• Fibers and Polymers
• /
• v.4 no.3
• /
• pp.107-113
• /
• 2003

The branched polypropylene (b-PP) was prepared by melt blending process with initiator, antioxidant, and functional monomers to improve the melt strength through the melt grafting. The melt flow index (MFI) of the b-PP was increased with increasing the initiator content. On the introduction of the alkylamine as the branching agents the MFI of the b-PP was increased, while that of the b-PP with the pentaerythritol triacrylate (PT) was decreased. It may be caused by the chain scission of the i-PP backbone due to the reduced thermal stability of the i-PP on the melt blending. The MFI of the b-PP without the antioxidant was increased due to the chain scission occurred during the melt processing, while on the introduction of the antioxidant, the MFI of the b-PP was decreased. The crystallization temperature of the b-PP was higher than that of PP, which was attributed to the branched chain structure. It was found that the PT was the most effective functional monomers for enhancing the melt properties of the b-PP.

• Journal of Microbiology and Biotechnology
• /
• v.22 no.9
• /
• pp.1288-1295
• /
• 2012

Exposure to bioaerosols causes various adverse health effects including infectious and respiratory diseases, and hypersensitivity. Controlling exposure to bioaerosols is important for disease control and prevention. In this study, we evaluated the efficacies of various functional filters coated with antimicrobial chemicals in deactivating representative microorganisms on filters or as bioaerosols. Tested functional filters were coated with different chemicals that included (i) Ginkgo and sumac, (ii) Ag-apatite and guanidine phosphate, (iii) $SiO_2$, ZnO, and $Al_2O_3$, and (iv) zeolite. To evaluate the filters, we used a model ventilation system (1) to evaluate the removal efficiency of bacteria (Escherichia coli and Legionella pneumophila), bacterial spores (Bacillus subtilis spore), and viruses (MS2 bacteriophage) on various functional filters, and (2) to characterize the removal efficiency of these bioaerosols. All experiments were performed at a constant temperature of $25^{\circ}C$ and humidity of 50%. Most bacteria (excluding B. subtilis) rapidly decreased on the functional filter. Therefore, we confirmed that functional filters have antimicrobial effects. Additionally, we evaluated the removal efficiency of various bioaerosols by these filters. We used a six-jet collision nebulizer to generate microbial aerosols and introduced it into the environmental chamber. We then measured the removal efficiency of functional filters with and without a medium-efficiency filter. Most bioaerosol concentrations did not significantly decrease by the functional filter only but decreased by a combination of functional and medium-efficiency filter. In conclusion, functional filters could facilitate biological removal of various bioaerosols, but physical removal of these by functional was minimal. Proper use of chemical-coated filter materials could reduce exposure to these agents.

• Maxillofacial Plastic and Reconstructive Surgery
• /
• v.32 no.6
• /
• pp.504-510
• /
• 2010

Purpose: This study was to examine the proliferation and function of the adipose tissue-derived endothelial cells according to different culture medium conditions. Materials and Methods: Adipose tissue-derived CD146 positive endothelial cells were cultured in according to different culture mediums (DMEM culture medium with or without osteogenic inductive agents and EBM-2 culture medium with or without osteogenic inductive agents). The proliferation and function of the adipose tissue-derived endothelial cells was examined in different culture medium conditions. Results: Adipose tissue-derived endothelial cells formed tube-like structures on Matrigel in EBM-2 culture medium with or without osteogenic inductive agents. However, the cells did not form tube-like structures on Matrigel in DMEM medium with or without osteogenic inductive agents. After 24 hours of culture, among the culture medium using EBM-2, the proliferation of the cells were promoted in EBM-2 medium without osteogenic inductive agents than in EBM-2 medium with osteogenic inductive agents. However, 72 hours of culture, the proliferation of the cells were promoted in EBM-2 medium with osteogenic inductive agents than in EBM-2 medium without osteogenic inductive agents. Conclusion: These results suggest that the proliferation and function of the adipose tissue-derived CD146 positive endothelial cells could be maintained in EBM-2 with osteogenic inductive agents.

