Biomedical subjects

Li Duan

Publications and source records attributed to Li Duan.

11 recordsLinked to original sources

PubMed2006

Blocking the glial function suppresses subcutaneous formalin-induced nociceptive behavior in the rat.

This study examined whether glial cells in the trigeminal nucleus caudalis (Sp5C) were necessary for orofacial nociception and nociceptive processing induced by subcutaneously (s.c.) injection of 5% formalin into left mystacial vibrissae. The immunohistochemical, immunoelectron microscopical methods and behavior assessment were used in this study. Two hours after administration of carbenoxolone (CBX, a gap junction blocker) or fluorocistrate (FCA, a glail metabolic inhibitor) into the cerebellomedullary cistern, the nociceptive behavior and scratching-cumulative time reduced significantly (P<0.01). FCA attenuated obviously the expression of Fos/NeuN-immunoreactive (-IR) neurons (mean+/-S.E.M.=29+/-2.5) and Fos/glial fibrillary acidic protein (GFAP)-IR astrocytes (7.2+/-2.2) in Sp5C. CBX decreased the number of Fos/NeuN-IR neurons (25+/-1.7), but did not affect Fos/GFAP-IR astrocytes (16.2+/-5.4), compared with vehicle-preadministered rats (Fos/NeuN-IR neurons 135+/-4.2, and Fos/GFAP-IR astrocytes 25.8+/-4). Immunoelectron microscopy established that Cx32/Cx43 heterotypic gap junctions (HGJs) were present on junction areas between astrocytes and neurons within Sp5C. The number of HGJs increased significantly following formalin s.c. injection. It suggests that the Sp5C astrocytes may play an active regulating role in orofacial nociception via Cx32/Cx43 HGJs between astrocytes and neurons of Sp5C.

Animals↗

PubMed2006

Overexpression of BLCAP induces S phase arrest and apoptosis independent of p53 and NF-kappaB in human tongue carcinoma : BLCAP overexpression induces S phase arrest and apoptosis.

Bladder cancer-associated protein gene (BLCAP) is a novel candidate tumor suppressor gene identified from the human bladder carcinoma. Our previous studies have shown that BLCAP overexpression could inhibit cell growth by inducing apoptosis in HeLa cells [Zuo Z, Zhao M, Liu J, Gao G, Wu X: Tumor Biol 27: 221-226, 2006]. Such evidence suggests the alterations in BLCAP may play an important role in tumorigenesis. To further study the biological function of the BLCAP gene, we constructed a recombinant retroviral vector encoding BLCAP cDNA. Overexpressed BLCAP, via stable infection of exogenous BLCAP, resulted in growth inhibition of the human tongue cancer cell line Tca8113 in vitro, accompanied by S phase cell cycle arrest and apoptosis. The growth inhibition was correlated with up-regulation of p21(WAF1/CIP1 )expression and down-regulation of Bcl-XL and Bcl-2 expressions. However, p53 expression and NF-kappaB activity remained unchanged post infection. Furthermore, no changes in p53 phosphorylation at Ser46 and nuclear localization, which are critical to p53 function, were observed in BLCAP-overexpressed cells. Taken together, BLCAP may play a role not only in regulating cell proliferation but also in coordinating apoptosis and cell cycle via a novel way independent of p53 and NF-kappaB.

Animals↗

PubMed2006

Distinguishing source memory and item memory: brain potentials at encoding and retrieval.

Vivid memory for an episode generally includes memory for a central object or event plus memory for background context or source information. To assess neural differences between source and item memory, we used event-related potentials (ERPs) to monitor relevant memory processes at both encoding and retrieval. Participants fluent in Chinese studied Chinese words superimposed on a square or circular background during the study phase, followed by a 1-min delay. Then, memory was tested for both the words (items) and the corresponding background (source), or, in other blocks, tested for the words alone. ERPs to study-phase words differed as a function of whether the word was later remembered. These Dm effects in the interval from 400 to 600 ms, however, did not differ according to whether or not source was remembered. In contrast, ERPs to test-phase words showed clear old/new effects that did differ across conditions. When both item and source were remembered accurately, old/new effects emerged earlier and were larger in amplitude than when source memory was either incorrect or not queried. These results demonstrate that encoding processes indexed by ERPs may have primarily reflected encoding of the visual and semantic properties of these words, stressing item memory over source memory. Retrieval processes indexed by ERPs, in contrast, likely reflected a combination of item retrieval, source retrieval, and related processing engaged when people were remembering words seen earlier.

