Biomedical subjects

Byung-Chun Kim

Publications and source records attributed to Byung-Chun Kim.

5 recordsLinked to original sources

PubMed2006

Stappia marina sp. nov., a marine bacterium isolated from the Yellow Sea.

A Gram-negative, aerobic and halophilic bacterium designated strain mano18T was isolated from a tidal flat area of Dae-Chun, Chung-Nam, Korea. This strain was motile by means of polar flagella, occasionally forming rosette-like aggregates, reduced nitrate to nitrite, required sodium ions for growth, exhibited catalase and oxidase activities and contained Q-10 as the major quinone and C(18 : 1)omega7c as the dominant cellular fatty acid. Analysis of the 16S rRNA gene sequence revealed that this strain is affiliated with a cluster within the Alphaproteobacteria. Strain mano18T synthesized bacteriochlorophyll under aerobic conditions. The 16S rRNA gene sequence similarity between strain mano18T and the most closely related species, Stappia aggregata DSM 13394T, was 98.5 %. Levels of DNA-DNA relatedness between strain mano18T and the type strains of S. aggregata and Stappia stellulata were respectively 6.2-11.2 and 3.3-7.6 %. Strain mano18T, like other Stappia strains, possesses carbon monoxide dehydrogenase genes. The results of DNA-DNA hybridization and the polyphasic data confirmed that strain mano18T can be considered to represent a novel taxon in the genus Stappia. The name Stappia marina sp. nov. is proposed for the tidal flat isolate; the type strain is strain mano18T (= KCTC 12288T = DSM 17023T).

Aldehyde Oxidoreductases↗

PubMed2005

Isolation of uncultivated anaerobic thermophiles from compost by supplementing cell extract of Geobacillus toebii in enrichment culture medium.

Several researchers have reported that microorganisms can be cultivated only in the presence of other microorganisms. We suggest that a portion of uncultivated microorganisms might be cultivated in the presence of cellular components released from bacteria in their natural environments. In this study, the cell extract of Geobacillus toebii was used to enrich uncultivated thermophiles from compost. In the process of enrichment cultures, cell extract supplementation apparently changed the community composition. This change was monitored by PCR-DGGE targeting 16S rRNA gene. Five novel groups of microorganisms (similarity of 16S rRNA gene to the closest relative <96%) were specifically isolated from enrichment cultures by using cell extract-supplemented culture media. Their growth was found to be dependent on the addition of extract of G. toebii. Putting these findings together, we suggest that the extracts of bacteria could be one of the growth factors in the thermal ecosystem with a possibility of extending other ecological niches.

Bacillaceae↗

PubMed2005

Average bioequivalence for two-sequence two-period crossover design with incomplete data.

A statistical procedure for analyzing a two-sequence two-period crossover design in bioequivalence trials is discussed when some observations at the second period are missing. The maximum likelihood estimators of the parameters in the average bioequivalence model are obtained under missing at random and a modified two one-sided test is proposed. The performances of the discussed test are compared using Monte Carlo simulations.

Cross-Over Studies↗

PubMed2004

Clostridium hastiforme is a later synonym of Tissierella praeacuta.

The previously proposed species Clostridium hastiforme and Tissierella praeacuta appear to be similar from their published descriptions. Accordingly, the aim of the current study was to perform phenotypic and genetic analyses of the type strains of both species, in order to clarify their taxonomic positions. The type strains of C. hastiforme (DSM 5675(T)) and T. praeacuta (NCTC 11158(T)) exhibited identical biochemical profiles and their 16S rRNA gene sequences displayed 99.9 % similarity. DNA-DNA hybridization was also estimated to be 96.5 %. Thus, it was concluded that C. hastiforme and T. praeacuta are synonyms, where T. praeacuta has priority. An emended description of the genus Tissierella is also given.

Clostridium↗

PubMed2003

Melatonin reduces ultraviolet-B induced cell damages and polyamine levels in human skin fibroblasts in culture.

UV radiation is known to cause photoaging of the skin and is considered one of the leading cause of developing skin carcinogenesis. Melatonin which has a highly lipophilic molecular structure facilitating penetration of cell membranes and serving as an extra- and intracellular free radical scavenger has been demonstrated to protect photodamage of skin affected by UV exposure. In this study, we have examined the role of melatonin in response to UVB induced photodamaging process, using human skin fibroblasts in vitro. Cell survival curves after UVB irradiation showed dose-dependent decrease. Only 60% of fibroblasts were survived at 140 mJ/cm(2) UVB irradiation. By pre-cultivation of cells with melatonin (100 nM), a significant number of cells remained unaffected. After UVB irradiation with 70 mJ/cm(2), the level of putrescine was 1.7+/-0.3 fold increased compared to melatonin pre-treated group. In Northern analyses, the transcriptional level of ornithine decarboxylase (ODC) gene expression was increased by UVB irradiation and prohibited by melatonin. These results indicated that melatonin was effectively able to neutralize membrane peroxidation when present in relevant concentration during UVB irradiation and diminishes the UVB-induced increase of polyamine synthesis and ODC gene expression. Collectively, ODC response to UVB induced changes are possibly involves a melatonin or antioxidant sensitive regulatory pathway in normal human skin fibroblast.

Antioxidants↗