bluuebunny/crossref_metadata_2025_split huggingface dataset:
Progress and challenges of implantable neural interfaces based on nature-derived materials
Authors: Redolfi Riva Eugenio , Micera Silvestro 
Published: April 2021

AbstractNeural interfaces are bioelectronic devices capable of stimulating a population of neurons or nerve fascicles and recording electrical signals in a specific area. Despite their success in restoring sensory-motor functions in people with disabilities, their long-term exploitation is still limited by poor biocompatibility, mechanical mismatch between the device and neural tissue and the risk of a chronic inflammatory response upon implantation.In this context, the use of nature-derived materials can help address these issues. Examples of these materials, such as extracellular matrix proteins, peptides, lipids and polysaccharides, have been employed for decades in biomedical science. Their excellent biocompatibility, biodegradability in the absence of toxic compound release, physiochemical properties that are similar to those of human tissues and reduced immunogenicity make them outstanding candidates to improve neural interface biocompatibility and long-term implantation safety. The objective of this review is to highlight progress and challenges concerning the impact of nature-derived materials on neural interface design. The use of these materials as biocompatible coatings and as building blocks of insulation materials for use in implantable neural interfaces is discussed. Moreover, future perspectives are presented to show the increasingly important uses of these materials for neural interface fabrication and their possible use for other applications in the framework of neural engineering.
National Marrow Donor Program–Sponsored Multicenter, Phase II Trial of HLA-Mismatched Unrelated Donor Bone Marrow Transplantation Using Post-Transplant Cyclophosphamide
Authors: Shaw Bronwen E. , Jimenez-Jimenez Antonio Martin , Burns Linda J. , Logan Brent R. , Khimani Farhad , Shaffer Brian C. , Shah Nirav N. , Mussetter Alisha , Tang Xiao-Ying , McCarty John M. , Alavi Asif , Farhadfar Nosha , Jamieson Katarzyna , Hardy Nancy M. , Choe Hannah , Ambinder Richard F. , Anasetti Claudio , Perales Miguel-Angel , Spellman Stephen R. , Howard Alan , Komanduri Krishna V. , Luznik Leo , Norkin Maxim , Pidala Joseph A. , Ratanatharathorn Voravit , Confer Dennis L. , Devine Steven M. , Horowitz Mary M. , Bolaños-Meade Javier 
Published: April 2021

PURPOSEHematopoietic cell transplantation (HCT) is curative for hematologic disorders, but outcomes are historically inferior when using HLA-mismatched donors. Despite unrelated donor registries listing > 38 million volunteers, 25%-80% of US patients lack an HLA-matched unrelated donor, with significant disparity across ethnic groups. We hypothesized that HCT with a mismatched unrelated donor (MMUD) using post-transplant cyclophosphamide (PTCy), a novel strategy successful in overcoming genetic disparity using mismatched related donors, would be feasible and increase access to HCT.PATIENTS AND METHODSWe performed a prospective phase II study of MMUD bone marrow HCT with PTCy for patients with hematologic malignancies. The primary end point was 1-year overall survival (OS), hypothesized to be 65% or better. 80 patients enrolled at 11 US transplant centers (December 2016-March 2019). Following myeloablative or reduced-intensity conditioning–based HCT, patients received PTCy on days +3, +4, with sirolimus and mycophenolate mofetil starting on day +5. We compared outcomes to Center for International Blood and Marrow Transplant Research contemporary controls receiving PTCy.RESULTSNotably, 48% of patients enrolled were ethnic minorities. 39% of pairs were matched for 4-6 out of 8 HLA alleles. The primary end point was met, with 1-year OS of 76% (90% CI, 67.3 to 83.3) in the entire cohort, and 72% and 79% in the myeloablative and reduced-intensity conditioning strata, respectively. Secondary end points related to engraftment and graft-versus-host-disease were reached. Multivariate analysis comparing the study group with other mismatched HCT controls found no significant differences in OS.CONCLUSIONOur prospective study demonstrates the feasibility and effectiveness of HCT with an MMUD in the setting of PTCy. Remarkably, nearly half of the study participants belonged to an ethnic minority population, suggesting this approach may significantly expand access to HCT.
The Changing Inhibition of Early Differentiation and General Development in the Chick Embryo by 2 -Ethyl-5 -Methyl-Benzimidazole and Chloramphenicol
Authors: Blackwood Unabelle Boggs 
Published: April 2021

