Articles de revues sur le sujet « Segmental labelling »
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1
Sechrist, J., G. N. Serbedzija, T. Scherson, S. E. Fraser et M. Bronner-Fraser. « Segmental migration of the hindbrain neural crest does not arise from its segmental generation ». Development 118, no 3 (1 juillet 1993) : 691–703. http://dx.doi.org/10.1242/dev.118.3.691.
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The proposed pathways of chick cranial neural crest migration and their relationship to the rhombomeres of the hindbrain have been somewhat controversial, with differing results emerging from grafting and DiI-labelling analyses. To resolve this discrepancy, we have examined cranial neural crest migratory pathways using the combination of neurofilament immunocytochemistry, which recognizes early hindbrain neural crest cells, and labelling with the vital dye, DiI. Neurofilament-positive cells with the appearance of premigratory and early-migrating neural crest cells were noted at all axial levels of the hindbrain. At slightly later stages, neural crest cell migration in this region appeared segmented, with no neural crest cells obvious in the mesenchyme lateral to rhombomere 3 (r3) and between the neural tube and the otic vesicle lateral to r5. Focal injections of DiI at the levels of r3 and r5 demonstrated that both of these rhombomeres generated neural crest cells. The segmental distribution of neural crest cells resulted from the DiI-labelled cells that originated in r3 and r5 deviating rostrally or caudally and failing to enter the adjacent preotic mesoderm or otic vesicle region. The observation that neural crest cells originating from r3 and r5 avoided specific neighboring domains raises the intriguing possibility that, as in the trunk, extrinsic factors play a major role in the axial patterning of the cranial neural crest and the neural crest-derived peripheral nervous system.
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Ghosh, S., et A. S. Mukherjee. « Transcriptive and replicative activity of the X chromosome in an autosomal segmental hyperploid in Drosophila and its significance ». Journal of Cell Science 81, no 1 (1 mars 1986) : 267–81. http://dx.doi.org/10.1242/jcs.81.1.267.
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In the present investigation the transcription and replication patterns have been examined in different segments of the X chromosome and in certain specific segments (88B-92A) of an autosomal segmental hyperploid in which an extra segment 88B-92A (3R) is translocated to the X chromosome in addition to the normal two doses. Transcriptive activity monitored by [3H]uridine-labelling of these autosomal hyperploids reveals an enhanced hyperactivity of the male X chromosome while the female X chromosomes show no change in their activity. [3H]thymidine autoradiograms reveal that while the labelling frequencies of most replicating sites are distinctly lowered in the autosomal hyperploid males, no change within sexes is resolvable with regard to labelling-intensity profile. Furthermore, the X-autosome labelling frequency relation shows a distinct deviation from linearity, suggesting multiple events that lead to a higher template form of the X chromosome. These findings lead us to suggest that the signals emanating from autosome(s) do not interfere with the primary modulation inherent in the X chromosome, but act on a modulated organization of the same at a second step evoking higher activity in the male X chromosome. The results further reveal that the gene activity of the X chromosome remains unaffected by the pattern of pairing of the autosomal segments.
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Muona, Mikko, A. Sesilja Aranko et Hideo Iwai. « Segmental Isotopic Labelling of a Multidomain Protein by Protein Ligation by Protein Trans-Splicing ». ChemBioChem 9, no 18 (15 décembre 2008) : 2958–61. http://dx.doi.org/10.1002/cbic.200800604.
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Gavalas, A., M. Davenne, A. Lumsden, P. Chambon et F. M. Rijli. « Role of Hoxa-2 in axon pathfinding and rostral hindbrain patterning ». Development 124, no 19 (1 octobre 1997) : 3693–702. http://dx.doi.org/10.1242/dev.124.19.3693.
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Segmentation plays an important role in neuronal diversification and organisation in the developing hindbrain. For instance, cranial nerve branchiomotor nuclei are organised segmentally within the basal plates of successive pairs of rhombomeres. To reach their targets, motor axons follow highly stereotyped pathways exiting the hindbrain only via specific exit points in the even-numbered rhombomeres. Hox genes are good candidates for controlling this pathfinding, since they are segmentally expressed and involved in rhombomeric patterning. Here we report that in Hoxa-2(−/−) embryos, the segmental identities of rhombomere (r) 2 and r3 are molecularly as well as anatomically altered. Cellular analysis by retrograde dye labelling reveals that r2 and r3 trigeminal motor axons turn caudally and exit the hindbrain from the r4 facial nerve exit point and not from their normal exit point in r2. Furthermore, dorsal r2-r3 patterning is affected, with loss of cochlear nuclei and enlargement of the lateral part of the cerebellum. These results point to a novel role for Hoxa-2 in the control of r2-r3 motor axon guidance, and also suggest that its absence may lead to homeotic changes in the alar plates of these rhombomeres.
