• Journal of Microbiology and Biotechnology
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• 제18권1호
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• pp.118-123
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• 2008

A new method for antimicrobial susceptibility testing of vitro-cultured bacteria on an ordinary fluorescence spectrometer was developed. The viable bacteria reduced 3-(4,5 dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide (MTT) to produce insoluble particles that displayed intense resonance scattering light. The assay showed a linear relationship between the number of viable bacteria and the intensity of resonance scattering light. Dead bacteria were unable to reduce MTT. Methicillin-resistant Staphylococcus aureus exposed to flavonoids from Marchantia convoluta showed a flavonoids concentration-dependent inhibition of the ability to reduce MTT. In the assay, less than 12 h was required to attain susceptibility results and fewer bacteria were utilized than in traditional methods. The RLS technique could, in combination with the MTT assay, be a rapid and sensitive measuring method to determine the in vitro activity of new antimicrobials.

• International Journal of Stem Cells
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• 제17권2호
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• pp.182-193
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• 2024

To address the limitations of animal testing, scientific research is increasingly focused on developing alternative testing methods. These alternative tests utilize cells or tissues derived from animals or humans for in vitro testing, as well as artificial tissues and organoids. In western countries, animal testing for cosmetics has been banned, leading to the adoption of artificial skin for toxicity evaluation, such as skin corrosion and irritation assessments. Standard guidelines for skin organoid technology becomes necessary to ensure consistent data and evaluation in replacing animal testing with in vitro methods. These guidelines encompass aspects such as cell sourcing, culture techniques, quality requirements and assessment, storage and preservation, and organoid-based assays.

• Journal of Pharmaceutical Investigation
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• 제32권4호
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• pp.321-325
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• 2002

IVIVC (In vitro/in vivo correlation) is useful for predicting in vivo results from in vitro data. The aim of this study was to develop IVIVC of sustained release diltiazem. For this purpose, three types of diltiazem tablets with different in vitro dissolution rates were prepared. An in vitro dissolution testing method comprising of paddle apparatus, 50 rpm, water as dissolution medium was developed. Under these condition, we demonstrated that AUCinf could be predicted by evaluating $d_{70%}$ (time dissolved 70%) in vitro since the in vivo AUCinf was correlated with the in vitro $d_{70%}$ (r=-0.9981).

• Journal of the Society of Cosmetic Scientists of Korea
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• 제26권1호
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• pp.17-40
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• 2000

Cytotoxicity assays using artificial skins have been proposed as in vitro alternatives to minimize animal ocular and dermal irritation testing. Accordingly, the responses of artificial skins to the well-characterized chemical irritants toluene, glutaraldehyde, and sodium lauryl sulfate (SLS), and the nonirritant polyethylene glycol were studied. The evaluation of the irritating and non-irritating test chemicals was also compared with the responses observed in human dermal fibroblasts and human epidermal keratinocytes grown in a monolayer culture. The responses monitored included an MTT mitochondrial functionality assay. In order to better understand the local mechanisms involved in skin damage and repair, the production of several mitogenic proinflammatory mediators, interleukin-l$\alpha$, 12-HETE, and 15-HETE, was also investigated. Dose-dependent increases in the levels of かIn and the HETEs were observed in the underlying medium of the skin systems exposed to the two skin irritants, glutaraldehyde and SLS. The results of the present study show that both human artificial skins can be used as efficient in vitro testing models for the evaluation of skin toxicity and for screening contact skin irritancy.

• International Journal of Stem Cells
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• 제17권2호
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• pp.120-129
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• 2024

Recent amendments to regulatory frameworks have placed a greater emphasis on the utilization of in vitro testing platforms for preclinical drug evaluations and toxicity assessments. This requires advanced tissue models capable of accurately replicating liver functions for drug efficacy and toxicity predictions. Liver organoids, derived from human cell sources, offer promise as a reliable platform for drug evaluation. However, there is a lack of standardized quality evaluation methods, which hinders their regulatory acceptance. This paper proposes comprehensive quality standards tailored for liver organoids, addressing cell source validation, organoid generation, and functional assessment. These guidelines aim to enhance reproducibility and accuracy in toxicity testing, thereby accelerating the adoption of organoids as a reliable alternative or complementary tool to animal testing in drug development. The quality standards include criteria for size, cellular composition, gene expression, and functional assays, thus ensuring a robust hepatotoxicity testing platform.

