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  • 1
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    PATH-29. POTENTIAL OF RAMAN SPECTROSCOPY IN ONCOLOGICAL NEUROSURGERY
    Oxford University Press (OUP) ; 2019
    In:  Neuro-Oncology Vol. 21, No. Supplement_6 ( 2019-11-11), p. vi149-vi149
    Details
    In: Neuro-Oncology, Oxford University Press (OUP), Vol. 21, No. Supplement_6 ( 2019-11-11), p. vi149-vi149
    Abstract: Raman spectroscopy (RS) has gained increasing interest for the analysis of biological tissues within the recent years. It is a label-free, non-destructive method providing insights in biochemical properties of tumor cells. It is possible to compare RS signals with histological properties of identical tissue parts. Therefore, RS bears promising potentials in neurosurgical neurooncology. On one hand, it could potentially be used for both intraoperative tumor diagnostics and resection control. On the other hand, it could provide important knowledge on tumor biochemistry and used for a subclassification of tumors with a potential impact on personalized therapy approaches. Within our group, we analyzed over 3000 measurement points in different brain tumors ex vivo with a robotized RS system and correlated the spectral curves with histopathological results. We separated and subclassified the data by AI-based methods. Additionally, we compared the latter results with those of a handheld probe, which is potentially navigatable for in vivo, intraoperative applications. We could demonstrate, that it is possible to separate distinct tumor groups only based on RS signals, especially by using computer-based signal analysis. Furthermore, we could demonstrate the differences of the spectra of deep-frozen and formalin-fixed tissues versus non-fixed tissues. Based on our results, we will highlight the potentials of RS for intraoperative neurosurgical application in resection control for brain tumors, as well as we will focus on the potentials for brain tumor diagnostics based purely on this method or by using it as an adjunct. Those methods bear additional potentials in the field of personalized chemotherapy approaches.
    Type of Medium: Online Resource
    ISSN: 1522-8517 , 1523-5866
    URL: Article
    DOI: 10.1093/neuonc/noz175.625
    Language: English
    Publisher: Oxford University Press (OUP)
    Publication Date: 2019
    detail.hit.zdb_id: 2094060-9
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  • 2
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    The economic activities of sub-Saharan immigrants: informal sector and low wages
    EDP Sciences ; 2021
    In:  SHS Web of Conferences Vol. 119 ( 2021), p. 06001-
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    In: SHS Web of Conferences, EDP Sciences, Vol. 119 ( 2021), p. 06001-
    Abstract: Immigration is a social phenomenon that leads to the immigrant’s sociological and economic reorganization, the immigrant often finds himself obliged to overcome the challenges of the economic integration into the host society. So, this study is an analysis of the economic activities of 102 sub-Saharan immigrants who live and work in the urban space of Rabat, and one semi-structured questionnaire is used to explores the specificities of the sectors of their economic activities. The results obtained confirm the findings of various authors affirming the recourse of immigrants to informal economic activity sectors generating low wages.
    Type of Medium: Online Resource
    ISSN: 2261-2424
    URL: Article
    DOI: 10.1051/shsconf/202111906001
    Language: English
    Publisher: EDP Sciences
    Publication Date: 2021
    detail.hit.zdb_id: 2755676-1
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  • 3
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    Online Resource
    PATH-31. BUILDING A RAMAN SPECTROSCOPY REFERENCE DATABASE FOR TUMOR IDENTIFICATION AND CLASSIFICATION
    Oxford University Press (OUP) ; 2019
    In:  Neuro-Oncology Vol. 21, No. Supplement_6 ( 2019-11-11), p. vi149-vi150
    Details
    In: Neuro-Oncology, Oxford University Press (OUP), Vol. 21, No. Supplement_6 ( 2019-11-11), p. vi149-vi150
    Abstract: Brain tumor resection requires careful assessment of the nature and malignancy of the tumor tissue during intervention, as this is the basis for the decision as to how radical surgery has to be. Typically, there is no tissue available for analysis prior to the surgery. Intraoperative histopathological examination of tumor samples is time consuming and puts the patient to a significant amount of strain due to ongoing anesthesia and prolonged surgery, thus there is a need to develop faster methods for thorough diagnostics. Raman spectroscopy allows for a fast analysis of samples without the need for labeling and sample preparation, making it a useful tool for peri- and intrasurgical application. We collect Raman spectra and correlated histopathological results to build a database of different tumor types. As intrasurgical use of Raman spectroscopy will typically be applied to native specimens, the respective database has to be based on native samples as well. We collected several thousands of measurements from more than 100 patients and continue to assemble a native database. Tumors that do not occur with a high frequency are not sufficiently represented in the database. Therefore, we investigate whether it is possible to integrate fixed and frozen specimens in the collection of Raman spectra and the classifier. Fixation results in characteristic changes to the biochemistry of biological tissues. We collect pairs of spectra from native and fixed as well as from native and frozen specimens and use the difference of the spectra to create an algorithm for filtering of the specific changes in the spectra. These data can be used to train a classifier for the identification of native samples. This opens the way for assessing large collections of pathological samples in fixed and frozen state to cover any type of neoplastic disease in the database.