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Williams, Felix P., Alexander G. Milbradt, Kevin J. Embrey et Romel Bobby. « Segmental Isotope Labelling of an Individual Bromodomain of a Tandem Domain BRD4 Using Sortase A ». PLOS ONE 11, no 4 (29 avril 2016) : e0154607. http://dx.doi.org/10.1371/journal.pone.0154607.
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Molnár, L., et Zs Hunyadi. « Neuron clusters of segmental nerves of thoracic ganglia in Porcellio scaber retrograde labelling with lucifer yellow ». Neurobiology 9, no 1 (2001) : 43–45. http://dx.doi.org/10.1556/neurob.9.2001.1.8.
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Cui, Jing-Jing, Li-Juan Ha, Xin-Long Zhu, Hong Shi, Fu-Chun Wang, Xiang-Hong Jing et Wan-Zhu Bai. « Neuroanatomical Basis for Acupuncture Point Pc8 in the Rat : Neural Tracing Study with Cholera Toxin Subunit B ». Acupuncture in Medicine 31, no 4 (décembre 2013) : 389–94. http://dx.doi.org/10.1136/acupmed-2013-010400.
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Objectives This study was performed to investigate the innervations related to acupuncture point PC8 in rats using a neural tracing technique. Methods After 6 μL of 1% cholera toxin subunit B (CTB) was injected into the site between the second and third metacarpal bone in rats, a corresponding site to acupuncture point PC8 in the human body, CTB labelling was examined with immunofluorescence and immunohistochemistry in the dorsal root ganglia (DRG), spinal cord and brainstem. Results All CTB labelling appeared on the ipsilateral side of the injection. The labelled sensory neurons distributed from cervical (C)6 to thoracic (T)1 DRG, while the labelled motor neurons were located on the dorsolateral part of the spinal ventral horn ranging from the C6 to T1 segments. In addition, the transganglionically-labelled axonal terminals were found to be dense in the medial part of laminae 3–4 from C6 to the T1 spinal dorsal horn, as far as in the cuneate nucleus. Conclusions These results indicate that sensory and motor neurons associated with PC8 distribute in a distinct segmental pattern. The sensory information from PC8 could be transganglionically transported to the spinal dorsal horn and cuneate nucleus.
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Hanneman, E., B. Trevarrow, W. K. Metcalfe, C. B. Kimmel et M. Westerfield. « Segmental pattern of development of the hindbrain and spinal cord of the zebrafish embryo ». Development 103, no 1 (1 mai 1988) : 49–58. http://dx.doi.org/10.1242/dev.103.1.49.
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In the ventral hindbrain and spinal cord of zebrafish embryos, the first neurones that can be identified appear as single cells or small clusters of cells, distributed periodically at intervals equal to the length of a somite. In the hindbrain, a series of neuromeres of corresponding length is present, and the earliest neurones are located in the centres of each neuromere. Young neurones within both the hindbrain and spinal cord were identified in live embryos using Nomarski optics, and histochemically by labelling for acetylcholinesterase activity and expression of an antigen recognized by the monoclonal antibody zn-1. Among them are individually identified hindbrain reticulospinal neurones and spinal motoneurones. These observations suggest that early development in these regions of the CNS reflects a common segmental pattern. Subsequently, as more neurones differentiate, the initially similar patterning of the cells in these two regions diverges. A continuous longitudinal column of developing neurones appears in the spinal cord, whereas an alternating series of large and small clusters of neurones is present in the hindbrain.
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Wiegand, Thomas, Riccardo Cadalbert, Christine von Schroetter, Frédéric H. T. Allain et Beat H. Meier. « Segmental isotope labelling and solid-state NMR of a 12 × 59 kDa motor protein : identification of structural variability ». Journal of Biomolecular NMR 71, no 4 (12 juin 2018) : 237–45. http://dx.doi.org/10.1007/s10858-018-0196-z.
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Bossing, T., et G. M. Technau. « The fate of the CNS midline progenitors in Drosophila as revealed by a new method for single cell labelling ». Development 120, no 7 (1 juillet 1994) : 1895–906. http://dx.doi.org/10.1242/dev.120.7.1895.
