Prognostic DNA methylation markers for sporadic colorectal cancer: a systematic review

Background Biomarkers that can predict the prognosis of colorectal cancer (CRC) patients and that can stratify high-risk early stage patients from low-risk early stage patients are urgently needed for better management of CRC. During the last decades, a large variety of prognostic DNA methylation markers has been published in the literature. However, to date, none of these markers are used in clinical practice. Methods To obtain an overview of the number of published prognostic methylation markers for CRC, the number of markers that was validated independently, and the current level of evidence (LoE), we conducted a systematic review of PubMed, EMBASE, and MEDLINE. In addition, we scored studies based on the REMARK guidelines that were established in order to attain more transparency and complete reporting of prognostic biomarker studies. Eighty-three studies reporting on 123 methylation markers fulfilled the study entry criteria and were scored according to REMARK. Results Sixty-three studies investigated single methylation markers, whereas 20 studies reported combinations of methylation markers. We observed substantial variation regarding the reporting of sample sizes and patient characteristics, statistical analyses, and methodology. The median (range) REMARK score for the studies was 10.7 points (4.5 to 17.5) out of a maximum of 20 possible points. The median REMARK score was lower in studies, which reported a p value below 0.05 versus those, which did not (p = 0.005). A borderline statistically significant association was observed between the reported p value of the survival analysis and the size of the study population (p = 0.051). Only 23 out of 123 markers (17%) were investigated in two or more study series. For 12 markers, and two multimarker panels, consistent results were reported in two or more study series. For four markers, the current LoE is level II, for all other markers, the LoE is lower. Conclusion This systematic review reflects that adequate reporting according to REMARK and validation of prognostic methylation markers is absent in the majority of CRC methylation marker studies. However, this systematic review provides a comprehensive overview of published prognostic methylation markers for CRC and highlights the most promising markers that have been published in the last two decades

Developing Matlab scripts for image analysis and quality assessment

Image processing is a very helpful tool in many fields of modern sciences that involve digital imaging examination and interpretation. Processed images however, often need to be correlated with the original image, in order to ensure that the resulting image fulfills its purpose. Aside from the visual examination, which is mandatory, image quality indices (such as correlation coefficient, entropy and others) are very useful, when deciding which processed image is the most satisfactory. For this reason, a single program (script) was written in Matlab language, which automatically calculates eight indices by utilizing eight respective functions (independent function scripts). The program was tested in both fused hyperspectral (Hyperion-ALI) and multispectral (ALI, Landsat) imagery and proved to be efficient. Indices were found to be in agreement with visual examination and statistical observations

Developing Matlab scripts for image analysis and quality assessment

Image processing is a very helpful tool in many fields of modern sciences that involve digital imaging examination and interpretation. Processed images however, often need to be correlated with the original image, in order to ensure that the resulting image fulfills its purpose. Aside from the visual examination, which is mandatory, image quality indices (such as correlation coefficient, entropy and others) are very useful, when deciding which processed image is the most satisfactory. For this reason, a single program (script) was written in Matlab language, which automatically calculates eight indices by utilizing eight respective functions (independent function scripts). The program was tested in both fused hyperspectral (Hyperion-ALI) and multispectral (ALI, Landsat) imagery and proved to be efficient. Indices were found to be in agreement with visual examination and statistical observations

PANSHARPENING ON THE NARROW VNIR AND SWIR SPECTRAL BANDS OF SENTINEL-2

In this paper results from the evaluation of several state-of-the-art pansharpening techniques are presented for the VNIR and SWIR bands of Sentinel-2. A procedure for the pansharpening is also proposed which aims at respecting the closest spectral similarities between the higher and lower resolution bands. The evaluation included 21 different fusion algorithms and three evaluation frameworks based both on standard quantitative image similarity indexes and qualitative evaluation from remote sensing experts. The overall analysis of the evaluation results indicated that remote sensing experts disagreed with the outcomes and method ranking from the quantitative assessment. The employed image quality similarity indexes and quantitative evaluation framework based on both high and reduced resolution data from the literature didn’t manage to highlight/evaluate mainly the spatial information that was injected to the lower resolution images. Regarding the SWIR bands none of the methods managed to deliver significantly better results than a standard bicubic interpolation on the original low resolution bands

A radio resource allocation scheme for fixed broadband wireless access systems with avoidance of major interferers

An improved radio resource allocation scheme with avoidance of major interferers is proposed and analyzed for the downlink of Fixed Broadband Wireless Access (FBWA) systems with full frequency reuse. The scheme is based on Enhanced Staggered Resource Allocation (ESRA) and permits the enhancement of the throughput per sector. Simulation results show a maximum downlink throughput per sector in excess of 44% and an increase of 10% with respect to ESRA is achieved, with Base Station (BS) selection procedure, while meeting a 15 dB signal-to-interference ratio (SIR). © Springer Science+Business Media B.V. 2007

Geomorphological study of Samaria gorge (Crete) using Remote Sensing techniques and GIS

In this paper we study Samaria gorge through recognition, recording and visualization of geomorphological characteristics. Geomorphological characteristics collected through Remote Sensing techniques, are compared with those collected through stereoscopic observation of aerial photos and fieldwork. At the first phase, the aerial photos of the studied area were scanned and through selected digital image processing algorithms, the geomorphological characteristics were stressed and recorded. At the second phase a geomorphological map was created based on data derived from stereoscopic observation of the area aerial photos and fieldwork. During fieldwork a GPS was used, which was connected with the GIS in order to immediately record and test the measured characteristic position. Finally the combination of two methods took place in order to develop a geomorphological map

Heterophilic antibodies causing falsely high serum calcitonin values

Heterophilic antibodies (HA) may interfere in some immunoassays, causing falsely high hormone values, of wich practitioners should be aware when measuring calcitonin (CT) used as tumor marker for medullary thyroid carcinoma (MTC). We studied four patients with thyroid nodules, three of whom underwent surgical neck exploration, after an erroneous diagnosis of MTC because of falsely high serum CT eventually proved to be due to HA. One patient had a lingual thyroid, two autoimmune thyroiclitis and the fourth a colloid goiter. The minimal incremental CT response to calcium infusion raised our suspicion of possible false high CT values due to HA. There was no linearity of the CT values obtained by testing serial dilutions of the sera in the CT assay, which employs two monoclonal mouse anti-CT antibodies. Addition of normal mouse gamma globulin eliminated the interference by HA in the sera of two patients. Serum assayed in a polyclonal radioimmunoassay using goat anti-CT antibodies gave normal CT values. Finally, incubation of the sera in Heterophilic Blocking Tubes((R)) (HBT) eliminated the false CT immunoreactivity. A spontaneous change of the CT serum concentrations was noticed in three patients over several months, apparently due to changing titles of HA. We suggest that, in patients a) whose CT response to calcium or pentagastrin infusion is minimal despite high basal CT values, b) with autoimmune thyroiditis and c) in whom an unexpected change in serum CT concentrations occurs, the possibility of spuriously high CT values because of circulating HA should be considered