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Cortical Layers (cortical + layer)
Selected AbstractsOrganization of GABAA receptor ,-subunit clustering in the developing rat neocortex and hippocampusEUROPEAN JOURNAL OF NEUROSCIENCE, Issue 9 2004B. Hutcheon Abstract We compared the expression and co-expression of ,1, ,2, ,3, and ,5-subunit protein clusters of the ,-aminobutyric acid (GABA)A receptor in the neocortex and hippocampus of rat at postnatal days (PND) 5,10 and 30,40 in order to understand how inhibitory receptors reorganize during brain maturation. The size, intensity, density and pattern of co-localization of fluorescently tagged subunit clusters were determined in deconvolved digital images using a novel 2D cross-correlational analysis. The cross-correlation analysis allowed an unbiased identification of GABAA receptor subunit clusters based on staining intensity. Cluster size increased through development; only the ,2 clusters in dentate gyrus (DG) decreased in size. ,5-subunit cluster density either increased or decreased with maturation depending on the brain region. For the other subunits, the cluster density remained rather constant, with noted exceptions (increase in ,2 clusters in cortical layer 5 but a decrease of ,3 clusters in hilus). The co-localization of ,1-subunit with the others was unique and not correlated to overall changes in subunit abundance between developmental époques. So, although ,2-subunit expression went up in the DG, the clusters became less co-localized with ,1. In contrast, ,5-subunit clusters became more co-localized with ,1 as the ,5-subunit expression declined in cortex and CA1. The co-localization of ,3 with ,1 also became greater in layer 6. In the adult brain not all clustering was associated with synapses, as many ,-subunit clusters did not co-localize with synaptophysin. Overall, these data indicate that the regulation of GABAA receptor clustering is both synaptic and extrasynaptic, presumably reflecting complex cellular trafficking mechanisms. [source] An In Vitro Study of the Ultrasonic Axial Transmission Technique at the Radius: 1-MHz Velocity Measurements Are Sensitive to Both Mineralization and Intracortical Porosity,JOURNAL OF BONE AND MINERAL RESEARCH, Issue 9 2004Emmanuel Bossy Abstract The ultrasonic axial transmission technique allows for investigating skeletal sites such as the cortical layer of long bones (radius, tibia, phalanges). Using synchrotron radiation ,CT, we investigated, in vitro, the relationships between 1-MHz axial transmission SOS measurements at the radius and site-matched measurements of C.Th, POR, MIN, and vBMD. Introduction: The ultrasonic axial transmission technique allows for investigating skeletal sites such as the cortical layer of long bones (radius, tibia, phalanges). Materials and Methods:Using synchrotron radiation ,CT, we investigated, in vitro, the relationships between 1-MHz axial transmission speed of sound (SOS) measurements at the radius and site-matched measurements of cortical thickness (C.Th), intracortical porosity (POR), tissue mineralization (MIN), and volumetric BMD (vBMD). SOS measurements were based on bidirectional axial transmission and were performed with a 1-MHz proprietary probe on 39 excised human radii. Results: The highest correlations between SOS values and bone parameters (R2SOS/POR = 0.28, p < 10,3; R2SOS/MIN = 0.38, p < 10,4; R2SOS/vBMD = 0.57, p < 10,3) were found for bone parameters assessed in a 1-mm-thick periosteal region of the cortex rather than throughout the whole cortex. The observed moderate correlation between SOS and C.Th values (R2SOS/C.Th = 0.20, p < 10,2) disappeared when controlled for other variables. The two best multilinear predictive models, including either BMD alone or the pair of dependent variables MIN and POR (all assessed in the periosteal cortex), were equally accurate in predicting SOS values (R2SOS/(POR,MIN) = 0.59, p < 10,5; R2SOS/vBMD = 0.57, p < 10,5). Conclusion: For the first time, the respective adjusted contributions of POR (,24 m/s%,1) and tissue mineralization (+3.5 m/s/mg/cm,3) to SOS values were assessed. These results suggest potential sensitivity of axial transmission SOS values to changes in cortical bone status under different pathological conditions or treatments affecting POR and/or tissue mineralization. [source] The heart of the South American rattlesnake, Crotalus durissusJOURNAL OF MORPHOLOGY, Issue 9 2010Bjarke Jensen Abstract Most anatomical and physiological studies of the sauropsid heart have focused on species with extraordinary