Optimal tooth sectioning using a surgical handpiece and elevator: a finite element study of horizontally deeply impacted mandibular third molars.

OBJECTIVES: To conduct a finite element analysis of the impact of different variables on tooth sectioning efficiency and trauma to surrounding tissues when utilizing high-speed surgical handpieces and elevators. METHODS: CBCT data from the horizontally impacted third mandibular molar (M3M) of a patient were utilized to establish digital models of the M3M, adjacent M2M, and surrounding bone. To simulate tooth sectioning, a 3D finite element model was established with the following variables: remaining tooth tissue thickness (1-5 mm), tooth section fissure width (1-3 mm), elevator depth in fissure (2-6 mm), elevator position (buccal, lingual, central), elevator width (2-5 mm), and application of force (rotating, levering). Using this model, the distribution of stress on the M3M and the surrounding tissue was assessed while measuring tooth sectioning efficiency and trauma to the surrounding tissue. RESULTS: Factors associated with uniform stress at the site of sectioning included thin (≤ 3 mm) remaining tooth tissue, appropriate fissure width (~ 2 mm), a wide (≥ 4 mm) elevator, and central elevator positioning. Levering the elevator yielded greater stress on the M3M than rotating force. Greater sectioning efficiency was associated with increased stress placed on the distobuccal side of M2M. CONCLUSIONS: Tooth sectioning efficiency can be improved by adjusting the high-speed surgical handpiece and elevator. However, it is important to remain attentive to the trauma to which adjacent teeth are exposed during this process. CLINICAL SIGNIFICANCE: These results offer guidance for approaches to improving operator efficiency and reducing trauma to surrounding tissues during tooth sectioning.

Deep-computer-generated holography with temporal-focusing and a digital propagation matrix for rapid 3D multiphoton stimulation.

Deep learning-based computer-generated holography (DeepCGH) has the ability to generate three-dimensional multiphoton stimulation nearly 1,000 times faster than conventional CGH approaches such as the Gerchberg-Saxton (GS) iterative algorithm. However, existing DeepCGH methods cannot achieve axial confinement at the several-micron scale. Moreover, they suffer from an extended inference time as the number of stimulation locations at different depths (i.e., the number of input layers in the neural network) increases. Accordingly, this study proposes an unsupervised U-Net DeepCGH model enhanced with temporal focusing (TF), which currently achieves an axial resolution of around 5 µm. The proposed model employs a digital propagation matrix (DPM) in the data preprocessing stage, which enables stimulation at arbitrary depth locations and reduces the computation time by more than 35%. Through physical constraint learning using an improved loss function related to the TF excitation efficiency, the axial resolution and excitation intensity of the proposed TF-DeepCGH with DPM rival that of the optimal GS with TF method but with a greatly increased computational efficiency.

Damage Monitoring of Composite Adhesive Joint Integrity Using Conductivity and Fiber Bragg Grating.

Adhesive joints possess a number of advantages over traditional joining methods and are widely used in composite structures. Conventional non-destructive examination techniques do not readily reveal joint degradation before the formation of explicit defects. Embedded fiber Bragg grating (FBG) sensors and the resistance of carbon nanotube (CNT)-doped conductive joints have been proposed to monitor the structural integrity of adhesive joints. Both techniques will be employed and compared in the current work to monitor damage development in adhesive joints under tensile and cyclic fatigue loading. Most of the previous works took measurements under an applied load, which by itself will affect the monitoring signals without the presence of any damage. Moreover, most FBG works primarily relied on the peak shifting phenomenon for sensing. Degradation of adhesive and inter-facial defects will lead to non-uniform strain that may chirp the FBG spectrum, causing complications in the peak shifting measurement. In view of the above shortfalls, measurements are made at some low and fixed loads to preclude any unwanted effect due to the applied load. The whole FBG spectrum, instead of a single peak, will be used, and a quantitative parameter to describe spectrum changes is proposed for monitoring purposes. The extent of damage is revealed by a fluorescent penetrant and correlated with the monitoring signals. With these refined techniques, we hope to shed some light on the relative merits and limitations of the two techniques.

Surface modification of zirconia ceramics through cold plasma treatment and the graft polymerization of biomolecules.

