Calcium signaling in neurogenesis: regulation of proliferation, differentiation and migration of neural stem cells

The calcium ion (Ca2+) is a highly versatile and ubiquitous signaling messenger in all cell types. Signal transduction occurs through changes in the cytosolic Ca2+ concentration after the opening of Ca2+ channels in the plasma membrane (PM) and endoplasmic reticulum (ER). The difference in Ca2+ concentration between the extracellular space and the cytosol is large, around 10,000 fold, creating a steep gradient that causes Ca2+ to rapidly flow into the cell. Signaling via Ca2+ is fundamental for triggering numerous vital processes in the cell, ranging from fertilization to cell death. Calcium signaling is also critical for regulating neurogenesis in various ways, some of which have been explored in this work. Proliferation of neural progenitors is dependent on spontaneous Ca2+ activity that occurs in small-scale networks. Ca2+ activity is correlated with electrical activity both in vitro and in vivo and depends on connexin 43 gap junction and PM channels. Differentiation of neural progenitors is also regulated by Ca2+ signaling. We have found that T α1h voltage-dependent Ca2+ channels promote spontaneous Ca2+ activity and direct the differentiation of human neuroepithelial stem cells towards neurons, depending on caspase-3 enzymatic activity. These results were confirmed with T α1h knockout mice that showed a decreased number of neurons in the dorsal cortex. Neuronal migration also depends on Ca2+ signaling. We demonstrated that glial derived neurotrophic factor (GDNF) stimulates a Ca2+ response through the activation of the receptor tyrosine kinase (RET). The subsequent downstream signaling cascade includes phospholipase Cγ, which binds to RET Tyr1015. Mutating RET at Tyr1015 inhibits neuronal progenitor migration towards the cortical plate. We also showed that neurogenesis was altered by the addition of non-cytotoxic concentrations of polychlorinated biphenyls that disrupt spontaneous Ca2+ activity. Polychlorinated biphenyls are common food contaminants. In addition, methyl mercury, another food contaminant, disrupts neuronal differentiation in the opposite direction. Altogether, these data demonstrate the huge impact of Ca2+ signaling on the development of the embryonic brain. To conclude, we have analyzed Ca2+ signaling during three critical steps of neurogenesis: proliferation, differentiation, and migration. All of these processes are known to be dependent on Ca2+. A deeper understanding of how Ca2+ regulates such different physiological processes is crucial for the field of regenerative medicine, in which control of the expansion and differentiation of neural stem cells can increase the production of neuronal cells in vitro for use in cell replacement therapies

Perfluorooctane sulfonate induces neuronal and oligodendrocytic differentiation in neural stem cells and alters the expression of PPARγ in vitro and in vivo

Perfluorinated compounds are ubiquitous chemicals of major concern for their potential adverse effects on the human population. We have used primary rat embryonic neural stem cells (NSCs) to study the effects of perfluorooctane sulfonate (PFOS) on the process of NSC spontaneous differentiation. Upon removal of basic fibroblast growth factor, NSCs were exposed to nanomolar concentrations of PFOS for 48 h, and then allowed to differentiate for additional 5 days. Exposure to 25 or 50 nM concentration resulted in a lower number of proliferating cells and a higher number of neurite-bearing TuJ1-positive cells, indicating an increase in neuronal differentiation. Exposure to 50 nM also significantly increased the number of CNPase-positive cells, pointing to facilitation of oligodendrocytic differentiation. PPAR genes have been shown to be involved in PFOS toxicity. By q-PCR we detected an upregulation of PPARγ with no changes in PPARα or PPARδ genes. One of the downstream targets of PPARs, the mitochondrial uncoupling protein 2 (UCP2) was also upregulated. The number of TuJ1- and CNPase-positive cells increased after exposure to PPARγ agonist rosiglitazone (RGZ, 3 μM) and decreased after pre-incubation with the PPARγ antagonist GW9662 (5 μM). RGZ also upregulated the expression of PPARγ and UCP2 genes. Meanwhile GW9662 abolished the UCP2 upregulation and decreased Ca2 + activity induced by PFOS. Interestingly, a significantly higher expression of PPARγ and UCP3 genes was also detected in mouse neonatal brain after prenatal exposure to PFOS. These data suggest that PPARγ plays a role in the alteration of spontaneous differentiation of NSCs induced by nanomolar concentrations of PFOS

Jaw osteonecrosis after dental implants associated with oral bisphosphonates – case report of resection of mandible

