Die Forschungsergebnisse der letzten Jahre beweisen, dass die Informationsverarbeitung im ZNS auf eine ausgewogene Interaktion zwischen den Neuronen und den Astrozyten im Sinne eines funktionellen Netzwerkes angewiesen ist. Allerdings liegen nur unzureichende Erkenntnisse über den strukturellen Charakter dieser symbiotischen Beziehung vor. Zu den grundlegenden Aufgaben der Astrozyten gehört die Modulation der synaptischen Aktivität von Neuronen, Aufrechterhaltung der extrazellulären Homoöstase, Ausbildung der Blut-Hirn-Schranke, Pufferung der lokalen Kaliumkonzentration und die Synthese von Zytokinen, Wachstumsfaktoren sowie Neurotransmittern. Ein Hauptbestandteil des Zytoskelettes der Astrozyten stellen die Intermediärfilamente (z.B. GFAP, Vimentin) dar. Funktionell dienen sie dem Aufbau von Zell-Zell- Kontakten, der Stabilisierung des Zytoskelettes und der Verankerung der Zellorganellen im Zytoplasma. Charakteristisch für den strukturellen Aufbau der Astrozyten ist das GFAP, welches hauptsächlich in den Zellfortsätzen lokalisiert ist. Aktuelle Forschungen legen nahe, dass es sowohl unter physiologischen Alterungsprozessen als auch im Rahmen von pathologischen Vorgängen im ZNS (beispielsweise chronischer Alkoholabusus, Alexanderkrankheit, Ischämien und Epilepsie) zu einem prozentualen Anstieg der GFAP-Expression kommt, wobei der Einfluss dieser erhöhten GFAP-Synthese auf die Funktionsfähigkeit der Astrozyten noch nicht umfassend geklärt werden konnte. Im Zentrum dieser Dissertation steht deshalb die Fragestellung, haben Alter und Intermediärfilamente (GFAP, Vimentin) Einfluss auf Morphologie und Zellzahl der Astrozyten im Hippokampus einer Maus? Initial erfolgte die Volumenbestimmung der Astrozytendomänen mittels LSM- Aufnahmen im Reflexionsmodus sowie Vermessung nach Bearbeitung der Präparate mit der Silber Imprägnationstechnik. Die Domäne eines Astrozyten stellt das von einem Astrozyten mit Soma und allen Fortsätzen okkupierte Volumen dar. Nach der Auswahl von S100ß als immunhistochemischen Astrozytenmarker wurde die Zellzählung in entsprechenden Hippokampusarealen durchgeführt. Aus den ermittelten Daten wurde rechnerisch der Überlappungsgrad der hippokampalen Astrozytendomänen bestimmt. Von entscheidendem Interesse war dabei die Möglichkeit einer Überschneidung benachbarter Astrozytendomänen. Aus den Messungen resultiert ein ca 1,6 fach grösseres Volumen der Wildtyp-Tiere im Vergleich zu den Doppel-knock-out-Mäusen. Im Gegensatz dazu zeigten die Ergebnisse der Zellzählung sowohl in der Kontrollgruppe als auch in der Gruppe der Versuchstiere eine vergleichbare Astrozytenanzahl pro mm3. Entsprechend lag der Überlappungsfaktor bei den Doppel-Knock-out-Tieren (0,49) unter dem der Wildtyp-Tiere (0,7). Die abschließende Auswertung erbrachte in allen Untersuchungsgruppen einen Überlappungsfaktor < 1. Ausgehend von der essentiellen Bedeutung der Astrozyten für die Funktionsfähigkeit der Nervenzellen käme es z.B. im Rahmen pathologischer Prozesse, welche mit Gliazellschäden einhergehen, bei einem Überlappungsfaktor < 1 zu erheblichen Engpässen in der neuronalen Versorgung, sowie in der Kompensation äußerer Einflüsse. Die Wahrscheinlichkeit irreversibler Schädigung der Nervenzellen steigt.

No description available.

