Early-onset familial Alzheimer's disease (AD) is most commonly associated with the mutations in presenilin-1 (PS1). PS1 is the catalytic component of the ?-secretase complex, which cleaves amyloid precursor protein to produce amyloid-? (A?), the major cause of AD. Presenilin enhancer 2 (Pen2) is critical for activating ?-secretase and exporting PS1 from endoplasmic reticulum (ER). Among all the familial AD-linked PS1 mutations, mutations at the G206 amino acid are the most adjacent position to the Pen2 binding site. Here, we characterized the effect of a familial AD-linked PS1 G206D mutation on the PS1-Pen2 interaction and the accompanied alteration in ?-secretase-dependent and -independent functions. We found that the G206D mutation reduced PS1-Pen2 interaction, but did not abolish ?-secretase formation and PS1 endoproteolysis. For ?-secretase-dependent function, the G206D mutation increased A?42 production but not Notch cleavage. For ?-secretase-independent function, this mutation disrupted the ER calcium homeostasis but not lysosomal calcium homeostasis and autophagosome maturation. Impaired ER calcium homeostasis may due to the reduced mutant PS1 level in the ER. Although this mutation did not alter the cell survival under stress, both increased A?42 ratio and disturbed ER calcium regulation could be the mechanisms underlying the pathogenesis of the familial AD-linked PS1 G206D mutation.
WNT1 encodes a multifunctional signaling glycoprotein that is highly expressed in several malignant tumors. Patients with Wnt1-positive cancer are usually related to advanced metastasis. Here, we found that a stretch of G-rich sequences located at the WNT1 promoter region is capable of forming G-quadruplex structures. The addition of G-quadruplex structure stabilizers, BMVC and BMVC4, raises the melting temperature of the oligonucleotide formed by the WNT1 promoter G-rich sequences. Significantly, the expression of WNT1 was repressed by BMVC or BMVC4 in a G-quadruplex-dependent manner, suggesting that they can be used to modulate WNT1 expression. The role of G-quadruplex stabilizers on Wnt1-mediated cancer migration and invasion was further analyzed. The protein levels of ?-catenin, a mediator of the Wnt-mediated signaling pathway, and the downstream targets MMP7 and survivin were down-regulated upon BMVC or BMVC4 treatments. Moreover, the migration and invasion activities of cancer cells were inhibited by BMVC and BMVC4, and the inhibitory effects can be reversed by WNT1-overexpression. Thus the Wnt1 expression and its downstream signaling pathways can be regulated through the G-quadruplex sequences located at its promoter region. These findings provide a novel approach for future drug development to inhibit migration and invasion of cancer cells.
The dentate gyrus (DG) serves as a primary gate to control information transfer from the cortex to the hippocampus. Activation of incoming cortical inputs results in rapid synaptic excitation followed by slow GABA-mediated (GABAergic) synaptic inhibition onto DG granule cells (GCs). GABAergic inhibitory interneurons (INs) in the DG comprise fast-spiking (FS) and non-fast-spiking (non-FS) cells. Anatomical analyses of DG INs reveal that FS cells are soma-targeting INs, whereas non-FS cells are dendrite-targeting INs. These two IN classes are differentially recruited by excitatory inputs and in turn provide exquisite spatiotemporal control over GC activity. Yet, little is known how FS and non-FS cells transform their presynaptic dynamics into varying postsynaptic response amplitudes. Using paired recordings in rat hippocampal slices, we show that inhibition in the DG is dominated by somatic GABAergic inputs during periods of sparse presynaptic activity, whereas dendritic GABAergic inputs are rapidly shifted to powerful and sustained inhibition during periods of intense presynaptic activity. The variant dynamics of dendritic inhibition is dependent on presynaptic IN subtypes and their activity patterns and is attributed to Ca(2+)-dependent increases in the probability of release and the size of the readily releasable pool. Furthermore, the degree of dynamic GABA release can be reduced by blocking voltage-gated K(+) channels, which increases the efficacy of dendrite-targeting IN output synapses during sparse firing. Such rapid dynamic modulation of dendritic inhibition may act as a frequency-dependent filter to prevent overexcitation of GC dendrites and thus set the excitatory-inhibitory synaptic balance in the DG circuits.