Adolescent↗

PubMed2006

NF-kappaB signaling pathway is involved in growth inhibition, G2/M arrest and apoptosis induced by Trichostatin A in human tongue carcinoma cells.

The HDAC inhibitor Trichostatin A (TSA) exhibits antitumour activity in various tumour cells. However, little is known about the effect of TSA on growth of human tongue carcinoma cells. In this study, we observed that TSA concentration-dependently inhibited growth of human tongue carcinoma Tca8113 cells by inducing G2/M arrest, apoptosis, up-regulation of the pro-apoptotic protein Bax and down-regulation of the anti-apoptotic proteins Bcl-2 and Bcl-XL which are regulated by the transcription factor nuclear factor (NF)-kappaB. Coincident with this observation, TSA induced a concentration-dependent reduction of constitutive and tumour necrosis factor (TNF)-alpha-induced NF-kappaB activation in Tca8113 cells. This induction was correlated with decreased phosphorylation and increased expression of inhibitors of NF-kappaB (IkappaB)alpha induced by TSA. Overall, our results indicate inhibition of NF-kappaB activation contributes, at least partially, to the antitumour activity of TSA in human tongue carcinoma cells.

Apoptosis↗

PubMed2006

Human serum albumin supported lipid patterns for the targeted recognition of microspheres coated by membrane based on ss-DNA hybridization.

Human serum albumin (HSA) patterns have been successfully fabricated for the deposition of lipid bilayer, 1,2-dimyristoyl-sglycerophosphate (DMPA), by making use of the micro-contact printing (microCP) technique and liposome fusion. Confocal laser scanning microscopy (CLSM) results indicate that lipid bilayer has been assembled in HSA patterns with a good stability. Such well-defined lipid patterns formed on HSA surface create possibility to incorporate specific components like channels or receptors for specific recognition. In view of this, microspheres coated with lipid membranes were immobilized in HSA-supported lipid patterns via the hybridization of complementary ss-DNAs. This procedure enables to transfer solid materials to a soft surface through a specific recognition.

DNA, Single-Stranded↗

PubMed2006

The lumbar spinal cord glial cells actively modulate subcutaneous formalin induced hyperalgesia in the rat.

We investigated the response and relationship of glial cells and neurons in lumbar spinal cord to hyperalgesia induced by the unilateral subcutaneous formalin injection into the hindpaw of rats. It was demonstrated that Fos/NeuN immunoreactive (-IR) neurons, glial fibrillary acidic protein (GFAP)-IR astrocytes and OX42-IR microglia were distributed in dorsal horn of lumbar spinal cord, predominantly in the superficial layer. In the time-course studies, GFAP-IR astrocytes were firstly detected, OX42-IR microglia were sequentially observed, Fos/NeuN-IR neurons were found slightly late. Immunoelectron microscopy studies established that many heterotypic gap junctions (HGJs), which consisting of Cx43-IR astrocytic process on one side and Cx32-IR dendrite on the other side, were present in superficial layer of dorsal horn. Ninety-one HGJs were found in 100 areas of experimental rats and occupied 91%, while only 39% HGJs were found in control rats. In experimental rats pretreated with intrathecal (i.t.) application of the carbenoxolone (a gap junction blocker) or fluorocitrate (a glial metabolic inhibitor), the paw withdrawal thermal latency was prolonged than those application of the sterile saline (i.t.). It suggests that spinal cord glial cells may play an important role for modulation of hyperalgesia induced by noxious stimuli through HGJs which located between astrocytes and neurons.

Afferent Pathways↗

PubMed2006

Growth suppression induced by Notch1 activation involves Wnt-beta-catenin down-regulation in human tongue carcinoma cells.

BACKGROUND INFORMATION: Involvement of Notch1 signalling in several cancers is well known, but its role in human tongue squamous cell carcinoma, one of the most common carcinomas of the human oral cavity, remains poorly characterized. RESULTS: Our studies demonstrated that constitutively over-expressed active Notch1, via stable transfection of exogenous ICN (intracellular fragment of Notch), resulted in growth suppression of the human tongue cancer cell line Tca8113 in vitro and in vivo, accompanied by G(0)-G(1) cell cycle arrest and apoptosis. Moreover, down-regulation of beta-catenin protein expression was observed in Tca8113 cells stably expressing active Notch1. Activated Notch1 also led to dramatic increase in p21(WAF1/CIP1) and p53 expression with decreases in Skp2 (S-phase kinase-associated protein 2) and Bcl-2 (B-cell lymphocytic-leukaemia proto-oncogene 2) expression, which may participate in the induction of apoptosis and cell cycle arrest. CONCLUSIONS: Since the effects of the Notch1 pathway are cell-type specific and context-dependent in cell types where Notch1 has an anti-proliferative effect, down-regulation of Wnt/beta-catenin signalling may be one of the mechanisms which induces apoptosis and cell cycle arrest.

