• Journal of Food Hygiene and Safety
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• v.38 no.5
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• pp.297-304
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• 2023

Domoic acid (DA), a neurotoxin produced naturally by diatoms, is responsible for incidents of amnesic shellfish poisoning. In this study, a modified analytical method was established to determine domoic acid in seafood using solid phase extraction cleanup and optimizing the amount of sample and extraction solvent to reduce interference effects. The modified method using high-performance liquid chromatography with ultraviolet detection was validated using three seafood matrices (mussel, red snow crab, and anchovy) at three concentrations (1, 2, and 4 mg/kg) and compared to the Food Code method. Compared to the Food Code method, the modified method showed better performance in terms of linearity (R²>0.999), detection limit (0.02-0.03 mg/kg), quantification limit (0.05-0.09 mg/kg), intra-/inter-day accuracy (86.2-100.4%), and intra-/inter-day precision (0.2-4.0%). Furthermore, the method was successfully applied for the analysis of 87 seafood samples marketed in Korea, and DA was detected at a low concentration of 140 ㎍/kg in one anchovy sample. These results suggest that the modified method can be used for routine determination of DA in seafood.

• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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• v.14 no.3
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• pp.163-170
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• 2009

Several species of the genus Pseudo-nitzschia produce the neurotoxin domoic acid (DA) known to be responsible for amnesic shellfish poisoning. In spite of the potentially toxic effects on marine ecosystem, even the representative Pseudo-nitzschia species occurring in Korean coastal waters have not been clearly reported. Plankton samples from several outer coastal sites of Tongyeong were collected fortnightly from May to November 2008 and the presence of diatoms of the genus Pseudo-nitzschia was examined using light and scanning electron microscopy. Thirteen species were observed, including P. americana, P. brasiliana, P. caciantha, P. calliantha, P. cuspidata, P. delicatissima, P. micropora, P. multiseries, P. multistriata, P. pseudodelicatissima, P. pungens, P. subfraudulenta, and P. subpacifica. The number of Pseudo-nitzschia species observed were only four in May, which was minimum during this survey, and then gradually increased attaining maximum, twelve, in September. After September it began to decrease again and got to five in November. Of these, P. americana, P. brasiliana, P. caciantha, P. calliantha, P. micropora, and P, pseudodelicatissima are new records for the Korean coastal waters and P. calliantha, P. cuspidata, P. delicatissima, P multiseries, P. multistriata, and P. pungens have been reported as DA producers around the world, but the potential toxicity of these species was not ascertained in Tongyeong area.

• Journal of Korean Neurosurgical Society
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• v.67 no.5
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• pp.510-520
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• 2024

Objective : Parkinson's disease (PD) is one of the most prevalent neurodegenerative diseases, characterized by the loss of dopaminergic neurons in the substantia nigra pars compacta. The treatment of PD aims to alleviate motor symptoms by replacing the reduced endogenous dopamine. Currently, there are no disease-modifying agents for the treatment of PD. Zebrafish (Danio rerio) have emerged as an effective tool for new drug discovery and screening in the age of translational research. The neurotoxin 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) is known to cause a similar loss of dopaminergic neurons in the human midbrain, with corresponding Parkinsonian symptoms. L-type calcium channels (LTCCs) have been implicated in the generation of mitochondrial oxidative stress, which underlies the pathogenesis of PD. Therefore, we investigated the neuro-restorative effect of LTCC inhibition in an MPTP-induced zebrafish PD model and suggested a possible drug candidate that might modify the progression of PD. Methods : All experiments were conducted using a line of transgenic zebrafish, Tg(dat:EGFP), in which green fluorescent protein (GFP) is expressed in dopaminergic neurons. The experimental groups were exposed to 500 μmol MPTP from 1 to 3 days post fertilization (dpf). The drug candidates : levodopa 1 mmol, nifedipine 10 μmol, nimodipine 3.5 μmol, diethylstilbestrol 0.3 μmol, luteolin 100 μmol, and calcitriol 0.25 μmol were exposed from 3 to 5 dpf. Locomotor activity was assessed by automated tracking and dopaminergic neurons were visualized in vivo by confocal microscopy. Results : Levodopa, nimodipine, diethylstilbestrol, and calcitriol had significant positive effects on the restoration of motor behavior, which was damaged by MPTP. Nimodipine and calcitriol have significant positive effects on the restoration of dopaminergic neurons, which were reduced by MPTP. Through locomotor analysis and dopaminergic neuron quantification, we identified the neuro-restorative effects of nimodipine and calcitriol in zebrafish MPTP-induced PD model. Conclusion : The present study identified the neuro-restorative effects of nimodipine and calcitriol in an MPTP-induced zebrafish model of PD. They restored dopaminergic neurons which were damaged due to the effects of MPTP and normalized the locomotor activity. LTCCs have potential pathological roles in neurodevelopmental and neurodegenerative disorders. Zebrafish are highly amenable to high-throughput drug screening and might, therefore, be a useful tool to work towards the identification of disease-modifying treatment for PD. Further studies including zebrafish genetic models to elucidate the mechanism of action of the disease-modifying candidate by investigating Ca2+ influx and mitochondrial function in dopaminergic neurons, are needed to reveal the pathogenesis of PD and develop disease-modifying treatments for PD.