physiologies, and detailed anatomical descriptions of hearts from sauropsids with more common physiologies are therefore warranted. Here, we present a comprehensive study of the cardiac anatomy of the South American rattlesnake (Crotalus durissus). The cardiovascular physiology of this species has been investigated in a number of studies, whereas only a few cursory studies exist on the cardiac anatomy of viperid snakes. The heart of C. durissus is typically squamate in many regards. Both atria are thin-walled sacs, and the right atrium is the most voluminous. The single ventricle contains three major septa; the vertical septum, the muscular ridge (MR), and the bulbuslamelle. These partially divide the ventricle into three chambers; the systemic and left-sided cavum arteriosum (CA), the pulmonary and right-sided cavum pulmonale, and the medial cavum venosum (CV). The MR is the most developed septum, and several additional and minor septa are found within the CA and CV. An extraordinary thin cortical layer encloses the ventricle, and it is irrigated by a remarkably rich arborization of coronary arteries. Previous studies show high degrees of blood flow separation in the Crotalus heart, and this can only be explained by the coordinated actions of the septa and the prominent atrioventricular valves. J. Morphol. 271:1066-1077, 2010. © 2010 Wiley-Liss, Inc. [source] Laminar variation in neuronal viability and trophic dependence in neocortical slicesJOURNAL OF NEUROSCIENCE RESEARCH, Issue 5 2001Mary M. Niblock Abstract Organotypic slices are used frequently in studies of central nervous system development and function because they provide excellent experimental access with significant preservation of cellular context and relationships. Within a slice, however, a variety of factors may cause individual classes of neurons to respond differently to the culture environment. Differences in deafferentation, cellular maturation, trophic dependence and ongoing naturally occurring cell death may produce changes in the neuronal population that are transparent to the experimenter but that could affect experimental results significantly. In this study, we examined the distribution and prevalence of cell death among neurons in each cortical layer in organotypic slices. In addition, we assessed the ability of several neurotrophic factors to ameliorate neuronal death in each cortical layer. Within the first 24 hr in culture, there was striking laminar variation in the extent of neuronal death in culture, which could not be accounted for by the pattern of programmed cell death in vivo. In addition, neurons in the six layers of the neocortex differed in the degree to which they could be rescued by neurotrophic factors. These data suggest that differential neuronal death and rescue are important considerations in studies utilizing organotypic slices and may represent particularly confounding variables in studies of effects of trophic factors in such preparations. J. Neurosci. Res. 65:455,462, 2001. © 2001 Wiley-Liss, Inc. [source] Proteomic analysis reveals protein changes within layer 2 of the insular cortex in schizophreniaPROTEINS: STRUCTURE, FUNCTION AND BIOINFORMATICS, Issue 23-24 2008Kyla Pennington Abstract Abnormalities in the size and activity of the insular cortex (IC), a brain region involved in auditory hallucinations and language, have been previously found in brain imaging studies in schizophrenia. In addition, cortical layer 2 has been shown to be abnormal in many brain regions in schizophrenia. In this study, 2-D DIGE was used to quantitatively analyse protein expression in schizophrenia and control cases (n,=,15/group) in microdissected layer 2 IC tissue. Proteomic analyses revealed 57 significantly differentially expressed (p<0.05) protein spots in schizophrenia. Validation of differential expression of two of the proteins differentially expressed was subsequently confirmed using Western blotting. This work provides evidence of abnormal protein expression in layer 2 of the IC in schizophrenia, supporting previous work of reduced neuronal size in this cortical layer in the IC. Over half of proteins abnormally expressed in this study have not been reported previously in proteomic studies investigating schizophrenia or neurodegenerative disorders. Proteins found to be abnormally expressed appear to collectively impact on neuronal plasticity through roles in neurite outgrowth, cellular morphogenesis and synaptic function. [source] Three-dimensional average-shape atlas of the honeybee brain and its applicationsTHE JOURNAL