Publications by authors named "Misun Kang"

28 Publications

  • Page 1 of 1

Mineralized Peyronie's plaque has a phenotypic resemblance to bone.

Acta Biomater 2021 Nov 21. Epub 2021 Nov 21.

Division of Biomaterials and Bioengineering, Department of Preventative and Restorative Dental Sciences, School of Dentistry, University of California San Francisco, California, United States of America; Department of Urology, School of Medicine, University of California, San Francisco, California, United States of America. Electronic address:

Mineralized Peyronie's plaque (MPP) impairs penile function. The association, colocalization, and dynamic interplay between organic and inorganic constituents can provide insights into biomineralization of Peyronie's plaque. Human MPPs (n = 11) were surgically excised, and the organic and inorganic constituents were spatially mapped using multiple high-resolution imaging techniques. Multiscale image analyses resulted in spatial colocalization of elements within a highly porous material with heterogenous composition, lamellae, and osteocytic lacuna-like features with a morphological resemblance to bone. The lower (520 ±179 mg/cc) and higher (1024 ± 155 mg/cc) mineral density regions were associated with higher (11%) and lower (7%) porosities in MPP. Energy dispersive X-ray and micro-X-ray fluorescent spectroscopic maps in the higher mineral density regions of MPP revealed higher counts of calcium (Ca) and phosphorus (P), and a Ca/P ratio of 1.48 ± 0.06 similar to bone. More importantly, higher counts of zinc (Zn) were localized at the interface between softer (more organic to inorganic ratio) and harder (less organic to inorganic ratio) tissue regions of MPP and adjacent softer matrix, indicating the involvement of Zn-related proteins and/or pathways in the formation of MPP. In particular, dentin matrix protein-1 (DMP-1) was colocalized in a matrix rich in proteoglycans and collagen that contained osteocytic lacuna-like features. This combined materials science and biochemical with correlative microspectroscopic approach provided insights into the plausible cellular and biochemical pathways that incite mineralization of an existing fibrous Peyronie's plaque. STATEMENT OF SIGNIFICANCE: Aberrant human penile mineralization is known as mineralized Peyronie's plaque (MPP) and often results in a loss of form and function. This study focuses on investigating the spatial association of matrix proteins and elemental composition of MPP by colocalizing calcium, phosphorus, and trace metal zinc with dentin matrix protein 1 (DMP-1), acidic proteoglycans, and fibrillar collagen along with the cellular components using high resolution correlative microspectroscopic techniques. Spatial maps provided insights into cellular and biochemical pathways that incite mineralization of fibrous Peyronie's plaque in humans.
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http://dx.doi.org/10.1016/j.actbio.2021.11.025DOI Listing
November 2021

Cold-pressed oil from inhibits the proliferation of vascular smooth muscle cells via regulation of PI3K/MAPK signaling pathways.

Exp Ther Med 2022 Jan 2;23(1):21. Epub 2021 Nov 2.

Institute for Bio-Medical Convergence, College of Medicine, Catholic Kwandong University, Gangneung, Gangwon 25601, Republic of Korea.

Vascular occlusive disease is a chronic disease with significant morbidity and mortality. Although a variety of therapies and medications have been developed, the likelihood of disease re-emergence is high and this can be life-threatening. Based on a previous screening experiment related to vascular obstructive diseases using 34 types of essential oils, cold-pressed oil (CpO) from (lime) has been demonstrated to have the best effect for the inhibition of vascular smooth muscle cells (VSMCs) proliferation. The aim of the present study was to evaluate the effect of lime CpO on the pathological changes of VSMCs. To determine this, the effect of lime CpO on VSMC proliferation, a major cause of vascular disease, was investigated. To determine the safe concentration interval for toxicity of CpO during VSMC culture, a dilution of 1x10 was determined using Cell Counting Kit-8 assay, which was confirmed to be non-toxic using a lactate dehydrogenase assay. To examine the effect of lime CpO in cellular signaling pathways, changes in phosphorylation of both the PI3K/AKT/mTOR and extracellular signal-regulated MEK/ERK signaling pathways with serum were investigated. Furthermore, lime CpO with FBS also significantly decreased the expression levels of the cell cycle regulators cyclin D1 and proliferating cell nuclear antigen. Additionally, lime CpO with FBS significantly inhibited the sprouting of VSMCs in an culture system. These results suggested that lime CpO inhibited the abnormal proliferation of VSMCs and can be developed as a nature-based therapeutic agent for obstructive vascular disease.
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http://dx.doi.org/10.3892/etm.2021.10943DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8593924PMC
January 2022

Outdoor thermal stress changes in South Korea: Increasing inter-annual variability induced by different trends of heat and cold stresses.

Sci Total Environ 2022 Jan 4;805:150132. Epub 2021 Sep 4.

High Impact Weather Research Department, National Institute of Meteorological Sciences, South Korea. Electronic address:

Changes of thermal environment can lead to unfavorable impacts such as a decrease of thermal stratification, increase of energy consumption, and increase of thermal health risk. Investigating changes in outdoor thermal environments can provide meaningful information for addressing economic and social issues and related challenges. In this study, thermal environment changes in South Korea were investigated using a nonstationary two-component Gaussian mixture model (NSGMM) for air temperature and two thermal comfort indices. For this, the perceived temperature (PT) and universal thermal climate index (UTCI) were employed as the thermal comfort index. Thermal comfort indices were computed using observed meteorological data at 26 weather stations for 37 years in South Korea. Meanwhile, trends of thermal comforts in the warm and cool seasons were simultaneously modeled by the NSGMM. The results indicate significant increasing trends in thermal comfort indices for South Korea. The increasing trends in thermal comfort indices both the warm and cool seasons were detected while the magnitudes of the trends are significantly different. This difference between the magnitude of trends led to an increase in mean and inter-annual variability of thermal comfort indices based on PT, while an increase of mean and decrease of inter-annual variability were observed based on the UTCI. Moreover, the annual proportion of the category referring to days in comfort based on the results of PT has decreased due to the different trends of thermal comfort indices in the warm and cool seasons. This decrease may lead to an increase of thermal health risk that is larger than what would be expected from the results considering the increasing trend of the annual mean temperature in South Korea. From this result, it can be inferred that the thermal health risk in South Korea may be more adverse than what we originally expected from the current temperature trend.
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http://dx.doi.org/10.1016/j.scitotenv.2021.150132DOI Listing
January 2022

Corrigendum to "Physicochemical and biochemical spatiotemporal maps of a mouse penis". [J. Biomech. 101 (2020) 109637].

