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- Cossarizza, A., et al.
(author)
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Guidelines for the use of flow cytometry and cell sorting in immunological studies (second edition)
- 2019
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In: European Journal of Immunology. - : Wiley. - 0014-2980 .- 1521-4141. ; 49:10, s. 1457-1973
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Journal article (peer-reviewed)abstract
- These guidelines are a consensus work of a considerable number of members of the immunology and flow cytometry community. They provide the theory and key practical aspects of flow cytometry enabling immunologists to avoid the common errors that often undermine immunological data. Notably, there are comprehensive sections of all major immune cell types with helpful Tables detailing phenotypes in murine and human cells. The latest flow cytometry techniques and applications are also described, featuring examples of the data that can be generated and, importantly, how the data can be analysed. Furthermore, there are sections detailing tips, tricks and pitfalls to avoid, all written and peer-reviewed by leading experts in the field, making this an essential research companion.
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- Henriksson, M., et al.
(author)
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Separate functional features of proinsulin C-peptide
- 2005
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In: Cellular and Molecular Life Sciences (CMLS). - : Springer Science and Business Media LLC. - 1420-682X .- 1420-9071. ; 62:15, s. 1772-1778
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Journal article (peer-reviewed)abstract
- Proinsulin C-peptide influences a number of physiological parameters in addition to its well-established role in the parent proinsulin molecule. It is of interest as a candidate for future co-replacement therapy with insulin for patients with diabetes mellitus type 1, but specific receptors have not been identified and additional correlation with functional effects is desirable. Based on comparisons of 22 mammalian proinsulin variants, we have constructed analogues for activity studies, choosing phosphorylation of mitogen-activated protein kinases (MAPKs) in Swiss 3T3 fibroblasts for functional measurements. In this manner, we find that effective phosphorylation of MAPKs is promoted by the presence of conserved glutamic acid residues at positions 3, 11 and 27 of C-peptide and by the presence of helix-promoting residues in the N-terminal segment. Previous findings have ascribed functional roles to the C-terminal pentapeptide segment, and all results combined therefore now show the importance of different segments, suggesting that C-peptide interactions are complex or multiple. © Birkhäuser Verlag, 2005.
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- Egyud, M., et al.
(author)
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Detection of Circulating Tumor DNA in Plasma: A Potential Biomarker for Esophageal Adenocarcinoma
- 2019
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In: Annals of Thoracic Surgery. - : Elsevier BV. - 0003-4975. ; 108:2, s. 343-349
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Journal article (peer-reviewed)abstract
- Background. Recent literature has demonstrated the potential of "liquid biopsy" and detection of circulating tumor (ct)DNA as a cancer biomarker. However, to date there is a lack of data specific to esophageal adenocarcinoma (EAC). This study was conducted to determine how detection and quantification of ctDNA changes with disease burden in patients with EAC and evaluate its potential as a biomarker in this population. Methods. Blood samples were obtained from patients with stage I to IV EAC. Longitudinal blood samples were collected from a subset of patients. Imaging studies and pathology reports were reviewed to determine disease course. Tumor samples were sequenced to identify mutations. Mutations in plasma DNA were detected using custom, barcoded, patient-specific sequencing libraries. Mutations in plasma were quantified, and associations with disease stage and response to therapy were explored. Results. Plasma samples from a final cohort of 38 patients were evaluated. Baseline plasma samples were ctDNA positive for 18 patients (47%) overall, with tumor allele frequencies ranging from 0.05% to 5.30%. Detection frequency of ctDNA and quantity of ctDNA increased with stage. Data from longitudinal samples indicate that ctDNA levels correlate with and precede evidence of response to therapy or recurrence. Conclusions. ctDNA can be detected in plasma of EAC patients and correlates with disease burden. Detection of ctDNA in early-stage EAC is challenging and may limit diagnostic applications. However, our data demonstrate the potential of ctDNA as a dynamic biomarker to monitor treatment response and disease recurrence in patients with EAC. (C) 2019 by The Society of Thoracic Surgeons
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5. |
- He, H. J., et al.