• Korean Chemical Engineering Research
• /
• v.62 no.2
• /
• pp.142-146
• /
• 2024

There is growing interest in natural cosmetic ingredients as natural cosmetics become popular. As a part of effort to look for natureal cosmetic agent, seaweed Sargassums were tested for functional cosmetic agents. Effective materials were extracted from Sargassum coreanum. Sargassum hemiphyllum, and Sargassum patens by simple hot water extraction. Antioxidation, whitening, anti-wrinkle, UV absorption and anti-inflammation effects were studied for functional cosmetic agents. Sargassum extracts indicated excellent cell viability, strong anti-oxidation effect by DPPH radical scavenging activity and showed significant whitening effect from tyrosinase inhibition. However, effects of antiwrinkle, UV absorption and anti-inflammation were negligible. In conclusion, Sargassum coreanum extracts showed good possibility for anti-oxidation and whitening cosmetic agent.

• Korean Journal of Radiology
• /
• v.25 no.3
• /
• pp.257-266
• /
• 2024

Objective: To investigate molecular and functional consequences of additional exposures to iodine- or gadolinium-based contrast agents within 24 hours from the initial intravenous administration of iodine-based contrast agents through an animal study. Materials and Methods: Fifty-six Sprague-Dawley male rats were equally divided into eight groups: negative control, positive control (PC) with single-dose administration of CT contrast agent, and additional administration of either CT or MR contrast agents 2, 4, or 24 hours from initial CT contrast agent injection. A 12 µL/g of iodinated contrast agent or a 0.47 µL/g of gadolinium-based contrast agent were injected into the tail vein. Serum levels of blood urea nitrogen, creatinine, cystatin C (Cys C), and malondialdehyde (MDA) were measured. mRNA and protein levels of kidney injury molecule-1 (KIM-1) and neutrophil gelatinase-associated lipocalin (NGAL) were evaluated. Results: Levels of serum creatinine (SCr) were significantly higher in repeated CT contrast agent injection groups than in PC (0.21 ± 0.02 mg/dL for PC; 0.40 ± 0.02, 0.34 ± 0.03, and 0.41 ± 0.10 mg/dL for 2-, 4-, and 24-hour interval groups, respectively; P < 0.001). There was no significant difference in the average Cys C and MDA levels between PC and repeated CT contrast agent injection groups (Cys C, P = 0.256-0.362; MDA, P > 0.99). Additional doses of MR contrast agent did not make significant changes compared to PC in SCr (P > 0.99), Cys C (P = 0.262), and MDA (P = 0.139-0.771) levels. mRNA and protein levels of KIM-1 and NGAL were not significantly different among additional CT or MR contrast agent groups (P > 0.05). Conclusion: A sufficient time interval, probably more than 24 hours, between repeated contrast-enhanced CT examinations may be necessary to avoid deterioration in renal function. However, conducting contrast-enhanced MRI on the same day as contrast-enhanced CT may not induce clinically significant kidney injury.

• The Korean Journal of Pain
• /
• v.14 no.1
• /
• pp.83-92
• /
• 2001

Background: This study was undertaken to observe the functional changes of the hind limb and histopathological changes in the sciatic nerve after an injection of alcohol or phenol, which are commonly used neurolytic agents, highlighting the time of recovery. Methods: Forty-eight Sprague-Dawley rats weighing 200-300 g were used for the experiment. Histopathological changes under the electron microscope, were observed in the distal part of the sciatic nerve, into which 0.1 ml of alcohol or phenol was injected. This was severed in 3 rats of each group at 10 minutes, 1 hour, 24 hours, 3 days, 1, 2, 4 and 6 weeks later. The functional changes in the hind limbs were observed for 6 weeks by noting their walking pattern. Results: Following the injection of alcohol or phenol into the right sciatic nerve, the right hind limb showed a severe pronounced motor weakness and obvious gait changes. About 2 weeks later, gradual improvement of gait changes began, and after 6 weeks, the motor weakness and gait changes were no longer perceptible in both groups. The findings of any histopathological change were similar in both alcohol or phenol groups. At 10 minutes after injection, destructive lesions were confined to the unmyelinated fibers and the myelin sheath of small the myelinated fibers. On the 3rd day and at 1 week, pathologic changes in axonal fibers and Schwann cells were in being phagocytized in spite of myelin restitution. From 2 to 4 weeks, axonal regeneration and remyelination appeared at the same time a myelin disintegration and axonolysis. At 6 weeks, neural regeneration was similar to that of the contralateral control group. Conclusions: These results suggest that functional and histopathological changes, after injection of neurolytics into the peripheral nerves, are quite similar in both alcohol and phenol groups. The progression of functional and histopathological changes become more obvious according to the time interval following the injection. Consequently, side effects that develop following the use of alcohol or phenol may begin to improve around the time that nerve regeneration occurs, i.e., two to four weeks later.