Mirror-image pain is characterized by mechanical hypersensitivity on the uninjured mirror-image side. Recent reports favor central mechanisms, but whether peripheral mechanisms are involved remains unclear. We used unilateral spinal nerve ligation (SNL) to induce mirror-image pain in rats. On the mirror-image (contralateral) side, we found that satellite glia in the dorsal root ganglion (DRG) were activated, whereas macrophages/Schwann cells in the DRG and astrocytes/oligodendrocytes/microglia in the dorsal spinal cord were not. Subsequently, an increase in nerve growth factor (NGF) was detected in the contralateral DRG, and NGF immunoreactivity was concentrated in activated satellite glia. These phenomena were abolished if fluorocitrate (a glial inhibitor) was intrathecally injected before SNL. Electrophysiological recordings in cultured small DRG neurons showed that exogenous NGF enhanced nociceptor excitability. Intrathecal injection of NGF into naive rats induced long-lasting mechanical hypersensitivity, similar to SNL-evoked mirror-image pain. Anti-NGF effectively relieved SNL-evoked mirror-image pain. In the contralateral DRG, the SNL-evoked tumor necrosis factor alpha (TNF-?) increase, which started later than in the ipsilateral DRG and cerebrospinal fluid, occurred earlier than satellite glial activation and the NGF increase. Intrathecal injection of TNF-? into naive rats not only activated satellite glia to produce extra NGF in the DRG but also evoked mechanical hypersensitivity, which could be attenuated by anti-NGF injection. These results suggest that after SNL, satellite glia in the contralateral DRG are activated by TNF-? that diffuses from the injured side via cerebrospinal fluid, which then activates satellite glia to produce extra NGF to enhance nociceptor excitability, which induces mirror-image pain.
A number of diagnostic and management challenges exist for achieving complete regeneration of large through-and-through periapical lesions. An unfavorable endodontic outcome may occur as a result of uncontrolled infection or unpredictable bone healing. This article presents a case with a 15 × 15-mm through-and-through periapical lesion and persistent gingival swelling. Endodontic microsurgery and guided tissue regeneration were performed using a resorbable membrane and osseous substitute. A 2-year postoperative radiograph revealed complete resolution of the periapical radiolucency. Seven-year clinical and radiographic follow-up showed that the tooth was asymptomatic and a long-term successful outcome had been maintained.
Background: Areca quid chewing increases the prevalence of periodontal diseases. Areca nut extract (ANE) inhibits the phagocytic activity of human neutrophils. This in vitro study investigated the effects of ANE on complement and antibody-opsonized phagocytosis by neutrophils. Expression of complement receptors, Fc receptors and F-actin in ANE-treated neutrophils was also analyzed. Methods: The viability of ANE-treated neutrophils was determined using the propidium iodide staining method. The possible effects of ANE on the expression of complement receptors and Fc receptors were examined using an immunofluorescence staining method followed by flow cytometry and confocal laser scanning microscopy. The phagocytic activity of neutrophils against complement or immunoglobulin (IgG)-opsonized fluorescent beads was analyzed using flow cytometry. Expression of F-actin was determined using confocal laser scanning microscopy. Results: ANE significantly inhibited the production of complement receptor (CR1, CR3 and CR4) and Fc receptors (Fc?RII and Fc?RIII) in a concentration-dependent manner. Treatment of neutrophils with ANE significantly impaired their ability to phagocytose fluorescent beads. ANE also inhibited phagocytosis of fluorescent beads that were opsonized by complement or IgG. Moreover, expression of F-actin was inhibited after ANE treatment. Conclusions: ANE inhibited the complement and IgG-mediated neutrophil phagocytosis which may result from reduction of the expression of complement receptors, Fc receptors and F-actin formation after ANE treatment. The findings suggest that areca nut chewing may jeopardize the defensive functions of neutrophils and affect the periodontal health.
