• Title/Summary/Keyword: repeated exposure

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Changes of Amino Acid Neurotransmitter Contents in Rat Brain by Toluene Inhalation (톨루엔 흡입이 뇌내 아미노산 신경전달물질 함량에 미치는 영향)

  • 이선희;신대섭;김부영
    • Biomolecules & Therapeutics
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    • v.3 no.1
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    • pp.91-96
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    • 1995
  • The effects of toluene inhalation on the contents of amino acid neurotransmitters in rat brain were investigated and blood toluene concentrations inducing changes of behavior and amino acid neurotransmitter contents in rat brain were observed. Male wistar rats were exposed to toluene vapor (single dose : 1700, 5000 and 10000 ppm for 2 hrs, repeated dose : 1700 and 5000 ppm for 2 hrs/day$\times$6 days). Toluene concentrations in blood and the inhalation chamber were assayed by GC with headspace sampler. HPLC method following PITC derivatization was used to measure the amino acid contents in brain tissues such as frontal cortex, caudate, hippocampus, cerebellum and brain stem. Glutamic acid and aspartic acid levels were increased by single inhalation of toluene (5000 ppm) in all the brain areas assayed in this experiment. In caudate and cerebellum, taurine levels were decreased by single inhalation of low dose toluene (1700 ppm), but increased by repeated administration. At high blood toluene concentration, GABA levels were increased in all the brain areas assayed in this experiment and the increasing extents of inhibitory amino acid contents measured in caudate and hippocampus were greater than those of excitatory amino acids. These results suggest that the changes of amino acid neurotransmitter contents in brain by exposure to toluene may modulate toluene-induced behaviors.

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Neurobiological Effects of Methamphetamine Abuse on Neurotransmitters: A Review (흥분제(Psychostimulants)에 대한 신경생물학 측면의 고찰 -Methamphetamine 남용을 중심으로)

  • Lee Tae Kyung;Jon E. Grant;Kim, Suck Won;Oh Dong Yul
    • Journal of The Korean Society of Clinical Toxicology
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    • v.1 no.1
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    • pp.21-26
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    • 2003
  • Methamphetamine (MA) is a major drug of abuse in Korea. Currently preliminary evidence suggests that MA dependence may cause long-term neural damage in human. Repeated exposure to psychostimulants such as methamphetamine results in behavioral sensitization, a paradigm thought to be relevant to drug craving and addiction in human. Sensitization alters neural circuitry involved in normal processes of incentrive, motivation, and reward. However the precise mechanism of this behavioral sensitization has not yet been fully elucidated. Repeated use of high dose MA causes neurotoxicity which is characterized by a long-lasting depletion of striatal dopamine (DA) and tyrosin hydroxylase activity of DA, DA-transporter binding sites in the striatum. The loss of DA transporters correlates with memory problems and lack of motor coordination. DA fuels motivation and pleasure, but it' s also crucial for learning and movement. This selective review provides a summary of studies that assess the neurobiological mechanisms of MA.

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Electrical Properties of Ag-coated Conductive Yarns Depending on Physical and Chemical Conditions (물리화학적 조건에 따른 은코팅 전도사의 전기적 특성)

  • Ryu, Jong-Woo;Jee, Young-Joo;Kim, Hong-Jae;Kwon, Seo-Yoon;Yoon, Nam-Sik
    • Textile Coloration and Finishing
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    • v.23 no.1
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    • pp.43-50
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    • 2011
  • Electrically conductive yarn coated with silver particles are widely used to make smart wear but recent studies on smart fabrics are focused on measuring method of electrical characteristics and improving technologies of its electric properties. Also durability of conductive yarn with environmental change was also important work to make smart fabric. We compared resistance changes of silver coated conductive yarns under various physical and chemical conditions such as repeated strain, heat exposure and pH for basic informations on smart wear manufacturing process. And we deduct that repeated strain among the physical conditions was most effective factors on yarn resistance change and the low resistance change was observed with increasing the number of filaments in identical yarn fineness.

Comparative Study for Estimating Vaccine Efficacy in Vaccine Research under Heterogeneity (이질적 환경을 가지는 백신연구에서 백신효과 추정 방법의 비교연구)

  • Lee, Soo-Young;Lee, Jae-Won
    • Communications for Statistical Applications and Methods
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    • v.17 no.2
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    • pp.231-239
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    • 2010
  • In vaccine research, proportional hazards model including only first event have been widely used for estimating vaccine efficacy because it is easy to interpret and convenient. However, this method causes not only loss of information but also biased result when heterogeneity of study subject in exposure and susceptibility exists. Furthermore, it is hard to ignore the possibility that each event is correlated with each other in the repeated events. Therefore, we compare various statistical models to estimate vaccine efficacy under various situations with heterogeneity and event dependency.

