70 research outputs found
Selection of the spraying technologies for over-coating of metal-stampings with thermo-plastics for use in direct-adhesion polymer metal hybrid load-bearing components
The suitability of various polymer-powder spraying technologies for coating of metal-stampings used in polymer metal hybrid (PMH) load-bearing automotive-component applications is considered. The suitability of the spraying technologies is assessed with respect to a need for metal-stamping surface preparation/treatment, their ability to deposit the polymeric material without significant material degradation, the ability to selectively overcoat the metal-stamping, the resulting magnitude of the polymer-to-metal adhesion strength, durability of the polymer/metal bond with respect to prolonged exposure to high-temperature/high-humidity and mechanical/thermal fatigue service conditions, and compatibility with the automotive body-in-white (BIW) manufacturing process chain. The analysis revealed that while each of the spraying technologies has some limitations, the cold-gas dynamic-spray process appears to be the leading candidate technology for the indicated applications
Identification and quantification of phenolic compounds in bambangan (Mangifera pajang Kort.) peels and their free radical scavenging activity.
Phenolic compounds and antioxidant capacity of acidified methanolic extract prepared from fully ripe bambangan (Mangifera pajang K.) peel cultivated in Sarawak, Malaysia, were analyzed. The total phenolic content (98.3 mg GAE/g) of bambangan peel powder (BPP) was determined by the Folin-Ciocalteu method. BPP showed a strong potency of antioxidant activity and was consistent with that of BHT and vitamin C as confirmed by the DPPH (1,1-diphenyl-2-picrylhydrazyl) radical scavenging activity and FRAP (ferric-reducing antioxidant power) assays. Gallic acid, p-coumaric acid, ellagic acid, protocatechuic acid, and mangiferin were the major compounds among the 16 phenolics that have been identified and quantified in M. pajang peels with 20.9, 12.7, 7.3, 5.4, and 4.8 mg/g BPP, respectively. Peak identities were confirmed by comparing their retention times, UV-vis absorption spectra, and mass spectra with authentic standards. The 16 phenolic compounds identified in M. pajang K. using HPLC-DAD and TSQ-ESI-MS are reported here for the first time
CD36-mediated activation of endothelial cell apoptosis by an N-terminal recombinant fragment of thrombospondin-2 inhibits breast cancer growth and metastasis in vivo
Thus far the clinical benefits seen in breast cancer patients treated with drugs targeting the vascular endothelial growth factor (VEGF) pathway are only modest. Consequently, additional antiangiogenic approaches for treatment of breast cancer need to be investigated. Thrombospondin-2 (TSP-2) has been shown to inhibit tumor growth and angiogenesis with a greater potency than the related molecule TSP-1. The systemic effects of TSP-2 on tumor metastasis and the underlying molecular mechanisms of the antiangiogenic activity of TSP-2 have remained poorly understood. We generated a recombinant fusion protein consisting of the N-terminal region of TSP-2 and the IgG-Fc1 fragment (N-TSP2-Fc) and could demonstrate that the antiangiogenic activity of N-TSP2-Fc is dependent on the CD36 receptor. We found that N-TSP2-Fc inhibited VEGF-induced tube formation of human dermal microvascular endothelial cells (HDMEC) on matrigel in vitro and that concurrent incubation of anti-CD36 antibody with N-TSP2-Fc resulted in tube formation that was comparable to untreated control. N-TSP2-Fc potently induced apoptosis of HDMEC in vitro in a CD36-dependent manner. Moreover, we could demonstrate a CD36 receptor-mediated loss of mitochondrial membrane potential and activation of caspase-3 in HDMEC in vitro. Daily intraperitoneal injections of N-TSP2-Fc resulted in a significant inhibition of the growth of human MDA-MB-435 and MDA-MB-231 tumor cells grown in the mammary gland of immunodeficient nude mice and in reduced tumor vascularization. Finally, increased serum concentrations of N-TSP2-Fc significantly inhibited regional metastasis to lymph nodes and distant metastasis to lung as shown by quantitative real-time alu PCR. These results identify N-TSP2-Fc as a potent systemic inhibitor of tumor metastasis and provide strong evidence for an important role of the CD36 receptor in mediating the antiangiogenic activity of TSP-2
Simultaneous siRNA Targeting of Src and Downstream Signaling Molecules Inhibit Tumor Formation and Metastasis of a Human Model Breast Cancer Cell Line