Organophosphates (OPs), including nerve agents, target the cholinergic system via inhibition of acetylcholinesterase (AChE), with subsequent overstimulation resulting in neural damage and potential detrimental long-term effects. The efficacy of novel pyridinium oxime reactivators, created with moieties to increase blood-brain barrier penetration, was tested using highly relevant sarin and VX surrogates. Glial fibrillary acidic protein (GFAP; an indicator of neural damage) and monoamines (dopamine, serotonin, and their metabolites) were measured in select brain regions via immunohistochemistry and HPLC, respectively. Adult male rats were treated ip with high, sub-lethal doses of surrogates for sarin or VX, nitrophenyl isopropyl methylphosphonate (NIMP) or nitrophenyl ethyl methylphosphonate (NEMP), respectively. Surrogate treatment was followed after 1 hr by im administration of novel oxime. Seizure activity was monitored, and kainic acid (KA) served as a positive control. Administration of KA or surrogate (NIMP or NEMP) significantly increased GFAP expression compared to control animals. Two different formulations of one particular oxime (bromide vs. mesylate salt) attenuated seizures and reduced GFAP levels over NIMP or NEMP treatments alone to levels near those of controls in both the piriform cortex and dentate gyrus region of the hippocampus, while 2-PAM did not provide protection. Serotonergic activity was increased in several brain regions, including the piriform cortex, one hr after NIMP treatment. Markers of oxidative stress (isoprostanes) were also tested. Overall, these results indicate the potential therapeutic efficacy of these oximes and suggest this innovative chemistry may protect against neural damage induced by OP.

No description available.

Previous studies of human oligodendroglial neoplasms have demonstrated the diagnostic and prognostic values of histomorphologic features and immunocytochemical markers. Primary spontaneous canine intracranial tumors share many of the biologic behaviors and pathologic features of their human counterparts. The objectives of this study were to determine if associations existed between five histomorphologic features (mitoses, cellular atypia, necrosis, vascular hypertrophy, and vascular proliferation), and three immunocytochemical markers (GFAP, EGFR, and Ki-67 labeling index) and the degree of malignancy, as defined by WHO grading criteria, of 15 canine oligodendroglial tumors. Of the histomorphologic variables examined, mitoses and cellular atypia were significantly greater in Grade III oligodendrogliomas than in Grade II oligodendrogliomas (p = 0.002, and p = 0.004, respectively), but no differences were noted between these features and Grade II oligoastrocytomas and Grade II or Grade III oligodendrogliomas. No significant associations were found between GFAP or EGFR immunoreactivity and tumor type or grade. The median percentage of Ki-67 immunoreactivity was significantly different between all tumor types and grades (p < 0.05), and was significantly higher in Grade III oligodendrogliomas than in both oligoastrocytomas (p = 0.014) and Grade II oligodendrogliomas (p = 0.006). Results of this study indicate that although mitoses and cellular atypia are useful histomorphologic features for the differentiation of tumors with oligodendroglial phenotypes, none of the variables examined reliably distinguished mixed gliomas from oligodendrogliomas. The presence of GFAP immunoreactivity in all tumor types suggests that oligodendroglial tumors may arise from a common multipotential cellular lineage. Similar to what has been demonstrated in humans, the Ki-67 labeling index correlated well with the degree of malignancy in the tumors studied. / Master of Science

Die Forschungsergebnisse der letzten Jahre beweisen, dass die Informationsverarbeitung im ZNS auf eine ausgewogene Interaktion zwischen den Neuronen und den Astrozyten im Sinne eines funktionellen Netzwerkes angewiesen ist. Allerdings liegen nur unzureichende Erkenntnisse über den strukturellen Charakter dieser symbiotischen Beziehung vor. Zu den grundlegenden Aufgaben der Astrozyten gehört die Modulation der synaptischen Aktivität von Neuronen, Aufrechterhaltung der extrazellulären Homoöstase, Ausbildung der Blut-Hirn-Schranke, Pufferung der lokalen Kaliumkonzentration und die Synthese von Zytokinen, Wachstumsfaktoren sowie Neurotransmittern. Ein Hauptbestandteil des Zytoskelettes der Astrozyten stellen die Intermediärfilamente (z.B. GFAP, Vimentin) dar. Funktionell dienen sie dem Aufbau von Zell-Zell- Kontakten, der Stabilisierung des Zytoskelettes und der Verankerung der Zellorganellen im Zytoplasma. Charakteristisch für den strukturellen Aufbau der Astrozyten ist das GFAP, welches hauptsächlich in den Zellfortsätzen lokalisiert ist. Aktuelle Forschungen legen nahe, dass es sowohl unter physiologischen Alterungsprozessen als auch im Rahmen von pathologischen Vorgängen im ZNS (beispielsweise chronischer Alkoholabusus, Alexanderkrankheit, Ischämien und Epilepsie) zu einem prozentualen Anstieg der GFAP-Expression kommt, wobei der Einfluss dieser erhöhten GFAP-Synthese auf die Funktionsfähigkeit der Astrozyten noch nicht umfassend geklärt werden konnte. Im Zentrum dieser Dissertation steht deshalb die Fragestellung, haben Alter und Intermediärfilamente (GFAP, Vimentin) Einfluss auf Morphologie und Zellzahl der Astrozyten im Hippokampus einer Maus? Initial erfolgte die Volumenbestimmung der Astrozytendomänen mittels LSM- Aufnahmen im Reflexionsmodus sowie Vermessung nach Bearbeitung der Präparate mit der Silber Imprägnationstechnik. Die Domäne eines Astrozyten stellt das von einem Astrozyten mit Soma und allen Fortsätzen okkupierte Volumen dar. Nach der Auswahl von S100ß als immunhistochemischen Astrozytenmarker wurde die Zellzählung in entsprechenden Hippokampusarealen durchgeführt. Aus den ermittelten Daten wurde rechnerisch der Überlappungsgrad der hippokampalen Astrozytendomänen bestimmt. Von entscheidendem Interesse war dabei die Möglichkeit einer Überschneidung benachbarter Astrozytendomänen. Aus den Messungen resultiert ein ca 1,6 fach grösseres Volumen der Wildtyp-Tiere im Vergleich zu den Doppel-knock-out-Mäusen. Im Gegensatz dazu zeigten die Ergebnisse der Zellzählung sowohl in der Kontrollgruppe als auch in der Gruppe der Versuchstiere eine vergleichbare Astrozytenanzahl pro mm3. Entsprechend lag der Überlappungsfaktor bei den Doppel-Knock-out-Tieren (0,49) unter dem der Wildtyp-Tiere (0,7). Die abschließende Auswertung erbrachte in allen Untersuchungsgruppen einen Überlappungsfaktor < 1. Ausgehend von der essentiellen Bedeutung der Astrozyten für die Funktionsfähigkeit der Nervenzellen käme es z.B. im Rahmen pathologischer Prozesse, welche mit Gliazellschäden einhergehen, bei einem Überlappungsfaktor < 1 zu erheblichen Engpässen in der neuronalen Versorgung, sowie in der Kompensation äußerer Einflüsse. Die Wahrscheinlichkeit irreversibler Schädigung der Nervenzellen steigt.

