Choonshik Shin

Early immature neuronal death initiates cerebral ischemia-induced neurogenesis in the dentate gyrus

Throughout adulthood, neurons are continuously replaced by new cells in the dentate gyrus (DG) of the hippocampus, and this neurogenesis is increased by various neuronal injuries including ischemic stroke and seizure. While several mechanisms of this injury-induced neurogenesis have been elucidated, the initiation factor remains unclear. Here, we investigated which signal(s) trigger(s) ischemia-induced cell proliferation and neurogenesis in the hippocampal DG region. We found that early apoptotic cell death of the immature neurons occurred in the DG region following transient forebrain ischemia/reperfusion in mice. Moreover, early immature neuronal death in the DG initiated transient forebrain ischemia/reperfusion-induced neurogenesis through glycogen synthase kinase-3β/β-catenin signaling, which was mediated by microglia-derived insulin-like growth factor-1 (IGF-1). Additionally, we observed that the blockade of immature neuronal cell death, early microglial activation, or IGF-1 signaling attenuated ischemia-induced neurogenesis. These results suggest that early immature neuronal cell death initiates ischemia-induced neurogenesis through microglial IGF-1 in mice.

Novel anticancer agent, benzyldihydroxyoctenone, isolated from Streptomyces sp. causes G1 cell cycle arrest and induces apoptosis of HeLa cells

In the course of screening for anticancer agents, a novel active compound, F3‐2‐5, was isolated from culture broth of Streptomyces sp., KACC91015. Its structure was identified using nuclear magnetic resonance, mass spectrometry, and molecular modeling experiments, and confirmed by total synthesis. The growth of various human cancer cell lines was inhibited in a dose‐dependent manner by 0.06–0.48 mM F3‐2‐5 over 24 h. Its IC50 values were estimated at 37 µM on HeLa, 72 µM on A549, and 190 µM on HT‐29 cells. However, F3‐2‐5 had no antiproliferative effect on normal lymphocytes and normal fibroblasts used as controls. Moreover, it affected cell cycle regulation and caused apoptosis of the HeLa cells; chromatin condensation and DNA fragmentation were observed in cells exposed to 80 µM F3‐2‐5. Western blot analysis revealed that F3‐2‐5 inhibited phosphorylation of retinoblastoma protein (pRb) and reduced expression of cyclin‐dependent kinase‐4 and ‐6, and cyclin D1 and E, while levels of p53 and p21WAF1/CIP1 increased. Taken together, these findings show that F3‐2‐5 inhibits proliferation of HeLa cells by inducing G1 phase arrest as a consequence of inhibition of pRb phosphorylation following up‐regulation of p21WAF1/CIP1 and p53. Furthermore, apoptosis in HeLa cells treated with F3‐2‐5 was associated with an increase in Bax and p53, leading to release of cytochrome c, activation of caspase‐3, and ‐8, and cleavage of poly (ADP‐ribose) polymerase. (Cancer Sci 2007; 98: 795–802)

The potential role of melatonin on sleep deprivation-induced cognitive impairments: implication of FMRP on cognitive function.

While prolonged sleep deprivation (SD) could lead to profound negative health consequences, such as impairments in vital biological functions of immunity and cognition, melatonin possesses powerful ameliorating effects against those harmful insults. Melatonin has strong antioxidant and anti-inflammatory effects that help to restore bodys immune and cognitive functions. In this study, we investigated the possible role of melatonin in reversing cognitive dysfunction induced by SD in rats. Our experimental results revealed that sleep-deprived animals exhibited spatial memory impairment in the Morris water maze tasks compared with the control groups. Furthermore, there was an increased glial activation most prominent in the hippocampal region of the SD group compared to the normal control (NC) group. Additionally, markers of oxidative stress such as 4-hydroxynonenal (4-HNE) and 7,8-dihydro-8-oxo-deoxyguanine (8-oxo-dG) were significantly increased, while fragile X-mental retardation protein (FMRP) expression was decreased in the SD group. Interestingly, melatonin treatment normalized these events to control levels following SD. Our data demonstrate that SD induces oxidative stress through glial activation and decreases FMRP expression in the neurons. Furthermore, our results suggest the efficacy of melatonin for the treatment of sleep-related neuronal dysfunction, which occurs in neurological disorders such as Alzheimers disease and autism.

