Crystal Structure of Bombyx mori Lipoprotein 6: Comparative Structural Analysis of the 30-kDa Lipoprotein Family

The 30-kDa lipoprotein (LP) family of mulberry silkworm comprises major hemolymph proteins specific to the fifth instar larvae. The family consists of 46 members, 24 of which are referred to as typical 30-kDa LPs. To date, two crystal structures of 30-kDa LPs from Bombyx mori have been described (Bmlp3 and Bmlp7). Here, we present the crystal structure of Bmlp6, another 30-kDa LP member. Bmlp6 is comprised of two domains characteristic of this family, the VHS-type N-terminal domain and b-trefoil C-terminal domain. The structures of the three 30-kDa LPs have been compared and a number of differences are noted, including loop conformation, the surface electrostatic potential, and the potential binding cavities. We discuss the observed structural differences in the light of the potential different roles of the particular 30-kDa LP members in silkworm physiology

Faraday Rotation Spectroscopy of Quantum-Dot Quantum Wells

Time-resolved Faraday rotation studies of CdS/CdSe/CdS quantum-dot quantum wells have recently shown that the Faraday rotation angle exhibits several well-defined resonances as a function of probe energy close to the absorption edge. Here, we calculate the Faraday rotation angle from the eigenstates of the quantum-dot quantum well obtained with k.p theory. We show that the large number of narrow resonances with comparable spectral weight observed in experiment is not reproduced by the level scheme of a quantum-dot quantum well with perfect spherical symmetry. A simple model for broken spherical symmetry yields results in better qualitative agreement with experiment.Comment: 9 pages, 4 figure

Isoprostanes as potential cerebral vasospasm biomarkers

Despite enormous progress in medicine, symptomatic cerebral vasospasm (CVS), remains an unexplained clinical problem, which leaves both physicians and patients helpless and relying on chance, due to the lack of specific marker indicative of imminent danger as well as the lack of specific treatment. In our opinion CVS occurrence depends on dynamic disbalance between free radicals' formation (oxidative stress) and antioxidant activity. Isoprostanes are products of free-radical peroxidation of polyunsaturated fatty acids, and seem to mark a promising path for the research aiming to unravel its possible mechanism. Not only are they the biomarkers of oxidative stress in vivo and in vitro, but also have manifold biological effects (including vasoactive, inflammatory and mitogenic) via activation of the thromboxane A2 receptor (TBXA2R), both in physiological and pathophysiological processes. This review addresses the importance of isoprostanes in CVS in quest of appropriate biomarkers

Reorganization of language centers in patients with brain tumors located in eloquent speech areas – A pre- and postoperative preliminary fMRI study

Introduction The aim of this study was to determine in pre- and postsurgical fMRI studies the rearrangement of the Broca's and Wernicke's areas and the lateralization index for these areas in patients with brain tumors located near speech centers. Impact of the surgical treatment on the brain plasticity was evaluated. Materials and methods Pre- and postoperative fMRI examinations were performed in 10 patients with low grade glial, left-sided brain tumors located close to the Broca's (5 patients) or Wernicke's area (5 patients). BOLD signal was recorded in regions of interest: Broca's and Wernicke's areas, and their anatomic right-sided homologues. Results In the preoperative fMRI study the left Broca's area was activated in all cases. The right Broca's area was activated in all the patients with no speech disorders. In the postoperative fMRI the activation of both Broca's areas increased in two cases. In other two cases activation of one of the Broca's area increased along with the decrease in the contralateral hemisphere. In all patients with temporal lobe tumors, the right Wernicke's area was activated in the pre- and postsurgical fMRI. After the operation, in two patients with speech disorder, the activation of both Broca's areas decreased and the activation of one of the Wernicke's areas increased. Conclusions In the cases of tumors localized near the left Broca's area, a transfer of the function to the healthy hemisphere seems to take place. Resection of tumors located near Broca's or Wernicke's areas may lead to relocation of the brain language centers

Spektroskopia rezonansu magnetycznego w wewnątrzczaszkowych nowotworach pochodzenia glejowego

