Biomedical subjects

Xiao Han

Publications and source records attributed to Xiao Han.

31 records · Page 2Linked to original sources

PubMed2005

Potential role of NO in modulation of COX-2 expression and PGE2 production in pancreatic beta-cells.

Cytokines have been implicated in pancreatic beta-cell destruction leading to type 1 diabetes. Exposure to interleukin-1beta (IL-1beta) of pancreatic beta-cells induces expression of inducible nitric oxide synthase (iNOS) and cyclooxygenase-2 (COX-2). Subsequent formation of nitric oxide (NO) and prostaglandin E2 (PGE2) may impair beta-cell function. Using NOS inhibitor N(G)-monomethyl-L-arginine (L-NMMA), we have further investigated the relation between NO formation and COX-2 expression. IL-1beta stimulated the formation of NO and PGE2 by pancreatic beta-cells. L-NMMA completely inhibited IL-1beta-induced NO formation and attenuated PGE2 production. COX-2 gene transcription level and protein expression were determined by real-time PCR, Western blot and luciferase analysis. L-NMMA inhibited IL-1beta-induced promoter activity, gene transcription and protein expression of COX-2 in pancreatic beta-cells. Therefore, we concluded that NO-affected COX-2 activity is directly linked to COX-2 gene transcription and protein expression in pancreatic beta-cells. The identification of a novel interaction of NO on the COX signaling pathway in beta-cells provides a strategy of intervention for further evaluating the role of NO and PGE2 in autoimmune diabetes.

Animals↗

PubMed2005

[Effect of Shuangshen Tongguan Recipe on nuclear factor-kappa B signal pathway and myocardial junction-mediated intercellular communication in acute myocardial ischemia/reperfusion injured model rats].

OBJECTIVE: To investigate the effects of Shuangshen Tongguan Recipe (SSTG) on myocardial nuclear factor-kappa B (NF-kappaB) signal pathway, expression of myocardial junction intercellular communication (MJIC) connexin 43 (Cx43), and infarcted myocardial size and weight of the rats' heart after acute myocardial ischemia/reperfusion (I/R) damage. METHODS: Model rat of I/R injury was established by coronary arterial ligating/ releasing. The infarcted myocardial size and weight were determined by N-BT staining, expression of NF-kappaB p65 in myocardial tissue and Cx43 were determined by immunohistochemical method, contents of serum tumor necrosis factor-alpha(TNF-alpha) and intercellular adhesion molecule-1 (ICAM-1) were measured by ABC-ELISA. RESULTS: The myocardial infarcted size and weight, expression of NF-kappaB p65, contents of serum TNF-alpha and ICAM-1 of I/R injured rats in the model group were significantly increased (P<0.05), while Cx43 degraded markedly after modeling. These changes were restored after treated with SSTG (P <0.05). CONCLUSION: Serious myocardial infarction occurs after ischemia/reperfusion injury, combined with NF-kappaB signal pathway activation and severe Cx43 degradation. SSTG could inhibit the activation of NF-kappaB, the over-excretion of TNF-alpha and ICAM-1 in serum, and the degradation of Cx43 to decrease the myocardial infarcted size and weight.

Animals↗

PubMed2004

Validation of semiautomated methods for quantifying cingulate cortical metrics in schizophrenia.

This paper validates semiautomated methods for reconstructing cortical surfaces of the cingulate gyrus from high-resolution magnetic resonance (MR) images. Bayesian segmentation was used to delineate the image voxels into five tissue types: cerebrospinal fluid (CSF), gray matter (GM), white matter (WM), and partial volumes of CSF/GM and GM/WM; the tissues were then recalibrated as CSF, GM, and WM via the Neyman-Pearson Likelihood Ratio Test. To generate cortical surfaces at the interface of GM and WM, the thresholds between the tissue types were first used to reassign partial volume voxels to CSF, GM, and WM with minimum error (that varied from 0.06 to 0.15 for the 10 subjects). Next, topology-correct cortical surfaces were generated and validated with almost all surface vertices lying within one voxel (0.5 mm) of hand contours. Dynamic programming was used to delineate and extract the cingulate gyrus from the cortical surfaces based on its gyral and sulcal boundaries. The intraclass correlation coefficient for surface area obtained by two raters for all 10 surfaces was 0.82. In addition, by repeating the entire procedure three times in one subject, we obtained a coefficient of variation of 0.0438 for surface area.

Adult↗

PubMed2004

Isolation of high purity 1-[2',4'-dihydroxy-3',5'-di-(3"-methylbut-2"-enyl)-6'-methoxy] phenylethanone from Acronychia pedunculata (L.) Miq. by high-speed counter-current chromatography.