• Molecular & Cellular Toxicology
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• 제3권2호
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• pp.113-118
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• 2007

Chlorobenzenes due to their acute toxicity and the capability of bioaccumulating are of great health and environmental concern. Especially, 1, 2-dichlorobenzene (CAS No. 95-50-1) is used for organic synthesis, dye manufacture, as a solvent and for other applications in chemical industry. Adverse effects of 1, 2-dichlorobenzene includes increases in liver and kidney weights and hepatotoxicity. In this study, we evaluated the genetic toxicity of 1, 2-dichlorobenzene with more advanced methods, in vitro mouse lymphoma assay $tk^{+/-}$ gene assay (MLA) and in vitro mouse supravital micronucleus (MN) assay. 1, 2-Dichlorobenzene appeared the significantly positive results and the induction of large mutant colonies only in the presence of metabolic activation system with MLA. But in vitro testing of 1, 2-dichlorobenzene yielded negative results with supravital MN assay. These results suggest that 1, 2-dichlorobenzene may play a mutagen rather than clastogen in vitro mammalian system.

• Health Policy and Management
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• 제33권2호
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• pp.173-184
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• 2023

Background: The coronavirus disease 2019 pandemic has been challenging the healthcare service, i.e., the vitalization of the point of care accompanying self-testing in vitro diagnostic medical devices (IVDs). This study aims to suggest priority criteria to classify self-testing IVDs using the analytic hierarchy process technique. Methods: Two dimensions of the characteristics embedded in the IVDs and the diseases to be diagnosed with self-testing IVDs were parallelly considered and independently investigated. In addition, three expert panels consisting of laboratory medical doctors (n=11), clinicians (n=10), and citizens (n=11) who have an interest in the selection of self-testing IVDs were asked to answer to questionnaires. Priorities were derived and compared among each expert panel. Results: First of all, ease of specimen collection (0.241), urgency of the situation (0.224), and simplicity of device operation (0.214) were found to be the most important criteria in light of the functional characteristics of self-testing IVDs. Medical doctors valued the ease of specimen collection, but the citizen's panel valued self-management of the disease more. Second, considering the characteristics of the diseases, the priority criteria were shown in the order of prevalence of diseases (0.421), fatality of disease (0.378), and disease with stigma (0.201). Third, medical doctors responded that self-testing IVDs were more than twice as suitable for non-communicable diseases as compared to communicable diseases (0.688 vs. 0.312), but the citizen's group responded that self-testing IVDs were slightly more suitable for infectious diseases (0.511 vs. 0.489). Conclusion: Our findings suggested that self-testing IVDs could be primarily classified as the items for diagnosis of non-communicable diseases for the purpose of self-management with easy specimen collection and simple operation of devices, taking into account the urgency of the situation as well as prevalence and fatality of the disease.

• Clinical and Experimental Reproductive Medicine
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• 제51권1호
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• pp.75-84
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• 2024

