Temperature-dependent modulated reflectance of InAs/InGaAs/GaAs quantum dots-in-a-well infrared photodetectors

We present a photoreflectance (PR) study of multi-layer InAs quantum dot (QD) photodetector structures, incorporating InGaAs overgrown layers and positioned asymmetrically within GaAs/AlAs quantum wells (QWs). The influence of the back-surface reflections on the QD PR spectra is explained and a temperature-dependent photomodulation mechanism is discussed. The optical interband transitions originating from the QD/QW ground- and excited-states are revealed and their temperature behaviour in the range of 3–300 K is established. In particular, we estimated the activation energy (∼320 meV) of exciton thermal escape from QD to QW bound-states at high temperatures. Furthermore, from the obtained Varshni parameters, a strain-driven partial decomposition of the InGaAs cap layer is determined

Temperature-dependent modulated reflectance and photoluminescence of InAs-GaAs and InAs-InGaAs-GaAs quantum dot heterostructures

Optical transitions and electronic properties of epitaxial InAs quantum dots (QDs) grown with and without InGaAs strain-relieving capping layer within GaAs/AlAs quantum well (QW) are investigated. Modulated reflectance and photoluminescence spectroscopy is used to probe the QD- and QW-related interband optical transitions over the temperature range of 3–300 K. The observed spectral features in QDs are identified using numerical calculations in a framework of 8-band k⋅p k⋅p method. It is found that covering the dots by a 5 nm-thick InGaAs layer yields the energy red-shift of ground-state transition by ∼150 meV ∼150 meV . Moreover, the analysis of interband transition energy dependence on temperature using Varshni expression shows that material composition of InAs QDs significantly changes due to Ga/In interdiffusion. A comparison of emission- and absorption-type spectroscopy applied for InAs–GaAs QDs indicates a Stokes shift of ∼0.02 meV ∼0.02 meV above 150 K temperature

Onlinebasierte, qualifizierte Zweitmeinung für Patienten mit kolorektalem Karzinom — eine Pilotstudie der Felix Burda Stiftung in Zusammenarbeit mit dem Netzwerk gegen Darmkrebs

BACKGROUND Modern, individualised therapies can improve the survival of patients with colorectal cancer. However, not all patients are referred for treatment to a certified colorectal cancer centre, where a tumor board supports the implementation of their therapy in accordance to guidelines. This study examines the feasibility and demand of a structured, online-based, qualified second opinion for patients with colorectal cancer. METHOD A 15-month pilot study between 2009 and 2011, offered patients with colorectal cancer to obtain a qualified second opinion of a tumour board based on an electronic patient record completed online with the assistance of a case manager. Life-satisfaction levels and quality of life (EORCT QLQ-C30) of the participants has been monitored for a year. RESULTS In 95 % of the cases, a complete electronic patient record and a second opinion could be generated. Less than half of the participants received their first therapy recommendation from a clinic with a tumour board. The second opinion confirmed the initial medical opinion in 40 % of the cases - 33 % showed a partial and 27 % showed a significant deviation. In case of a deviation, the implementation of the second opinion improved the patients' quality of life. CONCLUSION Generating an online-based, qualified second opinion by an interdisciplinary tumour board is technically and logistically well feasible. The online-based second opinion could significantly improve the quality of treatment for patients with colorectal cancer in the future and thus improve their quality of life.HINTERGRUND Moderne, individualisierte Therapien können das Überleben von Patienten mit kolorektalem Karzinom verbessern. Jedoch werden nicht alle Patienten zur Behandlung in ein zertifiziertes Darmkrebszentrum überwiesen, wo ihre Therapie, unterstützt durch ein Tumorboard, leitliniengerecht durchgeführt wird. Daher wird derzeit die Zweitmeinung bei Krebserkrankungen diskutiert. Diese Studie beschreibt Ergebnisse einer Pilotstudie hinsichtlich der Machbarkeit und des Bedarfs einer strukturierten, onlinebasierten, qualifizierten Zweitmeinung für Patienten mit kolorektalem Karzinom. METHODEN Im Rahmen einer 15-monatigen Pilotphase zwischen 2009 und 2011 konnten Patienten mit kolorektalem Karzinom mittels einer onlinebasierten Elektronischen Patientenakte, unterstützt durch einen Case Manager, kostenfrei eine qualifizierte Zweitmeinung eines Tumorboards einholen. Ihre Zufriedenheit und ihre Lebensqualität (EORCT QLQ-C30) wurden über ein Jahr nachbeobachtet. ERGEBNISSE In 95 % der Fälle konnten eine vollständige Elektronische Patientenakte und eine Zweitmeinung erstellt werden. Weniger als die Hälfte der Teilnehmer erhielt die erste Therapieempfehlung aus einer Klinik mit Tumorboard. Die Erstmeinung konnte in 40 % der Fälle durch die Zweitmeinung bestätigt werden, in 33 % zeigte sich ein teilweises, in 27 % ein deutliches Abweichen. Bei Umsetzung der abweichenden Zweitmeinung verbesserte sich die Lebensqualität der Patienten. SCHLUSSFOLGERUNG Die Erstellung einer onlinebasierten, qualifizierten Zweitmeinung durch ein interdisziplinäres Tumorboard ist technisch und logistisch gut durchführbar. Die onlinebasierte Zweitmeinung könnte zukünftig die Qualität der Behandlung von Patienten mit kolorektalem Karzinom deutlich verbessern und damit ihre Lebensqualität erhöhen