J Biomech 2021 Aug 25;125:110563. Epub 2021 Jun 25.

Division of Biomaterials and Bioengineering, Department of Preventive and Restorative Dental Sciences, School of Dentistry, University of California San Francisco, San Francisco, CA, United States; Department of Urology, School of Medicine, University of California San Francisco, San Francisco, CA, United States. Electronic address:

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http://dx.doi.org/10.1016/j.jbiomech.2021.110563DOI Listing
August 2021

Structure and elemental composition of Ceftriaxone induced pediatric nephrolithiasis.

Urolithiasis 2021 Aug 15;49(4):309-320. Epub 2021 Feb 15.

Department of Urology, Beijing Friendship Hospital, Capital Medical University, 95 Yong An Road, Xi Cheng District, Beijing, 100050, China.

Ceftriaxone is a widely used antibiotic because to its broad-spectrum gram-negative coverage, safety, and biological half life (5-9 h) permit dose once-daily administration. It is specifically used in pediatric patients in developing countries. Ceftriaxone forms insoluble sludge/stone when combined with calcium in the urinary system. In this study, Ceftriaxone induced sludge/stones from pediatric patients were collected to identify its microstructure and composition to gather insights into the mechanism of Ceftriaxone induced sludge/stone formation. The results illustrated that Ceftriaxone induced stones formed rapidly following antibiotic administration. Ceftriaxone calcium salt crystals could easily be broken with minimal intervention. However, Ceftriaxone combined with calcium phosphate formed an insoluble stone aggregate.
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http://dx.doi.org/10.1007/s00240-020-01231-5DOI Listing
August 2021

Structural and chemical heterogeneities of primary hyperoxaluria kidney stones from pediatric patients.

J Pediatr Urol 2021 04 20;17(2):214.e1-214.e11. Epub 2020 Nov 20.

Division of Preclinical Education, Biomaterials & Engineering, School of Dentistry, University of California San Francisco, San Francisco, CA, 94143, USA; Department of Urology, School of Medicine, University of California San Francisco, San Francisco, CA, 94143, USA. Electronic address:

Objective: Calcium oxalate stones are the most common type among stone-forming patients and in some cases result from predisposed genetic conditions. In this work, we examined the differences in structure and chemical composition between oxalate stones from patients from three groups: 1) pediatric patients that were genetically predisposed (primary hyperoxaluria) to form stones (PPH); 2) control pediatric patients that did not have such genetic predisposition (PN-PH); 3) adult patients that formed oxalate stones without the genetic predisposition (A-CaOx). A variety of instrumental analyses were conducted to identify physicochemical properties of stones characteristic of predisposed pediatric (PPH), pediatric hyperoxaluria (PN-PH), and adult (A-CaOx) patient populations.

Methods: Genetic variants of 16 stone-forming patients were determined using whole-exome gene sequencing. Components of stones from PPH (n = 6), PN-PH (n = 5), and A-CaOx (n = 5) groups were identified using Fourier transform infrared (FTIR) spectroscopy. Stone morphology and density were evaluated using high resolution X-ray computed tomography (micro-XCT). Stone microstructure and elemental composition were mapped with scanning electron microscopy (SEM) and energy dispersive X-ray (EDX) spectroscopy, respectively.

Results: Calcium oxalate bipyramidal crystals were found on stones from all groups. Stones from PPH patients with PH types I and II were composed of calcium oxalate monohydrate (COM) with relatively uniform mineral density (1224 ± 277 mg/cc) and distinct smooth surfaces. By contrast, micro-spherical calcium phosphate particles were found only on PN-PH stones, which also showed a broader range of mineral densities (1266 ± 342 mg/cc). Stones from the PN-PH group also contained phosphorus (P), which was absent in NP-PH stones. A-CaOx stones were of significantly lower mineral density (645 ± 237 mg/cc) than pediatric stones and were more heterogeneous in their elemental composition.

Conclusion: Unique structural and compositional characteristics were identified in stones from pediatric patients with primary hyperoxaluria. These include the absence of phosphorus, a narrower mineral density distribution, and a uniform elemental composition compared to stones from pediatric patients without the genetic predisposition. Thus, characterization of stones at the macro- and micro-scales in combination with genetic testing of patients can provide insights and accurate diagnosis to develop a treatment plan for effective patient care.
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http://dx.doi.org/10.1016/j.jpurol.2020.11.023DOI Listing
April 2021

Event-Based Heat-Related Risk Assessment Model for South Korea Using Maximum Perceived Temperature, Wet-Bulb Globe Temperature, and Air Temperature Data.

Int J Environ Res Public Health 2020 04 11;17(8). Epub 2020 Apr 11.

Applied Meteorology Research Division, National Institute of Meteorological Sciences, Seohobuk-ro 33, Seogwipo 63568, Korea.

This study aimed to assess the heat-related risk (excess mortality rate) at six cities, namely, Seoul, Incheon, Daejeon, Gwangju, Daegu, and Busan, in South Korea using the daily maximum perceived temperature (PTmax), which is a physiology-based thermal comfort index, the wet-bulb globe temperature, which is meteorology-based thermal comfort index, and air temperature. Particularly, the applicability of PTmax was evaluated using excess mortality rate modeling. An event-based heat-related risk assessment model was employed for modeling the excess mortality rate. The performances of excess mortality rate models using those variables were evaluated for two data sets that were used (training data, 2000-2016) and not used (test data, 2017-2018) for the construction of the assessment models. Additionally, the excess mortality rate was separately modeled depending on regions and ages. PTmax is a good temperature indicator that can be used to model the excess mortality rate in South Korea. The application of PTmax in modeling the total mortality rate yields the best performances for the test data set, particularly for young people. From a forecasting perspective, PTmax is the most appropriate temperature indicator for assessing the heat-related excess mortality rate in South Korea.
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http://dx.doi.org/10.3390/ijerph17082631DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7215463PMC
April 2020

A Combinational Therapy of Articular Cartilage Defects: Rapid and Effective Regeneration by Using Low-Intensity Focused Ultrasound After Adipose Tissue-Derived Stem Cell Transplantation.

Tissue Eng Regen Med 2020 06 9;17(3):313-322. Epub 2020 Apr 9.

International St. Mary's Hospital, Catholic Kwandong University, 25, Simgok-ro 100beon-gil, Seo-gu, Incheon, 22711, Republic of Korea.

