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  • 1
    Keywords: Medicine ; Human Physiology ; Neurosciences ; Pathology ; Rehabilitation ; Sports Medicine ; Biomedicine ; Neurosciences ; Human Physiology ; Pathology ; Sports Medicine ; Rehabilitation ; Biomedicine general ; Springer eBooks
    Description / Table of Contents: Historical perspectives in understanding traumatic brain injury and in situating disruption in CBF in the pathotrajectory of head trauma -- Situating Cerebral Blood Flow in the Pathotrajectory of Head Trauma -- Modeling of traumatic brain injury and its implications in studying the pathology of repeated mild impacts to the head -- The presence of venous damage and microbleeds in traumatic brain injury and the potential future role of angiographic and perfusion magnetic resonance imaging -- Situating the Endothelin System in the pathotrajectory of TBI-induced changes in haemodynamics -- Age and Sex Differences in Cerebral Blood Flow and Autoregulation after Pediatric Traumatic Brain Injury -- New Frontiers in Clinical Trials Aimed at Improving Outcome Following Traumatic Brain Injury
    Abstract: 〈p〉Traumatic brain injury (TBI) has caught the ear of the general public in the last few years in the context of injuries seen both in athletes and the military.℗ Despite TBI being situated as a critical problem in society for multiple decades, the underlying pathotrajectory of TBI has only recently been truly appreciated.℗ Only recently has TBI research begun to develop better models of TBI that more closely recapitulate the human condition, make new advances in our ability to image pathophysiological sequelae in the brain following TBI, place a greater emphasis on studying the vascular dysfunction that accompanies head trauma, and, very recently, explore a new understanding of how age and sex can alter outcome to brain injury.〈/p〉〈p〉While this book was developed to satisfy a wide audience, from patient to caregiver, basic scientist to clinical scientist, the overall goal is to present the most current information known about head trauma and to expose areas where we may be deficient in understanding the nuances of TBI.℗ ℗ In particular, focus will be placed on the largest gap in our knowledg途the influence of cerebral blood flow (CBF) and metabolism in outcome following injury. This volume explores such varied concepts as the influence of CBF in the pathotrajectory of TBI, modeling TBI as a means to understand underlying pathological states associated with brain injury victims, disrupted vasculature following head trauma and advanced imaging techniques, vasoreactive substances underlying disrupted blood flow, the role of age and sex on injury outcome, and the latest pre-clinical rationale for focusing on CBF and strategies to improve blood flow as a means to improve outcome in patients suffering the effects of TBI.℗ Taken together, the information contained in ́€œCerebral Blood Flow, Metabolism, and Head Traumဝ is designed to both educate and illuminate anyone associated with TBI, with the hopes of stimulating future research.〈/p〉
    Pages: : digital.
    ISBN: 9781461441489
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  • 2
    ISSN: 1432-0533
    Keywords: Cerebral ischemia ; Lipid peroxidation ; Pathology ; Reperfusion
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Rats were subjected to cardiac arrest and resuscitation, 90 min of reperfusion, and in situ perfusion fixation. Thiobarbituric acid (TBA) was included in the aldehyde-free perfusion fixative, the TBA reaction was driven in situ by heating, and fluorescence microscopy was utilized to characterize the location of products of the TBA reaction. Absorbance-difference spectra were performed on butanol-extracted brain homogenates to confirm in situ formation of TBA adducts with aldehydic products of lipid peroxidation. Nissl-stained sections revealed good cellular fixation without shrinkage artifacts. Fluorescence was not seen microscopically when TBA was omitted from the perfusion fixative, and little fluorescence was present in normal brains or brains after ischemia only. However, after 90-min reperfusion, intense granular fluorescence was seen in the neuronal perikarya (especially at the base of the apical dendrite) of numerous pyramidal neurons in cortical layers 5 and 6 and in the pyramidal layer of Ammon's horn in the hippocampus. The nuclei of these cells exhibited no fluorescence. Fluorescence was also present in some striatal neurons, but was absent in the adjacent radial bundles. Neither glia nor white matter exhibited similar fluorescence. These observations indicate that neurons in the selectively vulnerable zones of the cortex and hippocampus are early and specific targets of lipid peroxidation during post-ischemic reperfusion.
