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Biomedical subjects

W Qu

Publications and source records attributed to W Qu.

At least 37 records · Page 2Linked to original sources

Blockade of RAGE-amphoterin signalling suppresses tumour growth and metastases.

The receptor for advanced glycation end products (RAGE), a multi-ligand member of the immunoglobulin superfamily of cell surface molecules, interacts with distinct molecules implicated in homeostasis, development and inflammation, and certain diseases such as diabetes and Alzheimer's disease. Engagement of RAGE by a ligand triggers activation of key cell signalling pathways, such as p21ras, MAP kinases, NF-kappaB and cdc42/rac, thereby reprogramming cellular properties. RAGE is a central cell surface receptor for amphoterin, a polypeptide linked to outgrowth of cultured cortical neurons derived from developing brain. Indeed, the co-localization of RAGE and amphoterin at the leading edge of advancing neurites indicated their potential contribution to cellular migration, and in pathologies such as tumour invasion. Here we demonstrate that blockade of RAGE-amphoterin decreased growth and metastases of both implanted tumours and tumours developing spontaneously in susceptible mice. Inhibition of the RAGE-amphoterin interaction suppressed activation of p44/p42, p38 and SAP/JNK MAP kinases; molecular effector mechanisms importantly linked to tumour proliferation, invasion and expression of matrix metalloproteinases.

Animals↗

Very negative potential for half-inactivation of, and effects of anions on, voltage-dependent sodium currents in acutely isolated rat olfactory receptor neurons.

Previous measurements with CsF pipette solutions using whole-cell patch-clamp techniques in dissociated rat olfactory receptor neurons (ORNs) indicated that the sodium currents had very negative inactivation characteristics with the implication that the cell resting potential must also normally have a very negative value. This study supports the conclusions that such an effect was real and not dependent on either the nature of the pipette anions or the recording situation previously used. For all pipette solutions, sodium currents showed a threshold activation approximately -80 mV and half-maximal activation voltages approximately -55 with half-inactivation potential < or =-100 mV, without being significantly affected by the replacement of F(-) by other pipette anions (H(2)PO(-)(4) and acetate(-)) or the addition of nucleotides and glutathione (which did cause a very slight positive shift). F(-), followed by H(2)PO(-)(4) and to a much lesser extent by acetate(-), was the most favorable pipette anion for obtaining good seals and whole-cell sodium currents in these extremely small ORNs. These results implied that resting potentials, for viable responsive cells, should be more negative than about -90 mV, as supported by the observation that action potentials could only be evoked from holding potentials more negative than -90 mV.

Acetates↗

A Model for Overlapped EDL Fields.

A model to determine the electrical potential and ionic concentration distributions in the overlapped EDL fields between two infinitely large flat plates was developed in this paper. It was found that the treatment in the classical theory may lead to an inaccurate description due to the misuse of the Boltzmann equation. New governing equations for such an overlapped EDL field were derived. The potential distribution and ionic concentration distributions for inorganic oxide-aqueous solution systems were calculated. The results were compared with the predictions of the classical theory. Differences between our model and the classical treatment were found, especially at small separation distance. Copyright 2000 Academic Press.

Journal Article↗

[Study on the effect of alcohol on embryonic development by using in vitro post-implantation rat whole embryo culture].

In order to explore the effects of drinking alcohol during pregnancy on embryonic development and its mechanisms, a post-implantation whole embryo culture(WEC) technique was used. The 9.5 day rat embryos were explanted in rat serum medium(immediately centrifugal serum, ICS) with alcohol(0.0.4.1.0, 2.00 and 4.00 g/L), and cultured for 48 hours. The index of embryo development and morphological scores induced by alcohol were observed. The result showed that alcohol had obviously effects on the development and growth of embryos with a dose-response relationship. Embryonic development of 0.4 g/L group was not significantly different from the control group, whereas 1.0 g/L group could interfere with the development score of mid-brain, forebrain, neurotube, and visceral yolk sac(VYS) circle obviously. All scores of the 2.00 g/L group were significantly lower than that of control group (P < 0.05). Moreover, the rate of embryo lethality and teratogenecity were obvious increased. It is concluded that alcohol has developmental toxicity and teratogenicity. The target organ affected by alcohol is brain. The effects of alcohol on the developmental differentiation of visceral yolk sac and DNA synthesis are probably related to its developmental abnormalities.

Animals↗

p53 accumulation due to down-regulation of ubiquitin: relevance for neuronal apoptosis.