Sample preparation procedure for the determination of polycyclic aromatic hydrocarbons in petroleum vacuum residue and bitumen

This paper describes a novel method of sample preparation for the determination of trace concentrations of polycyclic aromatic hydrocarbons (PAHs) in high-boiling petroleum products. Limits of quantitation of the investigated PAHs in materials of this type range from tens of nanograms per kilogram to <20 μg/kg. The studies revealed that in order to separate most of interferences from the analytes without a significant loss of PAHs, it is necessary to use size exclusion chromatography as the first step of sample preparation, followed by adsorption using normal-phase liquid chromatography. The use of orthogonal separation procedure described in the paper allows the isolation of only a group of unsubstituted and substituted aromatic hydrocarbons with a specific range of molar mass. The lower the required limit of quantitation of PAHs, the larger is the scale of preparative liquid chromatography in both steps of sample preparation needed. The use of internal standard allows quantitative results to be corrected for the degree of recovery of PAHs during the sample preparation step. Final determination can be carried out using HPLC-FLD, GC-MS, or HPLC-UV–VIS/DAD. The last technique provides a degree of identification through the acquired UV–VIS spectra

Expression Profiling of Rectal Tumors Defines Response to Neoadjuvant Treatment Related Genes

To date, no effective method exists that predicts the response to preoperative chemoradiation (CRT) in locally advanced rectal cancer (LARC). Nevertheless, identification of patients who have a higher likelihood of responding to preoperative CRT could be crucial in decreasing treatment morbidity and avoiding expensive and time-consuming treatments. The aim of this study was to identify signatures or molecular markers related to response to pre-operative CRT in LARC. We analyzed the gene expression profiles of 26 pre-treatment biopsies of LARC (10 responders and 16 non-responders) without metastasis using Human WG CodeLink microarray platform. Two hundred and fifty seven genes were differentially over-expressed in the responder patient subgroup. Ingenuity Pathway Analysis revealed a significant ratio of differentially expressed genes related to cancer, cellular growth and proliferation pathways, and c-Myc network. We demonstrated that high Gng4, c-Myc, Pola1, and Rrm1 mRNA expression levels was a significant prognostic factor for response to treatment in LARC patients (p<0.05). Using this gene set, we were able to establish a new model for predicting the response to CRT in rectal cancer with a sensitivity of 60% and 100% specificity. Our results reflect the value of gene expression profiling to gain insight about the molecular pathways involved in the response to treatment of LARC patients. These findings could be clinically relevant and support the use of mRNA levels when aiming to identify patients who respond to CRT therapy.C, CC and AB were supported by projects CTS2200 and PI-0710-2013 of Junta de Andalucía, TIN2013-41990-R of Programa Estatal I+D+i MINECO, and GREIB PYR_2010-02 and 2010_05 of University of Granada

Activation and cleavage of SASH1 by caspase-3 mediates an apoptotic response

Apoptosis is a highly regulated cellular process that functions to remove undesired cells from multicellular organisms. This pathway is often disrupted in cancer, providing tumours with a mechanism to avoid cell death and promote growth and survival. The putative tumour suppressor, SASH1 (SAM and SH3 domain containing protein 1), has been previously implicated in the regulation of apoptosis; however, the molecular role of SASH1 in this process is still unclear. In this study, we demonstrate that SASH1 is cleaved by caspase-3 following UVC-induced apoptosis. Proteolysis of SASH1 enables the C-terminal fragment to translocate from the cytoplasm to the nucleus where it associates with chromatin. The overexpression of wild-type SASH1 or a cleaved form of SASH1 representing amino acids 231–1247 leads to an increase in apoptosis. Conversely, mutation of the SASH1 cleavage site inhibits nuclear translocation and prevents the initiation of apoptosis. SASH1 cleavage is also required for the efficient translocation of the transcription factor nuclear factor-κB (NF-κB) to the nucleus. The use of the NF-κB inhibitor DHMEQ demonstrated that the effect of SASH1 on apoptosis was dependent on NF-κB, indicating a codependence between SASH1 and NF-κB for this process

Environmental occurrence, analysis, and toxicology of toxaphene compounds.