    Type of Medium: Electronic Resource
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  • 3
    ISSN: 1432-0533
    Keywords: Cerebral ischemia ; Reperfusion injury ; Golgi apparatus ; Endoplasmic reticulum
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract The neocortex and the hippocampus were examined for lipid peroxidation products and ultrastructural alterations by fluorescence and electron microscopy, respectively, in rats subjected to 10 min of cardiac arrest or 10 min cardiac arrest and either 90 or 360 min reperfusion. Lipid peroxidation products were observed after 90 min reperfusion in the perikarya and proximal dendrites of neocortical pyramidal neurons and in the hippocampal hilar cells and CA1, region; the fluorescene was most intense at the base of the apical dendrite, the region of the Golgi apparatus. After 90 min of reperfusion, the CA1, showed considerable stretches of rough endoplasmic reticulum devoid of ribosomes and the Golgi cisternae were shorter and widely dilated. The neocortex showed similar endoplasmic reticulum changes, but no significant alterations to the Golgi were noted. In addition there were areas where strings of ribosomes appear to be detaching from the endoplasmic reticulum. After 360 min reperfusion in both the neocortex and the hippocampus, the damage appeared more severe. The Golgi was fragmented into vacuoles, membranous whorls had appeared, and dense aggregates of smooth vesicles were seen coalescing with each other and the vacuoles. These observations suggest that early Golgi involvement is a more important marker of lethal injury than ribosome release from the endoplasmic reticulum. The areas of disturbed Golgi ultrastructure correspond to those areas that show evidence of lipid peroxidation and imply that lipid peroxidation may be causally related to the disturbance in Golgi ultrastructure.
    Type of Medium: Electronic Resource
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  • 4
    ISSN: 1432-0533
    Keywords: Key words Ischemia ; Protein synthesis ; Translation ; Ultrastructure ; Hippocampus
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract During post-ischemic brain reperfusion there is a substantial reduction of protein synthesis in selectively vulnerable neurons. Normal protein synthesis requires a functional translation initiation complex, a key element of which is eukaryotic initiation factor 2 (eIF2), which in a complex with GTP introduces the met-tRNAi. Phosphorylation of Ser51 on the α subunit of eIF2 [eIF2α(P)] generates a competitive inhibitor of eIF2B, thereby preventing the replenishment of GTP onto eIF2, thus blocking translation initiation. It has been shown that the conditional expression of an eIF2α mutant (Asp substituted for Ser51) imitating the negative charge of Ser51 (P) induces apoptosis. During the first 10 min of post-ischemic reperfusion, there is an approximately 20-fold increase in eIF2α(P) seen in the cytoplasm of CA1 hippocampal neurons, and, by 1 h, there is also accumulation of eIF2α(P) in the nucleus. We utilized post-embedding electron microscopical immunogold methods to examine the localization of eIF2α(P) during reperfusion. Immunogold particles (10 nm) were concentrated chiefly along the rough endoplasmic reticulum and in association with the membranes of the nuclear envelope in CA1 neurons. Aggregations of gold particles in the nucleus were concentrated: (1) within and around the nucleolus, (2) associated to strands of heterochromatin, and (3) along putative nuclear filaments. The presence of eIF2α(P) in the nucleolus probably reflects its association with nascent ribosomal subunits. The β-subunit of eIF2 has a zinc finger and polylysine blocks analogous to those on other proteins that affect transcription. The association of eIF2α(P) with chromatin may have important implications for transcription.
    Type of Medium: Electronic Resource
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  • 5
    ISSN: 1432-0533
    Keywords: Key words Reperfusion ; Cerebral blood flow ; Vascular smooth muscle cell ; Pericyte ; Scanning ; electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract The present study was undertaken to ascertain the role of smooth muscles and pericytes in the microcirculation during hyperperfusion and hypoperfusion following ischemia in rats. Paired external carotids, the pterygopalatine branch of the internal carotids and the basilar artery were exposed and divided. Reversible inflatable occluders were placed around the common carotids. After 24 h, the unanesthetized rat underwent 10-min ischemia by inflating the occluders. Continuous cortical cerebral blood flow (c-CBF) was monitored by laser Doppler flowmetry. The measured c-CBF was below 20% of control (P 〈 0.001) during ischemia. A c-CBF of 227.5 ± 54.1% (P 〈 0.001) was obtained during reperfusion hyperemia. A c-CBF of 59.7 ± 8.8% (P 〈 0.001) occurred at the nadir of postischemic hypoperfusion, and this was followed by a second hyperemia. The cytoarchitecture of the vascular smooth muscles and pericytes was assessed by scanning electron microscopy. Samples were prepared using a KOH-collagenase digestion method. In control rats, arteriolar muscle cells showed smooth surfaces. Capillary pericytes were closely apposed to the endothelium. Immediately after reperfusion, transverse membrane creases were observed on the smooth muscle surfaces. During maximal hyperemia the creases disappeared. When c-CBF started to decrease the creases became visible again. Throughout the postischemic hypoperfusion the creases remained. Capillary endothelial walls became tortuous in the late phase of hypoperfusion. During the second hyperemia most arteriolar muscle cells showed smooth surfaces. Some pericytes appeared to have migrated from the vascular wall. The morphological changes of smooth muscle membranes suggest that they are related to specific perfusional disturbances during ischemia and reperfusion.