The p53 tumor suppressor protein is a major regulator of cell growth arrest and apoptosis in response to DNA damage. Both p53 function and stability are tightly controlled by Mdm2, which binds to the p53 N-terminus and targets p53 for ubiquitin-mediated proteolysis. Previous studies suggest that adrenalectomy-induced neuronal apoptosis is p53-dependent. Here we demonstrate both nuclear accumulation and functional activation of p53 protein in apoptotic hippocampal neurons from adrenalectomized rats. Increased p53 expression occurred despite the accumulation of its negative regulator, Mdm2, and the formation of p53-Mdm2 complexes. The persistence of p53 expression was explained by a striking decrease in free ubiquitin in p53-positive neurons. The addition of exogenous ubiquitin to p53-Mdm2 complexes from apoptotic neurons restored p53 degradation. These findings demonstrate a novel mechanism of p53 stabilization mediated by decreased ubiquitin levels. Regulation of free ubiquitin may therefore be an effective way to modulate p53-dependent apoptosis in certain cell types.

Adrenalectomy↗

Blockade of RAGE suppresses periodontitis-associated bone loss in diabetic mice.

Diabetes is associated with increased prevalence, severity, and progression of periodontal disease. To test the hypothesis that activation of RAGE (Receptor for Advanced Glycation End products) contributes to the pathogenesis of diabetes-associated periodontitis, we treated diabetic mice, infected with the human periodontal pathogen Porphyromonas gingivalis, with soluble RAGE (sRAGE). sRAGE is the extracellular domain of the receptor, which binds ligand and blocks interaction with, and activation of, cell-surface RAGE. Blockade of RAGE diminished alveolar bone loss in a dose-dependent manner. Moreover, we noted decreased generation of the proinflammatory cytokines TNF-alpha and IL-6 in gingival tissue, as well as decreased levels of matrix metalloproteinases. Gingival AGEs were also reduced in mice treated with sRAGE, paralleling the observed suppression in alveolar bone loss. These findings link RAGE and exaggerated inflammatory responses to the pathogenesis of destructive periodontal disease in diabetes.

Alveolar Bone Loss↗

[Studies on the mechanisms of developmental toxicity of alcohol].

OBJECTIVE: To study the mechanisms of developmental toxicity in animals induced by ethyl alcohol. METHOD: Rat embryos of 9.5 days of gestation were exposed to different doses of ethyl alcohol in vitro. Postimplantation whole embryo culture and fluorescence polarization technique were used to investigate the effects of alcohol on embryo development and visceral yolk sac (VYS) membrane lipid fluidity. RESULT: 400 mg alcoho/L caused no significant differences to embryo development, organ morphological scores, polarization (Pr value) and lipid fluidity unit (LFU), as compared with the non-alcohol treated controls. 1,000 mg alcohol/L led to the decrease of scores of brain, VYS circle, neurotube, head length and heart, as well as DNA and Pr value; whereas LFU values were increased significantly. Above 2,000 mg alcohol/L, all indexes were decreased except LFU of VYS cell membrane. Alcohol significantly elevated lipid fluidity of VYS cell membrane. CONCLUSIONS: Alcohol causes development toxicity and teratogenisis in rats. Brain and VYS are the targets of alcohol effect. Its development toxicity is related with lipid fluidity and the VYS membrane damage.

Abnormalities, Multiple↗

99mTc-HL91 "hot spot" imaging of mice bearing human carcinoma by gamma camera and the effects of tumor necrosis on imaging.