Objective: The purpose of this study was to evaluate the impact of preimplantation genetic testing for aneuploidy (PGT-A) on clinical outcomes among high-risk patients. Methods: This retrospective study involved 1,368 patients and the same number of cycles, including 520 cycles with PGT-A and 848 cycles without PGT-A. The study participants comprised women of advanced maternal age (AMA) and those affected by recurrent implantation failure (RIF), recurrent pregnancy loss (RPL), or severe male factor infertility (SMF). Results: PGT-A was associated with significant improvements in the implantation rate (IR) and the ongoing pregnancy rate/live birth rate (OPR/LBR) per embryo transfer cycle in the AMA (39.3% vs. 16.2% [p<0.001] and 42.0% vs. 21.8% [p<0.001], respectively), RIF (41.7% vs. 22.0% [p<0.001] and 47.0% vs. 28.6% [p<0.001], respectively), and RPL (45.6% vs. 19.5% [p<0.001] and 49.1% vs. 24.2% [p<0.001], respectively) groups, as well as the IR in the SMF group (43.3% vs. 26.5%, p=0.011). Additionally, PGT-A was associated with lower overall incidence rates of early pregnancy loss in the AMA (16.7% vs. 34.3%, p=0.001) and RPL (16.7% vs. 50.0%, p<0.001) groups. However, the OPR/LBR per total cycle across all PGT-A groups did not significantly exceed that for the non-PGT-A groups. Conclusion: PGT-A demonstrated beneficial effects in high-risk patients. However, our findings indicate that these benefits are more pronounced in carefully selected candidates than in the entire high-risk patient population.

• The Korean Journal of Physiology and Pharmacology
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• 제24권6호
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• pp.441-452
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• 2020

In vivo animal models are limited in their ability to mimic the extremely complex systems of the human body, and there is increasing disquiet about the ethics of animal research. Many authorities in different geographical areas are considering implementing a ban on animal testing, including testing for cosmetics and pharmaceuticals. Therefore, there is a need for research into systems that can replicate the responses of laboratory animals and simulate environments similar to the human body in a laboratory. An in vitro two-dimensional cell culture model is widely used, because such a system is relatively inexpensive, easy to implement, and can gather considerable amounts of reference data. However, these models lack a real physiological extracellular environment. Recent advances in stem cell biology, tissue engineering, and microfabrication techniques have facilitated the development of various 3D cell culture models. These include multicellular spheroids, organoids, and organs-on-chips, each of which has its own advantages and limitations. Organoids are organ-specific cell clusters created by aggregating cells derived from pluripotent, adult, and cancer stem cells. Patient-derived organoids can be used as models of human disease in a culture dish. Biomimetic organ chips are models that replicate the physiological and mechanical functions of human organs. Many organoids and organ-on-a-chips have been developed for drug screening and testing, so competition for patents between countries is also intensifying. We analyzed the scientific and technological trends underlying these cutting-edge models, which are developed for use as non-animal models for testing safety and efficacy at the nonclinical stages of drug development.

• Toxicological Research
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• 제33권2호
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• pp.107-118
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• 2017

Although alternative test methods based on the 3Rs (Replacement, Reduction, Refinement) are being developed to replace animal testing in reproductive and developmental toxicology, they are still in an early stage. Consequently, we aimed to develop alternative test methods in male animals using mouse spermatogonial stem cells (mSSCs). Here, we modified the OECD TG 489 and optimized the in vitro comet assay in our previous study. This study aimed to verify the validity of in vitro tests involving mSSCs by comparing their results with those of in vivo tests using C57BL/6 mice by gavage. We selected hydroxyurea (HU), which is known to chemically induce male reproductive toxicity. The 50% inhibitory concentration ($IC_{50}$) value of HU was 0.9 mM, as determined by the MTT assay. In the in vitro comet assay, % tail DNA and Olive tail moment (OTM) after HU administration increased significantly, compared to the control. Annexin V, PI staining and TUNEL assays showed that HU caused apoptosis in mSSCs. In order to compare in vitro tests with in vivo tests, the same substances were administered to male C57BL/6 mice. Reproductive toxicity was observed at 25, 50, 100, and 200 mg/kg/day as measured by clinical measures of reduction in sperm motility and testicular weight. The comet assay, DCFH-DA assay, H&E staining, and TUNEL assay were also performed. The results of the test with C57BL/6 mice were similar to those with mSSCs for HU treatment. Finally, linear regression analysis showed a strong positive correlation between results of in vitro tests and those of in vivo. In conclusion, the present study is the first to demonstrate the effect of HU-induced DNA damage, ROS formation, and apoptosis in mSSCs. Further, the results of the current study suggest that mSSCs could be a useful model to predict male reproductive toxicity.