(author)
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Multilaboratory Assessment of a New Reference Material for Quality Assurance of Cell-Free Tumor DNA Measurements
- 2019
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In: Journal of Molecular Diagnostics. - : Elsevier BV. - 1525-1578. ; 21:4, s. 658-676
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Journal article (peer-reviewed)abstract
- We conducted a multilaboratory assessment to determine the suitability of a new commercially available reference material with 40 cancer variants in a background of wild-type DNA at four different variant allele frequencies (VAFs): 2%, 0.50%, 0.125%, and 0%. The variants include single nucleotides, insertions, deletions, and two structural variations selected for their clinical importance and to challenge the performance of next-generation sequencing (NGS) methods. Fragmented DNA was formulated to simulate the size distribution of circulating wild-type and tumor DNA in a synthetic plasma matrix. DNA was extracted from these samples and characterized with different methods and multiple laboratories. The various extraction methods had differences in yield, perhaps because of differences in chemistry. Digital PCR assays were used to measure VAFs to compare results from different NGS methods. Comparable VAFs were observed across the different NGS methods. This multilaboratory assessment demonstrates that the new reference material is an appropriate tool to determine the analytical parameters of different measurement methods and to ensure their quality assurance.
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6. |
- Jackson, J. B., et al.
(author)
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Multiplex Preamplification of Serum DNA to Facilitate Reliable Detection of Extremely Rare Cancer Mutations in Circulating DNA by Digital PCR
- 2016
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In: Journal of Molecular Diagnostics. - : Elsevier BV. - 1525-1578. ; 18:2, s. 235-243
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Journal article (peer-reviewed)abstract
- Tumor-specific mutations can be identified in circulating, cell-free DNA in plasma or serum and may serve as a clinically relevant alternative to biopsy. Detection of tumor-specific mutations in the plasma, however, is technically challenging. First, mutant allele fractions are typically low in a large background of wild-type circulating, cell-free DNA. Second, the amount of circulating, cell-free DNA acquired from plasma is also low. Even when using digital PCR (dPCR), rare mutation detection is challenging because there is not enough circulating, cell-free DNA to run technical replicates and assay or instrument noise does not easily allow for mutation detection <0.1%. This study was undertaken to improve on the robustness of dPCR for mutation detection. A multiplexed, pre amplification step using a high-fidelity polymerase before dPCR was developed to increase total DNA and the number of targets and technical replicates that can be assayed from a single sample. We were able to detect multiple cancer-relevant mutations within tumor-derived samples down to 0.01%. Importantly, the signal/noise ratio was improved for all preamplified targets, allowing for easier discrimination of Low-abundance mutations against false-positive signal. Furthermore, we used this protocol on clinical samples to detect known, tumor-specific mutations in patient sera. This study provides a protocol for robust, sensitive detection of circulating tumor DNA for future clinical applications.
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- Medve, J, et al.
(author)
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Isotherms for adsorption of cellobiohydrolase I and II from Trichoderma reesei on microcrystalline cellulose
- 1997
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In: Applied Biochemistry and Biotechnology. - 1559-0291. ; 66:1, s. 39-56
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Journal article (peer-reviewed)abstract
- Adsorption to microcrystalline cellulose (Avicel) of pure cellobiohydrolase I and II (CBH I and CBH II) from Trichoderma reesei has been studied. Adsorption isotherms of the enzymes were measured at 4 degrees C using CBH I and CBH II alone and in reconstituted equimolar mixtures. Several models (Langmuir, Freundlich, Temkin, Jovanovic) were tested to describe the experimental adsorption isotherms. The isotherms did not follow the basic (one site) Langmuir equation that has often been used to describe adsorption isotherms of cellulases; correlation coefficients (R-2) were only 0.926 and 0.947, for CBH I and II, respectively. The experimental isotherms were best described by a model of Langmuir type with two adsorption sites and by a combined Langmuir-Freundlich model (analogous to the Hill equation); using these models the correlation coefficients were in most cases higher than 0.995. Apparent binding parameters derived from the two sites Langmuir model indicated stronger binding of CBH II compared to CBH I; the distribution coefficients were 20.7 and 3.7 L/g for the two enzymes, respectively. The binding capacity, on the other hand, was higher for CBH I, 1.0 mu mol (67 mg) per gram Avicel, compared to 0.57 mu mol/g (30 mg/g) for CBH II. The isotherms when analyzed with the combined Langmuir-Freundlich model indicated presence of unequal binding sites on cellulose and/or negative cooperativity in the binding of the enzyme molecules.
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