• The Korean Journal of Pesticide Science
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• v.17 no.4
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• pp.264-270
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• 2013

Imidacloprid is a systemic insecticide which act as an insect neurotoxin. It used for control of pest such as aphids and other sucking insects in fruits and vegetables. Systemic pesticides move inside a crop following absorption by the plant, and these were converted into a variety of metabolites. Sometimes these metabolites make a problem about safety of agricultural products. So a simultaneous determination method of pesticide and its metabolites is needed, to monitor their presence in agricultural product and study on the fate of pesticide in a plant. This study's aim is to investigate simultaneous analysis method of imidacloprid and its metabolites, imidacloprid guanidine, imidacloprid olefin, imidacloprid urea, and 6-chloronicotinic acid in red pepper using QuEChERS method and LC-MS/MS systems. QuEChERS method was modifed beacuase $MgSO_4$ salts decreased the recoveries of 6-chloronicotinic acid in extraction procedure. Imidacloprid and its metabolites were extracted by acetonitrile with 1% glacial acetic acid and the extracts were purified through QuEChERS with primary secondary amine (PSA) and $C_{18}$ and analyzed with LC-MS/MS in ESI positive mode. Standard calibration curves were made by matrix matched standards and their correlation coefficients were higher than 0.999. Recovery studies were carried out on spiked pepper blank sample at four concentration levels (0.01, 0.04 and 0.1, 0.4 mg/kg). The average recoveries of imidacloprid and its metabolites were in the range of 70~120% with < 20% RSD. This result indicated that the method using QuEChERS and LC-MS/MS was suitable for the simultaneous determination of imidacloprid and its metabolites in red pepper.

• The Korean Journal of Pharmacology
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• v.19 no.2
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• pp.45-55
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• 1983

A role for brain serotonin(5-HT) in regulation of the HPA axis has been suggested but remains contoversial and poorly defined. The present experiments were designed to check kinetic parameters of 5-HT turnover in rat hypothalamus and remainder brain areas before and after stress and to test whether using various different pharmacologic approaches to stimulate or eliminate the control serotonergic system have any consistent effect on the stress-induced activation of HPA system. Steady state brain serotonin and 5-HIAA concentrations during 1 min ether stress were significantly elevated without significant rise in the levels of plasma corticosterone, which highly increased 2 minutes after stress. This suggests that the increase in serotonergic neuron activity precede that in HPA activity. Furthermore, during 1 ruin-ether stress or 30 min immobilization stress there is a marked increase in hypothalamic and remainder brain serotonin (5-HT) turnover or synthesis rates assessed by both the pargline/5-HT method and pargyline/5-HIAA method. The stress-induced corticosterone levels were increased by serotonin precursors and serotonin agonist in a dose-related fashion. The stress- induced corticosterone levels were highly elevated by L-tryptophan (100 mg/kg) and Potentiated by monoamine oxidase inhibitor, pargyline or serotonin agonist, 5-MeoDMT. The stress-induced elevation of corticosterone and 5-HT levels in rat brain were not significantly decreased by the administration of 5-HT synthesis inhibitor, PCPA and 5-HT neurotoxin, 5,7-DHT. However, the stress-induced elevation of corticosterone and 5-HT levels were decreased by the destruction of midline raphe nuclei. There was a strong positive correlation between plasma corticosterone and 5-HT concentrations changed by drugs which mainly manipulating 5-HT system in the hyhothalamus and in the remainder of the brain. In conclusion, our present data stongly suggest that 5-HT is an important key neurotransmitter involved in the stress-induced activation of the HPA system.

• Journal of Food Hygiene and Safety
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• v.27 no.1
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• pp.74-80
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• 2012

Fish contain both the neurotoxin methyl mercury (MeHg) and nutrients important for brain development. The developing brain appears to be most sensitive to MeHg toxicity and mothers who consume fish during pregnancy expose their fetus prenatally. Although brain development is most dramatic during fetal life, it continues for years postnatally and additional exposure can occur when a mother breast feeds or the child consumes fish. This raises the possibility that MeHg might influence brain. We evaluated the relationship between fish consumption and mercury exposure levels in umbilical cord blood of the pregnant women of the city of Tongyeong city, Korea. A total of 159 pregnant women residing in the city of Tongyeong, Korea were recruited for the study between October 2010 and March 2011. Fish consumption was evaluated using food frequency questionnaires including detailed questions on fish consumption. We used ANOVA to estimated the particular relevance between the frequency of fish consumption and the umbilical cord blood mercury concentration, and other various factors. The average mean concentration of mercury levels in umbilical cord blood of pregnant women who participated in our study were $2.69{\pm}2.50ppb$, ranging from 0.01 to 14.80 ppb. The mean concentration of umbilical cord blood mercury exposure was lower than the level recommended by WHO (5.0 ppb), but the mercury exposure level exceeded the WHO recommended in 17 (10.7%) cases of umbilical cord blood. Mercury levels in cord blood of pregnant women were $2.04{\pm}2.00ppb$, ranging from 0 to 8.00 ppb in below 29 years old and $3.18{\pm}2.74ppb$, ranging from 0.01 to 14.80 ppb in more 30 years old. In this study, there was a significant difference for the frequency of eating fish between the groups (p < 0.01). The level of the groups that ate fish 3 to more times per week ($4.15{\pm}4.02ppb$) was significant higher as compared with the level of other groups that ate fish 1 to times per week ($2.63{\pm}2.22ppb$) and none per week ($1.06{\pm}1.44ppb$), respectively. We found that the mercury concentration of umbilical cord blood associate with fish consumption and this was statistically significant and this fact revels that fish consumption is positively related to mercury levels in the umbilical cord blood. We need systematic and periodic research on the general population to prevent mercury poisoning, which can be cause by low-level mercury exposure from dietary intake such as chronic fish consumption.