Background and purpose To determine in vivo magnetic resonance spectroscopy (MRS) characteristics of intracranial glial tumours and to assess MRS reliability in glioma grading and discrimination between different histopathological types of tumours. Material and methods Analysis of spectra of 26 patients with glioblastomas, 6 with fibrillary astrocytomas, 4 with anaplastic astrocytomas, 2 with pilocytic astrocytoma, 3 with oligodendrogliomas, 3 with anaplastic oligodendrogliomas and 17 control spectra taken from healthy hemispheres. Results All tumours’ metabolite ratios, except for Cho/Cr in fibrillary astrocytomas (p = 0.06), were statistically signiflcantly different from the control. The tumours showed decreased Naa and Cr contents and a high Cho signal. The Lac-Lip signal was high in grade III astrocytomas and glioblastomas. Reports that Cho/Cr ratio increases with glioma's grade whereas Naa/Cr decreases were not confirmed. Anaplastic astrocytomas compared to grade II astrocytomas had a statistically significantly greater ml/Cr ratio (p = 0.02). In pilocytic astrocytomas the Naa/Cr value (2.58 ± 0.39) was greater, whilst the Cho/Naa ratio was lower (2.14 ± 0.64) than in the other astrocytomas. The specific feature of oligodendrogliomas was the presence of glutamate/glutamine peak Glx. However, this peak was absent in two out of three anaplastic oligodendrogliomas. Characteristically, the latter tumours had a high Lac-Lip signal. Conclusions MRS in vivo cannot be used as a reliable method for glioma grading. The method is useful in discrimination between WHO grade I and WHO grade II astrocytomas as well as oligodendrogliomas from other gliomas.Wstęp i cel pracy Ustalenie charakterystyki spektroskopii magnetycznego rezonansu jądrowego (magnetic resonance spectroscopy – MRS) u chorych z nowotworami wewnątrzczaszkowymi pochodzenia glejowego oraz ocena przydatności tego badania w diagnostyce różnicowej typów histologicznych glejaków. Materiał i metody Przeprowadzono analizę widm MRS nowotworów u 26 chorych z glejakami wielopostaciowymi, 6 z gwiaździakami włókienkowymi, 4 z gwiaździakami anaplastycznymi, 2 z włosowatokomórkowymi, 3 ze skąpodrzewiakami, 3 ze skąpodrzewiakami anaplastycznymi oraz 17 widm kontrolnych pochodzących ze zdrowych półkul mózgu. Wyniki Wszystkie wskaźniki metaboliczne w przypadkach nowotworów, z wyjątkiem Cho/Cr w gwiaździakach włókienkowych (p = 0,06), różniły się znamiennie od tych w grupie kontrolnej. Nowotwory wykazywały zmniejszoną zawartość Naa i Cr oraz wysoki sygnał Cho. Sygnał Lac-Lip był wysoki w gwiaździakach III stopnia wg WHO i glejakach wielopostaciowych. Nie udało się potwierdzić doniesień, że wskaźnik Cho/Cr rośnie, a wskaźnik Naa/Cr maleje wraz ze wzrostem stopnia złośliwości glejaka. Gwiaździaki anaplastyczne wykazywały znamiennie wyższy wskaźnik ml/Cr (p = 0,02) w porównaniu z gwiaździakami II stopnia wg WHO. W gwiaździakach włosowatokomórkowych wartość Naa/Cr (2,58 ± 0,39) była większa, a Cho/Naa mniejsza (2,14 ± 0,64) niż w innych gwiaździakach. Skąpodrzewiaki charakteryzowała obecność szczytu glutaminianu/glutaminy (Glx), którego jednak nie obserwowano w 2 spośród 3 przypadków skąpodrzewiaków anaplastycznych. Dla tych ostatnich symptomatyczna była obecność silnego sygnału Lac-Lip. Wnioski Badanie MRS in vivo nie jest niezawodną metodą różnicującą glejaki wewnątrzczaszkowe. Wydaje się użyteczne w diagnostyce różnicowej gwiaździaków I i II stopnia wg WHO oraz w odróżnianiu skąpodrzewiaków od pozostałych glejaków

Ciśnienie śródczaszkowe a mózgowy przepływ krwi

Ciśnienie śródczaszkowe i mózgowy przepływ krwi to jedne z podstawowych pojęć neurofizjologicznych. Znajomość związanych z nimi zagadnień jest warunkiem zrozumienia ważnych procesów patologicznych zachodzących w ośrodkowym układzie nerwowym. W pracy omówiono fizjologię i patofizjologię ciśnienia śródczaszkowego, przepływu mózgowego oraz ich wzajemne relacje, w tym koncepcję krytycznego ciśnienia zamykającego naczynia mózgowe

Multiband theory of quantum-dot quantum wells: Dark excitons, bright excitons, and charge separation in heteronanostructures

Electron, hole, and exciton states of multishell CdS/HgS/CdS quantum-dot quantum well nanocrystals are determined by use of a multiband theory that includes valence-band mixing, modeled with a 6-band Luttinger-Kohn Hamiltonian, and nonparabolicity of the conduction band. The multiband theory correctly describes the recently observed dark-exciton ground state and the lowest, optically active, bright-exciton states. Charge separation in pair states is identified. Previous single-band theories could not describe these states or account for charge separation.Comment: 10 pages of ReVTex, 6 ps figures, submitted to Phys. Rev.