OF COMPARATIVE NEUROLOGY, Issue 1 2005Robert Brandt Abstract The anatomical substrates of neural nets are usually composed from reconstructions of neurons that were stained in different preparations. Realistic models of the structural relationships between neurons require a common framework. Here we present 3-D reconstructions of single projection neurons (PN) connecting the antennal lobe (AL) with the mushroom body (MB) and lateral horn, groups of intrinsic mushroom body neurons (type 5 Kenyon cells), and a single mushroom body extrinsic neuron (PE1), aiming to compose components of the olfactory pathway in the honeybee. To do so, we constructed a digital standard atlas of the bee brain. The standard atlas was created as an average-shape atlas of 22 neuropils, calculated from 20 individual immunostained whole-mount bee brains. After correction for global size and positioning differences by repeatedly applying an intensity-based nonrigid registration algorithm, a sequence of average label images was created. The results were qualitatively evaluated by generating average gray-value images corresponding to the average label images and judging the level of detail within the labeled regions. We found that the first affine registration step in the sequence results in a blurred image because of considerable local shape differences. However, already the first nonrigid iteration in the sequence corrected for most of the shape differences among individuals, resulting in images rich in internal detail. A second iteration improved on that somewhat and was selected as the standard. Registering neurons from different preparations into the standard atlas reveals 1) that the m-ACT neuron occupies the entire glomerulus (cortex and core) and overlaps with a local interneuron in the cortical layer; 2) that, in the MB calyces and the lateral horn of the protocerebral lobe, the axon terminals of two identified m-ACT neurons arborize in separate but close areas of the neuropil; and 3) that MB-intrinsic clawed Kenyon cells (type 5), with somata outside the calycal cups, project to the peduncle and lobe output system of the MB and contact (proximate) the dendritic tree of the PE1 neuron at the base of the vertical lobe. Thus the standard atlas and the procedures applied for registration serve the function of creating realistic neuroanatomical models of parts of a neural net. The Honeybee Standard Brain is accessible at www.neurobiologie.fu-berlin.de/beebrain. J. Comp. Neurol. 492:1,19, 2005. © 2005 Wiley-Liss, Inc. [source] Influence of surgical technique and surface roughness on the primary stability of an implant in artificial bone with different cortical thickness: a laboratory studyCLINICAL ORAL IMPLANTS RESEARCH, Issue 2 2010Afsheen Tabassum Abstract Objective: The aim of this biomechanical study was to assess the interrelated effect of both surface roughness and surgical technique on the primary stability of dental implants. Material and methods: For the experiment, 160 screw-designed implants (Biocomp®), with either a machined or an etched surface topography, were inserted into polyurethane foam blocks (Sawbones®). As an equivalent of trabecular bone, a density of 0.48 g/cm3 was chosen. To mimic the cortical layer, on top of these blocks short-fibre-filled epoxy sheets were attached with a thickness varying from 0 to 2.5 mm. The implant sites were prepared using either a press-fit or an undersized technique. To measure the primary stability of the implant, both the insertion and the removal torques were scored. Results: Independent of the surgical technique used, both implant types showed an increased insertion and removal torque values with increasing cortical thickness, although >2 mm cortical layer no further increase in insertion torque was observed. In the models with only trabecular bone (without cortical layer) and with a 1 mm cortical layer, both implant types showed a statistically higher insertion and removal torque values for undersized compared with the press-fit technique. In addition, etched implants showed a statistically higher insertion and removal torque mean values compared with machined implants. In the models with 2 and 2.5 mm cortical layers, with respect to the insertion torque values, no effect of either implantation technique or implant surface topography could be observed. Conclusion: The placement of etched implants in synthetic bone models using an undersized preparation technique resulted in enhanced primary implant stability. A correlation was found between the primary stability and the cortical