Jung-Kue Shin

p38 Mitogen-activated protein kinase modulates expression of tumor necrosis factor-related apoptosis-inducing ligand induced by interferon-γ in fetal brain astrocytes

This study describes the involvement of the p38 mitogen‐activated protein kinase (MAPK) during interferon‐γ (IFN‐γ) signaling in fetal brain astrocytes. In some pathological conditions of brain, p38 MAPK transduces stress‐related signals, increases expression of proinflammatory cytokines, and induces cellular damage or apoptosis. In astrocytes, the tumor necrosis factor (TNF)‐related apoptosis‐inducing ligand (TRAIL) expression level was increased by IFN‐γ. AG490, a JAK inhibitor, blocked TRAIL expression induced by IFN‐γ. SB203580, a specific p38α and p38β2 MAPK inhibitor, decreased the TRAIL expression induced by IFN‐γ. The phosphorylation of the Ser727 site of STAT1, but not the Tyr701 site, was inhibited by SB203580. These results suggest that p38 MAPK modulates STAT1 phosphorylation in IFN‐γ signaling in fetal brain astrocytes.

Overexpression of LIM Kinase 1 Renders Resistance to Apoptosis in PC12 Cells by Inhibition of Caspase Activation

LIM kinases (LIMKs) regulate actin polymerization by phosphorylating cofilin and are predominantly expressed in neural tissue. In this study, the effect of LIMK1 overexpression in PC12 cell apoptosis was investigated. PC12 cells overexpressing the wild-type LIMK1 were more resistant to serum-withdrawal-induced cell death and the level of caspase 3 activation in these cells was lower than in the control PC12 cells or than in the PC12 cells expressing a mutant LIMK1 lacking the kinase domain. The inhibition of JNK activation was observed in the PC12 cells overexpressing the wild-type LIMK1 after serum withdrawal. These results suggest that the LIMK1 might allow resistance to apoptosis in PC12 cells by inhibiting JNK activation.

A Study of Sodium Reduction Effect in Foods Using Fermented Soy Sauce

Salt (NaCl) is one of the most important main source of sodium in our diet. However, health concerns related to salt overconsumption have led to an increased demand for salt-reduced food. The objective of this study was to investigate the possibility of the use of fermented soy sauce to reduce the level of salt in foods. The contents of sodium in bean sprout soup and chicken rice porridge prepared with salt were 1.59±0.05 and 1.89±0.03 g/L, respectively. Whereas, the sodium content range of the same samples prepared with soy sauce were 0.38±0.01-1.54±0.02 and 0.37±0.00-1.44±0.01 g/L, respectively. Paired difference test between control and various soy sauce samples was used to provide the amount of soy sauce needed to replace salt without changing the overall taste and intensity. The results showed that sodium reduction (22.0-69.3%) could be achieved in tested foods with the fermented soy sauce.

Salty Taste Enhancing Effect of Enzymatically Hydrolyzed Anchovy Protein in Cooking Application

The purpose of this study was to investigate the possibility of the use of enzymatically hydrolyzed anchovy protein (eHAP) to enhancing of salty taste in dried pollack soup and mungbean sprout when it was applied in cooking. The salty taste enhancing effect was evaluated by comparing the dried pollack soup samples with eHAP added and the control sample containing 0.6% NaCl, and the result showed that the salty taste enhancing effect was 15%, 25%, 42%, and 46% in the samples with 0.1%, 0.5%, 1.0%, and 1.5% eHAP added, respectively. The overall acceptability was decreased as the eHAP addition was increased. In case of a bean sprout containing 0.7% NaCl, the salty taste enhancing effect was 29%, 18%, 16%, and 31% in the 0.1%, 0.5%, 1.0%, and 1.5% eHAP added, respectively. The lightness and yellowness were decreased as the eHAP addition was increased in both the dried pollack soup and the bean sprout. The pH of the dried pollack soup was decreased but the pH of the bean sprout dish was increased as the addition of eHAP was increased. The application of eHAP to food showed a significant salty taste enhancing effect, but the effect was dependent on the type of foods.

Hydrolysis of Isolate Soybean Protein Using Subcritical Water

Hydrolysis of isolate soybean protein (ISP) using subcritical water (SCW) was conducted to study the feasibility for producing protein hydrolyzate. SCW hydrolysis of SPI suspension (5-15%) was conducted in an electrically heated batch reactor (2 L). The effects of temperature (230 to 270 o C) and holding time (10 to 50 min) on the degree of hydrolysis (DH) and the production of amino acids were studied by surface response method. The DH was determined by derivatizing the hydrolyzates with ortho-phthalaldehyde (OPA) solution. It was confirmed that reaction temperature and holding time affected the hydrothermolysis of soybean protein. However, the holding time was less effective on amino acid yield when the temperature was higher than 230 o C. In order to achieve optimal yields of amino acids exceeding 43%, the temperature should be within the range between 256 and 268 o C with holding time from 29 to 41 min, respectively. A maximum estimated amino acid yield of 43.5% was obtained at 268 o C for 35 min.