Osteonecrosis of the jaw is associated with defects in vascularization and with the use of oral bisphosphonates. Osseous exposition and infection may occur. Recommended treatment is variable, from antibiotic medication, bony decortication to resections of the mandible in severe cases. Reconstruction of mandible, in cases of resections is essential for maintaining esthetic profile and adequate form and function. Objective: To report a case about the dangers oforal bisphosphonates in association with invasive procedures such as dental implants Case report: Female patient, 64 years-old, with osteonecrosis of the jaw caused by use of oral bisphosphonates after rehabilitation with dental implants. She had an edentulous and atrophic mandible and poor healthy. After diagnosis, partial resection of the jaw was performed together with the reconstruction with titanium plate, with no success. Then, iliac bone graft fixed by plates and screws was attempted, again with no success. Conclusion: Despiteof the small number of cases of osteonecrosis associated with oral bisphosphonate reported in the literature, a simple implant surgery could result in adverse consequences if the use of this medication were overlooked in the anamnesis.Osteonecrosis of the jaw is associated with defects in vascularization and with the use of oral bisphosphonates. Osseous exposition and infection may occur. Recommended treatment is variable, from antibiotic medication, bony decortication to resections of the mandible in severe cases. Reconstruction of mandible, in cases of resections is essential for maintaining esthetic profile and adequate form and function. Objective: To report a case about the dangers oforal bisphosphonates in association with invasive procedures such as dental implants Case report: Female patient, 64 years-old, with osteonecrosis of the jaw caused by use of oral bisphosphonates after rehabilitation with dental implants. She had an edentulous and atrophic mandible and poor healthy. After diagnosis, partial resection of the jaw was performed together with the reconstruction with titanium plate, with no success. Then, iliac bone graft fixed by plates and screws was attempted, again with no success. Conclusion: Despiteof the small number of cases of osteonecrosis associated with oral bisphosphonate reported in the literature, a simple implant surgery could result in adverse consequences if the use of this medication were overlooked in the anamnesis

IMPACTO DA CIRURGIA ORTOGNÁTICA SOBRE A QUALIDADE DE VIDA DE PACIENTES ATENDIDOS NO SERVIÇO DA UNIVERSIDADE FEDERAL DO PARANÁ

A qualidade de vida vem sendo discutida e estudada cada vez mais nos últimos anos quando falamos em saúde, abrindo um leque para o estudo dos impactos que ela pode vir a trazer. A preocupação com a técnica nos procedimentos odontológicos começa a ser percebida de um novo ponto de vista, com maior enfoque no ser humano como um todo. Tendo em mente uma nova concepção de saúde,  o “The Oral Health Impact Profile”  (OHIP) é usado como intrumento para avaliar o impacto de problemas bucais no indivíduo, abrangendo as dimensões física, psicológica e social da vida diária. O OHIP14, versão resumida do OHIP, foi publicado por Slade em 1997. Este estudo, realizado na Universidade Federal do Paraná, avaliou o impacto na qualidade de vida dos pacientes submetidos a cirurgia ortognática a partir do uso desse questionário. O estudo mostrou um impacto negativo na qualidade de vida maior nos indivíduos que apresentam deformidades dentofaciais do que naqueles que não apresentam

Surgical treatment of mandibular condyle fracture with bicortical screws: case report

Mandibular condyle fractures are, of all facial fractures, those with the greatest controversies in relation to its conduct. Patient systemic condition, location and displacement degree of the fracture, mouth opening amplitude, and occlusion alteration are some factors that influence on the decision on conservative or surgical treatment. Pain, mandibular movement limitation, altered dental occlusion, and facial asymmetry are signs and symptoms that indicate condylar fracture. The surgical treatment consists of surgical fracture reduction and subsequent fixing through titanium miniplates and\or screws. Objective: The aim of this study was to report the case of a patient who had parasymphyseal fracture associated with left mandibular condyle fracture, presenting limited excursive movements of the jaw, pain in function, altered dental occlusion, and bruising on chin region. Case report: Due to the type of fracture and patient systemic condition, we decided to open reduction of fractures and stable internal fixation. Conclusion: At 12-month follow-up, the patient showed significant improvement in both clinical and functional condition, demonstrating the effectiveness of the treatment method and techniqu

Central giant cell granuloma (CGCG) in childhood: surgical treatment by maintaining the tooth germs

Introduction: Central Giant Cell Granuloma (CGCG) is a nonneoplasticbenign process, of unknown etiology, more common in children and young adults. When aggressive, the lesion may result in considerable bone destruction and deformation. Oral and Maxillofacial surgery strongly depends on the nature of injury and it may vary from more conservative to more aggressive approach. Case report: The aim of the present study is to report and analyze, a giant cellcentral lesion in a 7-year-old patient on the right side of mandible body treated by surgical enucleation, curettage, and maintenance of the tooth germs. Discussion: In less aggressive lesions, curettage followed by radiographic monitoring is the most widely suggested treatment choice. However, the “gold standard” for aggressive and deforming lesions would be en-bloc resection with a safety margin. Most revisions show recurrence rates of 15 to 20%, thus clinicalmonitoring is necessary at least one year after the intervention. Conclusion: After 12 months, panoramic radiograph and computed tomography indicated new bone formation and no recurrence. In addition, good healing of soft tissues and correct eruption of the teeth #42, #43 and #44 were observed.Introduction: Central Giant Cell Granuloma (CGCG) is a nonneoplasticbenign process, of unknown etiology, more common in children and young adults. When aggressive, the lesion may result in considerable bone destruction and deformation. Oral and Maxillofacial surgery strongly depends on the nature of injury and it may vary from more conservative to more aggressive approach. Case report: The aim of the present study is to report and analyze, a giant cellcentral lesion in a 7-year-old patient on the right side of mandible body treated by surgical enucleation, curettage, and maintenance of the tooth germs. Discussion: In less aggressive lesions, curettage followed by radiographic monitoring is the most widely suggested treatment choice. However, the “gold standard” for aggressive and deforming lesions would be en-bloc resection with a safety margin. Most revisions show recurrence rates of 15 to 20%, thus clinicalmonitoring is necessary at least one year after the intervention. Conclusion: After 12 months, panoramic radiograph and computed tomography indicated new bone formation and no recurrence. In addition, good healing of soft tissues and correct eruption of the teeth #42, #43 and #44 were observed

