• The Korean Journal of Physiology and Pharmacology
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• v.21 no.2
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• pp.215-223
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• 2017

The effects of acidic pH on several voltage-dependent ion channels, such as voltage-dependent $K^+$ and $Ca^{2+}$ channels, and hyperpolarization-gated and cyclic nucleotide-activated cation (HCN) channels, were examined using a whole-cell patch clamp technique on mechanically isolated rat mesencephalic trigeminal nucleus neurons. The application of a pH 6.5 solution had no effect on the peak amplitude of voltage-dependent $K^+$currents. A pH 6.0 solution slightly, but significantly inhibited the peak amplitude of voltage-dependent $K^+$ currents. The pH 6.0 also shifted both the current-voltage and conductance-voltage relationships to the depolarization range. The application of a pH 6.5 solution scarcely affected the peak amplitude of membrane currents mediated by HCN channels, which were profoundly inhibited by the general HCN channel blocker $Cs^+$ (1 mM). However, the pH 6.0 solution slightly, but significantly inhibited the peak amplitude of HCN-mediated currents. Although the pH 6.0 solution showed complex modulation of the current-voltage and conductance-voltage relationships, the midpoint voltages for the activation of HCN channels were not changed by acidic pH. On the other hand, voltage-dependent $Ca^{2+}$ channels were significantly inhibited by an acidic pH. The application of an acidic pH solution significantly shifted the current-voltage and conductance-voltage relationships to the depolarization range. The modulation of several voltage-dependent ion channels by an acidic pH might affect the excitability of mesencephalic trigeminal nucleus neurons, and thus physiological functions mediated by the mesencephalic trigeminal nucleus could be affected in acidic pH conditions.

• Polymer(Korea)
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• v.35 no.6
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• pp.520-525
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• 2011

Superporous hydrogels (SPHs) with fast swelling and superabsorbent properties are useful materials in various biomedical fields, by improving the swelling properties of conventional hydrogels based on their unique porous structure. In this study, Eudragit polymers were used as coating materials to control the swelling properties of poly(acrylic acid-co-acrylamide) based SPHs by environmental pH. The SPHs were coated with Eudragit L100 and S100 that have different pH characteristics as enteric coating materials by a dip coating method, and their pH dependent swelling behaviors were observed in various pH environments. The swelling of SPHs was inhibited at a low pH range, but significantly enhanced above a characteristic pH of Eudragit polymers. This pH dependent swelling behavior of hydrogels could be modulated by the characteristics of the enteric coating polymers.

• Clinical Nutrition Research
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• v.5 no.3
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• pp.172-179
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• 2016

Acid food indicators can be used as pH indicators for evaluating the quality and freshness of fermented products during the full course of distribution. Iron oxide particles are hardly suspended in water, but partially or completely agglomerated. The agglomeration degree of the iron oxide particles depends on the pH. The pH-dependent particle agglomeration or dispersion can be useful for monitoring the acidity of food. The zeta potential of iron oxide showed a decreasing trend as the pH increased from 2 to 8, while the point of zero charge (PZC) was observed around at pH 6.0-7.0. These results suggested that the size of the iron oxide particles was affected by the change in pH levels. As a result, the particle sizes of iron oxide were smaller at lower pH than at neutral pH. In addition, agglomeration of the iron oxide particles increased as the pH increased from 2 to 7. In the time-dependent aggregation test, the average particle size was 730.4 nm and 1,340.3 nm at pH 2 and 7, respectively. These properties of iron oxide particles can be used to develop an ideal acid indicator for food pH and to monitor food quality, besides a colorant or nutrient for nutrition enhancement and sensory promotion in food industry.

• Journal of Pharmaceutical Investigation
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• v.19 no.4
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• pp.179-183
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• 1989

Drug release experiments were performed based on pH-sensitive swelling behaviors of polymethacrylic acid. 5-Fluorouracil as a nonionic model drug revealed release patterns depending solely on pH-dependent swelling kinetics of polymethacrylic acid. In contrast, release of propranolol hydrochloride as a cationic model drug was significantly affected by ionic drug-polymer interaction as well as the swelling kinetics. Accordingly, a zero-order release pattern was obtained at pH 7, which was distinguished from the general matrix type drug release pattern.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 1993.11a
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• pp.124-127
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• 1993

In this paper, the magnetic properties of Ni-Zn ferrite powders dependent on pH have been studied. Ni-Zn ferrite powders were synthesized by coprecipitation method(pH were 7. 9. 11 and 13. respetively) using FeCl$_3$$.$ 6H$_2$O, NiCl$_2$$.$6H$_2$O and ZnCl$_2$as starting materials and its powders were calcined at 1,000($^{\circ}C$). The saturated magnetizations of the Ni-Zn ferrite powders dependent on various pH. such as 7, 9, 11 and 13 were 11.44, 29.77, 69.62 and 66.75(emu/g), respetively.

