Biomedical subjects

Mingyao Liu

Publications and source records attributed to Mingyao Liu.

At least 73 records · Page 4Linked to original sources

PubMed2004

Increased expression of nitric oxide synthase in human lung transplants after nitric oxide inhalation.

BACKGROUND: The effects of the ischemia-reperfusion process of organ transplantation on nitric oxide (NO) synthase (NOS) in humans are unknown. The effects of NO inhalation on endogenous NOS expression and activity are controversial. The authors hypothesized that NO inhalation may affect ischemia-reperfusion-induced alterations of the endogenous NOS system. METHODS: The authors performed lung biopsy on patients in a randomized phase II clinical trial of NO inhalation during lung transplantation. After lung implantation, 20 ppm of NO or placebo gas was administered 10 min after the start of reperfusion. Lung tissues were collected from 20 patients (NO, n=9; placebo, n=11) after cold and warm ischemia, 1 hr and 2 hr after reperfusion. The protein levels of NOS isoforms were analyzed by Western blotting and the total NOS activity was measured. RESULTS: The protein levels of inducible NOS did not change significantly in either of the groups. In contrast, during the 2-hr reperfusion period, constitutive NOS (neuronal NOS [nNOS] and endothelial NOS) tended to decrease in the placebo group, but gradually increased in the NO group. After 2 hr of reperfusion, the nNOS protein in the NO group was significantly higher than that in the placebo group (P <0.05). However, the total NOS activity remained at low levels in both groups. CONCLUSIONS: NO inhalation-induced increase of constitutive NOS proteins indicates the interaction between inhaled NO molecules and lung tissues. However, the activity of these newly synthesized NOS proteins remains suppressed during the ischemia-reperfusion period of lung transplantation.

Administration, Inhalation↗

PubMed2004

Intercellular adhesion molecule-1 mediates cellular cross-talk between parenchymal and immune cells after lipopolysaccharide neutralization.

The mechanisms by which parenchymal cells interact with immune cells, particularly after removal of LPS, remain unknown. Lung explants from rats, mice deficient in the TNF gene, or human lung epithelial A549 cells were treated with LPS and washed, before naive alveolar macrophages, bone marrow monocytes, or PBMC, respectively, were added to the cultures. When the immune cells were cocultured with LPS-challenged explants or A549 cells, TNF production was greatly enhanced. This was not affected by neutralization of LPS with polymyxin B. The LPS-induced increase in the expression of ICAM-1 on A549 cells correlated with TNF production by PBMC. The cellular cross talk leading to the TNF response was blunted by an anti-ICAM-1 Ab and an ICAM-1 antisense oligonucleotide. In A549 cells, a persistent decrease in the concentration of intracellular cAMP was associated with colocalization of LPS into Toll-like receptor 4 and the Golgi apparatus, resulting in increased ICAM-1 expression. Inhibition of LPS internalization by cytochalasin D or treatment with dibutyryl cAMP attenuated ICAM-1 expression and TNF production by PBMC. In conclusion, lung epithelial cells are not bystanders, but possess memory of LPS through the expression of ICAM-1 that interacts with and activates leukocytes. This may provide an explanation for the failure of anti-LPS therapies in sepsis trials.

Animals↗

PubMed2004

A novel model to study bacterial adherence to the transplanted airway: inhibition of Burkholderia cepacia adherence to human airway by dextran and xylitol.

BACKGROUND: Lung infection with Burkholderia cepacia complex before lung transplantation in patients with cystic fibrosis is a major risk factor for decreased post-operative survival rates compared with those of patients colonized with the more common opportunistic pathogen Pseudomonas aeruginosa. Because adherence to mucosal surfaces is an important initial step in infection, we investigated the use of non-toxic neutral polysaccharides and a sugar alcohol to prevent adherence of B cepacia complex to allograft airway epithelium. METHODS: We used human airway explants prepared from donor tracheobronchial tissue to test the effect of dextrans and xylitol in inhibiting the binding of Burkholderia cepacia complex. We used immunofluorescence and electron microscopy to determine the distribution of bacteria in the explants. RESULTS: Burkholderia cepacia complex bound to the explants and was found only in the surface mucus layer. Dextran 40 kd applied before adding the bacteria decreased the number of bound organisms by 80% to 99%. Smaller molecular mass dextrans (4 and 20 kd) were ineffective. Xylitol inhibited bacterial binding by 67% to 85%. Both agents seemed to decrease the thickness of the surface mucus, suggesting that they may indirectly inhibit bacterial binding by removing adherent surface mucus. CONCLUSIONS: Treating donor lungs with dextran 40 kd or xylitol before (and possibly after) surgery may inhibit the adherence of Burkholderia cepacia complex to airways and may prevent or decrease subsequent infection of the allografts.