Src and signaling molecules downstream of Src, including signal transducer and activator of transcription 3 (Stat3) and cMyc, have been implicated in the development, maintenance and/or progression of several types of human cancers, including breast cancer. Here we report the ability of siRNA-mediated Src knock-down alone, and simultaneous knock-down of Src and Stat3 and/or cMyc to inhibit the neoplastic phenotype of a highly metastatic human model breast cancer cell line, MDA-MB-435S, a widely used model for breast cancer research.Src and its downstream signaling partners were specifically targeted and knocked-down using siRNA. Changes in the growth properties of the cultured cancer cells/tumors were documented using assays that included anchorage-dependent and -independent (in soft agar) cell growth, apoptosis, and both primary and metastatic tumor growth in the mouse tumor model. siRNA-mediated Src knock-down alone, and simultaneous knock-down of Src and Stat3 and/or cMyc inhibited the neoplastic phenotype of a highly metastatic human model breast cancer cell line, MDA-MB-435S. This knock-down resulted in reduced growth in monolayer and soft agar cultures, and a reduced ability to form primary tumors in NOD/SCID mice. In addition, direct intra-tumoral injection of siRNAs targeting these signaling molecules resulted in a substantial inhibition of tumor metastases as well as of primary tumor growth. Simultaneous knock-down of Src and Stat3, and/or Myc exhibited the greatest effects resulting in substantial inhibition of primary tumor growth and metastasis.These findings demonstrate the effectiveness of simultaneous targeting of Src and the downstream signaling partners Stat3 and/or cMyc to inhibit the growth and oncogenic properties of a human cancer cell line. This knowledge may be very useful in the development of future therapeutic approaches involving targeting of specific genes products involved in tumor growth and metastasis
Dynamics of quercetin formation in onion (Allium cepa L.) during vegetation
Onion bulbs (Allium cepa L.) are good sources of flavonoids. The aim of this study was to analyse the changes in dynamics of quercetin formation in three varieties of onions (white, yellow, and red) during the vegetation period. Quercetin content was determined after acid hydrolysis (1.2 M HCl in 50% aqueous methanol) by high-performance liquid chromatography (HPLC). The content of total phenolics was determined using Folin-Ciocalteu reagent (FCR) according to LACHMAN and co-workers (2003). The content of polyphenols in onion ranged from 2893 to 6052 mg kg–1 and the content of quercetin ranged from 52.44 to 280.72 mg kg–1 in fresh matter. The highest content of polyphenols and quercetin was found in the red variety. According to statistical analysis the dynamic of quercetin formation in all cultivars had statistically moderate (P<0.05) increasing tendency. Increasing content of polyphenols was accompanied with slight increase of quercetin, but the differences remained insignificant (P<0.05)
Stat3 Mediates Expression of Autotaxin in Breast Cancer
We determined that signal transducer and activator of transcription 3 (Stat3) is tyrosine phosphorylated in 37% of primary breast tumors and 63% of paired metastatic axillary lymph nodes. Examination of the distribution of tyrosine phosphorylated (pStat3) in primary tumors revealed heterogenous expression within the tumor with the highest levels found in cells on the edge of tumors with relatively lower levels in the central portion of tumors. In order to determine Stat3 target genes that may be involved in migration and metastasis, we identified those genes that were differentially expressed in primary breast cancer samples as a function of pStat3 levels. In addition to known Stat3 transcriptional targets (Twist, Snail, Tenascin-C and IL-8), we identified ENPP2 as a novel Stat3 regulated gene, which encodes autotaxin (ATX), a secreted lysophospholipase which mediates mammary tumorigenesis and cancer cell migration. A positive correlation between nuclear pStat3 and ATX was determined by immunohistochemical analysis of primary breast cancer samples and matched axillary lymph nodes and in several breast cancer derived cell lines. Inhibition of pStat3 or reducing Stat3 expression led to a decrease in ATX levels and cell migration. An association between Stat3 and the ATX promoter, which contains a number of putative Stat3 binding sites, was determined by chromatin immunoprecipitation. These observations suggest that activated Stat3 may regulate the migration of breast cancer cells through the regulation of ATX
