Facile and Green Synthesis of Graphene-Based Conductive Adhesives via Liquid Exfoliation Process

In this study, we report a facile and green process to synthesize high-quality and few-layer graphene (FLG) derived from graphite via a liquid exfoliation process. The corresponding characterizations of FLG, such as scanning electron microscopy (SEM), transmission electron microscope (TEM), atomic force microscopy (AFM) and Raman spectroscopy, were carried out. The results of SEM show that the lateral size of as-synthesized FLG is 1–5 μm. The results of TEM and AFM indicate more than 80% of graphene layers is <10 layers. The most surprising thing is that D/G ratio of graphite and FLG are 0.15 and 0.19, respectively. The result of the similar D/G ratio demonstrates that little structural defects were created via the liquid exfoliation process. Electronic conductivity tests and resistance of composite film, in terms of different contents of graphite/polyvinylidene difluoride (PVDF) and FLG/PVDF, were carried out. Dramatically, the FLG/PVDF composite demonstrates superior performance compared to the graphite/PVDF composite at the same ratio. In addition, the post-sintering process plays an important role in improving electronic conductivity by 85%. The composition-optimized FLG/PVDF thin film exhibits 81.9 S·cm⁻¹. These results indicate that the developed FLG/PVDF composite adhesives could be a potential candidate for conductive adhesive applications.

Wide-range work-function tuning of active graphene transparent electrodes via hole doping

A novel strategy for preparing active transparent conductive electrodes by doping LBL-stacked graphene with AuCl₃, successfully achieving an extremely wide range of work-function tunability of up to ~1.5 eV.

Blending of polyethylenimine with a cationic polyurethane greatly enhances both DNA delivery efficacy and reduces the overall cytotoxicity

Three blending methods were introduced to combine a biodegradable cationic- polyurethane (PUg3) and polyethylenimine (PEI) together with DNA by different mixing sequences. Results of gel electrophoresis assays and particle size measurements show that complexes prepared by method 1 and 3 bear an ability to condense DNA into small nanoparticles. On the contrary, the use of method 2 in making complexes produces significantly large particles because of the weaker interaction with DNA and lack of DNA condensation. Moreover, cell proliferation assays show that no cytotoxicity of the DNA/blended-polymers complexes (exhibited by method 1) was found and due to a result of the outer coating of PUg3, reducing cytotoxic PEI exposure outside the complexes. With a new technique in pharmaceutics, the complexes prepared for DNA delivery by mixing of PEI and PUg3 with DNA in a sequence (method 1) could achieve an even better transfection efficiency (reaching 40% higher) than using PEI alone as well as reduce the cytotoxicity substantially. In conclusion, a new class of complexes (non-viral combo-system) made by a skillful blending sequence (method 1) has been designed and demonstrated to obtain the beneficial properties from two useful and individual polymers for gene delivery. This method can be used in greatly improving the transfection efficiency of polymer-based gene vectors. The blended polymers with DNA also have a better biocompatibility and no cytotoxicity, which are the requirements and critical points for great success in performing gene therapy in vivo.

Toluidine blue O photodynamic inactivation on multidrug-resistant Pseudomonas aeruginosa

BACKGROUND AND OBJECTIVES

Multidrug-resistant (MDR) Pseudomonas aeruginosa infection is becoming a critical problem worldwide. Currently, only limited therapeutic options are available for the treatment of infections caused by MDR P. aeruginosa, therefore, the development of new alternative treatments is needed. Toluidine blue O (TBO) is an effective antibacterial photosensitizing agent against various bacteria. However, reports on antibacterial photosensitization of MDR bacteria are limited. This study aims to determine the in vitro photobactericidal activity of TBO against MDR P. aeruginosa.

STUDY DESIGN/MATERIALS AND METHODS

The efficacy of antibacterial photodynamic inactivation, DNA fragmentation and protein carbonylation of three MDR P. aeruginosa strains and one susceptible strain was compared using TBO as the photosensitizer followed by red light irradiation (630 nm, 90 J/cm(2)) from a light-emitting diode light source. Subsequently, the efficacy of TBO photodynamic inactivation (TBO-PDI) on 60 MDR strains, including 11 with the efflux pump phenotype and 49 with no pump activity, was tested using the minimum lethal drug concentration (MLC) assay.

RESULTS

TBO-PDI caused similar bactericidal effect (6-7 logs of killing effect), DNA fragmentation and protein carbonylation in three MDR and one susceptible P. aeruginosa strains. Although the TBO accumulation assay indicated that TBO is a substrate for the efflux pump, TBO-PDI produce similar photobactericidal activity against 60 MDR P. aeruginosa strains, either with or without efflux-pump phenotype, and 19 susceptible strains.

CONCLUSION

MDR did not affect the susceptibility of P. aeruginosa strains to TBO-PDI. The efflux pump played an insignificant role in TBO-PDI of MDR P. aeruginosa.

Non-steroidal anti-inflammatory drugs inhibit matrix metalloproteinase-2 expression via repression of transcription in lung cancer cells

Recent studies show that up-regulation of cyclooxygenase-2 (COX-2) in human cancer cells induces activation of matrix metalloproteinases (MMPs) and increase of metastatic potential. In this study, we investigate the effect of a COX-2 selective inhibitor, NS398, on the expression and enzymatic activity of MMPs in human lung cancer cells. We found that NS398 inhibited MMP-2, not MMP-9, mRNA expression. NS398 also reduced the amount of MMP-2, not MMP-9, released into the medium. Additionally, this COX-2 inhibitor attenuated the degrading activity of MMP-2 as demonstrated by gelatin zymography. Investigation of cellular MMP-2 by Western blotting indicated that synthesis and processing of MMP-2 was significantly suppressed by NS398. We performed promoter activity assay to address whether NS398 might affect MMP-2 gene transcription. Our results indicated that NS398 directly inhibited MMP-2 promoter activity. However, the inhibitory effect of NS398 is not fully dependent on inhibition of COX-2 because a high concentration of NS398 was needed to suppress MMP-2 expression and addition of prostaglandin E2 only partially reversed the action of NS398. Moreover, a non-selective COX inhibitor indomethacin also suppressed the expression of MMP-2. Taken together, these results indicate that non-steroidal anti-inflammatory drugs suppress MMP-2 expression via repression of transcription and support the notion that COX inhibitors may be useful in inhibition and/or prevention of metastasis.

Advanced glycation end product-induced proliferation in NRK-49F cells is dependent on the JAK2/STAT5 pathway and cyclin D1

Advanced glycation end products (AGEs) are important in the pathogenesis of diabetic nephropathy, which leads to renal fibrosis. Previously, we found that the janus kinase (JAK)/signal transducers and activators of transcription (STAT) signaling pathway is necessary for AGE-induced cellular proliferation in normal rat kidney interstitial fibroblast (NRK-49F) cells. However, a direct link between JAK/STAT and cell-cycle progression has not been well established. In this regard, STAT5 has been found to induce cyclin D1 and proliferation in hematopoietic cells. Therefore, we examined effects of AGE on STAT5 and cell-cycle-dependent mitogenesis in NRK-49F cells. We found that AGE increased cyclin D1 expression and cyclin-dependent kinase (cdk)4 activity while decreasing p21(WAF1/CIP1) expression. We also found that AGE (100 microg/mL) induced STAT5 tyrosine phosphorylation. Meanwhile, AGE induced STAT5 protein-DNA binding activity, which was reversed by AG-490 (a specific JAK2 inhibitor) and STAT5 decoy oligodeoxynucleotide (ODN). In addition, STAT5 decoy ODN reversed AGE-induced cell-cycle-dependent cellular proliferation and cyclin D1 protein expression. We concluded that AGE induced cell-cycle-dependent cellular proliferation by inducing the JAK2-STAT5-cyclin D1 and cdk4 pathways in NRK-49F cells.