Following an initial clean-up step on silica, high-speed counter-current chromatography (HSCCC) was used to purify an aryl ketone, 1-[2',4'-dihydroxy-3',5'-di-(3"-methylbut-2"-enyl)-6'-methoxy] phenylethanone from an extract of the stem bark of the shrub Acronychia pedunculata. The two-phase solvent system used was composed of n-heptane-ethyl acetate-methanol-water at an optimized volume ratio of 4:1:4:1 (v/v/v/v). Target compound (58.1 mg) with a purity of 98.9% was obtained after HSCCC of 183.5 mg sample with a purity of 35.7% recovered after the silica clean-up step. Identification of the target compound was performed by 1H NMR, 13C NMR, two-dimensional NMR and LC-electrospray ionization MS.

Alkenes↗

PubMed2004

CRUISE: cortical reconstruction using implicit surface evolution.

Segmentation and representation of the human cerebral cortex from magnetic resonance (MR) images play an important role in neuroscience and medicine. A successful segmentation method must be robust to various imaging artifacts and produce anatomically meaningful and consistent cortical representations. A method for the automatic reconstruction of the inner, central, and outer surfaces of the cerebral cortex from T1-weighted MR brain images is presented. The method combines a fuzzy tissue classification method, an efficient topology correction algorithm, and a topology-preserving geometric deformable surface model (TGDM). The algorithm is fast and numerically stable, and yields accurate brain surface reconstructions that are guaranteed to be topologically correct and free from self-intersections. Validation results on real MR data are presented to demonstrate the performance of the method.

Algorithms↗

PubMed2004

Cortical surface segmentation and mapping.

Segmentation and mapping of the human cerebral cortex from magnetic resonance (MR) images plays an important role in neuroscience and medicine. This paper describes a comprehensive approach for cortical reconstruction, flattening, and sulcal segmentation. Robustness to imaging artifacts and anatomical consistency are key achievements in an overall approach that is nearly fully automatic and computationally fast. Results demonstrating the application of this approach to a study of cortical thickness changes in aging are presented.

Aging↗

PubMed2004

Dynamic behavior of fragile X full mutations in cultured female fetal fibroblasts.

AIM: To assess mitotic stability of the fragile X full mutations and its relationship with DNA methylation. METHODS: The length change of the expanded CGG repeats was examined and correlated it with the methylation status in the DNA samples isolated from the fibroblasts derived from a fragile X female fetus and a fragile X male adult, respectively. RESULTS: A dramatic instability of the expanded CGG repeats in the female fetal fibroblasts was observed. Southern blot analysis revealed that the 6.9-kb major expanded band detected in passage 2 was completely replaced by a 7.7-kb band after passage 30. Fibroblast clones derived from the passage 3 displayed an unstable expansion of the CGG repeat during clonal proliferation, while methylation status of the CGG repeat region was maintained. In contrast, in fragile X male fibroblasts the expanded CGG repeats were stable during clonal proliferation. CONCLUSION: The mitotic instability of expanded CGG repeat is not always restricted in early development window as proposed previously and other elements rather than DNA methylation could affect the stability of the expanded CGG repeats in fragile X female fetal fibroblast cells.

Adult↗

PubMed2004

[Effects of shuangshen tongguan (SSTG) on TNF-alpha, ICAM-1 during myocardial ischemia-reperfusion injury].

OBJECTIVE: To observe the effects of SSTG on infarction size and tumor necrosis factor-alpha (TNF-alpha), intercellular adhesion molecular-1 (ICAM-1) levels in serum during reperfusion injury of acute myocardial ischemia. METHOD: Anterior descending branch of coronary artery was ligated and released to create myocardial ischemia-reperfusion injury. The size and weight of infarction area and the contents of TNF-alpha, IGAM-1 in serum were assayed by N-BT staining and ELISA respectively. RESULT: The size and weight of infarct area and the contents of TNF-alpha, ICAM-1 in serum were significantly increased compared with the normal group and were obviously decreased after being treated with SSIG. CONCLUSION: Ischemia-reperfusion stimulated the secretion of TNF-alpha and ICAM-1, which play an important role in ischemia-reperfusion injury. SSTG might protect myocardium from ischemia-reperfusion injury by suppressing over-secretion of TNF-alpha and ICAM-1 and reducing the size and weight of infarction area.

Animals↗

PubMed2003

Herpes simplex virus type 1 DNA is immunostimulatory in vitro and in vivo.

Recently, prokaryotic DNAs containing unmethylated CpG motifs have been shown to be intrinsically immunostimulatory both in vitro and in vivo, tending to promote Th1-like responses. In contrast, CpG dinucleotides in mammalian DNAs are extensively methylated on cytosines and hence immunologically inert. Since the herpes simplex virus (HSV) genome is unmethylated and G+C rich, we predicted that CpG motifs would be highly prevalent in the HSV genome; hence, we examined the immunostimulatory potential of purified HSV DNA in vitro and in vivo. Mouse splenocyte cultures treated with HSV DNA or HSV-derived oligodeoxyribonucleotides (ODNs) showed strong proliferative responses and production of inflammatory cytokines (gamma interferon [IFN-gamma], tumor necrosis factor [TNF], and interleukin-6 [IL-6]) in vitro, whereas splenocytes treated with mammalian CV-1 DNA or non-CpG ODN did not. After immunization with ovalbumin (OVA), only splenocytes from mice immunized with HSV DNA or HSV-ODN as the adjuvants proliferated strongly and produced typical Th1 responses, including CD8(+) cytotoxic T-lymphocyte responses, upon restimulation with OVA. Furthermore, HSV-ODN synergized with IFN-gamma to induce nitric oxide (NO), IL-6, and TNF production from macrophages. These results demonstrate that HSV DNA and HSV-ODN are immunostimulatory, driving potent Th1 responses both in vitro and in vivo. Considering that HSV DNA has been found to persist in nonneuronal cells, these results fuel speculation that HSV DNA might play a role in pathogenesis, in particular, in diseases like herpes stromal keratitis (HSK) that involve chronic inflammatory responses in the absence of virus or viral antigens.