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We present a new method for marking single cells and tracing their development through embryogenesis. Cells are labelled with a lipophilic fluorescent tracer (DiI) in their normal positions without impaling their membranes. The dye does not diffuse between cells but is transferred to the progeny, disclosing their morphology in all detail. Behaviour of labelled cells can be observed in vivo (cell divisions, morphogenetic movements and differentiation). Following photoconversion of the dye, fully differentiated clones can be analyzed in permanent preparations. We apply this method for cell lineage analysis of the embryonic Drosophila CNS. Here we describe the fate of the CNS midline cells. We present the complete lineages of these cells in the fully differentiated embryo and show that variability exists in segmental numbers of the midline progenitors as well as in the composition of their lineages.
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Rosen, Stuart, John Walliker, Judith A. Brimacombe et Bradly J. Edgerton. « Prosodic and Segmental Aspects of Speech Perception with the House/3M Single-Channel Implant ». Journal of Speech, Language, and Hearing Research 32, no 1 (mars 1989) : 93–111. http://dx.doi.org/10.1044/jshr.3201.93.
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Four adult users of the House/3M single-channel cochlear implant were tested for their ability to label question and statement intonation contours (by auditory means alone) and to identify a set of 12 intervocalic consonants (with and without lipreading). Nineteen of 20 scores obtained on the question/statement task were significantly better than chance. Simplifying the stimulating waveform so as to signal fundamental frequency alone sometimes led to an improvement in performance. In consonant identification, lipreading alone scores were always far inferior to those obtained by lipreading with the implant. Phonetic feature analyses showed that the major effect of using the implant was to increase the transmission of voicing information, although improvements in the appropriate labelling of manner distinctions were also found. Place of articulation was poorly identified from the auditory signal alone. These results are best explained by supposing that subjects can use the relatively gross temporal information found in the stimulating waveforms (periodicity, randomness and silence) in a linguistic fashion. Amplitude envelope cues are of significant, but secondary, importance. By providing information that is relatively invisible, the House/3M device can thus serve as an important aid to lipreading, even though it relies primarily on the temporal structure of the stimulating waveform. All implant systems, including multi-channel ones, might benefit from the appropriate exploitation of such temporal features.
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Hacker, A., et S. Guthrie. « A distinct developmental programme for the cranial paraxial mesoderm in the chick embryo ». Development 125, no 17 (1 septembre 1998) : 3461–72. http://dx.doi.org/10.1242/dev.125.17.3461.
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Cells of the cranial paraxial mesoderm give rise to parts of the skull and muscles of the head. Some mesoderm cells migrate from locations close to the hindbrain into the branchial arches where they undergo muscle differentiation. We have characterised these migratory pathways in chick embryos either by DiI-labelling cells before migration or by grafting quail cranial paraxial mesoderm orthotopically. These experiments demonstrate that depending on their initial rostrocaudal position, cranial paraxial mesoderm cells migrate to fill the core of specific branchial arches. A survey of the expression of myogenic genes showed that the myogenic markers Myf5, MyoD and myogenin were expressed in branchial arch muscle, but at comparatively late stages compared with their expression in the somites. Pax3 was not expressed by myogenic cells that migrate into the branchial arches despite its expression in migrating precursors of limb muscles. In order to test whether segmental plate or somitic mesoderm has the ability to migrate in a cranial location, we grafted quail trunk mesoderm into the cranial paraxial mesoderm region. While segmental plate mesoderm cells did not migrate into the branchial arches, somitic cells were capable of migrating and were incorporated into the branchial arch muscle mass. Grafted somitic cells in the vicinity of the neural tube maintained expression of the somitic markers Pax3, MyoD and Pax1. By contrast, ectopic somitic cells located distal to the neural tube and in the branchial arches did not express Pax3. These data imply that signals in the vicinity of the hindbrain and branchial arches act on migrating myogenic cells to influence their gene expression and developmental pathways.
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Wingate, R. J., et A. Lumsden. « Persistence of rhombomeric organisation in the postsegmental hindbrain ». Development 122, no 7 (1 juillet 1996) : 2143–52. http://dx.doi.org/10.1242/dev.122.7.2143.
