Biomedical subjects

Gang Liu

Publications and source records attributed to Gang Liu.

At least 199 records · Page 11Linked to original sources

PubMed2003

Gene expression in lung adenocarcinomas of smokers and nonsmokers.

Adenocarcinoma (AC) has become the most frequent type of lung cancer in men and women, and is the major form of lung cancer in nonsmokers. Our goal in this paper was to determine if AC in smokers and nonsmokers represents the same genetic disease. We compared gene expression profiles in resected samples of nonmalignant lung tissue and tumor tissue in six never-smokers with AC and in six smokers with AC, who were matched for clinical staging and histologic criteria of cell differentiation. Results were analyzed using a variety of bioinformatic tools. Four times as many genes changed expression in the transition from noninvolved lung to tumor in nonsmokers as in smokers, suggesting that AC in nonsmokers evolves locally, whereas AC in smokers evolves in a field of genetically altered tissue. There were some similarities in gene expression in smokers and nonsmokers, but many differences, suggesting different pathways of cell transformation and tumor formation. Gene expression in the noninvolved lungs of smokers differed from that of nonsmokers, and multidimensional scaling showed that noninvolved lungs of smokers groups with tumors rather than noninvolved lungs of nonsmokers. In addition, expression of a number of genes correlated with smoking intensity. Our findings, although limited by small sample size, suggest that additional studies comparing noninvolved to tumor tissue may identify pathogenetic mechanisms and therapeutic targets that differ in AC of smokers and nonsmokers.

Adenocarcinoma↗

PubMed2003

Coverage effects and the nature of the metal-sulfur bond in S/Au(111): high-resolution photoemission and density-functional studies.

The bonding of sulfur to surfaces of gold is an important subject in several areas of chemistry, physics, and materials science. Synchrotron-based high-resolution photoemission and first-principles density-functional (DF) slab calculations were used to study the interaction of sulfur with a well-defined Au(111) surface and polycrystalline gold. Our experimental and theoretical results show a complex behavior for the sulfur/Au(111) interface as a function of coverage and temperature. At small sulfur coverages, the adsorption of S on fcc hollow sites of the gold substrate is energetically more favorable than adsorption on bridge or a-top sites. Under these conditions, S behaves as a weak electron acceptor but substantially reduces the density-of-states that gold exhibits near the Fermi edge. As the sulfur coverage increases, there is a weakening of the Au-S bonds (with a simultaneous reduction in the Au --> S charge transfer and a modification in the S sp hybridization) that facilitates changes in adsorption site and eventually leads to S-S bonding. At sulfur coverages above 0.4 ML, S(2) and not atomic S is the more stable species on the gold surface. Formation of S(n)(n > 2) species occurs at sulfur coverages higher than a monolayer. Very similar trends were observed for the adsorption of sulfur on polycrystalline surfaces of gold. The S atoms bonded to Au(111) display a unique mobility/reactivity not seen on surfaces of early or late transition metals.

Journal Article↗

PubMed2003

Lysozyme: a mediator of myocardial depression and adrenergic dysfunction in septic shock in dogs.

The objective of the present study was to identify the nature of a filterable cardiodepressant substance (FCS) that contributes to myocardial dysfunction in a canine model of Escherichia coli septic shock. In a previous study, it was found that FCS increased in plasma after 4 h of bacteremia (Am J Physiol 1993;264:H1402) in which FCS was identified by a bioassay that included a right ventricular trabecular (RVT) preparation. In that study, FCS was only partially identified by pore filtration techniques and was found to be a protein of molecular weight between 10 and 30 K. In the present study, FCS was further purified by size exclusion high-pressure liquid chromatography, until a single band was identified on one-dimensional gel electrophoresis. This band was then subjected to tandem mass spectrometry and protein-sequencing techniques and both techniques identified FCS as lysozyme c (Lzm-S), consistent with that originating from the canine spleen. Confirmatory tests showed that purified Lzm-S produced myocardial depression in the RVT preparation at concentrations achieved during sepsis in the in vivo preparation. In addition, Lzm-S inhibited the adrenergic response induced by field stimulation and the beta- agonist isoproterenol in in vitro preparations, these results suggesting that Lzm-S may inhibit the sympathetic response in sepsis. The present findings indicate that Lzm-S originating from disintegrating leukocytes from organs such as the spleen contributes to myocardial dysfunction in this model. The mechanism may relate to its binding or hydrolysis of a cardiac membrane glycoprotein thereby interfering with myocardial excitation-contraction coupling in sepsis.