thickness. However, at or above a cortical thickness of 2 mm, the effect of both an undersized surgical approach, as also the presence of a roughened (etched) implant surface, had no extra effect. Besides the mechanical aspects, the biological effect of undersized drilling, i.e. the bone response on the extra insertion torque forces should also be elucidated. Therefore, additional in vivo studies are needed. To cite this article: Tabassum A, Meijer GJ, Wolke JGC, Jansen JA. Influence of surgical technique and surface roughness on the primary stability of an implant in artificial bone with different cortical thickness: a laboratory study. Clin. Oral Impl. Res. 21, 2010; 213,220. doi: 10.1111/j.1600-0501.2009.01823.x [source] Tissue engineering of periosteal cell membranes in vitroCLINICAL ORAL IMPLANTS RESEARCH, Issue 8 2009Patrick H. Warnke Abstract: Objectives: The cultivation of bone is a major focus in tissue engineering and oral implantology. Without a periosteal layer, instant or rapid development of a substantial cortical layer is unlikely for engineered bone grafts. The aim of this study was to test the ability of four collagen membranes to support and promote the proliferation of human periosteal cells. Materials and methods: Human periosteum cells were cultured using an osteogenic medium consisting of Dulbecco's modified Eagle's medium supplemented with fetal calf serum, penicillin, streptomycin and ascorbic acid at 37°C with 5% CO2. Four collagen membranes served as scaffolds: Bio-Gide, Chondro-Gide, Tutodent and Ossix Plus. Cell vitality was assessed by fluorescin diacetate (FDA) and propidium iodide (PI) staining, biocompatibility with LDH and BrdU, MTT, WST tests and scanning electron microscopy (SEM). Results: After 24 h, all probes showed viable periosteal cells. All biocompatibility tests revealed that proliferation on all membranes after treatment with eluate from membranes after a 24-h immersion in a serum-free cell culture medium was similar to the controls. Periosteal cells formed layers covering the surfaces of all four membranes 7 days after seeding in SEM. Conclusion: It can be concluded from our data that the collagen membranes can be used as scaffolds for the cultivation of periosteum layers with a view to creating cortical bone using tissue-engineering methods. [source] Altered volume and hemispheric asymmetry of the superficial cortical layers in the schizophrenia planum temporaleEUROPEAN JOURNAL OF NEUROSCIENCE, Issue 3 2009John F. Smiley Abstract In vivo structural MRI studies in schizophrenia auditory cerebral cortex have reported smaller volumes and, less consistently, have reported altered hemispheric asymmetry of volumes. We used autopsy brains from 19 schizophrenia and 18 nonpsychiatric male subjects to measure the volume asymmetry of the planum temporal (PT). We then used the most recently autopsied 11 schizophrenia and 10 nonpsychiatric brains to measure the widths and fractional volumes of the upper (I,III) and lower (IV,VI) layers. Measurements of whole PT gray matter volumes did not show significant changes in schizophrenia. Nevertheless, laminar volume measurements revealed that the upper layers of the PT comprise a smaller fraction of the total cortex in schizophrenia than in nonpsychiatric brains. Subdivision of the PT showed that this change was especially prominent caudally, beyond Heschl's gyrus, whereas similar but less pronounced changes were found in the rostral PT and Heschl's gyrus. Complementary measures of laminar widths showed that the altered fractional volume in the caudal left PT was due mainly to ,8% thinner upper layers. However, the caudal right PT had a different profile, with thicker lower layers and comparatively unchanged upper layers. Thus, in the present study, laminar measurements provided a more sensitive method for detecting changes than measurement of whole PT volumes. Besides findings in schizophrenia, our cortical width measurements revealed normal hemispheric asymmetries consistent with previous reports. In schizophrenia, the thinner upper layers of the caudal PT suggest disrupted corticocortical processing, possibly affecting the multisensory integration and phonetic processing of this region. [source] Saccadic eye movements evoked by microstimulation of striate cortexEUROPEAN JOURNAL OF NEUROSCIENCE, Issue 4 2003Edward J. Tehovnik Abstract Experiments were performed to assess the excitability of neural elements activated while inducing saccadic eye movements electrically from different cortical layers of striate cortex (area V1) in