Animals↗

PubMed2006

[Induction of growth-associated protein-43 expression in airway afferent nerves of guinea pigs by allergic airway inflammation].

OBJECTIVE: To investigate the mechanisms underlying sensitization of airway sensory nerves induced by allergic airway inflammation. METHODS: Thirty-nine guinea pigs were divided randomly into three groups including group A (saline sensitized/challenged guinea pigs, n = 9), group B [ovalbumin (OVA) sensitized/saline challenged guinea pigs, n = 9], group C (OVA sensitized/challenged guinea pigs, n = 21). In group C, animals were subdivided into three groups with group C1 (treated by one OVA challenge, n = 6), group C2 (treated by 3 consecutive days OVA challenges, n = 6), group C3 (treated by 5 consecutive days OVA challenges, n = 9). The guinea pigs were sensitized by intraperitoneal injection of 0.5 ml saline (group A) or 0.5 ml 10% OVA (group B and C) on day 0 and challenged via the airway with saline (group A and B) or 1% OVA (group C) for 30 min on days 10, 11, 12, 13, and 14 by ultrasonic nebulization. The expression patterns of growth-associated protein-43 (GAP-43) in the airway nerve endings, the nodose and jugular ganglion neurons and the distribution relationships of GAP-43 with substance P (SP) and glial cell line-derived neurotrophic factor (GDNF) receptor components c-RET in the nodose and jugular ganglion neurons in guinea pig after allergic airway inflammation were studied using immunofluorescence double-labeling with laser confocal scanning microscopy, and Western blot. RESULTS: By morphological study, after 2 hours following 5 consecutive days OVA challenge, GAP-43 immunoreactivity (IR) positive nerve endings were observed in the large bronchi, distributing network-like in the submucosa, a few nerve endings extending between the epithelia in the guinea pig airways. A substantial amount of GAP-43 IR neurons were found in the nodose and jugular ganglion, and GAP-43 IR co-localized with SP were predominantly in the nodose ganglion neurons, but in the jugular ganglion neurons, GAP-43 IR and c-RET IR were co-localized predominantly. By Western blot, GAP-43 protein levels (A) were 0.38 +/- 0.04, 0.41 +/- 0.03, 0.49 +/- 0.05, 0.79 +/- 0.08, 0.76 +/- 0.04 in group A, B, C1, C2, C3 respectively, after 2 hours following 1, 3, 5 d challenged. GAP-43 protein levels were increased significantly in the nodose and jugular ganglion after 2 hours following the first OVA challenged (0.49 +/- 0.05, P < 0.05) when compared with that in group B, after 3 consecutive days OVA challenge treatment, GAP-43 protein expression levels (0.79 +/- 0.08) were increased more significantly (P < 0.01), compared with that in group B and reached the levels of GAP-43 of group C3 (0.76 +/- 0.04, P > 0.05). CONCLUSION: These data indicate that GAP-43 protein expression in airway afferent neurons including SP peptidergic neurons in the nodose ganglion and GDNF responsive neurons in the jugular ganglion in guinea pigs can be induced by allergic airway inflammation.

Allergens↗

PubMed2005

GFAP and Fos immunoreactivity in lumbo-sacral spinal cord and medulla oblongata after chronic colonic inflammation in rats.