Background/purpose: Although zirconia ceramics were highly versatile as dental implants, their long-term presence in the human body may slow down healing and impede cell growth in the past. To enhance the cytocompatibility of zirconia ceramics, surface activation modification was used to immobilize biopolymers such that a biomimetic environment was created. Materials and methods: Hexamethyldisilazane thin films were deposited onto the surface of inorganic zirconia through cold plasma treatment under various power and deposition time settings to form an organosilane interface layer. Next, oxygen plasma treatment was performed to activate the free radicals on the surface. Subsequently, ultraviolet light was employed to graft and polymerize acrylic acid for generating carboxyl groups on the surface. This was followed by a condensation reaction with biopolymers (chitosan, chitosan/poly-γ-glutamic acid, and gelatin). Results: Under a 20-min deposition time at 40 W and 150 mTorr, the thin films had a maximum graft density of 2.1 mg/cm2. MG-63 cells (human osteosarcoma cells) were employed to evaluate cell compatibility. Chitosan and chitosan/poly-γ-glutamic acid promoted the compatibility of MG-63 cells (a human osteosarcoma cell line) with zirconia ceramics, whereas gelatin reduced this compatibility. Conclusion: The findings confirm that cold plasma treatment and graft polymerization can promote the immobilization of biomolecules and improve the biocompatibility of zirconia ceramics. This approach can be applied to the modification of zirconia ceramic implants.

Programmed Death-1 Deficiency Aggravates Motor Dysfunction in MPTP Model of Parkinson's Disease by Inducing Microglial Activation and Neuroinflammation in Mice.

Abundant reactive gliosis and neuroinflammation are typical pathogenetic hallmarks of brains in Parkinson's disease (PD) patients, but regulation mechanisms are poorly understood. We are interested in role of programmed death-1 (PD-1) in glial reaction, neuroinflammation and neuronal injury in PD pathogenesis. Using PD mouse model and PD-1 knockout (KO) mice, we designed wild-type-control (WT-CON), WT-1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (WT-MPTP), PD-1-KO-control (KO-CON) and PD-1-KO-MPTP (KO-MPTP), and observed motor dysfunction of animal, morphological distribution of PD-1-positive cells, dopaminergic neuronal injury, glial activation and generation of inflammatory cytokines in midbrains by motor behavior detection, immunohistochemistry and western blot. WT-MPTP mouse model exhibited decrease of PD-1/Iba1-positive microglial cells in the substantia nigra compared with WT-CON mice. By comparison of four groups, PD-1 deficiency showed exacerbation in motor dysfunction of animals, decreased expression of TH protein and TH-positive neuronal protrusions. PD-1 deficiency enhanced microglial activation, production of proinflammatory cytokines like inducible nitric oxide synthase, tumor necrosis factor-α, interleukin-1ß and interleukin-6, and expression and phosphorylation of AKT and ERK1/2 in the substantia nigra of MPTP model. We concluded that PD-1 deficiency could aggravate motor dysfunction of MPTP mouse model by inducing microglial activation and neuroinflammation in midbrains, suggesting that PD-1 signaling abnormality might be possibly involved in PD pathogenesis.

Palladium-Catalyzed Regiospecific Decarboxylative Allylation of (Cyclohexadienylidene)malononitriles: Access to α-Allyl-α-aryl Malononitriles.

A palladium-catalyzed regiospecific decarboxylative ε-allylation of (cyclohexadienylidene)malononitriles is presented for the synthesis of functionalized α-allyl-α-aryl malononitriles. This reaction proceeds via a resonance-stabilized α-aryl malononitrile anion, resulting in a wide range of α-allyl-α-aryl malononitriles in high yields with excellent linear product selectivity. We have also shown that the resulting products can be transformed into valuable synthetic intermediates by decyanation and Mizoroki-Heck arylation. In addition, an enantioselective decarboxylative allylation reaction is also presented.

Bilateral Cavernous Sinus Dural Arteriovenous Fistulae : The Strategies for Endovascular Treatment.

