PubMed Health⌕ Search

Biomedical subjects

S B Han

Publications and source records attributed to S B Han.

At least 37 records · Page 2Linked to original sources
PubMed2000

Radicicol suppresses expression of inducible nitric-oxide synthase by blocking p38 kinase and nuclear factor-kappaB/Rel in lipopolysaccharide-stimulated macrophages.

We show that radicicol, a fungal antibiotic, produces a marked inhibition of p38 kinase, nuclear factor-kappaB/Rel (NF-kappaB/Rel), and inducible nitric-oxide synthase (iNOS) transcription by the macrophage line RAW 264.7 in response to lipopolysaccharide (LPS). Treatment of RAW 264.7 with radicicol inhibited LPS-stimulated p38 kinase phosphorylation in a dose-related manner. iNOS transcription, which is regulated in part by the NF-kappaB/Rel family of transcription factors, has been shown to be under the control of the p38 kinase signaling cascade. Our data also show that the p38 kinase pathway is specifically involved in LPS-induced NF-kappaB/Rel activation and iNOS expression because NF-kappaB/Rel DNA binding and iNOS mRNA production in the presence of a specific inhibitor of p38 kinase, SB203580, were dramatically diminished. In contrast, PD98059, a specific inhibitor of mitogen-activated protein kinase/extracellular signal-regulated protein kinase kinase 1 had no effect on NF-kappaB/Rel activation and iNOS expression. LPS-induced loss of inhibitory proteins IkappaB-alpha and IkappaB-beta and translocation of p65, c-Rel, and p50 was inhibited by radicicol. Collectively, this series of experiments indicates that radicicol inhibits iNOS gene expression by blocking p38 kinase signaling. Due to the critical role that NO release plays in mediating inflammatory responses, the inhibitory effects of radicicol on iNOS suggest that this potent antifungal agent may represent a useful anti-inflammatory agent.

Animals↗
PubMed1999

SHC1, a high pH inducible gene required for growth at alkaline pH in Saccharomyces cerevisiae.

In this study, we carried out a large-scale transposon tagging screening to identify genes whose expression is regulated by ambient pH. Of 35,000 transformants, two strains carrying the genes whose expression is strictly dependent on pH of growth medium were identified. One of the genes with 20-fold induction by alkali pH was identified as SHC1 gene in the Yeast Genome Directory and its expression was the highest at alkaline pH and moderately induced by osmotic stress. However, the gene was expressed neither at acidic pH nor by other stress conditions. The haploid mutant with truncated shc1 gene showed growth retardation and an abnormal morphology at alkaline pH. On the other hand, the mutant strain carrying the wild-type SHC1 gene reverted to the mutant phenotype. To confirm that Shc1p is an alkali-inducible protein, a monoclonal antibody to Shc1p was produced. While a 55-kDa protein band appeared on the Western blot of cells grown at alkaline pH, Shc1p was barely detectable on the blots of cells grown in YPD. Our results indicate that yeast cells have an efficient system adapting to large variations in ambient pH and SHC1 is one of the genes required for the growth at alkaline pH.

Amino Acid Sequence↗
PubMed1999

Cytotoxicity of urushiols isolated from sap of Korean lacquer tree (Rhus vernicifera Stokes).

Cytotoxicities of four urushiols, congeners isolated from the sap of Korean lacquer tree (Rhus vernicifera Stokes), to 29 human cancer cell lines originated from 9 organs were evaluated. Their values of 50% growth inhibition were below 4 microg/ml, and showed cell line specific cytotoxicity. The present result is the first report on the cytotoxicity of urushiols suggesting that they would have an anticancer activity to human cancer cells.

Antineoplastic Agents↗
PubMed1999

The inhibitory effect of polysaccharides isolated from Phellinus linteus on tumor growth and metastasis.

It was previously reported that polysaccharides (PL) isolated from Phellinus linteus strongly stimulated cell-mediated and humoral immunity. This study was undertaken to investigate the immunochemotherapeutic activity of PL against tumor growth and metastasis. PL alone significantly prolonged the survival rate of B16F10-implanted mice, inhibited tumor growth in NCI-H23-implanted nude mice, and reduced the frequency of pulmonary metastasis of B16F10 melanoma. Adriamycin significantly inhibited tumor growth, but only slightly inhibited metastasis. The combination therapy with PL and adriamycin was more effective in inhibiting tumor growth, but not metastasis. PL did not induce direct toxicity in cancer cells, which is characteristic of immunotherapeutics. In conclusion, PL might be of use in immunochemotherapy of cancer because of its effective activities on tumor growth and metastasis through the immunopotentiation of the patients without toxicity.