OBJECTIVE: To evaluate the hypoxia-avid agent 99mTc-HL91 (99mTc labeled 4, 9-diaza-3, 3, 10, 10-tetramethyldodecan-2, 11-dione dioxime) as the tracer of tumor "hot spot" imaging and the influence of tumor necrosis on the image. METHODS: After injection of 99mTc-HL91, 6 nude mice bearing human breast cancer MCF-7 and 18 nude mice bearing human pancreatic adenocarcinoma were subjected to gamma camera imaging, postmortem analysis, and autoradiography and imaging of tumor sections. RESULTS: The image of tumor was identified 1 hour after injection of 99mTc-HL91. Images demonstrated gradually increased 99mTc-HL91 uptake in the tumor 1-12 hours after injection (P < 0.05-0.001). Six hours after injection, the radioactivity ratios of tumor to thorax and tumor to head were higher than 2.1. Six hours after injection, the radioactivity ratios of tumor to brain, muscle, blood, heart, lung and kidney in pancreatic adenocarcinoma bearing nude mice were 101.0 +/- 114.7, 30.0 +/- 30.3, 19.9 +/- 21.9, 14.4 +/- 15.1, 3.71 +/- 2.41 and 0.46 +/- 0.26, respectively, and the radioactivity ratios in breast cancer MCF-7 bearing nude mice were close to these figures. The radioactivity of non-necrotic tumor was 3.77 times that of necrotic tumor. However, the radioactivity ratios of tumor to liver, intestine and stomach were lower than 1.3. Autoradiographs and images of tumor sections showed that the radioactivity was higher in the region of solid tumor than in the necrotic region. CONCLUSION: 99mTc-HL91 via gamma camera positively identifies regional tumor in nude mice bearing human cancer. 99mTc-HL91 retention is lower in necrotic tumor than in non-necrotic tumor. The low radioactivity ratio of tumor to abdominal organs limits the application of 99mTc-HL91 in detecting abdominal tumors.

Adenocarcinoma↗

N(epsilon)-(carboxymethyl)lysine adducts of proteins are ligands for receptor for advanced glycation end products that activate cell signaling pathways and modulate gene expression.

Recent studies suggested that interruption of the interaction of advanced glycation end products (AGEs), with the signal-transducing receptor receptor for AGE (RAGE), by administration of the soluble, extracellular ligand-binding domain of RAGE, reversed vascular hyperpermeability and suppressed accelerated atherosclerosis in diabetic rodents. Since the precise molecular target of soluble RAGE in those settings was not elucidated, we tested the hypothesis that predominant specific AGEs within the tissues in disorders such as diabetes and renal failure, N(epsilon)-(carboxymethyl)lysine (CML) adducts, are ligands of RAGE. We demonstrate here that physiologically relevant CML modifications of proteins engage cellular RAGE, thereby activating key cell signaling pathways such as NF-kappaB and modulating gene expression. Thus, CML-RAGE interaction triggers processes intimately linked to accelerated vascular and inflammatory complications that typify disorders in which inflammation is an established component.

Animals↗

[New method for the isolation of astroglial cells and oligodendrocytes].

Based on the different properties of cellular adhesions, developmental time-courses and growth pattern of astroglial cells and oligodendrocytes, a method of isolating glial cells in vitro was developed. The observations under inverted light microscope and scan electronic microscope identified that the morphology of isolated cells were consistent with the previous description. Immunocytochemical examination showed the expressions of markers, the glial fibrillary acidic protein (GFAP) of astroglia cells and the myelin basic protein (MBP) of oligodendrocytes were consistent with the isolated cells. All parameters showed that the isolated glial cells were pure, and the new methods were easy and reliable.

Animals↗

RAGE mediates a novel proinflammatory axis: a central cell surface receptor for S100/calgranulin polypeptides.

S100/calgranulin polypeptides are present at sites of inflammation, likely released by inflammatory cells targeted to such loci by a range of environmental cues. We report here that receptor for AGE (RAGE) is a central cell surface receptor for EN-RAGE (extracellular newly identified RAGE-binding protein) and related members of the S100/calgranulin superfamily. Interaction of EN-RAGEs with cellular RAGE on endothelium, mononuclear phagocytes, and lymphocytes triggers cellular activation, with generation of key proinflammatory mediators. Blockade of EN-RAGE/RAGE quenches delayed-type hypersensitivity and inflammatory colitis in murine models by arresting activation of central signaling pathways and expression of inflammatory gene mediators. These data highlight a novel paradigm in inflammation and identify roles for EN-RAGEs and RAGE in chronic cellular activation and tissue injury.

Amino Acid Sequence↗

Molecular cloning, enzymatic characterization, developmental expression, and cellular localization of a mouse cytochrome P450 highly expressed in kidney.

