• Journal of the Korean Wood Science and Technology
• /
• 제36권5호
• /
• pp.33-41
• /
• 2008

This study was aimed to develop the knot quantification method to predict bending strength, using x-ray scanner. The bending strength prediction model was proposed in this paper. The model was based on Knot Depth Ratio (KDR) and closely-spaced knot was taken into account. The previous paper reported that KDR is the ratio of the knot and transit zone to the lumber thickness. Even though KDR involves transit zone, it was verified that the ratio of the moment of inertia for knot to gross cross section ($I_k/I_g$) based on KDR was a good predictor for bending strength of lumber. To take closely-spaced knot into account, a projection method was also proposed. This projection method improved the predictive accuracy significantly. It showed coefficient of determinant of 0.65 and root mean square error (RMSE) of 9.17.

• Reproductive and Developmental Biology
• /
• 제35권1호
• /
• pp.9-15
• /
• 2011

The functional cardiovascular system is comprised of distinct mesoderm-derived lineages including endothelial cells, vascular smooth muscle cells and other mesenchymal cells. Recent studies in the human embryonic stem cell differentiation model have provided evidence indicating that these cell lineages are developed from the common progenitors such as hemangioblasts and cardiovascular progenitor cells. Also, the studies have suggested that these progenitors have a common primordial progenitor, which expresses KDR (human Flk-1, also known as VEGFR2, CD309). We demonstrate here that sustained activation of BMP4 (bone morphogenetic protein 4) in hESC line, CHA15 hESC results in $KDR^+$ mesoderm specific differentiation. To determine whether the $KDR^+$ population derived from hESCs enhances potential to differentiate along multipotential mesodermal lineages than undifferentiated hESCs, we analyzed the development of the mesodermal cell types in human embryonic stem cell differentiation cultures. In embryoid body (EB) differentiation culture conditions, we identified an increased expression of $KDR^+$ population from BMP4-stimulated hESC-derived EBs. After induction with additional growth factors, the $KDR^+$ population sorted from hESCs-derived EBs displays mesenchymal, endothelial and vascular smooth muscle potential in matrix-coated monolayer culture systems. The populations plated in monolayer cultures expressed increased levels of related markers and exhibit a stable/homologous phenotype in culture terms. In conclusion, we demonstrate that the $KDR^+$ population is stably isolated from CHA15 hESC-derived EBs using BMP4 and growth factors, and sorted $KDR^+$ population can be utilized to generate multipotential mesodermal progenitors in vitro, which can be further differentiated into cardiovascular specific cells.

• 한국수정란이식학회지
• /
• 제32권3호
• /
• pp.87-94
• /
• 2017

Tissue engineering (TE) has been developed to create functional organs and tissue by combining 3D matrix and cells in vitro. Vascularization and angiogenesis are utmost important for supply of nutrients and oxygen in tissue engineered organs. The present study was performed to isolate and characterize primary endothelial cells (EC) from aorta of alpha 1, 3-enzyme galactosyltransferase knock out (GalT KO) pig, to minimize immune rejection and analyze body immune system for future xenotransplantation studies. Isolation of primary EC from aorta were performed by incubation with dispase for 8-10 min at $37^{\circ}C$. Primary EC were cultured in EC growth medium on different extra cellular matrix (ECM), either collagen or gelation. Primary EC exhibits morphological characteristics and showed positive expressions of EC specific marker proteins i.e. PECAM1, KDR and VWF despite of their ECM surface; however, on collagen based surface they showed increase in mRNA level analyzed by qPCR. Primary EC cultured on collagen were sorted by flow cytometer using KDR marker and cultured as KDR positive cells and KDR negative cells, respectively. KDR positive cells showed dramatically increased in PECAM1 and VWF level as compared to KDR negative cells. Based on the above results, primary EC derived from GalT KO are successfully isolated and survived continuously in culture without becoming overgrown by fibroblast. Therefore, they can be utilize for xeno organ transfer, tissue engineering, and immune rejection study in future.