A Study on Color Reliability of New Combat Uniform Fabrics through Quantitative Analysis of the Color and Color Fastness to Washing (색상 및 세탁견뢰도의 정량적 분석을 통한 신형 전투복 원단의 색상신뢰성 연구)

  • Hong, Seong-don;Kim, Byung-Soon;Jang, Yeonju;Lee, Jung Soon
    • Journal of the Korean Society of Clothing and Textiles
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    • v.40 no.3
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    • pp.456-464
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    • 2016
  • A new combat uniform is improved for added combat safety with various functions such as survivability, battle conformity and a camouflage performance system. Camouflage performance is an important factor in terms of combat survivability since it makes identification difficult and provide security. The combat uniform is worn under extreme conditions (exposure to ultraviolet light, sweat and friction) and an excellent color fastness to repeated washing is required. In this study, we investigated the color management, durability and discoloration of new combat uniform fabric with a digital pattern for camouflage performance to provide preliminary color management data. We examined color differences between standard fabric and mass-produced combat uniform fabrics, color differences between each military supply contract firm and color changes in combat uniforms after 60 washing cycles. The slight color differences between standard fabric and mass-produced combat uniform fabrics were tolerable under quality criteria of Republic of Korea Ministry of National Defense. However, the differences between the military supply contract firms were recognizable to the naked eye and increased with repeated washing. Continuous research on color fastness under repeated washing and color management is required to standardize reliability from each military supply contract firm for the daytime performance of a combat uniform's camouflage.

Alterations in Striatal Circuits Underlying Addiction-Like Behaviors

  • Kim, Hyun Jin;Lee, Joo Han;Yun, Kyunghwa;Kim, Joung-Hun
    • Molecules and Cells
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    • v.40 no.6
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    • pp.379-385
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    • 2017
  • Drug addiction is a severe psychiatric disorder characterized by the compulsive pursuit of drugs of abuse despite potential adverse consequences. Although several decades of studies have revealed that psychostimulant use can result in extensive alterations of neural circuits and physiology, no effective therapeutic strategies or medicines for drug addiction currently exist. Changes in neuronal connectivity and regulation occurring after repeated drug exposure contribute to addiction-like behaviors in animal models. Among the involved brain areas, including those of the reward system, the striatum is the major area of convergence for glutamate, GABA, and dopamine transmission, and this brain region potentially determines stereotyped behaviors. Although the physiological consequences of striatal neurons after drug exposure have been relatively well documented, it remains to be clarified how changes in striatal connectivity underlie and modulate the expression of addiction-like behaviors. Understanding how striatal circuits contribute to addiction-like behaviors may lead to the development of strategies that successfully attenuate drug-induced behavioral changes. In this review, we summarize the results of recent studies that have examined striatal circuitry and pathway-specific alterations leading to addiction-like behaviors to provide an updated framework for future investigations.

Acute Hepatotoxicity and Toxicokinetics of Acetaminophen in Mice (마우스에서 아세트아미노펜의 급성간독성과 독물동태학)

  • 서경원;류정상;김효정
    • Toxicological Research
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    • v.13 no.3
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    • pp.237-245
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    • 1997
  • As the development of a pharmaceutical product is a dynamic process which involves continuousfeed-back between non-clinical and clinical studies, the integration of pharmacokinetics into toxicity testing became increasingly important in recent years. Toxicokinetic measurements in the toxicity studies is considered to be an important scientific approach in the interpretation of the toxicology findings and the promotion of rational study design development. Primarily this research project was conducted to determine the systemic exposure achieved in acute toxicity test and its relationship to dose level and the time course of the toxicity study. Acute hepatotoxicity study and its relevant toxicokinetic study in mice were performed using acetarninophen (AA) as a model compound. The correlation between acute hepatotoxicity indices and toxicokinetic parameters following intraperitoneally administration of various dosages of AA in mice was evaluated and discussed minutely in the text. Based on these studies, single-dose toxicity testing of AA including kinetic studies was evaluated in ICR mice for 7 days and interpreted in the text. Our results from the integration of toxicokinetic monitoring into single-dose toxicity study enable to elucidate the relation of the exposure achieved in toxicity study to toxicological findings and assist in the selection of appropriate dose levels for use in repeated-dose toxicity or later studies.