Animals↗
PubMed1999

Activation of NF-kappaB/Rel in angelan-stimulated macrophages.

In our previous studies we showed that the primary target cell of angelan, a polysaccharide purified from Angelica gigas Nakai, is a macrophage (Han et al., 1998). In the present study we examined the effect of angelan on iNOS, IL-1beta, and TNF-alpha transcription in mouse macrophage line RAW 264.7. We show that angelan produces a marked induction of iNOS, IL-1beta, and TNF-alpha transcription by RAW 264.7 cells. Since these gene transcriptions have been recently shown to be under the control of NF-kappaB/Rel family of transcription factors, we assessed the effect of angelan on NF-kappaB/Rel using a electrophoretic mobility shift assay. Treatment of RAW 264.7 cells with angelan produced strong induction of NF-kappaB/Rel binding. Treatment of RAW 264.7 cells with angelan slightly induced AP-1 binding activity, whereas Oct binding was not affected by angelan. Angelan stimulated macrophages to activate NF-kappaB/Rel, whereas neither B-cells nor T-cells were affected by the angelan. In conclusion, we demonstrate that the stimulation effect of angelan on macrophage is mediated by specific activation of NF-kappaB/Rel.

Animals↗
PubMed1999

Inhibition of human tumor growth by 2'-hydroxy- and 2'-benzoyloxycinnamaldehydes.

2'-Hydroxycinnamaldehyde (HCA) was isolated from Cinnamomum cassia Blume (Lauraceae) and 2'-benzoyloxycinnamaldehyde (BCA) was prepared by the reaction of HCA and benzoyl chloride. HCA and BCA strongly inhibited in vitro growth of 29 kinds of human cancer cells and in vivo growth of SW-620 human tumor xenograft without the loss of body weight in nude mice. HCA prevented adherence of SW-620 cells to the culture surface but did not inhibit oncogenic K-Ras processing, implying its antitumor mechanisms at the cellular level.

Acrolein↗
PubMed1999

Use of a temporoparietal fascia-covered silastic implant in nose reconstruction after foreign body removal.

A total of 47 consecutive patients with paraffinoma of the nose underwent surgery for paraffinoma removal and insertion of temporoparietal fascia-covered Silastic implants between January of 1990 and June of 1996. There are several advantages to our procedure, and we obtained satisfactory outcomes with it. A bilateral alar rim incision was sufficient for our procedure. The Silastic implant could be sculptured easily, was not absorbed, and produced excellent cosmetic results. The fascia was highly bioadaptable and survived beneath the dermis through revascularization, even in the places where the paraffin material remained. The fascia reinforced the thinned skin that resulted after paraffinoma removal and, therefore, prevented exposure of the Silastic implant. The telangiectasia of paraffinoma of the nose improved in some patients after surgery.

Adult↗
PubMed1998

Synthesis and antitumor activity of 4-phenyl-1-arylsulfonyl imidazolidinones.

Novel 1-(1-benzoylindoline-5-sulfonyl)-4-phenyl-4,5-dihydroimidazolon es 3 synthesized show highly potent and broad cytotoxicities. Among them compound 3b (DW2143) exhibits much more potent cytotoxicities than doxorubicin and highly effective antitumor activities against murine (3LL, Colon 26) and human xenograft (NCI-H23, SW620) tumor models.

Animals↗
PubMed1998

Characteristic immunostimulation by angelan isolated from Angelica gigas Nakai.

The immunopharmacological characteristics of angelan, a polysaccharide purified from Angelica gigas Nakai, were investigated in relation to the specificity to immune cells. The treatment of angelan increased the expression of IL-2, IL-4, IL-6, and IFN-gamma. The expression of IL-6 and IFN-gamma was rapidly augmented but that of IL-2 responded later. In the case of IL-4, angelan stimulated at early time after exposure but down-regulated thereafter. These results suggested that macrophages and natural killer cells involved in nonspecific immunity were primarily activated and helper T cells were secondarily affected by angelan. Angelan also had lympho-proliferative potential to B cells, specifically. The specificity of angelan was also elucidated in a cell fractionation experiment. The activated B cells by angelan also increased antibody production. The direct activation of B cells, macrophages, and accessory cells and the indirect activation of helper T cells coordinately increased immune functions such as in vitro and in vivo T-dependent immunization and antibody production. The experiment of host resistance to syngeneic tumors also showed that angelan potentiated the immune functions. In conclusion, angelan, a purified polysaccharide from an oriental herbal drug, showed characteristic immunostimulation, which was different from clinically used polysaccharides such as lentinan and PSK.

