Bilateral retinal vascular occlusive disease in essential thrombocythemia.
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Diagnosis, Differential↗
Biomedical subjects
M Liu
Publications and source records attributed to M Liu.
Cell culture of sporadic hepatitis E virus in China.
The isolation and identification of the 87A strain of epidemic hepatitis E virus (HEV) by means of cell culturing have been described previously. This paper reports the successful isolation of a sporadic HEV strain (G93-2) in human lung carcinoma cell (A549) cultures. The etiology, molecular and biological properties, and serological relationship of this new strain to other, epidemic HEV strains are described. The propagation of both sporadic and epidemic HEV strains in a cell culture system will facilitate vaccine research.
Acids↗
beta-alanine and alpha-fluoro-beta-alanine concentrative transport in rat hepatocytes is mediated by GABA transporter GAT-2.
Studies on the compartmentalization of uridine catabolic metabolism in liver have indicated accumulation of beta-alanine as well as alpha-fluoro-beta-alanine (FbetaAL) for 5-fluorouracil in the hepatocytes. Using preparations of rat hepatocytes we were able to identify a Na+-dependent transport with high affinity for beta-alanine and GABA with Michaelis constant (Km) of 35.3 and 22.5 microM, respectively. A second Na+-dependent kinetic component with Km >1 mM was also identified. The sigmoidal profile of beta-alanine uptake with respect to Na+ shows the involvement of multiple ions of sodium in the transport process. A Hill coefficient of 2.6 +/- 0.4 indicates that at least two sodium ions are cotransported with beta-alanine. The flux of beta-alanine was also shown to be chlorine dependent. The substitution of this anion with gluconate, even in the presence of Na+, reduced the intracellular concentrative accumulation of beta-alanine to passive diffusion level, indicating that both Na+ and Cl- are essential for the activity of this transporter. The transport of beta-alanine was inhibited by GABA, hypotaurine, beta-aminoisobutyric acid, and FbetaAL in a competitive manner. However, concentrations up to 1 mM of L- and D-alanine, taurine, and alpha-aminoisobutyric acid did not affect beta-alanine uptake. Considering the similarities in substrate specificity with the rat GAT-2 transporter, extracts of hepatocytes were probed with the anti-GABA transporter antibody R-22. A 80-kDa band corresponding to GAT-2 was present in the hepatocyte and in the GAT-2 transfected Madin-Darby canine kidney cell extract, confirming the extraneural localization of this transporter. In view of these results, the neurotoxic effects related to the administration of uridine and 5-fluorouracil could be explained with the formation of beta-alanine and FbetaAL and their effect on the cellular reuptake of GABA.
Animals↗
Differential regulation of extracellular matrix molecules by mechanical strain of fetal lung cells.
We have previously shown that an intermittent mechanical strain regimen (5% elongation, 60 cycles/min, 15 min/h) that simulates fetal breathing movements stimulated fetal rat lung cell proliferation. Because normal lung growth requires proper coordination between cell proliferation and extracellular matrix (ECM) remodeling, we subjected organotypic cultures of fetal rat lung cells (day 19 of gestation, term = 22 days) to this strain regimen and examined alterations in ECM gene and protein expression. Northern analysis revealed that mechanical strain reduced messages for procollagen-alpha1(I) and biglycan and increased the levels of mRNA for collagen-alpha1(IV) and -alpha2(IV), whereas laminin beta-chain mRNA levels remained constant. Regardless of mRNA changes, mechanical strain increased the protein content of type I and type IV collagen as well as of biglycan in the medium. Mechanical strain did not affect gene expression of several matrix metalloproteinases (MMPs), such as MMP-1 (interstitial collagenase), MMP-2 (gelatinase A), and MMP-3 (stromelysin-1). Neither collagenase nor gelatinase (A and B) activities in conditioned medium were affected by mechanical strain. Tissue inhibitor of metalloproteinase activities in conditioned medium remained unchanged during the 48-h intermittent mechanical stretching. These data suggest that an intermittent mechanical strain differentially regulates gene and protein expression of ECM molecules in fetal lung cells. The observed increase in matrix accumulation appears to be mainly a result of an increased synthesis of ECM molecules and not of decreasing activity of degradative enzymes.
