Biomedical subjects

S Y Yoon

Publications and source records attributed to S Y Yoon.

45 records · Page 3Linked to original sources

PubMed1998

Cinnamaldehyde inhibits lymphocyte proliferation and modulates T-cell differentiation.

Two kinds of cinnamaldehyde derivative, 2'-hydroxycinnamaldehyde (HCA) and 2'-benzoxy-cinnamaldehyde (BCA), were studied for their immunomodulatory effects. These compounds were screened as anticancer drug candidates from stem bark of Cinnamomum cassia for their inhibitory effect on farnesyl protein transferase activity. Ras activation, which is accompanied with its farnesylation, has been known to be important in immune cell activation as well as in carcinogenesis. Treatment of these cinnamaldehydes to mouse splenocyte cultures induced suppression of lymphoproliferation following both Con A and LPS stimulation in a dose-dependent manner. A dose of I microM of HCA and BCA inhibited the Con A-stimulated proliferation by 69% and 60%, and the LPS-induced proliferation by 29% and 21%, respectively. However, the proliferation induced by PMA plus ionomycin was affected by neither HCA nor BCA treatment. Decreased levels of antibody production by HCA or BCA treatment were observed in both SRBC-immunized mice and LPS-stimulated splenocyte cultures. The exposure of thymocytes to HCA or BCA for 48 h accelerated T-cell differentiation from CD4 and CD8 double positive cells to CD4 or CD8 single positive cells. The inhibitory effect of cinnamaldehyde on lymphoproliferation was specific to the early phase of cell activation, showing the strongest inhibition of Con A- or LPS-stimulated proliferation when added concomitantly with the mitogens. In addition, the treatment of HCA and BCA to splenocyte cultures attenuated the Con A-triggered progression of cell cycle at G1 phase with no inhibition of S to G2/M phase transition. Although cinnamaldehyde treatment had no effect on the IL-2 production by splenocyte cultures stimulated with Con A, it inhibited markedly and dose-dependently the expression of IL-2Ralpha and interferon-gamma. Taken together, the results in this study suggest both HCA and BCA inhibit the lymphoproliferation and induce a T-cell differentiation through the blockade of early steps in signaling pathway leading to cell growth.

Adjuvants, Immunologic↗

PubMed1998

A case of Wegener's granulomatosis complicated by diffuse pulmonary hemorrhage and thrombotic thrombocytopenic purpura.

Wegener's granulomatosis is a distinct form of necrotizing granulomatous vasculitis which usually affects the kidneys and the upper and lower respiratory tracts. Unusual manifestations have also been reported, and these include colitis, urethritis and diabetes insipidus. We describe a case of Wegener's granulomatosis which presented with rapidly progressive renal insufficiency, sudden deafness, red eye, facial palsy, and complicated by uncommon manifestations that were diffuse pulmonary hemorrhage and thrombotic thrombocytopenic purpura.

Aged↗

PubMed1997

A screening method of SH2 domain ligands and blockers using a solid phase binding.

We have developed a high throughput screening method for SH2 domain binding ligands and blockers. This method measures directly the binding of a 3H-labeled phosphopeptide derived from the sequence around tyrosine317 in the human Shc (SpYVNVK) to the SH2 domain of Grb2, which is precoated as glutathione S-transferase fusion proteins on solid phase. The optimum concentration for the fusion protein coating was 300 ng/100 microl/well for SH2 domain binding. Although an 8-h incubation at 4 degrees C for the coating of fusion protein was required to reach a maximum binding, even a 2-h coating produced 84% of the maximum binding. Saturation of ligand peptide binding in our assay system was observed at 10 pmol/well for the SH2 domain. However, 2 pmol/well showed consistent and reproducible results for the binding when the incubations were performed for 8 h at 4 degrees C. Competitive binding inhibition studies with various unlabeled phosphopeptides imply that the binding assay is highly specific to peptide sequences and able to screen possible ligands or blockers of signal transduction pathway mediated by Grb2 SH2 binding. In conclusion, our new method for SH2 domain binding is easy, rapid, and most of all inexpensive. These advantages over existing assay methods make this method especially suitable for a high throughput application, such as the screening for anticancer drug candidates.