Adjuvants, Immunologic↗
PubMed1998

Efficient in vitro model for immunotoxicologic assessment of mammary silicone implants.

In clinical and experimental studies, silicone gel has been assumed to cause immune alterations that may be related to macrophage activation of silicone implants. However, it has not been proven that the immunotoxicities are caused by the direct contact of macrophages and silicone gel because there has not been an adequate experimental model. In the present study, silicone gel was loaded directly onto Petri dishes and was distributed uniformly to the bottom by centrifugation. Peritoneal macrophages and splenic lymphocytes were cultured either on the silicone-coated plates or on the conventional, normal plates, and their functions were compared with each other. The experiments were repeated three times. The cytotoxic activities of peritoneal macrophages on cancer cells were markedly augmented by cultivation on silicone gel, and the primary T-dependent immunoglobulin M response in which macrophages participated as antigen presenting cells was also enhanced by incubation on silicone gel. However, macrophage-unrelated functions mediated by B and T lymphocytes were not affected by the silicone gel treatment. It was proven that the direct contact of macrophages with silicone gel was a primary cause of acute immune activation that was related to foreign body reaction. In addition, the present in vitro model exhibited similar silicone-induced immunotoxicities in previous animal and clinical studies.

Animals↗
PubMed1998

Effects of prostaglandins on ethanol damage in primary cultured rat hepatocytes.

OBJECTIVES: Several reports demonstrated that ethanol administration impairs the DNA synthesis in rat hepatocytes. Also, it has been demonstrated that prostaglandin (PG) helps prevent membrane damage by hepatotoxic chemicals. In this study, the authors examined PG's effects on the toxicity of ethanol in the primary culture of rat regenerations. METHODS: We examined two kinds of parameters, i.e., DNA synthesis and lipid peroxidation in the primary culture of rat hepatocytes. Hepatocytes were isolated by the collagenase perfusion method. The rate of DNA synthesis was determined by pulse-labelling cultured cells with [3H]-thymidine. Incorporation of (3H)-thymidine was determined by liquid scintillation spectrophotometer. DNA content was measured by the fluorescence spectrophotometer. The lipid peroxidation was assayed with spectrophotometer. RESULTS: The results were as follows: 1) PG family (PGA1, PGD2, PGE1, PGE2, PGG2a, PGI2 & Thromboxane B2) stimulated the DNA synthesis of hepatocytes (especially PGD2 and PGE1), 2) ethanol decreased DNA synthesis by clear dose-dependent manner, 3) the combined treatment of PGD2 or PGE1, prevents the decreasing of DNA synthesis, which was induced by ethanol, 4) in ethanol treatment, lipid peroxidation was decreased significantly, but PGD2, PGE1 and PGA1 were not affected, and 5) PGD2, PGE1 and PGA1 decreased lipid peroxidation with ethanol, significantly. CONCLUSIONS: From these results, we concluded that PG could be useful for the treatment of degenerative liver disease and alcohol-induced liver disease in the assumption that further studies on the action mechanisms of PG will continue.

Animals↗
PubMed1997

MDR-1 gene expression is a minor factor in determining the multidrug resistance phenotype of MCF7/ADR and KB-V1 cells.

The relevance of MDR-1 gene expression to the multidrug resistance phenotype was investigated. Drug-resistant cells, KB-V1 and MCF7/ADR, constantly expressed mRNA of the MDR-1 gene and were more resistant to vinblastine and adriamycin than drug-sensitive cells, KB-3-1 and MCF7. The drug efflux rate of KB-V1 was the same as KB-3-1 although the MDR-1 gene was expressed in only the resistant cell. The higher intracellular drug concentration of KB-3-1 than KB-V1 was due to the large drug influx. In the case of MCF7 and MCF7/ADR, the influx and efflux of the drug had nearly the same pattern and drug efflux was not affected by verapamil. The amount of ATP, cofactor of drug pumping activity of P-glycoprotein, was not changed by the resistance. These observations suggested that drug efflux mediated by MDR-1 gene expression was not a major determining factor of drug resistance in the present cell systems, and that the drug resistance could be derived from the change in drug uptake and other mechanisms.