• Archives of Pharmacal Research
• /
• 제28권11호
• /
• pp.1270-1274
• /
• 2005

The vascular endothelial growth factor (VEGF) plays a key role in angiogenesis, which is a process where new blood vessels develop from the endothelium of a pre-existing vasculature. VEGF exerts its activity by binding to its receptor tyrosine kinase, KDR/Flk-1, which is expressed on the surface of endothelial cells. A methanol extract and organic solvent (n-hexane, ethyl acetate, n-butanol, aqueous) fractions from Rubus coreanus were examined for their inhibitory effects on VEGF binding to the VEGF receptor. The methanol extract from the crude drug were found to significantly inhibit VEGF binding to the VEGF receptor ($IC_{50}$$\thickapprox$27 $\mu$g/mL). Among the fractions examined, the aqueous fraction from the medicinal plant showed potent inhibitory effects against the binding of KDR/Flk-1-Fc to immobilized $VEGF_{165}$ in a dose­dependent manner ($IC_{50}$$\thickapprox$11 $\mu$g/mL). Sanguiin H-6 was isolated as an active principle from the aqueous fraction, and inhibited the binding of KDR/Flk-1-Fc to immobilized $VEGF_{165}$ in a dose­dependent manner ($IC_{50}$$\thickapprox$0.3 $\mu$g/mL). In addition, sanguiin H-6 efficiently blocked the VEGF­induced HUVEC proliferation in a dose-dependent manner ($IC_{50}$$\thickapprox$7.4 $\mu$g/mL) but had no effect on the growth of HT1080 human fibrosarcoma cells. This suggests that sanguiin H-6 might be a potential anti-angiogenic agent.

• Natural Product Sciences
• /
• 제13권2호
• /
• pp.128-131
• /
• 2007

Tumor angiogenesis is a critical step f3r the growth and metastasis of solid tumors. Vascular endothelial growth factor (VEGF) is the most important angiogenic molecule associated with tumor-induced neovascularization. VEGF exerts its activity through binding to its receptor tyrosine kinase, KDR/Flk-1, expressed on the surface of endothelial cells. This study was carried out to investigate inhibitory effect of extracts from root cortex of Paeonia suffruticosa Andrews on VEGF binding to VEGF receptor. The MeOH extract from P. suffrutiocosa Andr. inhibited the binding of KDR/Flk-1-Fc to immobilized VEGF$_{165}$ more than 45% at the concentration of 100 ${\mu}$g/mL. The MeOH extract was further fractionated into n-hexane, ethyl acetate, n-BuOH, and aqueous fractions. Among the four fractions, the ethyl acetate fraction from the root cortex of P. suffruticosa Andr. exhibited highly effective inhibition (${\approx}$ 79% inhibition) and then n-BuOH fraction (${\approx}$ 45% inhibition) on the binding of KDR/Flk-1-Fc to immobilized VEGF$_{165}$ at the concentration of 100 ${\mu}$g/mL. The ethyl acetate fraction from the root cortex of P. suffruticosa Andr. more efficiently blocked VEGF-induced human umbilical vein endothelial cell proliferation, than the growth of HT1080 human fibrosarcoma. Our results suggest that P. suffruticosa Andr. may be used as a candidate fur developing anti-angiogenic agent.

• Parasites, Hosts and Diseases
• /
• 제60권3호
• /
• pp.217-221
• /
• 2022

The head louse Pediculus humanus capitis (De Geer) is a hematophagous ectoparasite that inhabits the human scalp. The infestations are asymptomatic; however, skin irritation from scratching occasionally may cause secondary bacterial infections. The present study determined the presence and frequency of the knockdown resistance (kdr) mutation T929I in 245 head lice collected from Mexico, Peru, and Canada. Head lice were collected manually using a comb in the private head lice control clinic. Allele mutation at T9291 was present in 100% of the total sampled populations (245 lice) examined. In addition, 4.89% of the lice were homozygous susceptible, whereas 6.93% heterozygous and 88.16% homozygous were resistant, respectively. This represents the second report in Mexico and Quebec and fist in Lima.