Bacterial Adhesion↗

PubMed2004

Vascular endothelial growth factor and related molecules in acute lung injury.

VEGFs and their receptors have been implicated in the regulation of vascular permeability in many organ systems, including the lung. Increased permeability and interstitial and pulmonary edema are prominent features of acute lung injury (ALI)/acute respiratory distress syndrome (ARDS). Extrapolating data from other organ systems and animal experiments have suggested that overexpression of VEGF functions primarily as proinjurious molecules in the lung. Recent data, from animal models as well as from patients with ARDS, have shown decreased levels of VEGF in the lung. The role of VEGF and related molecules in ALI/ARDS is, therefore, controversial: what has become clear is that there are many unique features in the regulation of pulmonary vascular permeability and in VEGF expression in the lung. In this review, we explore a growing body of literature looking at the expression and function of VEGF and related molecules in different models of ALI and in patients with ALI/ARDS. Novel evidence points to a potential role of VEGF in promoting repair of the alveolar-capillary membrane during recovery from ALI/ARDS. Understanding the role of VEGF in this disease process is crucial for developing new therapeutic strategies for ALI/ARDS.

Acute Disease↗

PubMed2003

Recipient T cells mediate reperfusion injury after lung transplantation in the rat.

Leukocytes have been implicated in ischemia-reperfusion (IR) injury of the lung, but the individual role of T cells has not been explored. Recent evidence in mice suggests that T cells may play a role in IR injury. Using a syngeneic (Lewis to Lewis) rat lung transplant model, we observed that recipient CD4(+) T cells infiltrated lung grafts within 1 h of reperfusion and up-regulated the expression of CD25 over the ensuing 12 h. Nude rats (rnu/rnu) and heterozygous rats (rnu/+) were used to determine the role of T cells in IR injury. No significant difference in lung function was observed between nude and heterozygous recipient rats after 2 h of reperfusion. However, after 12 h of reperfusion, recipient nude rats had significantly higher oxygenation and lower peak airway pressure than recipient heterozygous rats. This was associated with significantly lower levels of IFN-gamma in transplanted lung tissue of recipient nude rats. Reconstitution of recipient nude rats with T cells from heterozygous rats restored IR injury after 12 h of reperfusion. The effect of T cells was independent of neutrophil recruitment and activation in the transplanted lung. These results demonstrate that recipient T cells are activated and mediate IR injury during lung transplantation in rats.

Adoptive Transfer↗

PubMed2003

Directional sensing requires G beta gamma-mediated PAK1 and PIX alpha-dependent activation of Cdc42.

Efficient chemotaxis requires directional sensing and cell polarization. We describe a signaling mechanism involving G beta gamma, PAK-associated guanine nucleotide exchange factor (PIX alpha), Cdc42, and p21-activated kinase (PAK) 1. This pathway is utilized by chemoattractants to regulate directional sensing and directional migration of myeloid cells. Our results suggest that G beta gamma binds PAK1 and, via PAK-associated PIX alpha, activates Cdc42, which in turn activates PAK1. Thus, in this pathway, PAK1 is not only an effector for Cdc42, but it also functions as a scaffold protein required for Cdc42 activation. This G beta gamma-PAK1/PIX alpha/Cdc42 pathway is essential for the localization of F-actin formation to the leading edge, the exclusion of PTEN from the leading edge, directional sensing, and the persistent directional migration of chemotactic leukocytes. Although ligand-induced production of PIP(3) is not required for activation of this pathway, PIP(3) appears to localize the activation of Cdc42 by the pathway.

Actins↗

PubMed2003

Regulation of hematopoietic-specific G-protein Galpha15 and Galpha16 by protein kinase C.