ABSTRACT
Studies conducted during the past 10 to 15 years primarily in amphibian and chick embryos have led to a controversy over the identity of substances principally responsible for induction and early differentiation. That ribonucleoproteins are most directly involved is widely accepted. However, the question of which is most important ribonucleic acid (RNA) or protein has been the major point of disagreement. Brachet (1950) first suggested that RNA plays the primary role in induction and early differentiation. Several investigators studying the inductive properties of denatured ribonucleoprotein preparations from mammalian organs on amphibian gastrula ectoderm have concluded that protein is of greater importance than RNA (reviews, Barth, 1957; Yamada, 1958). Work with non-denatured thymus preparations led Niu (1958) to report that protein plays a role in differentiation but that RNA is the causal agent.
β-catenin signaling can initiate feather bud development
Authors: Noramly Selina , Freeman Allison , Morgan Bruce A. 
Published: April 2021

Abstract
Intercellular signaling by a subset of Wnts is mediated by stabilization of cytoplasmic β-catenin and its translocation to the nucleus. Immunolocalization of β-catenin in developing chick skin reveals that this signaling pathway is active in a dynamic pattern from the earliest stages of feather bud development. Forced activation of this pathway by expression of a stabilized β-catenin in the ectoderm results in the ectopic formation of feather buds. This construct is sufficient to induce bud formation since it does so both within presumptive feather tracts and in normally featherless regions where tract-specific signals are absent. It is also insensitive to the lateral inhibition that mediates the normal spacing of buds and can induce ectopic buds in interfollicular skin. However, additional patterning signals cooperate with this pathway to regulate gene expression within domains of stabilized β-catenin expression. Localized activation of this pathway within the bud as it develops is required for normal morphogenesis and ectopic activation of the pathway leads to abnormally oriented buds and growths on the feather filaments. These results suggest that activation of the β-catenin pathway initiates follicle development in embryonic skin and plays important roles in the subsequent morphogenesis of the bud.
Anterior cephalic neural crest is required for forebrain viability
Authors: Etchevers Heather C. , Couly Gérard , Vincent Christine , Douarin Nicole M. Le 
Published: April 2021

Abstract
The prosencephalon, or embryonic forebrain, grows within a mesenchymal matrix of local paraxial mesoderm and of neural crest cells (NCC) derived from the posterior diencephalon and mesencephalon. Part of this NCC population forms the outer wall of capillaries within the prosencephalic leptomeninges and neuroepithelium itself. The surgical removal of NCC from the anterior head of chick embryos leads to massive cell death within the forebrain neuroepithelium during an interval that precedes its vascularization by at least 36 hours. During this critical period, a mesenchymal layer made up of intermingled mesodermal cells and NCC surround the neuroepithelium. This layer is not formed after anterior cephalic NCC ablation. The neuroepithelium then undergoes massive apoptosis. Cyclopia ensues after forebrain deterioration and absence of intervening frontonasal bud derivatives. The deleterious effect of ablation of the anterior NC cannot be interpreted as a deficit in vascularization because it takes place well before the time when blood vessels start to invade the neuroepithelium. Thus the mesenchymal layer itself exerts a trophic effect on the prosencephalic neuroepithelium. In an assay to rescue the operated phenotype, we found that the rhombencephalic but not the truncal NC can successfully replace the diencephalic and mesencephalic NC. Moreover, any region of the paraxial cephalic mesoderm can replace NCC in their dual function: in their early trophic effect and in providing pericytes to the forebrain meningeal blood vessels. The assumption of these roles by the cephalic neural crest may have been instrumental in the rostral expansion of the vertebrate forebrain over the course of evolution.
Effects of heat shock and cycloheximide on growth and division of the fission yeast,Schizosaccharomyces pombe
Authors: Polanshek Mark M. 
Published: April 2021

