• The Korean Journal of Ecology
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• 제18권1호
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• pp.89-97
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• 1995

In order to study the successional trend and the heterogeneity of forest community, we investigated DBH frequency distribution of dominant tree species and the changes of several community indicies including ${\beta}-diversity\;({\beta}_t)$ along a belt transect in Mt. Yongam, Kwangnung Experimental Forest, which has been preserved for about 530 years. Quercus serrata, Carpinus laxiflora, and C. cordata were the three dominant species and their DBH frequency distribution showed a reverse J-shaped form, so these species seem to maintain by themselves. Dominancediversity curve had a lognormal distribution. d and H'for pooled quadrats were 0.13 and 1.09, respectively, but these indices within each quadiat varied with the range of 0.13 to 0.57 and 0.5 to 1.09, respectively. The value of ${\beta}_t$ along the belt transect ranged from 0.14 to 0.42. These results suggest that this forest community is in the stable climax stage but the components experience a heterogeneous microsuccession.

• 대한임상검사과학회지
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• 제37권3호
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• pp.149-154
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• 2005

대학병원의 임상검체에서 extended-spectrum-${\beta}$-lactamase (ESBL)생성 Klebsiella pneumoniae 51균주를 분리하였다. ESBL생성 K. pneumoniae 51균주는 광범위한 항생제에 내성을 보였고 대부분의 균주는 amikacin, gentamycin과 ciprofloxacin항생제에 내성을 나타내었다. 대학병원에서 분리한 51균주를 randomly amplified polymorphic DNA (RAPD)로 분석한 결과 충남대학병원 21균주와 충북대학병원에서 분리한 10균주는 Ia 와 Ib에 속하였고 경상대학 병원에서 분리한 20균주는 IIa, IIb에 속하였다. ESBL 생성 K. pneumoniae 51균주는 RAPD 분석으로 4가지의 유전형으로 구분 할 수 있었고 유전적으로 다양하였다. 이상의 결과로 RAPD 분석은 유전형분석에 빠르고 단순하고 경제적인 방법임을 알 수 있었다.

• Biomolecules & Therapeutics
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• 제31권2호
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• pp.141-147
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• 2023

Antibiotic resistance has emerged as a global threat to modern healthcare systems and has nullified many commonly used antibiotics. β-Lactam antibiotics are among the most successful and occupy approximately two-thirds of the prescription antibiotic market. They inhibit the synthesis of the peptidoglycan layer in the bacterial cell wall by mimicking the D-Ala-D-Ala in the pentapeptide crosslinking neighboring glycan chains. To date, various β-lactam antibiotics have been developed to increase the spectrum of activity and evade drug resistance. This review emphasizes the three-dimensional structural characteristics of β-lactam antibiotics regarding the overall scaffold, working mechanism, chemical diversity, and hydrolysis mechanism by β-lactamases. The structural insight into various β-lactams will provide an in-depth understanding of the antibacterial efficacy and susceptibility to drug resistance in multidrug-resistant bacteria and help to develop better β-lactam antibiotics and inhibitors.

• 한국미생물학회:학술대회논문집
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• 한국미생물학회 2008년도 International Meeting of the Microbiological Society of Korea
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• pp.118-118
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• 2008

The phylogenetic diversity of microbial communities in calcareous mats from Spearfish Creek, a freshwater stream located in the Black Hills of South Dakota, was examined using PCR-based 16S rDNA sequence analysis. In this study, two types of calcareous mats were compared: mature mats formed on the natural substrate of rock surfaces and developing mats on an artificial substrate of glass slides. Among 63 unique isolates from a clone library of 16S rRNA genes from mature mat samples, there were 8 phyla of Bacteria represented. The predominant phylum was Proteobacteria (48%), with the $\beta$ subclass being the largest group. Denaturing gradient gel electrophoresis (DGGE) analysis of 16S rRNA genes from slide samples collected at intervals for four months showed considerable diversity of the microbial community from the earliest stages of community development. Amplicons isolated from DGGE gels and sequenced indicated that community succession has occurred without increasing microbial diversity. However, light microscopic analysis revealed a significant increase in microbial cell density throughout the community development. Scanning electron microscopy of mat samples provides evidence that diatoms are also important members of calcareous mat communities.