Background: Although low-intensity pulsed ultrasound has been reported to be potential cartilage regeneration, there still unresolved treatment due to cartilage fibrosis and degeneration by a lack of rapid and high-efficiency treatment. The purpose of this study was to investigate the effect of a combination therapy of focused acoustic force and stem cells at site for fast and efficient healing on cartilage regeneration.

Methods: Using a rat articular cartilage defects model, one million adipose tissue-derived stem cells (ASCs) were injected into the defect site, and low-intensity focused ultrasound (LOFUS) in the range of 100-600 mV was used for 20 min/day for 2 weeks. All experimental groups were sacrificed after 4 weeks in total. The gross appearance score and hematoxylin and eosin (H&E), Alcian blue, and Safranin O staining were used for measuring the chondrogenic potential. The cartilage characteristics were observed, and type II collagen, Sox 9, aggrecan, and type X collagen were stained with immunofluorescence. The results of the comprehensive analysis were calculated using the Mankin scoring method.

Results: The gross appearance scores of regenerated cartilage and chondrocyte-like cells in H&E images were higher in LOFUS-treated groups compared to those in negative control or ASC-treated groups. Safranin O and Alcian blue staining demonstrated that the 100 and 300 mV LOFUS groups showed greater synthesis of glycosaminoglycan and proteoglycan. The ASC + LOFUS 300 mV group showed positive regulation of type II collagen, Sox 9 and aggrecan and negative regulation of type X collagen, which indicated the occurrence of cartilage regeneration based on the Mankin score result.

Conclusion: The combination therapy, which involved treatment with ASC and 300 mV LOFUS, quickly and effectively reduced articular cartilage defects.
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http://dx.doi.org/10.1007/s13770-020-00256-6DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7260301PMC
June 2020

Fatty acid-binding protein 4 downregulation drives calcification in the development of kidney stone disease.

Kidney Int 2020 05 29;97(5):1042-1056. Epub 2020 Feb 29.

Department of Urology, University of California, San Francisco, California, USA. Electronic address:

Nephrolithiasis is a significant source of morbidity, and its incidence has increased significantly over the last decades. This rise has been attributed to concurrent increasing rates of obesity, associated with a 3-time risk of developing NL. To date, the mechanism by which obesity is linked to stone formation has not been elucidated. We aimed to utilize a transcriptomics approach to discover the missing link between these two epidemic diseases. We investigated gene expression profiling of nephrolithiasis patients by two RNA-sequencing approaches: comparison between renal papilla tissue with and without the presence of calcified Randall's plaques (RP), and comparison between the papilla, medulla, and cortex regions from within a single recurrent stone forming kidney. Results were overlaid between differently expressed genes found in the patient cohort and in the severely lithogenic kidney to identify common genes. Overlay of these two RNA-sequencing datasets demonstrated there is impairment of lipid metabolism in renal papilla tissue containing RP linked to downregulation of fatty acid binding protein (FABP) 4. Immunohistochemistry of human kidney specimens and microarray analysis of renal tissue from a nephrolithiasis mouse model confirmed that FABP4 downregulation is associated with renal stone formation. In a FABP4 knockout mouse model, FABP4 deficiency resulted in development of both renal and urinary crystals. Our study revealed that FABP4 plays an important, previously unrecognized role in kidney stone formation, providing a feasible mechanism to explain the link between nephrolithiasis and metabolic syndrome.
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http://dx.doi.org/10.1016/j.kint.2020.01.042DOI Listing
May 2020

Polymicrobial periodontal disease triggers a wide radius of effect and unique virome.

NPJ Biofilms Microbiomes 2020 03 10;6(1):10. Epub 2020 Mar 10.

Department of Orofacial Sciences, School of Dentistry, University of California San Francisco, San Francisco, CA, USA.

Periodontal disease is a microbially-mediated inflammatory disease of tooth-supporting tissues that leads to bone and tissue loss around teeth. Although bacterially-mediated mechanisms of alveolar bone destruction have been widely studied, the effects of a polymicrobial infection on the periodontal ligament and microbiome/virome have not been well explored. Therefore, the current investigation introduced a new mouse model of periodontal disease to examine the effects of a polymicrobial infection on periodontal ligament (PDL) properties, changes in bone loss, the host immune response, and the microbiome/virome using shotgun sequencing. Periodontal pathogens, namely Porphyromonas gingivalis, Treponema denticola, Tannerella forsythia, and Fusobacterium nucleatum were used as the polymicrobial oral inoculum in BALB/cByJ mice. The polymicrobial infection triggered significant alveolar bone loss, a heightened antibody response, an elevated cytokine immune response, a significant shift in viral diversity and virome composition, and a widening of the PDL space; the latter two findings have not been previously reported in periodontal disease models. Changes in the PDL space were present at sites far away from the site of insult, indicating that the polymicrobial radius of effect extends beyond the bone loss areas and site of initial infection and wider than previously appreciated. Associations were found between bone loss, specific viral and bacterial species, immune genes, and PDL space changes. These findings may have significant implications for the pathogenesis of periodontal disease and biomechanical properties of the periodontium. This new polymicrobial mouse model of periodontal disease in a common mouse strain is useful for evaluating the features of periodontal disease.
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http://dx.doi.org/10.1038/s41522-020-0120-7DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7064479PMC
March 2020

Physicochemical and biochemical spatiotemporal maps of a mouse penis.

J Biomech 2020 03 16;101:109637. Epub 2020 Jan 16.

Division of Biomaterials and Bioengineering, Department of Preventive and Restorative Dental Sciences, School of Dentistry, University of California San Francisco, San Francisco, CA, United States; Department of Urology, School of Medicine, University of California San Francisco, San Francisco, CA, United States. Electronic address:

Spatiotemporal mechanobiology resulting in penile pathologies continues to be investigated using small scale animals models such as mice. However, species-dependent functional biomechanics of a mouse penis, is not known. In this study, spatial mapping of a mechanosensitive transcription factor, scleraxis (Scx), at ages 4, 5, 6 weeks, and 1 year were generated to identify mechanoactive regions within penile tissues. Reconstructed volumes of baculum collected using micro X-ray computed tomography illustrated significantly increased baculum length with decreased porosity, and increased mineral density (p < 0.05) with age. The bony-baculum was held centrally in the Scx positive corpus cavernosum glandis (CCG), indicating mechanoactivity within the struts in a 6 week old mouse. The struts also were stained positive for fibrillar proteins including collagen and elastin, and globular proteins including protein gene product 9.5, and α-smooth muscle actin. The corpus cavernosum penis (CCP) contained significantly (p < 0.05) more collagen than CCG within the same penis, and both regions contained blood vessels with equivalent innervation at any given age. Comparison of volumes of flaccid and erect penile forms revealed functional characteristics of the CCP. Results of this study provided insights into biomechanical function of the CCG; in that, it is a high-pressure chamber that stiffens the penis and is similar to the human corpus cavernosum.
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http://dx.doi.org/10.1016/j.jbiomech.2020.109637DOI Listing
March 2020

Biomechanical pathways of dentoalveolar fibrous joints in health and disease.

