Bimodal Spectroscopy of Formalin Fixed Samples to Discriminate Dysplastic and Tumor Brain Tissues

Biomedical spectroscopy has gained attention in the past few years for disease diagnosis. Fluorescence and Raman spectroscopies provide finger-print information related to biochemical and morphological alterations when tissues progress from the normal to a malignant stage. Usually, freshly excised tissue specimens are preferred for bio-spectroscopic studies. However, ethical issues, sample availability and distance between the surgery room and the laboratory provide an impelling restriction for in-vitro spectroscopic studies using freshly excised samples. After surgical resection tissues are fixed in 4% formalin for histological studies under a light microscope. The process of fixation prevents degradation of tissues. In this study, we probe the use of formalin fixed sample for differentiating normal and dysplastic brain tissues using fluorescence and Raman spectroscopies. It was found that fluorescence spectral profile changes in the wavelength range from 550-750 nm between dysplastic and tumor samples. Also, significant differences were found in the Raman spectral profiles of such samples. The results indicate a potential diagnostic application of spectroscopy in formalin fixed brain samples for differentiating dysplastic and tumor brain tissues

Tracking azimuthons in nonlocal nonlinear media

We study the formation of azimuthons, i.e., rotating spatial solitons, in media with nonlocal focusing nonlinearity. We show that whole families of these solutions can be found by considering internal modes of classical non-rotating stationary solutions, namely vortex solitons. This offers an exhaustive method to identify azimuthons in a given nonlocal medium. We demonstrate formation of azimuthons of different vorticities and explain their properties by considering the strongly nonlocal limit of accessible solitons.Comment: 11 pages, 7 figure

Ultra-high-field targeted imaging of focal cortical dysplasia: The intracortical black line sign in type IIB

BACKGROUND AND PURPOSE: Conventional MR imaging has limitations in detecting focal cortical dysplasia. We assessed the added value of 7T in patients with histologically proved focal cortical dysplasia to highlight correlations between neuropathology and ultra-high-field imaging. MATERIALS AND METHODS: Between 2013 and 2019, we performed a standardized 7T MR imaging protocol in patients with drug-resistant focal epilepsy. We focused on 12 patients in whom postsurgical histopathology revealed focal cortical dysplasia and explored the diagnostic yield of preoperative 7T versus 1.5/3T MR imaging and the correlations of imaging findings with histopathology. We also assessed the relationship between epilepsy surgery outcome and the completeness of surgical removal of the MR imaging-visible structural abnormality. RESULTS: We observed clear abnormalities in 10/12 patients using 7T versus 9/12 revealed by 1.5/3T MR imaging. In patients with focal cortical dysplasia I, 7T MR imaging did not disclose morphologic abnormalities (n = 0/2). In patients with focal cortical dysplasia II, 7T uncovered morphologic signs that were not visible on clinical imaging in 1 patient with focal cortical dysplasia IIa (n = 1/4) and in all those with focal cortical dysplasia IIb (n = 6/6). T2*WI provided the highest added value, disclosing a peculiar intracortical hypointense band (black line) in 5/6 patients with focal cortical dysplasia IIb. The complete removal of the black line was associated with good postsurgical outcome (n = 4/5), while its incomplete removal yielded unsatisfactory results (n = 1/5). CONCLUSIONS: The high sensitivity of 7T T2*-weighted images provides an additional tool in defining potential morphologic markers of high epileptogenicity within the dysplastic tissue of focal cortical dysplasia IIb and will likely help to more precisely plan epilepsy surgery and explain surgical failures

Modulation analysis of boundary-induced motion of optical solitary waves in a nematic liquid crystal

We consider the motion of a solitary wave, a nematicon, in a finite cell filled with a nematic liquid crystal. A modulation theory is developed to describe the boundary-induced bouncing of a nematicon in a one-dimensional cell and it is found to give predictions in very good agreement with numerical solutions. The boundary-induced motion is then considered numerically for a two-dimensional cell and a simple extension of the modulation theory from one to two space dimensions is then made, with good agreement being found with numerical solutions for the nematicon trajectory. The role of nematicon shape and relative position to the boundaries in its evolution is discussed