rhesus monkeys. Excitability was assessed by measuring current thresholds, saccadic latencies, chronaxies, and the effectiveness of anode-first vs. cathode-first pulses. Minimum current thresholds for the evocation of saccades (i.e. less than 5 µA) were observed when the deepest layers of V1 were stimulated. The shortest saccadic latencies were also observed at these depths. The shortest latency at 10 times the threshold current was 49 ms on average. The chronaxies of the elements mediating saccades were less in deep V1 (i.e. 0.17 ms) than in superficial V1 (i.e. 0.23 ms). Anode-first pulses were more effective at evoking saccades from superficial V1, whereas cathode-first pulses were more effective at evoking saccades from deep V1. These results indicate that the excitability properties of superficial and deep V1 are distinct for the generation of saccades. Moreover, the excitability of elements mediating saccades in V1 of monkeys is comparable to that of elements mediating phosphenes in human V1. [source] Disabled-1 mRNA and protein expression in developing human cortexEUROPEAN JOURNAL OF NEUROSCIENCE, Issue 3 2003Gundela Meyer Abstract Disabled-1 (Dab1) forms part of the Reelin,Dab1 signalling pathway that controls neuronal positioning during brain development; Dab1 deficiency gives rise to a reeler-like inversion of cortical layers. To establish a timetable of Dab1 expression in developing human brain, Dab1 mRNA and protein expression were studied in prenatal human cortex. The earliest Dab1 signal was detected at 7 gestational weeks (GW), the stage of transition from preplate to cortical plate, suggesting a role of the Reelin,Dab1 signalling pathway in preplate partition. From 12 to 20 GW, the period of maximum cortical migration, Dab1 expression was prominent in the upper tiers of the cortical plate, to decline after midgestation. Radially orientated apical dendrites of Dab1-expressing neurons indicated a predominant pyramidal phenotype. Pyramidal cells in hippocampus and entorhinal cortex displayed a more protracted time of Dab1 expression compared to neocortex. In addition, at later stages (18,25 GW), Dab1 was also expressed in large neurons scattered throughout intermediate zone and subplate. From 14 to 22 GW, particularly high levels of Dab1 mRNA and protein were observed in cells of the ventricular/subventricular zone displaying the morphology of radial glia. The partial colocalization of vimentin and Dab1 in cells of the ventricular zone supported a radial glia phenotype. The concentration of Dab1 protein in ventricular endfeet and initial portions of radial processes of ventricular-zone cells points to a possible involvement of Dab1 in neurogenesis. Furthermore, a subset of Cajal,Retzius cells in the marginal zone colocalized Dab1 and Reelin, and may thus represent a novel target of the Reelin,Dab1 signalling pathway. [source] Enhanced T2 contrast for MR histology of the mouse brainMAGNETIC RESONANCE IN MEDICINE, Issue 4 2006Anjum Ali Sharief Abstract A 3D Carr-Purcell-Meiboom-Gill (CPMG) sequence was implemented to obtain enhanced T2 contrast in actively stained (perfusion with fixative and contrast agent) mouse brains at 9.4 T. Short interecho spacing was used to minimize diffusion and susceptibility losses. The sequence produced 16 3D volumes with an interecho spacing of 7 ms for isotropic 43-,-resolution images of the mouse brains in a scan time of 4 hr. To enhance the signal-to-noise ratio (SNR) and contrast, the multiecho frequency domain image contrast (MEFIC) method was applied, resulting in a composite image with T2 -weighted contrast. The high SNR and contrast thus achieved revealed aspects of mouse brain morphology, such as multiple cortical layers, groups of thalamic nuclei, layers of the inferior and superior colliculus, and molecular and granular layers of the cerebellum, with a high degree of definition and contrast that was not previously achieved in T2 -weighted acquisitions at high fields. Magn Reson Med, 2006. © 2006 Wiley-Liss, Inc. [source] Pick's disease with Pick bodies combined with progressive supranuclear palsy without tuft-shaped astrocytes: A clinical, neuroradiologic and pathological study of an autopsied caseNEUROPATHOLOGY, Issue 3 2006Lu-Ning Wang We report clinical, neuroradiologic features, and neuropathologic findings of a 76-year-old man with coexistent Pick's disease and progressive supranuclear palsy. The patient presented with loss of recent memory, abnormal behavior and change in personality at the age of 60. The symptoms were progressive. Three years