Biomedical subjects

Jeong-Woo Seo

Publications and source records attributed to Jeong-Woo Seo.

6 recordsLinked to original sources

PubMed2026

Webcam-Based Real-Time Visual Feedback During Baduanjin Practice in Older Adults: 6-Week Pilot Randomized Study.

BACKGROUND: Baduanjin qigong is a traditional mind-body exercise used to support balance and physical health in older adults. Age-related changes in proprioception may make accurate self-directed performance difficult without external guidance. OBJECTIVE: The aim of this study is to explore whether webcam-based real-time visual feedback delivered during supervised laboratory sessions was associated with differences in webcam-derived 2D pose discrepancy and movement consistency during Baduanjin practice in older adults. METHODS: A total of 31 older adults were enrolled, and 28 participants with complete analyzable records were included in this complete-case dataset (feedback group, n=14; nonfeedback group, n=14). All sessions were conducted face-to-face in a supervised motion-analysis laboratory. Weekly 2D pose-discrepancy values were analyzed using a linear mixed-effects model with fixed effects for group, categorical week, and the group-by-week interaction and a participant-specific random intercept. Joint- and movement-specific participant-level 6-week means were analyzed exploratorily using Welch independent-samples t tests. Holm correction was applied across 24 exploratory contrasts (6 week-specific, 8 joint-specific, and 10 movement-specific comparisons), and Hedges g and 95% CIs were reported. Participant-specific weekly slopes and within-participant variability were additionally examined to directly assess longitudinal error drift. RESULTS: The linear mixed-effects model showed no significant group-by-week interaction (Wald χ25=1.09; P=.96) and no significant overall week effect (Wald χ25=6.40; P=.27). Averaged across 6 weeks, the feedback group had an estimated mean 2D pose discrepancy 1.20° lower than the nonfeedback group (95% CI -2.38° to -0.02°; P=.046), although this marginal pilot finding was sensitive to an analytic approach. No week-specific contrast remained significant after Holm adjustment. Nominal right elbow, right shoulder, and right knee differences did not survive global Holm correction. Form 3 showed a lower mean discrepancy in the feedback group (mean difference -3.70°, 95% CI -5.86° to -1.54°; Hedges g=-1.30; unadjusted P=.002; Holm-adjusted P=.04). Direct analyses of participant-specific slopes and within-participant SDs did not support a significant between-group difference in longitudinal error drift. CONCLUSIONS: In this small exploratory pilot study conducted under supervised laboratory conditions, the 6-week trajectories did not differ significantly between groups. A marginally lower average 2D pose discrepancy was observed in the feedback group across the 6 weeks, but no individual week- or joint-specific comparison remained significant after multiplicity adjustment. Form 3 was the only exploratory contrast that remained significant after global Holm correction. Direct longitudinal analyses did not demonstrate prevention of error drift. Larger studies using validated reference measurements, prespecified outcomes, and adequately powered longitudinal designs are required.

Humans↗

PubMed2006

Thermolysis of isomigrastatin and its congeners via [3,3]-sigmatropic rearrangement: a new route to the synthesis of migrastatin and its analogues.

Thermolysis of isomigrastatin (1) under neat heating conditions afforded migrastatin (1a). The reaction is proposed to proceed via a concerted [3,3]-sigmatropic rearrangement by which ring expansion is achieved regio- and enantiospecifically. The general applicability of this reaction was demonstrated with six additional isomigrastatin congeners (3-8), providing a new route to the synthesis of migrastatin analogues (3a-8a). [reaction: see text]

Chromatography, High Pressure Liquid↗

PubMed2005

Iso-migrastatin congeners from Streptomyces platensis and generation of a glutarimide polyketide library featuring the dorrigocin, lactimidomycin, migrastatin, and NK30424 scaffolds.

Iso-Migrastatin (10) has been shown to be the main natural product of Streptomyces platensis, which undergoes a facile, H2O-mediated rearrangement into dorrigocin A (2), 13-epi-dorrigocin A (11), dorrigocin B (3), and migrastatin (1). Eight new congeners (12-19) of 10 were characterized. They can undergo the same H2O-mediated rearrangement into the corresponding 1, 2, 3, and 11 analogues (20-43) or 1,4-Michael addition with cysteine to afford the corresponding analogues (44-51) of NK30424 A and B (5, 6). This study generated a 47-member library of glutarimide polyketides, setting the stage to investigate the SAR for this family of natural products. These results also established the absolute stereochemistry of 5 and 6 and shed new light into the post-polyketide synthase steps for 10 biosynthesis.

Antibiotics, Antineoplastic↗

PubMed2002

Deprogrammed sporulation in Streptomyces.