Periodontol 2000 2020 02;82(1):238-256

Division of Preclinical Education, Biomaterials & Engineering, Department of Preventive and Restorative Dental Sciences, School of Dentistry, University of California San Francisco, San Francisco, California, USA.

Spatial and temporal adaptations within periodontal tissues and their interfaces result from functional loads. Functional loads can be physiologic and/or pathologic in nature. The prolonged effect of these loads can alter the overall biomechanics of a dentoalveolar fibrous joint (dentoalveolar joint) by changing the form of the tooth root and its socket. This "sculpting" of the tooth root and alveolar bony socket is a consequence of several mechano-biological changes that occur within the periodontal complex of a load-bearing dentoalveolar joint. These include changes in biochemical expressions, structure, elemental composition, and mechanical properties of alveolar bone, the underlying tissues of the roots of teeth, and their interfaces. These physicochemical changes in tissues continue to prompt mechano-responsive biochemical activities at the attachment sites of periodontal ligament (soft) with bone (hard), and ligament with cementum (hard), which are the entheses of a load-bearing dentoalveolar joint. Forces at soft-hard tissue attachment sites between disparate materials with different stiffness values theoretically generate strain singularities or discontinuities. These discontinuities under prolonged functional loading increase the probability for failure to occur specifically at the enthesial zones. However, in a normal dentoalveolar joint, gradual stiffness gradients exist from ligament to bone, and from ligament to cementum. The gradual transitions in stiffness from softer ligament (lower stiffness) to harder bone or cementum (higher stiffness) or vice versa optimize tissue and interfacial strains. Optimization of tissue and ligament-enthesial physical and chemical properties facilitates transmission of cyclic forces of varying magnitudes and frequencies that collectively maintain the overall biomechanics of a dentoalveolar joint. The objectives of this review are 3-fold: (i) to illustrate physicochemical adaptations at the periodontal ligament entheses of a human periodontal complex affected by subgingival calculus; (ii) to demonstrate how to "program" the hallmarks of periodontitis in small-scale vertebrates in vivo to generate spatiotemporal maps of physicochemical adaptations in a diseased dentoalveolar joint; and (iii) to correlate dentoalveolar joint biomechanics in healthy and diseased states to spatiotemporal maps of physicochemical adaptations within respective periodontal tissues. This interdisciplinary approach demonstrates that physicochemical adaptations within periodontal tissues using the mechanics of materials (tissue mechanics), materials science (tissue composition), and mechano-biology (matrix molecules) can help explain the mechano-adaptation of dentoalveolar joints in normal and diseased functional states. Multiscale biomechanics and mechano-biology approaches can provide insights into the functional competence of a diseased relative to a normal dentoalveolar joint. Insights gathered from interdisciplinary and multiscale biomechanics approaches include the following: (i) physiologic loads related to chewing maintain a balance between mineral-forming and-resorbing biochemical cellular events, resulting in gradual stiffness gradients at the periodontal ligament entheses, and, in turn, sustain the overall biomechanics of a normal "healthy" dentoalveolar joint; (ii) pathologic loads resulting from tissue degradation and physical changes to the periodontal complex promote an abrupt stiffness gradient at the periodontal ligament entheses. The shift from gradual to an abrupt stiffness gradient could prompt a shift in the biochemical cascades, exacerbate mechano-responsive biochemical expressions at periodontal ligament entheses farther away from the site of insult, and culminate in joint degradation; (iii) sustained pathologic function on periodontally diseased joints exacerbates degradation of periodontal ligament entheses providing insights into "rescue therapy", such as the use of an adequate "mechanocal dose" to regain joint function; and (iv) spatiotemporal maps of changes in biochemical expressions, and physicochemical properties of strain-dominated affected sites, including the periodontal ligament entheses, can guide anatomy-specific therapeutics for tissue regeneration and/or disease control with the purpose of regaining dentoalveolar joint function. Modulation of occlusal loads could minimize disease progression and potentially assist in regaining functional attachment of ligament to bone and/or ligament to cementum of the dentoalveolar joint. Elucidating mechanisms that drive the breakdown of the functionally active periodontal complex burdened with microbes will provide the required critical insights into regenerative medicine and/or biomimetic approaches that would facilitate rescue/regain of dentoalveolar joint function.
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http://dx.doi.org/10.1111/prd.12306DOI Listing
February 2020

The Fracture Callus Is Formed by Progenitors of Different Skeletal Origins in a Site-Specific Manner.

JBMR Plus 2019 Sep 4;3(9):e10193. Epub 2019 May 4.

Endocrine Unit, University of California San Francisco and Veterans Affairs Medical Center San Francisco CA USA.

We evaluated repair following a mid-diaphyseal fracture of the tibia in 3-month-old mice. We observed differences in the repair process at three different sites of the callus. Site 1: bone developing from the outer layer of the periosteum of the cortex; site 2: bone developing within the bridge/central region of the fracture; and site 3: bone developing within the marrow of the ends of broken bones. We characterized these sites by correlating datasets from X-ray CT and histology. Correlated data demonstrated the involvement of different cells and different rates of mineralization. The origin of the progenitors and mechanism of progenitor differentiation involved at these sites was then evaluated using lineage tracing of cells expressing Prx1 and Col.2. The Prx1 progeny contributed to intramembranous bone formation (IBF) at site 1 and endochondral bone formation (EndoBF) at site 2 but not to intramedullary bone formation (IMBF) at site 3. IBF at site 1 was confirmed without a chondrocyte intermediate unlike EndoBF at site 2. Additionally, the presence of Col.2 progeny contributed to EndoBF in site 2 and IMBF in site 3 but not to IBF in site 1. However, the Col.2 progeny in IMBF in site 3 appeared to come from Col.2-expressing osteocytes originating in the cortices of the ends of the fractured bone. In conclusion we have identified three sites of bone fracture repair that differ in their origin of cells and their mechanisms of bone formation. © 2019 The Authors JBMR Plus published by Wiley Periodicals, Inc. on behalf of American Society for Bone and Mineral Research.
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http://dx.doi.org/10.1002/jbm4.10193DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6808225PMC
September 2019

Facile synthesis of sub-10 nm-sized bright red-emitting upconversion nanophosphors via tetrahedral YOF:Yb,Er seed-mediated growth.