    Type of Medium: Online Resource
    ISSN: 1522-8517 , 1523-5866
    URL: Article
    DOI: 10.1093/neuonc/noz175.627
    Language: English
    Publisher: Oxford University Press (OUP)
    Publication Date: 2019
    detail.hit.zdb_id: 2094060-9
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  • 4
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    PATH-43. RAMAN SPECTROSCOPY AS A TOOL IN NEUROSURGERY
    Oxford University Press (OUP) ; 2021
    In:  Neuro-Oncology Vol. 23, No. Supplement_6 ( 2021-11-12), p. vi125-vi125
    Details
    In: Neuro-Oncology, Oxford University Press (OUP), Vol. 23, No. Supplement_6 ( 2021-11-12), p. vi125-vi125
    Abstract: Raman Spectra have been shown to be sufficiently characteristic to their samples of origin that they can be used in a wide range of applications including distinction of intracranial tumors. While not replacing pathological analysis, the advantage of non-destructive sample analysis and extremely fast feedback make this technique an interesting tool for surgical use. METHODS We sampled intractanial tumors from more than 300 patients at the Centre Hospitalier Luxembourg over a period of three years and compared the spectra of different tumor entities, different tumor subregions and healthy surrounding tissue. We created machine-learning based classifiers that include tissue identification as well as diagnostics. RESULTS To this end, we solved several classes in the intracranial tumor classification, and developed classifiers to distinguish primary central nervous system lymphoma from glioblastoma, which is an important differential diagnosis, as well as meningioma from the surrounding healthy dura mater for identification of tumor tissue. Within glioblastoma, we resolve necrotic, vital tumor tissue and peritumoral infiltration zone.We are currently developing a multi-class classifier incorporating all tissue types measured. CONCLUSIONS Raman Spectroscopy has the potential to aid the surgeon in the surgery theater by providing a quick assessment of the tissue analyzed with regards to both tumor identity and tumor margin identification. Once a reliable classifier based on sufficient patient samples is developed, this may even be integrated into a surgical microscope or a neuronavigation system.
    Type of Medium: Online Resource
    ISSN: 1522-8517 , 1523-5866
    URL: Article
    DOI: 10.1093/neuonc/noab196.495
    Language: English
    Publisher: Oxford University Press (OUP)
    Publication Date: 2021
    detail.hit.zdb_id: 2094060-9
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  • 5
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    TGF-Beta Modulates the Integrity of the Blood Brain Barrier In Vitro, and Is Associated with Metabolic Alterations in Pericytes
    MDPI AG ; 2023
    In:  Biomedicines Vol. 11, No. 1 ( 2023-01-14), p. 214-
    Details
    In: Biomedicines, MDPI AG, Vol. 11, No. 1 ( 2023-01-14), p. 214-
    Abstract: The blood–brain barrier (BBB) is a selectively permeable boundary that separates the circulating blood from the extracellular fluid of the brain and is an essential component for brain homeostasis. In glioblastoma (GBM), the BBB of peritumoral vessels is often disrupted. Pericytes, being important to maintaining BBB integrity, can be functionally modified by GBM cells which induce proliferation and cell motility via the TGF-β-mediated induction of central epithelial to mesenchymal transition (EMT) factors. We demonstrate that pericytes strengthen the integrity of the BBB in primary endothelial cell/pericyte co-cultures as an in vitro BBB model, using TEER measurement of the barrier integrity. In contrast, this effect was abrogated by TGF-β or conditioned medium from TGF-β secreting GBM cells, leading to the disruption of a so far intact and tight BBB. TGF-β notably changed the metabolic behavior of pericytes, by shutting down the TCA cycle, driving energy generation from oxidative phosphorylation towards glycolysis, and by modulating pathways that are necessary for the biosynthesis of molecules used for proliferation and cell division. Combined metabolomic and transcriptomic analyses further underscored that the observed functional and metabolic changes of TGF-β-treated pericytes are closely connected with their role as important supporting cells during angiogenic processes.