ABSTRACTEffects of superoptimal temperature shock (HS) and the protein synthesis inhibitor, cycloheximide (CH), on growth and division of the fission yeast, Schizosaccharomyces pombe, were studied. Experiments on asynchronous cultures have shown that a 15-min HS of 41 °C inhibits RNA and protein synthesis and growth in cell length while delaying mitosis, division, and DNA synthesis. A 10-min CH pulse (100 μg/ml) inhibits protein and RNA synthesis briefly while delaying mitosis, division, and DNA synthesis. These single heat or CH pulses partially synchronize mitosis, division, and DNA synthesis.Experiments in which either 15-min HS or 10-min CH pulses were applied at different times in selection-synchronized cultures have demonstrated several kinds and periods of sensitivity to these agents. During roughly the first two-thirds of the cell cycle (measured between divisions) mitosis, division, and DNA synthesis are delayed equally, delay increasing as a pulse is applied progressively later in the cycle. The magnitude of the delay from a heat shock is always greater than that from a CH pulse, but for both agents there is a period during which delay is greater in magnitude than pulse length. The pattern of delay from cultures synchronized by an induction method suggests that the period of increasing delay lies obligately within G2.At 0 ·65 in the cycle the nature of the sensitivity to heat and CH changes. Between this transition point and the formation of a cell plate, CH has no effects on the timing of mitosis or cell plate stage. However, CH can block the final splitting of the cell plate, leading to a permanent cell plate and the formation of transient 4-celled pseudo-filaments upon resumed growth. HS following the transition point allows mitosis to be completed with normal timing to a stage in which daughter nuclei occupy terminal positions in the cell, but formation of the cell plate is delayed by about 30 min. Cells pulsed in the last third of the cycle may develop several morphological aberrations. The cell plate is sometimes oblique or positioned at one end of the cell, giving rise to daughter cells with 2 or no nuclei. Thus, it appears that some functions related to normal positioning of the cell plate occur during the last third of the cycle.Recovery from a heat shock applied prior to 0 ·65 in the cycle includes a period in which there is increasing delay when a CH pulse is applied progressively later following the heat shock. However, applied together, CH plus HS produce roughly the amount of delay due to the HS alone. These facts are considered evidence for a common effect of both agents during the first two-thirds of the cycle.The results are discussed with reference to possible controls over several events of the cell cycle.
Junctional structures in Hydra
Authors: Filshie B.K. , Flower N. E. 
Published: April 2021

ABSTRACT
The sealing and communicating junctions present in hydra have been examined using conventional staining, lanthanum tracer and freeze-fracturing techniques. The presence of distinct types of gap and septate junctions has been confirmed. Combined lanthanum tracer and freezefracture results have provided a more detailed understanding of these junctional structures. A model has been constructed which demonstrates the various aspects of the junction seen at different sectioning angles.
The probable lengths of septa within septate junctions and the junctional ‘maze’ formed by them is discussed because of its bearing on the ‘sealing’ nature of the junction and also, to some extent, on its permeability to tracers such as lanthanum.
Plasma membrane intramembranous particle topography in 3t3 and sv3t3 cells: The effect of cytochalasin b
Authors: Scott Robert E. , Maercklein Peter B. , Furcht Leo T. 
Published: April 2021

ABSTRACT
The topography of plasma membrane intramembranous particles in contact-inhibited and transformed cells is a topic of current controversy. We have reported that particles are aggregated in 3T3 cells and that they are randomly distributed in SV3T3 cells. Other investigators have, however, proposed that these differences result from the effect of cryoprotectants and are blocked by aldehyde fixation. The experiments described in this paper re-examine PMP topography in large samples of 3T3 and SV3T3 cells prepared by a variety of preparative methods. The results confirm that 3T3 cells contain aggregated intramembranous particles and that native SV3T3 cells do not, regardless of whether cells are prepared in glycerol, sucrose, tissue culture medium or following prefixation in paraformaldehyde.
Data presented in this paper also show that cytochalasin B induces dose -and time-dependent disaggregations of particles in contact-inhibited 3T3 cells. Particle disaggregation results from exposure of cells in situ for 1-3 h to 1-500 ng/ml cytochalasin B. Removal of the drug by washing with reincubation of cells in medium containing serum results in particle reaggregation within 1 to 3 h.
These observations suggest that intramembranous particles in 3T3 cells are aggregated in the native state and that membrane-active drugs modulate their distribution by a mechanism possibly involving disruption of linkages between membrane components and the cytoskeleton.
Ultrastructural and radioautographic investigation of the nucleolar cycle in Physarum polycephalum. characterization of dna-containing subunits
Authors: Lord A. , Nicole L. , Lafontaine J. G. 
Published: April 2021

