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The criteria for assessing the quality of rubber materials are the polymer or copolymer composition and the additives. These additives include plasticizers, extender oils, carbon black, inorganic fillers, antioxidants, heat and light stabilizers, processing aids, cross-linking agents, accelerators, retarders, adhesives, pigments, smoke and flame retardants, and others. Determination of additives in polymers or copolymers generally requires the extraction of these substances from the matrix as a first step, which can be challenging, and the subsequent analysis of the extracted additives by gas chromatography (GC), GC-mass spectrometry (MS), high performance liquid chromatography (HPLC), HPLC-MS, capillary electrophoresis, thin-layer chromatography, and other analytical techniques. In the present work, nitrile rubber materials were studied using direct analytical flash pyrolysis hyphenated to GC and electrospray ionization MS in both scan and selected ion monitoring modes to demonstrate that this technique is a good tool to identify the organic additives in nitrile rubber.
Tamoxifen therapy of invasive breast cancer has been associated with increased levels of endothelin-1 (ET-1) so that an endothelin-1 receptor (ETR) blockade has been suggested as a new therapeutic approach. This study analyzed the relationship between Tamoxifen and ET-1 signalling in invasive breast cancer. Using paraffinized tissue from 50 randomly chosen cases of invasive and in-situ ductal carcinoma from our archive, the expression of ETRs was analyzed by immune histology. ETRs were regularly detectable in normal breast tissue, but rarely in adjacent tumor areas (3/50 cases). By immunoprecipitation, a complex was found consisting of ET-1, estrogen receptors and Tamoxifen. Consequently, transcription of several target genes of ET-1 and estrogen receptors was detectable (interleukin-6, wnt-11 and a vimentin spliceform). In particular, the combination of Tamoxifen, ET-1, and estrogen receptors induced further increasing levels of these target genes. Some of these genes have been found upregulated in metastatically spreading breast cancer cells. We conclude: i) ETRs do not play a role in invasive or in-situ ductal breast cancer; ii) estrogen receptors and Tamoxifen build a complex with ET-1; and iii) upregulated transcription of target genes by ET-1–estrogen receptor–Tamoxifen complex may negatively influence breast cancer prognosis. These results indicate a role for ET-1 in Tamoxifen treated breast cancer patients leading to a potentially worsening prognosis.
Introduction: Matrix metalloproteinases (MMPs) are important in tissue remodelling. Here we investigate the role of collagenase-3 (MMP-13) in antibody-induced arthritis.
Methods: For this study we employed the K/BxN serum-induced arthritis model. Arthritis was induced in C57BL/6 wild type (WT) and MMP-13-deficient (MMP-13–/–) mice by intraperitoneal injection of 200 μl of K/BxN serum. Arthritis was assessed by measuring the ankle swelling. During the course of the experiments, mice were sacrificed every second day for histological examination of the ankle joints. Ankle sections were evaluated histologically for infiltration of inflammatory cells, pannus tissue formation and bone/cartilage destruction. Semi-quantitative PCR was used to determine MMP-13 expression levels in ankle joints of untreated and K/BxN serum-injected mice.
Results: This study shows that MMP-13 is a regulator of inflammation. We observed increased expression of MMP-13 in ankle joints of WT mice during K/BxN serum-induced arthritis and both K/BxN serum-treated WT and MMP-13–/– mice developed progressive arthritis with a similar onset. However, MMP-13–/– mice showed significantly reduced disease over the whole arthritic period. Ankle joints of WT mice showed severe joint destruction with extensive inflammation and erosion of cartilage and bone. In contrast, MMP-13–/– mice displayed significantly decreased severity of arthritis (50% to 60%) as analyzed by clinical and histological scoring methods.
Conclusions: MMP-13 deficiency acts to suppress the local inflammatory responses. Therefore, MMP-13 has a role in the pathogenesis of arthritis, suggesting MMP-13 is a potential therapeutic target.
Increased endothelin-1 decreases PKC alpha (PKCα), resulting in high miRNA 15a levels in kidney tumors. Breast cancer cells treated with ET-1, β-estrogen, Tamoxifen, Tamoxifen + β-estrogen and Tamoxifen + ET-1 were analysed regarding miRNA 15a expression. Significantly increased miRNA 15a levels were found after ET-1, becoming further increased in Tamoxifen + ET-1 treated cells. Our group already showed that miRNA 15a induces MAPK p38 splicing resulting in a truncated product called Mxi-2, whose function has yet to be defined in tumors. We described for the first time in ET-1 induced tumor cells that Mxi-2 builds a complex with Ago2, a miRNA binding protein, which is important for the localization of miRNAs to the 3′UTR of target genes. Furthermore, we show that Mxi-2/Ago2 is important for the interaction with the miRNA 1285 which binds to the 3′end of the tumor suppressor gene p53, being responsible for the downregulation of p53. Tissue arrays from breast cancer patients were performed, analysing Mxi-2, p53 and PKCα. Since the Mxi-2 levels increase in Tamoxifen + ET-1 treated cells, we claim that increasing ET-1 levels in Tamoxifen treated breast cancer patients are responsible for decreasing p53 levels. In summary, ET-1 decreases nuclear PKCα levels, while increasing the amount of miRNA 15a. This causes high levels of Mxi-2, necessary for complex formation with Ago2. The newly identified Mxi-2/Ago2 complex interacting with miRNA 1285 leads to increased 3′UTR p53 interaction, resulting in decreased p53 levels and subsequent tumor progression. This newly identified mechanism is a possible explanation for the development of ET-1 induced tumors.