Role of AKT kinase in sphingosine-induced apoptosis in human hepatoma cells

Our previous work has shown that a number of sphingolipid metabolites including sphingosine, sphinganine, and other long-chain bases potently induced apoptosis in human hepatoma cells. In this study, we examined the possibility that sphingosine may trigger apoptosis in human hepatoma cells via inhibition of anti-apoptotic pathways. We investigated the effect of sphingosine on AKT kinase, a serine/threonine kinase which was found to protect cells from apoptosis induced by a variety of extracellular stresses. Our results indicated that sphingosine inhibited basal and serum-stimulated AKT kinase activity in a dose-dependent manner in hepatoma cells. Additionally, sphingosine-induced inhibition of AKT kinase was correlated with induction of apoptosis in these cells. Pretreatment of insulin, a potent stimulator of AKT kinase, partially reversed the inhibition of AKT kinase by sphingosine and counteracted the apoptotic action of this sphingolipid. Expression of activated AKT kinase partially protected cells from sphingosine-induced apoptosis, whereas expression of kinase-dead AKT kinase had no effect. The molecular mechanism by which AKT kinase suppressed the apoptotic action of sphingosine was investigated. Our results showed that increased release of cytochrome C from mitochondria and subsequent activation of caspase-3 were detected in sphingosine-treated hepatoma cells. On the contrary, expression of activated AKT kinase in Hep3B cells attenuated cytochrome C release and caspase-3 activation induced by sphingosine. Taken together, these findings suggest that suppression of AKT kinase is one of the mechanisms by which sphingosine induces apoptosis in hepatoma cells and activation of AKT kinase may inhibit sphingosine-induced apoptosis by blocking a step upstream of cytochrome C release and caspase-3 activation.

Successful metallic stent placement for recurrent stenosis after balloon angioplasty of membranous obstruction of inferior vena cava

A 23 year-old Taiwanese male presented with complete membranous obstruction of the inferior vena cava at its suprahepatic portion. After 3 angioplasty procedures using Inoue-balloon catheters, a Wall stent was deployed for restenosis 4 years after the first procedure. Venography at 6 months showed no significant restenosis. At 20 months transfemoral venography confirmed patency of the vena cava.

Role of receptor for advanced glycation end-product (RAGE) and the JAK/STAT-signaling pathway in AGE-induced collagen production in NRK-49F cells

Advanced glycation end-product (AGE) is important in the pathogenesis of diabetic nephropathy (DN), and captopril (an angiotensin converting enzyme inhibitor) is effective in treating this disorder. We have shown that the Janus kinase (JAK)/signal transducers and activators of transcription (STAT) cascade is responsible for AGE-induced mitogenesis in NRK-49F (normal rat kidney fibroblast) cells, but its role in renal fibrosis in DN remains unknown. Therefore, we have sought to determine whether JAK/STAT is involved in AGE-regulated collagen production in NRK-49F cells. We found that AGE time (1-7 days) and dose (10-200 microg/ml)-dependently increased collagen production in these cells. Additionally, AGE increased RAGE (receptor for AGE) protein expression. AGE-induced RAGE expression was dose-dependently inhibited by antisense RAGE oligodeoxynucleotide (ODN) and captopril. AGE-induced type I collagen production and JAK2-STAT1/STAT3 activation were decreased by AG-490 (a specific JAK2 inhibitor), antisense RAGE ODN and captopril. Meanwhile, STAT1 and STAT3 decoy ODNs also suppressed the induction of collagen by AGE. We concluded that RAGE and the JAK2-STAT1/STAT3 pathway were involved in AGE-induced collagen production in NRK-49F cells. Furthermore, captopril was found to reverse AGE-induced collagen production, probably by attenuating RAGE expression and JAK2-STAT1/STAT3 activities.

Role of receptor for advanced glycation end-product (RAGE) and the JAK/STAT-signaling pathway in AGE-induced collagen production in NRK-49F cells

Advanced glycation end-product (AGE) is important in the pathogenesis of diabetic nephropathy (DN), and captopril (an angiotensin converting enzyme inhibitor) is effective in treating this disorder. We have shown that the Janus kinase (JAK)/signal transducers and activators of transcription (STAT) cascade is responsible for AGE-induced mitogenesis in NRK-49F (normal rat kidney fibroblast) cells, but its role in renal fibrosis in DN remains unknown. Therefore, we have sought to determine whether JAK/STAT is involved in AGE-regulated collagen production in NRK-49F cells. We found that AGE time (1-7 days) and dose (10-200 microg/ml)-dependently increased collagen production in these cells. Additionally, AGE increased RAGE (receptor for AGE) protein expression. AGE-induced RAGE expression was dose-dependently inhibited by antisense RAGE oligodeoxynucleotide (ODN) and captopril. AGE-induced type I collagen production and JAK2-STAT1/STAT3 activation were decreased by AG-490 (a specific JAK2 inhibitor), antisense RAGE ODN and captopril. Meanwhile, STAT1 and STAT3 decoy ODNs also suppressed the induction of collagen by AGE. We concluded that RAGE and the JAK2-STAT1/STAT3 pathway were involved in AGE-induced collagen production in NRK-49F cells. Furthermore, captopril was found to reverse AGE-induced collagen production, probably by attenuating RAGE expression and JAK2-STAT1/STAT3 activities.

Induction of p27(KIP1) as a mechanism underlying NS398-induced growth inhibition in human lung cancer cells

Increased expression of cyclooxygenase-2 (COX-2) causes enhanced production of prostaglandins, which are emerging as important mediators of growth stimulation of cancer cells. Overexpression of COX-2 has been found in human non-small cell lung cancer tissues and cell lines. In vitro and in vivo studies showed that nonselective cyclooxygenase inhibitors (like aspirin and indomethacin) may suppress growth of lung cancer cells and may prevent lung tumorigenesis induced by the tobacco-specific carcinogens. However, the molecular mechanisms that mediated the anticancer action of these inhibitors are not well defined. In this study, we examined the effect of a specific COX-2 inhibitor, N-(2-cyclohexyloxy-4-nitrophenyl)methanesulfonamide (NS398), on high COX-2-expressing A549 lung cancer cells. Our results indicated that NS398 inhibited prostaglandin E(2) synthesis and induced G(1) growth arrest in these cells. NS398 specifically up-regulated cyclin-dependent kinase inhibitor p27(KIP1), whereas the expressions of G(1)-acting cyclins and cyclin-dependent kinases were not changed. Additionally, NS398 effectively suppressed cyclin E-associated kinase activity in A549 cells. The molecular mechanism responsible for the induction of p27(KIP1) by NS398 was characterized. We found that NS398 did not induce p27(KIP1) through transcriptional activation because this drug could not stimulate the p27(KIP1) promoter. Metabolic labeling experiments showed that the synthesis rate of p27(KIP1) protein was not altered by NS398. Conversely, pulse-chase assays demonstrated that degradation of p27(KIP1) protein was obviously reduced in NS398-treated cells. We conclude that NS398 enhances p27(KIP1) expression via post-translational regulation, and our results provide a new mechanism by which specific COX-2 inhibitors suppress proliferation of cancer cells.

Modulation of cell cycle regulatory protein expression and suppression of tumor growth by mimosine in nude mice

Our previous results demonstrated that the plant amino acid mimosine blocked cell cycle progression and suppressed proliferation of human lung cancer cells in vitro by multiple mechanisms. Inhibition of cyclin D1 expression or induction of cyclin-dependent kinase inhibitor p21WAF1 expression was found in mimosine-treated lung cancer cells. However, whether mimosine may modulate the expression of these cell cycle regulatory proteins and suppress tumor growth in vivo is unknown. In this study, we examined the anti-cancer effect of mimosine on human H226 lung cancer cells grown in nude mice. Our results demonstrated that mimosine inhibits cyclin D1 and induces p21WAF1 expression in vivo. Furthermore, results of TUNEL analysis indicated that mimosine may induce apoptosis to suppress tumor growth in nude mice. Collectively, these results suggest that mimosine exerts anti-cancer effect in vivo and might be useful in the therapy of lung cancer.

