45 no.1
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• pp.8-14
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• 2020

Bilobalide isolated from the leaves of Ginkgo biloba has several pharmacological activities such as neuroprotective, anti-inflammatory, and anticonvulsant. However, the effect of bilobalide on cancer has not been clearly established. The main purpose of this study was to investigate the effect of bilobalide on cell growth and apoptosis induction in FaDu human pharyngeal squamous cell carcinoma. This was examined by 3-[4,5-dimethylthiazol-2-yl]-2,5-diphenyltetrazolium bromide assay, nuclear 4′,6-diamidino-2-phenylindole dihydrochloride staining, DNA fragmentation analysis, and immunoblotting. Bilobalide inhibited the growth of FaDu cells in dose- and time-dependent manners. Treatment with bilobalide resulted in nuclear condensation and DNA fragmentation in FaDu cells. Furthermore, it promoted the proteolytic cleavage of procaspase-3/-7/-8/-9 with increase in the amount of cleaved caspase-3/-7/-8/-9. Bilobalide-induced apoptosis in FaDu cells was mediated by the expression of Fas and the activation of caspase-8, caspase-3, and poly (ADP-ribose) polymerase. Immunoblotting revealed that the antiapoptotic mitochondrial protein Bcl-2 was downregulated, but the proapoptotic protein Bax was upregulated by bilobalide in FaDu cells. Bilobalide significantly increased Bax/Bcl-2 ratio. These results suggest that bilobalide inhibits cell proliferation and induces apoptosis in FaDu human pharyngeal squamous cell carcinoma via both the death receptor-mediated extrinsic apoptotic pathway and the mitochondrial-mediated intrinsic apoptotic pathway.

• Nuclear Engineering and Technology
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• v.32 no.6
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• pp.549-558
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• 2000

A transient model for hydrogen generation in molten metal-water interactions was developed with separate models for two stages of coarse mixing and stratification. The model selves the mechanistic equations (heat and mass transfer correlation, heat conduction equation and the concentration diffusion equation) of each stage with non-zero boundary conditions. Using this model, numerical simulations were performed for single droplet experiments in the Argonne National Laboratory tests and for FITS tests that simulated dynamic fragmentation and stratification. The calculation results of hydrogen generation showed better agreement to the experiment data than those of previous works. It was found from the analyses that the steam concentration to be reached at the reaction front might be the main constraint to the extent of the metal droplet oxidized. Also, the hydrogen generation rate in the coarse mixing stage was the higher than that in the stratification stage. The particle size was the most important factor in the coarse mixing stage to predict the amount of hydrogen generation.

• Journal of Life Science
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• v.12 no.2
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• pp.182-187
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• 2002

In this study we have investigated the effect of Caesalpina sappann L. extracts on the apoptosis in NIH3T3 cells exposed to methylmethan sulfonate (MMS), an alkylating agent. MTT assay study showed that Caesalpina sappan L. extracts potentiate the MMS-induced viability. Cell morphology studies, acridine orange (AO) staining, and DNA fragmentation analysis indicated that the postincubation of Caesalpina sappan L. extracts increase the nuclear condensation of MMS-induced apoptotosis. These results suggest that Caesalpina sampan L. extracts contain components potentiating MMS-induced apoptosis of NIH3T3 cells.

• Journal of Korean Neurosurgical Society
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• v.30 no.sup1
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• pp.5-12
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• 2001

This study was designed to investigate the mechanism of cell death after cisplatin treatment in human glioblastoma A172 cells. Cis-diamminedichloroplatinum(Cisplatin) demonstrated cytostatic or cytotoxic effects on A172 cells in a dosedependent manner. Cisplatin-mediated cytotoxity in A172 cells was revealed as an apoptosis characterized by high molecular weight DNA fragmentation by agarose electrophoresis as well as nuclear fragmentation by Hoechst staining. Cisplatin also resulted in the activation of caspase 3-like protease as well as poly(ADP-ribose) polymerase(PARP) cleavage. Interestingly, the anti-apoptotic Bcl2 protein was degraded and furthermore, expression of p53 protein was increased by cisplatin in a time-dependent manner. Taken together, these results suggest that anticancer drug, cisplatin induces the apoptotic death of human glioblastoma A172 cells via the activations of caspase 3-like protease, degradation of anti-apoptotic Bcl2 protein and increase in the expression of p53.

