Biomedical subjects
Publications and source records attributed to G Y Song.
Unenhanced helical computed tomography has played an increasingly important role in the management of urinary tract stones, guiding diagnosis and control of calculus disease. We report computed tomographic and radiographic appearances of a renal calculus composed of pseudoephedrine and guaifenesin in a patient who abused over-the-counter allergy medication.
Aspergillus sp. phytase contains five disulfide bonds. In order to elucidate their role, the reactivation and refolding of phytase in the absence and presence of dithiothreitol (DTT) was investigated. The results indicated that the disulfide bonds play an important role in the catalytic activity and conformational stability of the enzyme.
The presence of hypoxic cells in solid tumors has long been considered a problem in cancer treatment. Resistance of hypoxic cells to ionizing radiation and anticancer drugs has in part been attributed to changes in altered gene expression by hypoxia. We previously reported an activation of heat shock factor (Hsf) in murine tumor RIF cells following hypoxia and suggested that a subsequent accumulation of heat shock protein(s) (Hsp) is likely to contribute to the malignant progression of hypoxic tumor cells (Baek et al., 2001). In this study, we showed that hypoxia induced a DNA-binding activity of Hsf and activation of hsp70 gene expression in colon cancer Clone A cells, and that a naphthazarin derivative, S64, significantly inhibited the hypoxia-inducible hsp70 gene expression in Clone A cells. We also showed that S64 significantly reduced the cellular glutathione levels in this cell line. Considering the proposed effects of Hsp and glutathione on radiation and chemotherapy sensitivity, we suggest that the inhibitory effects of S64 on Hsf activation and cellular glutathione levels have potentially important clinical implications. We believe that the previously reported in vitro and in vivo anti-tumor effect of S64 (Song et al., 2000a, 2001) might be attributed, at least in part, to its effect on Hsf activation and/or glutathione depletion. We also believe that the detailed molecular mechanisms underlying the effects of S64 on Hsf and glutathione level following hypoxia deserve a more rigorous future study, the results of which could offer novel strategy to manipulate the resistance mechanisms of solid tumors.
Enantiomeric synthesis of D- and L-cyclopentenyl nucleosides and their antiviral activity against HIV and West Nile virus are described. The key intermediate (-)- and (+)-cyclopentenyl alcohols (7 and 15) were prepared from D-gamma-ribonolactone and D-ribose, respectively. Coupling of 7 with appropriately blocked purine and pyrimidine bases via the Mitsunobu reaction followed by deprotection afforded the target L-(+)-cyclopentenyl nucleosides (24-28, 31, 33, and 36). D-(-)-Cyclopentenyl nucleosides (1, 40, 43, and 52-56) were also prepared by a similar procedure for L-isomers from 15. The synthesized compounds were evaluated for their antiviral activity against two RNA viruses: HIV and West Nile virus. Among the synthesized D-(-)-nucleosides, adenine (1, neplanocin A), cytosine (55, CPE-C), and 5-fluorocytosine (56) analogues exhibited moderate to potent anti-HIV activity (EC(50) 0.1, 0.06, and 5.34 microM, respectively) with significant cytotoxicity in PBM, Vero, and CEM cells. Also, cytosine (55) and 5-fluorocytosine (56) analogues exhibited the most potent anti-West Nile virus activity (EC(50) 0.2-3.0 and 15-20 microM, respectively). Among L-(+)-nucleosides, only the cytosine (27) analogue exhibited weak anti-HIV activity (EC(50) 58.9 microM).
2- or 6-(1-hydroxyiminoalkyl)-5,8-dimethoxy-1, 4-naphthoquinone(2- or 6-hyim-DMNQ) derived from the roots of Lithospermum erythrorhizon was synthesized for the evaluation of antitumor activities. Among those derivatives, 2-hyim-DMNQ-S33 was found to be a potent anticancer agent. This compound suppressed the proliferation of Radiation Induced Fibrosarcoma (RIF) cells in a dose-dependent manner. 2-hyim-DMNQ-S33 significantly prolonged the survival time by 239% as compared with Sarcoma 180 tumor-bearing control mice in vivo. We found that the compound significantly suppressed phosphorylation of extracellular signal-regulated kinase (pERK) and activated c-jun-N-terminal kinase (JNK) and protein kinase C (PKC)-alpha following 4 h-treatment. These findings indicate that 2-hyim-DMSQ-S33 exerts antitumor activities by regulating pERK, JNK and PKC-alpha.