Background: Areca chewers have a higher prevalence of periodontitis than non-chewers. Cell adhesion and movement (migration) are important for the leukocyte recruitment to the inflammation sites. This study investigated the effects of areca nut extract (ANE) on the adhesion and migration abilities of human immune cells, peripheral blood mononuclear cells (PBMC). The combined effects of nicotine and lipopolysaccharides (LPS) were also analyzed. Methods: Purified PBMC obtained from healthy adults were treated with ANE, nicotine and/or LPS. Cell adhesion ability was examined using fibronectin-coated microslides, Lius stain and light microscopy. Cell migration ability was evaluated using the transwell system followed by staining and fluorescence microscopy. Statistical difference was analyzed using the Mann-Whitney test. Results: When compared to the media-treated control samples, PBMC treated with ANE for 4 hours showed a significant reduction of the adherent cells on the microslides. Interestingly, LPS treatment increased cell adhesion which could be reduced by simultaneous ANE plus nicotine treatment. The chemotactic migration of PBMC was reduced by ANE treatment for 1, 4 or 24 hours in a dose-dependent manner. LPS treatment increased PBMC migration which could be reduced by simultaneous treatment with ANE or with ANE plus nicotine. Conclusions: ANE reduced the adhesion and migration abilities of PBMC. ANE, with or without nicotine, also attenuated the migration of LPS-stimulated PBMC. The results implicated that the immune cell functions were impaired in areca chewers which might increase the host susceptibility to oral and periodontal infection.
Glutamatergic transmission onto oligodendrocyte precursor cells (OPCs) may regulate OPC proliferation, migration and differentiation. Dendritic integration of excitatory postsynaptic potentials (EPSPs) is critical for neuronal functions, and mechanisms regulating dendritic propagation and summation of EPSPs are well understood. However, little is known about EPSP attenuation and integration in OPCs. We developed realistic OPC models for synaptic integration, based on passive membrane responses of OPCs obtained by simultaneous dual whole-cell patch-pipette recordings. Compared with neurons, OPCs have a very low value of membrane resistivity, which is largely mediated by Ba(2+)- and bupivacaine-sensitive background K(+) conductances. The very low membrane resistivity not only leads to rapid EPSP attenuation along OPC processes but also sharpens EPSPs and narrows the temporal window for EPSP summation. Thus, background K(+) conductances regulate synaptic responses and integration in OPCs, thereby affecting activity-dependent neuronal control of OPC development and function.
Cervical cancer is an important health issue for women worldwide, and the endoplasmic reticulum stress pathway is important for determining the chemotherapeutic response to cancer. However, the role of glucose-regulated protein 94 (GRP94) in taxane therapy for cervical cancer remains unclear. In this study, we generated GRP94 knockdown (GRP94-KD) Hela cells using short hairpin RNAs and found that GRP94-KD cells were resistant to taxane treatment in an MTT assay. Scrambled control cells demonstrated higher levels of apoptosis when treated with taxanes in comparison to GRP94-KD cells, as determined by cell cycle profiling, 4,6-diamidino-2-phenylindole staining, and terminal deoxynucleotidyl transferase-mediated nick end labeling staining. Caspase 3 and caspase 7 activity was also higher in scrambled control cells treated with taxane in comparison to GRP94-KD cells. Moreover, we found that depletion of GRP94 altered the levels of the apoptosis-related proteins Bcl2 and Bad, leading to sensitivity to taxane. Exposure to taxane also induced the expression of Bad in scrambled cells but not in GRP94-KD cells. In addition, the expression of Bcl2 was increased dramatically in GRP94-KD cells, whereas only a small increase was observed in scrambled cells. Therefore, we conclude that silencing GRP94 may increase resistance to taxane treatment in cervical cancer cells by altering the activation of the apoptosis pathway. In addition, GRP94 may represent a key biomarker for determining the therapeutic efficacy of taxane treatment in cervical cancer patients.