• Microbiology and Biotechnology Letters
• /
• v.49 no.2
• /
• pp.167-173
• /
• 2021

Reactive oxygen species (ROS) disrupt the cellular redox balance, exert cytotoxic effects, and consequently promote the development of various diseases in humans. Previous studies have reported that antioxidants counteract the adverse effects of ROS. Several studies examine the whitening effects of various agents based on their ability to inhibit tyrosinase activity. Tyrosinase is a critical enzyme involved in the synthesis of melanin, which protects the skin against radiation. Various agents exhibiting antioxidant and tyrosinase inhibitory activities have been synthesized. However, these synthetic drugs are associated with toxicity, decreased safety, and poor skin penetration in vivo, which has limited the clinical application of synthetic drugs. This study examined the antioxidant and tyrosinase inhibitory activities of some microalgae. The methanol, dichloromethane, and ethyl acetate extracts of four microalgal species (Tetraselmis tetrathele, Dunaliella tertiolecta, Platymonas sp., and Chaetoceros simplex) were prepared. The physiological and whitening effects of microalgal extracts were investigated by measuring the antioxidant and tyrosinase inhibitory activities. The ethyl acetate extract of D. tertiolecta exhibited the highest antioxidant and tyrosinase inhibitory activities. Future studies must focus on examining the whitening effects of microalgae on cell lines to facilitate the development of microalga-based therapeutics for skin diseases, functional health foods, and whitening agents. Thus, microalgae have potential applications in the pharmaceutical, food, and cosmetic industries.

• Bulletin of the Korean Chemical Society
• /
• v.27 no.11
• /
• pp.1769-1774
• /
• 2006

A new liquid chromatographic chiral stationary phase based on (2S,3S)-O,O'-bis-(10-undecenoyl)-N,N'-bis-(3,5-dinitrobenzoyl)-2,3-diamino-1,4-butandiol was prepared starting from (2R,3R)-1,4-bis(benzyloxy)-2,3-butanediol. The new chiral stationary phase was applied to the resolution of racemic anilide derivatives of N-acetyl-a-amino acids, 1,1'-bi-2-naphthol and 3,3'-diaryl-1,1'-bi-2-naphthols. The CSP was also applied to the resolution of some chiral drugs including a diuretic, bendroflumethiazide, and non-steroidal anti-inflammatory agents such naproxen and alminoprofen. In every case, the chiral recognition efficiency of the new CSP was quite excellent.

• Biomolecules & Therapeutics
• /
• v.12 no.4
• /
• pp.202-208
• /
• 2004

Diabetes mellitus is a complex metabolic derangement with hyperglycaemia being the most characteristic symptom of diabetes. Hyperglycaemia can be caused by an increase in the rate of glucose production by the liver or by a decrease in the rate of glucose use by peripheral tissues. Impaired glucose transport is one of the major factors contributing to insulin resistance in type 2 diabetic patients. The ability of insulin to mediate tissue glucose uptake is a critical step in maintaining glucose homeostasis and in clearing the post-prandial glucose load. Glucose transport is mediated by specific carriers called glucose transporters (GLUTs). In this article, the functional importance and molecular mechanisms of insulin-induced glucose transport and development of hypoglycaemic agents which increase glucose transport are reviewed.

• Bulletin of the Korean Chemical Society
• /
• v.32 no.6
• /
• pp.1808-1846
• /
• 2011

From 1975 to 2011, for thirty six years, the author and his collaborators have developed a variety of reducing and hydroborating agents, and applied them to organic synthesis, which involves the 1,2-reduction of ${\alpha}$,${\beta}$-unsaturated carbonyl compounds, stereoselective reduction of cycloalkanones, regioselective ring-opening of epoxides, partial reduction of carboxylic acid derivatives to aldehydes, regioselective addition to carbon-carbon multiple bonds, etc. by utilizing metal hydrides and the newly-devised the Meerwein-Ponndorf-Verley (MPV) type reagents. Such developments provide a new synthetic methodology making possible valuable selective reductions and hydroborations, not practical previously.