312 research outputs found
Некоторые результаты применения метода геометрического анализа дизъюнктов для поисков смещенного крыла пласта в Прокопьевском районе Кузбасса
In this paper we present the development of a compact, thermo-optically stable and vibration and mechanical shock resistant mounting technique by soldering of optical components. Based on this technique, new generations of laser pump sources for aerospace applications are designed. In these laser systems the used soldering technique replaces the glued connection between the optical component and its join partner. The main challenges are the alignment accuracy in the arc second range and the realization of the long term stability of every single part in the laser system (e.g. resonator mirrors)
О необходимости прослеживания Балейско-Дарасунского разлома в пределах Борщевочного кряжа
In this paper we present the development of a compact, thermo-optically stable and vibration and mechanical shock resistant mounting technique by soldering of optical components. Based on this technique a new generation of laser sources for aerospace applications is designed. In these laser systems solder technique replaces the glued and bolted connections between optical component, mount and base plate. Alignment precision in the arc second range and realization of long term stability of every single part in the laser system is the main challenge. At the Fraunhofer Institute for Laser Technology ILT a soldering and mounting technique has been developed for high precision packaging. The specified environmental boundary conditions (e.g. a temperature range of -40 °C to +50 °C) and the required degrees of freedom for the alignment of the components have been taken into account for this technique. In general the advantage of soldering compared to gluing is that there is no outgassing. In addition no flux is needed in our special process. The joining process allows multiple alignments by remelting the solder. The alignment is done in the liquid phase of the solder by a 6 axis manipulator with a step width in the nm range and a tilt in the arc second range. In a next step the optical components have to pass the environmental tests. The total misalignment of the component to its adapter after the thermal cycle tests is less than 10 arc seconds. The mechanical stability tests regarding shear, vibration and shock behavior are well within the requirements
Моделирование уравнений проекционного осциллографирования на машине "ЭМУ-10"
The passive-alignment-packaging technique presented in this work provides a method for mounting tolerance-insensitive optical components e.g. non-linear crystals by means of mechanical stops. The requested tolerances for the angle deviation are ±100 µrad and for the position tolerance ±100 µm. Only the angle tolerances were investigated, because they are more critical. The measurements were carried out with an autocollimator. Fused silica components were used for test series. A solder investigation was carried out. Different types of solder were tested. Due to good solderability on air and low induced stress in optical components, Sn based solders were indicated as the most suitable solders. In addition several concepts of reflow soldering configuration were realized. In the first iteration a system with only the alignment of the yaw angle was implemented. The deviation for all materials after the thermal and mechanical cycling was within the tolerances. The solderability of BBO and LBO crystals was investigated and concepts for mounting were developed
Erythrocyte Inosine triphosphatase activity: A potential biomarker for adverse events during combination antiretroviral therapy for HIV
The purine analogues tenofovir and abacavir are precursors of potential substrates for the enzyme Inosine 5’-triphosphate pyrophosphohydrolase (ITPase). Here, we investigated the association of ITPase activity and ITPA genotype with the occurrence of adverse events (AEs) during combination antiretroviral therapy (cART) for human immunodeficiency virus (HIV) infection. In 393 adult HIV-seropositive patients, AEs were defined as events that led to stop of cART regimen. ITPase activity 4 mmol IMP/mmol Hb/hour was considered as normal. ITPA genotype was determined by testing two ITPA polymorphisms: c.94C>A (p. Pro32Thr, rs1127354) and c.124+21A>C (rs7270101). Logistic regression analysis determined odds ratios for developing AEs. In tenofovir-containing regimens decreased ITPase activity was associated with less AEs (p = 0.01) and longer regimen duration (p = 0.001). In contrast, in abacavir-containing regimens decreased ITPase activity was associated with more AEs (crude p = 0.02) and increased switching of medication due to AEs (p = 0.03). ITPA genotype wt/wt was significantly associated with an increase in the occurrence of AEs in tenofovir-containing regimens. Decreased ITPase activity seems to be protective against occurrence of AEs in tenofovir-containing cART, while it is associated with an increase in AEs in abacavir-containing regimens
