Effects of formalin fixation on polarimetric properties of brain tissue: fresh or fixed?

Imaging Mueller polarimetry (IMP) appears as a promising technique for real-time delineation of healthy and neoplastic tissue during neurosurgery. The training of machine learning algorithms used for the image post-processing requires large data sets typically derived from the measurements of formalin-fixed brain sections. However, the success of the transfer of such algorithms from fixed to fresh brain tissue depends on the degree of alterations of polarimetric properties induced by formalin fixation (FF). Comprehensive studies were performed on the FF induced changes in fresh pig brain tissue polarimetric properties. Polarimetric properties of pig brain were assessed in 30 coronal thick sections before and after FF using a wide-field IMP system. The width of the uncertainty region between gray and white matter was also estimated. The depolarization increased by 5% in gray matter and remained constant in white matter following FF, whereas the linear retardance decreased by 27% in gray matter and by 28% in white matter after FF. The visual contrast between gray and white matter and fiber tracking remained preserved after FF. Tissue shrinkage induced by FF did not have a significant effect on the uncertainty region width. Similar polarimetric properties were observed in both fresh and fixed brain tissues, indicating a high potential for transfer learning

Socio-economic gaps in educational aspirations: do experiences and attitudes matter?

We use detailed survey data linked to administrative records from secondary schools in England to investigate potential channels contributing to the socio-economic gap in post-compulsory educational aspirations. We investigate the role of experiences and attitudes including the provision of information, advice and guidance (IAG), bullying victimisation, locus of control and self-perception of academic potential. Our findings indicate a significant socio-economic gap in aspirations to stay in education, to follow the academic rather than the vocational route, and to attend university. We use decomposition analysis to show that the experiences we consider are not statistically correlated with the observed socio-economic gap while differences in attitudes explain up to 22% of the effect. The findings suggest that investing in self-esteem building and attribution training programmes within schools could contribute to equalising educational outcomes

[Myositis as a post-acute sequela of COVID-19 disease? : Even in times of the pandemic, muscle biopsies can only be assessed in the context of accurate clinical information].

A case of a patient suffering from COVID-19 with suspected associated myositis is reported, in which the initially limited information about the history and disease course led to difficulties in establishing a reasonable diagnosis. Through inquiry, further data could be collected, so that the diagnosis of an infection-associated thrombotic microangiopathy in the context of a Morganella morganii myositis could be made. This patient study shows that even in times of the omnipresent pandemic and despite the context of a positive COVID-19 test result, differential diagnoses and the integrative clinicopathologic approach in interpreting muscle biopsy findings should not be neglected

Langerhans cell histiocytosis mimicking aggressive periodontitis: Challenges in diagnosis and management

Objective: Langerhans cell histiocytosis (LCH) is a rare disorder characterized by clonal proliferation of Langerhans cells that affects various organs. Oral involvement may simulate periodontal disease and cause significant diagnostic and management difficulties. Here, we present an interesting LCH case with severe periodontal destruction in a young woman in order to facilitate early recognition of this aggressive disease and successful participation of the general practitioner in the management of such patients. Case Presentation: A 21-year-old woman was referred for evaluation of recurrent episodes of dull pain in the gingiva for the last 9 months, which had not been successfully managed by her general practitioner. Clinical and radiographic examination showed extensive alveolar bone loss. Histopathologic examination revealed diffuse aggregates of Langerhans cells, while a complete workup did not demonstrate evidence of systemic involvement. A diagnosis of LCH limited to the oral cavity was established. The patient received systemic chemotherapy in combination with appropriate dental care including gingival debridement and tooth immobilization. Following chemotherapy completion, comparative clinical, radiographic, and microscopic evaluation showed complete remission. During an 18-month follow-up period, frequent oral examinations and appropriate dental interventions confirmed the lack of LCH recurrence and guaranteed the stabilization of periodontal tissues. Conclusions: Oral soft and hard tissue involvement may be the only manifestation of LCH. The present case exemplifies the importance of close collaboration between general dentistry and its disciplines (periodontology, restorative dentistry, oral medicine, oral and maxillofacial pathology, and oral radiology), and hematology-oncology for diagnosis, management, treatment monitoring, and decision-making. © Quintessence. All rights reserved

Longitudinal optical phonon assisted polariton laser

We demonstrate the role of longitudinal optical (LO)-phonon assisted polariton relaxation in reducing the stimulation threshold in strongly coupled microcavities. When the energy of the relaxation bottleneck is one LO-phonon above the ground polariton state, we observe a tenfold improvement of the polariton relaxation rate in the linear regime, and a twofold reduction in the threshold to the nonlinear polariton lasing regime.Microcavity polaritons are quasibosons that result from the strong-coupling of cavity photons and excitons confined in a single nanostructure.1 Their bosonic nature gives rise to a plethora of nonlinear phenomena2,3 epitomized by the quantum phase transition to nonequilibrium Bose–Einstein condensation.4–6 The lifetime of polariton condensates is limited to the cavity-photon lifetime leading to the radiation of directional, coherent light, termed polariton laser.7 Unlike conventional lasers, polariton lasers do not require population inversion and have the potential to operate with reduced thresholds. To date, polariton lasers have only been realized under optical excitation in microcavities with GaAs,8 CdTe,9 and GaN (Ref. 10) active material. Although electrical pumping in polariton light emitting diodes was achieved both in inorganic and organic microcavities,11–13 polariton lasing remains elusive under electrical carrier injection. As with nonresonant optical excitation schemes, so with electrical injection relaxation bottleneck leads to substantial homogeneous broadening and loss of strong coupling in the linear regime