Induction of p21WAF1 expression via Sp1-binding sites by tamoxifen in estrogen receptor-negative lung cancer cells

Although originally synthesized as an anti-estrogen, tamoxifen (Tam) was found to be able to inhibit proliferation of estrogen receptor (ER)-negative cancer cells in vitro. However, the molecular basis of such ER-independent growth inhibition is largely unknown. We have previously demonstrated that Tam induces p21WAF1 and p27KIP1 expression in human lung cancer cells which lack ER-alpha and -beta. We found that Tam induced p21WAF1 expression via transcriptional activation. In order to determine the molecular mechanism responsible for p21WAF1 induction by Tam, we performed a deletion analysis on the p21WAF1 promoter. The minimal region in the p21WAF1 promoter required for Tam-activated induction was mapped to a contiguous stretch of 10 bp located 83 bases upstream of the transcription initiation site. Our results showed that transcription factor Sp1 and Sp3 bound to this GC-rich region and mutation of Sp1-binding sites dramatically attenuated Tam-induced p21WAF1 promoter activity. We also tried to elucidate the signaling pathway that mediated the activation of p21WAF1 by Tam. Inhibition of mitogen-activated protein kinase pathways did not block Tam-induced p21WAF1. Similarly, protein kinase C inhibitor calphostin C could not suppress Tam-induced p21WAF1. Conversely, pretreatment of a specific protein kinase A inhibitor H89 significantly attenuated the induction of p21WAF1 by Tam. Furthermore, PKA activators forskolin and dibutyryl-cAMP activated p21WAFI promoter activity and increased p21wAF1 protein level in lung cancer cells. Taken together, these results demonstrate that Tam activates the p21WAF1 promoter via Sp1-binding sites and suggest that PKA may be involved in the induction of p21wAF1 by Tam in ER-negative lung cancer cells.

Order-disorder transition in bilayers of diphytanoyl phosphatidylcholine

A comparative study on bilayers of diphytanoyl phosphatidylcholine (DPhPC) and bilayers of dimyristoyl phosphatidylcholine (DMPC) was made by X-ray lamellar diffraction as a function of temperature and the degree of hydration. An order-disorder phase transition of DPhPC reveals an interesting contrast to the standard model of DMPC. Electron density profiles allow us to deduce the conformational changes which occur in the headgroup-glycerol region and in the chain region. The important conclusion is that the lipid headgroup may have different conformational energetics in lipids of different chains. We explain why this is important to protein-membrane interactions.

The antiplatelet activity of tetramethylpyrazine is mediated through activation of NO synthase

Tetramethylpyrazine (TMPZ) is an active ingredient of a Chinese herbal medicine (Ligusticum wallichii Franchat). In this study, TMPZ (50-200 microM) significantly increased production of nitrate and cyclic GMP in human platelets within a 15-min incubation period. TMPZ concentration-dependently inhibited intracellular Ca2+ mobilization in human platelets stimulated by collagen (5 microg/ml). Furthermore, TMPZ concentration (50 and 200 microM)- and time (15 and 30 min)-dependently triggered endothelial-type constitutive nitric oxide synthase (ecNOS) protein expression in human platelets. These results indicated that TMPZ at micromolar concentrations stimulated nitric oxide production in human platelets via a novel mechanism that activated ecNOS protein expression.

Antithrombotic effect of rutaecarpine, an alkaloid isolated from Evodia rutaecarpa, on platelet plug formation in in vivo experiments

In this study, platelet thrombi formation was induced by irradiation of mesenteric venules with filtered light in mice pretreated intravenously with fluorescein sodium. Rutaecarpine (200 microg/g) significantly prolonged the latent period of inducing platelet plug formation in mesenteric venules when it was intravenously injected. Rutaecarpine (200 microg/g) prolonged occlusion time by approximately 1.5-fold (control 127 +/- 29 vs. taecarpine 188 +/- 23 s). Furthermore, aspirin (250 microg/g) also showed a similar prolongation of the occlusion time in this experiment. On a molar basis, rutaecarpine was approximately twofold more potent than aspirin at prolonging the occlusion time. Furthermore, rutaecarpine was also effective in reducing the mortality of ADP-induced acute pulmonary thromboembolism in mice when administered intravenously at doses of 25 and 50 microg/g. Intravenous injection of rutaecarpine (50 microg/g) significantly prolonged the bleeding time by approximately 1.5-fold compared with normal saline in the severed mesenteric arteries of rats. Continuous infusion of rutaecarpine (5 microg/g/min) also significantly increased the bleeding time 1. 5-fold, and the bleeding time returned to baseline within 60 min after cessation of rutaecarpine infusion. These results suggest that rutaecarpine has an effective anti-platelet effect in vivo and that it may be a potential therapeutic agent for arterial thrombosis, but it must be assessed further for toxicity.

Inhibitory effect of mimosine on proliferation of human lung cancer cells is mediated by multiple mechanisms

The plant amino acid mimosine has been reported to block cell cycle progression in the late G1 phase. A recent study showed that mimosine might induce growth arrest by activating the expression of p21CIP1, a cyclin-dependent kinase inhibitor (CDKI), and by inhibiting the activity of cyclin E-associated kinases in human breast cancer cells. However, mimosine at higher concentrations also blocked proliferation of p21-/- cells by unknown mechanisms. In this study, we investigated the effect of mimosine on the expression of cyclins and CDKIs in human lung cancer cells. We found that mimosine specifically inhibited cyclin D1 expression in H226 cells. The expression of another G1 cyclin, cyclin E, was not regulated by mimosine in all lung cancer cell lines examined. Moreover, mimosine induced p21CIP1 expression in H226 and H358 cells, while it activated p27KIP1 expression in H322 cells. However, mimosine does not affect transcription of these genes directly because significant changes in cyclin D1 or CDKI expression were observed at 12-24 h after drug addition. Our results indicate that mimosine may block cell proliferation by multiple mechanisms and this amino acid is a useful agent for the study of cell cycle control.

Role of the Janus kinase (JAK)/signal transducters and activators of transcription (STAT) cascade in advanced glycation end-product-induced cellular mitogenesis in NRK-49F cells

Advanced glycation end product (AGE) is important in the pathogenesis of diabetic nephropathy, which is characterized by cellular hypertrophy/hyperplasia leading to renal fibrosis. However, the signal transduction pathways of AGE remain poorly understood. The Janus kinase (JAK)/signal transducers and activators of transcription (STAT) pathway has been associated with cellular proliferation in some extra-renal cells. Because interstitial fibroblast proliferation might be important in renal fibrosis, we studied the role of the JAK/STAT pathway in NRK-49F (normal rat kidney fibroblast) cells cultured in AGE/BSA and non-glycated BSA. We showed that AGE dose-dependently (10-200 microgram/ml) increased cellular mitogenesis in NRK-49F cells at 5 and 7 days. However, cellular mitogenesis was unaffected by the simultaneous presence of BSA. Regarding the JAK/STAT pathway, AGE (100 microgram/ml) induced tyrosine phosphorylation of JAK2 (but not JAK1, JAK3 or TYK2) at 15-60 min; it also induced the tyrosine phosphorylation of STAT1 and STAT3 at 1-2 h and 0.5-4 h respectively. Being a transcription factor, AGE also increased the DNA-binding activities of STAT1 and STAT3 AG-490 (a specific JAK2 inhibitor) (5 microM) inhibited tyrosine phosphorylation of JAK2 and the DNA-binding activities of STAT1 and STAT3. The same results were obtained by using specific 'decoy' oligodeoxynucleotides (ODNs) that prevented STAT1 and STAT3 from binding to DNA. Meanwhile, the STAT1 or STAT3 decoy ODN and AG-490 were effective in reversing AGE-induced cellular mitogenesis. We concluded that the JAK2-STAT1/STAT3 signal transduction pathway is necessary for AGE-induced cellular mitogenesis in NRK-49F cells.