Chem Commun (Camb) 2019 Nov 10;55(89):13350-13353. Epub 2019 Oct 10.

Materials Architecturing Research Center, Korea Institute of Science and Technology, 5, Hwarang-ro 14-gil, Seongbuk-gu, Seoul 02792, Republic of Korea. and Division of Nano & Information Technology, KIST School, Korea University of Science and Technology (UST), Seoul 02792, Republic of Korea.

Ultrasmall and uniform tetrahedral-shaped YOF:Yb,Er upconversion nanophosphors (UCNs) are synthesized and sub-10 nm YOF:Yb,Er/YOF core/shell UCNs are formed via YOF:Yb,Er seed-mediated synthesis. The ultrasmall YOF:Yb,Er/YOF core/shell UCNs realize intense red emission under near infrared light (λ = 980 nm).
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http://dx.doi.org/10.1039/c9cc06797cDOI Listing
November 2019

Growth and Chloroplast Replacement of the Benthic Mixotrophic Ciliate Mesodinium coatsi.

J Eukaryot Microbiol 2019 07 11;66(4):625-636. Epub 2019 Jan 11.

LOHABE, Department of Oceanography, Chonnam National University, Gwangju, 61186, Korea.

While the ecophysiology of planktonic Mesodinium rubrum species complex has been relatively well studied, very little is known about that of benthic Mesodinium species. In this study, we examined the growth response of the benthic ciliate Mesodinium coatsi to different cryptophyte prey using an established culture of this species. M. coatsi was able to ingest all of the offered cryptophyte prey types, but not all cryptophytes supported its positive, sustained growth. While M. coatsi achieved sustained growth on all of the phycocyanin-containing Chroomonas spp. it was offered, it showed different growth responses to the phycoerythrin-containing cryptophytes Rhodomonas spp., Storeatula sp., and Teleaulax amphioxeia. M. coatsi was able to easily replace previously ingested prey chloroplasts with newly ingested ones within 4 d, irrespective of prey type, if cryptophyte prey were available. Once retained, the ingested prey chloroplasts seemed to be photosynthetically active. When fed, M. coatsi was capable of heterotrophic growth in darkness, but its growth was enhanced significantly in the light (14:10 h light:dark cycle), suggesting that photosynthesis by ingested prey chloroplast leads to a significant increase in the growth of M. coatsi. Our results expand the knowledge of autecology and ecophysiology of the benthic M. coatsi.
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http://dx.doi.org/10.1111/jeu.12709DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6766864PMC
July 2019

Microanatomical changes and biomolecular expression at the PDL-entheses during experimental tooth movement.

J Periodontal Res 2019 Jun 28;54(3):251-258. Epub 2018 Nov 28.

Division of Biomaterials and Bioengineering, Department of Preventive and Restorative Dental Sciences, University of California, San Francisco, California.

The novel aspect of this study was to contextualize the co-localization of biomolecular expression in widened and narrowed periodontal ligament (PDL)-space within a mechanically activated periodontal complex. The PDL is unique as it is the only ligament with both innervation and vascularization. Maxillary molars in 6-week-old male C57BL/6 mice (N = 5) were experimentally translated for 2 weeks using an elastic spacer. Contralateral teeth were used as controls. Mechanical testing of the periodontal complex of a mouse in situ and imaging using X-ray micro-computed tomography (micro-XCT) illustrated deformations within blood vessels (BV) of the PDL. PDL-bone and PDL-cementum entheses at the widened and narrowed PDL-spaces following experimental tooth movement (ETM) illustrated osterix (OSX), bone sialoprotein (BSP), cluster of differentiation 146 (CD146), and protein gene product 9.5 (PGP9.5), indicating active remodeling at these sites. PGP9.5 positive nerve bundles (NBs) were co-localized with multinucleated cells (MCs), Howship's resorption lacunae, and CD146 positive BVs. Association between nerves and MC was complemented by visualizing the proximity of osmium tetroxide stained NBs with the ultrastructure of MCs by performing scanning transmission electron microscopy. Spatial association of NB with BV, and NB with MC, provided insights into the plausible co-activation of NBs to initiate osteoclastic activity. Resorption of mineral occurred as an attempt to restore PDL-space of the load-bearing complex, specifically at the PDL-entheses. Mapping of anatomy-specific structural elements and their association with regenerative molecules by correlating light and electron micrographs provided insights into the use of these extracellular matrix molecules as plausible targets for pharmacological interventions related to tooth movement. Within the realm of tissue regeneration, modulation of load can reverse naturally occurring mineral formation to experimentally induced resorption, and naturally occurring mineral resorption to experimentally induced formation at the enthesial sites to permit tooth translation.
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http://dx.doi.org/10.1111/jre.12625DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6465084PMC
June 2019

Quantification and evaluation of intra-urban heat-stress variability in Seoul, Korea.

Int J Biometeorol 2019 Jan 20;63(1):1-12. Epub 2018 Nov 20.

Institute of Ecology, Technische Universität Berlin, Rothenburgstraße 12, 12165, Berlin, Germany.

This study quantifies heat-stress hazard (air temperature), vulnerability (heat vulnerability index and age score), and risk (heat-related mortality) on the district scale in Seoul, Korea, for a comprehensive heat-stress impact assessment. Moreover, the heat-stress impact assessment is evaluated by checking the spatial consistency between heat-stress hazard, vulnerability, and risk, which was rarely done before. We applied numerical and geo-empirical models to simulate the spatial pattern of heat-stress hazard. For heat-stress vulnerability, we used demographic and socioeconomic factors. Heat-related mortality was estimated based on an event-based heat-stress risk analysis. Results are that heat-stress hazard, vulnerability, and risk are spatially variable in Seoul. The highest heat-stress hazard was detected in the districts Mapo, Yeongdeungpo, and Yangcheon, the highest vulnerability in Jongno and the highest risk in Jongno and Yangcheon. The different components (heat-stress hazard, vulnerability, and risk) and variables (heat vulnerability index and percentage of seniors) showed different spatial patterns. Knowledge about the causes of higher heat-stress risk, either the hazard or vulnerability, is helpful to design tailored adaptation measures that focus on the reduction of thermal loads or on the preparation of the vulnerable population. The evaluation showed that heat-stress vulnerability and hazard explain the spatial pattern of risk only partly. This highlights the need to evaluate heat-stress impact assessment systems to produce reliable urban heat-stress maps.
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http://dx.doi.org/10.1007/s00484-018-1631-2DOI Listing
January 2019

Architecture-Guided Fluid Flow Directs Renal Biomineralization.