ABSTRACT
The present study has been mainly focused on the nucleolar cycle in the slime mould Physarum polycephalum. The ultrastructural characteristics of the interphase nucleolus, in this species, are quite similar to those of nucleoli in other organisms: it is essentially constituted of large particulate zones surrounding denser regions which are predominantly fibrillar in texture. The latter nucleolar zones, following fixation with osmium tetroxide, are characterized by the presence of opaque granules approximately 25 nm in diameter. Contrary to the situation which generally prevails in other eukaryotes, the late prophase nucleolus fragments into numerous globular bodies which are recognizable by the presence of opaque particles. These fibrillogranular nucleolar fragments persist during mitosis and are observed to become incorporated in the newly formed nucleolus. High-resolution radioautographic observations reveal that these nucleolar remnants contain DNA. The present observations together with recent biochemical data from other authors on the characteristics and mode of duplication of nucleolar DNA in P. polycephalum have led us to the hypothesis that the nucleolus, in this organism, contains several distinct globular subunits each containing ribosomal DNA as a key component. The existence of such morphological subunits appears to account for the unusual behaviour of the nucleolus during the cell cycle.
Brain endothelial tricellular junctions as novel sites for T cell diapedesis across the blood–brain barrier
Authors: Castro Dias Mariana , Odriozola Quesada Adolfo , Soldati Sasha , Bösch Fabio , Gruber Isabelle , Hildbrand Tobias , Sönmez Derya , Khire Tejas , Witz Guillaume , McGrath James L. , Piontek Jörg , Kondoh Masuo , Deutsch Urban , Zuber Benoît , Engelhardt Britta 
Published: April 2021

ABSTRACT
The migration of activated T cells across the blood–brain barrier (BBB) is a critical step in central nervous system (CNS) immune surveillance and inflammation. Whereas T cell diapedesis across the intact BBB seems to occur preferentially through the BBB cellular junctions, impaired BBB integrity during neuroinflammation is accompanied by increased transcellular T cell diapedesis. The underlying mechanisms directing T cells to paracellular versus transcellular sites of diapedesis across the BBB remain to be explored. By combining in vitro live-cell imaging of T cell migration across primary mouse brain microvascular endothelial cells (pMBMECs) under physiological flow with serial block-face scanning electron microscopy (SBF-SEM), we have identified BBB tricellular junctions as novel sites for T cell diapedesis across the BBB. Downregulated expression of tricellular junctional proteins or protein-based targeting of their interactions in pMBMEC monolayers correlated with enhanced transcellular T cell diapedesis, and abluminal presence of chemokines increased T cell diapedesis through tricellular junctions. Our observations assign an entirely novel role to BBB tricellular junctions in regulating T cell entry into the CNS.
This article has an associated First Person interview with the first author of the paper.
More evidence for replication-transcription-coupling in Physarum polycephalum
Authors: Pierron GÉrard , Sauer Helmut W. 
Published: April 2021