Areca nut has been identified as a carcinogen. Inflammation reveals a strong link with tumourigenesis. The aim of this study was to investigate the effects of areca nut on the expression of the key pro-inflammatory mediators involved in malignancy, cyclooxygenase-2 (COX-2), prostaglandin E2 (PGE2), interleukin (IL)-1? and nuclear factor-?B (NF-?B), by human immune cells. The role of oxidative stress was also examined.
Background: Hyperglycemia is widely considered to be the causal link between diabetes mellitus (DM) and diabetic complications. The purpose of this study is to determine the effects of high glucose in the presence of lipopolysaccharide (LPS) purified from the periodontal pathogen Porphyromonas gingivalis on human macrophages. Methods: Macrophages (U937) were treated with various concentrations of P. gingivalis-LPS under normal (5.5 mM) or high (25 mM) glucose conditions. Mitochondrial dehydrogenase activity was determined using the 3-[4,5-dimethylthiazol-2-yl]-2,5 diphenyltetrazolium bromide assay. The levels of inflammatory mediators secreted were determined using the enzyme-linked immunosorbent assay and the competitive enzyme immunoassay. The intracellular calcium chelator was used to examine whether the intracellular calcium was involved. Statistical differences were assessed using a one-way analysis of variance and Tukey multiple-comparison intervals with ? = 0.05. Results: High glucose condition enhanced the mitochondrial dehydrogenase activity in macrophages. P. gingivalis-LPS induced the secretion of interleukin (IL)-6, tumor necrosis factor (TNF)-?, and prostaglandin E2 (PGE2) in a dose-dependent manner both in normal and high glucose conditions. The stimulatory effects by P. gingivalis-LPS were more evident when cells were cultured under high glucose conditions. Changes of intracellular calcium concentration were involved not only in high glucose-induced mitochondrial dehydrogenase activity but also in P. gingivalis-LPS-induced production of IL-6, TNF-?, or PGE2, especially under the high glucose conditions. Conclusions: High glucose appeared to enhance the inflammatory response induced by the periodontal pathogen. The information generated may help to delineate the possible mechanisms by which hyperglycemia compromises the periodontal health of patients with DM.
Acid-sensing ion channel-1a (ASIC1a) is localized in brain regions with high synaptic density and is thought to contribute to synaptic plasticity, learning, and memory. A prominent hypothesis is that activation of postsynaptic ASICs promotes depolarization, thereby augmenting N-methyl-d-aspartate receptor function and contributing to the induction of long-term potentiation (LTP). However, evidence for activation of postsynaptic ASICs during neurotransmission has not been established. Here, we re-examined the role of ASIC1a in LTP in the hippocampus using pharmacological and genetic approaches. Our results showed that a tarantula peptide psalmotoxin, which profoundly blocked ASIC currents in the hippocampal neurons, had no effect on LTP. Similarly, normal LTP was robustly generated in ASIC1a-null mice. A further behavioral analysis showed that mice lacking ASIC1a had normal performance in hippocampus-dependent spatial memory. In summary, our results indicate that ASIC1a is not required for hippocampal LTP and spatial memory. We therefore propose that the role of ASIC1a in LTP and spatial learning should be reassessed.