Animals↗
Mechanical strain-induced posttranscriptional regulation of fibronectin production in fetal lung cells.
We have shown that intermittent mechanical strain, simulating fetal breathing movements, stimulated fetal rat lung cell proliferation. Because normal lung growth requires proper coordination between cell proliferation and extracellular matrix remodeling, we investigated the effect of strain on fibronectin metabolism. Organotypic cultures of fetal rat lung cells, subjected to intermittent strain, showed increased fibronectin content in the culture media. Fibronectin-degrading activity in media from strained cells was similar to that of static cultures. Northern analysis revealed that strain inhibited fibronectin mRNA accumulation seen during static culture. Synthesis of fibronectin, determined by metabolic labeling, was increased by strain despite lower mRNA levels or presence of actinomycin D. This increase was not mediated via a rapamycin-sensitive mechanism. Strain stimulated prelabeled fibronectin secretion even in the presence of cycloheximide. These results suggest that strain differentially regulates fibronectin production of fetal lung cells at the transcriptional and posttranscriptional levels. Mechanical strain increases soluble fibronectin content by stimulating its synthesis and secretion without increasing fibronectin message levels.
Animals↗
LPS-induced depolymerization of cytoskeleton and its role in TNF-alpha production by rat pneumocytes.
Lipopolysaccharide (LPS) polymerizes microfilaments and microtubules in macrophages and monocytes. Disrupting microfilaments or microtubules with cytochalasin D (CytoD) or colchicine can suppress LPS-induced tumor necrosis factor-alpha (TNF-alpha) gene expression and protein production from these cells. We have recently demonstrated that primary cultured rat alveolar epithelial cells can produce TNF-alpha on LPS stimulation. In the present study, we found that the LPS-induced increase in TNF-alpha mRNA level and protein production in alveolar epithelial cells was not inhibited by CytoD or colchicine (1 nM to 10 microM). In fact, LPS-induced TNF-alpha production was further enhanced by CytoD (1-10 microM) and inhibited by jasplakinolide, a polymerizing agent for microfilaments. Immunofluorescent staining and confocal microscopy showed that LPS (10 microg/ml) depolymerized microfilaments and microtubules within 15 min, which was prolonged until 24 h for microfilaments. These results suggest that the effects of LPS on the cytoskeleton and the role of the cytoskeleton in mediating TNF-alpha production in alveolar epithelial cells are opposite to those in immune cells. This disparity may reflect the different roles between nonimmune and immune cells in host defense.
Actin Cytoskeleton↗
Mechanical force-induced signal transduction in lung cells.
The lung is a unique organ in that it is exposed to physical forces derived from breathing, blood flow, and surface tension throughout life. Over the past decade, significant progress has been made at the cellular and molecular levels regarding the mechanisms by which physical forces affect lung morphogenesis, function, and metabolism. With the use of newly developed devices, mechanical forces have been applied to a variety of lung cells including fetal lung cells, adult alveolar epithelial cells, fibroblasts, airway epithelial and smooth muscle cells, pulmonary endothelial and smooth muscle cells, and mesothelial cells. These studies have led to new insights into how cells sense mechanical stimulation, transmit signals intra- and intercellularly, and regulate gene expression at the transcriptional and posttranscriptional levels. These advances have significantly increased our understanding of the process of mechanotransduction in lung cells. Further investigation in this exciting research field will facilitate our understanding of pulmonary physiology and pathophysiology at the cellular and molecular levels.
Animals↗
Upregulation of T-helper 1 cytokines and chemokine expression in post-transplant airway obliteration.
The major obstacle to long-term survival after lung transplantation is chronic graft dysfunction manifest as bronchiolitis obliterans. Since the early stages are characterized by proliferation of itinerant cells (lymphocytes and macrophages), we hypothesized that cytokines and chemokines may play a role in the development of the fibroproliferative process. In a heterotopic rat tracheal transplant model, we studied isografts and allografts 3, 7, and 21 d after transplantation as representative time points for the triphasic time course in the evolution of allograft airway obliteration. Using a semiquantitative RT-PCR technique, intragraft gene expression of T-helper 1 (Th1)- and Th2-type cytokines and of C-C and C-X-C chemokines was examined. The results of our study show a distinct pattern of cytokine and chemokine gene expression in the development of post-transplant airway obliteration. Allografts, in contrast to isografts, showed a strong and persistent Th1-type response (expression of interleukin-2 and interferon-gamma genes), even after fibrous airway obliteration was complete, suggesting an ongoing allo-immune process until late in the fibroproliferative stage. RANTES and MCP-1 were also upregulated late after transplantation, whereas MIP-2 upregulation occurred early post-transplant and was not restricted to allografts alone, which might reflect alloantigen-independent processes after transplantation that are present in both allografts and isografts.