ABSTRACT
Endogenous RNA polymerase activity of isolated nuclei from Physarum polycephalum was determined at high (400 mM KC1) and low (5 – 100 rπM KC1) ionic strength.
The activity of RNA polymerase B (α-amanitin-sensitive UMP incorporation) and of RNA polymerase A (plus C) (α-amanitin-resistant UMP incorporation) was compared in accurately sized nuclear samples derived from macroplasmodia at distinct points of the mitotic cycle. Minimum total RNA polymerase activity was detected in metaphase nuclei. A constant level of RNA polymerase B activity was detected at all other stages of the mitotic cycle, if nuclei were assayed at high ionic strength. However, a high level in S-phase, a low level in G2-phase and again a high level in early prophase were measured, if nuclei were assayed at low ionic strength.
Inhibition of DNA synthesis by hydroxyurea in vivo had a selective and drastic effect on in vitro RNA polymerase activity of isolated nuclei derived from S-phase plasmodia, yielding up to 100% inhibition in early S-phase.
Red blood cell adhesion: II. Interferometric examination of the interaction with hydrocarbon oil and glass
Authors: Gingell David , Todd Ian 
Published: April 2021

ABSTRACT
Using both living and glutaraldehyde-fixed red cells, we have examined adhesion to both oil/saline and glass/saline interfaces by interference reflection microscopy. At low ionic strength, 0 ·4 mM NaCl, fixed cells adherent to the oil/saline interface show first order whitish yellow zones of closest approach which indicate a separation of ∼ 100 nm. Quantitative interferometry in monochromatic light supports this conclusion. As the salt concentration is increased the separation decreases and the final image shows zero-order black which probably indicates molecular contact with the interface. Similar but less reproducible results were obtained with fixed and unfixed cells on glass. These observations show that physical interactions alone can be responsible for adhesion in dilute and concentrated salt solutions. It is not, however, believed that the results necessarily imply the existence of adhesion with a gap in physiological concentrations of salt.
Cell junctions in the excitable epithelium of bioluminescent scales on a polynoid worm: A freeze-fracture and electrophysiological study
Authors: Bilbaut A. 
Published: April 2021

ABSTRACT
The bioluminescent scales of the polynoid worm Acholoe are covered by a dorsal and ventral monolayer of epithelium. The luminous activity is intracellular and arises from the ventral epithelial cells, which are modified as photocytes.Photogenic and non-photogenic epithelial cells have been examined with regard to intercellular junctions and electrophysiological properties. Desmosomes, septate and gap junctions are described between all the epithelial cells. Lanthanum impregnation and freeze-fracture reveal that the septate junctions belong to the pleatedtype found in molluscs, arthropods and other annelid tissues. Freeze-fractured gap junctions show polygonal arrays of membrane particles on the P face and complementary pits on the E face. Gap junctions are of the P type as reported in vertebrate, mollusc and some annelid tissues, d.c. pulses injected intracellularly into an epithelial cell are recorded in neighbouring cells. Intracellular current passage also induces propagated non-overshooting action potentials in all the epithelial cells; in photocytes, an increase of injected current elicits another response which is a propagated 2-component overshooting action potential correlated with luminous activity.
This study shows the coexistence of septate and gap junctions in a conducting and excitable invertebrate epithelium. The results are discussed in relation to the functional roles of intercellular junctions in invertebrate epithelia. It is concluded that the gap junctions found in this excitable epithelium represent the structural sites of the cell-to-cell propagation of action potentials.
Histochemical and ultrastructural characteristics of a cell line from human bone-marrow stroma
Authors: Lanotte Michel , Allen Terence D. , Dexter T. Michael 
Published: April 2021

ABSTRACT
Morphological, enzymic and antigenic data are presented regarding a human bone-marrow stromal cell line maintained for 10 months and subcultured weekly. The main characteristics are a fibroblastoid morphology, diffuse growth in collagen gels, no colony formation in soft gel media, contact inhibition of growth and conversion to adipocytes when treated with hydrocortisone. The cells are non-phagocytic and membrane Fc receptors (i.e. aggregated human immunoglobulin G receptors) are absent, but they show diffuse cytoplasmic non-specific esterase activity, a strong acid phosphatase reaction, and a negative immunofluorescence (direct and indirect) against factor VIII antigen. Other cell lines also have been isolated and maintained in culture and present similar characteristics. These cell lines are thought to be derived from the acid-phosphatase-positive marrow stroma directly associated with bone trabecular matrix and probably represent a component of the haemopoietic inductive microenvironment. As such, they may provide a useful tool for studies in vitro of cell interactions and regulatory processes in the control of human bone-marrow haemopoiesis.