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result(s) for
"Kim, Hyeon Ah"
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Synthesis of bulk nanostructured Mg-based alloy via spark plasma sintering through in situ crystallization of an amorphous precursor
2021
We present the synthesis of a bulk nanostructured Mg-based alloy that has a grain size less than 300 nm. A nanostructured Mg-Zn-Cu-Nd alloy with an exceptionally high hardness can be obtained through simultaneous consolidation and in situ crystallization of the amorphous Mg 84 Zn 7 Cu 3 Nd 6 alloy precursor using the spark plasma sintering process. We evaluate the relationship between the microstructure and preparation conditions on the grain size of nanostructured Mg-based alloys during the sintering process. The hardness of the bulk sample produced from the sintered amorphous Mg-Zn-Cu-Nd precursor at 260 °C is maximized via the nanocrystallization of intermetallic compounds using the sintering process. The populated crystallization and confined growth of phases contribute to the refinement of gains in nanostructured Mg-based alloys.
Journal Article
Korean National Oral Health Survey Data on the Symmetry of Primary Dentition Surface Caries
2018
This study evaluated the intraoral symmetry of dental caries in primary teeth as part of a study of caries patterns in primary dentition.
The data for 4,800 5-year-old and 4,379 8-year-old children in this study were from the 2012 Korean national oral health survey. Pearson correlation coefficients of the decayed and filled surface (dfs) values ranged from 0.436 (lower primary canines) to 0.835 (upper primary central incisors) for the right and left primary teeth and from 0.084 (right primary central incisor) to 0.457 (left primary second molar) for the upper and lower primary dentition (P< 0.01).
The upper and lower dfs values differed significantly (P< 0.05) when the right and left primary second molars were excluded. The left or right primary data without caries ranged from 56.4% (lower of first and second primary molars) to 99.7% (lower primary central incisors). The bilateral caries among cases with one or more in the right or left primary teeth ranged from 25.0% (lower lateral primary incisor) to 72.7% (upper primary central incisors).
These results suggested that dental caries in primary teeth show bilateral symmetry and differences in the degree of symmetry according to the teeth set or surface set of the homologous teeth.
Journal Article
Caries Prevalence in Korean Children and Adolescents from 2000 to 2012
2017
Objectives: National oral health data is required to assess a population's oral health needs, monitor oral health, plan effective intervention community programs and health policies, and evaluate progress toward health objectives. The study aimed to estimate the prevalence, severity, and inequality in dental caries distribution among Korean young people. Study Design: Trained, calibrated examiners at the Korea Ministry of Health & Welfare conducted epidemiological surveys in 2000, 2006, and 2012 during which dental caries were assessed according to World Health Organization (WHO) diagnostic criteria. Decayed, missing, and filled surface and tooth (DMFS/DMFT) indices were estimated. Results: DMFT indices decreased in all regions between 2000 and 2012, with values of 3.3, 2.2, and 1.8 for 12-year-old children in 2000, 2006, and 2012, respectively. The prevalence of caries was higher among female versus male subjects and in rural versus urban areas. Conclusions: Despite the observed decrease in caries experience indicators in Korea, the caries prevalence remains considerably higher than that in European countries and than the targets set by WHO within the Health21 policy framework. Therefore, Korea apparently retains further potential for caries reduction. Community-based oral disease prevention programs are urgently needed to promote oral health.
Journal Article
Combined inhibition of Bcl-2 family members and YAP induces synthetic lethality in metastatic gastric cancer with RASA1 and NF2 deficiency
by
Kim, Dae-Yong
,
An, Hyeok-Won
,
Seok, Sang Hyeok
in
Animal models
,
Bcl-2 protein
,
Bcl-x protein
2023
Background
Targetable molecular drivers of gastric cancer (GC) metastasis remain largely unidentified, leading to limited targeted therapy options for advanced GC. We aimed to identify molecular drivers for metastasis and devise corresponding therapeutic strategies.
Methods
We performed an unbiased in vivo genome-wide CRISPR/Cas9 knockout (KO) screening in peritoneal dissemination using genetically engineered GC mouse models. Candidate genes were validated through in vivo transplantation assays using KO cells. We analyzed target expression patterns in GC clinical samples using immunohistochemistry. The functional contributions of target genes were studied through knockdown, KO, and overexpression approaches in tumorsphere and organoid assays. Small chemical inhibitors against Bcl-2 members and YAP were tested in vitro and in vivo
.
Results
We identified
Nf2
and
Rasa1
as metastasis-suppressing genes through the screening. Clinically,
RASA1
mutations along with low
NF2
expression define a distinct molecular subtype of metastatic GC exhibiting aggressive traits. NF2 and RASA1 deficiency increased in vivo metastasis and in vitro tumorsphere formation by synergistically amplifying Wnt and YAP signaling in cancer stem cells (CSCs). NF2 deficiency enhanced Bcl-2-mediated Wnt signaling, conferring resistance to YAP inhibition in CSCs. This resistance was counteracted via synthetic lethality achieved by simultaneous inhibition of YAP and Bcl-2. RASA1 deficiency amplified the Wnt pathway via Bcl-xL, contributing to cancer stemness.
RASA1
mutation created vulnerability to Bcl-xL inhibition, but the additional NF2 deletion conferred resistance to Bcl-xL inhibition due to YAP activation. The combined inhibition of Bcl-xL and YAP synergistically suppressed cancer stemness and in vivo metastasis in RASA1 and NF2 co-deficiency.
Conclusion
Our research unveils the intricate interplay between YAP and Bcl-2 family members, which can lead to synthetic lethality, offering a potential strategy to overcome drug resistance. Importantly, our findings support a personalized medicine approach where combined therapy targeting YAP and Bcl-2, tailored to NF2 and RASA1 status, could effectively manage metastatic GC.