A cDNA encoding a new cytochrome P450 was isolated from a mouse liver library. Sequence analysis reveals that this 1,886-base pair cDNA encodes a 501-amino acid polypeptide that is 69-74% identical to CYP2J subfamily P450s and is designated CYP2J5. Recombinant CYP2J5 was co-expressed with NADPH-cytochrome P450 oxidoreductase in Sf9 cells using a baculovirus system. Microsomal fractions of CYP2J5/NADPH-cytochrome P450 oxidoreductase-transfected cells metabolize arachidonic acid to 14,15-, 11,12-, and 8, 9-epoxyeicosatrienoic acids and 11- and 15-hydroxyeicosatetraenoic acids (catalytic turnover, 4.5 nmol of product/nmol of cytochrome P450/min at 37 degrees C); thus CYP2J5 is enzymologically distinct. Northern analysis reveals that CYP2J5 transcripts are most abundant in mouse kidney and present at lower levels in liver. Immunoblotting using a polyclonal antibody against a CYP2J5-specific peptide detects a protein with the same electrophoretic mobility as recombinant CYP2J5 most abundantly in mouse kidney microsomes. CYP2J5 is regulated during development in a tissue-specific fashion. In the kidney, CYP2J5 is present before birth and reaches maximal levels at 2-4 weeks of age. In the liver, CYP2J5 is absent prenatally and during the early postnatal period, first appears at 1 week, and then remains relatively constant. Immunohistochemical staining of kidney sections with anti-human CYP2J2 IgG reveals that CYP2J protein(s) are present primarily in the proximal tubules and collecting ducts, sites where the epoxyeicosatrienoic acids are known to modulate fluid/electrolyte transport and mediate hormonal action. In situ hybridization confirms abundant CYP2J5 mRNA within tubules of the renal cortex and outer medulla. Epoxyeicosatrienoic acids are endogenous constituents of mouse kidney thus providing direct evidence for the in vivo metabolism of arachidonic acid by the mouse renal epoxygenase(s). Based on these data, we conclude that CYP2J5 is an enzymologically distinct, developmentally regulated, protein that is localized to specific nephron segments and contributes to the oxidation of endogenous renal arachidonic acid pools. In light of the well documented effects of epoxyeicosatrienoic acids in modulating renal tubular transport processes, we postulate that CYP2J5 products play important functional roles in the kidney.

Amino Acid Sequence↗

[Effects of alcohol on membrane lipid fluidity of astrocytes and oligodendrocytes].

To explore the mechanism of neuron development retardation and myelination abnormality caused by alcohol, the membrane lipid fluidity of astrocytes and oligodendrocytes which is related to neuron and myelin development were measured by using DPH fluorescence probe. The results showed that 5 mmol/L alcohol could lead to decrease the polarization of fluorescence (Pr) and increase the lipid fluidity unit of membrane in both cells. The alteration was in obvious dose-response relationship. The effect of alcohol on astrocytes was stronger than that of oligodendrocytes. It indicated that alcohol could change lipid fluidity of cell membrane. Alcohol probably plays major role in the dysfunction of astrocytes and oligodendrocytes.

Animals↗

An absorbable pinned-ring device for microvascular anastomosis of vein grafts: experimental studies.

In the rabbit, posterior facial vein segments were grafted to the femoral arteries using either conventional suture technique or a mechanical absorbable pinned-ring device. The purpose of this study was to compare patency rates and anastomotic times for the two different methods. The anastomoses were evaluated macroscopically and using light and scanning electron microscopy. The grafts anastomosed with the absorbable rings exhibited 100% patency, while only 83% of the sutured grafts were patent. The mean anastomotic time using the mechanical pinned-ring device was 18.1 min (range 9.8-30 min). The conventionally sutured anastomoses were completed in a mean time of 60 min (range 50-75 min). The experiment has confirmed that the absorbable pinned-ring device provides a safe and fast way to perform microvascular anastomosis.

Absorbable Implants↗

P450 subfamily CYP2J and their role in the bioactivation of arachidonic acid in extrahepatic tissues.

Historically, there has been intense interest in P450 metabolic oxidation, peroxidation, and reduction of xenobiotics. More recently, there has been a growing appreciation for the role of P450s in the oxidation of lipophilic endobiotics, such as bile acids, fat-soluble vitamins, and eicosanoids. This review details the emerging CYP2J subfamily of P450s and their role as catalysts of arachidonic acid metabolism.

Animals↗

PGE(2) stimulates O(2) uptake in hepatic parenchymal cells: involvement of the cAMP-dependent protein kinase.