Comparison of the relative activities of alpha-tocopherol and PMC on platelet aggregation and antioxidative activity

In this study, PMC (2,2,5,7,8-pentamethyl-6-hydroxychromane), a potent antioxidant derived from alpha-tocopherol, dose-dependently inhibited agonist-induced platelet aggregation in human platelet-rich plasma. PMC is over 5-10 times more potent than alpha-tocopherol in inhibiting human platelet aggregation. Moreover, PMC (25-350 microM) dose-dependently reduced the relative fluorescence intensity of platelet membrane tagged with diphenylhexatriene (DPH). PMC is about 6-times more potent than alpha-tocopherol on this effect. Furthermore, antioxidative activity of PMC was investigated using two in vitro models. PMC inhibited non-enzymatic iron-induced lipid peroxidation in rat brain homogenates with an IC50 value of 0.21+/-0.05 microM. It was more potent than alpha-tocopherol or other classical antioxidants. PMC also scavenged the stable free radical 1,1-diphenyl-2-picrylhydrazyl (DPPH). The concentration of PMC resulting in a decrease of 0.20 in the absorbance of DPPH was about 12.1+/-3.6 microM, was comparable in potency to alpha-tocopherol, butylated hydroxytoluence and Trolox. The antiplatelet activity of PMC may possibly be due initially to an increase in fluidity of the platelet membrane followed by inhibition of platelet aggregation. Our results indicate that PMC is a potentially effective antioxidant and antiaggregating agent, and could be helpful the design of compounds with more clinical effectiveness.

Tamoxifen induces p21WAF1 and p27KIP1 expression in estrogen receptor-negative lung cancer cells

Tamoxifen (Tam), besides its action as an anti-estrogen, also inhibits cell proliferation of estrogen receptor (ER)-negative cancer cells by an unknown mechanism. In this study, we used ER-negative lung cancer cells to clarify such ER-independent inhibitory effect of Tam. We found that Tam induced G1 growth arrest in these cells. However, our results indicated that the expression of G1 cyclins (including D1, 2, 3 and E) was not regulated by Tam in these lung cancer cells. Additionally, the protein levels of G1 acting cyclin-dependent kinases (CDKs), CDK2, 4 and 6, was unaltered in Tam-treated lung cancer cells with the exception of CDK2 expression in H322 cells which was attenuated by Tam in a cell line-specific manner. We next examined the effect of Tam on the expression of cyclin-dependent kinase inhibitors (CDKIs) and our results demonstrated that the expression of p21WAF1 and p27KIP1, but not p57KIP2, was strongly activated by Tam in these cells. The amounts of p21WAF1 and p27KIP1 co-immunoprecipitated with cyclin E were obviously increased after Tam treatment and reduced activity of cyclin E-associated kinases and accumulation of hypo-phosphorylated retinoblastoma (Rb) protein were clearly detected in Tam-incubated cells. No consentaneous induction of CDKIs was found when ER-negative lung cancer cells were incubated with cytotoxic drugs, cisplatin and etoposide, this indicates that enhancement of CDKI expression is not a non-specific effect of Tam. We also found that Tam may up-regulate p21WAF1 expression via transcription activation. Considered together, these results suggest that Tam-induced growth inhibition in ER-negative lung cancer cells is associated with induction of p21WAF1 and p27KIP1.

Reduction in lipopolysaccharide-induced thrombocytopenia by triflavin in a rat model of septicemia

BACKGROUND

Thrombocytopenia frequently occurs early in the course of Gram-negative bacterial infections. Triflavin, an Arg-Gly-Asp-containing disintegrin, has been suggested to interfere with the interaction of fibrinogen with the glycoprotein IIb/IIIa complex. The present study was undertaken to determine whether triflavin could prevent thrombocytopenia in lipopolysaccharide (LPS)-treated rats.

METHODS AND RESULTS

In this study, 51Cr-labeled platelets were used to assess blood and tissue platelet accumulation after LPS challenge. The administration of LPS (4 mg/kg IV bolus) for 4 hours induced a reduction in radiolabeled platelets in blood and an obvious accumulation of platelets in liver. Triflavin (500 microg/kg) but not GRGDS (20 mg/kg) significantly prevented the alteration of radiolabeled platelet distribution in blood and liver when induced by LPS. Furthermore, triflavin but not GRGDS markedly suppressed the elevation in plasma thromboxane B2 concentration within the 4-hour period of LPS administration. In LPS-treated rats, the 5-hydroxytryptamine level was lower in the blood and higher in the liver compared with levels in normal saline-treated rats. Pretreatment with triflavin (500 microg/kg) significantly reversed the 5-hydroxytryptamine concentration in blood and liver of LPS-treated rats. In histological examinations and platelet adhesion assay, triflavin markedly inhibited the adhesion of platelets to subendothelial matrixes in vivo and in vitro.

CONCLUSIONS

The results indicate that triflavin effectively prevents thrombocytopenia, possibly through the following 2 mechanisms: (1) Triflavin markedly inhibits platelet aggregation, resulting in decreased thromboxane A2 formation. (2) It inhibits the adhesion of platelets to subendothelial matrixes, thereby leading to a reversal in the distribution of platelets in blood and liver in LPS-treated rats.

Sodium butyrate enhances STAT 1 expression in PLC/PRF/5 hepatoma cells and augments their responsiveness to interferon-alpha

Although interferon-alpha (IFN-alpha) has shown great promise in the treatment of chronic viral hepatitis, the anti-tumour effect of this agent in the therapy of liver cancer is unclear. Recent studies have demonstrated that differentiation-inducing agents could modulate the responsiveness of cancer cells to IFN-alpha by regulating the expression of signal transducers and activators of transcription (STAT) proteins, a group of transcription factors which play important roles in the IFN signalling pathway. We have reported that sodium butyrate is a potent differentiation inducer for human hepatoma cells. In this study, we investigated whether this drug could regulate the expression of STAT proteins and enhance the anti-tumour effect of IFN-alpha in hepatoma cells. We found that sodium butyrate specifically activated STAT1 gene expression and enhanced IFN-alpha-induced phosphorylation and activation of STAT1 proteins. Co-treatment with these two drugs led to G1 growth arrest, accompanied by down-regulation of cyclin D1 and up-regulation of p21WAF-1, and accumulation of hypophosphorylated retinoblastoma protein in hepatoma cells. Additionally, internucleosomal DNA fragmentation, a biological hallmark of apoptosis, was detected in hepatoma cells after continuous incubation with a combination of these two drugs for 72 h. Our results show that sodium butyrate potently enhances the anti-tumour effect of IFN-alpha in vitro and suggest that a rational combination of these two drugs may be useful for the treatment of liver cancer.

The antiplatelet activity of Escherichia coli lipopolysaccharide is mediated through a nitric oxide/cyclic GMP pathway

In this study, Escherichia coli LPS dose-dependently (100-500 microg/ml) and time-dependently (10-60 min) inhibited platelet aggregation in human and rabbit platelets stimulated by agonists. LPS also dose-dependently inhibited the intracellular Ca2+ mobilization in human platelets stimulated by collagen. In addition, LPS (200 and 500 microg/ml) significantly increased the formation of cyclic GMP but not cyclic AMP in platelets. LPS (200 microg/ml) significantly increased the production of nitrate within a 10-min incubation period. Furthermore, LPS also dose-dependently inhibited platelet aggregation induced by PDBu (30 nmol/l), a protein kinase C activator. These results indicate that the antiplatelet activity of E. coli LPS may be involved in the activation of a nitric oxide/cyclic GMP pathway in platelets, resulting in inhibition of platelet aggregation. Therefore, LPS-mediated alteration of platelet function may contribute to bleeding diathesis in septicemic and endotoxemic patients.

Activation of caspase-3-like proteases in apoptosis induced by sphingosine and other long-chain bases in Hep3B hepatoma cells

Sphingosine and other long-chain bases (including sphinganine, dimethylsphingosine and stearylamine), but not octylamine (a short-chain analogue of sphinganine), induced apoptosis in Hep3B hepatoma cells. Because both D- and L-erythrosphingosine and stearylamine exert potent apoptotic effects on Hep3B cells, it is possible that these long-chain bases may activate apoptosis by inhibiting protein kinase C (PKC) activity. However, pretreatment with the PKC activator PMA could not rescue cells from apoptosis triggered by long-chain bases. Therefore the involvement of PKC in this apoptotic process requires further characterization. We also investigated whether these long-chain bases might be metabolized into ceramide in order to elicit their apoptotic action. We found that long-chain bases acted independently of ceramide in the induction of apoptosis, since addition of fumonisin B1, a fungal agent which effectively inhibits ceramide synthesis from sphingosine, did not protect against apoptosis. Additionally, we found that sphingosine-induced apoptosis was accompanied by activation of caspases. The functional role of caspases in this apoptotic process was examined by using specific caspase inhibitors. The general caspase inhibitor benzyloxycarbonyl-Val-Ala-Asp fluoromethyl ketone, which exhibits a broad specificity for caspase-family proteases, effectively blocked sphingosine-induced apoptosis. Furthermore, our results indicate that caspase-3-like proteases, but not caspase-1, are activated during apoptosis triggered by sphingosine. Enhancement of caspase-3-like activity and cleavage of poly(ADP-ribose) polymerase, an in vivo substrate for caspase-3, was clearly demonstrated in sphingosine-treated Hep3B cells. Considered together, these results suggest that caspase-3-like proteases participate in apoptotic cell death induced by sphingosine.