RET PLCγ Phosphotyrosine Binding Domain Regulates Ca2+ Signaling and Neocortical Neuronal Migration

The receptor tyrosine kinase RET plays an essential role during embryogenesis in regulating cell proliferation, differentiation, and migration. Upon glial cell line-derived neurotrophic factor (GDNF) stimulation, RET can trigger multiple intracellular signaling pathways that in concert activate various downstream effectors. Here we report that the RET receptor induces calcium (Ca2+) signaling and regulates neocortical neuronal progenitor migration through the Phospholipase-C gamma (PLCγ) binding domain Tyr1015. This signaling cascade releases Ca2+ from the endoplasmic reticulum through the inositol 1,4,5-trisphosphate receptor and stimulates phosphorylation of ERK1/2 and CaMKII. A point mutation at Tyr1015 on RET or small interfering RNA gene silencing of PLCγ block the GDNF-induced signaling cascade. Delivery of the RET mutation to neuronal progenitors in the embryonic ventricular zone using in utero electroporation reveal that Tyr1015 is necessary for GDNF-stimulated migration of neurons to the cortical plate. These findings demonstrate a novel RET mediated signaling pathway that elevates cytosolic Ca2+ and modulates neuronal migration in the developing neocortex through the PLCγ binding domain Tyr1015

Recombinant Spider Silk Protein Matrices Facilitate Differentiation of Neural Stem Cells Into Mature and Functional Neurons

Neural stem cells (NSCs) show great promise in drug discovery and clinical application. Yet few efforts have been made to optimize biocompatible materials for such cells to be expanded and used in clinical conditions. We have previously demonstrated that NSCs are readily cultured on substrates of certain recombinant spider silk protein without addition of animal- or human-derived components. The question remains however whether this material allows differentiation into functional neurons, and whether such differentiation can take place also when the NSCs are cultured not only upon but also within the biodegradable material. Here we demonstrate that "foam"-like structures generated from recombinant spider silk protein (4RepCT) provided excellent matrices for the generation and multicellular analysis of functional excitatory neurons from NSCs without addition of animal- or human-derived components. NSCs isolated from the cerebral cortices of rat embryos were cultured at either 4RepCT matrices shaped as foam-like structures without coating, or on conventional polystyrene plates coated with poly-L-ornithine and fibronectin. Upon treatment with recombinant proteins including the extracellular signaling factor BMP4 or a combination of BMP4 and the signaling factor Wnt3a, the cortical NSCs cultured in 4RepCT foam-like structures differentiated efficiently into neurons that responded to glutamate receptor agonists, such as AMPA, to the same extent as control cultures. Matrices derived from recombinant spider silk proteins thus provide a functional microenvironment for neural stem cells with little or no animal- or human-derived components and can be employed in the development of new strategies in stem cell research and tissue engineering

Isotopic resonance at 370 ppm deuterium negatively affects kinetics of luciferin oxidation by luciferase

Since 1930s, it has been known that some biochemical and biological processes exhibit abnormal kinetics at a deuterium concentration in the local environment of 250-600 ppm, which is 2-4 times higher that the normal concentration of 150 ppm D. We sought to test if the kinetics of firefly luciferase oxidizing luciferin, the reaction widely used as a read-out in various biochemical assays, is also affected by an elevated deuterium content. To this end, both luciferase and luciferin substrate solutions were prepared based on water with extra deuterium added to a concentration ranging from 150 ppm and up to 10,000 ppm (1%). Upon mixing the solutions, the luminescence intensity at different times was compared with that of the corresponding control solutions with 150 ppm D. A broad negative resonance was detected (p < 10(-6)), with a approximate to 20% drop in luminescence at 370 ppm D. Given that, on average, about half of hydrogen atoms in proteins are not exchangeable in solution, this value corresponds to approximate to 260 ppm of deuterium in all enzyme's hydrogens, in a very good agreement with the prediction of the Isotopic resonance hypothesis