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Rhombomeres are morphological varicosities of the neural tube that are present between embryonic day (E) 1.5 and E5 and are characterised by compartment organisation, segmentally neuronal organisation and spatially restricted patterns of gene expression. After E5, the segmented origins of the hindbrain become indistinct, while the adult hindbrain has an longitudinal columnar nuclear organisation. In order to assess the impact of the early transverse pattern on later longitudinal organisation, we have used orthotopic quail grafts and in situ hybridisation to investigate the long-term fate of rhombomeres in the embryonic chick hindbrain. The uniformity of mixing between quail and chick cells was first verified using short-term aggregation cultures. The dispersal of the progeny of individual rhombomeres (r) was then assessed by the unilateral, isochronic and orthotopic transplantation of either r2, r3, r4, r5 or r6 from quail to chick at embryonic day E2. In addition, orthotopic, partial rhombomere grafts, encompassing an inter-rhombomere boundary and adjacent rhombomere bodies were used to assess cell mixing within rhombomeres. Operated embryos were incubated to either E7 or E10 when chimaeric brains were removed. Quail cells were identified in whole mounts or serial sections using the quail-specific antibody QCPN. Subsequently, radial glia morphology was assessed either by immunohistochemistry or DiI labelling. A series of fixed hindbrains between E6 and E9 were probed for transcripts of Hoxa-2 and Hoxb-1. Fate-mapping reveals that the progeny of individual rhombomeres form stripes of cells running dorsoventrally through the hindbrain. This pattern of dispersal precisely parallels the array of radial glia. Although the postmitotic progeny of adjacent rhombomeres spread to some extent into each others' territory in intermediate and marginal zones, there is little or no mixing between rhombomeres in the ventricular zone, which thus remains compartmentalised long after the rhombomeric morphology disappears. Segmental gene expression within this layer is also maintained after E5. A more detailed analysis of mixing between proliferating cells, using partial rhombomere grafts, reveals that both mixing and growth are non-uniform within the ventricular layer, suggesting, in particular, that longitudinal expansion within this layer is restricted. Together, these observations suggest that rhombomeres do not disappear at E5, as has previously been supposed, rather they persist in the ventricular zone to at least E9, ensuring a continuity in the presumed segmental cues that specify neuroepithelial cells in the hindbrain.
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Ruberte, E., P. Dolle, P. Chambon et G. Morriss-Kay. « Retinoic acid receptors and cellular retinoid binding proteins. II. Their differential pattern of transcription during early morphogenesis in mouse embryos ». Development 111, no 1 (1 janvier 1991) : 45–60. http://dx.doi.org/10.1242/dev.111.1.45.
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In situ hybridization with 35S-labelled RNA probes was used to study the distribution of transcripts of genes coding for the retinoic acid receptors, RAR-alpha, -beta and -gamma, and the cellular binding proteins for retinoic acid (CRABP I) and retinol (CRBP I), in mouse embryos during the period of early morphogenesis. Primary mesenchyme formation was associated with CRBP I labelling of both epiblast and mesenchyme of the primitive streak, while the CRABP probe labelled the migrating primary mesenchyme cells. Neural crest cell emigration and migration were associated with CRABP labelling of both neural epithelium (excluding the floor plate) and neural crest cells, while CRBP I expression was restricted to basal and apical regions of the epithelium (excluding the floor plate). The strongest neuroepithelial signal for CRABP was in the preoptic hindbrain. RAR-beta was present in presomitic stage embryos, being expressed at highest levels in the lateral regions. RAR-alpha was associated with crest cell emigration and migration, while RAR-gamma was present in the primitive streak region throughout the period of neurulation. There was a change from RAR-beta to RAR-gamma expression at the junction between closed and open neural epithelium at the caudal neuropore. RAR-alpha and RAR-beta were expressed at specific levels of the hindbrain and in the spinal cord. These distribution patterns are discussed in relation to segmental expression patterns of other genes, and to maturational changes in the caudal neuropore region. The CRABP transcript distribution patterns correlated well with known target tissues of excess retinoid-induced teratogenesis (migrating primary mesenchyme and neural crest cells, preoptic hindbrain), providing further support for our hypothesis that cells expressing CRABP are those that cannot tolerate high levels of RA for their normal developmental function.
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Trainor, P. A., et P. P. Tam. « Cranial paraxial mesoderm and neural crest cells of the mouse embryo : co-distribution in the craniofacial mesenchyme but distinct segregation in branchial arches ». Development 121, no 8 (1 août 1995) : 2569–82. http://dx.doi.org/10.1242/dev.121.8.2569.