Optical analogue of the spin Hall effect in a photonic cavity

We observe anisotropy in the polarization flux generated in a GaAs/AlAs photonic cavity by optical illumination, equivalent to spin currents in strongly coupled microcavities. Polarization rotation of the scattered photons around the Rayleigh ring is due to the TE–TM splitting of the cavity mode. Resolving the circular polarization components of the transmission reveals a separation of the polarization flux in momentum space. These observations constitute the optical analogue of the spin Hall effect

Integrated longitudinal analysis of adult grade 4 diffuse gliomas with long-term relapse interval revealed upregulation of TGF-β signaling in recurrent tumors.

Adult-type diffuse gliomas, CNS WHO grade 4 are the most aggressive primary brain tumors and represent a particular challenge of therapeutic intervention. In a single-center retrospective study of matched pairs of initial and post-therapeutic glioma cases with a recurrence period greater than one year, we performed whole exome sequencing combined with mRNA and microRNA expression profiling to identify processes that are altered in recurrent gliomas. Mutational analysis of recurrent gliomas revealed early branching evolution in seventy-five percent of patients. High plasticity was confirmed at the mRNA and miRNA levels. SBS1 signature was reduced and SBS11 was elevated, demonstrating the effect of alkylating agent therapy on the mutational landscape. There was no evidence for secondary genomic alterations driving therapy resistance. ALK7/ACVR1C and LTBP1 were upregulated, whereas LEFTY2 was downregulated, pointing towards enhanced Tumor Growth Factor β (TGF-β) signaling in recurrent gliomas. Consistently, altered microRNA expression profiles pointed towards enhanced Nuclear Factor Kappa B and Wnt signaling that, cooperatively with TGF-β, induces epithelial to mesenchymal transition (EMT), migration and stemness. TGF-β-induced expression of pro-apoptotic proteins and repression of anti-apoptotic proteins were uncoupled in the recurrent tumor. Our results suggest an important role of TGF-β signaling in recurrent gliomas. This may have clinical implication, since TGF-β inhibitors have entered clinical phase studies and may potentially be used in combination therapy to interfere with chemoradiation resistance. Recurrent gliomas show high incidence of early branching evolution. High tumor plasticity is confirmed at the level of microRNA and mRNA expression profiles

Intraoperative in vivo confocal laser endomicroscopy imaging at glioma margins: can we detect tumor infiltration?

Confocal laser endomicroscopy (CLE) is a US Food and Drug Administration-cleared intraoperative real-time fluorescence-based cellular resolution imaging technology that has been shown to image brain tumor histoarchitecture rapidly in vivo during neuro-oncological surgical procedures. An important goal for successful intraoperative implementation is in vivo use at the margins of infiltrating gliomas. However, CLE use at glioma margins has not been well studied. Matching in vivo CLE images and tissue biopsies acquired at glioma margin regions of interest (ROIs) were collected from 2 institutions. All images were reviewed by 4 neuropathologists experienced in CLE. A scoring system based on the pathological features was implemented to score CLE and H&E images from each ROI on a scale from 0 to 5. Based on the H&E scores, all ROIs were divided into a low tumor probability (LTP) group (scores 0-2) and a high tumor probability (HTP) group (scores 3-5). The concordance between CLE and H&E scores regarding tumor probability was determined. The intraclass correlation coefficient (ICC) and diagnostic performance were calculated. Fifty-six glioma margin ROIs were included for analysis. Interrater reliability of the scoring system was excellent when used for H&E images (ICC [95% CI] 0.91 [0.86-0.94]) and moderate when used for CLE images (ICC [95% CI] 0.69 [0.40-0.83]). The ICCs (95% CIs) of the LTP group (0.68 [0.40-0.83]) and HTP group (0.68 [0.39-0.83]) did not differ significantly. The concordance between CLE and H&E scores was 61.6%. The sensitivity and specificity values of the scoring system were 79% and 37%. The positive predictive value (PPV) and negative predictive value were 65% and 53%, respectively. Concordance, sensitivity, and PPV were greater in the HTP group than in the LTP group. Specificity was higher in the newly diagnosed group than in the recurrent group. CLE may detect tumor infiltration at glioma margins. However, it is not currently dependable, especially in scenarios where low probability of tumor infiltration is expected. The proposed scoring system has excellent intrinsic interrater reliability, but its interrater reliability is only moderate when used with CLE images. These results suggest that this technology requires further exploration as a method for consistent actionable intraoperative guidance with high dependability across the range of tumor margin scenarios. Specific-binding and/or tumor-specific fluorophores, a CLE image atlas, and a consensus guideline for image interpretation may help with the translational utility of CLE