later, repetitive or compulsive behavior became prominent. About 9 years after onset, he had difficulty moving and became bed-ridden because of a fracture of his left leg. His condition gradually deteriorated and he developed mutism and became vegetative. The patient died from pneumonia 16 years after the onset of symptoms. Serial MRI scans showed progressive cortex atrophy, especially in the bilateral frontal and temporal lobes. Macroscopic inspection showed severe atrophy of the whole brain, including cerebrum, brainstem and cerebellum. Microscopic observations showed extensive superficial spongiosis and severe neuronal loss with gliosis in the second and third cortical layers in the frontal, temporal and parietal cortex. There were Pick cells and argyrophilic Pick bodies, which were tau- and ubiquitin-positive in neurons of layers II,III of the above-mentioned cortex. Numerous argyrophilic Pick bodies were observed in the hippocampus, especially in the dentate fascia. In addition, moderate to severe loss of neurons was found with gliosis and a lot of Gallyas/tau-positive globus neurofibrillary tangles in the caudate nucleus, globus pallidus, thalamus, substantia nigra, locus coeruleus and dentate nucleus. Numerous thorned-astrocytes and coiled bodies but no-tuft shaped astrocytes were noted in the basal ganglion, brainstem and cerebellar white matter. In conclusion, these histopathological features were compatible with classical Pick's disease and coexistence with progressive supranuclear palsy without tuft-shaped astrocytes. [source] Leptomeningeal carcinomatosis from urinary bladder adenocarcinoma: A clinicopathological case studyNEUROPATHOLOGY, Issue 1 2005Kaoru Sugimori We report a 73-year-old male patient with leptomeningeal metastasis from urinary bladder adenocarcinoma. He was presented, with, prominent, hyperactive, delirium, during the course of the disease. Meningeal carcinomatosis was detected 5 days before his death, but the primary site of the malignant tumor could not be determined. Necropsy revealed leptomeningeal infiltration of many adenocarcinoma cells that covered the cerebrum. The leptomeninges of the right middle frontal gyrus, superior temporal gyrus, precentral gyrus and inferior parietal lobe were most severely affected by tumor cell infiltration. Cerebral edema was found to extensively cover the basal part of the temporal lobe. In the cerebrum, tumor cells were clustered in the perivascular spaces and had invaded localized areas of the frontal lobe. Vascular cell adhesion molecule (VCAM)-1 expression was detected in the small vessels of the cerebral upper cortical layers and of temporal subcortical u-fibers. Numerous astrocytes positive for cytokeratin AE1/AE3 were found in the frontal and temporal lobes. Meningeal carcinomatosis from urinary bladder adenocarcinoma is extremely rare and up-regulation of the adhesion molecules in the meningeal adenocarcinoma was confirmed. [source] Development, dilation and subdivision of cortical layers of gentian (Gentiana asclepiadea) rootNEW PHYTOLOGIST, Issue 1 2003ottníková Summary ,,The structure and development of the cortical layers, especially the endodermis and exodermis, and changes in the cortex caused by the secondary growth of vascular tissues are described in the adventitious roots of gentian (Gentiana asclepiadea). ,,Sections along the whole axis of the soil-grown roots were observed using light microscopy; fluorescence microscopy was used to determine developmental stages of the endodermis and exodermis. ,,Both endodermis and exodermis develop in three stages: Casparian band formation, suberin lamellae deposition and secondary thickening of walls. After the onset of cambial activity (20 mm from apex) cortical cells expand tangentially and subdivision of individual cells starts between 20 mm and 60 mm from apex. Highly differentiated endodermal cells are divided by 0,19 new anticlinal walls, exodermal cells by 0,3 and parenchymatous mid-cortex by 0,1. ,,The additional anticlinal cell walls of the endodermis and exodermis possess neither Casparian bands nor suberin lamellae. Suberin lamellae remain continuous on the surface of extended tangential walls of both layers. There is a correlation between increasing diameter of the secondary vascular tissues and the number of endodermal cells created by subdivision of the original cells. [source] The role of lateral roots in bypass flow in rice (Oryza sativa L.)PLANT CELL & ENVIRONMENT, Issue 5 2010BUALUANG FAIYUE ABSTRACT Although an apoplastic pathway (the so-called bypass flow) is implicated