• Biomedical Science Letters
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• v.22 no.4
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• pp.184-188
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• 2016

The objective of this study was to develop a pH dependent oral matrix tablet containing probiotics. In this study, hydroxyl-propyl-methyl-cellulose (HPMC) and polyvinyl pyrrolidone K30 (PVP K-30) was utilized as a binder, sodium starch glycolate (SSG) was used as a disintegrant material for the tablet formulation. The disintegration test, hardness test, angle of response were performed to examine the characteristics of prepared tablet. Lactobacillus vitality test was applied to analyze the total Lactobacillus viable count. The results demonstrated that the pH dependent matrix tablet was prepared successfully and can thus be industrialized instead of the current methodologies used for preparation of conventional probiotics.

• Journal of Applied Biological Chemistry
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• v.42 no.3
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• pp.151-153
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• 1999

Gromwell (Lithospermum erythrorhizon) pigment solution and Jindo Hongju prepared in the laboratory showed characteristic pH-dependent color changes and a shift in absorption maxima. This phenomenon was not observed in the solution of the artificial food colorant Red No. 2 which was suspected to be used in the manufacture of fake Jindo Hongju. A few fake products could be detected by using the pH-dependent shift in absorption maxima among the Jindo Hongju on market.

• Proceedings of the Korean Geotechical Society Conference
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• 2005.03a
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• pp.1047-1054
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• 2005

The purpose of this study is the understanding to changes in the characteristic of soil structure and classification, atterberg limits, undrained shear strength and consolidation of clayey soil dependent on pH of soil pore water. A series of tests including consistency tests, uniaxial compressive tests, vane tests and oedometer tests are performed on. The test results indicated that pH changes in the soil pH resulted in changes in the soil structure and classification, stress-strain behavior. Specially, when pH is conditioned to 7, liquid limit, undrained shear strength and preconsolidation pressure are the largest.

• BMB Reports
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• v.47 no.10
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• pp.575-580
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• 2014

In this study, we investigate whether arsenite-induced DNA damage leads to p53-dependent premature senescence using human glioblastoma cells with p53-wild type (U87MG-neo) and p53 deficient (U87MG-E6). A dose dependent relationship between arsenite and reduced cell growth is demonstrated, as well as induced ${\gamma}H2AX$ foci formation in both U87MG-neo and U87MG-E6 cells at low concentrations of arsenite. Senescence was induced by arsenite with senescence-associated ${\beta}$-galactosidase staining. Dimethyl- and trimethyl-lysine 9 of histone H3 (H3DMK9 and H3TMK9) foci formation was accompanied by p21 accumulation only in U87MG-neo but not in U87MG-E6 cells. This suggests that arsenite induces premature senescence as a result of DNA damage with heterochromatin forming through a p53/p21 dependent pathway. p21 and p53 siRNA consistently decreased H3TMK9 foci formation in U87M G-neo but not in U87MG-E6 cells after arsenite treatment. Taken together, arsenite reduces cell growth independently of p53 and induces premature senescence via p53/p21-dependent pathway following DNA damage.

• Journal of Microbiology
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• v.40 no.2
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• pp.125-128
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• 2002

The aerobic respiratory chain of Vibrio alginolyticus possesses two different kinds of NADH oxidase systems, i.e., an $Na^{+}$-dependent NADH oxidase system and an $Na^{+}$-independent NADH oxidase system. When deamino-NADH, which is the only substrate for the $Na^{+}$-dependent NADH oxidase system, was used as a substrate, the maximum activities of $N^{+}$-dependent NADH: quinone oxidoreductase and $Na^{+}$-dependent NADH oxidase were obtained at about 0.06 M and 0.2 M NaCl, respectively. When NADH, which is a substrate for both $Na^{+}$-dependent and $Na^{+}$-independent NADH oxidase systems was used as a substrate, the NADH oxidase activity had a pH optimum at about 8.0. In cGntrastl when deamino-NADH was used as a substrate, the NADH oxidase activity had a pH optimum at about 9.0. On the other handle inside-out membrane vesicles prepared from the wild-type bacterium generated only a very small $\Delta$pH by the NADH oxidase system, whereas inside-out membrane vesicles prepared from Napl, which is a mutant defective in the $Na^{+}$ pump, generated $\Delta$pH to a considerable extent by the NADH oxidase system. On the basis of the results\ulcorner it was concluded that the respiratory chain-linked components of V. atginotyticus affect each other.