Optical twists in phase and amplitude

Light beams with helical phase profile correspond to photons having orbital angular momentum (OAM). A Laguerre-Gaussian (LG) beam is an example where its helical phase sets a phase-singularity at the optical axis and forms a ring-shaped transverse amplitude profile. Here, we describe a unique beam where both phase and amplitude express a helical profile as the beam propagates in free space. Such a beam can be accurately referred to as an optical twister. We characterize optical twisters and demonstrate their capacity to induce spiral motion on particles trapped along the twisters' path. Unlike LG beams, the far field projection of the twisted optical beam maintains a high photon concentration even at higher values of topological charge. Optical twisters have therefore profound applications to fundamental studies of light and atoms such as in quantum entanglement of the OAM, toroidal traps for cold atoms and for optical manipulation of microscopic particles.V.R.D. has been funded partially by the Australian National University – Office of the Vice-Chancellor. D.P. and J.G. acknowledge financial support from the Danish Technical Scientific Research Council (FTP)

Angiocentric glioma-associated seizures: The possible role of EATT2, pyruvate carboxylase and glutamine synthetase

Purpose: Our purpose was to better understand the pathogenesis of seizures associated with angiocentric glioma. Angiocentric glioma is an indolent and rare low-grade glioma. Its typical clinical presentation is with epileptic seizures. The pathogenesis of tumor-associated seizures is poorly understood. Among the possible pathomechanisms, the increased neurotoxic concentrations of the glutamate has been proposed. Glutamate transporters, pyruvate carboxylase and glutamine synthetase are involved in maintaining the physiological concentration of glutamate in the inter synaptic spaces. Methods: We evaluated the immunohistochemical expression of EAAT2 (the most important glutamate transporter), pyruvate carboxylase and glutamine synthetase in 17 angiocentric gliomas. Results: EAAT2 was never expressed (0%) in the neoplastic cells in none of the cases studied. Pyruvate carboxylase was expressed in the cytoplasm of the neoplastic cells in 16/17 cases (94 %). Glutamine synthetase was expressed in the cytoplasm of the neoplastic cells in 15/17 cases (88 %). Conclusion: The net result of this enzymatic expression, in particular considering the loss of EAAT2, could be an increased glutamate concentration in the synaptic clef, which might increase local network excitability initially involving intratumoral neurons. The observation that the angiocentric glioma-associated epilepsy might be at least in part related to EAAT2 deficiency opens up interesting therapeutic perspectives

A Situational Alignment Framework for PACS

This paper reports the outcomes of a study on an integrated situational alignment framework for picture archiving and communication systems (PACS) labeled as PISA. Following the design research cycle, complementary validation methods and pilot cases were used to assess the proposed framework and its operationalized survey. In this paper, the authors outline (a) the process of the framework’ development, (b) the validation process with its underlying iterative steps, (c) the outcomes of pilot cases, and (d) improvement opportunities to refine and further validate the PISA framework. Results of this study support empirical application of the framework to hospital enterprises in order to gain insights into their PACS maturity and alignment. We argue that the framework can be applied as a valuable tool for assessments, monitoring and benchmarking purposes and strategic PACS planning

Trends in pediatric epilepsy surgery in Europe between 2008 and 2015: Country‐, center‐, and age‐specific variation

OBJECTIVE: To profile European trends in pediatric epilepsy surgery (<16 years of age) between 2008 and 2015. METHODS: We collected information on volumes and types of surgery, pathology, and seizure outcome from 20 recognized epilepsy surgery reference centers in 10 European countries. RESULTS: We analyzed retrospective aggregate data on 1859 operations. The proportion of surgeries significantly increased over time (P < .0001). Engel class I outcome was achieved in 69.3% of children, with no significant improvement between 2008 and 2015. The proportion of histopathological findings consistent with glial scars significantly increased between the ages of 7 and 16 years (P for trend = .0033), whereas that of the remaining pathologies did not vary across ages. A significant increase in unilobar extratemporal surgeries (P for trend = .0047) and a significant decrease in unilobar temporal surgeries (P for trend = .0030) were observed between 2008 and 2015. Conversely, the proportion of multilobar surgeries and unrevealing magnetic resonance imaging cases remained unchanged. Invasive investigations significantly increased, especially stereo‐electroencephalography. We found different trends comparing centers starting their activity in the 1990s to those whose programs were developed in the past decade. Multivariate analysis revealed a significant variability of the proportion of the different pathologies and surgical approaches across countries, centers, and age groups between 2008 and 2015. SIGNIFICANCE: Between 2008 and 2015, we observed a significant increase in the volume of pediatric epilepsy surgeries, stability in the proportion of Engel class I outcomes, and a modest increment in complexity of the procedures