Heterotrimeric G proteins mediate cell growth and differentiation by coupling cell surface receptors to intracellular effector enzymes. The G-protein alpha subunit, Galpha(16), and its murine homologue Galpha(15), are expressed specifically in hematopoietic cells and their expression is highly regulated during differentiation of normal and leukemic cells. In this study, we examined the phosphorylation of Galpha(15)/Galpha(16) and its role in receptor and effector coupling. We observed a PMA-stimulated intact cell phosphorylation of Galpha(15) in COS7 cells transfected with Galpha(15) and protein kinase Calpha (PKCalpha), and phosphorylation of endogenous Galpha(16) in HL60 cells. We also showed that peptides derived from the two G-proteins were phosphorylated in vitro using purified brain PKC. Furthermore, we identified the putative phosphorylation site and showed that mutation or deletion of this PKC phosphorylation site inhibited phospholipase C (PLC) activation. The behavior of double mutants with the constitutively active G-protein mutation (QL-mutant) and mutation in the putative phosphorylation site suggests that the phosphorylation site of Galpha(15/16) is essential for receptor-coupled activation of PLC, but not for direct interaction of the G-protein with PLC-beta.

Amino Acid Sequence↗

PubMed2003

Accommodation after lung xenografting from hamster to rat.

BACKGROUND: Long-term xenograft survival can be achieved in hamster hearts transplanted into rats treated with cobra venom factor (CVF) and cyclosporine A (CsA). This phenomenon of "accommodation" is associated with expression of protective genes such as bcl-2, bcl-X(L), and heme-oxygenase-1. We examined whether accommodation could be induced in hamster-to-rat lung xenografts and whether the pattern of protective genes is similar to cardiac xenografts. METHODS: We used hamster-to-rat cardiac and lung xenotransplantation models. Cardiac xenotransplants were treated with CVF+CsA and compared with untreated controls. Lung xenotransplants were treated with either CVF+CsA or FK506 and cyclophosphamide (Cp) and compared with untreated controls. All recipients were killed by 21 days after transplantation. We examined graft survival and protein expression of protective genes, and we performed histologic and immunohistologic analyses. RESULTS: Rejection occurred rapidly in untreated rats. CVF+CsA or FK506+Cp treatment significantly influenced graft survival. Eight of 12 CVF+CsA-treated heart transplants survived 21 days. Seven of 16 CVF+CsA-treated lung grafts and five of 12 FK506+Cp-treated lung xenografts survived 21 days. We observed significant protein expression of bcl-2, bcl-X(L), and heme-oxygenase-1 in cardiac xenografts treated with CVF+CsA at 2, 14, and 21 days after transplantation, compared with normal hamster hearts. We also observed significant expression of these proteins in lung xenografts treated with either CVF+CsA or FK506+Cp at 21 days after transplantation, compared with normal lungs. CONCLUSIONS: Accommodation may be a general phenomenon for all organs, mediated through protective genes. Induction of accommodation does not require disruption of the complement system.

Adaptation, Physiological↗

PubMed2003

Ischemia-reperfusion-induced lung injury.

Ischemia-reperfusion-induced lung injury is characterized by nonspecific alveolar damage, lung edema, and hypoxemia occurring within 72 hours after lung transplantation. The most severe form may lead to primary graft failure and remains a significant cause of morbidity and mortality after lung transplantation. Over the past decade, better understanding of the mechanisms of ischemia-reperfusion injury, improvements in the technique of lung preservation, and the development of a new preservation solution specifically for the lung have been associated with a reduction in the incidence of primary graft failure from approximately 30 to 15% or less. Several strategies have also been introduced into clinical practice for the prevention and treatment of ischemia-reperfusion-induced lung injury with various degrees of success. However, only three randomized, double-blinded, placebo-controlled trials on ischemia-reperfusion-induced lung injury have been reported in the literature. In the future, the development of new agents and their application in prospective clinical trials are to be expected to prevent the occurrence of this potentially devastating complication and to further improve the success of lung transplantation.

Graft Rejection↗

PubMed2003

A Rac/Cdc42-specific exchange factor, GEFT, induces cell proliferation, transformation, and migration.