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The spatial distribution of the cranial paraxial mesoderm and the neural crest cells during craniofacial morphogenesis of the mouse embryo was studied by micromanipulative cell grafting and cell labelling. Results of this study show that the paraxial mesoderm and neural crest cells arising at the same segmental position share common destinations. Mesodermal cells from somitomeres I, III, IV and VI were distributed to the same craniofacial tissues as neural crest cells of the forebrain, the caudal midbrain, and the rostral, middle and caudal hindbrains found respectively next to these mesodermal segments. This finding suggests that a basic meristic pattern is established globally in the neural plate ectoderm and paraxial mesoderm during early mouse development. Cells from these two sources mixed extensively in the peri-ocular, facial, periotic and cervical mesenchyme. However, within the branchial arches a distinct segregation of these two cell populations was discovered. Neural crest cells colonised the periphery of the branchial arches and enveloped the somitomere-derived core tissues on the rostral, lateral and caudal sides of the arch. Such segregation of cell populations in the first three branchial arches is apparent at least until the 10.5-day hindlimb bud stage and could be important for the patterning of the skeletal and myogenic derivatives of the arches.
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Trainor, P. A., S. S. Tan et P. P. Tam. « Cranial paraxial mesoderm : regionalisation of cell fate and impact on craniofacial development in mouse embryos ». Development 120, no 9 (1 septembre 1994) : 2397–408. http://dx.doi.org/10.1242/dev.120.9.2397.
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A combination of micromanipulative cell grafting and fluorescent cell labelling techniques were used to examine the developmental fate of the cranial paraxial mesoderm of the 8.5-day early-somite-stage mouse embryo. Mesodermal cells isolated from seven regions of the cranial mesoderm, identified on the basis of their topographical association with specific brain segments were assessed for their contribution to craniofacial morphogenesis during 48 hours of in vitro development. The results demonstrate extensive cell mixing between adjacent but not alternate groups of mesodermal cells and a strict cranial-to-caudal distribution of the paraxial mesoderm to craniofacial structures. A two-segment periodicity similar to the origins of the branchial motor neurons and the distribution of the rhombencephalic neural crest cells was observed as the paraxial mesoderm migrates during formation of the first three branchial arches. The paraxial mesoderm colonises the mesenchymal core of the branchial arches, consistent with the location of the muscle plates. A dorsoventral regionalisation of cell fate similar to that of the somitic mesoderm is also found. This suggests evolution has conserved the fate of the murine cranial paraxial mesoderm as a multiprogenitor population which displays a predominantly myogenic fate. Heterotopic transplantation of cells to different regions of the cranial mesoderm revealed no discernible restriction in cell potency in the craniocaudal axis, reflecting considerable plasticity in the developmental fate of the cranial mesoderm at least at the time of experimentation. The distribution of the different groups of cranial mesoderm matches closely with that of the cranial neural crest cells suggesting the two cell populations may share a common segmental origin and similar destination.
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Williams, B. A., et C. P. Ordahl. « Emergence of determined myotome precursor cells in the somite ». Development 124, no 24 (15 décembre 1997) : 4983–97. http://dx.doi.org/10.1242/dev.124.24.4983.
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Myotome and sclerotome precursor cells are derived, respectively, from cells in the dorsomedial and ventromedial regions of the somite. To assay changes in the specification of myotomal precursor cells during somite maturation, we implanted dorsomedial quadrant fragments, from staged quail somites, next to the notochords of host chick embryos, and superimposed two additional notochords on these implants. In this notochord signalling environment, dorsomedial quadrant cells that are developmentally plastic are expected to differentiate as cartilage, while cells determined to a myogenic fate are expected to differentiate as skeletal muscle. Large numbers of differentiated chondrocytes developed from dorsomedial quadrant grafts of all stages of paraxial mesoderm development tested, indicating that persistent chondrogenic potential in cells fated to form muscle and dermis can be elicited by notochord signals. Differentiated myocytes, however, appeared in two somite-stage-dependent phases. In the first phase, dorsomedial quadrants from segmental plate and early stage somites (II and IV) form small, disorganized clusters of individual myocytes. The frequency of first-phase myocluster formation increases as myogenic factor expression begins in the dorsomedial quadrant, indicating that myogenic determination assayed by this method is closely linked to the expression of myogenic factors in the dorsomedial quadrant. In the second phase, dorsomedial quadrants from somite stages XI-XIII consistently form morphologically organized muscle tissue containing large numbers of parallel-oriented, multinucleated myotubes. Mitotic labelling demonstrated that muscle precursors were determined to the muscle phenotype prior to withdrawal from the cell cycle. Thus, myogenic determination in cells of the dorsomedial quadrant is acquired at earlier stages of somite maturation than the ability to proliferate and form muscle tissue. These results are consistent with the hypothesis that successive lineages of myotome precursor cells with different mitotic and morphogenetic properties arise in the dorsomedial quadrant during somite maturation.
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Anders, Sven, Stanley R. Thompson et Roland Herrmann. « Markets segmented by regional-origin labelling with quality control ». Applied Economics 41, no 3 (février 2009) : 311–21. http://dx.doi.org/10.1080/00036840601007237.