Nucleoside analogues have been the cornerstone of antiviral therapy over the past thirty years and, currently, 16 commonly used antiviral drugs belong to this category. Although for long time it was believed that only D-nucleosides, possessing a 'natural' stereochemistry, could elicit biological activity, in the last decade this has been proven not to be true. 3TC, a L-nucleoside analogue, is one of the most effective anti-HIV and anti-hepatitis B virus drugs, and nine other L-nucleosides are currently undergoing clinical trials and/or preclinical studies as antiviral or antitumoral agents. This minireview summarizes some biological features and the current status of these promising L-nucleoside analogues.
Carbocyclic 9-deazapurine nucleosides (1-4), a spiranic pyrimidone carbocyclic compound (5), and an unusual carbocyclic isonucleoside (6) were prepared as enantiomerically pure compounds via the key intermediates 10 and 21 from 1,4-gamma-ribonolactone. The key intermediate 10 was prepared by stereoselective reduction with Bu3SnH and then converted to carbocyclic C-ribonucleosides 1, 3, and 4. 2',3'-Didehydro-2',3'-dideoxycarbocyclic 9-deazainosine (2) was prepared from a 2',3'-dimesylate 17 by treatment with Li2Te followed by an acidic deprotection. The key bicyclic intermediate 21 was prepared from a diol 20 by an intramolecular cyclization using CHI3-Ph3P-imidazole and converted to the spiranic compound 5 and an olefinic nucleoside 6 by the construction of the heterocyclic moiety followed by deprotection.
Recent studies suggest that increased activation-induced lymphocyte apoptosis (AICD) is detected in mouse splenocytes during polymicrobial sepsis which may contribute to lymphocyte immune dysfunction [i.e., decreased interleukin (IL-)2 and interferon-gamma (IFN-gamma) production] leading to the associated morbidity seen in those animals. Thus, we wanted to examine the hypothesis that immune suppressive agents, such as IL-4, IL-10 or prostaglandin E2(PGE2), known to be elevated in septic animals, also contribute to this increase in AICD. Here we demonstrate that the inclusion of monoclonal antibody (mAb) to IL-10, but not anti-IL-4 or ibuprofen (IBU), blunted this sepsis induced increase in splenocyte AICD. Additionally, septic mice deficient in the IL-10 gene product (-/-) showed neither an increase in AICD nor a loss of IL-2/IFN-gamma release capacity. Interestingly, mAb to IL-10 did not altered the extent of AICD in a Th2-cell line, but exogenous IL-10 did potentiate Th1-like cell line AICD. This was consistent with the finding that the increased AICD seen in septic mouse splenocytes was restricted largely to the CD4+ cells producing IL-2 (Th1-cells) and that mAb to IL-10 treatment suppressed this change. Furthermore, IL-10 appears to mediate its AICD effect by upregulation of the Fas receptor and Fas receptor signaling protein components, but not by altered expression of Bcl/Bax/Bad family members, in septic mouse splenocytes. To the extent that these processes contribute in a pathological fashion to the animal's capacity to survive sepsis we have previously observed that in vivo post-treatment of mice with mAb IL-10 markedly attenuated septic mortality. Collectively, these data indicate that in the septic mouse the Th2 cytokine IL-10 not only serves to actively induce Th1 lymphocyte immune dysfunction but also plays a role in their apoptotic depletion. These processes in turn appear to contribute to the animal's inability to ward off lethal septic challenge.