Analysis of Zearalenone Contamination in Cereal-Based Products Using High Performance Liquid Chromatography-Fluorescence Detector and Ultra Performance Liquid Chromatography-Tandem Mass Spectrometry

Department of Food Science and Technology, Pukyong National UniversityAbstract Zearalenone (ZEA) is an estrogenic mycotoxin mainly produced by Fusarium graminerum, a species whichcolonizes a wide variety of cereals, including wheat, barley and processed products. A survey of ZEA contamination wasconducted on 141 dried confectioneries, 59 breads and rice cakes, 135 noodles and 101 other products, for a total of 432commercial samples. Samples were analyzed by high performance liquid chromatography with fluorescence detection(HPLC-FLD) after immunoaffinity clean-up and was confirmed by liquid chromatography tandem mass spectrometry (LC-MS/MS). The limits of detection and quantification were 2.0 and 6.0µg/kg, respectively. The recovery ranged from 80.2%to 98.4% in the cereal based product. ZEA was detected in 38 samples (8.8% incidence), including 3 snack, 2 biscuit and33 other cereal products. The ZEA contamination levels were in the range of 5.38-53.76 µg/kg. Finally, LC-MS/MSanalysis of the contaminated samples was conducted to confirm the detected ZEA, and all 38 samples showing ZEA byHPLC-FLD were confirmed by LC-MS/MS.Keywords: mycotoxin, zearalenone, immunoaffinity column, cerealFusarium 속 곰팡이는 토양균류로서 자연계에 널리 분포하고있으며 그 중 몇 종은 식물병원균으로 벼의 Bakanae 병을 비롯하여 식물의 뿌리 섞음병, 줄기 섞음병, 잎마름병, 과실 부패병등을 일으킨다고 알려져 있다(1). 과거에는 이들 Fusarium 속 곰팡이는 주로 식물성 병원균으로만 취급되었지만 최근 zearalenone,deoxynivalenol, fumonisin 등 곰팡이독소를 생성하는 것으로 알려져 식품위생상 문제가 대두되고 있다(2-4). 곰팡이독소는 화학물질로 분류되지만 살아있는 생물로부터 생성되기 때문에 수확 전후 저장, 유통 등 여러 단계에서 발생할 수 있으므로 원료 생산에서 유통, 소비에 이르기까지 매우 중요한 위해요소로 작용한다. 또한 대부분의 곰팡이독소들은 물리적·화학적으로 안정한저분자 물질이기 때문에 세척 및 가열 등의 일반적인 가공조건으로는 제거되기 어렵다(5).이들 중 비스테로이드성 에스트로겐으로 알려진 제랄레논은Fusarium graminearum, Fusarium moniliforme 등에 의해 주로 생성되며 옥수수, 밀, 보리 등 농산물과 같이 탄수화물 함량이 높은 기질에서 잘 발생된다(6). 국제발암연구소(International Agencyfor Research on Cancer, IARC)는 제랄레논을 인체 발암성으로 분류할 수 없는 group 3로 분류하였지만 제랄레논은 체내에 흡수되면 대부분 배출되나 일부는 자궁, 고환, 난소 등에 전달되어 과에스트로렌증, 유산, 불임 등 생식에 관련된 독성을 유발하는 것으로 알려져 있다(7-9). Lee 등(10)의 보고에 따르면 제랄레논은동물의 에스트로겐에 영향을 주는 것으로 알려져 있고 에스트로겐에 영향을 주는 에스트로겐수용체는 핵의 사본에 달려있으며제랄레논에 의해 손상된 수용체는 쥐 유방조직에서 에스트로겐호르몬을 억제하는 것으로 나타났다. 그리고 제랄레논이 에스트로겐 반응 수용체를 포함하는 인간 유방암세포의 성장을 자극하는 것으로 보고하여 유방암 발생 가능성이 증가되고 있으며, 제랄레논은 구조적으로 estradiol과 유사한 구조로 estrogen 수용체와 결합함으로써 내분비교란 작용을 한다. 그 작용은 다른 환경내분비교란 물질인 polychrorinated biphenol(PCB)과 bisphenol A보다 강하다. 이에 유럽연합에서는 제랄레논의 식품 및 사료 중함량을 최저 20 mg/kg-최고 200 mg/kg으로 규격관리하고 있으며JECFA(The Joint FAO/WHO Export Committee on Food Addi-tives)에서는 잠정적 최대 허용 일일 섭취량(provisional maximumtolerable daily intake, PMTDI)을 0.5 mg/kg body weight/day로,유럽식품과학위원회(EU Scientific committee for food)에서는0.2 mg/kg body weight/day으로 제안하였다(11,12).제랄레논에 대한 국내외 연구보고는 오염가능성이 높은 식품군인 옥수수, 밀, 보리 등을 중심으로 조사되었다. 1999년 Placinta*Corresponding author: Mi-Ran Jang, Hazard Substances AnalysisTeam, Test & Analytical Center, Busan Regional KFDA, Busan 608-829, KoreaTel: 82-51-610-6181Fax: 82-51-610-6199E-mail: jang9797@hanmail.netReceived January 5, 2010; revised March 18, 2010;accepted December 12, 2010