Toxaphene production, in quantities similar to those of polychlorinated biphenyls, has resulted in high toxaphene levels in fish from the Great Lakes and in Arctic marine mammals (up to 10 and 16 microg g-1 lipid). Because of the large variabiliity in total toxaphene data, few reliable conclusions can be drawn about trends or geographic differences in toxaphene concentrations. New developments in mass spectrometric detection using either negative chemical ionization or electron impact modes as well as in multidimensional gas chromatography recently have led researchers to suggest congener-specific approaches. Recently, several nomenclature systems have been developed for toxaphene compounds. Although all systems have specific advantages and limitations, it is suggested that an international body such as the International Union of Pure and Applied Chemistry make an attempt to obtain uniformity in the literature. Toxicologic information on individual chlorobornanes is scarce, but some reports have recently appeared. Neurotoxic effects of toxaphene exposure such as those on behavior and learning have been reported. Technical toxaphene and some individual congeners were found to be weakly estrogenic in in vitro test systems; no evidence for endocrine effects in vivo has been reported. In vitro studies show technical toxaphene and toxaphene congeners to be mutagenic. However, in vivo studies have not shown genotoxicity; therefore, a nongenotoxic mechanism is proposed. Nevertheless, toxaphene is believed to present a potential carcinogenic risk to humans. Until now, only Germany has established a legal tolerance level for toxaphene--0.1 mg kg-1 wet weight for fish

Genomic and oncoproteomic advances in detection and treatment of colorectal cancer

<p>Abstract</p> <p>Aims</p> <p>We will examine the latest advances in genomic and proteomic laboratory technology. Through an extensive literature review we aim to critically appraise those studies which have utilized these latest technologies and ascertain their potential to identify clinically useful biomarkers.</p> <p>Methods</p> <p>An extensive review of the literature was carried out in both online medical journals and through the Royal College of Surgeons in Ireland library.</p> <p>Results</p> <p>Laboratory technology has advanced in the fields of genomics and oncoproteomics. Gene expression profiling with DNA microarray technology has allowed us to begin genetic profiling of colorectal cancer tissue. The response to chemotherapy can differ amongst individual tumors. For the first time researchers have begun to isolate and identify the genes responsible. New laboratory techniques allow us to isolate proteins preferentially expressed in colorectal cancer tissue. This could potentially lead to identification of a clinically useful protein biomarker in colorectal cancer screening and treatment.</p> <p>Conclusion</p> <p>If a set of discriminating genes could be used for characterization and prediction of chemotherapeutic response, an individualized tailored therapeutic regime could become the standard of care for those undergoing systemic treatment for colorectal cancer. New laboratory techniques of protein identification may eventually allow identification of a clinically useful biomarker that could be used for screening and treatment. At present however, both expression of different gene signatures and isolation of various protein peaks has been limited by study size. Independent multi-centre correlation of results with larger sample sizes is needed to allow translation into clinical practice.</p

Three-gene predictor of clinical outcome for gastric cancer patients treated with chemotherapy

To identify transcriptional profiles predictive of the clinical benefit of cisplatin and fluorouracil (CF) chemotherapy to gastric cancer patients, endoscopic biopsy samples from 96 CF-treated metastatic gastric cancer patients were prospectively collected before therapy and analyzed using high-throughput transcriptional profiling and array comparative genomic hybridization. Transcriptional profiling identified 917 genes that are correlated with poor patient survival after CF at P<0.05 (poor prognosis signature), in which protein synthesis and DNA replication/recombination/repair functional categories are enriched. A survival risk predictor was then constructed using genes, which are included in the poor prognosis signature and are contained within identified genomic amplicons. The combined expression of three genes—MYC, EGFR and FGFR2—was an independent predictor for overall survival of 27 CF-treated patients in the validation set (adjusted P=0.017), and also for survival of 40 chemotherapy-treated gastric cancer patients in a published data set (adjusted P=0.026). Thus, combined expression of MYC, EGFR and FGFR2 is predictive of poor survival in CF-treated metastatic gastric cancer patients

Tobacco use induces anti-apoptotic, proliferative patterns of gene expression in circulating leukocytes of Caucasian males

Abstract Background Strong epidemiologic evidence correlates tobacco use with a variety of serious adverse health effects, but the biological mechanisms that produce these effects remain elusive. Results We analyzed gene transcription data to identify expression spectra related to tobacco use in circulating leukocytes of 67 Caucasian male subjects. Levels of cotinine, a nicotine metabolite, were used as a surrogate marker for tobacco exposure. Significance Analysis of Microarray and Gene Set Analysis identified 109 genes in 16 gene sets whose transcription levels were differentially regulated by nicotine exposure. We subsequently analyzed this gene set by hyperclustering, a technique that allows the data to be clustered by both expression ratio and gene annotation (e.g. Gene Ontologies). Conclusion Our results demonstrate that tobacco use affects transcription of groups of genes that are involved in proliferation and apoptosis in circulating leukocytes. These transcriptional effects include a repertoire of transcriptional changes likely to increase the incidence of neoplasia through an altered expression of genes associated with transcription and signaling, interferon responses and repression of apoptotic pathways