Excessive proinflammatory cytokine and NO production by activated microglia play a role in neurodegenerative disorders. To investigate whether the neuroprotectant N-acetyl-O-methyldopamine (NAMDA) downregulates genes associated with microglial activation, we measured gene expression of TNF-alpha, IL-1beta, inducible nitric oxide synthase (NOS2), and an associated cofactor synthesis gene, GTP cyclohydrolase I (GTPCH) in LPS-stimulated microglia cells in the presence or absence of NAMDA. The temporal pattern of cytokine gene expression showed that LPS (0.2 microg/ml) increased TNF-alpha and IL-1beta gene expression at 1 and 3 h, which was repressed by cotreatment of NAMDA. Similarly, LPS also induced GTPCH and NOS2 gene expression at 3 and 6 h, and cotreatment of NAMDA repressed the induction with parallel reduction of nitrite, an oxidative metabolite of nitric oxide. Since transcription factor NF-kappaB is involved in regulating expression of these genes, the effects of NAMDA on NF-kappaB nuclear translocation and DNA binding in immunostimulated microglia were investigated. We found that neither LPS-induced NF-kappaB translocation nor DNA binding activity was affected by cotreatment with NAMDA in BV-2 microglia. On the other hand, NAMDA increased intracellular cAMP levels and potentiated LPS-induced phosphorylated cAMP-responsive element binding protein (pCREB) expression. Treatment with adenosine 3'5'-cyclic monophosphothioate, a specific inhibitor of cAMP-dependent protein kinase (PKA), reversed not only NAMDA-induced pCREB upregulation but also NAMDA-induced repression of TNF-alpha and IL-1beta gene transcription. The data demonstrate that NAMDA represses LPS-induced proinflammatory cytokines gene expression via a cAMP-dependent protein kinase pathway. Thus, repressing proinflammatory cytokines and NOS2 gene expression in activated microglia by NAMDA may provide new therapeutic strategies for ischemic cerebral disease as well as other neurodegenerative diseases.
Various analogues of 5,8-dimethoxy-1,4-naphthoquinone (DMNQ) such as 2- or 6-(1-hydroxyiminoalkyl)-DMNQs were prepared and evaluated for the antitumor action. (1-Hydroxyiminoalkyl)-DMNQ derivatives expressed greater antitumor action than (1-hydroxyalkyl)- or acyl-DMNQ derivatives. Moreover, 6-(1-hydroxyiminoalkyl)-DMNQ derivatives expressed higher antitumor action than 2-sudstituted ones, suggestive of a steric effect. Some of 6-(1-propyloxyalkyl)-DMNQ derivatives with an alkyl group of butyl to octyl moiety showed T/C values of >400%
Various analogues of 5,8-dimethoxy-1,4-naphthoquinone (DMNQ) such as 2- or 6-(1-hydroxyiminoalkyl)-DMNQs were prepared and evaluated for the antitumor action. (1-Hydroxyiminoalkyl)-DMNQ derivatives expressed greater antitumor action than (1-hydroxyalkyl)- or acyl-DMNQ derivatives. Moreover, 6-(1-hydroxyiminoalkyl)-DMNQ derivatives expressed higher antitumor action than 2-sudstituted ones, suggestive of a steric effect. Some of 6-(1-propyloxyalkyl)-DMNQ derivatives with an alkyl group of butyl to octyl moiety showed T/C values of >400%.
BACKGROUND: Fas/Fas ligand (FasL) system is one of the major pathways triggering apoptosis that has been shown to play an important role in development and pathogenesis of various diseases including liver and gastrointestinal diseases. Studies indicate that FasL deficiency provides a survival advantage in mice subjected to polymicrobial sepsis. However, the extent to which Fas/FasL contributes to organ injury during sepsis is unclear. Thus, the aim of this study was to determine whether in vivo administration of a Fas-signaling inhibitor during sepsis preserves organ function. METHODS: Male adult C3H/HeN mice were subjected to cecal ligation and puncture (CLP) or sham CLP (sham). Twelve hours after CLP, mice received either Fas-receptor fusion protein (FasFP) (200 microg/kg body weight) or the saline vehicle. Twenty-four hours after the onset of sepsis, cardiac output and organ blood flow were measured with radioactive microspheres. Plasma levels of alanine aminotransferase, aspartate aminotransferase, and lactate dehydrogenase were assessed as indexes of liver damage. Changes in systemic cytokines were measured by enzyme-linked immunosorbent assay. RESULTS. The data indicate that although cardiac output and organ blood flow in the liver, intestine, kidneys, spleen, and heart decreased markedly at 24 hours after CLP, treatment with FasFP maintained the measured hemodynamic parameters and improved hepatic, intestinal, and heart blood flow (P <.05) and partially restored spleen and renal blood flow. Moreover, FasFP treatment markedly attenuated the systemic rise in alanine aminotransferase, aspartate aminotransferase, lactate dehydrogenase, and interleukin 10 (P <.05). CONCLUSIONS: These results not only indicate that there is a role for Fas/FasL-mediated processes in the induction of organ injury but suggest that inhibition of Fas/FasL pathway may represent a novel therapeutic modality for maintaining organ perfusion and preventing liver injury during sepsis.
