Publications by authors named "Hyun Ok Ku"

Accumulating evidence indicates that chronic circadian rhythm disruption is associated with the development of neurodegenerative diseases induced by exposure to neurotoxic chemicals. Herein, we examined the relationship between cellular circadian rhythm disruption and cytotoxicity in neural cells. Moreover, we evaluated the potential application of an in vitro cellular circadian rhythm assay in determining circadian rhythm disruption as a sensitive and early marker of neurotoxicant-induced adverse effects.

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Background: Citric acid (CA) and sodium hypochlorite (NaOCl) have been used to disinfect animals to protect them against avian influenza and foot-and-mouth disease.

Objectives: We performed a good laboratory practice (GLP)-compliant animal toxicity study to assess the acute toxic effects of CA and NaOCl aerosol exposure in Sprague-Dawley rats.

Methods: Groups of five rats per sex were exposed for 4 h to four concentrations of the two chemicals, i.

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On September 27, 2012, an explosion from hydrofluoric acid occurred in Gumi city of Gyeongbuk province, Republic of Korea, exposing livestock animals nearby to Hydrofluoric acid (HF). This study aimed at evaluating the HF exposure among cattle raised near the accident site by determining the fluoride ion (F) levels and other biochemical parameters in the animals' urine and serum. The study groups included 90 cattle raised on farms near the accident site and, as controls, 21 cattle raised on a farm more than 100 km away from the accident site.

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Stem cell-based products (SCPs) are an emerging field of veterinary medicine that focuses on the regeneration, repair, or replacement of damaged tissues or organs. However, there are some issues in applying the traditional regulatory guideline for the approval of SCPs as veterinary medicinal products. This article describes the positions of Korea, US, and EU regarding SCPs, and compares the regulatory guidelines of each country for their safety evaluation.

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Background: Although previous studies explored urinary microRNA (miRNA), there is no agreement on nephrotoxicity-specific miRNA biomarkers.

Objectives: In this study, we assessed whether urinary miRNAs could be employed as biomarkers for nephrotoxicity.

Methods: For this, literature-based candidate miRNAs were identified by reviewing the previous studies.

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Circadian gene expression is defined by the gene-specific phase and amplitude of daily oscillations in mRNA and protein levels. D site-binding protein mRNA ( mRNA) shows high-amplitude oscillation; however, the underlying mechanism remains elusive. Here, we demonstrate that heterogeneous nuclear ribonucleoprotein K (hnRNP K) is a key regulator that activates transcription via the poly(C) motif within its proximal promoter.

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The D site-binding protein (Dbp) supports the rhythmic transcription of downstream genes, in part by displaying high-amplitude cycling of its own transcripts compared to other circadian-clock genes. However, the underlying mechanism remains elusive. Here, we demonstrated that the poly(C) motif within the proximal promoter, in addition to an E-box element, provoked transcriptional activation.

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Most living creatures have a circadian rhythm that is generated by a precisely regulated transcriptional-translational feedback loop of clock genes. Brain and muscle ARNT-like 1 (BMAL1) is one of the core clock genes and transcription factors that represents a positive arm of this autoregulatory circadian clock system. Despite the indispensable role of BMAL1 in the circadian rhythm, the molecular mechanisms underlying translational control of BMAL1 are largely unknown.

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With the increased use of cell therapy in the veterinary sector, there is a growing demand for the development of cell-based medicinal products and the determination of their safety. Currently, the Korean Animal and Plant Quarantine Agency has established a guideline for evaluating the safety of cell-based medicinal products for animal use. The guideline includes items related to definition, classification, management, manufacturing procedure and quality control (standard and test method), stability testing, toxicity testing, pharmacological testing, and performance of clinical trials.

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Acetylcholinesterase (AChE) activity level can be used as a diagnostic marker for anticholinesterase pesticide poisoning. In this study, we aimed to establish a baseline level of normal brain AChE activity in wild birds. AChE activity was measured in the brains of 87dead wild birds (26 species).

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prediction of hepatotoxicity can enhance the performance of non-clinical animal testing for identifying chemical hazards. In this study, we assessed high-content analysis (HCA) using multi-parameter cell-based assays as an hepatotoxicity testing model using various hepatotoxicants and human hepatocytes such as HepG2 cells and human primary hepatocytes (hPHs). Both hepatocyte types were exposed separately to multiple doses of ten hepatotoxicants associated with liver injury whose mechanisms of action have been described.

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Biofluid-based biomarkers provide an efficient tool for hazard identification of chemicals. Here, we explored the potential of microRNAs (miRNAs) as biomarkers for hepatotoxicity of chemicals by linking in vitro to in vivo animal models. A search of the literature identified candidate circulating miRNA biomarkers of chemical-induced hepatotoxicity.