Adrenergic Antagonists↗

PubMed2003

Disruption of sabR affects nikkomycin biosynthesis and morphogenesis in Streptomyces ansochromogenes.

The gene, sabR, encoding a receptor for gamma-butyrolactone, was cloned from the genomic DNA of Streptomyces ansochromogenes 7100. Its deduced protein shows strong homology to several gamma-butyrolactone-binding proteins in Streptomyces. Disruption of sabR retarded nikkomycin production in liquid media containing glucose or glycerol as carbon source. Sporulation of sabR disruption mutants was earlier than the parent strain on solid media with glucose or glycerol as carbon source. However, disruption of sabR had no effect on either nikkomycin production or sporulation on media containing mannitol as carbon source, suggesting that sabR is a pleiotropic regulatory gene that controls the onset of nikkomycin production and sporulation in S. ansochromogenes and is related to the utilization of carbon source.

4-Butyrolactone↗

PubMed2003

Neph1 and nephrin interaction in the slit diaphragm is an important determinant of glomerular permeability.

Neph1-deficient mice develop nephrotic syndrome at birth, indicating the importance of this protein in the development of a normal glomerular filtration barrier. While the precise subcellular localization of Neph1 remains unknown, its relationship with other components of the glomerular filtration barrier is of great interest in this field. In this paper, we localize the expression of Neph1 to the glomerular slit diaphragm by immunogold electron microscopy in rodents and describe its direct interaction with two other components of the slit diaphragm, nephrin and ZO-1. Both native and recombinant Neph1 associate with each other as dimers and multimers and interact with nephrin via their extracellular segments. Disruption of the Neph1-nephrin interaction in vivo by injecting combinations of individual subnephritogenic doses of anti-Neph1 and anti-nephrin results in complement- and leukocyte-independent proteinuria with preserved foot processes. This disruption modestly reduces Neph1 and nephrin protein expression in podocytes and dramatically reduces ZO-1 protein expression via the interaction of ZO-1 PDZ domains with the cytoplasmic tail of Neph1, independent of changes in mRNA expression of all three genes. The interaction between nephrin and Neph1 is specific and not shared by either protein with P-cadherin, another integral slit diaphragm protein. The interaction between nephrin and Neph1 therefore appears to be an important determinant of glomerular permeability.

Amino Acid Sequence↗

PubMed2003

Metabolic Diseases Drug Discovery World Summit.

This year's Metabolic Diseases Drug Discovery World Summit, consisting of a gathering of mostly researchers from pharmaceutical and biotech industry, was held in picturesque San Diego. The diverse programme covered recent advances in drug discovery and development for the treatment of type II diabetes, metabolic syndrome and obesity. The ranges of topics included basic physiology, therapeutic target identification/validation, lead development/optimisation, profiling of development candidates and update on clinical trials. This report will attempt to highlight some of the important developments presented at this symposium.

Animals↗

PubMed2003

Protein tyrosine phosphatase 1B inhibition: opportunities and challenges.

Protein tyrosine phosphatase 1B (PTP1B) has been implicated as one of the key negative regulators of insulin and leptin signal transduction pathways. PTP1B deficient mice are more sensitive to insulin, and have improved glycemic control and resistance to diet-induced obesity than the wild-type control mice. Inhibiting PTP1B action using antisense oligonucleotides and small molecule inhibitors represents novel therapeutic approach for the treatment of insulin resistance, type II diabetes, and obesity. The rapid development of this field is evidenced by the increasing number of patents and publications in recent years. This review will highlight the recent advances in various approaches for attenuating PTP1B action, particularly small molecule PTP1B inhibitors, and the challenges associated with developing PTP1B inhibitors with drug like properties.

Acetates↗

PubMed2003

[Cloning of cDNA of TSARG4, a human spermatogenesis related gene].

To understand molecular mechanism of spermatogenesis, two ESTs BG720564 and AI700454, were found from SPAG4 (sperm antigen 4), a gene related to dense fiber protein of outer membrane of the human sperm and mouse spermatocytes gene AK006225. The gap was filled by polymerase chain reaction, and a 1252 bp fragment was obtained. This 1252 bp fragment was named TSARG4 (testis and spermatogenesis related gene 4 (GenBank accession number AF401350). Its opening reading frame was 94-1233 bp, as was proved by RT-PCR in human testis. TSARG4 gene was located in 20q11.2, and the putative protein was 379 amino acid with a theoretical molecular weight of 43 081 and isoelectric point of 8.61. The homologies of amino acid sequences were 74% between TSARG4 and AK006225 gene and 45% between TSARG4 and SPAG4 gene, respectively. The human TSARG4 mRNA is expressed in a wide range of adult tissues, including testis, whereas the homologous mouse spermatocytes gene AK006225 is expressed specifically in the testis.

