Biomedical subjects

Hyun Choi

Publications and source records attributed to Hyun Choi.

6 recordsLinked to original sources

PubMed2006

Close-packed hemispherical microlens array from two-dimensional ordered polymeric microspheres.

This paper describes a facile, reproducible soft-lithography-based method for fabricating hexagonally close-packed microlens arrays by templating the surface of a colloidal monolayer, which is formed by spin-casting monodisperse polystyrene microspheres. The relief structure of colloidal monolayers has successfully generated PDMS elastomers with hexagonal arrays of hemispherical air voids. Closely packed hemispherical microlens arrays were imprinted on ultraviolet-curable photopolymers which are bound on glass substrates. Atomic force microscopy measurements showed that each spherical hole of the PDMS molds is 103 nm deep and the replicated microlens is 95 nm in height with narrow size distribution and good reproducibility. Without a multistep engineering process, this method might provide a reliable route to fabricate embossed thin layers ranging from nanometer to micrometers by controlling the size of polymer microspheres over a centimeter scale area.

Journal Article↗

PubMed2005

Yukmijihwang-tang derivatives enhance cognitive processing in normal young adults: a double-blinded, placebo-controlled trial.

Yukmijihwang-tang (YMJ), also known as Luweidihuang-tang in China, has been widely used as a general herbal tonic for hundreds of years in many Asian countries. This study examines whether YMJ derivatives (YMJd) enhance cognitive ability in normal human subjects and discusses its potential as treatment for dementia patients with deficient cognitive ability. Subjects were divided into two groups, the placebo-treated group (n = 15) and the YMJd-treated group (n = 20). K-WAIS tests, a Korean version of an individual intelligence quotient (IQ) test, and a P300 latency assessment of event-related potential (ERP) were conducted in order to measure changes in cognitive ability before and after 6 weeks of YMJd treatment. The K-WAIS mean scores of the group treated with YMJd were significantly higher than those of the placebo group (p < 0.05), and their mean P300 latency was substantially shorter (p < 0.005). These results suggest that YMJd treatment accelerates the speed of information processing and enhances cognitive ability. YMJd treatment may help dementia patients or the elderly recover from cognition deficiencies or degeneration in clinic.

Adolescent↗

PubMed2005

The anti-depressant effect of Nelumbinis semen on rats under chronic mild stress induced depression-like symptoms.

Nelumbinis Semen is a well-known traditional herbal medicine frequently used in treatment of depression in many Asian countries. In this study, its anti-depression effects in rats were investigated by comparing the test results of those treated with Nelumbinis Semen to those treated with other herbal anti-depressants, including Rehmanniae Radix Preparat, Corni Fructus, Lycii Fructus, Pinelliae Rhizoma and Hypericum Perforatum. In order to induce depression-like symptoms, the animals were placed under chronic mild stress in the form of overnight illumination for 2 consecutive days. They were treated with the respective herbal extract and forced swimming tests were conducted afterwards. The anti-depression effects of each extract were then evaluated based on a measured index, which consisted of struggling time, first latency and first rest duration. These test results show that Nelumbinis Semen provides greater anti-depression effects than the other herbal extracts. Specifically, only the rats treated with Nelumbinis Semen showed significant increases in struggling time (43.9%, p < 0.005, p = 0.0037) and in first latency time (90.2%, p < 0.05, p = 0.0116). However, the first rest duration for Nelumbinis Semen treated rats was not significantly different from the other rats. It appears that Nelumbinis Semen provides even greater anti-depression effects than Hypericum Perforatum (commonly referred to as St. John's Wort, perhaps the most widely used natural antidepressant today). The anti-depression effects of Nelumbinis Semen might be due to the modulation of the amount of neurotransmitters involved in depression.

Animals↗

PubMed2004

Suppression of IgE production and modulation of Th1/Th2 cell response by electroacupuncture in DNP-KLH immunized mice.

Effects of electroacupuncture (EA) on Th1/Th2 cell response were investigated in BALB/c mice immunized intraperitoneally with 2,4-dinitrophenylated keyhole limpet protein (DNP-KLH). Successive electroacupuncture stimulation on the ST36 acupoint was performed just after immunization. Serum levels of antigen-specific IgE and total IgE were significantly decreased compared with non-acupunctured controls. Production of the Th2-specific cytokines IL-4 and IL-13 in the anti-CD3 mAb-activated splenocytes was significantly suppressed in ST36 electroacupunctured mice compared with non-acupunctured mice. These results imply that successive electroacupuncture on ST36 can decrease the serum level of antigen-specific IgE and total IgE by suppression of the Th2 lineage development.

Animals↗

PubMed2004

Anti-obesity effect of PM-F2-OB, an anti-obesity herbal formulation, on rats fed a high-fat diet.

PM-F2-OB is one of the most well-known traditional herbal medicines that are frequently used for the treatment of obesity in Korea. The anti-obesity effect of PM-F2-OB on rats fed a high-fat diet was investigated through analyses of changes in body weight, kidney fat weight, and blood biochemicals including cholesterol, free fatty acid, BUN, creatinine, HDL, LDL, phospholipids, SGOT, SGPT, total lipids, and triglycerides. The subjects in this study were divided into four groups: a normal group with a standard diet (N); a PM-F2-OB treatment group fed a standard diet (N+PM-F2-OB); a control group fed a high-fat diet (C); and a PM-F2-OB treatment group fed a high-fat diet (C+PM-F2-OB). There were no significant differences in body weight change between the N and N+PM-F2-OB treatments. Also, there was no significant difference in the amount of food intake between the C and C+PM-F2-OB treatments. These results suggest that PM-F2-OB has no significant toxicity and does not induce a dislike for that diet due to its smell or taste. Rats were administered a high-fat diet (20% (w/w)) for six weeks to induce obesity. The study shows that PM-F2-OB significantly prevented increases in body weight, cholesterol, LDL and total lipids that resulted from the high-fat diet. PM-F2-OB also decreased kidney fat weight and free fatty acid, phospholipid, and triglyceride concentrations induced by the high-fat diet to level equals or below the normal diet group. It was concluded from the results that PM-F2-OB has a distinct anti-obesity effect.

Adipose Tissue↗

PubMed2004

So-Cheong-Ryong-Tang, tradititional Korean medicine, suppresses Th2 lineage development.

The present study was designed to evaluate the effect of So-Cheong-Ryong-Tang (SCRT, also called Sho-Seiryu-To or Xiao-Qing-Long-Tang) on helper T cell development by monitoring Th1/Th2-specific cytokine secretion patterns in artificially induced Th1 or Th2 polarized conditions. The results demonstrated that Th2 cells were dramatically underpopulated in the Th2-driven condition triggered by SCRT treatment, while the Th1 cells were not altered in the Th1-skewed condition. Furthermore, under Th2-skewed conditions the levels of interleukin-4 were considerably decreased with SCRT treatment. The expression of GATA-3, a transcription factor that plays a pivotal role in Th2 lineage programming, did not change with SCRT treatment, while the expression of another Th2 transcription factor, c-Maf, was dramatically suppressed. These data suggest that SCRT modulates Th2 development by suppressing c-Maf expression. This study implies that the SCRT effect on CD4(+) T cells is a key pharmacologic point of effect for treating IgE-mediated allergic asthma. These results also suggest that SCRT might be a useful agent for the correction of Th2-dominant pathologic disorders.

Animals↗