Tumor markers in breast cancer - European Group on Tumor Markers recommendations
Recommendations are presented for the routine clinical use of serum and tissue-based markers in the diagnosis and management of patients with breast cancer. Their low sensitivity and specificity preclude the use of serum markers such as the MUC-1 mucin glycoproteins ( CA 15.3, BR 27.29) and carcinoembryonic antigen in the diagnosis of early breast cancer. However, serial measurement of these markers can result in the early detection of recurrent disease as well as indicate the efficacy of therapy. Of the tissue-based markers, measurement of estrogen and progesterone receptors is mandatory in the selection of patients for treatment with hormone therapy, while HER-2 is essential in selecting patients with advanced breast cancer for treatment with Herceptin ( trastuzumab). Urokinase plasminogen activator and plasminogen activator inhibitor 1 are recently validated prognostic markers for lymph node-negative breast cancer patients and thus may be of value in selecting node-negative patients that do not require adjuvant chemotherapy. Copyright (C) 2005 S. Karger AG, Basel
Dutch National Round Robin Trial on Plasma-Derived Circulating Cell-Free DNA Extraction Methods Routinely Used in Clinical Pathology for Molecular Tumor Profiling
BACKGROUND: Efficient recovery of circulating tumor DNA (ctDNA) depends on the quantity and quality of circulating cell-free DNA (ccfDNA). Here, we evaluated whether various ccfDNA extraction methods routinely applied in Dutch laboratories affect ccfDNA yield, ccfDNA integrity, and mutant ctDNA detection, using identical lung cancer patient-derived plasma samples. METHODS: Aliquots of 4 high-volume diagnostic leukapheresis plasma samples and one artificial reference plasma sample with predetermined tumor-derived mutations were distributed among 14 Dutch laboratories. Extractions of ccfDNA were performed according to local routine standard operating procedures and were analyzed at a central reference laboratory for mutant detection and assessment of ccfDNA quantity and integrity. RESULTS: Mutant molecule levels in extracted ccfDNA samples varied considerably between laboratories, but there was no indication of consistent above or below average performance. Compared to silica membrane-based methods, samples extracted with magnetic beads-based kits revealed an overall lower total ccfDNA yield (-29%; P < 0.0001) and recovered fewer mutant molecules (-41%; P < 0.01). The variant allelic frequency and sample integrity were similar. In samples with a higher-than-average total ccfDNA yield, an augmented recovery of mutant molecules was observed. CONCLUSIONS: In the Netherlands, we encountered diversity in preanalytical workflows with potential consequences on mutant ctDNA detection in clinical practice. Silica membrane-based methodologies resulted in the highest total ccfDNA yield and are therefore preferred to detect low copy numbers of relevant mutations. Harmonization of the extraction workflow for accurate quantification and sensitive detection is required to prevent introduction of technical divergence in the preanalytical phase and reduce interlaboratory discrepancies
External Quality Assessment on Molecular Tumor Profiling with Circulating Tumor DNA-Based Methodologies Routinely Used in Clinical Pathology within the COIN Consortium