Adaptor Proteins, Signal Transducing↗

PubMed1997

Dynamin II associates with Grb2 SH3 domain in Ras transformed NIH3T3 cells.

Grb2, a linker protein containing two SH3 domains and one SH2 domain, is known as an essential element of the Ras pathway in multiple systems. One of the functions of Grb2 is to link tyrosine-phosphorylated receptors to downstream effector proteins via the SH2 and SH3 domain bindings. To identify Grb2-associated proteins in Ras transformed NIH3T3 cells, we performed coprecipitation experiments using recombinant GST-Grb2 fusion proteins and found a remarkably strong band of 100 kDa. With N-terminal amino acid sequencing, we identified the protein of 100 kDa as dynamin II. Dynamin II was also observed in the coprecipitates with the GST fusion protein of N-SH3 or C-SH3 domain of Grb2 but not in that of Grb2 SH2 domain. The SH3-mediated association of Grb2 with dynamin II was confirmed by competitive binding experiments with oligopeptides whose sequence corresponded to that of SH2 or SH3 binding motif. The dynamin II coprecipitation was completely abrogated by the addition of the oligopeptide of SH3 binding motif, but addition of SH2 binding motif had no effect. In conclusion, these results suggest that dynamin II may be largely expressed and closely associated with Grb2-mediated signaling in Ras transformed cells.

3T3 Cells↗

PubMed1997

Fc epsilon RI-ligation induces association of tyrosine phosphorylated proteins with Src homology 2 domains of phospholipase C gamma 1 in RBL-2H3 rat basophilic leukemia cells.

Stimulation of the IgE receptors on mast cells and basophils activates protein tyrosine kinases and phospholipases leading to histamine release. However, the mechanism by which protein tyrosine kinases regulate the phospholipases is not clearly defined yet. In this study, we examined the possibility that phospholipase C gamma 1 associates with protein tyrosine kinases and tyrosine phosphorylated molecules as a result of activation of RBL-2H3 cells, and that this association involves the Src homology 2 domains of phospholipase C gamma 1. An increase in cytoplasmic Ca2+ level and tyrosine phosphorylations of proteins, including 72 and 40 kDa proteins, were observed after the cross-linking of the IgE receptors on RBL-2H3 rat basophilic cells by dinitrophenyl-specific IgE and dinitrophenyl-conjugated human serum albumin. Immunoprecipitation and coprecipitation experiments were performed to determine if the activation of protein tyrosine kinases is linked to the activation of phospholipase C gamma 1 via its SH2 domains. Tyrosine phosphorylation of phospholipase C gamma 1 was observed in 1 min following IgE receptor stimulation. several proteins (72, 50, 40, and 33 kDa) were identified to be tyrosine phosphorylated and specifically associated with phospholipase C gamma 1 by its Src homology 2 domains. In addition, the coprecipitated complex contains the tyrosine kinase activity which phosphorylates 72, 40, and 33 kDa proteins in the complex. In conclusion, these studies establish that tyrosine-phosphorylated proteins of 72, 40, and 33 kDa associate with phospholipase C gamma 1 via its SH2 domains following IgE receptor stimulation of RBL-2H3 basophilic cells, implying that protein tyrosine kinases may tyrosine-phosphorylate and recruit signaling proteins around the phospholipase C gamma 1 and that phospholipase C gamma 1 activation induces calcium mobilization, PKC activation and degranulation in mast cells or basophils.

Animals↗

PubMed1996

[Comparison of percutaneous manual and endoscopic laser diskectomy with chemonucleolysis and automated nucleotomy].

The combination of percutaneous manual and endoscopic Ho:YAG laser discectomy (PELD) is a new minimal intervention technique in treating patients with herniated lumbar discs that do not penetrate the posterior longitudinal ligament. The results in 100 patients treated with PELD were compared randomly with those in 100 patients treated by chemonucleolysis with chymopapain (CN) and 100 patients treated by automated percutaneous lumbar discectomy (APLD) at the same hospital. We followed the 300 patients postoperatively for 1 year, with physical examination, postoperative plain lumbosacral radiography, CT, MRI and a self-assessment questionnaire. Some 68% of the patients in the PELD group considered the outcome as excellent or good and 23% as fair; the corresponding figures were 55% and 27% in the CN group, and 48% and 32% in the APLD group. Nine percent of the patients in the PELD group underwent open microdiscectomy or were suffering from back pain with sciatica, compared with 18% in the CN group and 20% in the APLD group. PELD showed better extraction of the hernia mass than APLD and a lower rate of low back pain and less decrease in disc height than CN.