• The Journal of Korean Medicine
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• v.23 no.1
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• pp.50-60
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• 2002

Objectives: Sunghyangjunggisan (SHJS) is a commonly prescribed drug with a wide neuropharmacological spectrum. The water extracts of SHJS were found to be protective against neurotoxicity elicited by deprivation of serum and glucose. Methods: The morphological examination and Hoechst staining of nucleus also clearly showed that the extracts attenuated the cell shrinkage, membrane blebbing, representing typical neuronal apoptotic phenomena and nucleosome-sized fragmentation under the microscope in PC 12 rat pheochromocytoma cells. Results: Activation of protein kinase A (PKA) with dibutyl-cAMP and forskolin also protected during glucose deprivation, although it was not additive with the effect provided by phorbol ester. Interestingly, treatment with the protein kinase A inhibitor, KT5720, was not neuroprotective in the presence of SHJS. Electrophoretic mobility shift assays were used to characterize the neuroprotective binding of nuclear proteins to consensus sequences for AP-l, nuclear factor kappa B ($NF-{\kappa}B$) after glucose deprivation. When PC 12 cells are induced to undergo apoptosis by serum deprivation, AP-l and $NF-{\kappa}B$ DNA binding activity transiently increases to a slight degree. This stimulation is blocked by the water extracts of SHJS. The site of action of the drugs appeared to involve specific inhibition of AP-1 and nuclear factor kB binding activity. Conclusions: Taken together, these results suggested the possibility that the extracts of SHJS might provide a neurotrophic-like activity in PC 12 cells.

• Nuclear Engineering and Technology
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• v.53 no.1
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• pp.79-92
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• 2021

Venturi tube is based on turbulent flow, whereby the microbubbles can be generated by the turbulent fragmentation. This phenomenon is common in several venturi bubblers used by the nuclear, aerospace and chemical industries. The first objective of this paper is to study the liquid-phase velocity field experimentally and develop correlations for the turbulent quantities. The second objective is to research velocity field characteristics theoretically. Stereoscopic PIV measurements for the velocity field have been analyzed and utilized to develop the turbulent kinetic energy in the venturi tube. The tracking properties of the tracer particles have been verified enough for us to analyze the turbulence field. The turbulence kinetic energy has a bimodal distribution trend. Also, the results of turbulence intensity along the horizontal direction is gradually uniform along the downstream. Both the mean velocity and the fluctuation velocity are proportional to the Reynolds number. Besides, the distribution trend of the mean velocity and the velocity fluctuation can be determined by the geometric parameters of the venturi tube. An analytical function model for the flow field has been developed to obtain the approximate analytical solutions. Good agreement is observed between the model predictions and experimental data.

• Journal of the Korean Society of Food Science and Nutrition
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• v.31 no.4
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• pp.672-678
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• 2002

Oxidative stress contributes to cellular injury following clinical and experimental ischemia/reperfusion scenarios. Oxidative injury can induce cellular and nuclear damages that result in apoptotic cell death. We tested the hypothesis that the catechin flavonoid of (-)epigallocatechin gallate, a green tea polyphenol, inhibits hydrogen peroxide ($H_2O$$_2$)-induced apoptosis in human umbilical vein endothelial cells. The effect of apigenin, a flavone found in citrus fruits, on apoptosis parameters was also examined. A 30 min pulse treatment with 0.25 mM $H_2O$$_2$ decreased endothelial cell viability within 24 hrs by > 30% ; this was associated with nuclear condensation and biochemical DNA damage consistent with programmed cell death. In the 0.25 mM $H_2O$$_2$apoptosis model, 50${\mu}{\textrm}{m}$ (-)epigallocatechin gallate markedly increased cell viability with a reduction in the nuclear condensation and DNA fragmentation. In contrast, equimicromolar apigenin increased cell loss with intense DNA laddering, positive nick-end labeling and Hoechst 33258 staining. Thus, polyphenolic (-)epigallocatechin gallate, but not apigenin flavone, qualify as an antioxidant in apoptosis models caused by oxidative stress. Further work is necessary for elucidating the anti-apoptotic mechanisms of polyphenolic catechins.

• Journal of Life Science
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• v.17 no.1 s.81
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• pp.64-69
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• 2007

In the present study, we have investigated the effect of fisetin on the apoptosis and DNA single strand breaks in ultraviolet light B (UVB)-exposed NIH3T3 cells. Exposure of cells to UVB light $(200J/m^2)$ and post-incubation in growth medium for 48 hr resulted in about 50% of cells with apoptotic nuclear fragmentation. Addition of various concentrations of fisetin in the postincubation medium, however, significantly reduced the apoptotic nuclear fragmentation as compared with the values expected when the effects are additive and independent. DNA single strand breaks induced by UVB exposure were also significantly decreased by postincubation with fisetin. By Western blot analysis, fisetin post-incubation was shown to attenuate the p53 upregulation upon UVB exposure. Furthermore, the decrease of proliferating cell nuclear antigen (PCNA) level upon UVB exposure was alleviated by fisetin postincubation. These results suggest that fisetin decrease the apoptosis and increae DNA repair in a possible association with alteration of p53 and PCNA levels in UVB-exposed cells.