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Flow Characteristics Analysis for the Chemical Decontamination of the Kori-1 Nuclear Power Plant

  • Cho, Seo-Yeon;Kim, ByongSup;Bang, Youngsuk;Kim, KeonYeop
    • Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
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    • v.19 no.1
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    • pp.51-58
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    • 2021
  • Chemical decontamination of primary systems in a nuclear power plant (NPP) prior to commencing the main decommissioning activities is required to reduce radiation exposure during its process. The entire process is repeated until the desired decontamination factor is obtained. To achieve improved decontamination factors over a shorter time with fewer cycles, the appropriate flow characteristics are required. In addition, to prepare an operating procedure that is adaptable to various conditions and situations, the transient analysis results would be required for operator action and system impact assessment. In this study, the flow characteristics in the steady-state and transient conditions for the chemical decontamination operations of the Kori-1 NPP were analyzed and compared via the MARS-KS code simulation. Loss of residual heat removal (RHR) and steam generator tube rupture (SGTR) simulations were conducted for the postulated abnormal events. Loss of RHR results showed the reactor coolant system (RCS) temperature increase, which can damage the reactor coolant pump (RCP)s by its cavitation. The SGTR results indicated a void formation in the RCS interior by the decrease in pressurizer (PZR) pressure, which can cause surface exposure and tripping of the RCPs unless proper actions are taken before the required pressure limit is achieved.

Impedance Changes of Living Tissue During Radiation Exposure Dose (방사선 피폭선량에 대한 생체 조직의 임피던스 변화)

  • Kil, Sang Hyeong;Lee, Moo Seok;Nam, Ji Ho;Lee, Yeong Hwa;Kim, Gun Do;Lee, Jong Kyu
    • Journal of Radiation Protection and Research
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    • v.38 no.4
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    • pp.202-207
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    • 2013
  • Bioimpedance involves a lot of information related to living tissue. If there is alteration in bio tissue, its electrical characteristics also change. It is to study electrical characteristics of pork tenderlion in using a HP-4194A Impedance/Gain-phase analyzer instrument and electrical characteristics changes by graded radiation exposure dose. The results were as follow 1. Electrical characteristics of pork tenderlion in repeated measurement had high precision within ${\pm}5$% of coefficiency of variability. 2. During the measurement impedance absolute value and phase alteration did not show statistically significant difference.(p>0.05) 3. While impedance phase of electrical characteristics associated with frequency change was almost stable, impedance absolute value was in inverse proportion to frequency that means high inverse correlation of -0.096(r). 4. Impedance absolute value dropped in radiation exposure dose. The alteration of the value did not show statistically significant difference in 1 Gy, 2 Gy and 4 Gy.(p>0.05) However in radiation exposure dose of 10 Gy, the decrease of impedance absolute value was significantly different.(p<0.05) 5. Impedance phase according to radiation exposure dose change did not show statistically significant difference in 1 Gy, 2 Gy, 4 Gy, and 10 Gy(p>0.05).

Basic Physiological Research on the Wing Flapping of the Sweet Potato Hawkmoth Using Multimedia

  • Nakajima, Isao;Yagi, Yukako
    • Journal of Multimedia Information System
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    • v.7 no.2
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    • pp.189-196
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    • 2020
  • We have developed a device for recording biological data by inserting three electrodes and a needle with an angular velocity sensor into the moth for the purpose of measuring the electromyogram of the flapping and the corresponding lift force. With this measurement, it is possible to evaluate the moth-physiological function of moths, and the amount of pesticides that insects are exposed to (currently LD50-based standards), especially the amount of chronic low-concentration exposure, can be reduced the dose. We measured and recorded 2-channel electromyography (EMG) and angular velocity corresponding to pitch angle (pitch-like angle) associated with wing flapping for 100 sweet potato hawkmoths (50 females and 50 males) with the animals suspended and constrained in air. Overall, the angular velocity and amplitude of EMG signals demonstrated high correlation, with a correlation coefficient of R = 0.792. In contrast, the results of analysis performed on the peak-to-peak (PP) EMG intervals, which correspond to the RR intervals of ECG signals, indicated a correlation between ΔF fluctuation and angular velocity of R = 0.379. Thus, the accuracy of the regression curve was relatively poor. Using a DC amplification circuit without capacitive coupling as the EMG amplification circuit, we confirmed that the baseline changes at the gear change point of wing flapping. The following formula gives the lift provided by the wing: angular velocity × thoracic weight - air resistance - (eddy resistance due to turbulence). In future studies, we plan to attach a micro radio transmitter to the moths to gather data on potential energy, kinetic energy, and displacement during free flight for analysis. Such physiological functional evaluations of moths may alleviate damage to insect health due to repeated exposure to multiple agrochemicals and may lead to significant changes in the toxicity standards, which are currently based on LD50 values.