Adult↗

PubMed1994

Antimicrobial activity of Ganoderma lucidum extract alone and in combination with some antibiotics.

Antimicrobial activity of GL (the aqueous extract from the carpophores of Ganoderma lucidum (FR)KARST) was tested in vitro against Gram positive and Gram negative bacteria by serial broth dilution method, and the antimicrobial activity was expressed by minimal inhibitory concentration (MIC). Among fifteen species of bacteria tested, the antimicrobial activity of GL was the most potent against Micrococcus luteus (MIC, 0.75 mg/ml). To investigate the effects of antimicrobial combinations of GL with four kinds of antibiotics (ampicillin, cefazolin, oxytetracycline and chloramphenicol), the fractional inhibitory concentration index (FICI) was determined by checkerboard assay for each strain. The antimicrobial combinations of GL with four antibiotics resulted in additive effect in most instances, synergism in two instances, and antagonism in two instances. Synergism was observed when GL was combined with cefazolin against Bacillus subtilis and Klebsiella oxytoca.

Anti-Bacterial Agents↗

PubMed1983

A legacy without heirs: Korean indigenous medicine and primary health care.

The ancestral shadow of Korean indigenous medicine is long, alive and kicking. The problem is what role it should have in the future of primary health care. The issue of the integration of past medical systems with the modern ones requires a closer look at theoretical as well as practical issues. In this endeavor, medical social sciences are just beginning to reconstruct models which reflect the real concerns of developing countries. These would challenge the illusion that any medical system is an ahistorical institution with autonomous ideologies or intentions. And while bio-medical interventions have significant effects on health and fertility patterns, the distribution of resources within the society and historical patterns appear to have greater persuasion. The model proposed identifies the indigenous and cosmopolitan medical systems along with the household as the main units of the 'social reproduction' of the society, or, the means by which society is renewed. In the final analysis, integration would mean that a compromised alliance had been created between all institutions involved in social reproduction--including biological reproduction, reproduction of the labour force and society's values and institutions. The key structures are the triangle-indigenous medicine, primary health care and the household. The limitations of their functions are in the modes of production from which they derive their resources, political support and even many of their values.

Community Health Services↗

PubMedDate not supplied

Quantitative analysis of HLA-B27 by flow cytometry using CD3 gating in seronegative spondylarthropathies.

OBJECTIVE: To investigate the relationship in patients with spondylarthropathies (SpA) between the clinical features of the disease and quantitative flow cytometric expression of HLA-B27 by CD3 gating. METHODS: We performed quantitative analysis of HLA-B27 antigen by flow cytometry using CD3 gating in 61 patients with seronegative and HLA-B27 positive SpA. The patients included 29 with ankylosing spondy-litis (AS), 29 with undifferentiated spondylarthropathy (uSpA), and 3 with reactive arthritis (ReA). In addition, we compared the fluorescence intensity of HLA-B27 with the clinical characteristics of the patients. RESULTS: The fluorescence intensity of HLA-B27 was significantly higher in patients with AS than in patients with other SpAs (220.5 +/- 13.7% vs 182.8 +/- 11.7%, p = 0.04). However, there were no demonstrable correlations between the quantitative expression of B27 and clinical features such as age, disease duration, results of the Schober test, chest expansion, the WBC count, erythrocyte sedimentation rate (ESR) and C-reactive protein (CRP). There was also no difference in the quantitative expression of HLA-B27 based on the presence or absence of uveitis, peripheral arthritis or enthesopathy. However, multiple regression analysis showed that age, disease duration and CRP were independent factors influencing the quantitative expression of HLA-B27 in SpA (beta = 0.568, 0.546, -0.437 and p = 0.006, 0.02, 0.04, respectively). CONCLUSIONS: Our data suggest that the quantitative expression of HLA-B27 may be related to some of the clinical features in patients with SpA.

Adolescent↗