Antitumour activity of Annona muricata L. leaf methanol extracts against Ehrlich Ascites Carcinoma and Dalton’s Lymphoma Ascites mediated tumours in Swiss albino mice
The use of plants as a source of sedative or treatment for cancer is reasonably widespread world-wide. Annona muricata Linn exhibits a vast array of medicinal and ethno-pharmaceutical benefits, attributed by different plant parts. The activity of this plant is regarded to the bio-production of secondary metabolites like alkaloids, phenols, flavonoids, and most unique group of compounds, namely, annonaceous acetogenins. Whilst this plant is gaining popularity as an anticancer treating plant, this study was undertaken to verify the plausible anticancer effect of leaf methanol extracts of A. muricata (LEAM). Acute toxicity study was carried to obtain safe dose in mice models using haematological, biochemical, and histological evaluations in Swiss albino mice. In-vitro cytotoxicity towards Dalton’s Lymphoma Ascites (DLA) and Ehrlich Ascites Carcinoma (EAC) cell lines were determined by trypan blue exclusion method. In-vivo antitumour activity of LEAM (100, 200, and 500mg/kg b.wt.) was evaluated using DLA induced solid carcinoma and EAC induced ascites carcinoma models and its comparison with standard drug Cisplatin. Acute toxicity studies did not exhibit significant variations in treated mice suggesting diminutive side effects of LEAM. Statistical analysis revealed the IC50 values for DLA and EAC cell lines as 85.56 ± 5.28 and 68.07 ± 7.39 μg/mL, respectively, indicating better cytotoxic activity against EAC than DLA cells. LEAM decreased the tumour burden in dose-dependent manner. In comparison, with different concentrations tested, treatment with LEAM (200 mg/kg b.wt. and 500 mg/kg b.wt.) significantly reduced the solid tumour volume development by 58.11% and 65.70%, respectively. While lifespan was prolonged up to 51.43% in 500 mg/kg b.wt. LEAM treated ascites tumour-induced mice. This study thus indicates that LEAM possesses potent cytotoxic and antineoplastic activity and calls for more methodical safety assessments and other end-points of anti-tumourigenesis.
Abbreviations: LEAM: Leaf methanol extract of Annona muricata; DLA: Dalton’s Lymphoma Ascites; EAC: Ehrlich Ascites Carcinoma; IC50: Half maximal inhibitory concentration; CPCSEA: Committee for the Purpose of Control Supervision of Experiments on Animal; IAEC: Institutional Animal Ethics Committee; ARRIVE: Animal Research: Reporting In-vivo Experiments; DMSO: Dimethyl sulphoxide; LD50: Lethal Dose, 50%; SD: Standard Deviation; Hb: Haemoglobin; RBC: Red blood cells; WBC: White blood cells; HCT: Hematocrit; MCV: Mean cell volume; MCH: Mean cell haemoglobin; MCHC: Mean cell haemoglobin concentra- tion; SALP: Serum alkaline phosphatase; SGPT: Serum glutamic pyruvic transaminase; SGOT: Serum glutamic oxaloacetic transaminase; ATP: Adenosine triphosphate; EGFR: Epidermal Growth Factor Recepto
On the mechanism of enhanced photocatalytic activity of composite TiO(2)/carbon nanofilms
In the search for the origin of the enhanced photocatalytic activity of composite TiO(2)-carbon systems, we have fabricated and analyzed well-defined model samples consisting of anatase and graphitic carbon with and without modifying the interface between them by a thin SiO(2) space layer. The films with a TiO(2)/C interface show noticeably lower photoluminescence intensity and shorter carrier life times compared to single TiO(2) films with the same thickness and composition. The stronger non-radiative recombination is mainly assigned to charge carrier leakage (transfer) at the interface between TiO(2) nanocrystallites and the carbon film. (C) 2011 Elsevier B.V. All rights reserved
Tuning light absorption by band gap engineering in ZnCdO as a function of MOVPE-synthesis conditions and annealing
Options of flow rate and growth temperature variations were investigated in order to reveal limitations for single phase wurtzite ZnCdO synthesis by atmospheric pressure metal organic vapor phase epitaxy (MOVPE). It is found that in spite of efficient Cd incorporation (up to 60%), the wurtzite phase and the corresponding single step absorption threshold dominate only up to a Cd content <= 17% in the as-grown samples. Post-fabrication anneals reveal two characteristic optical absorption edges at similar to 2.3 and similar to 3.15 eV that were associated with direct band gaps of cubic CdO and thermodynamically stable wurtzite ZnCdO, respectively
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