Amino Acid Sequence↗

PubMed2003

[Effect of human bone marrow mesenchymal stem cell on cord blood T lymphocyte transformation].

To study the effect of mesenchymal stem cell (MSC) on immune function, MSCs were isolated and cultured from human bone marrow cells. The purity of MSCs were identified with the spindle-fibroblastic morphology characterization by microphotograph and the phenotypes were tested by flow cytometry. MSCs were plated in 96-well plates (2,000/well and 1,000/well), and cocultured for 3 days with T cells isolated from cord blood. Cord blood T cells non-cocultured with MSC acted as control group. After cord blood T cells stimulated by PHA for 60 hours, [(3)H]-thymidine was added to each well and T cell proliferation was assessed by [(3)H] thymidine incorporation. The results showed that cord blood T cell proliferation was suppressed when 2,000 MSCs were plated each well and cord blood T cell proliferation was activated when 1,000 MSCs were plated. Our results suggested that the immunomodulatory function of MSC seemed dependent on cell dose. High concentration of MSC most often resulted in inhibition, while low concentration resulted in stimulation.

Antigens, CD↗

PubMed2003

[Molecular cloning of TSARG3 gene related to apoptosis in human spermatogenic cells].

OBJECTIVE: To clone a novel gene which is related to human testis spermatogenesis apoptosis. METHODS: To rapidly attain human novel gene full-length cDNA sequence from a human testis cDNA library,the gene-specific primers and the vector-specific primers were designed for nested polymerase chain reaction. Sequencing was performed and the result was analysed. RESULTS: The present authors discovered the TSARG3 gene(GenBank accession number AF419291) from a human testis cDNA library, using a cDNA fragment (GenBank accession number BE644537) as an electronic probe, which was significantly changed in cryptorchidism and represented a novel gene. Furthermore, a mouse homologue of this gene was identified (GenBank accession number AF419292) by using the same method. CONCLUSION: A novel gene named TSARG3 was cloned. It is considered that the function of the new gene is related to human testis spermatogenesis apoptosis.

Amino Acid Sequence↗

PubMed2003

[Peripheral blood mutated p53 DNA and its clinical value in human breast cancer].

OBJECTIVE: To evaluate the clinical value of mutated p53 in the peripheral blood of breast cancer patients. METHODS: Plasma DNA of 126 breast cancer patients and 92 healthy women was examined. DNA extraction from the tumor and tissue samples was performed by a nonorganic method. Plasma DNA was purified on Qiagen columns. PCR-SSCP analysis was performed to examine the point mutations in the conserved exons 5, 6, 7 and 8 of TP53. RESULTS: The mean concentration of plasma DNA was 21 ng/ml in healthy women and 211 ng/ml in patients with breast cancer (P < 0.01). p53 mutations in the primary tumor were detected in 46 of 126 (36.5%) breast cancer patients. Of these 46 patients, 30 (65.1%) were also found to have p53 mutations in their plasma DNA. p53 mutation in plasma DNA was closely correlated with clinical stage, tumor size, lymph node (LN) metastasis and estrogen receptor status (P < 0.05). Survival of the patients with both primary tumor and plasma p53 mutations was the worst. Thirteen of the 22 (59.0%) patients with recurrence and/or metastasis had detectable p53 mutations in their plasma DNA. CONCLUSION: p53 mutations in plasma DNA may be a useful prognostic factor and an early marker of recurrence or distant metastasis in breast cancer.

Adult↗

PubMed2003

[Molecular cloning for testis spermatogenesis cell apoptosis related gene TSARG1 and Mtsarg1 and expression analysis for Mtsarg1 gene].

