58 research outputs found
Prognosis in human glioblastoma based on expression of ligand growth hormone-releasing hormone, pituitary-type growth hormone-releasing hormone receptor, its splicing variant receptors, EGF receptor and PTEN genes
Purpose G lioblastoma (GB) is the most frequent brain
tumor. Despite recent improvement in therapeutic strategies,
the prognosis of GB remains poor. Growth hormone-releasing
hormone (GHRH) may act as a growth factor; antagonists
of GHRH have been successfully applied for experimental
treatment of different types of tumors. The expression profile
of GHRH receptor, its main splice variant SV1 and GHRH
have not been investigated in human GB tissue samples.
Methods We examined the expression of GHRH, fulllength
pituitary-type GHRH receptor (pGHRHR), its functional
splice variant SV1 and non-functional SV2 by RTPCR
in 23 human GB specimens. Epidermal growth factor
receptor (EGFR) and phosphatase and tensin homolog gene
(PTEN) expression levels were also evaluated by quantitative
RT-PCR. Correlations between clinico-pathological
parameters and gene expressions were analyzed.
Results E xpression of GHRH was found to be positive
in 61.9 % of samples. pGHRH receptor was not expressed
in our sample set, while SV1 could be detected in 17.4 %
and SV2 in 8.6 % of the GB tissues. In 65.2 and 78.3 %
of samples, significant EGFR over-expression or PTEN
under-representation could be detected, respectively. In
47.8 % of cases, EGFR up-regulation and PTEN down-regulation
occurred together. Survival was significantly poorer
in tumors lacking GHRH expression. This worse prognosis
in GHRH negative group remained significant even if SV1
was also expressed.
Conclusion Our study shows that GHRH and SV1 genes
expressed in human GB samples and their expression patterns
are associated with poorer prognosis
An Investigation of Surface-Enhanced Raman Scattering of Different Analytes Adsorbed on Gold Nanoislands
In this study, metallic nanoislands were prepared by thermal annealing of gold thin film produced by vacuum evaporation on a glass substrate to investigate the surface-enhanced Raman scattering (SERS) effect on them. The influence of the analyte on the enhancement factor of SERS was studied with riboflavin and rhodamine 6G dye. Two laser excitation sources at 532 and 633 nm wavelengths were used for SERS measurements. We found that the enhancement factors of the gold nanoisland SERS substrates were influenced by the analytes’ adsorption tendency onto their surfaces. The SERS amplification was also found to be dependent on the electronic structure of the molecules; higher enhancement factors were obtained for rhodamine 6G with 532 nm excitation, while for riboflavin the 633 nm source performed better
PARP1 Inhibition Augments UVB-Mediated Mitochondrial Changes-Implications for UV-Induced DNA Repair and Photocarcinogenesis
L
False Morphology of Aerogels Caused by Gold Coating for SEM Imaging
The imaging of non-conducting materials by scanning electron microscopy (SEM) is most often performed after depositing few nanometers thick conductive layers on the samples. It is shown in this work, that even a 5 nm thick sputtered gold layer can dramatically alter the morphology and the surface structure of many different types of aerogels. Silica, polyimide, polyamide, calcium-alginate and cellulose aerogels were imaged in their pristine forms and after gold sputtering utilizing low voltage scanning electron microscopy (LVSEM) in order to reduce charging effects. The morphological features seen in the SEM images of the pristine samples are in excellent agreement with the structural parameters of the aerogels measured by nitrogen adsorption-desorption porosimetry. In contrast, the morphologies of the sputter coated samples are significantly distorted and feature nanostructured gold. These findings point out that extra care should be taken in order to ensure that gold sputtering does not cause morphological artifacts. Otherwise, the application of low voltage scanning electron microscopy even yields high resolution images of pristine non-conducting aerogels
The strong in vivo anti-tumor effect of the UIC2 monoclonal antibody is the combined result of Pgp inhibition and antibody dependent cell-mediated cytotoxicity
Synthesis and Stabilization of Support-Free Mesoporous Gold Nanoparticles
Porous gold nanoparticles (PGNs) are usually prepared in an immobilized form on a solid substrate, which is not practical in many applications. In this work, a simple method is reported for the preparation and stabilization of mesoporous gold particles of a few hundred nanometers in size in aqueous suspension. Nanoparticles of Ag-Au alloy were fabricated on CaF 2 and Si/SiO 2 substrates by the solid-state dewetting method. Silver was selectively dissolved (dealloyed), and the resulting porous gold nanoparticles were chemically removed from the substrate either in a concerted step with dealloying, or in a subsequent step. Nitric acid was used for the one-step dealloying and detachment of the particles from CaF 2 substrate. The consecutive use of HNO 3 and HF resulted in the dealloying and the subsequent detachment of the particles from Si/SiO 2 substrate. The PGNs were recovered from the aqueous suspensions by centrifugation. The Au content of the suspensions was monitored by using elemental analysis (ICP-OES), and recovery was optimized. The morphology and the optical characteristics of the support-free PGNs were analyzed by scanning electron microscopy (SEM), dynamic light scattering spectroscopy (DLS), and near-infrared spectrophotometry (NIR). The obtained PGNs are spherical disk-shaped with a mean particle size of 765 ± 149 nm. The suspended, support-free PGNs display an ideally narrow dipole plasmon peak at around 1450 nm in the NIR spectral region. Thus, the new colloidal PGNs are ideal candidates for biomedical applications, for instance photothermal therapy
Mechanistic Explanation for Differences Between Catalytic Activities of Dissolved and Aerogel Immobilized Cu(II) Cyclen
The copper(II) complex of 1,4,7,10-tetraazacyclododecane [Cu(II)-cyclen] was covalently immobilized in mesoporous silica aerogel. This immobilization significantly alters the catalytic activity of Cu(II)-cyclen when referenced to the dissolved complex in the oxidation of phenol by H2O2 in aqueous solution. In order to understand this phenomenon, the functionalized aerogel was characterized by scanning electron microscopy (SEM), N2 porosimetry, small angle neutron scattering (SANS), infrared spectroscopy (IR) and electron paramagnetic resonance spectroscopy (EPR). Aerogel morphology is typical of mesoporous silica aerogels, and the coordination mode of Cu(II) in the immobilized complex is well-related but not identical to solution phase Cu(II)-cyclen. The mechanisms of the catalytic reactions involving dissolved and immobilized Cu(II)-cyclen were explored by fine kinetic experiments using capillary electrophoresis (CE) and on-line UV–vis spectrophotometry. Hydroquinone, pyrocatechol and the related benzoquinones were identified as the main intermediates in both reaction systems. A detailed kinetic model is postulated based on global data fitting, which clearly highlights the mechanistic differences in the two systems. Interestingly, the activation of the catalyst by H2O2 is more effective in the case of the aerogel, but the total conversion of phenol is slower due to hindered mass transport compared to using dissolved Cu(II)-cyclen
- …