Journal Article
High strength nanostructured Al-based alloys through optimized processing of rapidly quenched amorphous precursors
by
Park, Gyu-Hyeon
,
Kim, Do-Hyang
,
Eckert, Jürgen
in
639/301/1023/1026
,
639/301/1023/218
,
Alloys
2018
We report the methods increasing both strength and ductility of aluminum alloys transformed from amorphous precursor. The mechanical properties of bulk samples produced by spark-plasma sintering (SPS) of amorphous Al-Ni-Co-Dy powders at temperatures above 673 K are significantly enhanced by
in-situ
crystallization of nano-scale intermetallic compounds during the SPS process. The spark plasma sintered Al
84
Ni
7
Co
3
Dy
6
bulk specimens exhibit 1433 MPa compressive yield strength and 1773 MPa maximum strength together with 5.6% plastic strain, respectively. The addition of Dy enhances the thermal stability of primary fcc Al in the amorphous Al-TM -RE alloy. The precipitation of intermetallic phases by crystallization of the remaining amorphous matrix plays important role to restrict the growth of the fcc Al phase and contributes to the improvement of the mechanical properties. Such fully crystalline nano- or ultrafine-scale Al-Ni-Co-Dy systems are considered promising for industrial application because their superior mechanical properties in terms of a combination of very high room temperature strength combined with good ductility.
Journal Article
Entamoeba muris provides a mouse model for amoebic colitis pathology characterized by T cell associated colonization
2025
Entamoeba (E.) histolytica
is a major global health concern as the causative agent of amoebic colitis, yet research is hindered by the lack of an ideal animal model. While
E. muris
has been traditionally considered non-pathogenic, our study demonstrates that it induces a colitis-like pathology in BALB/c mice, making it a promising model for studying
E. histolytica
infection. Using a fecal-oral infection route, we confirmed successful
E. muris
colonization, leading to colonic inflammation characterized by early CD4 + T-cell infiltration and FOXP3 + regulatory T-cell recruitment. We further demonstrate that T-cell immunity is essential for
E. muris
colonization, as T-cell-depleted BALB/c mice and T-cell-deficient BALB/c nude mice failed to support persistent infection. Additionally, infection disrupts epithelial homeostasis, impairing goblet cell generation, and induces significant shifts in gut microbiota composition, notably reducing beneficial Firmicutes species. Collectively, these findings demonstrate that
E. muris
infection induces inflammation and microbiota alterations, mirroring critical aspects of amoebic colitis, reinforcing its value as a model for studying
E. histolytica
pathogenesis and host–parasite interactions.
Journal Article
Oropharyngeal Airway Three-dimensional Changes after Treatment with Myobrace in Class II Retrognathic Children
2017
Since cephalometric radiography was introduced by Broadbent to evaluate the craniofacial morphology, as recently reported (8), to evaluate the size of the airways and tongue in patients with sleep apnea, it is widely used, but, not be evaluated in three dimensions. Additional studies are necessary for objective improvements of symptoms of sleep disorders using polysomnography after applying Myobrace to the patients diagnosed with OSA. Since we obtained airway expansion using Myobrace, we suggest it is used for myofunctional orthodontic treatment of childhood OSAS patients.
Journal Article
Oropharyngeal Airway Dimensional Changes after Treatment with Trainer for Kids (T4K) in Class II Retrognathic Children
by
Park, So-Young
,
Hong, Kee-Sang
,
Kim, Ah-Hyeon
in
Airway management
,
Letter to the Editor
,
Mouth
2016
In the case of class II malocclusion where maxillary teeth show labial inclination and mandible shows retreat, by using Myobrace (T4K(TM)), mandibular position can be moved to the front using maxillary anterior teeth as an anchorage and thus gains the improving effect of the axial angle, excessively labial inclined, of maxillary anterior teeth to palatal area and therefore, expansion of upper airway can be achieved(Figure 1). [...]in the case of Activator, Bionator and FR-2 device generally used for class II malocclusion in mixed dentition, the cooperation level of childhood patients is usually low due to their big size and additional education on muscle function is necessary for correcting the location of tongue and mouth respiration.
Journal Article
Restoration of Strip Crown with a Resin-Bonded Composite Cement in Early Childhood Caries
2013
Background. Early childhood caries is a widely prevalent disease throughout the world. It is necessary to treat this condition in early childhood; however, child behavior management may be particularly challenging during treatment. To overcome this challenge, we used Carigel to remove caries and RelyX Unicem resin cement for strip crown restoration. It not only has the desired aesthetic effect but is also more effective for primary teeth, which are used for a shorter period than permanent teeth are. Case Presentation. We report a case of three pediatric patients with early childhood caries, in whom caries was removed by using Carigel to avoid the risk of pulpal exposure associated with high-speed handpieces. Subsequently, aesthetic restoration was performed using strip crown with RelyX Unicem self-adhesive resin cement. Conclusion. RelyX Unicem has the following advantages: (1) not requiring have any special skills for the dentist for performing the procedure, (2) decreased occurrence of bubbles during injection of the cement, and (3) overall short duration of the procedure. Thus, it is appropriate for the treatment of pediatric patients whose behavior is difficult to manage. However, further studies are required in order to establish the use of RelyX Unicem as a stable restorative material in early childhood caries.
Journal Article
OrthoMTAtm A Newly Developed Mineral Trioxide Aggregate (MTA) Cements in Outpatients Attending Public Oral Health Korean Adolescents
2016
OrthoMTAtm A Newly Developed Mineral Trioxide Aggregate (MTA) Cements in Outpatients Attending Public Oral Health Korean Adolescents
Journal Article