The bacterial genus Streptomyces forms chains of spores by septation at intervals in aerial hyphae and subsequent maturation on solid medium. Substrate hyphae undergo extensive lysis, liberating nutrients on which aerial hyphae develop. Some mutant strains, however, ectopically form spores by septation in substrate hyphae on solid medium or in vegetative hyphae in liquid medium, which suggests that all hyphae have the potential to differentiate into spores. A Streptomyces griseus mutant strain NP4, which has a mutation in the regulatory system for an ATP-binding cassette (ABC) transporter gene, forms ectopic spores in substrate hyphae only on glucose-containing medium. In addition, overexpression of a substrate-binding protein of the ABC transporter in the wild-type strain causes ectopic septation in very young substrate hyphae and subsequent sporulation in response to glucose. These ectopic spores germinate normally. The ectopic sporulation is independent of A-factor, a microbial hormone that determines the timing of aerial mycelium formation during normal development. Thus, substrate hyphae of Streptomyces have a potential to develop into spores without formation of aerial hyphae. For programmed development, therefore, the strict repression of septum formation in substrate mycelium should be necessary, as well as the positive signal relay leading to aerial mycelium formation followed by septation and sporulation.

4-Butyrolactone↗

PubMed2002

ATP-binding cassette transport system involved in regulation of morphological differentiation in response to glucose in Streptomyces griseus.

Streptomyces griseus NP4, which was derived by UV mutagenesis from strain IFO13350, showed a bald and wrinkled colony morphology in response to glucose. Mutant NP4 formed ectopic septa at intervals along substrate hyphae, and each of the compartments developed into a spore which was indistinguishable from an aerial spore in size, shape, and thickness of the spore wall and in susceptibility to lysozyme and heat. The ectopic spores of NP4 formed in liquid medium differed from "submerged spores" in lysozyme sensitivity. Shotgun cloning experiments with a library of the chromosomal DNA of the parental strain and mutant NP4 as the host gave rise to DNA fragments giving two different phenotypes; one complementing the bald phenotype of the host, and the other causing much severe wrinkled morphology in the host. Subcloning identified a gene (dasR) encoding a transcriptional repressor belonging to the GntR family that was responsible for the reversal of the bald phenotype and a gene (dasA) encoding a lipoprotein probably serving as a substrate-binding protein in an ATP-binding cassette (ABC) transport system that was responsible for the severe wrinkled morphology. These genes were adjacent but divergently encoded. Two genes, named dasB and dasC, encoding a membrane-spanning protein were present downstream of dasA, which suggested that dasRABC comprises a gene cluster for an ABC transporter, probably for sugar import. dasR was transcribed actively during vegetative growth, and dasA was transcribed just after commencement of aerial hypha formation and during sporulation, indicating that both were developmentally regulated. Transcriptional analysis and direct sequencing of dasRA in mutant NP4 suggested a defect of this mutant in the regulatory system to control the expression of these genes. Introduction of multicopies of dasA into the wild-type strain caused ectopic septation in very young substrate hyphae after only 1 day of growth and subsequent sporulation in response to glucose. The ectopic spores of the wild type had a thinner wall than those of mutant NP4, in agreement with the observation that the former was sensitive to lysozyme and heat. Disruption of the chromosomal dasA or dasR in the wild-type strain resulted in growth as substrate mycelium, suggesting an additional role of these genes in aerial mycelium formation. The ectopic septation and sporulation in mutant NP4 and the wild-type strain carrying multicopies of dasA were independent of a microbial hormone, A-factor (2-isocapryloyl-3R-hydroxymethyl-gamma-butyrolactone), that acts as a master switch of aerial mycelium formation and secondary metabolism.

ATP-Binding Cassette Transporters↗

PubMed2002

Molecular characterization of the growth phase-dependent expression of the lsrA gene, encoding levansucrase of Rahnella aquatilis.

Expression of the lsrA gene from Rahnella aquatilis, encoding levansucrase, is tightly regulated by the growth phase of the host cell; low-level expression was observed in the early phase of cell growth, but expression was significantly stimulated in the late phase. Northern blot analysis revealed that regulation occurred at the level of transcription. The promoter region was identified by primer extension analysis. Two opposite genetic elements that participate in the regulation of lsrA expression were identified upstream of the lsrA gene: the lsrS gene and the lsrR region. The lsrS gene encodes a protein consisting of 70 amino acid residues (M(r), 8,075), which positively activated lsrA expression approximately 20-fold in a growth phase-dependent fashion. The cis-acting lsrR region, which repressed lsrA expression about 10-fold, was further narrowed to two DNA regions by deletion analysis. The concerted action of two opposite regulatory functions resulted in the growth phase-dependent activation of gene expression in Escherichia coli independent of the stationary sigma factor sigma(S).

Amino Acid Sequence↗