Sci Rep 2018 09 21;8(1):14157. Epub 2018 Sep 21.

Department of Urology, School of Medicine, University of California San Francisco, San Francisco, CA, 94143, USA.

Nephrocalcinosis often begins on a calcium phosphate deposit, at the tip of the medullo-papillary complex (MPC) known as Randall's plaque (RP). Contextualizing proximally observed biominerals within the MPC has led us to postulate a mechanobiological switch that can trigger interstitial biomineralization at the MPC tip, remote from the intratubular biominerals. Micro X-ray computed tomography scans of human MPCs correlated with transmission and scanning electron micrographs, and X-ray energy dispersive spectrometry demonstrated novel findings about anatomically-specific biominerals. An abundance of proximal intratubular biominerals were associated with emergence of distal interstitial RP. The fundamental architecture of the MPC and mineral densities at the proximal and distal locations of the MPC differed markedly. A predominance of plate-like minerals or radially oriented plate-like crystallites within spheroidal minerals in the proximal intratubular locations, and core-shell type crystallites within spheroidal minerals in distal interstitial locations were observed. Based on the MPC anatomic location of structure-specific biominerals, a biological switch within the mineral-free zone occurring between the proximal and distal locations is postulated. The "on" and "off" switch is dependent on changes in the pressure differential resulting from changes in tubule diameters; the "Venturi effect" changes the "circumferential strain" and culminates in interstitial crystal deposits in the distal tubule wall in response to proximal tubular obstruction. These distal interstitial mineralizations can emerge into the collecting system of the kidney linking nephrocalcinosis with nephrolithiasis.
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http://dx.doi.org/10.1038/s41598-018-30717-xDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6155006PMC
September 2018

Novel insights into renal mineralization and stone formation through advanced imaging modalities.

Connect Tissue Res 2018 12;59(sup1):102-110

a Department of Urology , University of California San Francisco , San Francisco , California , USA.

Purpose/Aim: The most common kidney stone composed of calcium oxalate forms on interstitial calcium phosphate mineral known as a Randall's plaque (RP). Due to limited information about events leading to the initial deposition of nanometer size interstitial calcium phosphate pre-clusters, there continues to be a debate on the initial site of calcium phosphate deposition and factors leading to stone formation.

Materials And Methods: High-resolution X-ray micro-computed tomography (CT), and light and electron microscopy techniques were used to characterize human renal pyramids and five representative kidney stones with identifiable stems. Mineral densities of mineralized aggregates within these specimens were correlated with micro- and ultra-structures as seen using light and electron microscopy techniques.

Results: The earliest detectable biominerals in the human renal papilla were proximal intratubular plate-like calcium phosphate deposits. Unoccluded tubules in stems connected to calcium phosphate stones were observed by electron microscope and X-ray micro-CT. These tubules were similar in diameter (30-100 μm) and shape to those observed in the distal regions of the renal papilla.

Conclusions: Observations were patterned through a novel and unified theory of stepwise-architecture guided biomineralization (a combination of smaller structures leading to a larger but similar structural framework). A plausible stepwise progression in renal biomineralization is proposed; proximal intratubular calcium phosphate deposits can lead to interstitial yet calcium phosphate rich RP and mature into a stem on which a calcium oxalate stone grows within the collecting system of a kidney.
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http://dx.doi.org/10.1080/03008207.2017.1409219DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6120852PMC
December 2018

A continuum of mineralization from human renal pyramid to stones on stems.

Acta Biomater 2018 04 9;71:72-85. Epub 2018 Feb 9.

Department of Urology, University of California San Francisco, San Francisco, CA 94143, United States; Division of Biomaterials and Bioengineering, Department of Preventive and Restorative Dental Sciences, University of California San Francisco, San Francisco, CA 94143, United States. Electronic address:

The development of new modalities for kidney stone prevention rests upon understanding the progression of mineralization within the renal pyramid. The progression from small foci of mineralized volumes within the renal pyramid to larger interstitial plaques that ultimately lead into clinically detectable calcium-based stones on calcium phosphate stems will be presented through correlative microscopy approach. High resolution X-ray computed tomography (micro-XCT), electron microscopy, and energy dispersive X-ray (EDX) compositional analyses of interstitial plaques, stems, and attached stones were performed. Increase in mineral density progressed with mineralization severity, with the highest mineral densities detected within mature Randall's plaque and stems to which kidney stones were attached. EDX analyses revealed variable elemental composition within interstitial plaque, stems, and stones. Micro-XCT reconstructions of stones with stems enabled visualization of unoccluded tubules within stems, with average tubule diameters corresponding to thin limbs of Henle, blood vessels, and collecting ducts. Correlative microscopy confirmed that the progression of mineralization leading to calcium-based nephrolithiasis occurs through a continuum involving four anatomically and structurally distinct biomineralization regions: 1) proximal intratubular mineralization within the renal pyramid; 2) interstitial Randall's plaque near the tip of the papilla; 3) emerging plaque (stems); and, 4) the body of heterogeneous stones.

Statement Of Significance: Nephrolithiasis is a common condition affecting nearly 1 in 11 Americans. The most common type of stone, calcium oxalate is known to form on a calcium phosphate deposit on the renal papilla known as Randall's plaque. Novel imaging techniques have identified distinct regions of biomineralization not just at the tip, but throughout the renal papilla. The classic understanding of Randall's plaque formation is reformulated using correlative imaging techniques. This study establishes a stepwise progression of anatomically-specific biomineralization events including, 1) proximal intratubular mineralization within the renal pyramid; 2) interstitial Randall's plaque near the tip of the papilla; 3) emerging plaque (stems); and, 4) the body of heterogeneous stones, and provides insights into the need for plausible site-specific therapeutic intervention.
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http://dx.doi.org/10.1016/j.actbio.2018.01.040DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5899955PMC
April 2018

Ring finger protein 126 (RNF126) suppresses ionizing radiation-induced p53-binding protein 1 (53BP1) focus formation.