Animals↗
Effect of adrenoreceptors on endotoxin-induced cytokines and lipid peroxidation in lung explants.
Lung tissue may be an important source of systemic inflammation associated with sepsis and the acute respiratory distress syndrome (ARDS). An ex vivo model of freshly explanted lung tissue in culture was developed to evaluate the ability of lipopolysaccharide (LPS) to directly stimulate lung tissues under conditions where indirect mechanisms such as recruitment of blood-derived inflammatory cells could not be implicated. Under control conditions, lung explants produced a high level of macrophage inflammatory protein-2 (MIP-2). Eight hours after LPS challenge, there were marked increases in the production of tumor necrosis factor-alpha (TNF-alpha) from 0.18 +/- 0.04 to 4.13 +/- 0.23 ng/ml/g tissue (p < 0.05), MIP-2 from 60.0 +/- 7.4 to 165.6 +/- 10.3 ng/ml/g tissue (p < 0.05), and tissue lipid peroxidation (malonaldehyde from 27.6 +/- 2.5 to 48.4 +/- 17.5 microM/g tissue; and 4-hydroxyalkenal from 34.0 +/- 3.0 to 59.7 +/- 18.8 microM/g tissue, both p < 0.05) from lung explants. Treatment with the beta-adrenoreceptor agonist isoproterenol (1 ng/ml) attenuated LPS-induced release of TNF-alpha and lipid peroxidation in association with an increase in intracellular cAMP levels. The adenylate cyclase activator, forskolin, also inhibited LPS-induced changes in TNF-alpha and lipid peroxidation. In conclusion, increasing intracellular levels of cAMP through beta-adrenoreceptor activation can attenuate the acute inflammatory response induced in the lung by LPS. LPS did not significantly impair the beta-adrenoreceptor reactivity in lung explants. Lung explants allow for the quantitative assessment of pulmonary inflammatory responses independent of influences from the circulation, and thus may be a useful ex vivo model to investigate cellular and molecular mechanisms of lung injury.
Adenylyl Cyclases↗
Tumor necrosis factor-alpha mediates lipopolysaccharide-induced macrophage inflammatory protein-2 release from alveolar epithelial cells. Autoregulation in host defense.
Our recent studies have demonstrated that in response to lipopolysaccharide (LPS) challenge, alveolar epithelial cells produced tumor necrosis factor (TNF)-alpha, an early response cytokine in the inflammatory process. To investigate whether LPS-induced TNF-alpha release is related to other inflammatory mediators from the same cell type, we examined effects of LPS stimulation on macrophage inflammatory protein (MIP)-2 production by alveolar epithelial cells, and then examined the relationship between TNF-alpha and MIP-2 production. LPS stimulation induced a dose- and time-dependent release of MIP-2. The steady-state messenger RNA level of MIP-2 was significantly increased, with the MIP-2 protein localized within alveolar epithelial cells, as determined by confocal microscopy. The LPS-induced MIP-2 production is regulated at both the transcriptional and post-transcriptional levels. TNF-alpha also induced MIP-2 production from alveolar epithelial cells. Preincubation with an antisense oligonucleotide against TNF-alpha inhibited LPS-induced TNF-alpha in a dose-dependent and sequence-specific manner. The same antisense also inhibited MIP-2 production. The inhibitory effects were highly correlated. Polyclonal and monoclonal antibodies against TNF-alpha also attenuated LPS-induced MIP-2. These results suggest that LPS-induced MIP-2 release from alveolar epithelial cells may be mediated in part by TNF-alpha from the same cell type. This autoregulatory mechanism may amplify LPS-induced signals involved in host defense as well as in acute inflammatory reactions.
Animals↗
Androgen regulation of the cyclin-dependent kinase inhibitor p21 gene through an androgen response element in the proximal promoter.