Triflavin potentiates the antiplatelet activity of platelet activating factor receptor antagonist on activated neutrophil-induced platelet aggregation

In this study, specific platelet activating factor (PAF) receptor antagonist ginkgolide B (BN52021) was tested for its antiplatelet activity in zymosan activated polymorphonuclear neutrophil-induced platelet aggregation. Triflavin was also tested for its antiplatelet activity compared with PAF receptor antagonist. Triflavin, an Arg-Gly-Asp-containing disintegrin purified from venom peptide inhibited platelet aggregation by interfering with the interaction of fibrinogen with the glycoprotein IIb/IIIa complex. Furthermore, we also report an efficient high resolution method for quantitative analysis of PAF using high-performance capillary electrophoresis (HPCE). The supernatant of polymorphonuclear neutrophils after their activation by opsonized zymosan induces the aggregation of washed rabbit platelets. In rabbit platelets, BN52021 (100-1000 microM) only partially inhibited activated polymorphonuclear neutrophil-induced platelet aggregation, and its maximal inhibition was estimated to be about 79%. Triflavin also partially inhibited platelet aggregation about 82% induced by activated polymorphonuclear neutrophils. Furthermore, after treatment with a combination of triflavin (0.26 microM) with various concentrations of BN52021 (4-1000 microM), the inhibitory effect of platelet aggregation was almost completely. This inhibition was greater than that produced by the individual drugs alone. These results indicate that a combination of glycoprotein IIb/IIIa complex and PAF receptor antagonist could completely inhibit activated polymorphonuclear neutrophil-induced platelet aggregation. In addition, the amount of PAF released from zymosan (6 mg/ml)-activated polymorphonuclear neutrophils was accurately calculated about 11.8+/-1.5 ng/10(6) cells, and did not further increase even at a high concentration of zymosan (10 mg/ml). These results suggest that PAF play a major role in the interaction between platelets and polymorphonuclear neutrophils. This interaction may be important in the pathogenesis of thrombosis and inflammatory diseases. Our present findings support the hypothesis that combination therapy with glycoprotein IIb/IIIa complex antagonists and PAF receptor antagonists may represent a new approach to the treatment of ischemic disorders.

The antiplatelet activity of rutaecarpine, an alkaloid isolated from Evodia rutaecarpa, is mediated through inhibition of phospholipase C

In this study, the mechanism involved in the antiplatelet activity of rutaecarpine in human platelet suspensions was investigated. In platelet suspensions (4.5 x 10(8)/ml), rutaecarpine (100 and 200 microM) did not influence the binding of FITC-triflavin to platelet glycoprotein IIb/IIIa complex. Additionally, rutaecarpine (200 microM) did not significantly change the fluorescence of platelet membrane labeled with diphenylhexatriene (DPH). On the other hand, rutaecarpine (50 and 100 microM) dose-dependently inhibited the increase in intracellular free Ca2+ of Fura 2-AM loaded platelets stimulated by collagen. Moreover, rutaecarpine (100 and 200 microM) did not significantly affect the thromboxane synthetase activity of aspirin-treated platelet microsomes. Furthermore, retaecarpine (100 and 200 microM) significantly inhibited [3H]arachidonic acid released in collagen-activated platelets but not in unactivated-platelets. Nitric oxide (NO) production in human platelets was measured by a chemiluminesence detection method in this study. Rutaecarpine (100 and 200 microM) did not significantly affect nitrate production in collagen (10 microg/ml)-induced human platelet aggregation. On the other hand, various concentrations of rutaecarpine (50, 100, and 200 microM) dose-dependently inhibited [3H]inositol monophosphate formation stimulated by collagen (10 microg/ml) in [3H]myoinositol-loaded platelets at different incubation times (1, 2, 3, and 5 minutes). It is concluded that the antiplatelet activity of rutaecarpine may possibly be due to the inhibition of phospholipase C activity, leading to reduce phosphoinositide breakdown, followed by the inhibition of thromboxane A2 formation, and then inhibition of [Ca2+]i mobilization of platelet aggregation stimulated by agonists.

Mechanisms involved in the antiplatelet activity of Escherichia coli lipopolysaccharide in human platelets

In this study, Escherichia coli lipopolysaccharide (LPS) dose-dependently (100-300 microg/ml) and time-dependently (10-60 min) inhibited platelet aggregation in human platelets stimulated by agonists. LPS also dose-dependently inhibited the phosphoinositide breakdown and the intracellular Ca+2 mobilization in human platelets stimulated by collagen. LPS (300 microg/ml) also significantly inhibited the thromboxane A2 formation stimulated by collagen in human platelets. Moreover, LPS (100-300 microg/ml) dose-dependently decreased the fluorescence of platelet membranes tagged with diphenylhexatrience. In addition, LPS (200 and 300 microg/ml) significantly increased the formation of cyclic GMP but not cyclic AMP in platelets. LPS (200 microg/ml) also significantly increased the production of nitrate within a 30 min incubation period. Rapid phosphorylation of a platelet protein of Mr 47,000, a marker of protein kinase C activation, was triggered by phorbol-12-13-dibutyrate (PDBu, 50 nM). This phosphorylation was markedly inhibited by LPS (200 microg/ml) within a 30 min incubation period. These results indicate that the antiplatelet activity of LPS may be involved in two important pathways. (1) LPS may induce conformational changes in the platelet membrane, leading to change in the activity of phospholipase C. (2) LPS also activated the formation of nitric oxide (NO)/cyclic GMP in human platelets, resulting in inhibition of platelet aggregation. Therefore, LPS-mediated alteration of platelet function may contribute to bleeding diathesis in septicaemic and endotoxaemic patients.

Transforming growth factor beta 1 potently activates CPP32-like proteases in human hepatoma cells

Induction of apoptosis in Hep3B hepatoma cells by transforming growth factor beta 1 (TGF-beta 1) was accompanied by the activation of interleukin-1-beta-converting-enzyme-like proteases, which have recently been renamed as caspases. The caspase inhibitor ZVAD-FMK, which has a broader specificity for caspase family proteases, blocked TGF-beta 1-induced apoptosis in a concentration-dependent manner. The caspases in this apoptotic process were further characterized by using a more specific caspase inhibitor, DEVD-FMK, for CPP32-like (caspase-3-like) proteases. Our results demonstrated that CPP32-like proteases were activated during apoptosis triggered by TGF-beta 1. Enhancement of CPP32-like activity was clearly detected in TGF-beta 1-treated Hep3B cells. Furthermore, cleavage of poly(ADP-ribose) polymerase, an in vivo substrate for CPP32, in these cells was confirmed by immunoblotting. Thus, we suggest that CPP32-like proteases participate in apoptotic cell death induced by TGF-beta 1.

Involvement of caspase family proteases in FPT inhibitor III-induced apoptosis in human ovarian cancer cells

We have previously demonstrated that a new farnesyltransferase inhibitor, FPT inhibitor III, triggers apoptosis in human ovarian cancer cells. Here, we report that induction of apoptotic cell death in PA-1 ovarian cancer cells by FPT inhibitor III was accompanied by the activation of interleukin-1 #-converting enzyme (ICE)-like proteases, which have recently been renamed as caspases. The caspase inhibitor, ZVAD-FMK, which inhibits a number of caspase family proteases, blocked FPT inhibitor III-induced apoptotic cell death in a dose-dependent manner. Additionally, cleavage of poly(ADP-ribose) polymerase, an identified in vivo substrate for caspase family proteases, in FPT inhibitor III-treated cells was confirmed by immunoblotting. Our results suggest that the caspase family proteases are involved in the induction of apoptosis triggered by FPT inhibitor III.