PURPOSE: Most cavernous sinus dural arteriovenous fistulas (CSDAVF) are unilateral; however, simultaneous bilateral CSDAVFs occasionally may be found. This article reports on 141 patients and compares the angioarchitecture and outcomes of embolization of bilateral CSDAVFs with those of unilateral CSDAVFs, with reference to limited demographics (sex and age) of the patients. METHOD: From January 2010 to February 2018 a total of 141 consecutive patients with CSDAVFs were referred for transvenous embolization. Bilateral CSDAVFs were found in 20 patients (14.2%, with a mean age of 62.2 years). The angioarchitecture of the 141 patients with CSDAVFs were evaluated by conventional cerebral angiography. We compared the angioarchitecture and treatment outcomes of 20 bilateral and 121 unilateral CSDAVFs, and in relation to the patients' sex and age. RESULTS: Female patients significantly dominated the bilateral CSDAVFs (90%, p = 0.043). Bilateral eye symptoms were significantly more common in bilateral CSDAVFs (p = 0.011), with dominant orbital and cavernous symptoms, and showed statistical significance (p = 0.049 and 0.011, respectively). Occlusion of one CSDAVF may significantly decrease the fistula flow of the other untreated side (n = 13, 65%), leading to less coil utilization for embolization in bilateral CSDAVFs (p < 0.001). There was no statistical significance in the occurrence of occlusion of the inferior petrous sinus(s), in pial vein reflux, and treatment outcomes in the unilateral and bilateral CSDAVFs. CONCLUSION: Bilateral CSDAVFs were more dominant in female patients and frequently presented with orbital and cavernous symptoms. Fewer coils were used per lesion in the bilateral CSDAVFs. There was no statistical significance in bilateral and unilateral CSDAVFs in terms of impact of venous drainage, pial vein reflux and treatment outcomes.

Reactive Astrocytes Display Pro-inflammatory Adaptability with Modulation of Notch-PI3K-AKT Signaling Pathway Under Inflammatory Stimulation.

Astrocytes are major glial cells critical in assisting the function of the central nervous system (CNS), but the functional changes and regulation mechanism of reactive astrocytes are still poorly understood in CNS diseases. In this study, mouse primary astrocytes were cultured, and inflammatory insult was performed to observe functional changes in astrocytes and the involvement of Notch-PI3K-AKT signaling activation through immunofluorescence, PCR, Western blot, CCK-8, and inhibition experiments. Notch downstream signal Hes-1 was clearly observed in the astrocytes, and Notch signal inhibitor GSI dose-dependently decreased the cleaved Notch-l level without an influence on cell viability. Inflammatory insult of lipopolysaccharide plus interferon-γ (LPS+IFNγ) induced an increase in pro-inflammatory cytokines, that is, iNOS, IL-1ß, IL-6, and TNF, at the protein and mRNA levels in activated astrocytes, which was reduced or blocked by GSI treatment. The cell viability of the astrocytes did not show significant differences among different groups. While an increase in MyD88, NF-кB, and phosphor-NF-кB was confirmed, upregulation of PI3K, AKT, and phosphor-AKT was observed in the activated astrocytes with LPS+IFNγ insult and was reduced by GSI treatment. Inhibitor experiments showed that inhibition of Notch-PI3K-AKT signaling activation reduced the pro-inflammatory cytokine production triggered by LPS+IFNγ inflammatory insult. This study showed that the reactive astrocytes displayed pro-inflammatory adaptability through Notch-PI3K-AKT signaling activation in response to inflammatory stimulation, suggesting that the Notch-PI3K-AKT pathway in reactive astrocytes may serve as a promising target against CNS inflammatory disorders.

Reactive astrocytes increase expression of proNGF in the mouse model of contused spinal cord injury.

Astrocytes are major glial cells critically in maintaining stability of the central nervous system and functional activation of astrocytes occurs rapidly in various diseased or traumatic events. We are interested in functional changes of astrocytes during the spinal cord injury, and studied expression of nerve growth factor (NGF) in activated astrocytes by mouse model of contused spinal cord injury and cell culture experiment. It revealed that the spinal cord injury resulted in apparent activation of astrocytes and microglial cells and decreased BMS scores. A larger number of astrocytes showed immunoreactivity to proNGF in the injured spinal cord areas, and proNGF expression increased and remained high level at 7 to 14dpi, which was coincided with upregulation of glial fibrillary acidic protein. The proNGF was clearly localized in both exosome-like vesicles and cytoplasm of astrocytes in culture. Electron microscopy confirmed exosome-like vesicles with proNGF-immunoreactivity in diameter sizes of 50-100 nm. Finally, cell culture with lipopolysaccharide (LPS) experiment indicated increasing expression and release of proNGF in the astrocytes with LPS exposure. This study demonstrated that reactive astrocytes increased proNGF expression after spinal cord injury, also suggesting involvement of exosome-like proNGF transport or release in triggering neuronal apoptosis and aggravating progression of spinal cord injury.

