University of Groningen

About: University of Groningen is a education organization based out in Groningen, Groningen, Netherlands. It is known for research contribution in the topics: Population & Poison control. The organization has 36346 authors who have published 69116 publications receiving 2940370 citations. The organization is also known as: Rijksuniversiteit Groningen & RUG.

Three biomarkers identified from serum proteomic analysis for the detection of early stage ovarian cancer

Abstract: Early detection remains the most promising approach to improve long-term survival of patients with ovarian cancer. In a five-center case-control study, serum proteomic expressions were analyzed on 153 patients with invasive epithelial ovarian cancer, 42 with other ovarian cancers, 166 with benign pelvic masses, and 142 healthy women. Data from patients with early stage ovarian cancer and healthy women at two centers were analyzed independently and the results cross-validated to discover potential biomarkers. The results were validated using the samples from two of the remaining centers. After protein identification, biomarkers for which an immunoassay was available were tested on samples from the fifth center, which included 41 healthy women, 41 patients with ovarian cancer, and 20 each with breast, colon, and prostate cancers. Three biomarkers were identified as follows: (a) apolipoprotein A1 (down-regulated in cancer); (b) a truncated form of transthyretin (down-regulated); and (c) a cleavage fragment of inter-alpha-trypsin inhibitor heavy chain H4 (up-regulated). In independent validation to detect early stage invasive epithelial ovarian cancer from healthy controls, the sensitivity of a multivariate model combining the three biomarkers and CA125 [74% (95% CI, 52-90%)] was higher than that of CA125 alone [65% (95% CI, 43-84%)] at a matched specificity of 97% (95% CI, 89-100%). When compared at a fixed sensitivity of 83% (95% CI, 61-95%), the specificity of the model [94% (95% CI, 85-98%)] was significantly better than that of CA125 alone [52% (95% CI, 39-65%)]. These biomarkers demonstrated the potential to improve the detection of early stage ovarian cancer.

In situ XPS analysis of various iron oxide films grown by NO2-assisted molecular-beam epitaxy

Abstract: We report on a systematic analysis of x-ray photoelectron spectroscopy (XPS) core- and valence-level spectra of clean and well-characterized iron oxide films, i.e., $\ensuremath{\alpha}\ensuremath{-}{\mathrm{Fe}}_{2}{\mathrm{O}}_{3},$ $\ensuremath{\gamma}\ensuremath{-}{\mathrm{Fe}}_{2}{\mathrm{O}}_{3},$ ${\mathrm{Fe}}_{3\mathrm{\ensuremath{-}}\mathrm{\ensuremath{\delta}}}{\mathrm{O}}_{4},$ and ${\mathrm{Fe}}_{3}{\mathrm{O}}_{4}.$ All iron oxide films were prepared epitaxially by ${\mathrm{NO}}_{2}$-assisted molecular-beam epitaxy on single crystalline MgO(100) and $\ensuremath{\alpha}\ensuremath{-}{\mathrm{Al}}_{2}{\mathrm{O}}_{3}(0001)$ substrates. The phase and stoichiometry of the films were controlled precisely by adjusting the ${\mathrm{NO}}_{2}$ pressure during growth. The XPS spectrum of each oxide clearly showed satellite structures. These satellite structures were simulated using a cluster-model calculation, which could well reproduce the observed structures by considering the systematic changes in both the Fe $3d$ to O $2p$ hybridization and the $d\ensuremath{-}d$ electron-correlation energy. The small difference in the satellite structures between $\ensuremath{\alpha}\ensuremath{-}{\mathrm{Fe}}_{2}{\mathrm{O}}_{3}$ and $\ensuremath{\gamma}\ensuremath{-}{\mathrm{Fe}}_{2}{\mathrm{O}}_{3}$ resulted mainly from changes in the Fe-O hybridization parameters, suggesting an increased covalency in $\ensuremath{\gamma}\ensuremath{-}{\mathrm{Fe}}_{2}{\mathrm{O}}_{3}$ compared to $\ensuremath{\alpha}\ensuremath{-}{\mathrm{Fe}}_{2}{\mathrm{O}}_{3}.$ With increasing reduction in the $\ensuremath{\gamma}\ensuremath{-}{\mathrm{Fe}}_{2}{\mathrm{O}}_{3}{\ensuremath{-}\mathrm{F}\mathrm{e}}_{3}{\mathrm{O}}_{4}$ system, the satellite structures in XPS became unresolved. This was not only due to the formation of ${\mathrm{Fe}}^{2+}$ ions, but also to nonhomogeneous changes in the hybridization parameters between octahedral and tetrahedral ${\mathrm{Fe}}^{3+}$ ions.