J Biol Chem 2018 01 22;293(2):588-598. Epub 2017 Nov 22.

From the Department of Biological Sciences, Sungkyunkwan University, Suwon 16419, Republic of Korea,

Cells have evolved sophisticated mechanisms to maintain genomic integrity in response to DNA damage. Ionizing radiation (IR)-induced DNA damage results in the formation of IR-induced foci (iRIF) in the nucleus. The iRIF formation is part of the DNA damage response (DDR), which is an essential signaling cascade that must be strictly regulated because either the loss of or an augmented DDR leads to loss of genome integrity. Accordingly, negative regulation of the DDR is as critical as its activation. In this study, we have identified ring finger protein 126 (RNF126) as a negative regulator of the DDR from a screen of iRIF containing 53BP1. RNF126 overexpression abolishes not only the formation of 53BP1 iRIF but also of RNF168, FK2, RAP80, and BRCA1. However, the iRIF formation of γH2AX, MDC1, and RNF8 is maintained, indicating that RNF126 acts between RNF8 and RNF168 during the DDR. In addition, RNF126 overexpression consistently results in the loss of RNF168-mediated H2A monoubiquitination at lysine 13/15 and inhibition of the non-homologous end joining capability. Taken together, our findings reveal that RNF126 is a novel factor involved in the negative regulation of DDR, which is important for sustaining genomic integrity.
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http://dx.doi.org/10.1074/jbc.M116.765602DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5767864PMC
January 2018

Immunoproteomic Identification of In Vivo-Produced Propionibacterium acnes Proteins in a Rabbit Biofilm Infection Model.

Clin Vaccine Immunol 2015 May 18;22(5):467-76. Epub 2015 Feb 18.

Department of Microbial Pathogenesis, School of Dentistry, University of Maryland, Baltimore, Baltimore, Maryland, USA Department of Microbiology and Immunology, School of Medicine, University of Maryland, Baltimore, Baltimore, Maryland, USA

Propionibacterium acnes is well-known as a human skin commensal but can also act as an invasive pathogen causing implant-associated infections. In order to resolve these types of P. acnes infections, the implants must be removed, due to the presence of an established biofilm that is recalcitrant to antibiotic therapy. In order to identify those P. acnes proteins produced in vivo during a biofilm infection, we established a rabbit model of implant-associated infection with this pathogen. P. acnes biofilms were anaerobically grown on dextran beads that were then inoculated into the left tibias of rabbits. At 4 weeks postinoculation, P. acnes infection was confirmed by radiograph, histology, culture, and PCR. In vivo-produced and immunogenic P. acnes proteins were detected on Western blot using serum samples from rabbits infected with P. acnes after these bacterial proteins were separated by two-dimensional gel electrophoresis. Those proteins that bound host antibodies were then isolated and identified by tandem mass spectrometry. Radiographs and histology demonstrated a disruption in the normal bone architecture and adherent biofilm communities in those animals with confirmed infections. A total of 24 immunogenic proteins were identified; 13 of these proteins were upregulated in both planktonic and biofilm modes, including an ABC transporter protein. We successfully adapted a rabbit model of implant-associated infection for P. acnes to identify P. acnes proteins produced during a chronic biofilm-mediated infection. Further studies are needed to evaluate the potential of these proteins for either a diagnostic test or a vaccine to prevent biofilm infections caused by P. acnes.
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http://dx.doi.org/10.1128/CVI.00760-14DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4412941PMC
May 2015

Ultrastructure and molecular phylogeny of Mesodinium coatsi sp. nov., a benthic marine ciliate.

J Eukaryot Microbiol 2015 Jan-Feb;62(1):102-20. Epub 2014 Aug 21.

Department of Biology, Chungnam National University, Daejeon, 305-764, Korea.

Mesodinium is a globally distributed ciliate genus forming frequent and recurrent blooms in diverse marine habitats. Here, we describe a new marine species, Mesodinium coatsi n. sp., originally isolated from interstitial water of surface sand samples collected at Mohang Beach, Korea. The species was maintained under a mixotrophic growth condition for longer than 1 yr by providing a cryptomonad, Chroomonas sp., as the sole prey. Cell morphology and subcellular structure were examined by light microscopy, scanning, and transmission electron microscopy, and molecular phylogeny was inferred from nuclear-encoded 18S rDNA sequence data. Like other Mesodinium species, M. coatsi consisted of two hemispheres separated by two types of kinetids, and had tentacles located at the oral end of the cell. Several food vacuoles were observed in the cytoplasm, and partially digested prey cells sometimes existed in food vacuoles. Kinetids and the associated accessory structures were quite similar to those previously reported, but M. coatsi was differentiated from other marine Mesodinium species by ultrastructural characters of the dikinetids, polykinetids, and tentacles. We also provided a detailed illustration of infraciliature. Molecular phylogeny revealed that M. coatsi and Mesodinium chamaeleon were closely related to each other.
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http://dx.doi.org/10.1111/jeu.12150DOI Listing
December 2015

A dinoflagellate Amylax triacantha with plastids of the cryptophyte origin: phylogeny, feeding mechanism, and growth and grazing responses.

J Eukaryot Microbiol 2013 Jul-Aug;60(4):363-76. Epub 2013 Apr 30.

LOHABE, Department of Oceanography, Chonnam National University, Gwangju 500-757, Korea.