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Introduction: Veterinarians use flumequine (FLU) widely but its toxicological effects are still unclear.

Material And Methods: FLU doses of 53, 200, or 750 mg/kg were administered orally for six weeks to pubertal male rats for evaluation of their toxicity.

Results: Weight gain was poorer after seven days of exposure to FLU 750, but relative weights of the brain, adrenal and thyroid glands, and testes were notably higher.

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Background: Pluripotent stem cells (PSCs) such as embryonic stem cells and induced pluripotent stem cells are promising target cells for cell regenerative medicine together with recently advanced technology of in-vitro differentiation. However, residual undifferentiated stem cells (USCs) during in-vitro differentiation are considered a potential risk for development of cancer cells and nonspecific lineage cell types. In this study we observed that USCs still exist during hepatic differentiation, consequently resulting in poor quality of the hepatic population and forming teratoma in vivo.

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Forty-one Enterococcus faecalis (E. faecalis) isolates from feces of pigs and chickens in Korea were screened for the presence of virulence factors. Gelatinase activity (85.

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Genomic analysis in the local lymph node assays (LLNAs) is useful for assessing skin sensitization of chemicals and providing insights into mechanisms of sensitization. In this study, we collected 1406 genes from previous microarray findings, validated changes in their expression by RT-PCR analysis in local lymph nodes draining skin exposed to different sensitizers, and interpreted their biological function through pathway-based genomic analysis, in which 468 genes were identified as being in the KEGG pathway database. The top-ranked functions (P < 0.

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Article Synopsis
  • * A new HPLC-diode array detection method was developed to accurately measure eugenol levels in clove, showing excellent precision and linearity in results.
  • * The study found significant variation in eugenol content among clove samples from different countries, confirming the method's effectiveness for quality and safety evaluation.
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Limb bud (LB) and central nerve system (CNS) cells were prepared from 12.5 day old pregnant female Crj:CD (SD) rats and treated with olaquindox and vitamin A. Cytotoxicity and inhibition on differentiation were measured in each cell.

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A total of 147 Enterococcus faecium and 165 Enterococcus faecalis isolates from fecal samples of chickens and pigs at slaughterhouses in Korea were tested for their resistance to 8 growth-promoting antimicrobials commonly used in animals and quinupristin and dalfopristin. Resistance to most antimicrobials was very common among both E. faecalis and E.

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Article Synopsis
  • Differentiating between skin irritation and sensitization is challenging due to similar clinical and biological responses, but additional data from gene expression and pathway analysis can provide clearer insights beyond standard tests.
  • The study exposed mice to various chemicals, including known sensitizers and a non-sensitizing irritant, and found that while all induced similar histological changes, specific gene expression patterns were notably different.
  • Key genes related to allergic inflammation, such as Oasl2 and Zbp1, were up-regulated in response to sensitizers but not to the irritant, suggesting that certain gene expressions could be used to effectively differentiate between skin sensitization and irritation.
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This study aimed to discover potential biomarkers for dioxynivalenol (DON) intoxication. B6C3F1 male mice were orally exposed to 0.83, 2.

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The murine local lymph node assay (LLNA) has been extensively utilized to evaluate sensitizing chemicals. However, there have been some concerns that its use to discriminate between classes of chemicals is minimal. It is thus desirable to identify better or alternative immune endpoints with in LLNA itself.

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There has been some concern that certain non-sensitizing irritants may yield false positive results in the murine local lymph node assay (LLNA). This study compared gene expression profiles in lymph nodes draining skin following exposure to sensitizers and irritants, to identify gene transcripts that could distinguish sensitizers from irritants. After treating CBA/N mouse ears for 3 days with the sensitizers 1-chloro-2,4-dinitrobenzene, 2-phenyl-4-ethoxymethylene-5-oxazolone, or toluene-2,4-diisocyanate or the non-sensitizing irritants croton oil or nonanoic acid, auricular lymph nodes and ear tissues were excised.

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Chlorpyrifos-methyl (CPM) suppressed androgenic activity in Hershberger assay using castrated rats. Acute oral lowest-observed-adverse-effect-level (LOAEL) and no-observed-adverse-effect-level (NOAEL) was evaluated as 12 and 0.1 mg/kg bw, respectively, based on its major effect of cholinesterase inhibition.

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Butylated hydroxyanisol (BHA) is a widely used antioxidant for long preservation of food products, cosmetics and pharmaceuticals. Although BHA is generally recognized as safe, it is classified as a suspected endocrine-disrupting compound. We investigated the effects of BHA on reproductive function and development by the treatment of mature male and female SD rats (F0) through pre-gestation, gestation and lactation period and of their offspring (F1) until 13 weeks old via gavage with BHA 0 (corn oil, vehicle control), 10, 100 and 500 mg/kg bw/day.

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