Recursion representation of the Neveu-Schwarz superconformal block

Four-point super-conformal blocks for the N = 1 Neveu-Schwarz algebra are defined in terms of power series of the even super-projective invariant. Coefficients of these expansions are represented both as sums over poles in the "intermediate" conformal weight and as sums over poles in the central charge of the algebra. The residua of these poles are calculated in both cases. Closed recurrence relations for the block coefficients are derived.Comment: 20 page

Automated volumetric evaluation of intracranial compartments and cerebrospinal fluid distribution on emergency trauma head CT scans to quantify mass effect

BackgroundIntracranial space is divided into three compartments by the falx cerebri and tentorium cerebelli. We assessed whether cerebrospinal fluid (CSF) distribution evaluated by a specifically developed deep-learning neural network (DLNN) could assist in quantifying mass effect.MethodsHead trauma CT scans from a high-volume emergency department between 2018 and 2020 were retrospectively analyzed. Manual segmentations of intracranial compartments and CSF served as the ground truth to develop a DLNN model to automate the segmentation process. Dice Similarity Coefficient (DSC) was used to evaluate the segmentation performance. Supratentorial CSF Ratio was calculated by dividing the volume of CSF on the side with reduced CSF reserve by the volume of CSF on the opposite side.ResultsTwo hundred and seventy-four patients (mean age, 61 years ± 18.6) after traumatic brain injury (TBI) who had an emergency head CT scan were included. The average DSC for training and validation datasets were respectively: 0.782 and 0.765. Lower DSC were observed in the segmentation of CSF, respectively 0.589, 0.615, and 0.572 for the right supratentorial, left supratentorial, and infratentorial CSF regions in the training dataset, and slightly lower values in the validation dataset, respectively 0.567, 0.574, and 0.556. Twenty-two patients (8%) had midline shift exceeding 5 mm, and 24 (8.8%) presented with high/mixed density lesion exceeding >25 ml. Fifty-five patients (20.1%) exhibited mass effect requiring neurosurgical treatment. They had lower supratentorial CSF volume and lower Supratentorial CSF Ratio (both p < 0.001). A Supratentorial CSF Ratio below 60% had a sensitivity of 74.5% and specificity of 87.7% (AUC 0.88, 95%CI 0.82–0.94) in identifying patients that require neurosurgical treatment for mass effect. On the other hand, patients with CSF constituting 10–20% of the intracranial space, with 80–90% of CSF specifically in the supratentorial compartment, and whose Supratentorial CSF Ratio exceeded 80% had minimal risk.ConclusionCSF distribution may be presented as quantifiable ratios that help to predict surgery in patients after TBI. Automated segmentation of intracranial compartments using the DLNN model demonstrates a potential of artificial intelligence in quantifying mass effect. Further validation of the described method is necessary to confirm its efficacy in triaging patients and identifying those who require neurosurgical treatment

Electronic structure and optical properties of ZnS/CdS nanoheterostructures

The electronic and optical properties of spherical nanoheterostructures are studied within the semi-empirical $sp^{3}s^{*}$ tight-binding model including the spin-orbit interaction. We use a symmetry-based approach previously applied to CdSe and CdTe quantum dots. The complete one-particle spectrum is obtained by using group-theoretical methods. The excitonic eigenstates are then deduced in the configuration-interaction approach by fully taking into account the Coulomb direct and exchange interactions. Here we focus on ZnS/CdS, ZnS/CdS/ZnS and CdS/ZnS nanocrystals with particular emphasis on recently reported experimental data. The degree of carrier localization in the CdS well layer is analyzed as a function of its thickness. We compute the excitonic fine structure, i.e., the relative intensities of low-energy optical transitions. The calculated values of the absorption gap show a good agreement with the experimental ones. Enhanced resonant photoluminescence Stokes shifts are predicted.Comment: 6 pages, 4 Figures, revtex