Photoionization studies of sulfur radicals and products of their reactions

A discharge flow-photoionization mass spectrometric system coupled to a synchrotron is employed to study intermediates and products of sulfur radical reactions related to atmospheric chemistry. Sulfur radicals are generated from reactions of oxygen or chlorine atoms with sulfur compounds in a flow tube. The gaseous reaction products are sampled into the ionization region via a three-stage differential pumping scheme. Photoionization spectra and ionization energies are measured by dispersing synchrotron radiation to ionize the samples. Using this technique, photoionization spectra and ionization energies of HSO, CH(3)SO, C(2)H(5)SO, HSCl, and some secondary reaction products, SSCl, HSSCl, HSSSH, CH(3)SOH and CH(3)SS(O)CH(3), were measured for the first time.

Interaction between high glucose and TGF-beta in cell cycle protein regulations in MDCK cells

Transforming growth factor-beta (TGF-beta) may mediate high glucose effects in renal cells. Thus, Madin-Darby canine kidney cells were studied for the modulation of cell cycle regulatory proteins by high glucose (27.5 mM) and TGF-beta1. We showed that unlike other renal cells, TGF-beta1 mRNA and its bioactivity were not induced by high-glucose culture. Furthermore, high glucose per se increased cellular proliferation without alterations in cell size. High glucose also increased the percentage of cells in the G2/M phase while decreasing cells in the G0/G1 phase of the cell cycle. In contrast, TGF-beta1 dose dependently (1 to 4 ng/ml) decreased cellular mitogenesis while increasing hypertrophy in the cells, especially in the presence of high glucose. TGF-beta1 also increased the percentage of cells arrested in the G0/G1 phase while decreasing cells in the G2/M phase of the cell cycle. Regarding two of the cell cycle regulatory proteins, high glucose increased cdc2 kinase activity and retinoblastoma protein (pRb) phosphorylation. In contrast, TGF-beta1 decreased cdc2 kinase activity and pRb phosphorylation, especially in the presence of high glucose. Additionally, glucose dose dependently (5.5, 16.5, 27.5, and 38.5 mM) increased type I and II TGF-beta receptor protein expression. In conclusion, changes in cdc2 kinase activity and pRb phosphorylation were correlated with high glucose and TGF-beta1-induced growth effects in a cell cycle-dependent manner in the Madin-Darby canine kidney cells. Furthermore, high glucose may potentiate TGF-beta1-induced effects by enhancing TGF-beta receptor protein expression.

The farnesyltransferase inhibitor, FPT inhibitor III upregulates Bax and Bcl-xs expression and induces apoptosis in human ovarian cancer cells

Deregulation in the ras oncogene is a common event in many types of human cancer. Our previous study clearly demonstrated that genetic alterations of ras oncogene are frequently found in human epithelial ovarian cancer. Recent reports have indicated that farnesyltransferase is involved in the regulation of post-translational modification and biological function of Ras proteins. Here, we report that a newly synthesized farnesyltransferase inhibitor, FPT inhibitor III, upregulates Bax and Bcl-xs expression and induces apoptosis in human ovarian cancer cells. This is a critical finding that farnesyltransferase inhibitors may directly activate apoptotic signaling pathways in cancer cells and may help to provide a new strategy in the treatment of human cancer.

Triflavin inhibits platelet-induced vasoconstriction in de-endothelialized aorta

Triflavin, a 7.5-kD cysteine-rich polypeptide purified from Trimeresurus favoviridis snake venom, belongs to a family of Arg-Gly-Asp-(RGD)-containing peptides, termed disintegrins. In this study, aggregating human platelets dose-dependently induced vasoconstriction in de-endothelialized isolated rat thoracic aortas. At 5x10(7) cells per milliliter, platelets induced a peak tension averaging 65 +/- 7.2% of the tension induced by phenylephrine (10 mumol/L). The relative effectiveness of RGD-containing peptides (including venom peptides triflavin and trigramin, small RGD synthetic peptides Gly-Arg-Gly-Asp-Ser [GRGDS], Gly-Arg-Gly-Asp-Phe [GRGDF], and Gly-Arg-Gly-Asp-Ser-Pro-Lys [GRGDSPK]) was examined by testing the inhibitory effect on aggregating platelet-induced vasoconstriction in de-endothelialized aorta. Triflavin (1 mumol/L) significantly inhibited the platelet-induced vasoconstriction, whereas neither trigramin (10 mumol/L) nor small RGD peptides (2 mmol/L) (i.e., GRGDS, GRGDF, and GRGDSPK) showed any significant effect. The release of serotonin and the formation of thromboxane A2 from aggregating platelets were both significantly inhibited by triflavin (2 mumol/L), whereas trigramin and small RGD-containing peptides showed no significant effect. On scanning electron micrographs of de-endothelialized aorta, aggregating platelets adhered to the subendothelium, with loss of their discoid shape, to form irregular spheres with pseudopod extensions. Triflavin (2 mumol/L) markedly reduced the adhesion of platelets to the subendothelium in the same aorta. Furthermore, RGD-containing peptides (including triflavin, trigramin, and small RGD-containing peptides) inhibited the adhesion of 10 micrograms/mL collagen-activated platelets to extracellular matrices (i.e., fibronectin, vitronectin, and von Willebrand factor). It is concluded that the marked ability of triflavin to inhibit aggregating platelet-induced vasoconstriction in de-endothelialized aorta compared with other RGD-containing peptides (including trigramin), may be due at least partly to triflavin's efficiently preventing the activation of platelets subsequent to inhibition of serotonin release and thromboxane A2 formation. However, the different abilities of triflavin compared with other RGD-containing peptides was not related to the ability to inhibit adhesion of platelets to extracellular matrices. Therefore, from the results of this study, it appears that triflavin may be a useful therapeutic agent for the treatment of thromboembolism and its associated angiospasm.

Mechanisms involved in the antiplatelet activity of tetramethylpyrazine in human platelets

Tetramethylpyrazine is the active ingredient of a Chinese herbal medicine. In this study, tetramethylpyrazine was tested for its antiplatelet activities in human platelet suspensions. In human platelets, tetramethylpyrazine (0.5-1.5 mM) dose-dependently inhibited both platelet aggregation and ATP-release reaction induced by a variety of agonists (i.e., ADP, collagen, and U46619). Tetramethylpyrazine (0.5 mM) did not significantly change the fluorescence of platelet membranes labeled with diphenylhexatriene, even at the high concentration (1.5 mM). Furthermore, tetramethylpyrazine (0.5-1.5 mM) dose-dependently inhibited [3H]inositol monophosphate formation stimulated by collagen (5 microg/ml) in [3H]myoinositol loaded platelets. Tetramethylpyrazine (0.5-1.5 mM) also dose-dependently inhibited the intracellular free Ca2+ rise of Fura 2-AM loaded platelets stimulated by collagen (5 microg/ml). Moreover, tetramethylpyrazine (0.5-1.5 mM) inhibited thromboxane B2 formation stimulated by collagen. At a higher concentration (1.0 mM), tetramethylpyrazine has also been shown to influence the binding of FITC-triflavin to platelet glycoprotein IIb/IIIa complex. Triflavin, a specific glycoprotein IIb/IIIa complex antagonist purified from Trimeresurus flavoviridis venom. It is concluded that the antiplatelet activity of tetramethylpyrazine may possibly involve two pathways: 1) at a lower concentration (0.5 mM), tetramethylpyrazine is shown to inhibit phosphoinositide breakdown and thromboxane A2 formation; and 2) at a higher concentration (1.0 mM), it leads to the inhibition of platelet aggregation through binding to the glycoprotein IIb/IIIa complex.