Androgen is essential for the physiological maintenance of the integrity of prostatic epithelial cells, and castration causes the cells to undergo apoptosis. To study the molecular mechanism of androgen-dependent cell growth, we showed that androgen up-regulates the expression of the cyclin-dependent kinase inhibitor p21 (WAF1, CIP1, SDI1, CAP20) gene at both the mRNA and protein levels. Nuclear run-on assays demonstrated that androgen stimulates endogenous p21 gene expression at the transcriptional level. Transient transfection experiments showed that androgen can enhance the activity of a 2.4-kb promoter of the p21 gene linked to a luciferase reporter. These results suggested that a putative androgen response element (ARE), which mediates androgen response to enhance the p21 transcription, is included in the 2.4-kb promoter fragment. Deletion analysis of the promoter revealed a functional ARE (AGCACGCGAGGTTCC) located at -200 bp of the p21 gene proximal to the promoter region. Electrophoretic mobility shift assay further demonstrated that the androgen receptor specifically binds to this element. Wild-type ARE, but not mutant ARE, confers androgen responsiveness to a heterologous promoter. The up-regulation of p21 gene expression by androgen suggests that p21 may have an antiapoptotic function in prostatic epithelial cells. However, this hypothesis will need to be tested in future experiments.
Androgens↗
99th general meeting of the American Society for Microbiology. May 30 - June 3 1999, Chicago, Illinois, USA.
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Journal Article↗
Developmental alterations in the alpha-fetoprotein sugar chain in maternal serum analyzed by lectin affinity electrophoresis.
Our purpose was to investigate developmental alterations of human alpha-fetoprotein (AFP) oligosaccharides in maternal serum by lectin affinity electrophoresis and to compare the AFP glycoforms in maternal serum with those in umbilical cord serum and amniotic fluid. AFP glycoforms were separated by affinity electrophoresis with concanavalin A (Con A), lentil lectin (LCA), erythroagglutinating phytohemagglutinin (E-PHA) and Allomyrina dichotoma lectin (allo A) and detected by sensitive antibody affinity blotting. In maternal serum, increased proportions of Con A-nonreactive AFP (AFP-C1), LCA strongly-reactive AFP (AFP-L3) and E-PHA-reactive AFP (AFP-P4 and AFP-P5) decreased gradually during the early gestational weeks. Allo A-nonreactive AFP (AFP-A1 and asialo-AFP) were found only in amniotic fluids during early gestational weeks. The percentages of these glycoforms at full term were almost the same among those body fluids. Since the glycoforms of maternal serum AFP were close to those of umbilical cord serum AFP, lectin-affinity electrophoretic analysis of maternal serum AFP may be useful for evaluating the developmental state of fetus by examining the nature of AFP sugar chain.
Amniotic Fluid↗
Mitral valve replacement with complete mitral leaflet retention: operative techniques.
BACKGROUND AND AIMS OF THE STUDY: This report describes surgical indication and operative technique of complete preservation of the mitral valvular and subvalvular apparatus during mitral valve replacement. METHODS: Twenty patients, 12 with rheumatic lesions and eight with congenital lesions, were operated between 1991 and 1996. The left atrium was opened using a trans-septal approach through the right atrium in 17 patients, and at the intra-atrial groove in three. The valve was sized without excising any mitral valvular or subvalvular tissue. Teflon pledget-reinforced horizontal mattress valve sutures were passed from the left atrium, through the mitral annulus, around the free edge of mitral leaflet, and up through the prosthetic sewing ring. The prosthetic valve was seated and the sutures tied, reefing the native leaflets and compressing them between the sewing ring and native annulus. Thus, chordal tension on the ventricle was evenly maintained. RESULTS: There was no operative or late death. Postoperative results were excellent. Echocardiography showed that none of the patients had any observable anterior leaflet and redundant subvalvular tissue in the left ventricular outflow tract (LVOT); thus, neither LVOT obstruction nor interference with prosthetic valve function occurred. CONCLUSIONS: Based on these findings, it is suggested that when mitral valve replacement is required in patients with mitral insufficiency (MI) or MI with mild stenosis, the mitral valvular and subvalvular tissue should be completely preserved.