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Mehrgardt, Philip, Seid Miad Zandavi, Simon K. Poon, Juno Kim, Maria Markoulli et Matloob Khushi. « U-Net Segmented Adjacent Angle Detection (USAAD) for Automatic Analysis of Corneal Nerve Structures ». Data 5, no 2 (14 avril 2020) : 37. http://dx.doi.org/10.3390/data5020037.
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Measurement of corneal nerve tortuosity is associated with dry eye disease, diabetic retinopathy, and a range of other conditions. However, clinicians measure tortuosity on very different grading scales that are inherently subjective. Using in vivo confocal microscopy, 253 images of corneal nerves were captured and manually labelled by two researchers with tortuosity measurements ranging on a scale from 0.1 to 1.0. Tortuosity was estimated computationally by extracting a binarised nerve structure utilising a previously published method. A novel U-Net segmented adjacent angle detection (USAAD) method was developed by training a U-Net with a series of back feeding processed images and nerve structure vectorizations. Angles between all vectors and segments were measured and used for training and predicting tortuosity measured by human labelling. Despite the disagreement among clinicians on tortuosity labelling measures, the optimised grading measurement was significantly correlated with our USAAD angle measurements. We identified the nerve interval lengths that optimised the correlation of tortuosity estimates with human grading. We also show the merit of our proposed method with respect to other baseline methods that provide a single estimate of tortuosity. The real benefit of USAAD in future will be to provide comprehensive structural information about variations in nerve orientation for potential use as a clinical measure of the presence of disease and its progression.
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Serbedzija, G. N., M. Bronner-Fraser et S. E. Fraser. « Vital dye analysis of cranial neural crest cell migration in the mouse embryo ». Development 116, no 2 (1 octobre 1992) : 297–307. http://dx.doi.org/10.1242/dev.116.2.297.
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The spatial and temporal aspects of cranial neural crest cell migration in the mouse are poorly understood because of technical limitations. No reliable cell markers are available and vital staining of embryos in culture has had limited success because they develop normally for only 24 hours. Here, we circumvent these problems by combining vital dye labelling with exo utero embryological techniques. To define better the nature of cranial neural crest cell migration in the mouse embryo, premigratory cranial neural crest cells were labelled by injecting DiI into the amniotic cavity on embryonic day 8. Embryos, allowed to develop an additional 1 to 5 days exo utero in the mother before analysis, showed distinct and characteristic patterns of cranial neural crest cell migration at the different axial levels. Neural crest cells arising at the level of the forebrain migrated ventrally in a contiguous stream through the mesenchyme between the eye and the diencephalon. In the region of the midbrain, the cells migrated ventrolaterally as dispersed cells through the mesenchyme bordered by the lateral surface of the mesencephalon and the ectoderm. At the level of the hindbrain, neural crest cells migrated ventrolaterally in three subectodermal streams that were segmentally distributed. Each stream extended from the dorsal portion of the neural tube into the distal portion of the adjacent branchial arch. The order in which cranial neural crest cells populate their derivatives was determined by labelling embryos at different stages of development. Cranial neural crest cells populated their derivatives in a ventral-to-dorsal order, similar to the pattern observed at trunk levels. In order to confirm and extend the findings obtained with exo utero embryos, DiI (1,1-dioctadecyl-3,3,3′,3′-tetramethylindo-carbocyanine perchlorate) was applied focally to the neural folds of embryos, which were then cultured for 24 hours. Because the culture technique permitted increased control of the timing and location of the DiI injection, it was possible to determine the duration of cranial neural crest cell emigration from the neural tube. Cranial neural crest cell emigration from the neural folds was completed by the 11-somite stage in the region of the rostral hindbrain, the 14-somite stage in the regions of the midbrain and caudal hindbrain and not until the 16-somite stage in the region of the forebrain. At each level, the time between the earliest and latest neural crest cells to emigrate from the neural tube appeared to be 9 hours.(ABSTRACT TRUNCATED AT 400 WORDS)
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Vogl, Dominik P., Anne C. Conibear et Christian F. W. Becker. « Segmental and site-specific isotope labelling strategies for structural analysis of posttranslationally modified proteins ». RSC Chemical Biology, 2021. http://dx.doi.org/10.1039/d1cb00045d.
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Gallagher, Christopher, Fabienne Burlina, John Offer et Andres Ramos. « A method for the unbiased and efficient segmental labelling of RNA-binding proteins for structure and biophysics ». Scientific Reports 7, no 1 (26 octobre 2017). http://dx.doi.org/10.1038/s41598-017-13950-8.