A Thesis submitted to The University of Arizona College of Medicine - Phoenix in partial fulfillment of the requirements for the Degree of Doctor of Medicine. / Epilepsy is the most common neurologic condition seen in children. Focal cortical dysplasia (FCD), a seizure disorder characterized by abnormal cortical laminar development, comprises approximately 75% of medically intractable epilepsies in the pediatric population. A greater appreciation of the pathology and intrinsic properties of the epileptogenic zone may help in understanding why FCD lesions are drug‐resistant, and could potentially lead to more effective treatments in the pediatric population. Neuronal support cells such as microglia and astrocytes have shown to have a role in FCD pathology. These cells are also activated during aging and traumatic brain injury as evidence by morphological change. This study aims to characterize the spatial distribution of microglia and astrocytes using immunohistochemistry in dysplastic tissue of eight male pediatric patients diagnosed with FCD. Cortical specimens from patients who underwent surgical resection of focally dysplastic cortex at Phoenix Children’s Hospital between 2008 and 2014 were examined using immunohistochemistry. Primary antibodies against GFAP and Iba1, as well as structural staining using hematoxylin and eosin (H&E), were incubated on sections and further analyzed using bright‐field microscopy. A pattern of perivascular activated microglia was observed in five patients around at least one blood vessel, while a pattern of non‐localized ramified microglia was observed in the other three patients. No identifiable pattern of astrocytic distribution was found. Thus, distinct patterns of microglia, rather than astrocytes, suggest dual underlying mechanisms of epileptogenesis.

Schwann cells (SCs) are crucial for peripheral nerve development and regeneration; however, the intrinsic regulatory mechanisms governing post-injury responses are poorly understood. Activation and deacetylation of nuclear factor-κB (NF- κB) in SCs have been implicated as prerequisites for peripheral nerve myelination. Using GFAP-IκBα-dn mice, in which NF- κB transcriptional activation is inhibited in SCs, we found no discernable differences in the quantity or structure of myelinated axons in adult facial nerves. Following crush injury, axonal regeneration was impaired at 31 days and greatly improved at 65 days in GFAP-IκBα-dn mutants. Compact re-myelination and sensory fiber organization were significantly compromised at 31 days and restored by 65 days. Together, these data indicate that NF- κB activation in SCs is dispensable for peripheral nerve myelination in adults, but required for early re-myelination and axonal regeneration. SC myelination during development and following injury in adult mice may hinge on different transcriptional cascades; these findings may offer new therapeutic avenues for PNS and CNS regeneration.