• Journal of Periodontal and Implant Science
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• 제52권5호
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• pp.394-410
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• 2022

Purpose: The purpose of this study was to compare the microbial composition of 3 types of oral samples through 16S metagenomic sequencing to determine how to resolve some sampling issues that occur during the collection of sub-gingival plaque samples. Methods: In total, 20 subjects were recruited. In both the healthy and periodontitis groups, samples of saliva and supra-gingival plaque were collected. Additionally, in the periodontitis group, sub-gingival plaque samples were collected from the deepest periodontal pocket. After DNA extraction from each sample, polymerase chain reaction amplification was performed on the V3-V4 hypervariable region on the 16S rRNA gene, followed by metagenomic sequencing and a bioinformatics analysis. Results: When comparing the healthy and periodontitis groups in terms of alpha-diversity, the saliva samples demonstrated much more substantial differences in bacterial diversity than the supra-gingival plaque samples. Moreover, in a comparison between the samples in the case group, the diversity score of the saliva samples was higher than that of the supra-gingival plaque samples, and it was similar to that of the sub-gingival plaque samples. In the beta-diversity analysis, the sub-gingival plaque samples exhibited a clustering pattern similar to that of the periodontitis group. Bacterial relative abundance analysis at the species level indicated lower relative frequencies of bacteria in the healthy group than in the periodontitis group. A statistically significant difference in frequency was observed in the saliva samples for specific pathogenic species (Porphyromonas gingivalis, Treponema denticola, and Prevotella intermedia). The saliva samples exhibited a similar relative richness of bacterial communities to that of sub-gingival plaque samples. Conclusions: In this 16S oral microbiome study, we confirmed that saliva samples had a microbial composition that was more similar to that of sub-gingival plaque samples than to that of supra-gingival plaque samples within the periodontitis group.

• 운동영양학회지
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• 제25권4호
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• pp.24-37
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• 2021

[Purpose] To determine whether physical activity (PA), primarily the recommended 60 minutes of moderate-to-vigorous PA, is associated with gut bacterial microbiota in 10-year-old children. [Methods] The Block Physical Activity Screener, which provides minutes/day PA variables, was used to determine whether the child met the PA recommendations. 16S rRNA sequencing was performed on stool samples from the children to profile the composition of their gut bacterial microbiota. Differences in alpha diversity metrics (richness, Pielou's evenness, and Faith's phylogenetic diversity) by PA were determined using linear regression, whereas beta diversity (unweighted and weighted UniFrac) relationships were assessed using PERMANOVA. Taxon relative abundance differentials were determined using DESeq2. [Results] The analytic sample included 321 children with both PA and 16S rRNA sequencing data (mean age [SD] =10.2 [0.8] years; 54.2% male; 62.9% African American), where 189 (58.9%) met the PA recommendations. After adjusting for covariates, meeting the PA recommendations as well as minutes/day PA variables were not significantly associated with gut richness, evenness, or diversity (p ≥ 0.19). However, meeting the PA recommendations (weighted UniFrac R² = 0.014, p = 0.001) was significantly associated with distinct gut bacterial composition. These compositional differences were partly characterized by increased abundance of Megamonas and Anaerovorax as well as specific Christensenellaceae_R-7_group taxa in children with higher PA. [Conclusion] Children who met the recommendations of PA had altered gut microbiota compositions. Whether this translates to a reduced risk of obesity or associated metabolic diseases is still unclear.

• Journal of Ecology and Environment
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• 제48권2호
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• pp.120-127
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• 2024

Bats serve as vectors and natural reservoir hosts for various infectious viruses, bacteria, and fungi. These pathogens have also been detected in bat feces and can cause severe illnesses in hosts, other animals, and humans. Because pathogens can easily spread into the environment through bat feces, determining the bacterial communities in bat guano is crucial to mitigate potential disease transmission and outbreaks. This study primarily aimed to examine bacterial communities in the feces of insectivorous bats living in South Korea. Fecal samples were collected after capturing 84 individuals of four different bat species in two regions of South Korea, and the bacterial microbiota was assessed through next generation sequencing of the 16S rRNA gene. The results revealed that, with respect to the relative abundance at the phylum level, Myotis bombinus was dominated by Firmicutes (47.24%) and Proteobacteria (42.66%) whereas Miniopterus fuliginosus (82.78%), Rhinolophus ferrumequinum (63.46%), and Myotis macrodactylus (78.04%) were dominated by Proteobacteria. Alpha diversity analysis showed no difference in abundance between species and a significant difference (p < 0.05) between M. bombinus and M. fuliginosus. Beta-diversity analysis revealed that Clostridium, Asaia, and Enterobacteriaceae_g were clustered as major factors at the genus level using principal component analysis. Additionally, linear discriminant analysis effect size was conducted based on relative expression information to select bacterial markers for each bat species. Clostridium was relatively abundant in M. bombinus, whereas Mycoplasma_g10 was relatively abundant in R. ferrumequinum. Our results provide an overview of bat guano microbiota diversity and the significance of pathogenic taxa for humans and the environment, highlighting a better understanding of preventing emerging diseases. We anticipate that this research will yield bioinformatic data to advance our knowledge of overall microbial genetic diversity and clustering characteristics in insectivorous bat feces in South Korea.