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Niederacher, Gerhard, Debra Urwin, Yasmin Dijkwel, David J. Tremethick, K. Johan Rosengren, Christian F. W. Becker et Anne C. Conibear. « Site-specific modification and segmental isotope labelling of HMGN1 reveals long-range conformational perturbations caused by posttranslational modifications ». RSC Chemical Biology, 2021. http://dx.doi.org/10.1039/d0cb00175a.
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Using protein semi-synthesis, segmentally isotope-labelled variants of nucleosome-binding protein HMGN1 were generated with site-specific posttranslational modifications to explore their structural and functional effects.
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« Spinal cord neuron classes in embryos of the smooth newt Triturus vulgaris : a horseradish peroxidase and immunocytochemical study ». Philosophical Transactions of the Royal Society of London. Series B : Biological Sciences 340, no 1291 (29 avril 1993) : 141–60. http://dx.doi.org/10.1098/rstb.1993.0053.
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Spinal cord neurons were investigated in embryos of Triturus vulgaris , the smooth newt, just prior to hatching. These embryos can swim if freed from their egg membranes. Horseradish peroxidase (HRP) labelling, together with GABA and glycine immunocytochemistry (ICC), revealed nine distinct anatomical classes of neuron. 1. Ventrolateral motorneurons with mainly dorsal dendrites, sometimes a descending central axon and peripheral axon innervating the trunk muscles. 2. Dorsal primary sensory Rohon-Beard neurons innervating skin and with dorsal ascending and descending axons in spinal cord. 3. Commissural interneurons with mid-cord unipolar soma, glycine-like immunoreactivity, dendrites on initial segment of ventral axon which crosses cord to ascend or branch. 4. Dorsolateral commissural interneurons with multipolar soma in dorsolateral position with dorsal dendrites and ventral axon which crosses and ascends or branches. 5. Giant dorsolateral commissural interneurons with large dorsolateral somata widely spaced (130- 250 µm spacing) with process projecting dorsally to other side, dorsolateral dendrites and ventral axon which crosses to ascend and branch. 6. Dorsolateral ascending interneurons in dorsolateral position with multipolar soma and ascending axon on same side. 7. Ascending interneurons with unipolar soma, GABA-like immunoreactivity and ascending axon on same side. 8. Descending interneurons with bi- or multi-polar soma, extensive dorsal and ventral dendrites, and descending axon on same side. They may also have ascending axons. 9. Kolmer-Agduhr cerebrospinal fluid contacting neurons with cilia and microvilli in lateral corners of neural canal, GABA-like immunoreactivity, no dendrites and ascending axon. Eight of the nine cell classes were found to bear a marked resemblance to neurons previously described in zebrafish and Xenopus embryos in terms of their anatomy, distribution and immunoreactivity to GABA and glycine. Homologies and possible functions are discussed. Giant dorsolateral commissural neurons, were not found in Xenopus or teleosts but were present in Ambystoma mexicanum and Neoceratodus . The regular, possibly segmental longitudinal distribution pattern of these cells within the cord is unusual amoung amphibian spinal neurons.
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Zwanenburg, F., J. C. Van Munsteren, L. J. Wisse, M. C. De Ruiter, M. C. Haak et M. R. M. Jongbloed. « Aortic stenosis : correlation of prenatal echocardiography to postmortem histology ». European Heart Journal 42, Supplement_1 (1 octobre 2021). http://dx.doi.org/10.1093/eurheartj/ehab724.1842.