ATP Binding Cassette Transporter, Subfamily B, Mem↗
PubMed1997

Limitation of Hu-PBL-scid mouse model in direct application to immunotoxicity assessment.

Hu-PBL-scid mice were directly introduced to the methods of immunotoxicity assessments. Human IgG and IgM was detected 1 week after transplantation. Cyclosporin A (CsA) and cyclophosphamide (CP), which were injected i.p. 4 weeks after transplantation, decreased the serum concentration of IgM after 2-4 days of treatment but not that of IgG. Lymphocyte proliferation induced by various mitogens and primary T-dependent antibody responses to sheep red blood cells could not be measured by using splenocytes of hu-PBL-scid mice. These results were correlated with the fact that human cells were not detected in the spleen, thymus, or blood of hu-PBL-scid mouse but were detected in lymph nodes of the intestine, which were observed by flow cytometric and immunohistochemical examinations. The present results suggest using hu-PBL-scid mice in routine immunotoxicity investigations: lymph nodes of intestines could be used as the lymphocyte source. In addition, the determination of serum Ig concentration might be used as a experimental item.

Animals↗
PubMed1996

Facilitation of apoptosis by autologous serum and related immunosuppression in the splenocyte culture.

The addition of adult mouse serum (MS) to the culture of mouse splenocytes resulted in an accelerated decrease of viable cell number during initial 24 h of culture as determined by the trypan blue dye exclusion test and the propidium iodide staining method. Furthermore, the extent of DNA fragmentation, the hallmark of apoptosis, determined by agarose gel electrophoresis and the amount of fragmented DNA measured by ELISA method showed that the extent of apoptosis was clearly increased in splenocytes cultured in the presence of MS. Under the scanning and transmission electron microscopic observations, the large portion of splenocytes showed morphological characteristics of apoptotic cells such as apoptotic body, condensed chromatin and shrunken appearance. With the accelerated rate of apoptosis, the immunocompetence of splenocytes such as the antibody production, natural killer cell activity, and proliferation by mitogens was strongly suppressed. When analyzed by surface immunolabelling flow cytometry, the subsets of lymphocytes (B, T, CD4+T and CD8+T cells) were affected in a global non-selective manner. As determined by ultrafiltration, the molecular weights of apoptosis-facilitating factors present in MS appeared to be greater than 10 kDa. Upon fractionation with Sephadex G-200, the apoptotic factors were separated into 2 fractions. In summary, results obtained in the present study indicate that some unidentified endogeneous macromolecules present in MS may produce the stimulatory effect on the apoptosis and cause immunosuppression of splenocytes under culture.

Animals↗
PubMed1996

Stimulation of humoral and cell mediated immunity by polysaccharide from mushroom Phellinus linteus.

Polysaccharide was purified from mycelial culture of Phellinus linteus (PL) and its effect on immunocompetence of normal splenocytes was observed. Overall in vitro immune function was enhanced by addition of PL into culture of mouse spleen lymphocyte and i.p. injection into mouse, while beta-glucans and other polysaccharides only raised the level of T lymphocyte-mediated immunity. PL stimulated immune functions of T lymphocytes, such as proliferation of T lymphocyte induced by mixed lymphocytes reaction and cytotoxicity of cytotoxic T cells responding to alloantigen. Nonspecific immune functions mediated by natural killer cells and macrophages were increased by treatment of PL in vivo and in vitro. PL also stimulated humoral immune function positively, such as T-dependent and T-independent primary antibody response, and acted as a polyclonal activator on B cell. PL exhibited a wider range of immunostimulation and antitumor activity than other polysaccharides isolated from Basidiomycetes.

Animals↗
PubMed1996

Rapid determination of in vivo and in vitro antibody responses by suspension hemolytic assay.

A suspension hemolytic (SH) assay newly modified in this laboratory was applied to the measurement of primary IgM antibody responses, such as T-dependent, T-independent, and polyclonal B cell responses in in vivo and in vitro assays. All results of the SH assay were equal to those of the conventional plaque-forming cell (PFC) assay. With the SH assay in in vitro assays, we could separately measure the amount of the IgM that had been produced during the whole immunization period and measure the IgM newly produced during the shorter time of the assay. The immunomodulations by dioxin and glycopeptide were accurately evaluated by the SH and the PFC assay. Our study suggested that the SH assay modified in this laboratory was more advantageous because of the simplicity of the assay and better analysis of data than the PFC assay, and could be used as the primary method in studying the effects of pharmaceutical and toxic agents on humoral immune functions.

Animals↗