• Asian-Australasian Journal of Animal Sciences
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• 제32권11호
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• pp.1734-1744
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• 2019

Objective: In this study, two glycosidases (XMosidases), ${\beta}$-xylosidase and ${\beta}$-mannosidase, were investigated on their in vitro hydrolysis activities of feed and on the improvement of growth performance in vivo in weanling pigs. Methods: Enzyme activities of XMosidases in vitro were evaluated in test tubes and simulation of gastric and small intestinal digestion, respectively, in the presence of NSPase. In vivo study was performed in 108 weaned piglets in a 28-d treatment. Pigs were allotted to one of three dietary treatments with six replicate pens in each treatment. The three treatment groups were as follows: i) Control (basal diet); ii) CE (basal diets+CE); iii) CE-Xmosidases (basal diets+ CE+${\beta}$-xylosidase at 800 U/kg and ${\beta}$-mannosidase at 40 U/kg). CE was complex enzymes (amylase, protease, xylanase, and mannanase). Results: In vitro XMosidases displayed significant activities on hydrolysis of corn and soybean meal in the presence of non-starch polysaccharide degrading enzymes (xylanase and ${\beta}$-mannanase). In vitro simulation of gastric and small intestinal digestion by XMosidases showed XMosidases achieved $67.89%{\pm}0.22%$ of dry matter digestibility and $63.12%{\pm}0.21%$ of energy digestibility at $40^{\circ}C$ for 5 hrs. In weanling pigs, additional XMosidases to CE in feed improved average daily gain, feed conversion rate (p<0.05), and apparent total tract digestibility of crude protein (p = 0.01) and dry matter (p = 0.02). XMosidases also altered the gut bacterial diversity and composition by increasing the proportion of beneficial bacteria. Conclusion: Addition of a complex enzyme supplementation (contained xylanase, ${\beta}$-mannanase, protease and amylase), XMosidases (${\beta}$-xylosidase and ${\beta}$-mannosidase) can further improve the growth performance and nutrient digestion of young pigs.

• 대한영양사협회학술지
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• 제21권2호
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• pp.110-122
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• 2015

The purpose of this study was to investigate the correlation between food behavior and Attention Deficit Hyperactivity Disorder (ADHD) score in elementary students in Suwon-si, Gyeonggi-do. Two hundreds and thirty two students (113 male and 119 female) in grades 4~6 participated. We assessed food behavior by using Nutrition Quotient (NQ). NQ was examined by an NQ questionnaire, which consisted of 19 food behavior checklist items. Their items were grouped into five categories: balance, diversity, moderation, regularity, and practice. All data were statistically analyzed by SPSS 18.0. Among the five factors, NQ for food behavior and balance factor showed the lowest score, whereas that of diversity factor showed the highest score. The final Nutrition Quotient (NQ) score weighted on such five factors was 62.59 points. The average level of ADHD by Conners-Wells Adolescent Self-Report Scale (Short Form) [CASS(S)] was 17.02 points out of a total of 81 points. Six students (2.2%) who scored more than 41 points were classified as ADHD risk. By gender, male students (19.76 points) showed a higher CASS(S) score than female students (14.41 points) did. There was a significant negative correlation between NQ and CASS(S) score (r=-0.445, P<0.001). Multiple regression determined the effects of moderation ($Exp({\beta})=-0.193$, P<0.01) and practice ($Exp({\beta})=-0.345$, P<0.001) on CASS(S) score. In conclusion, distinctive nutritional education is needed for students with a high level of ADHD to help their understanding considering their different levels of attention.

• 대한전자공학회논문지TC
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• 제37권1호
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• pp.76-87
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• 2000

멀티캐리어 DS-CDMA는 다중경로 페이딩 채널에서 광대역 시스템의 구현에 효과적인 방법이다. 본 논문에서는 콘볼류션 코딩을 적용한 중복된 멀티캐리어 DS-CDMA 시스템을 제안하고, 기존의 멀티캐리어 시스템과 비교하여 성능의 우수성을 입증한다. 제안된 멀티캐리어 DS-CDMA 시스템을 분할된 각 서브밴드를 가용주파수 대역 내에서 보다 효율적으로 구성하기 위하여 50% 중복 (overlapping) 된 구조를 갖도록 한다. 그리고 전송률이 1/M인 콘볼루션 채널코딩과 반복율이 1/R인 반복코딩을 적용하여 채널 코딩에 의한 이득과 주파수 다이버시티 (frequency diversity) 효과를 동시에 획득하고, 또한 MUI(Multiple User Interference)를 효과적으로 감소시키기 위하여 각 서브밴드의 확산신호에 raised-cosine 칩 성형필터를 적용하였다. 사용된 칩 성형필터의 rolloff 인자 (0< ${\beta}{\le}1$)의 변화에 따른 MUI를 분석하여 기존의 멀티캐리어 시스템의 성능보다 우수함을 보인다.