The gonyaulacalean dinoflagellates Amylax spp. were recently found to contain plastids of the cryptophyte origin, more specifically of Teleaulax amphioxeia. However, not only how the dinoflagellates get the plastids of the cryptophyte origin is unknown but also their ecophysiology, including growth and feeding responses as functions of both light and prey concentration, remain unknown. Here, we report the establishment of Amylax triacantha in culture, its feeding mechanism, and its growth rate using the ciliate prey Mesodinium rubrum (= Myrionecta rubra) in light and dark, and growth and grazing responses to prey concentration and light intensity. The strain established in culture in this study was assigned to A. triacantha, based on morphological characteristics (particularly, a prominent apical horn and three antapical spines) and nuclear SSU and LSU rDNA sequences. Amylax triacantha grew well in laboratory culture when supplied with the marine mixotrophic ciliate M. rubrum as prey, reaching densities of over 7.5 × 10(3)  cells/ml. Amylax triacantha captured its prey using a tow filament, and then ingested the whole prey by direct engulfment through the sulcus. The dinoflagellate was able to grow heterotrophically in the dark, but the growth rate was approximately two times lower than in the light. Although mixotrophic growth rates of A. triacantha increased sharply with mean prey concentrations, with maximum growth rate being 0.68/d, phototrophic growth (i.e. growth in the absence of prey) was -0.08/d. The maximum ingestion rate was 2.54 ng C/Amylax/d (5.9 cells/Amylax/d). Growth rate also increased with increasing light intensity, but the effect was evident only when prey was supplied. Increased growth with increasing light intensity was accompanied by a corresponding increase in ingestion. In mixed cultures of two predators, A. triacantha and Dinophysis acuminata, with M. rubrum as prey, A. triacantha outgrew D. acuminata due to its approximately three times higher growth rate, suggesting that it can outcompete D. acuminata. Our results would help better understand the ecophysiology of dinoflagellates retaining foreign plastids.
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http://dx.doi.org/10.1111/jeu.12041DOI Listing
October 2013

Protein arginine methyltransferase 1 regulates herpes simplex virus replication through ICP27 RGG-box methylation.

Biochem Biophys Res Commun 2010 Jan 12;391(1):322-8. Epub 2009 Nov 12.

Department of Microbiology, Chungnam National University, Yuseong-gu, Daejon 305-764, Republic of Korea.

Protein arginine methylation is involved in viral infection and replication through the modulation of diverse cellular processes including RNA metabolism, cytokine signaling, and subcellular localization. It has been suggested previously that the protein arginine methylation of the RGG-box of ICP27 is required for herpes simplex virus type-1 (HSV-1) viral replication and gene expression in vivo. However, a cellular mediator for this process has not yet been identified. In our current study, we show that the protein arginine methyltransferase 1 (PRMT1) is a cellular mediator of the arginine methylation of ICP27 RGG-box. We generated arginine substitution mutants in this domain and examined which arginine residues are required for methylation by PRMT1. R138, R148 and R150 were found to be the major sites of this methylation but additional arginine residues serving as minor methylation sites are still required to sustain the fully methylated form of ICP27 RGG. We also demonstrate that the nuclear foci-like structure formation, SRPK interactions, and RNA-binding activity of ICP27 are modulated by the arginine methylation of the ICP27 RGG-box. Furthermore, HSV-1 replication is inhibited by hypomethylation of this domain resulting from the use of general PRMT inhibitors or arginine mutations. Our data thus suggest that the PRMT1 plays a key role as a cellular regulator of HSV-1 replication through ICP27 RGG-box methylation.
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http://dx.doi.org/10.1016/j.bbrc.2009.11.057DOI Listing
January 2010

Giant magneto-elastic coupling in multiferroic hexagonal manganites.

Nature 2008 Feb;451(7180):805-8

Department of Physics, SungKyunKwan University, Suwon 440-746, Korea.

The motion of atoms in a solid always responds to cooling or heating in a way that is consistent with the symmetry of the given space group of the solid to which they belong. When the atoms move, the electronic structure of the solid changes, leading to different physical properties. Therefore, the determination of where atoms are and what atoms do is a cornerstone of modern solid-state physics. However, experimental observations of atomic displacements measured as a function of temperature are very rare, because those displacements are, in almost all cases, exceedingly small. Here we show, using a combination of diffraction techniques, that the hexagonal manganites RMnO3 (where R is a rare-earth element) undergo an isostructural transition with exceptionally large atomic displacements: two orders of magnitude larger than those seen in any other magnetic material, resulting in an unusually strong magneto-elastic coupling. We follow the exact atomic displacements of all the atoms in the unit cell as a function of temperature and find consistency with theoretical predictions based on group theories. We argue that this gigantic magneto-elastic coupling in RMnO3 holds the key to the recently observed magneto-electric phenomenon in this intriguing class of materials.
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http://dx.doi.org/10.1038/nature06507DOI Listing
February 2008

Generalized synthesis of metal phosphide nanorods via thermal decomposition of continuously delivered metal-phosphine complexes using a syringe pump.

J Am Chem Soc 2005 Jun;127(23):8433-40

National Creative Research Center for Oxide Nanocrystalline Materials and the School of Chemical and Biological Engineering, Seoul National University, Seoul 151-744, Korea.

We synthesized uniform-sized nanorods of transition metal phosphides from the thermal decomposition of continuously delivered metal-phosphine complexes using a syringe pump. MnP nanorods with dimensions of 8 nm x 16 nm and 6 nm x 22 nm sized were synthesized by the thermal decomposition of Mn-TOP complex, which was prepared from the reaction of Mn(2)(CO)(10) and tri-n-octylphosphine (TOP), using a syringe pump with constant injection rates of 10 and 20 mL/h, respectively. When Co-TOP complex, which was prepared from the reaction of cobalt acetylacetonate and TOP, was reacted in a mixture solvent composed of octyl ether and hexadecylamine at 300 degrees C using a syringe pump, uniform 2.5 nm x 20 nm sized Co(2)P nanorods were generated. When cobaltocene was employed as a precursor, uniform Co(2)P nanorods with 5 nm x 15 nm were obtained. When Fe-TOP complex was added to trioctylphosphine oxide (TOPO) at 360 degrees C using a syringe pump and then allowed to age at 360 degrees C for 30 min, uniform-sized FeP nanorods with an average dimension of 12 nm x 500 nm were produced. Nickel phosphide (Ni(2)P) nanorods with 4 nm x 8 nm were synthesized successfully by thermally decomposing the Ni-TOP complex, which was synthesized by reacting acetylacetonate [Ni(acac)(2)] and TOP. We measured the magnetic properties of these nanorods, and some of the nanorods exhibited different magnetic characteristics compared to the bulk counterparts.
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http://dx.doi.org/10.1021/ja0427496DOI Listing
June 2005

One-nanometer-scale size-controlled synthesis of monodisperse magnetic iron oxide nanoparticles.

Angew Chem Int Ed Engl 2005 May;44(19):2873-7

National Creative Research Initiative Center for Oxide Nanocrystalline Materials and School of Chemical and Biological Engineering, Seoul National University, Seoul 151-744, Korea.

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http://dx.doi.org/10.1002/anie.200461665DOI Listing
May 2005
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