AIM: To investigate the response of astrocytes and neurons in rat lumbo-sacral spinal cord and medulla oblongata induced by chronic colonic inflammation, and the relationship between them. METHODS: Thirty-three male Sprague-Dawley rats were randomly divided into two groups: experimental group (n = 17), colonic inflammation was induced by intra-luminal administration of trinitrobenzenesulfonic acid (TNBS); control group (n = 16), saline was administered intra-luminally. After 3, 7, 14, and 28 d of administration, the lumbo-sacral spinal cord and medulla oblongata were removed and processed for anti-glial fibrillary acidic protein (GFAP), Fos and GFAP/Fos immunohistochemistry. RESULTS: Activated astrocytes positive for GFAP were mainly distributed in the superficial laminae (laminae I-II) of dorsal horn, intermediolateral nucleus (laminae V), posterior commissural nucleus (laminae X) and anterolateral nucleus (laminae IX). Fos-IR (Fos-immunoreactive) neurons were mainly distributed in the deeper laminae of the spinal cord (laminae III-IV, V-VI). In the medulla oblongata, both GFAP-IR astrocytes and Fos-IR neurons were mainly distributed in the medullary visceral zone (MVZ). The density of GFAP in the spinal cord of experimental rats was significantly higher after 3, 7, and 14 d of TNBS administration compared with the controls (50.4+/-16.8, 29.2+/-6.5, 24.1+/-5.6, P<0.05). The density of GFAP in MVZ was significantly higher after 3 d of TNBS administration (34.3+/-2.5, P<0.05). After 28 d of TNBS administration, the density of GFAP in the spinal cord and MVZ decreased and became comparable to that of the controls (18.0+/-4.9, 14.6+/-6.4, P>0.05). CONCLUSION: Astrocytes in spinal cord and medulla oblongata can be activated by colonic inflammation. The activated astrocytes are closely related to Fos-IR neurons. With the recovery of colonic inflammation, the activity of astrocytes in the spinal cord and medulla oblongata is reduced.

Animals↗

PubMed2004

[Effects of fraction from Phyllanthus urinaria on thrombosis and coagulation system in animals].

OBJECTIVE: To investigate the effects of PUW (a fraction containing 60% corilagin from a Chinese herbal plant Phyllanthus urinaria) on thrombosis and coagulation system. METHODS: Myers's method was used to evaluate the protection of intravenously administered PUW against the male mouse sudden death caused by injection of 75 mg/kg arachidonic acid in the tail vein; Charlton's method was modified to observe antithrombotic effect of PUW in rat electrically stimulated carotid artery thrombosis model; and the model of venous thrombosis was produced to investigate the antithrombotic effect of PUW. Rosette assay was used to observe the effect of PUW on platelet-neutrophil adhesion. The effects of PUW were monitored on euglobulin lysis time (ELT), prothrombin time (PT), kaolin partial thromboplastin time (KPTT), and bleeding time (BT) in rats, according to the methods of Kowalski, HUANG Zheng-Liang, and GU Yue-Fang, et al, respectively. RESULTS: The results showed that PUW administered intravenously significantly decreased the mouse mortality, prolonged the occlusion time of rat carotid arteries, and reduced the wet and dry thrombus weight of the inferior vena cava, respectively. PUW markedly inhibited the binding of activated platelets to neutrophils, obtaining 39.7 mg/L of the medium inhibitory concentration. Intravenously administered PUW significantly shortened ELT, prolonged KPTT while had no influence on PT; PUW increased BT in rat tail tips but the BT caused by PUW was much shorter than that by aspirin or urokinase. CONCLUSION: It is suggested that PUW has the potential of antithrombosis due to its inhibition of platelet-neutrophil adhesion. PUW shows the tendency to bleeding, however, it could not cause serious bleeding side effect as compared with aspirin or urokinase.

Animals↗

PubMed2004

Ultrastructure of junction areas between neurons and astrocytes in rat supraoptic nuclei.

AIM: To determine the ultrastructure of junction areas between neurons and astrocytes of supraoptic nuclei in rats orally administered 30 g/L NaCl solution for 5 days. METHODS: The anti-connexin (CX) 43 and anti-CX32 double immunoelectromicroscopic labeled method, and anti-Fos or anti-glial fibrillary acidic protein (GFAP) immunohistochemistry were used to detect changes in the junctional area between neurons and astrocytes in supraoptic nuclei of 5 rats after 30 g/L NaCL solution was given for 5days. RESULTS: A heterotypic connexin32/connexin43 gap junction (HGJ) between neurons and astrocytes (AS) in rat supraoptic nuclei was observed, which was characterized by the thickening and dark staining of cytomembranes with a narrow cleft between them. The number of HGJs and Fos like immunoreactive (-LI) cells was significantly increased following hyperosmotic stimuli, that is, the rats were administered 30 g/L NaCl solution orally or 90 g/L NaCl solution intravenously. HGJs could be blocked with carbenoxolone (CBX), a gap junction blocker, and the number of Fos-LI neurons was significantly decreased compared with that in rats without CBX injection, while Fos-LI ASs were not affected. CONCLUSION: HGJ may be a rapid adaptive signal structure between neurons and ASs in response to stimulation.

Animals↗