Adult↗
Effects of alcohol use and gender on the dynamics of EKG time-series data.
Hurst analysis of EKG data obtained from a population of alcoholic (n = 13) and nonalcoholic (n = 48) subjects was undertaken. Potential subjects (n = 120) were screened using the Schedule for Affective Disorders and Schizophrenia and Structured Clinical Interview for DSM-III instruments. Data from subjects with a diagnosis of current alcohol dependence were analyzed. Subjects with diagnoses such as major depression, bipolar disorder or schizophrenia (Axis I diagnoses), or personality disorders (Axis II diagnoses) were excluded from analysis. Subjects undergoing testing were free of alcohol and illicit drugs. Alcoholic subjects had no clinical evidence of alcohol withdrawal symptoms at the time of testing. EKG data were obtained with eyes open or with eyes closed. Approximately 3.5 min of data were obtained for each condition. Alcoholic subjects had less complex heart rate dynamics as evidenced by higher values of H = 0.18 +/- 0.05 (mean +/- SEM), compared with healthy comparison subjects with H = 0.09 +/- 0.02, p < 0.014 for the eyes closed condition, and H = 0.17 +/- 0.05 (mean +/- SEM) compared with healthy comparison subjects with H = 0.07 +/- 0.02,p < 0.011 for the eyes open condition. A gender effect was seen, with female subjects showing evidence of more complex heart rate dynamics than male subjects.
Alcohol Drinking↗
[An investigation of the polymorphism of HLA class II alleles in the Han population in Hubei Province of China].
OBJECTIVE: To investigate the polymorphism of HLA class II alleles in the Han population in Hubei province. METHODS: The alleles of DRB1*(n=168), DQB1*(n=160) and DPB1*(n=93) were typed by using the polymerase chain reaction/sequence specific primer(PCR/SSP) and polymerase chain reaction/restriction fragment length polymorphism (PCR/RFLP) techniques. RESULTS: 39 HLA-DRB1, 15 DQB1 and 17 DPB1 alleles were found. Alleles with higher frequencies are DRB1*0901 (GF=14%), *1501(GF=11.3%), *0301(GF=7.1%), *0803(GF=4.8%); DQB1*0301(GF=18.8%), *0303(GF=18.4%), *0201(GF=10%), *0302(GF=8.4%); DPB1*0501(GF=31.2%), *0401(GF=15.1%), *0201(GF=14%), *0402(GF=11.8%), respectively. As compared with Caucasians, the Han people in Hubei province have higher gene frequencies of DRB1*0901, *1001, *0803; DQB1*0303, *0502 and DPB1*0501, *0202; and lower gene frequencies of DRB1*0301, *0401, *1301; DQB1*0201, *0603 and DPB1*0401, suggesting that Hubei Hans have their own layout of HLA class II allele frequencies. CONCLUSION: These data may serve as normal reference values for the Han population in south China.
Alleles↗
[Scanning electron microscope observation on endosperm starch grain characters in multiplasmic maize].
In this article, endosperm starch grains of eleven lines in multiplasmic maize were studied by scanning electron microscope. The results show that different cytoplasm has different effects on the characters of starch grain. The starch grains of three sweet corn cytoplasmic lines (su1, sh2, btl) are mainly spherical and packed tightly, which means they have some degree of similarity. While the grains of four cytolasmic male sterility lines (T, S, C, 21A) are mostly irregular and packed loosely except (T) Mo17, in which grains are tightly packed. The average diameter of these eleven varieties is ranged from 9.78 microns to 14.69 microns. Through the study of endosperm starch grain shape and size, we tried to explore the relationship between the property of starches and the quality of seeds. And this will significantly prompt the development of maize genetics and breeding.
Fertility↗
Prognostic factors in squamous cell carcinomas of the head and neck.
This review will focus on prognostic factors that can be disclosed by the pathological and molecular analysis of squamous cell carcinomas of the head and neck. The following pathological prognostic factors are considered and discussed: location, histopathology, lymph node metastasis. In addition, a number of molecular genetic markers have been identified such as: DNA content, chromosomal abnormalities, cell proliferation, RAS gene family, epidermal growth factor and its receptor, tumor-suppressor genes, cell adhesion molecules and proteinases.
Biomarkers, Tumor↗