Fluoroscopic angiography quantifies delay in cerebral circulation time and requires less radiation in carotid stenosis patients: A pilot study.

BACKGROUND: Quantitative digital subtraction angiography (DSA) facilitates in-room assessment of flow changes in various cerebrovascular diseases and improves patient safety. The purpose of this study was to compare the diagnostic accuracy of quantitative fluoroscopic angiography (FA) and DSA. METHODS: Twenty-two patients with >70% carotid stenosis according to NASCET criteria were prospectively included in the study. All patients received DSA and FA (ArtisZee, Siemens Healthcare, Forchheim, Germany) before and after carotid stenting in the same angiosuite. The regions of interest (ROIs) included the extracranial internal carotid artery (eICA), first segment of the middle cerebral artery (MCA1), and sigmoid sinus in the anterior-posterior view; cavernous portion of the ICA (cICA), parietal vein, and jugular vein in the lateral views. The time-to-peak (TTP) for all ROIs and cerebral circulation time (CCT) were measured from FA and DSA scans. TTP, CCT, and radiation doses from DSA were compared with those from FA. RESULTS: The mean age of the patients were 69 ± 9.5 years old. The average stenosis was 89.7% ± 7.8% before stenting and 31% ± 3.6% after stenting. No patient suffered from periprocedural stroke. The intermethod correlation for TTP for all ROIs except the eICA and cICA ranged from 0.46 to 0.65 before stenting and 0.57 to 0.73 after stenting, and that for CCT was 0.65 before stenting and 0.57 after stenting. The radiation doses were significantly lower for FA than for DSA regardless of views or periprocedural timing (p < 0.001). CONCLUSION: Stenosis facilitated the creation of a bolus by manual injection and therefore increased the accuracy of cerebral flow quantification in FA. Cerebral hemodynamic assessment by FA is quicker and associated with less radiation.

Evaluating cerebral hemodynamics using quantitative digital subtraction angiography and flat-detector computed tomography perfusion imaging: A comparative study in patients with carotid stenosis.

BACKGROUND: The efficacy of both quantitative digital subtraction angiography (QDSA) and flat-detector computed tomography perfusion (FD-CTP) is equivalent to that of magnetic resonance perfusion (MRP) in assessing perfusion deficits in carotid stenosis. This study evaluated the feasibility of using FD-CTP to monitor cerebral hemodynamics during carotid stenting. METHODS: Thirteen patients with extracranial carotid stenosis (>70%) were included. Both QDSA and two FD-CTP sessions were performed before and after carotid stenting. Cerebral circulation time (CCT) was defined as the difference between the time to peak (TTP) of the parietal vein and the cavernous internal carotid artery. For FD-CTP and MRP, regions of interest (ROIs) were placed in the middle cerebral artery territory at the basal ganglia level of both stenotic and contralateral hemispheres for measurement. The TTP ratio (rTTP) was defined as stenotic TTP divided by contralateral TTP; and ratio of cerebral blood volume (rCBV), ratio of mean transit time (rMTT), and ratio of cerebral blood flow (rCBF) were defined similarly. Both CCT and ratio perfusion parameters were compared during stenting. RESULTS: Before stenting, only rCBF (r = 0.73) and rTTP (r = 0.58) demonstrated correlations between FD-CTP and MRP; CCT correlated with only rMTT in MRP (r = 0.69). After stenting, only rCBF (r = 0.56) indicated a correlation between FD-CTP and MRP. Regarding cerebral flow after stenting, CCT (4.61 ± 1.6 s) was shortened, rMTT (1.12 ± 0.04) and rTTP (r = 1.05 ± 0.03) decreased, and rCBF (0.91 ± 0.16) increased significantly. CONCLUSION: FD-CTP provides a potentially more comprehensive hemodynamic assessment of parenchymal perfusion changes compared with QDSA during carotid stenting, but FC-CTP requires additional 18 min. FD-CTP confirmed that the normalization of cerebral hemodynamics began immediately and continued for 1-3 days.