The neuroprotective effect of baicalein is generally attributed to inhibition of 12/15-lipoxygenase (12/15-LOX) and suppression of oxidative stress, but recent studies showed that baicalein also activates hypoxia-inducible factor-? (HIF1?) through inhibition of prolyl hydrolase 2 (PHD2) and activation of the phosphatidylinositide-3 kinase (PI3K)/Akt signaling pathway. Yet, the significance and regulation of prosurvival cytokines erythropoietin (Epo) and vascular endothelial growth factor (VEGF), two transcriptional targets of HIF1?, in baicalein-mediated neuroprotection in neurons and astrocytes remains unknown. Here we investigated the causal relationship between the PI3K/Akt signaling pathway and Epo/VEGF expression in baicalein-mediated neuroprotection in primary rat cortical neurons and astrocytes. Our results show that baicalein induced Epo and VEGF expression in a HIF1?- and PI3K/Akt-dependent manner in neurons. Baicalein also protected neurons against excitotoxicity in a PI3K- and Epo/VEGF-dependent manner without affecting neuronal excitability. In contrast, at least a 10-fold higher concentration of baicalein was needed to induce Epo/VEGF production and PI3K/Akt activity in astrocytes for protection of neurons. Moreover, only baicalein-induced astrocytic VEGF, but not Epo expression requires HIF1?, while PI3K/Akt signaling had little role in baicalein-induced astrocytic Epo/VEGF expression. These results suggest distinct mechanisms of baicalein-mediated Epo/VEGF production in neurons and astrocytes for neuroprotection, and provide new insights into the mechanisms and potential of baicalein in treating brain injury in vivo.
In this study, we intended to dissect the mechanism of 4-(Methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK)-enhanced migration of gastric cancer. Smoking has been defined as a risk factor for gastric cancer. Tobacco-specific carcinogen, NNK, was reported to enhance cancer progression in gastric cancer. Currently, metastasis is the major issue for clinical cancer therapy, but the influence of NNK on the migration of gastric cancer remains to be determined.
The objective was to study the mechanism of nicotine-enhanced migration of gastric cancer cells. Long-term cigarette smoking increases the risk of gastric cancer mortality. Tobacco-specific mitogen, nicotine, was reported to correlate with cancer progression on gastric cancer. Since metastasis is the major cause of cancer death, the influence of nicotine on the migration of gastric cancer cells remains to be determined.
Diabetic foot ulcers (DFUs) superimposed by infection and ischaemia may result in amputation without prompt and adequate management. We investigated whether the diabetic foot ulcer treatment programme (DFUTP) involving immediate debridement within 12 h, flap coverage and/or revascularisation improved the outcome of patients with infected DFUs.
MicroRNAs (miRNA) mediate distinct gene regulatory pathways triggered by epidermal growth factor receptor (EGFR) activation, which occurs commonly in lung cancers with poor prognosis. In this study, we report the discovery and mechanistic characterization of the miRNA miR-7 as an oncogenic "oncomiR" and its role as a key mediator of EGFR signaling in lung cancer cells. EGFR activation or ectopic expression of Ras as well as c-Myc stimulated miR-7 expression in an extracellular signal-regulated kinase (ERK)-dependent manner, suggesting that EGFR induces miR-7 expression through a Ras/ERK/Myc pathway. In support of this likelihood, c-Myc bound to the miR-7 promoter and enhanced its activity. Ectopic miR-7 promoted cell growth and tumor formation in lung cancer cells, significantly increasing the mortality of nude mice hosts, which were orthotopically implanted with lung cancers. Quantitative proteomic analysis revealed that miR-7 decreased levels of the Ets2 transcriptional repression factor ERF, the coding sequence of which was found to contain a miR-7 complementary sequence. Indeed, ectopic miR-7 inhibited production of ERF messages with a wild-type but not a silently mutated coding sequence, and ectopic miR-7 rescued growth arrest produced by wild-type but not mutated ERF. Together, these results identified that ERF is a direct target of miR-7 in lung cancer. Our findings suggest that miR-7 may act as an important modulator of EGFR-mediated oncogenesis, with potential applications as a novel prognostic biomarker and therapeutic target in lung cancer.
A highly regioselective one-pot transformation of 2-azido-2-deoxy-1,3,4,6-tetra-O-trimethylsilyl-d-glucopyranose via sequential additions of various reagents was systematically studied, yielding the fully protected derivatives and the 1-, 3-, 4-, as well as 6-alcohols, respectively.