The Rho family of small GTPases, including Rho, Rac, and Cdc42, play essential roles in diverse cellular functions. The ability of Rho family GTPases to participate in signaling events is determined by the ratio of inactive (GDP-bound) and active (GTP-bound) forms in the cell. The activation of Rho family proteins requires the exchange of bound GDP for GTP, a process catalyzed by the Dbl family of guanine nucleotide exchange factors (GEFs). The GEFs have high affinity for the guanine nucleotide-free state of the GTPases and are thought to promote GDP release by stabilizing an intermediate transition state. In this study, we have identified and characterized a new Rac/Cdc42-specific Dbl family guanine nucleotide exchange factor, named GEFT. GEFT is highly expressed in the excitable tissues, including brain, heart, and muscle. Low or very little expression was detected in other nonexcitable tissues. GEFT has specific exchange activity for Rac and Cdc42 in our in vitro GTPase exchange assays and glutathione S-transferase-PAK pull-down assays with GTP-bound Rac1 and Cdc42. Overexpression of GEFT leads to changes in cell morphology and actin cytoskeleton re-organization, including the formation of membrane microspikes, filopodia, and lamilliopodia. Furthermore, expression of GEFT in NIH3T3 cells promotes foci formation, cell proliferation, and cell migration, possibly through the activation of transcriptional factors involved in cell growth and proliferation. Together, our data suggest that GEFT is a Rac/Cdc42-specific GEF protein that regulates cell morphology, cell proliferation, and transformation.

Amino Acid Sequence↗

PubMed2003

Interleukin 10 gene transfection of donor lungs ameliorates posttransplant cell death by a switch from cellular necrosis to apoptosis.

BACKGROUND: We have previously shown that cell death is a pathophysiologic consequence of ischemia-reperfusion and that interleukin-10 gene therapy improves the function of transplanted lungs. Interleukin-10 downregulates the inflammatory response and can inhibit apoptosis. The objective was to determine whether donor lung transfection with the interleukin-10 gene ameliorates lung dysfunction by decreasing cell death after transplantation. METHODS: Single lung transplants were performed in 3 groups of rats (n = 5 each): AdhIL-10, transtracheal administration of Ad5E1RSVhIL-10 (5 x 10(9) pfu); EV, empty vector; and VD, vector diluent (3% sucrose). After in vivo transfection, donor lungs were excised, stored at 4 degrees C for 24 hours, and then transplanted. After 2 hours of reperfusion, lungs were flushed with trypan blue and fixed. TUNEL staining was used for the detection of apoptosis. This combined staining technique allows one to determine the mode of cell death by distinguishing apoptotic dead cells from necrotic dead cells. RESULTS: Lung function was superior in the interleukin-10 group (P =.0001) vs the EV and VD group (Pao(2): 240 +/- 31 mm Hg vs 98 +/- 17 mm Hg vs 129 +/- 11 mm Hg, respectively). Although the total number of dead cells (as percent of total cells) was similar in all groups (32.7% +/- 3.2%, 30.2% +/- 2.5%, and 30.3% +/- 3.8%), interestingly, apoptosis was highest in interleukin-10 lungs (9.7 +/- 1.9 vs 2 +/- 1.9 and 1.8 +/- 2, P =.0001), and necrosis was lowest in the interleukin-10 group (20.6 +/- 5.7 vs 28.3 +/- 3.1 and 30.3 +/- 4.2, P =.01). CONCLUSIONS: AdhIL-10 gene transfection improves function of transplanted lungs. Although the total number of cells dying as a result of the transplant process did not change, the mode of cell death appears to have been modified. It is possible that AdhIL-10, by decreasing proinflammatory cytokine production, ameliorates the overall injury and preserves the ability of damaged cells to undergo a more quiescent and less tissue-damaging mode of cell death-apoptosis, rather than necrosis.

Adenoviridae↗

PubMed2003

GGAPs, a new family of bifunctional GTP-binding and GTPase-activating proteins.