BackgroundIdentification of tumor-derived variants in circulating tumor DNA (ctDNA) has potential as a sensitive and reliable surrogate for tumor tissue-based routine diagnostic testing. However, variations in pre(analytical) procedures affect the efficiency of ctDNA recovery. Here, an external quality assessment (EQA) was performed to determine the performance of ctDNA mutation detection work flows that are used in current diagnostic settings across laboratories within the Dutch COIN consortium (ctDNA on the road to implementation in The Netherlands).MethodsAliquots of 3 high-volume diagnostic leukapheresis (DLA) plasma samples and 3 artificial reference plasma samples with predetermined mutations were distributed among 16 Dutch laboratories. Participating laboratories were requested to perform ctDNA analysis for BRAF exon 15, EGFR exon 18–21, and KRAS exon 2–3 using their regular circulating cell-free DNA (ccfDNA) analysis work flow. Laboratories were assessed based on adherence to the study protocol, overall detection rate, and overall genotyping performance.ResultsA broad range of preanalytical conditions (e.g., plasma volume, elution volume, and extraction methods) and analytical methodologies (e.g., droplet digital PCR [ddPCR], small-panel PCR assays, and next-generation sequencing [NGS]) were used. Six laboratories (38%) had a performance score of >0.90; all other laboratories scored between 0.26 and 0.80. Although 13 laboratories (81%) reached a 100% overall detection rate, the therapeutically relevant EGFR p.(S752_I759del) (69%), EGFR p.(N771_H773dup) (50%), and KRAS p.(G12C) (48%) mutations were frequently not genotyped accurately.ConclusionsDivergent (pre)analytical protocols could lead to discrepant clinical outcomes when using the same plasma samples. Standardization of (pre)analytical work flows can facilitate the implementation of reproducible liquid biopsy testing in the clinical routine
Total and caspase-cleaved cytokeratin 18 in chronic cholecystitis: A prospective study
<p>Abstract</p> <p>Background</p> <p>Cell death mode has been studied in cancer, autoimmune, and neurodegenerative diseases. In this study, apoptosis and necrosis are investigated for the first time in patients with chronic calculous cholecystitis.</p> <p>Methods and materials</p> <p>Thirty five (35) patients (27 women and 8 men, aged 55.65 ± 13.48 years) with symptomatic chronic calculous cholecystitis underwent laparoscopic cholecystectomy. The early specific apoptotic tendency (caspase-cleaved cytokeratin 18) was studied in these patients with M30 Apoptosense ELISA and the total cytokerarin 18 (both derived from apoptosis and necrosis) with M65 ELISA. The ratio M30/M65 (caspase-cleaved to total cytokeratin 18) was also computed. According to the histopathological examination, the patients were divided in two groups: group A included patients with chronic inactive cholecystitis (n = 10), and group B those with chronic active cholecystitis (n = 25).</p> <p>Results</p> <p>The concentrations of caspase-cleaved cytokerarin 18 (CK18), and especially those of total CK18, were higher in bile samples than in serum samples. In group B, there were significant differences between serum and bile samples regarding both caspase-cleaved CK18 and total CK18. Cells staining positive for caspase-cleaved CK18 were present in the epithelial cells of the mucosa of the gallbladder.</p> <p>Conclusion</p> <p>CK18 is expressed in the gallbladder epithelial cells. The concentrations of both caspase-cleaved CK18 and total CK18 were higher in bile samples than in serum samples. The levels of total CK18, as well as caspase-cleaved CK18, do not seem to differ between active and inactive chronic cholecystitis.</p
CTCF induces histone variant incorporation, erases the H3K27me3 histone mark and opens chromatin
Insulators functionally separate active chromatin domains frominactive ones. The insulator factor, CTCF, has been found to bind to boundaries and to mediate insulator function. CTCF binding sites are depleted for the histone modification H3K27me3 and are enriched for the histone variant H3.3. In order to determine whether demethylation of H3K27me3 and H3.3 incorporation are a requirement for CTCF binding at domain boundaries or whether CTCF causes these changes, we made use of the LacI DNA binding domain to control CTCF binding by the Lac inducer IPTG. Here we show that, in contrast to the related factor CTCFL, the N-terminus plus zinc finger domain of CTCF is sufficient to open compact chromatin rapidly. This is preceded by incorporation of the histone variant H3.3, which thereby removes the H3K27me3 mark. This demonstrates the causal role for CTCF in generating the chromatin features found at insulators. Thereby, spreading of a histone modification from one domain through the insulator into the neighbouring domain is inhibited
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