Identification and structure elucidation of a p-phenoxybenzaldehyde in bamboo shoots by HPLC-ESI/MS/MS and NMR.

In this study, a derivative of p-phenoxybenzaldehyde in bamboo shoots was investigated. Bamboo shoots were ground and extracted with water, and an aqueous suspension was purified by SPE using Oasis HLB cartridges. After the SPE procedure, the analytes were analyzed by HPLC with refractive index detection (HPLC-RI). In the HPLC-RI analysis for sucralose, a putative sucralose was detected. In the subsequent HPLC-PDA analysis, the suspicious peak showed a unique UV absorption spectrum with the maximum wavelength at 285 nm indicating the existence of an aromatic ring. The contents of the unknown compound in bamboo shoot products ranged from 0.01 to 0.15 mg/g. The identity of the unknown compound was further confirmed by HPLC-ESI/MS/MS. The molecular weight of the unknown compound was determined to be 244. The chemical structure of the unknown compound was elucidated on the basis of NMR spectroscopic analyses ((1)H, (13)C, DEPT, COSY, HMQC, and HMBC). Finally, the structure of the unknown compound was characterized as 4-(4-dihydroxymethylphenoxy)benzaldehyde.

Transgenerational transfer of ADHD-like phenotypes in prenatally ethanol-exposed Sprague–Dawley rat offsprings

Ethanol exposure during gestational period can result in developmental, neurobehavioral and morphological abnormalities on offspring. We investigated whether maternal preconceptional ethanol intake shows ADHD-like phenotype in offspring rats. Sprague-Dawley female rats were treated with 6 g/kg/day ethanol for 10 days and mated with normal male rat at 8 weeks later. Litters were tested for their ADHD-like phenotypes using openfield, Y maze and electro-foot shock aversive water drinking test to screen behavioral abnormalities. Western blot and immunohistochemical staining were used to identify changes of dopamine and norepinephrine transporter in the brain. Offspring rats exposed to preconceptional ethanol displayed hyper-locomotive activity, attention deficit and impulsive behavior. The expression of dopamine transporter was inhibited in the striatum and also in cortex to a lesser extent. On the contrary, the expression of norepinephrine transporter was increased in the cortex and striatum. These results suggest that maternal preconceptional ethanol exposure induces ADHD-like behaviors and abnormal neural activities of catecholaminergic nervous system in SD rats.