Astrocytes function as spatial K(+) buffers by expressing a rich repertoire of K(+) channels. Earlier studies suggest that acid-sensitive tandem-pore K(+) channels, mainly TWIK-related acid-sensitive K(+) (TASK) channels, mediate part of the passive astroglial membrane conductance. Here, using a combination of electrophysiology and pharmacology, we investigated the presence of TASK-like conductance in hippocampal astrocytes of rat brain slices. Extracellular pH shifts to below 7.4 (or above 7.4) induced a prominent inward (or outward) current in astrocytes in the presence of tetrodotoxin, a Na(+) channel blocker, and 4,4-diisothiocyanatostilbene-2,2-disulfonate, a co-transporter blocker. The pH-sensitive current was insensitive to quinine, a potent blocker of tandem-pore K(+) channels including TWIK-1 and TREK-1 channels. Voltage-clamp analysis revealed that the pH-sensitive current exhibited weak outward rectification with a reversal potential of -112 mV, close to the Nernst equilibrium potential for K(+) . Furthermore, the current-voltage relationship was well fitted with the Goldman-Hodgkin-Katz current equation for the classical open-rectifier leak K(+) channel. The pH-sensitive K(+) current was potentiated by TASK channel modulators such as the volatile anesthetic isoflurane but depressed by the local anesthetic bupivacaine. However, unlike TASK channels, the pH-sensitive current was insensitive to Ba(2+) and quinine. Thus, the molecular identity of the pH-sensitive leak K(+) channel is unlikely to be attributable to TASK channels. Taken together, our results suggest a novel yet unknown leak K(+) channel underlying the pH- and anesthetic-sensitive background conductance in hippocampal astrocytes.
NG2 cells, a fourth type of glial cell in the mammalian CNS, undergo reactive changes in response to a wide variety of brain insults. Recent studies have demonstrated that neuronally expressed acid-sensing ion channels (ASICs) are implicated in various neurological disorders including brain ischemia and seizures. Acidosis is a common feature of acute neurological conditions. It is postulated that a drop in pH may be the link between the pathological process and activation of NG2 cells. Such postulate immediately prompts the following questions: Do NG2 cells express ASICs? If so, what are their functional properties and subunit composition? Here, using a combination of electrophysiology, Ca2+ imaging and immunocytochemistry, we present evidence to demonstrate that NG2 cells of the rat hippocampus express high density of Ca2+-permeable ASIC1a channels compared with several types of hippocampal neurons. First, nucleated patch recordings from NG2 cells revealed high density of proton-activated currents. The magnitude of proton-activated current was pH dependent, with a pH for half-maximal activation of 6.3. Second, the current-voltage relationship showed a reversal close to the equilibrium potential for Na+. Third, psalmotoxin 1, a blocker specific for the ASIC1a channel, largely inhibited proton-activated currents. Fourth, Ca2+ imaging showed that activation of proton-activated channels led to an increase of [Ca2+]i. Finally, immunocytochemistry showed co-localization of ASIC1a and NG2 proteins in the hippocampus. Thus the acid chemosensor, the ASIC1a channel, may serve for inducing membrane depolarization and Ca2+ influx, thereby playing a crucial role in the NG2 cell response to injury following ischemia.
Deinstitutionalization and the implementation of community psychiatry rehabilitation models define the future of psychiatric medical care in Taiwan. As such, managing and caring for psychiatric patients at the community level are increasingly important public health issues for county and city governments. A local public health authority in Taichung County established a collaborative relationship with a university-level nursing department during 2007 - 2008 in order to provide more effective continuous community care for psychiatric patients. This cooperative arrangement provided continuous community care for psychiatric patients in the County by implementing aftercare for psychiatric patients that was delivered through community-level public health centers, which conducted patient visits, developed discharge notifications for severe psychiatric patients in mental health institutions, and strengthened connections among related resources. To establish continuous community care for psychiatric patients, it is necessary to enhance training and support for health recipients as well as nursing staff in public health centers through measures that include: implementing discharge preparations and notifications in mental health institutions, improving the quality of community-based psychiatric patient visits, and connecting and integrating relevant resources effectively.