in the uptake of Na+ by rice growing in saline conditions, the point of entry of this flow into roots remains to be elucidated. We investigated the role of lateral roots in bypass flow using the tracer trisodium-8-hydroxy-1,3,6-pyrenetrisulphonic acid (PTS) and the rice cv. IR36. PTS was identified in the vascular tissue of lateral roots using both epifluorescence microscopy and confocal laser scanning microscopy. Cryo-scanning electron microscopy and epifluorescence microscopy of sections stained with berberine-aniline blue revealed that the exodermis is absent in the lateral roots. We conclude that PTS can move freely through the cortical layers of lateral roots, enter the stele and be transported to the shoot via the transpiration stream. [source] Nuclear factor I gene expression in the developing forebrainTHE JOURNAL OF COMPARATIVE NEUROLOGY, Issue 3 2008Céline Plachez Abstract Three members of the Nuclear Factor I (Nfi) gene family of transcription factors; Nfia, Nfib, and Nfix are highly expressed in the developing mouse brain. Nfia and Nfib knockout mice display profound defects in the development of midline glial populations and the development of forebrain commissures (das Neves et al. [1999] Proc Natl Acad Sci U S A 96:11946,11951; Shu et al. [2003] J Neurosci 23:203,212; Steele-Perkins et al. [2005] Mol Cell Biol 25:685,698). These findings suggest that Nfi genes may regulate the substrate over which the commissural axons grow to reach targets in the contralateral hemisphere. However, these genes are also expressed in the cerebral cortex and, thus, it is important to assess whether this expression correlates with a cell-autonomous role in cortical development. Here we detail the protein expression of NFIA and NFIB during embryonic and postnatal mouse forebrain development. We find that both NFIA and NFIB are expressed in the deep cortical layers and subplate prenatally and display dynamic expression patterns postnatally. Both genes are also highly expressed in the developing hippocampus and in the diencephalon. We also find that principally neither NFIA nor NFIB are expressed in callosally projecting neurons postnatally, emphasizing the role for midline glial cell populations in commissure formation. However, a large proportion of laterally projecting neurons express both NFIA and NFIB, indicating a possible cell-autonomous role for these transcription factors in corticospinal neuron development. Collectively, these data suggest that, in addition to regulating the formation of axon guidance substrates, these genes also have cell-autonomous roles in cortical development. J. Comp. Neurol. 508:385,401, 2008. © 2008 Wiley-Liss, Inc. [source] Post-natal Development of Perineuronal Nets in the Retrosplenial Cortex of Albino RatANATOMIA, HISTOLOGIA, EMBRYOLOGIA, Issue 2005R. Sayed The brain extracellular matrix (ECM) has attracted growing interest due to its highly regulated spatiotemporal expression during development and maturation of central nervous system. The present study deals with the post-natal appearance and transformation into adult distribution patterns of the ECM components related to proteoglycans (PGs) and glycoproteins (GPs) in the retrosplenial cortex (RSC) of albino rats at birth (P0), 1 week (P1), P2, P3, P4, P5, P6, P7 and P8. The differentiating PGs and GPs components of the ECM were shown to make their appearance as early as 1,2 weeks post-natally. At this developmental stage, these components of the ECM appeared in association with some neurons and glia cells or diffusely localized at the neutrophill. Interestingly, Golgi complexes of labelled neurons were usually stained with lectin VVA or WFA, and this labelling dramatically disappeared on reaching P4. During P2,3, the pericoated neuronal cells underwent a progressive increment in number, and presented an inside-out pattern of migration and differentiation (toward the V-II cortical layers). On reaching P4, most of the coated neurons appeared distributed into the cortical layer IV and II. At a later stage (P5,8), the overall density and intensity of labelled neurons progressively increased and apparently reached the adult stage of development. They also displayed the usual differential labelling characteristics, after using the cationic iron colloid/lectin staining, for the first time at this juncture. The present findings indicated that the perineuronal ECM components are significantly correlated with age and suggest a possible developmental or biological significance including promotion of migration, as well as functional maturation