The aim of this study was to determine which PGE(2) receptors and signal transduction pathways are responsible for the stimulation of oxygen uptake in liver. Hepatic parenchymal cells isolated from female Sprague-Dawley rats were incubated either with PGE(2), 17-phenyl-omega-trinor PGE(2) (an EP(1)-specific agonist), or 11-deoxy PGE(1) (an EP(2)/EP(4)-specific agonist), and oxygen consumption was measured. Both PGE(2) and 11-deoxy PGE(1) stimulated oxygen consumption. However, an EP(1) agonist was without effect. Although PGE(2) elevated intracellular calcium, this occurred at concentrations approximately 500-fold lower than that required to stimulate oxygen uptake. PGE(2)-stimulated increases in cAMP formation correlated well with the increase in oxygen consumption. Dibutyryl cAMP also increased oxygen consumption. Furthermore, N-[2-(p-bromocinnamylamino)ethyl]-5-isoquinolinesulfonamide, a cell-permeable inhibitor of protein kinase A (PKA), reduced the stimulation of oxygen uptake by PGE(2). Incubation of isolated parenchymal cell mitochondria with the purified catalytic subunit of PKA and ATP increased both state 3 rates of oxygen uptake and the respiratory control ratio by approximately 50%. Activation of these events was prevented by incubation with the PKA inhibitory peptide, PKI. These findings are consistent with the hypothesis that PGE(2) stimulates oxygen consumption via an EP(2) and/or EP(4) subclass of receptors through the actions of cAMP on a cAMP-dependent protein kinase.

1-Methyl-3-isobutylxanthine↗

Allergic lung responses are increased in prostaglandin H synthase-deficient mice.

To investigate the function of prostaglandin H synthase-1 and synthase-2 (PGHS-1 and PGHS-2) in the normal lung and in allergic lung responses, we examined allergen-induced pulmonary inflammation and airway hyperresponsiveness in wild-type mice and in PGHS-1(-/-) and PGHS-2(-/-) mice. Among nonimmunized saline-exposed groups, we found no significant differences in lung function or histopathology, although PGE(2) was dramatically reduced in bronchoalveolar lavage (BAL) fluid from PGHS-1(-/-) mice, relative to wild-type or PGHS-2(-/-) mice. After ovalbumin sensitization and challenge, lung inflammatory indices (BAL cells, proteins, IgE, lung histopathology) were significantly greater in PGHS-1(-/-) mice compared with PGHS-2(-/-) mice, and both were far greater than in wild-type mice, as illustrated by the ratio of eosinophils in BAL fluid (8:5:1, respectively). Both allergic PGHS-1(-/-) and PGHS-2(-/-) mice exhibited decreased baseline respiratory system compliance, whereas only allergic PGHS-1(-/-) mice showed increased baseline resistance and responsiveness to methacholine. Ovalbumin exposure caused a modest increase in lung PGHS-2 protein and a corresponding increase in BAL fluid PGE(2) in wild-type mice. We conclude that (a) PGHS-1 is the predominant enzyme that biosynthesizes PGE(2) in the normal mouse lung; (b) PGHS-1 and PGHS-2 products limit allergic lung inflammation and IgE secretion and promote normal lung function; and (c) airway inflammation can be dissociated from the development of airway hyperresponsiveness in PGHS-2(-/-) mice.

Allergens↗

[Distribution of genotypes of alcohol dehydrogenase 2 and aldehyde dehydrogenase 2 in Japanese twin children].

OBJECTIVE: In order to prevent alcohol related deseases, this study investigated the distribution of the genes controlling alcohol metabolism in Japan's twin. METHODS: Restriction fragment length polymorphism-polymerase chain reaction (RFLP-PCR) technique was used to measure the control gene of alcohol metabolized enzymes and the genotypes of alcohol dehydrogenase 2 (ADH2) and aldehyde dehydrogenase 2 (ALDH2), which were distributed in Japan's twins. At the same time, according to the difference in genotypes, the sensitive individuals were screened from the study subjects. RESULTS: The distribution of ADH2 and ALDH2 genes were consistent with the Hardy-weinberg equation. The three genotypes of ADH2 gene were ADH2(1)/ADH2(1) (1.1%), ADH2(1)/ADH2(2) (44.6%) and ADH2(2)/ADH2(2) (54.3%). And those of ALDH2 gene were ALDH2(1)/ALDH2(1) (41.3%), ALDH2(1)/ALDH2(2) (39.1%) and ALDH2(2)/ALDH2(2) (19.6%). The frequency of ADH2 and ALDH2 genes was 0.255, 0.745 and 0.609, 0.391 respectively. CONCLUSION: Not only the distribution of genotypes of ADH2 and ALDH2 is known, but also the sensitive individuals are found, which can help prevent alcohol related disease.

Alcohol Dehydrogenase↗