    Type of Medium: Electronic Resource
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  • 6
    ISSN: 1432-0533
    Keywords: Key words Radicals ; Neuron ; Ultrastructure ; Differentiation ; Golgi
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract There is abundant evidence that the pathophysiology leading to neuronal death during post-ischemic brain reperfusion involves radical-mediated damage. Although the ultrastructural alterations accompanying brain ischemia and reperfusion are well characterized, little is known about the ultrastructural alterations that are specific to radical damage. This study examines in differentiated and undifferentiated neuroblastoma B-104 cells the viability (by dye exclusion) and ultrastructural consequences of radical damage initiated by 50 μM cumene hydroperoxide (CumOOH). Differentiation was most notably associated with formation of neurites and an extensive cytoskeletal feltwork. CumOOH-induced cell death was increased after differentiation and was blocked by the iron chelator DETAPAC. The ultrastructural characteristics of radical damage here included: (1) plasmalemmal holes that appear to undergo “patching” by well-organized membrane whorls, (2) accumulation of numerous free ribosomes, (3) markedly increased vesicular trafficking about the Golgi accompanied by Golgi transformation from cisternal organization to clusters of vacuoles with numerous fusing vesicles, (4) development of large multi-layered vacuoles that include damage membranes and organelles and appear to undergo extrusion from the cell, and (5) a general loss of cytoplasmic volume. These ultrastructural alterations developed more rapidly and were consistently more advanced in differentiated cells throughout the 6-h time course. In differentiated cells radical damage also induced the disorganization and subsequent loss of the extensive feltwork of cytoskeletal elements. There was little damage to the membranes of the nuclear envelope and mitochondria. Our observations in this system are strikingly similar to ultrastructural alterations in Golgi and ribosomal organization seen in vulnerable neurons during post-ischemic brain reperfusion and suggest that these alterations during reperfusion reflect the consequence of radical-mediated damage.
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  • 7
    ISSN: 1749-6632
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Natural Sciences in General
    Type of Medium: Electronic Resource
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  • 8
    ISSN: 1573-7381
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Although light microscopic studies have analysed phrenic motor neurons in several different species, there has never been an ultrastructural investigation of identified phrenic motor neurons. In addition, electrophysiological studies have raised questions relating to the function of phrenic motor neurons which may be answered only by direct electron microscopic investigation. Thus, the present study was carried out to provide a detailed ultrastructural analysis of identified phrenic motor neurons. Phrenic motor neurons in the spinal cord of the rat were labelled by retrogradely transported horseradish peroxidase (HRP) after transecting the phrenic nerve in the neck and applying the enzyme directly to the central stump of the transected nerve. The results showed that the general ultrastructural characteristics of phrenic motor neurons were similar to those previously reported for other spinal motor neurons. However, phrenic primary dendrites appeared to be isolated from all other dendritic profiles in the neuropil. Primary dendrites were not fasciculated. Fasciculation occurred only among the more distal secondary and tertiary phrenic dendritic branches. Direct dendrodendritic or dendrosomatic apposition was rarely seen; gap junctions between directly apposing phrenic neuronal membranes were not observed. The membranes of adjacent phrenic neuronal profiles were most frequently separated by intervening sheaths of astroglial processes. Myelinated phrenic axons and a phrenic axon collateral were identified. The initial portion of the phrenic axon collateral was cone-shaped, lacked myelin, and thus resembled a miniature axon hillock. In one instance, a large accumulation of polyribosomes was observed within the hillock-like structure of a phrenic axon collateral. Eight morphological types of synaptic boutons, M, P, NFs, S, NFf, F, G and C were classified according to criteria used by previous investigators. Most of these endings (M, NFs, NFf, S and F) made synaptic contact with profiles of labelled phrenic somata and dendrites. F, NFf, and S boutons also terminated on phrenic axon hillocks. C and G boutons contacted exclusively phrenic somata and small calibre dendrites, respectively. P boutons established axo-axonic synaptic contacts with the M and NFs bouton. The morphological findings of the present study provide new data that may be related to phrenic synchronized output and presynaptic inhibition of primary afferents terminating on phrenic motor neurons.