Texte intégralRésumé :
Abstract Background Foetal aortic stenosis (AS) is a challenging congenital heart disease considering its potential to progress during the course of pregnancy. Especially at midgestation, it remains extremely difficult to distinguish the cases that end up biventricular from the cases that will develop into an hypoplastic left heart syndrome. Purpose To test the hypothesis that the degree of myocardial maturation is a possible predictor of biventricular outcome, we present 4 cases of foetal AS with a varying degree of severity and uniquely correlate differences in myocardial function based on prenatal echocardiography to their post-mortem histopathologic maturation. Methods We selected 4 cases with midgestational AS from our tertiary foetal cardiology service between 2018–2020. Speckle tracking recordings of the cardiac four-chamber view were performed during routine foetal echocardiography to quantify myocardial wall motion as a marker for myocardial function. Three cases decided to terminate the pregnancy and donated the cardiac specimen. Immunohistochemical labelling (ICH) against key markers for myocardial maturation (troponin-I, N-cadherin, connexin-43, MLC2A, MLC2V and α-SMA) and fibrosis (Sirius Red) were compared with 2 normal foetal cardiac specimens. Results Two cases with critical AS presented extremely decreased global and segmental longitudinal strain (GLS and SLS) values (GLS −2% and −0.9%) in the left ventricle (LV), indicating an impaired myocardial wall deformation. Post-mortem ICH showed overt endocardial fibro-elastosis (EFE) and pathological fibrosis patterns in the subendocardial layer which was remarkably spatially correlated to the EFE. The cardiomyocytes were disorganised with reduced expression of troponin-I and disturbed expression of connexin-43. The remaining 2 cases had normal LV appearance on foetal echocardiography, showing a mild reduction in left ventricular GLS and SLS (GLS −11.8% and −14.2%). Post-mortem ICH of 1 of these cases showed mild EFE with a milder fibrosis pattern. Cardiomyocytes were less disorganised but also showed a disturbed expression of connexin-43. The 4th case continued the pregnancy and had a biventricular outcome. Conclusions This is a unique case series showing that myocardial function correlates with high extent to histology. The degree of the reduction in myocardial function corresponded with the amount of pathological fibrosis patterns and disorganisation of the cardiomyocyte network. Myocardial wall motion on foetal echocardiography seems to hold promise as a possible marker for cardiac maturation. Funding Acknowledgement Type of funding sources: None. Speckle tracking and fibrosis patterns
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Fernández, Esteban, Shengjie Yang, Sy Han Chiou, Chul Moon, Cong Zhang, Bo Yao, Guanghua Xiao et Qiwei Li. « SAFARI : shape analysis for AI-segmented images ». BMC Medical Imaging 22, no 1 (22 juillet 2022). http://dx.doi.org/10.1186/s12880-022-00849-8.
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Abstract Background Recent developments to segment and characterize the regions of interest (ROI) within medical images have led to promising shape analysis studies. However, the procedures to analyze the ROI are arbitrary and vary by study. A tool to translate the ROI to analyzable shape representations and features is greatly needed. Results We developed SAFARI (shape analysis for AI-segmented images), an open-source package with a user-friendly online tool kit for ROI labelling and shape feature extraction of segmented maps, provided by AI-algorithms or manual segmentation. We demonstrated that half of the shape features extracted by SAFARI were significantly associated with survival outcomes in a case study on 143 consecutive patients with stage I–IV lung cancer and another case study on 61 glioblastoma patients. Conclusions SAFARI is an efficient and easy-to-use toolkit for segmenting and analyzing ROI in medical images. It can be downloaded from the comprehensive R archive network (CRAN) and accessed at https://lce.biohpc.swmed.edu/safari/.
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Saha, Sunita, Amalia Siatou, Alamin Mansouri et Robert Sitnik. « Supervised segmentation of RTI appearance attributes for change detection on cultural heritage surfaces ». Heritage Science 10, no 1 (29 octobre 2022). http://dx.doi.org/10.1186/s40494-022-00813-3.
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AbstractThis paper proposes a supervised segmentation method for detecting surface changes based on appearance attributes, focusing on cultural heritage metal surfaces. Reflectance Transformation Imaging (RTI) reconstruction coefficients (PTM and HSH) are explored for tracking changes over time on different data sets. Each acquisition is normalised to ensure the method’s robustness, allowing consecutive acquisitions with different RTI acquisition parameters. The proposed method requires expert labelling on groups of pixels representing individual classes. Afterward, the surface appearance is identified over time based on the estimated discriminant model. After segmentation, each detected category is assigned to a single colour to present the results with a user-friendly colourmap visualisation. The method is user-dependent; the labelling of the pixels must be accurately defined based on the research question. The results were evaluated based on human expertise in the conservation-restoration field and are considered ground truth in this work. A case study with visibly segmentable characteristics was used to prove the concept and evaluate the invariance of the proposed method. Comparison with the segmentation of the visible characteristics shows very accurate segmentation for HSH (99%) and lower for PTM (80%), which is influenced by surface rotation. The method was tested on metal surfaces undergoing accelerated corrosion or cleaning treatments. The results were promising for tracking changes based on segmentation. Equally promising is the possibility of qualitative quantifying the degree of change by counting the change of a selected class of pixels. PTM and HSH results are comparable in cases of mat surfaces; however, in high specular surfaces, HSH seems to provide more detailed information and, therefore, can better depict the surface characteristics. Limitations of the application are related to the possibility of identifying surface characteristics that do not exhibit topographic changes or significant reflectance differentiation.