Acid-sensing ion channels (ASICs), a member of the degenerin/epithelial Na+ channel superfamily, are widely expressed in the mammalian CNS. Accumulating evidence suggests that ASIC current density is higher in GABAergic interneurons than that in glutamatergic pyramidal neurons (PNs) in the hippocampus. Such differential expression of ASICs in cortical networks is thought to be a key element for seizure termination. However, GABAergic interneurons are highly diverse; it is unclear whether the functional expression of ASICs differs in distinct GABAergic interneuron subtypes. Moreover, the subunit composition of ASICs in individual GABAergic interneurons remains unknown. By combining patch-clamp recording and single-cell reverse transcription (RT)-PCR analysis, we correlated ASIC currents with their gene expression in acute rat hippocampal slices. The results yielded several surprising findings. First, ASIC current density of oriens lacunosum-moleculare (O-LM) cells in the CA1 region, a classical type of dendrite-targeting interneuron, is 6 times greater than that of fast-spiking basket cells (BCs) in the dentate gyrus, a major class of soma-targeting interneuron. Second, the recovery of ASICs from desensitization is slowest in BCs, intermediate in PNs, and fastest in O-LM cells. Third, the tarantula venom psalmotoxin 1, the specific blocker for ASIC1a homomers, inhibits ASIC currents in BCs but not in O-LM cells. Finally, single-cell RT-PCR analysis reveals coexpression of ASIC1a and ASIC2 subunit transcripts in O-LM cells, whereas only ASIC1a subunit transcript is detected in most BCs. Thus, differential expression of ASICs in inhibitory microcircuits likely contributes to the distinct roles of GABAergic interneurons in normal physiology and pathophysiology.
Pituitary tumor transforming gene (PTTG1, securin) is involved in cell-cycle control through inhibition of sister-chromatid separation. Elevated levels of PTTG1 were found to be associated with many different tumor types that might be involved in late stage tumor progression. However, the role of PTTG1 in early stage of tumorigenesis is unclear. Here we utilized the adenovirus expression system to deliver PTTG1 into normal human fibroblasts to evaluate the role of PTTG1 in tumorigenesis. Expressing PTTG1 in normal human fibroblasts inhibited cell proliferation. Several senescence-associated (SA) phenotypes including increased SA-beta-galactosidase activities, decreased bromodeoxyuridine incorporation, and increased SA-heterochromatin foci formation were also observed in PTTG1-expressing cells, indicating that PTTG1 overexpression induced a senescent phenotype in normal cells. Significantly, the PTTG1-induced senescence is p53-dependent and telomerase-independent, which is distinctively different from that of replicative senescence. The mechanism of PTTG1-induced senescence was also analyzed. Consistent with its role in regulating sister-chromatid separation, overexpression of PTTG1 inhibited the activation of separase. Consequently, the numbers of cells with abnormal nuclei morphologies and chromosome separations were increased, which resulted in activation of the DNA damage response. Thus, we concluded that PTTG1 overexpression in normal human fibroblasts caused chromosome instability, which subsequently induced p53-dependent senescence through activation of DNA-damage response pathway.
Implant restoration in the anterior maxilla is a true challenge for clinicians. Facial tissue recession around the implant prosthesis is one of most difficult situations to correct. This report details the treatment of a female patient who presented with a root fracture of the maxillary left central incisor and crossbite of the left canines. The treatment protocol included implant placement and subsequent orthodontic treatment to correct the crossbite, with the implant used as adjunctive anchorage. However, labial tissue recession around the implant restoration occurred following orthodontic therapy. A resubmerged implant technique with connective tissue grafting for implant coverage was employed. The implant was uncovered again 2 months after the resubmergence treatment and the definitive prosthesis was delivered later. The resulting esthetic defect was restored and a 3-year postgrafting follow-up examination revealed that there was no further marginal tissue recession of the implant restoration. A harmonious soft tissue margin was achieved in the anterior esthetic region.
