• Journal of Biomedical Engineering Research
• /
• v.45 no.4
• /
• pp.179-186
• /
• 2024

This paper investigates the impact of Riemannian Procrustes Analysis (RPA) on enhancing the classification performance of SPD-Net when applied to EEG signals across different sessions and subjects. EEG signals, known for their inherent individual variability, are initially transformed into Symmetric Positive Definite (SPD) matrices, which are naturally represented on a Riemannian manifold. To mitigate the variability between sessions and subjects, we employ RPA, a method that geometrically aligns the statistical distributions of these matrices on the manifold. This alignment is designed to reduce individual differences and improve the accuracy of EEG signal classification. SPD-Net, a deep learning architecture that maintains the Riemannian structure of the data, is then used for classification. We compare its performance with the Minimum Distance to Mean (MDM) classifier, a conventional method rooted in Riemannian geometry. The experimental results demonstrate that incorporating RPA as a preprocessing step enhances the classification accuracy of SPD-Net, validating that the alignment of statistical distributions on the Riemannian manifold is an effective strategy for improving EEG-based BCI systems. These findings suggest that RPA can play a role in addressing individual variability, thereby increasing the robustness and generalization capability of EEG signal classification in practical BCI applications.

• 한국생물공학회:학술대회논문집
• /
• 2003.10a
• /
• pp.341-345
• /
• 2003

Effect of immobilization on the production of human granulocyte-macrophage colony-stimulating factor (hGM-CSF) by Nicotiana tabacum cells was investigated using polyurethane foam as immobilization matrices. The cell activity and the hGM-CSF production were maintained for 16 days in spite of 3 times of media exchange. Under the same conditions of temperature and agitation rate, maximum concentrations of hGM-CSF in a 500-mL spinner flask and 100-mL Erleuneyer flasks were 17.3 ${\mu}g/L$ and 9.8 ${\mu}g/L$, respectively. Consequently high hGM-CSF production could be possible in spinner flask when the rate and amount of media exchange were optimized.

• Molecules and Cells
• /
• v.27 no.6
• /
• pp.629-634
• /
• 2009

G protein-coupled receptors (GPCRs) are part of multi-protein networks called 'receptosomes'. These GPCR interacting proteins (GIPs) in the receptosomes control the targeting, trafficking and signaling of GPCRs. PDZ domain proteins constitute the largest protein family among the GIPs, and the predominant function of the PDZ domain proteins is to assemble signaling pathway components into close proximity by recognition of the last four C-terminal amino acids of GPCRs. We present here a machine learning based approach for the identification of GPCR-binding PDZ domain proteins. In order to characterize the network of interactions between amino acid residues that contribute to the stability of the PDZ domain-ligand complex and to encode the complex into a feature vector, amino acid contact matrices and physicochemical distance matrix were constructed and adopted. This novel machine learning based method displayed high performance for the identification of PDZ domain-ligand interactions and allowed the identification of novel GPCR-PDZ domain protein interactions.

• Journal of Preventive Medicine and Public Health
• /
• v.42 no.6
• /
• pp.349-355
• /
• 2009

Biomarkers are characteristic biological properties that can be detected and measured in a variety of biological matrices in the human body, including the blood and tissue, to give an indication of whether there is a threat of disease, if a disease already exists, or how such a disease may develop in an individual case. Along the continuum from exposure to clinical disease and progression, exposure, internal dose, biologically effective dose, early biological effect, altered structure and/or function, clinical disease, and disease progression can potentially be observed and quantified using biomarkers. While the traditional discovery of biomarkers has been a slow process, the advent of molecular and genomic medicine has resulted in explosive growth in the discovery of new biomarkers. In this review, issues in evaluating biomarkers will be discussed and the biomarkers of environmental exposure, early biologic effect, and susceptibility identified and validated in epidemiological studies will be summarized. The spectrum of genomic approaches currently used to identify and apply biomarkers and strategies to validate genomic biomarkers will also be discussed.

• ALGAE
• /
• v.34 no.2
• /
• pp.99-109
• /
• 2019

Habitat-forming species increase spatial complexity and alter local environmental conditions, often facilitating the assembly of plants and animals. We conducted a trait-based approach to algal assemblages associated with the freshwater bryozoan, Pectinatella magnifica. Association with algae leads to the inner bodies of the bryozoans being colored green; this is frequently observed in the large rivers of South Korea. We collected the green-colored gelatinous matrices and phytoplankton from waterbodies of the two main rivers in South Korea. Algal assemblages within the colonies and in the waterbodies were compared using the three diversity indices (richness, diversity, and dominance), and the composition of functional groups (FGs) and morphologically based functional groups (MBFGs) between the colonies within and outside of P. magnifica colonies. The most dominant and common species within the colonies were Oscillatoria kawamurae and Pseudanabaena catenata, both of which were assigned to the same FG (codon S1). Of the algal assemblages within the colonies, the dominance was higher, while the richness and diversity were lower, than those in the waterbodies. There was variation in the compositions of FGs and MBFGs in the waterbodies outside the colonies. Total nitrogen and orthophosphate led to dominance, and were significant factors for the variation in FGs in the waterbodies, whereas there were no such significant factors within the colonies. This trait-based approach to the community structure of associated algae provides the status and habitat gradient of these communities, which are stable, isolated, and consistent with the overgrowth of shade-adapted tychoplanktonic cyanobacteria.