Inhibition of angiogenesis in vitro and in vivo: comparison of the relative activities of triflavin, an Arg-Gly-Asp-containing peptide and anti-alpha(v)beta3 integrin monoclonal antibody

Disintegrin which contains the amino acid sequence Arg-Gly-Asp (RGD), has been implicated as a recognition site in interactions between extracellular matrix (ECM) and cell membrane receptors. Triflavin, a 7.5 kDa cysteine-rich polypeptide purified from Trimeresurus flavoviridis snake venom, belongs to a family of disintegrins. Integrin alpha(v)beta3 has recently been identified as a marker of angiogenic blood vessels and therefore anti-alpha(v)beta3 mAb may significantly inhibit angiogenesis. Therefore, this study was designed to compare the relative activity of triflavin and anti-alpha(v)beta3 mAb in human umbilical vein endothelial cell (HUVEC) adhesion and migration in vitro, and on angiogenesis induced by TNF(alpha) in chicken chorioallantoic membrane (CAM). In this study, it was shown that triflavin (0.1 to 0.4 microM) dose-dependently inhibited the adhesion of HUVECs to ECMs (i.e., vitronectin, fibronectin, laminin and collagen type IV). At a concentration of 10 microM, anti-alpha(v)beta3 mAb almost completely inhibited the adhesion of cells to vitronectin, had a moderate inhibitory effect on fibronectin and laminin, but only a slight inhibitory effect on collagen type IV. On the other hand, vitronectin and fibronectin promote a significantly greater extent of cell adhesion and migration than laminin or collagen type IV over a wide range of concentrations (5 to 15 microg/ml). In cell migration studies, triflavin (0.4 microM) inhibited more markedly vitronectin- and fibronectin-mediated migration than that mediated by laminin- and collagen type IV. Comparison of the relative effectiveness of triflavin with anti-alpha(v)beta3 mAb, showed that triflavin was at least twenty to thirty times more potent than anti-alpha(v)beta3 mAb at inhibiting cell adhesion and migration. Furthermore, we used TNF(alpha) as an inducer of angiogenesis in the CAM assay. Close examination of the effects of triflavin and anti-alpha(v)beta3 mAb on TNF(alpha)-induced angiogenesis revealed the presence of discontinuous and disrupted blood vessels. However, anti-alpha(v)beta3 mAb showed a significant effect only at a higher concentration (10 microM). These results suggest that the inhibition of angiogenesis may have been due to interference with the adhesion and migration of endothelial cells to ECMs. The results also indicate that triflavin has a more powerful inhibitory effect than anti-alpha(v)beta3 mAb on angiogenesis, suggesting that triflavin could theoretically be used as a reasonable therapeutic adjuvant for therapy or prevention of angiogenesis-induced diseases.

Mechanism involved in the antiplatelet activity of naloxone in human platelets

In this study, naloxone was tested for its antiplatelet activity in human platelet suspensions. In platelet suspensions (4.5 x 10(8)/ml), naloxone (0.1-0.5 mM) significantly inhibited platelet aggregation and ATP-release stimulated by various agonists (i.e., thrombin, collagen, U46619, and ADP). Furthermore, naloxone (0.5 and 0.8 mM) dose-dependently inhibited the intracellular free Ca2+ rise of Fura 2-AM loaded platelets stimulated by collagen. Additionally, naloxone (0.5 and 1.0 mM) did not influence the binding of FITC-triflavin to platelet glycoprotein (GP) IIb/IIIa complex. On the other hand, naloxone (0.5 mM) markedly decreased the fluorescence of platelet membranes tagged with diphenylhexatriene (DPH). In addition, naloxone (0.1-0.5 mM) did not significantly affect cyclic-AMP levels in human washed platelets. It is concluded that the antiplatelet activity of naloxone may possibly be due to the induction of conformational changes in the platelet membrane and the inhibition of the intracellular Ca2+ ([Ca2+]i) mobilization as well as the release reaction of platelets stimulated by agonists.

Interaction of thrombin-activated platelets with extracellular matrices (fibronectin and vitronectin): comparison of the activity of Arg-Gly-Asp-containing venom peptides and monoclonal antibodies against glycoprotein IIb/IIIa complex

Platelets adhere to fibronectin and vitronectin substrates following activation with physiological concentrations of thrombin. Adhesion of activated-platelets to either substrate is dependent upon the amount of fibronectin and vitronectin, and the duration of the adhesion assay. In this study, we showed that the Arg-Gly-Asp-containing peptides (including naturally occurring polypeptides, triflavin, trigramin and rhodostomin, synthetic peptides GRGDS, GRGDSPK, GRGDF, and GRGD and monoclonal antibodies, 7E3, 10E5 and AP2, raised against glycoprotein IIb/IIIa complex, inhibited the adhesion of activated-platelets to fibronectin and vitronectin-coated plates in a dose-dependent manner. In fibronectin-coated plates, GRGDF was shown to be much more efficient than GRGDS, GRGDSPK and GRGD at inhibiting the adhesion of activated-platelets to immobilized fibronectin. On the other hand, there were no marked differences in the abilities of these three peptides (GRGDF, GRGDS and GRGDSPK) to inhibit platelet adhesion to immobilized vitronectin. Furthermore, the RGD-containing venom peptide, triflavin was more effective than rhodostomin and trigramin at inhibiting the adhesion of activated-platelets to either substrates. The monoclonal antibodies raised against glycoprotein IIb/IIIa complex (i.e., 7E3, 10E5 and AP2) inhibited platelet adhesion to fibronectin and vitronectin in a similar dose-dependent manner. Interestingly, we found that 7E3 was more efficient than 10E5 and AP2 in this reaction. These studies suggest that the glycoprotein IIb/IIIa complex, present on activated-platelets, may interact with fibronectin and vitronectin substrates through the Arg-Gly-Asp-dependent mechanism. Since fibronectin and vitronectin are present in the subendothelial matrix, they may be involved in platelet-vessel wall interaction. The Arg-Gly-Asp containing peptide, especially triflavin, is an ideal therapeutic agent for inhibiting thrombus formation by interrupting platelet-platelet and platelet-subendothelium interactions.

Mechanism of inhibition of platelet aggregation by rutaecarpine, an alkaloid isolated from Evodia rutaecarpa

In this study, rutaecarpine was tested for its antiplatelet activities in human platelet-rich plasma. In human platelet-rich plasma, rutaecarpine (40-200 microM) inhibited aggregation stimulated by a variety of agonists (i.e., collagen, ADP, adrenaline and arachidonic acid). The antiplatelet activity of rutaecarpine (120 microM) was not significantly attenuated by pretreatment with the nitric oxide synthase inhibitor N(G)-mono-methyl-L-arginine (L-NMMA) (100 microM) or N(G)-nitro-L-arginine methyl ester (L-NAME) (200 microM) and with the guanylyl cyclase inhibitor methylene blue (100 microM). In addition, rutaecarpine (40-200 microM) did not significantly affect cyclic AMP and cyclic GMP levels in human washed platelets, whereas it significantly inhibited thromboxane B2 formation stimulated by collagen (10 microg/ml) and thrombin (0.1 U/ml). Furthermore, rutaecarpine (40-200 microM) inhibited [3H]inositol monophosphate formation stimulated by collagen and thrombin in [3H]myoinositol-loaded platelets. It is concluded that the antiplatelet effects of rutaecarpine are due to inhibition of thromboxane formation and phosphoinositide breakdown.

Induction of apoptosis by sphingosine-1-phosphate in human hepatoma cells is associated with enhanced expression of bax gene product

Sphingolipid metabolites are important regulators of cell growth and differentiation. Recent studies have suggested that sphingosine-1-phosphate, a biologically active sphingolipid metabolite, acts as a crucial messenger in apoptosis. In the present work, we examined the expression levels of the members of the bcl-2-related gene family to determine their roles in sphingosine-1-phosphate-induced apoptosis is human hepatoma cells. Our results indicate that sphinogosine-1-phosphate-induced apoptosis is associated with enhanced expression of Bax protein. Moreover, the regulation of bax gene expression by sphingosine-1-phosphate is independent of the p53 tumor suppressor.