Adjuvants, Immunologic↗

PubMed2002

Separation of salidroside from Rhodiola crenulata by high-speed counter-current chromatography.

High-speed counter-current chromatography (HSCCC) was used to purify salidroside from an extract of Rhodiola crenulata with two steps using a two-phase solvent system composed of ethyl acetate-n-butanol-water (1:4:5, v/v) in the first run and chloroform-methanol-isopropanol-water (5:6:1:4) in the second run. The method yielded 21.9 mg of salidroside from 1.216 g of the crude sample at 98% purity determined by HPLC analyses. Identification was performed by 1H NMR, 13C NMR, and MS.

Countercurrent Distribution↗

PubMed2002

Automated sulcal segmentation using watersheds on the cortical surface.

The human cortical surface is a highly complex, folded structure. Sulci, the spaces between the folds, define location on the cortex and provide a parcellation into anatomically distinct areas. A topic that has recently received increased attention is the segmentation of these sulci from magnetic resonance images, with most work focusing on extracting either the sulcal spaces between the folds or curve representations of sulci. Unlike these methods, we propose a technique that extracts actual regions of the cortical surface that surround sulci, which we call "sulcal regions." The method is based on a watershed algorithm applied to a geodesic depth measure on the cortical surface. A well-known problem with the watershed algorithm is a tendency toward oversegmentation, meaning that a single region is segmented as several pieces. To address this problem, we propose a postprocessing algorithm that merges appropriate segments from the watershed algorithm. The sulcal regions are then manually labeled by simply selecting the appropriate regions with a mouse click and a preliminary study of sulcal depth is reported. Finally, a scheme is presented for computing a complete parcellation of the cortical surface.

Automation↗

PubMed2002

Topology correction in brain cortex segmentation using a multiscale, graph-based algorithm.

Reconstructing an accurate and topologically correct representation of the cortical surface of the brain is an important objective in various neuroscience applications. Most cortical surface reconstruction methods either ignore topology or correct it using manual editing or methods that lead to inaccurate reconstructions. Shattuck and Leahy recently reported a fully automatic method that yields a topologically correct representation with little distortion of the underlying segmentation. We provide an alternate approach that has several advantages over their approach, including the use of arbitrary digital connectivities, a flexible morphology-based multiscale approach, and the option of foreground-only or background-only correction. A detailed analysis of the method's performance on 15 magnetic resonance brain images is provided.

Algorithms↗

PubMed2002

Induction of cyclooxygenase-2 gene in pancreatic beta-cells by 12-lipoxygenase pathway product 12-hydroxyeicosatetraenoic acid.

Cyclooxygenase-2 (COX-2) gene and 12-lipoxygenase (12-LO) gene are preferentially expressed over other types of cyclooxygenase and lipoxygenase in pancreatic beta-cells. Inhibition of either COX-2 or 12-LO can prevent cytokine-induced pancreatic beta-cell dysfunction as defined by inhibition of glucose-stimulated insulin secretion. As cellular stress induces both genes and their respective end products in pancreatic beta-cells, we evaluated the role of 12-hydroxyeicosatetraenoic acid (HETE) on COX-2 gene expression, protein expression, and prostaglandin E2 (PGE2) production. We demonstrate that 12-HETE significantly increases COX-2 gene expression and consequent product formation, whereas a closely related lipid, 15-HETE, does not. In addition, IL-1beta-stimulated prostaglandin E2 production is completely inhibited by a preferential lipoxygenase inhibitor cinnaminyl-3,4-dihydroxy-alpha-cyanocinnamate. We then evaluated IL-1beta-induced PGE2 production in islets purified from control C57BL/6 mice and 12-LO knockout mice lacking cytokine-inducible 12-HETE. IL-1beta stimulated an 8-fold increase in PGE2 production in C57BL/6 islets but failed to stimulate PGE2 in 12-LO knockout islets. Addition of 12-HETE to 12-LO knockout islet cells produced a statistically significant rise in PGE2 production. Furthermore, 12-HETE, but not 15-HETE, stimulated COX-2 promoter and activator protein-1 binding activity. These data demonstrate that 12-HETE mediates cytokine-induced COX-2 gene transcription and resultant PGE2 production in pancreatic beta-cells.

12-Hydroxy-5,8,10,14-eicosatetraenoic Acid↗