• Korean Journal of Environmental Agriculture
• /
• v.42 no.3
• /
• pp.220-230
• /
• 2023

Imidacloprid is a neonicotinoid insecticide widely used for insect control in a variety of crops. The evaluation of imidacloprid total residues in animal feeds derived from crop by-products is required to ensure the safety of livestock products. We performed simultaneous LC/MS/MS analyses of imidacloprid and its metabolites in five different livestock products including beef, pork, chicken, milk and egg from domestic markets. The methods for sample preparation and instrumental analysis were established by modifying QuEChERS method to meet the Codex guidelines. The methods generated 0.0035 mg/kg of the limit of determination (LOD), 0.01 mg/kg of the limit of quantitation (LOQ) and standard calibration linearity with >0.983 of the coefficients of determination (R²). The methods exhibited the recovery values of imidacloprid and its metabolites ranging from 65.66 to 119.27% without any interference between matrices. Imidacloprid total residues in the livestock products were found as values lower than the LOQ and maximum residue limits (MRLs). This study suggests that the methods are successfully applicable for the safety evaluation of imidacloprid total residues in livestock products from domestic markets.

• Journal of Biomedical Engineering Research
• /
• v.13 no.1
• /
• pp.55-64
• /
• 1992

AB -type block copolymers of poly($\tau$-benzyl L-glutamate) (PBLG, a segment) and polyoxypropylene (POP, Bsegment) were synthesized and they were reacted with polyoxypropylene his(6-aminohexyl) (POE) to enhance the hydrophilicity of the poly- mers. The degree of swelling of the POE -crosslinked block copolymers (CPB -2) was higher than that of the block dopolymers (PB). The amount of 5-fluorouracil re- leased from CPB-2 block copolymers was greater than that from the PB block copol- ymers when they were incubated in the same period. These results indicate that the amount of 5-fluorouracil released from the matrices is proportional to the hydrophilicity of the polymers. Observing polymer surfaces by scanning electron mi- croscope, pores (diameter ; $0.5-1.5{\mu}$m) were appeared on the surface of CPB-2

• Biomedical Science Letters
• /
• v.19 no.1
• /
• pp.25-31
• /
• 2013

Electrospun nanofibers are being widely used as a substratum for mammalian cell culture owing to their structural similarity to collagen fibers found in extracellular matrices of mammalian cells and tissues. Especially, development of diverse synthetic polymers has expanded use of electrospun nanofibers for constructing cell culture substrata. Synthetic polymers have several benefits comparing to natural polymer for their structural consistency, low cost, and capability for blending with other polymers or small molecules to enhance their structural integrity or add biological functions. PMGI (polymethylglutarimide) is one of the synthetic polymers that produced a rigid nanofiber that enables incorporation of small molecules, peptides, and gold nanoparticles through co-electrospinning process, during which the materials are fixed without any chemical modifications in the PMGI nanofibers by maintaining their activities. Using the phenomenon of PMGI nanofiber, here I introduce a construction method of a nanofiber substratum having cell-affinity function towards a pluripotent stem cell by incorporating a small molecule in the PMGI nanofiber.

• Journal of Biomedical Engineering Research
• /
• v.9 no.1
• /
• pp.37-46
• /
• 1988

Synthetic biodegradable polymers are of great interest for biomedical applications such as surgical sutures and drug delivery systems. The copolymers of ${alpha}-amino$ acids and ${alpha}-hydroxy$ matrices having the required permeability for drugs. Poly (glycine.co-lactic acid) and poly (glycine-co-glycolic acid) have been synthesized by ring-opening polymerization. Morpholine-2, 5-diane, lactide, and glycolid have been used as starting materials for polydepsipeptides. The synthesized monomers and copoylmers have been identified by NMR and FT-lR spectrophotometer. The thermal properties and glass transition temperatures ($T_g$) of the copolymers have been measured by differential scanning calorimetry. The $T_g$ values of poly (glycine-co-lactic acid) and poly (glycine co.glycolic acid) are increased with increasing mole fraction of morpholine-2, 5-dione in the copolymers.

• Molecular & Cellular Toxicology
• /
• v.4 no.4
• /
• pp.311-317
• /
• 2008

Zebrafish were exposed to commercial silver nanoparticles (${\sim}$10-20 nm) at 0.4 and 4 ppm during cadual fin regeneration. The silver was in the $Ag^+$ ionic form. Fin regeneration was slow in the group exposed to the lower concentration. The cadual fin, gill, and muscle were assayed after 48 hours and subjected to histological analysis. In all tissues sampled, fish exposed to nanoparticles exhibited infiltration, large mitochondria with empty matrices, and accumulation of nano-sized silver in blood vessels. The results suggested mitochondrial damage and induction of inflammation. Microarray analysis of RNA from young zebrafish (52 hours post-fertilization) that were exposed to nanometer-sized silver particles, showed alteration in expression of the p53 gene pathway related to apoptosis. Gene expression changes in the nanoparticle-treated zebrafish led to phenotypic changes, reflecting increased apoptosis.