Expression of cyclin D1 and c-Ki-ras gene product in human epithelial ovarian tumors

The expression of cyclin D1 gene product in human ovarian tumors was studied. We found that cyclin D1 is expressed at high levels in several ovarian cancer cell lines. Immunohistochemical study also showed that a significant proportion of primary ovarian tumor tissues overexpressed cyclin D1 gene product. Clear nuclear staining of cyclin D1 protein was detected in 28% of the cases. We also characterized the expression of c-Ki-ras gene product in ovarian cancer cell lines and tumor tissues. Amplification or overexpression of this proto-oncogene has been reported in ovarian tumors from Taiwan. These results show that c-Ki-ras is strongly expressed in PA-1 and NIH:OVCAR-3 cells in which cyclin D1 also expressed at high levels. Specific cytoplasmic staining of c-Ki-ras protein was detected in 11 tumors (52%). Statistical analyses show a strong positive correlation between cyclin D1 and c-Ki-ras immunoexpression. Thus, these data support the ideas that cyclin D1 may be involved in the pathogenesis of ovarian cancer, and coactivation of cyclin D1 and c-Ki-ras gene expression may represent one of the major pathways that lead to the development of ovarian cancer in Taiwan.

Antisense oligodeoxynucleotides targeted against different regions of cyclin D1 mRNA may exert different inhibitory effects on cell growth and gene expression

The alteration of cyclin D1 gene expression is a common feature of malignancies of diverse histogenesis. Our recent results showed that over expression of cyclin D1 protein is frequently found in human ovarian cancer. In this study, we investigated the effect of cyclin D1 antisense oligodeoxynucleotides on cell growth and gene expression in PA-1 ovarian cancer cells. Our results demonstrated that cyclin D1 antisense oligodeoxynucleotides indeed functioned as an antiproliferative agent. More strikingly, we found that different cyclin D1 antisense oligodeoxynucleotides exert different efficacy on the inhibition of cell growth and gene expression. We suggest that selection and characterization of high affinity oligodeoxynucleotides is strictly required before the application of antisense technology.

Urinary epidermal growth factor receptor-binding growth factors in patients with cancers of the digestive tract

To investigate whether the urinary excretion of epidermal growth factor (EGF) and transforming growth factor-alpha (TGF-alpha) is increased in patients with cancer of the digestive tract, EGF and TGF-alpha were determined in 109 cancer patients and 40 healthy controls. Excluding EGF in hepatocellular carcinoma (HCC) and TGF-alpha in pancreatic cancer, both growth factors in each cancer group were significantly higher than in the control group. A receiver operating characteristic curve and likelihood ratio were applied to obtain the best diagnostic efficiency. Both EGF and TGF-alpha had high specificity (100%) in all cancer group. The high sensitivity of EGF in gastric cancer (100%) and metastatic liver cancer (93.3%), moderate sensitivity of TGF-alpha in metastatic liver cancer (86.6%), colon cancer (80.0%), and HCC (61.7%) suggested that they might be helpful in identifying these cancers. In conclusion, urinary excretion of EGF and TGF-alpha increased in most cancers of the digestive tract. They may be used as tumor markers.

Characterization of apoptosis induced by transforming growth factor beta 1 in human hepatoma cells

Apoptotic cell death plays a major role in the regulation of cell growth and this process may be activated by different agents through various pathways. The present study aimed to elucidated the mechanism of apoptosis caused by transforming growth factor beta 1 (TGF-beta 1) in human hepatoma cells. Several biological parameters which were reported to be crucial in the induction of programmed cell death in other experimental systems were measured. We found that TGF-beta 1-induced cell death is independent of cytosolic calcium and protein kinase C. Insulin and tumor promotor can rescue hepatoma cells from apoptosis, but the effect is time-dependent. Our results highlight that different apoptotic signal transduction pathways exist in different cell types. Apoptosis induced by TGF-beta 1 provides a good model for the understanding of cell death and the development of new anti-cancer drugs. Apoptotic cell death (apoptosis or programmed cell death) in normal tissue is a biological phenomenon that maintains hemostasis of systems of the body under physiological conditions. The features of apoptosis include condensation of chromatin, blebbing of the cell surface, transient increase in buoyant density and fragmentation of chromatin by a specific endonuclease.

Effects of insulin on TGF-beta 1-induced cell growth inhibition in the human hepatoma cell lines

The effects of insulin on cell growth control by transforming growth factor beta 1 (TGF-beta 1) in human hepatoma cell lines were studied. TGF-beta 1 inhibited cell growth and DNA synthesis of Hep3B cells but not that of HA22T/VGH cells. The cell cycle-dependent p34cdc2 kinase activity was inhibited by TGF-beta 1 in a dose-dependent manner in Hep3B cells. In contrast, the p34cdc2 kinase activity of HA22T/VGH cells was not regulated by TGF-beta 1. When insulin (10(-7) M) was added simultaneously with TGF-beta 1, we found that the inhibitory effects of TGF-beta 1 on cell growth and DNA synthesis in Hep3B cells was completely blocked and the p34cdc2 kinase activity of Hep3B cells was recovered after insulin administration. Thus, cell growth inhibition by TGF-beta 1 in Hep3B hepatoma cells can be antagonized by insulin and their interaction may play an important role in the tumor progression stage of hepatocarcinogenesis.

Effects of epidermal growth factor on growth control and signal transduction pathways in different human hepatoma cell lines

The roles of epidermal growth factor (EGF) on cell growth control and phosphatidylinositol signal transduction pathway in human hepatoma cell lines with different differentiated states were evaluated. Ligand binding study showed that only one receptor type with similar affinity was found in all three cell lines. Under serum-free conditions, EGF (10(-8)-10(-11) M) enhanced DNA synthesis and cell proliferation of the three cell lines in a dose-dependent manner. The response of the poorly differentiated HA22T/VGH hepatoma cells was most obvious whereas much smaller effects were found in Hep3B and Chang liver cells. The metabolism of phosphoinositides also increased in HA22T/VGH cells as compared with both Hep3B and Chang liver cells under basal and EGF-treated conditions. Our data indicated that EGF had different effects on different human hepatoma cell lines and its role might be more important in poorly differentiated hepatoma cells than in well differentiated ones.

Differential distribution of muscarinic receptor subtypes and their regulation by G-protein in rat brain

1. [3H]quinuclidinyl benzilate ([3H]QNB) binding in rat cerebral and cerebellar synaptosomes had different Bmax values, but similar Kd values. 2. These bindings could be displaced by classic muscarinic agents: pilocarpine (partial agonist), and atropine (antagonist), which both had similar binding affinities in rat cerebral and cerebellar synaptosomes. 3. The new muscarinic M1 selective agents: McN-A-343 (agonist), pirenzepine and trihexyphenidyl (antagonists) and higher affinities for receptor sites in the cerebrum than in the cerebellum. 4. The muscarinic M2 selective agents: carbachol, oxotremorine (agonists), and AF-DX-116 (antagonist) had higher affinities for receptor sites in the cerebellum than in the cerebrum. 5. GPP(NH)p (40 microM) decreased the binding affinities of carbachol and oxotremorine in the cerebellum, but not in the cerebrum. However, it did not decrease the binding affinities of all the antagonists studied in both brain regions. 6. These results reveal that more muscarinic M1 sites are present in the cerebrum than in the cerebellum, while the opposite is true for M2 sites. Furthermore, the regulatory role of G-protein on these muscarinic receptor subtypes in the brain is different.

Guanine nucleotides have a direct inhibitory effect on polyphosphoinositide turnover in rat cortical synaptosomes

1. The possible involvement of guanosine 5'-triphosphate (GTP)-binding proteins in the receptor mediated polyphosphoinositide (PPI) turnover event was investigated in rat cortical synaptosomes. 2. It was studied under the effects of guanine nucleotides on 32Pi incorporation into synaptosomal phospholipids in the absence or presence of carbachol. 3. The basal 32Pi incorporation into these phospholipids was altered by the presence of 1 mM carbachol: i.e. a decrease in 32Pi incorporation into phosphatidylinositol-4,5-bisphosphate and phosphatidylinositol-4-phosphate and an increase in the incorporation of 32Pi into phosphatidylinositol and phosphatidic acid. 4. In the presence of guanine nucleotides: GTP, Gpp(NH)p and GDP at suitable concentrations, there was a general decreasing effect on 32Pi incorporation into all 4 phospholipids, which are all involved in PPI turnover cycle, either in the basal or carbachol-stimulated levels. 5. There was no selective effect among the guanine nucleotides studied on this PPI turnover event. It is, therefore, likely that these nucleotides have a direct inhibitory effect on PPI turnover, and this action may not act through a GTP-binding protein.