Olfactory ensheathing cells (OECs) are the chief glial population of the mammalian olfactory nervous system and are thought to be responsible for the successful directional growth of new olfactory axons throughout the life of adult mammals. Due to this unique property, OECs have been targeted as a potential cellular transplantation therapy for spinal cord injury. In order to effectively isolate OECs for intraspinal transplantation, more knowledge must be gained on their phenotypic properties. We investigated the neurochemical features of OECs in a variety of mammalian species (including hamsters, rabbits, monkeys, mice, and pigs) using three biomarkers: glial fibrillary acidic protein (GFAP), S100β, and α-smooth muscle actin (αSMA). In addition, we tested the ability of a few biomatrices to sustain and promote OEC growth and survival in vitro. The rationale for using biomatrices is to provide a supportive environment for glial and axonal growth in the spinal lesion. Here, we found that mucosal and bulbar OECs from all five of the aforementioned mammalian species express S100β. Expression of GFAP, however, was not consistent across the five species. Both mucosal and bulbar OECs of monkeys express αSMA; only bulbar OECs of hamsters and only mucosal OECs of rabbits express αSMA as well. Though αSMA immunostaining was not detected in the OECs of adult mice, in adult mutant mice lacking αSMA expression, OECs displayed perturbed ultrastructural morphology. None of the biomatrices used (methacrylated glycol chitosan, arginine-glycine-aspartic acid – grafted methacrylated glycol chitosan, and agarose) were able to promote OEC proliferation. Isolated strips of rodent olfactory lamina propria (the deep connective tissue layer in the olfactory mucosa containing primary sensory axons and OECs) showed sustained growth when cultured for 10 days. In sum, these findings highlight the following points: the efficacy of S100β and αSMA as biomarkers for mammalian OECs in vivo; the potential for isolated strips of lamina propria to provide a natural, supportive environment for OECs during intraspinal transplantation; the failure of methacrylated glycol chitosan and its derivatives, as well as agarose, to promote OEC proliferation. / Thesis (Master, Neuroscience Studies) -- Queen's University, 2012-07-27 15:29:47.642

BACKGROUND: Mild Traumatic Brain Injury (mTBI) is increasingly recognized as an adverse health consequence for athletes who participate in contact sports, such as football or boxing, as well as military personnel who are exposed to concussive blasts during training and combat operations. A consequence of this repetitive brain injury can be the development of a number of neurodegenerative diseases, particularly chronic traumatic encephalopathy (CTE), a disease involving the buildup of toxic phosphorylated tau (p-tau) in the pre-frontal cortical tissue. Additionally, it has been found that military personnel suffering repeated mTBI from primary blast concussions are prone to development of post traumatic stress disorder (PTSD), a disease that is becoming increasingly common among returning service members. Because mTBI is a common cause for both PTSD and CTE, it is possible for the two diseases to manifest comorbidly in an individual. Though much is known about PTSD psychologically and CTE neuropathologically, little is known about the overlapping effect of the two diseases together as well as PTSD neuropathologically. What is known, however, is that aquaporin-4; a channel involved in the movement of water through the blood brain barrier, is often affected by CTE and may play a role in PTSD as well. OBJECTIVE: The objective of this study was to primarily to analyze the disruption of aquaporin-4 around cerebral blood vessels due to chronic traumatic encephalopathy. A secondary objective of this project was to determine if any unique physiopathological biomarkers exist in PTSD and if the effects of CTE are exacerbated when present comorbidly with PTSD. METHODS: This study involved the analysis of multiple cohorts that had suffered from CTE, PTSD and CTE comorbidly, or neither disease as a control. In order to assess the primary objective, two cohorts, a CTE-only and a control, were analyzed to determine the effect of p-tau on aquaporin-4 directly around cerebral vessels in the pre-frontal cortex. The samples were cut from blocks and stained for the desired markers. Following staining, images were taken using a confocal microscope and the images were analyzed using Amaris and FIJI. For the secondary objective, samples were prepared in a similar way with three cohorts: CTE-only, CTE+PTSD comorbid, and a control. Images were obtained and processed in the same way. RESULTS: It was found that aquaporin-4 density is significantly reduced around both arterial and venous lesional vessels. Additionally, it was found that p-tau was more readily deposited in the depths of the sulci of the pre-frontal cortex due to the unique forces caused by repeated mTBI. However, PTSD was not found to significantly compound the disease when comorbidly present with CTE nor to have a unique biomarkers present. CONCLUSION: P-tau present in CTE causes a significant reduction in aquaporin-4 around cerebral vessels in the pre-frontal cortex, thereby potentially inhibiting the movement of fluids and clearance of metabolites into and out of the brain. Additionally, p-tau is more readily deposited in the depths of the sulci of the pre-frontal cortex. However, PTSD does not compound the CTE disease process when comorbidly present. / 2018-07-13T00:00:00Z