    Type of Medium: Online Resource
    ISSN: 2227-9059
    URL: Article
    DOI: 10.3390/biomedicines11010214
    Language: English
    Publisher: MDPI AG
    Publication Date: 2023
    detail.hit.zdb_id: 2720867-9
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  • 6
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    Application of Raman spectroscopy for detection of histologically distinct areas in formalin-fixed paraffin-embedded glioblastoma
    Oxford University Press (OUP) ; 2021
    In:  Neuro-Oncology Advances Vol. 3, No. 1 ( 2021-01-01)
    Details
    In: Neuro-Oncology Advances, Oxford University Press (OUP), Vol. 3, No. 1 ( 2021-01-01)
    Abstract: Although microscopic assessment is still the diagnostic gold standard in pathology, non-light microscopic methods such as new imaging methods and molecular pathology have considerably contributed to more precise diagnostics. As an upcoming method, Raman spectroscopy (RS) offers a “molecular fingerprint” that could be used to differentiate tissue heterogeneity or diagnostic entities. RS has been successfully applied on fresh and frozen tissue, however more aggressively, chemically treated tissue such as formalin-fixed, paraffin-embedded (FFPE) samples are challenging for RS. Methods To address this issue, we examined FFPE samples of morphologically highly heterogeneous glioblastoma (GBM) using RS in order to classify histologically defined GBM areas according to RS spectral properties. We have set up an SVM (support vector machine)-based classifier in a training cohort and corroborated our findings in a validation cohort. Results Our trained classifier identified distinct histological areas such as tumor core and necroses in GBM with an overall accuracy of 70.5% based on the spectral properties of RS. With an absolute misclassification of 21 out of 471 Raman measurements, our classifier has the property of precisely distinguishing between normal-appearing brain tissue and necrosis. When verifying the suitability of our classifier system in a second independent dataset, very little overlap between necrosis and normal-appearing brain tissue can be detected. Conclusion These findings show that histologically highly variable samples such as GBM can be reliably recognized by their spectral properties using RS. As conclusion, we propose that RS may serve useful as a future method in the pathological toolbox.
    Type of Medium: Online Resource
    ISSN: 2632-2498
    URL: Article
    DOI: 10.1093/noajnl/vdab077
    Language: English
    Publisher: Oxford University Press (OUP)
    Publication Date: 2021
    detail.hit.zdb_id: 3009682-0
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  • 7
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    Formulation of the critical lateral buckling moment of steel beams under asymmetric loadings
    Elsevier BV ; 2023
    In:  Thin-Walled Structures Vol. 182 ( 2023-01), p. 110163-
    Details
    In: Thin-Walled Structures, Elsevier BV, Vol. 182 ( 2023-01), p. 110163-
    Type of Medium: Online Resource
    ISSN: 0263-8231
    URL: Article
    DOI: 10.1016/j.tws.2022.110163
    Language: English
    Publisher: Elsevier BV
    Publication Date: 2023
    detail.hit.zdb_id: 2002844-1
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  • 8
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    Online Resource
    Association between Increased Bcl-2, Fas and FasL Levels and Inflammation Extent in Labial Salivary Glands During Primary Sjögren's Syndrome
    Bentham Science Publishers Ltd. ; 2022
    In:  Endocrine, Metabolic & Immune Disorders - Drug Targets Vol. 22, No. 3 ( 2022-03), p. 328-338
    Details
    In: Endocrine, Metabolic & Immune Disorders - Drug Targets, Bentham Science Publishers Ltd., Vol. 22, No. 3 ( 2022-03), p. 328-338
    Abstract: Primary Sjögren Syndrome (pSS) is a chronic autoimmune disease characterized by epithelial atrophy, mononuclear infiltration in exocrine glands resulting in the defective function of these glands. In pSS, atrophy of the epithelium is caused by an increased amount of apoptosis. Objective: The main aim of this study is to investigate the role of the apoptosis-related factors by studying Bcl-2, Fas and FasL expression in relation to the extent of inflammation as well as the effect of therapy on the expression of these mediators. Methods: In pSS patients (n=62) documented for their serological and clinical features, Fas, FasL and Bcl-2 plasma levels were assessed using enzyme-linked immunosorbent assays. In the same context, we investigated their expression by immunohistochemistry analysis in the labial salivary glands samples in association with the extent of inflammation. Results: Interestingly, our results indicated that in pSS patients, the plasmatic Bcl-2, Fas and FasL levels, which appeared to be associated with the severity of inflammation and were significantly elevated in comparison to the healthy controls. Moreover, a significant decrease in all these factors was observed in patients after combined corticosteroids-hydroxychloroquine therapy. Importantly, we report a strong positive correlation between Bcl-2 and NO levels. The immunohistochemical staining reveals a strong Bcl-2 expression in infiltrating mononuclear cells and a total absence in the acinar cells. The Bcl-2 level varies according to the severity of pathology. However, the expression of Fas and FasL was less important and predominantly localized in infiltrating mononuclear cells. Conclusion: Our current study highlights the involvement of Bcl-2, Fas and FasL in pSS glands injury. These factors may act as useful predictor markers of a clinical course in pSS, suggesting a novel approach in the pSS patients monitoring.