of the retrosplenial neurons. [source] Nonparametric One-way Analysis of Variance of Replicated Bivariate Spatial Point PatternsBIOMETRICAL JOURNAL, Issue 1 2004Sabine Landau Abstract A common problem in neuropathological studies is to assess the spatial patterning of cells on tissue sections and to compare spatial patterning between disorder groups. For a single cell type, the cell positions constitute a univariate point process and interest focuses on the degree of spatial aggregation. For two different cell types, the cell positions constitute a bivariate point process and the degree of spatial interaction between the cell types is of interest. We discuss the problem of analysing univariate and bivariate spatial point patterns in the one-way design where cell patterns have been obtained for groups of subjects. A bootstrapping procedure to perform a nonparametric one-way analysis of variance of the spatial aggregation of a univariate point process has been suggested by Diggle, Lange and Bene, (1991). We extend their replication-based approach to allow the comparison of the spatial interaction of two cell types between groups, to include planned comparisons (contrasts) and to assess whole groups against complete spatial randomness and spatial independence. We also accommodate several replicate tissue sections per subject. An advantage of our approach is that it can be applied when processes are not stationary, a common problem in brain tissue sections since neurons are arranged in cortical layers. We illustrate our methods by applying them to a neuropathological study to investigate abnormalities in the functional relationship between neurons and astrocytes in HIV associated dementia. (© 2004 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Influence of surgical technique and surface roughness on the primary stability of an implant in artificial bone with different cortical thickness: a laboratory studyCLINICAL ORAL IMPLANTS RESEARCH, Issue 2 2010Afsheen Tabassum Abstract Objective: The aim of this biomechanical study was to assess the interrelated effect of both surface roughness and surgical technique on the primary stability of dental implants. Material and methods: For the experiment, 160 screw-designed implants (Biocomp®), with either a machined or an etched surface topography, were inserted into polyurethane foam blocks (Sawbones®). As an equivalent of trabecular bone, a density of 0.48 g/cm3 was chosen. To mimic the cortical layer, on top of these blocks short-fibre-filled epoxy sheets were attached with a thickness varying from 0 to 2.5 mm. The implant sites were prepared using either a press-fit or an undersized technique. To measure the primary stability of the implant, both the insertion and the removal torques were scored. Results: Independent of the surgical technique used, both implant types showed an increased insertion and removal torque values with increasing cortical thickness, although >2 mm cortical layer no further increase in insertion torque was observed. In the models with only trabecular bone (without cortical layer) and with a 1 mm cortical layer, both implant types showed a statistically higher insertion and removal torque values for undersized compared with the press-fit technique. In addition, etched implants showed a statistically higher insertion and removal torque mean values compared with machined implants. In the models with 2 and 2.5 mm cortical layers, with respect to the insertion torque values, no effect of either implantation technique or implant surface topography could be observed. Conclusion: The placement of etched implants in synthetic bone models using an undersized preparation technique resulted in enhanced primary implant stability. A correlation was found between the primary stability and the cortical thickness. However, at or above a cortical thickness of 2 mm, the effect of both an undersized surgical approach, as also the presence of a roughened (etched) implant surface, had no extra effect. Besides the mechanical aspects, the biological effect of undersized drilling, i.e. the bone response on the extra insertion torque forces should also be elucidated. Therefore, additional in vivo studies are needed. To cite this article: Tabassum A, Meijer GJ, Wolke JGC, Jansen JA. Influence of surgical technique and surface roughness on the primary stability of an implant in artificial bone with different cortical thickness: a laboratory study. Clin. Oral Impl. Res. 21, 2010; 213,220. doi: 10.1111/j.1600-0501.2009.01823.x [source] | ||||||||||||||||||||||||||||