G proteins are molecular switches that control a wide variety of physiological functions, including neurotransmission, transcriptional activation, cell migration, cell growth. and proliferation. The ability of GTPases to participate in signaling events is determined by the ratio of GTP-bound to GDP-bound forms in the cell. All known GTPases exist in an inactive (GDP-bound) and an active (GTP-bound) conformation, which are catalyzed by guanine nucleotide exchange factors and GTPase-activating proteins (GAPs), respectively. In this study, we identified and characterized a new family of bifunctional GTP-binding and GTPase-activating proteins, named GGAP. GGAPs contain an N-terminal Ras homology domain, called the G domain, followed by a pleckstrin homology (PH) domain, a C-terminal GAP domain, and a tandem ankyrin (ANK) repeat domain. Expression analysis indicates that this new family of proteins has distinct cell localization, tissue distribution, and even message sizes. GTPase assays demonstrate that GGAPs have high GTPase activity through direct intramolecular interaction of the N-terminal G domain and the C-terminal GAP domain. In the absence of the GAP domain, the N-terminal G domain has very low activity, suggesting a new model of GGAP protein regulation via intramolecular interaction like the multidomain protein kinases. Overexpression of GGAPs leads to changes in cell morphology and activation of gene transcription.

ADP-Ribosylation Factors↗

PubMed2003

Impact of human interleukin-10 on vector-induced inflammation and early graft function in rat lung transplantation.

This study was undertaken to examine the time course of human interleukin (hIL)-10 gene expression after transtracheal administration of adenoviral (Ad)hIL-10 and its effect on the early adenoviral proinflammatory cytokine response and on post-transplant lung function. Using a rat lung transplant model, we observed that lungs retrieved 12 h after the administration of AdhIL-10 were associated with significant improvement in post-transplant lung function. Shorter periods of transfection were associated with significantly elevated levels of tumor necrosis factor-alpha and macrophage inflammatory protein-2 in lung tissue, leading to an increased degree of injury. The release of proinflammatory cytokines secondary to the adenoviral vector was reduced by high-dose methylprednisolone (30 mg/kg) administered 3 h before transfection. Reduction in the early adenoviral inflammatory response was associated with significant improvement in post-transplant lung function when lungs were retrieved 6 or 12 h after transtracheal administration of AdhIL-10. Transtracheal administration of adenoviral-mediated hIL-10 to donor lungs is associated with a significant early inflammatory response that may enhance ischemia-reperfusion injury if insufficient hIL-10 is expressed in lung tissue before retrieval. The period between delivery of AdhIL-10 and lung retrieval can be reduced if the early inflammatory response is suppressed with methylprednisolone.

Adenoviridae↗

PubMed2002

Expression of a novel member of sorting nexin gene family, SNX-L, in human liver development.

The sorting nexin (SNX) protein family is implicated in the regulation of receptor degradation and membrane traffic in the cell. With the aim of identifying novel genes involved in receptor degradation and recycling, we have cloned a new member of the sorting nexin gene family, human sorting nexin L, SNX-L (or SNX21). This gene includes 4 exons and 3 introns, and is located on chromosome 20q12-13.1 region, encompassing 8 kb. The full-length cDNA of SNX-L is 1,811 bp, with an open reading frame of 1,092 bp. The protein consists of 364 amino acids and encodes a 40 kDa protein. The SNX-L protein has a common PX domain shared by all SNX family members. The similarity of SNX-L PX domain to the PX consensus sequence is over 40%. PX domains have been shown to associate with specific phospholipids and membrane compartments. Expression analysis of SNX-L mRNA indicates that SNX-L is distinctly and highly expressed in fetus liver, but only weakly expressed in brain, muscle (skeleton muscle, smooth muscle, and cardiac muscle), kidney, and adrenal gland. Strong liver expression of SNX-L is maintained from 12 to 25 weeks during human fetus development, suggesting that SNX-L may be a regulatory gene involved in receptor protein degradation during embryonic liver development.

Amino Acid Sequence↗

PubMed2002

Expression of a novel Krüpple-like zinc-finger gene, ZNF382, in human heart.

With the aim of identifying genes involved in human heart development and disease, we have isolated a novel KRAB-related zinc-finger gene named ZNF382 from heart cDNA library. The ZNF382 gene has a predicted 548-amino acid open reading frame, encoding a putative 64kDa zinc-finger protein. The N-terminus of the ZNF382 coding region has a well-conserved Krüpple-associated box domain that consists of KRAB boxes A and B, whereas the C-terminus contains a Krüpple-type zinc-finger domain possessing nine C(2)H(2) zinc-finger motifs in tandem arrays. The ZNF382 gene is mapped to chromosome 19q13.13. Northern blot analysis indicates that a 2.9-kb transcript specific for ZNF382 is expressed at very early embryonic stage of human (at least earlier than gestation 34 day) and widely in human embryo tissues. At the adult stage, ZNF382 expression is restricted largely to heart tissue suggesting a potential role in heart development and function.