ERK potentiates p38 in central sensitization induced by traumatic occlusion.

This study was to investigate the role of p38 activation via ERK1/2 phosphorylation in neurons and microglia of the spinal trigeminal subnucleus caudalis (Vc) in the promotion of orofacial hyperalgesia induced by unilateral anterior crossbite (UAC) traumatic occlusion in adult rats. U0126, a p-ERK1/2 inhibitor, was injected intracisternally before UAC implant. The effects of the U0126 injection were compared to those following the injection of SB203580, a p-p38 inhibitor. Mechanical hyperalgesia was evaluated via pressure pain threshold measurements. Brain stem tissues were processed for a Western blot analysis to evaluate the activation of ERK1/2 and p38. Double immunofluorescence was also performed to observe the expression of p-ERK1/2 and p-p38 in neurons (labeled by NeuN) and microglia (labeled by OX42). The data showed that UAC caused orofacial hyperalgia ipsilaterally on d1 to d7, peaking on d3 (P<0.05). An upregulation of p-ERK1/2 was observed in the ipsilateral Vc on d1 to d3, peaking on d1. An upregulation of p-p38 was also observed on d1 to d7, peaking on d3 (P<0.05). p-ERK1/2 primarily co-localized with NeuN and, to a lesser extent, with OX42, while p-p38 co-localized with both NeuN and OX42. Pretreatment with U0126 prevented the upregulation of both p-ERK1/2 and p-p38. Similarly to an intracisternal injection of SB203580, U0126 pretreatment attenuated the UAC-induced orofacial hyperalgesia. These data indicate that UAC caused orofacial hyperalgesia by inducing central sensitization via the activation of ERK1/2 and p38 in both neurons and microglia in the Vc, potentially impacting the effects of p-ERK1/2 during p38 activation.

Gas1 up-regulation is inducible and contributes to cell apoptosis in reactive astrocytes in the substantia nigra of LPS and MPTP models.

BACKGROUND: Reactive astrogliosis is a remarkable pathogenetic hallmark of the brains of Parkinson's disease (PD) patients, but its progressive fate and regulation mechanisms are poorly understood. In this study, growth arrest specific 1 (Gas1), a tumor growth suppressor oncogene, was identified as a novel modulator of the cell apoptosis of reactive astrocytes in primary culture and the injured substantia nigra. METHODS: Animal models and cell cultures were utilized in the present study. Lipopolysaccharide (LPS)- and 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP)-treated animal models were used to detect Gas1 expression in the brain via immunohistochemistry and western blot. Cell cultures were performed to analyze Gas1 functions in the viability and apoptosis of reactive astrocytes and SH-SY5Y cells by double labeling, CCK-8, LDH, TUNEL, flow cytometry, and siRNA knockdown methods. RESULTS: Gas1 expressions were significantly elevated in the majority of the reactive astrocytes of the brains with LPS or MPTP insults. In the injured substantia nigras, GFAP-positive astrocytes exhibited higher levels of cleaved caspase-3. In cell culture, the up-regulated Gas1 expression induced apoptosis of reactive astrocytes that were insulted by LPS in combination with interferon-γ and tumor necrosis factor-a. This effect was confirmed through siRNA knockdown of Gas1 gene expression. Finally and interestingly, the potential underlying signaling pathways were evidently related to an increase in the Bax/Bcl-2 ratio, the abundant generation of reactive oxygen species and the activation of cleaved caspase-3. CONCLUSIONS: This study demonstrated that the up-regulation of inducible Gas1 contributed to the apoptosis of reactive astrocytes in the injured nigra. Gas1 signaling may function as a novel regulator of astrogliosis and is thus a potential intervention target for inflammatory events in PD conditions.

[The "Yin/Yang" Functional Features of Neurotrophic Factors].