• 전기의세계
• /
• 제61권9호
• /
• pp.16-21
• /
• 2012

• Parasites, Hosts and Diseases
• /
• 제62권2호
• /
• pp.251-256
• /
• 2024

The global resurgence of bed bug infestations, exacerbated by increasing international travel, trade, and insecticide resistance, has significantly impacted Korea. This study identified the bed bug species and performed pyrethroid resistance genotyping of recently resurgent bed bugs in Korea. Thirty-one regional bed bug samples were collected from 5 administrative regions: Gyeonggi-do (n=14), Seoul (n=13), Busan (n=2), Jeonllanam-do (n=1), and Chungcheongbuk-do (n=1). The samples underwent morphological and molecular identification. Twenty-four regional samples (77.4%) were identified as the tropical bed bug, Cimex hemipterus, and the remaining 7 regional samples (22.6%) were identified as the common bed bug, Cimex lectularius. The C. hemipterus regional samples carried at least three mutations associated with knockdown resistance (kdr), including 2 super-kdr mutations. The 7 C. lectularius regional samples possessed at least one of the 3 kdr-related mutations associated with pyrethroid resistance. This study confirms that the prevalent bed bug species recently in Korea is C. hemipterus, replacing the previously endemic C. lectularius. Additionally, the rise in bed bug populations with pyrethroid resistance underscores the necessity of introducing alternative insecticides.

• Parasites, Hosts and Diseases
• /
• 제58권6호
• /
• pp.709-714
• /
• 2020

Knockdown resistance (kdr) mutations in the voltage-gated sodium channel (VGSC) of mosquitoes confer resistance to insecticides. Although insecticide resistance has been suspected to be widespread in the natural population of Aedes aegypti in Myanmar, only limited information is currently available. The overall prevalence and distribution of kdr mutations was analyzed in Ae. aegypti from Mandalay areas, Myanmar. Sequence analysis of the VGSC in Ae. aegypti from Myanmar revealed amino acid mutations at 13 and 11 positions in domains II and III of VGSC, respectively. High frequencies of S989P (68.6%), V1016G (73.5%), and F1534C (40.1%) were found in domains II and III. T1520I was also found, but the frequency was low (8.1%). The frequency of S989P/V1016G was high (55.0%), and the frequencies of V1016G/F1534C and S989P/V1016G/F1534C were also high at 30.1% and 23.5%, respectively. Novel mutations in domain II (L963Q, M976I, V977A, M994T, L995F, V996M/A, D998N, V999A, N1013D, and F1020S) and domain III (K1514R, Y1523H, V1529A, F1534L, F1537S, V1546A, F1551S, G1581D, and K1584R) were also identified. These results collectively suggest that high frequencies of kdr mutations were identified in Myanmar Ae. aegypti, indicating a high level of insecticide resistance.

• Parasites, Hosts and Diseases
• /
• 제58권5호
• /
• pp.543-550
• /
• 2020

Mosquitoes are globally distributed and important vectors for the transmission of many human diseases. Mosquito control is a difficult task and the cost of preventing mosquito-borne diseases is much lower than that for curing the associated diseases. Thus, chemical control remains the most effective tool for mosquito. Due to the long-term intensive use of insecticides to control mosquito vectors, resistance to most chemical insecticides has been reported. This study aimed to investigate the relationship between insecticide resistance and target site mutation of L1014 kdr and G119 ace alleles in 5 species/species group of mosquitoes (Aedes vexans, Ae. albopictus, Anopheles spp., Culex pipiens complex, and Cx. tritaeniorhynchus) obtained from 6 collection sites. For Anopheles spp., the proportion of mosquitoes with mutated alleles in L1014 was 88.4%, homozygous resistant genotypes were observed in 46.7%, and heterozygous resistant genotypes were observed in 41.8%. For the Cx. pipiens complex and Cx. tritaeniorhynchus species, homozygous resistant genotypes were found in 25.9% and 9.8%, respectively. However, target site mutation of L1014 in the Ae. vexans nipponii and Ae. albopictus species was not observed. Anopheles spp., Cx. pipiens complex, and Cx. tritaeniorhynchus mosquitoes were resistant to deltamethrin and chlorpyriphos, whereas Ae. vexans nipponii and Ae. albopictus were clearly susceptible. We also found a correlation between the resistance phenotype and the presence of the L1014 kdr and G119 ace mutations only in the Anopheles spp. population. In this study, we suggest that insecticide resistance poses a growing threat and resistance management must be integrated into all mosquito control programs.