    Type of Medium: Online Resource
    ISSN: 1871-5303
    URL: Article
    DOI: 10.2174/1871530321666210809155147
    Language: English
    Publisher: Bentham Science Publishers Ltd.
    Publication Date: 2022
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  • 9
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    Mechanical Modeling and General Analytical Solution for the Dynamic Buckling of Plane Structures Using a Beam-Column Element with Varying End Restraints
    World Scientific Pub Co Pte Ltd ; 2022
    In:  International Journal of Structural Stability and Dynamics Vol. 22, No. 02 ( 2022-02)
    Details
    In: International Journal of Structural Stability and Dynamics, World Scientific Pub Co Pte Ltd, Vol. 22, No. 02 ( 2022-02)
    Abstract: The stability of structures is an important aspect that the designer must pay particular attention to in order to ensure safety against collapse. This investigation is concerned with analytical and numerical analyses of the dynamic buckling of plane structures. A rigorous mechanical model is proposed, consisting of a beam-column element with nodal ends possessing two rotational springs of rigidities acting in parallel with the bending stiffness of the beam-column. The model is first analyzed with respect to the dynamic behavior by investigating the influence of the variation in the stiffness of the nodal springs on the fundamental frequency of the proposed mechanical model. Compression axial loading is applied to the beam-column in order to study the nonlinear dynamic behavior by introducing buckling. This novel approach is used to highlight the interaction between the fundamental frequency and the critical buckling load. Simple examples are treated using the approach and the results are compared with those obtained from a global analysis. The results revealed that it is possible to reproduce the stability analysis of a global structure by simply analyzing a target element, taking into account all elements adjacent to it with less than 1% error on the results.
    Type of Medium: Online Resource
    ISSN: 0219-4554 , 1793-6764
    URL: Article
    DOI: 10.1142/S0219455422500195
    Language: English
    Publisher: World Scientific Pub Co Pte Ltd
    Publication Date: 2022
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  • 10
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    Intraoperative discrimination of native meningioma and dura mater by Raman spectroscopy
    Springer Science and Business Media LLC ; 2021
    In:  Scientific Reports Vol. 11, No. 1 ( 2021-12-08)
    Details
    In: Scientific Reports, Springer Science and Business Media LLC, Vol. 11, No. 1 ( 2021-12-08)
    Abstract: Meningiomas are among the most frequent tumors of the central nervous system. For a total resection, shown to decrease recurrences, it is paramount to reliably discriminate tumor tissue from normal dura mater intraoperatively. Raman spectroscopy (RS) is a non-destructive, label-free method for vibrational analysis of biochemical molecules. On the microscopic level, RS was already used to differentiate meningioma from dura mater. In this study we test its suitability for intraoperative macroscopic meningioma diagnostics. RS is applied to surgical specimen of intracranial meningiomas. The main purpose is the differentiation of tumor from normal dura mater, in order to potentially accelerate the diagnostic workflow. The collected meningioma and dura mater samples (n = 223 tissue samples from a total of 59 patients) are analyzed under untreated conditions using a new partially robotized RS acquisition system. Spectra (n = 1273) are combined with the according histopathological analysis for each sample. Based on this, a classifier is trained via machine learning. Our trained classifier separates meningioma and dura mater with a sensitivity of 96.06 $$\pm $$ ± 0.03% and a specificity of 95.44 $$\pm $$ ± 0.02% for internal fivefold cross validation and 100% and 93.97% if validated with an external test set. RS is an efficient method to discriminate meningioma from healthy dura mater in fresh tissue samples without additional processing or histopathological imaging. It is a quick and reliable complementary diagnostic tool to the neuropathological workflow and has potential for guided surgery. RS offers a safe way to examine unfixed surgical specimens in a perioperative setting.
    Type of Medium: Online Resource
    ISSN: 2045-2322
    URL: Article
    DOI: 10.1038/s41598-021-02977-7
    Language: English
    Publisher: Springer Science and Business Media LLC
    Publication Date: 2021
    detail.hit.zdb_id: 2615211-3
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