Amino Acid Sequence↗

PubMed2002

Curcumin-induced suppression of cell proliferation correlates with down-regulation of cyclin D1 expression and CDK4-mediated retinoblastoma protein phosphorylation.

Cyclin D1 is a proto-oncogene that is overexpressed in many cancers including breast and prostate. It plays a role in cell proliferation through activation of cyclin-dependent kinases. Curcumin, a diferuloylmethane, is a chemopreventive agent known to inhibit the proliferation of several breast and prostate cancer cell lines. It is possible that the effect of curcumin is mediated through the regulation of cyclin D1. In the present report we show that inhibition of the proliferation of various prostate, breast and squamous cell carcinoma cell lines by curcumin correlated with the down-regulation of the expression of cyclin D1 protein. In comparison, the down-regulation by curcumin of cyclin D2 and cyclin D3 was found only in selective cell lines. The suppression of cyclin D1 by curcumin led to inhibition of CDK4-mediated phosphorylation of retinoblastoma protein. We found that curcumin-induced down-regulation of cyclin D1 was inhibited by lactacystin, an inhibitor of 26S proteosome, suggesting that curcumin represses cyclin D1 expression by promoting proteolysis. We found that curcumin also down-regulated mRNA expression, thus suggesting transcriptional regulation. Curcumin also inhibited the activity of the cyclin D1 promoter-dependent reporter gene expression. Overall our results suggest that curcumin down-regulates cyclin D1 expression through activation of both transcriptional and post-transcriptional mechanisms, and this may contribute to the antiproliferative effects of curcumin against various cell types.

Acetylcysteine↗

PubMed2002

Identification and characterization of mouse metastasis-suppressor KiSS1 and its G-protein-coupled receptor.

G-protein-coupled receptors receive many different signals to activate different functions such as cellgrowth, proliferation, and migration. KiSS1 is a metastasis suppressor gene that has been shown to inhibit metastasis of human melanomas and breast carcinomas. The human KiSS1 gene encodes a COOH-terminally amidated active peptide, and this peptide is the ligand of a novel G-protein-coupled receptor. However, the mechanism of the antimetastatic actions of KiSS1 and its G-protein-coupled receptor has not been elucidated. In this study, we identified the mouse homologues of the KiSS1 peptide and its G-protein-coupled receptor and characterized the signaling pathways mediated by the activation of the KiSS1 receptor. Although human and mouse KiSS1 proteins share relatively low overall homology (52%), the active peptides (10-amino-acid residues) are highly conserved between mouse and human KiSS1 proteins, varying by only one conserved amino acid [Tyr (Y) to Phe (F)]. Activation of the receptor by KiSS1 peptide leads to the activation of G-protein-activated phospholipase C (PLC-beta), which suggests direct coupling of the KiSS1 peptide to the Galphaq-mediate PLC-Ca2+ signaling pathway. Furthermore, activation of the KiSS1 receptor inhibits cell proliferation and cell migration, key characteristics of tumor metastasis.

3T3 Cells↗

PubMed2002

A novel human SCAN/(Cys)2(His)2 zinc-finger transcription factor ZNF323 in early human embryonic development.

The C(2)H(2) zinc-finger motif found in many transcription factors is thought to be important for nucleic acid binding and/or dimerization. Here, we have identified and characterized a novel zinc-finger gene named ZNF323 using degenerate primers from an early human embryo heart cDNA library. The predicted protein contains six different C(2)H(2) type zinc fingers and a SCAN box. ZNF323 maps to chromosome 6p22.1-22.3. The expression levels were different during different development stages of human embryo between 15 and 23 weeks. Northern blot analysis shows that a 3.2-kb transcript specific for ZNF323 was expressed at high levels in the lung, liver, and kidney, while weakly expressed in intestine, brain, muscle, cholecyst, heart, and pancreas. In adult tissues, ZNF323 is expressed at high levels in liver and kidney, weakly in lung, pancreas, brain, placenta, muscle, and heart. Taken together, these results indicate that ZNF323 is a member of the zinc-finger transcription factor family and may be involved in the development of multiple embryonic organs.

Amino Acid Sequence↗