An asymmetric synthesis of carbocyclic orotidine 15 and its monophosphate 16 were accomplished via the key intermediate cyclopentanone 4, which was prepared from D-gamma-ribonolactone in steps. None of synthesized the compounds inhibited orotidine 5'-monophosphate decarboxylase (EC 4.1.1.23) or orotate phosphoribosyltransferase (EC 2.4.2.10).
Studies indicate that polymicrobial sepsis in humans and animals is characterized by a biphasic response, which is dominated early by proinflammation, but over time develops into a state of generalized anti-inflammation (depressed Th1 cell response and decreased macrophage (M0) capacity to release proinflammatory cytokines). However, with respect to the macrophage, it remains unknown what mechanism(s) controls this change. In this regard it is well documented that the p38 mitogen activated protein kinase pathway (MAPK) plays a central role in the regulation of Mphi functions. However, the contribution of p38 MAPK activation to the loss of these Mphi functions in polymicrobial septic animals remains unknown. To determine this we induced polymicrobial sepsis in C3H/HeN male mice using cecal ligation and puncture (CLP). Twenty-four hours post-CLP, during the late, immune-suppressed stage of sepsis, splenic and peritoneal Mphi were harvested, stimulated with lipopolysaccharide (LPS), and the activation of p38 MAPK assessed. In Mphi from CLP mice, p38 MAPK activity was markedly increased. To determine the extent that these changes in p38 MAPK had an impact on Mphi immune function, cells were pretreated with 10 microM of the p38 MAPK inhibitor, SB203580, or with DMSO vehicle, and subsequently stimulated with LPS. IL-10, IL-6, IL-12, and nitric oxide release was determined. Our results indicate that with LPS stimulation alone, there was a marked increase in the release of the anti-inflammatory mediator, IL-10 after CLP. Alternatively, proinflammatory IL-12 and IL-6 release was suppressed. Treatment with SB203580 suppressed the increase in IL-10 release seen after CLP, while partially restoring IL-12 secretion. IL-6 release was partially restored only in splenic macrophages treated with SB203580. To the extent that these in vitro findings could be translated to an in vivo setting, we assessed the in vivo effects of p38 MAPK inhibition on survival. Mice were given 100 mg of SB203580/kg body weight or saline vehicle (intraperitoneal) either immediately post-CLP or 12 h post-CLP. Delayed administration of SB203580 significantly improved survival, while also preventing the increased NO and IL-10 release and improving IL-12 release by macrophages. These results suggest that p38 MAPK pathway plays a critical role in the induction of an immune-suppressive macrophage phenotype, and that inhibition of p38 MAPK markedly improves survival following polymicrobial sepsis.