Neurotrophic factor is a kind of protein family that plays an important role in the nutrition, support and differentiation to central neurons as well as synaptic plasticity. Growing evidences have revealed that pro-forms of various neurotrophic factors, which are generated in process of protein synthesis and might exert opposite roles involving in inducement of neuronal apoptosis and implication in pathogenesis of neurodegenerative diseases. This paper reviews "Yin/Yang" features of neurotrophic factors in the anabolism, receptor regulation, functional aspects, and their related role in pathogenesis of neurodegenerative diseases. It is hopefully to provide new idea on understanding and investigation of the neurotrophic factors regarding on their functional, pathological and potential therapeutic significance.

Lead exposure induced microgliosis and astrogliosis in hippocampus of young mice potentially by triggering TLR4-MyD88-NFκB signaling cascades.

Proper proliferation and differentiation of neural stem cells or progenitors in hippocampus is critical to learn and memory functions, which might be disturbed by lead toxicity particularly in young individuals. While astroglial and microglial cells are known to play an important role in regulating neurogenesis of hippocampus, their abnormal response and influence on hippocampal neurogenesis remains unclear. In this study, therefore, glial response including microgliosis, astrogliogenesis and mediating involvement of TLR4-MyD88-NFκB signaling cascades were observed in hippocampus of young mice by animal model with lead (plumbum, Pb) exposure. It revealed that (1) significant microglial activation occurred in hippocampus soon following Pb exposure; (2) increased levels of TLR4, MyD88, NFκB expression were concomitantly detected; (3) BrdU-incorporated progenitor cells were observed in dentate gyrus with significantly-increased numbers at d28 in Pb insult group; (4) obvious astrogliogenesis was observed while these doublecortin-labeled differentiated neurons were not significantly changed in hippocampus; (5) administration of MyD88 inhibitory peptide attenuated or relieved above effects; (6) enhanced expression levels of IL-1ß, TNFα, p38MAPK and ERK1/2 were also detected in hippocampus, indicating potential implication of inflammatory response and MAPK signaling activation in lead-induced microgliosis and astrogliosis. Data of this study overall have indicated that lead exposure could trigger or induce abnormal microgliosis and astrogliogenesis in the hippocampus of young mice through triggering TLR4-MyD88-NFκB signaling cascades, which might possibly thereafter disturb hippocampal neurogenesis and functional plasticity.

The proform of glia cell line-derived neurotrophic factor: a potentially biologically active protein.

Growing evidences have revealed that the proforms of several neurotrophins including nerve growth factor (NGF), brain-derived neurotrophic factor (BDNF), and neurotrophin-3 (NT3), by binding to p75 neurotrophin receptor and sortilin, could induce neuronal apoptosis and are implicated in the pathogenesis of various neurodegenerative diseases. The glial cell line-derived neurotrophic factor (GDNF), one of the most potent useful neurotrophic factors for the treatment of Parkinson's disease (PD), is firstly synthesized as the proform (proGDNF) like other neurotrophin NGF, BDNF, and NT3. However, little is known about proGDNF expression and secretion under physiological as well as pathological states in vivo or in vitro. In this study, we investigated the expression profile and dynamic changes of proGDNF in brains of aging and PD animal models, with the interesting finding that proGDNF was a predominant form of GDNF with molecular weight of about 36 kDa by reducing and nonreducing immunoblots in adult brains and was unregulated in the aging, lipopolysaccharide (LPS), and 1-methyl-4-phenyl- 1,2,3,6-tetrahydropyridine (MPTP) insult. We further provided direct evidence that accompanied activation of primary astrocytes as well as C6 cell line induced by LPS stimulation, proGDNF was increasingly synthesized and released as the uncleaved form in cell culture. Taken together, our results strongly suggest that proGDNF may be a biologically active protein and has specific effects on the cells close to its secreting site, and a potentially important role of proGDNF signaling in the brains, in the glia-neuronal interaction or in the pathogenesis of PD, should merit further investigation.

Functional switch from pro-neurotrophins to mature neurotrophins.