Safrole, a component of Piper betle inflorescence, inhibits bactericidal activity and the release of superoxide anion (O(2)(-)) by polymorphonuclear leukocytes (PMNs). This in vitro study further investigated the effects of safrole on phagocytic activity, the intracellular production of reactive oxygen species (ROS), and the activity of the lysosomal enzyme myeloperoxidase (MPO), which is released by human PMNs.
A modified technique for anterior cruciate ligament (ACL) reconstruction without graft injury by femoral interference screw insertion directly through the tibial tunnel is reported. This study evaluated femur bioabsorbable interference screw divergence and obliquity of the graft and tunnel positions as measured by multiplanar reconstruction computed tomography (MPR-CT) after endoscopic ACL reconstruction.
Accurate identification of patients at high risk of death as a result of major chest trauma is essential within a trauma system. We used 3-year population-based data in Taiwan to evaluate risk factors associated with 24-hour mortality among adults with obvious rib fractures and needing hospitalization after traffic accidents.
Impairment of learning and memory is a significant pathological feature of many neurodegenerative diseases including FTLD-TDP. Appropriate regulation and fine tuning of spinogenesis of the dendrites, which is an integral part of the learning/memory program of the mammalian brain, are essential for the normal function of the hippocampal neurons. TDP-43 is a nucleic acid-binding protein implicated in multi-cellular functions and in the pathogenesis of a range of neurodegenerative diseases including FTLD-TDP and ALS. We have combined the use of single-cell dye injection, shRNA knockdown, plasmid rescue, immunofluorescence staining, Western blot analysis and patch clamp electrophysiological measurement of primary mouse hippocampal neurons in culture to study the functional role of TDP-43 in mammalian spinogenesis. We found that depletion of TDP-43 leads to an increase in the number of protrusions/spines as well as the percentage of matured spines among the protrusions. Significantly, the knockdown of TDP-43 also increases the level of Rac1 and its activated form GTP-Rac1, a known positive regulator of spinogenesis. Clustering of the AMPA receptors on the dendritic surface and neuronal firing are also induced by depletion of TDP-43. Furthermore, use of an inhibitor of Rac1 activation negatively regulated spinogenesis of control hippocampal neurons as well as TDP-43-depleted hippocampal neurons. Mechanistically, RT-PCR assay and cycloheximide chase experiments have indicated that increases in Rac1 protein upon TDP-43 depletion is regulated at the translational level. These data together establish that TDP-43 is an upstream regulator of spinogenesis in part through its action on the Rac1 ? GTP-Rac1 ? AMPAR pathway. This study provides the first evidence connecting TDP-43 with the GTP-Rac1 ? AMPAR regulatory pathway of spinogenesis. It establishes that mis-metabolism of TDP-43, as occurs in neurodegenerative diseases with TDP-43 proteinopathies, e.g., FTLD-TDP, would alter its homeostatic cellular concentration, thus leading to impairment of hippocampal plasticity.
GABAergic signaling in hippocampal pyramidal neurons undergoes a switch from depolarizing to hyperpolarizing during early neuronal development. Whether such a transformation of GABAergic action occurs in dentate granule cells (DGCs), located at the first stage of the hippocampal trisynaptic circuit, is unclear. Here, we use noninvasive extracellular recording to monitor the effect of synaptically released GABA on the DGC population. We find that GABAergic responses in adolescent and adult rat DGCs are still depolarizing from rest. Using a morphologically realistic DGC model, we show that GABAergic action, depending on its precise timing and location, can have either an excitatory or inhibitory role in signal processing in the dentate gyrus.
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