Although studies indicate that a shift from a Th1 to a Th2 response contributes to a marked suppression of cell-mediated immunity during sepsis, the mechanism by which this occurs remains unknown. Given that the mitogen-activated protein kinase (MAPK) p38 plays a critical role in the activation and function of immune cells, the aim of this study was to determine the contribution of MAPK p38 activation to the immune dysfunction seen in polymicrobial sepsis. To study this, polymicrobial sepsis was induced in C3H/HeN male mice by cecal ligation and puncture (CLP). Splenic lymphocytes and purified T cells were harvested 24 h post-CLP, pretreated with the specific MAPK p38 inhibitor SB-203580, and then stimulated with a monoclonal antibody against the T cell marker CD3. The results indicate that interleukin (IL)-2 release is markedly depressed while the release of the immunosuppressive mediator, IL-10, as well as mRNA levels of IL-10 and IL-4, are augmented after CLP. Inhibition of MAPK p38 suppressed in vitro IL-10 levels as well as IL-10 and IL-4 gene expression while restoring the release of IL-2. To determine whether these in vitro findings could be translated to an in vivo setting, mice were given 100 mg of SB-203580/kg body wt or saline vehicle (intraperitoneal) at 12 h post-CLP. Examination of ex vivo lymphocyte responsiveness indicated that, as with the in vitro finding, septic mouse Th1 responsiveness was restored. In light of our recent finding that delayed in vivo SB-203580 treatment also improved survival after CLP, we believe that these results not only illustrate the role of MAPK p38 in the induction of immunosuppressive agents in sepsis but demonstrate that SB-203580 administration after the initial proinflammatory state of sepsis significantly prevents the morbidity from sepsis.
Hepatitis B virus (HBV) is the third most common disease after venereal diseases and chickenpox. HBV currently infects 2 billion people in the world, of which 350 million are chronic carriers. At least 1 million chronically infected individuals die each year due to HBV-related diseases, especially cirrhosis and liver cancer. The greatest concern about the diffusion of this virus is in endemic regions in central and southern Africa, South-East Asia and South America, where neonatal exposure results in high mortality rates. Anti-HBV therapy has made important progresses in the last decade, with two approved drugs and a number of other potent agents in the pharmaceutical industry pipeline. Nevertheless, resistance and viral rebound are still major issues in devising a winning strategy, and there is a continuous need of developing new active compounds, as well as therapeutic protocols based on combination therapy and a prophylactic approach. This review will summarize the latest advances in anti-HBV therapy, with particular regard to the latest clinical data on the most significant anti-HBV agents. Issues such as viral resistance and combination therapy will be highlighted.
All of 13 (E)-6-(1-alkyloxyiminomethyl)-5,8-dimethoxy-1,4-naphthoquinone derivatives synthesized showed high ED50 values, ranging from 0.1 to 0.3 microg/mL against L1210 cells. However, they were inactive on A549 cells. Nine compounds exhibited higher T/C (%) values (318-388%) than Adriamycin (T/C, 315%).
BACKGROUND: Studies have indicated that a shift from a Th1 to a Th2 response occurs that contributes to the late immunosuppression seen during sepsis. However, the mechanism by which this occurs is unknown. In this regard, mediators released in response to sepsis are thought to upregulate a family of stress-induced mitogen-activated protein kinases (MAPKs), such as JNK, ERK, and p38 MAPK, which may play a role in this process. MATERIALS AND METHODS: To determine the role of MAPK in immune suppression, we induced polymicrobial sepsis in C3H/HeN male mice using cecal ligation and puncture (CLP). Splenic lymphocytes were harvested 24 h post-CLP and stimulated with the T-cell mitogen concanavalin A, and the expression and activation of these MAPKs were assessed by Western analysis. To determine the extent to which these MAPKs may have an impact on splenic immune function, cells were pretreated with a 10 microM concentration of the p38 MAPK inhibitor SB203580 or the MEK inhibitor PD98059 or with DMSO vehicle. The cells were then stimulated with 2.5 microg/ml of the T-cell mitogen concanavalin A, and cytokine release was then determined (by ELISA). RESULTS: In the lymphocytes from CLP mice no JNK signal was detected, however, p38 expression and activation were markedly (P < 0.05, n = 6) increased. In contrast, the expression of activated ERK markedly decreased following septic challenge. The results indicate that p38 MAPK inhibition with SB203580 suppressed the sepsis-induced augmentation of interleukin-10 release while restoring the suppressed Th1 cytokine interleukin-2 release typically encountered following sepsis. Inhibition of ERK had no effect on cytokine release. Neither PD98059 nor SB203580 had an effect on interferon gamma release or on proliferative capacity. CONCLUSION: This would indicate that the induction of p38 MAPK activation in splenocytes contributes to the immunosuppression seen in late sepsis.