    Type of Medium: Electronic Resource
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  • 9
    ISSN: 0003-276X
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: The morphological characteristics of olfactory receptor neurons and their relations to the sustentacular cells and to the sheath cells of Schwann in the olfactory mucosa of the salamander (Ambystoma maculatum et tigrinum) were studied using a modification of the rapid Golgi technique. The bipolar receptor neurons had a fusiform-shaped cell body whose apical pole gave rise to a surface-reachig dendrite and a basal pole which gave rise to an axon. The length and width of the dendrite, although variable, were positively correlated with the relative depth at which the cell body was located in the sensory epithelium. Beyond the initial segment, the axon had a sinuos course prior to its entrance into the lamina propria. Within the lamina propria, the axons were associated with the sheath cells of Schwann to for the olfactory nerve fascicles. The processes of adjacent sheath cells formed an elaborate network of continous cavities through which the axons coursed.Two morphologically distinct varieties of sustentacular cells, designated types I and II, were found in the sensory epithelium. Both types had a columnar profile cnsisting of an elongated cell body, a central stalk, and a basilar expansion of the stalk found at the junction of the epithelium with the lamina propria. The central stalk of type I sustentacular cells was unbranched, whereas that of type II cells gave rise to riblike processes from which cytoplasmic veils extended to envelop the cell bodies of receptor neurons. The basilar expansions were found in close apposition to the wall of capillaries or to acinar cells of Bowman's glands located in the most superficial region of the lamina propria. The morphological relationships and possible interdependencies among receptor neurons, the types of sustentacular cells, and the sheath cells are discussed.
    Additional Material: 15 Ill.
    Type of Medium: Electronic Resource
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  • 10
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    The @Anatomical Record 211 (1985), S. 75-86 
    ISSN: 0003-276X
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: In Golgi impregnated transverse sections through the cervical spinal cord of the 7-12-week-old adult rat, numerous tanycytes were observed radiating from the ependyma into the gray matter that surrounds the central canal. The tail processes of these tanycytes terminated as foot processes in association with blood vessels. Spinal tanycytes were classified into ependymal (E) and subependymal (S) types on the basis of the shape and position of the soma. The soma of the E tanycyte was shaped as a column and was entirely located within the ependyma. In contrast, the soma of the S tanycyte was flask shaped, with the widest portion of the flask located subependymally and the elongated portion extending through the ependyma ultimately reaching the luminal surface. Selected Golgi impregnated sections were gold toned and deimpregnated for direct correlative analysis at the ultrastructural level. Gold-toned tanycytes contained the fine clusters of gold particles underlying the plasma membrane of the cell body and coarse clusters of gold particles throughout the tail and foot processes. The apical surface of tanycytes was characterized by numerous microvilli and large cytoplasmic protrusions that evaginated from the apical surface into the lumen of the central canal. At the luminal surface, adjacent tanycytes were joined laterally by junctional complexes with punctate tight junctions and zonulae adhaerentes associated with fibrils and microtubules. In contrast, gap junctions, hemidesmosomes, and puncta adhaerentia were found between adjacent tail processes of tanycytes. The foot processes interdigitated with one another and abutted the basal lamina around the perivascular space of blood vessels. The basal lamina was continuous around the lateral walls of foot processes and filled the spaces between membranous infoldings of the lateral walls. These basal membrane labyrinths were continuous with the basal lamina of the blood vessel and may provide an extensive surface relation between the perivascular space and the neighboring extracellular compartment. The findings of the present study support the contention that tanycytes may modify the composition of substances moving between the perivascular and extracellular spaces.
    Additional Material: 22 Ill.
    Type of Medium: Electronic Resource
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