Growing evidence has shown that the proforms of several neurotrophins, e.g., nerve growth factor (NGF), brain-derived neurotrophic factor (BDNF), neurotrophin3 (NT3) can be synthesized, secreted from neurons or glial cells and function actively in mammalian nervous system. By the intracellular and extracellular enzymatic cleavage processing, mature neurotrophins are generated and exert their functions in the developing, physiological and pathological activities. While mature neurotrophins exhibit neuroprotective roles via tyrosine kinase receptors (TrkA, TrkB and TrkC), the proforms of neurotrophins show totally-different biological effects that may induce apoptotic cell death of neurons by triggering p75NTR-sortilin signaling cascades. In addition, another key neurotrophic factor named glial-derived neurotrophic factor (GDNF) also appears to be a product generated from proGDNF, and its cleavage and potential biological function of proGDNF remains an unrevealed problem. Obviously, accumulating studies indicated that the exact or timely cleavage processing should be essential for the functional switch from proneurotrophins to mature neurotrophins, while dysfunction in the enzymatic cleavage, aberrant extracellular release, and abnormal subunit organization of binding receptors might be also crucially involved in neurodegeneration of the central neurons, pathogenesis, and even disease progression of various neurodegenerative diseases in human beings.

LPS-induced proNGF synthesis and release in the N9 and BV2 microglial cells: a new pathway underling microglial toxicity in neuroinflammation.

PURPOSE: While aberrant activation of microglial cells was evidently involved in neuroinflammation and neurotoxicity in the neurodegenerative diseases such as Alzheimer's and Parkinson's disease, objective of study was to address if activated microglias deliver their effect by releasing pro-neurotrophins. MATERIALS AND METHODS: By in vitro culture of N9 and BV2 cell lines and lipopolysaccharide (LPS) stimulation model, generation and release of proNGF, proBDNF and MMP-9 was studied in the activated microglial cells by immunocytochemistry, western blotting and bioassay methods. RESULTS: Activation of microglial cells was observed with obvious increasing iba1-immunoreactivity following LPS stimulation in cell culture. Synthesis and up-regulation of proNGF protein significantly occurred in N9 and BV2 cells 12h-48h after LPS exposure, whereas no significant changes of proBDNF and MMP9 were observed in these microglial cell lines with LPS insult. More interestingly, extracellular release or secretion of proNGF molecule was also detected in culture medium of N9 cells after LPS stimulation. Finally, bioassay using MTT, Hoechst/PI and TUNEL staining in SH-SY5Y cells further confirmed that proNGF treatment could result in apoptotic cell death but it did not significantly influence cell viability of SH-SY5Y cells. CONCLUSIONS: This in vitro study revealed LPS-stimulated proNGF synthesis and release in activated N9/BV2 microglial cell lines, also suggesting that proNGF may appeal a new pathway or possible mechanism underlying microglial toxicity in the neuroinflammation and a potential target for therapeutic manipulation of the neurodegenerative diseases.

Increased expression of cannabinoid receptor 1 in the nucleus accumbens core in a rat model with morphine withdrawal.

Relapse is a major clinical problem and remains a major challenge in the treatment of drug addiction. There is strong evidence that the endocannabinoid system of the nucleus accumben core (NAcc) is involved in drug-seeking behavior, as well as in the mechanisms that underlie relapse to drug use. To reveal the mechanism that underlies this finding, we examined the expression pattern of the cannabinoid receptor 1 (CB1-R) in the NAcc of SD rats that had been undergoing morphine withdrawal (MW) for 1 day, 3 days and 3 weeks (acute, latent and chronic phases, respectively). Morphine exposure induced conditioned place preference (CPP) in rats. Significant increase of CB1-R expression in NAcc was observed in animals in the 1 day, 3 days and 3 weeks morphine withdrawal compare to the control group. Immunofluorescence labeling showed axonal fibers or terminals by fluorescence microscope observation. Immunoelectron microscopy detection showed silver-gold particles located in the presynaptic membranes that mainly give rise to symmetrical synapses. Quantitative electron microscopy showed an increase in number of CB1-R-positive terminals in the morphine withdrawal groups and the number of immunogold particles was significantly increased at these inhibitory terminals. We also confirmed that infusions of the CB1-R antagonist rimonabant into the NAcc attenuated the CPP during morphine withdrawal. Our present data have thus indicated that increasing pattern of CB1-R expression in the NAcc during above morphine withdrawal phases, which might underlie the relapse associated drug seeking behavior after morphine withdrawal.