Spermatogenesis cell apoptosis is a very complex process, which needs many molecules to take part in the programmable death of cells in testis. At present, research of apoptosis for spermatogenesis cell is at the primary step. It is very important to clone spermatogenesis cell apoptosis related genes and spermatogenesis genes in testis. Applying the bioinformatics and experiment technique, we have cloned human and mouse novel gene cDNA sequences--human testis and spermatogenesis cell apoptosis related gene 1 (TSARG1) and mouse testis and spermatogenesis cell apoptosis related gene 1(Mtsarg1) from human and mouse testis cDNA library respectively, using a cDNA fragment (GenBank accession number: BE644538) as an electronic probe, which was significantly changed in expression in cryptorchidism. The GeneBank accession numbers of Mtsarg1 and TSARG1 are AF399971 and AY032925 (NM_139073), respectively. The Mtsarg1 has a 55% identity and 61% similarity with TSARG1 at the amino acid level, which did not share significant homology with any other known protein in databases. The full-length cDNA of TSARG1 gene is 973 bp, including 549 bp open reading frame(ORF) and coding 183 amino acids, whereas the full-length cDNA of Mtsarg1 gene is 1103 bp, including 576 bp ORF and coding 192 amino acids. The predicted molecule weight of TSARG1 is 19948.61 Dolton, and the deduced iso-electric point is 10.24, whereas the Mtsarg1 is 20875.93 and is 9.83, being alkaline proteins. RT-PCR analysis showed that Mtsarg1 was expressed significantly in testis and faintly in epididymis in the ten tissues of testis, ovary, spleen, kidney, lung, heart, brain, epididymis, liver and skeletal muscle in mouse, while it wasn't expressed in the other eight tissues. Therefore, our results suggested that Mtsarg1 and TSARG1 would be pay potential roles in spermatogenesis cell apoptosis or spermatogenesis.

Amino Acid Sequence↗

PubMed2003

Expression research for human DDX36 and mouse Ddx36 gene in the adult testis.

Drosophila melanogaster is one of the most intensively studied organisms in biology and serves as a model system for structural and functional genomic research. With the strategy of homologue molecular cloning using the sequence of the maleless gene (mle) of Drosophila, the novel homologous human and mouse genes with longer DNA/RNA helicase box (DEAD/DEAH box), named, DDX36 and Ddx36 genes, respectively, were cloned as new members of the DEAD/H box superfamily. In order to further investigate the relationship between those two genes of DDX36 and Ddx36 and the role of spermatogenesis, the expression analysis of them have been performed by the techniques of Northern blotting, RT-PCR and tissue in situ hybridization. The result indicated that the DDX36 and Ddx36 gene has highly expressed in the adult testis. It was primarily suggested that DDX36 and Ddx36 gene may be related with spermatogenesis.

Adult↗

PubMed2003

[Effects of free air CO2 enrichment on rice canopy energy balance].

The change of crop canopy energy balance will affect crop growth and development and its water use efficiency. In this study, the FACE system (setup at at Anzhen, Wuxi, Jiangsu Province in 2001) was used to investigate the effects of FACE on rice canopy energy balance. The rice canopy microclimate observations were carried out from August 26 to October 13, 2001 when the rice crops were at the heading to maturing stage. The results showed that the maximum difference of rice canopy sensible and latent heat fluxes between ambient and FACE occurred at the same time of minimum air humidity, i.e., at about 14:00. From flowering to maturing stage, the maximum difference of rice canopy sensible and latent heat flux between FACE and ambient varied between 12-55 J.m-2.s-1 and -15(-)-65 J.m-2.s-1, respectively. The daytime total canopy sensible and latent heat fluxes of FACE were higher and lower than those of ambient, respectively, throughout flowering to maturing stage. The differences of daytime total canopy sensible and latent heat fluxes between ambient and FACE increased with the increase of net radiation above canopy during the same development stage, but decreased with the progress of the development stage. From flowering to maturing stage, the average difference of daytime total canopy latent heat flux between ambient and FACE was about 6.7%. FACE increased and decreased the ratio of daytime total canopy sensible and latent heat flux to daytime total net radiation above canopy, respectively, the ratio differences between FACE and ambient were 5.5%.

Air↗

PubMed2003

[Identification of Puumala like viruses in China].

BACKGROUND: To confirm if Puumala like viruses exist in China. METHODS: RNA was extracted from lungs of bank voles captured in the Northeast China, partial S segments genome of Puumala viruses were amplified and sequenced. RESULTS: 926 bp cDNA of S segments of Puumala like virus was amplified and sequenced. The phylogenetic analysis revealed that the Puumala like viruses found in China were most close to that found in Far East region of Russia. CONCLUSIONS: Puumala like virus does exist in Northeast China, and the nucleotides sequence of the viruses have high homolog to Puumala viruses found in Russia.

Animals↗

PubMed2003

[Relation of resting energy expenditure to respiratory mechanics and arterial blood gases in chronic obstructive pulmonary disease patients].

OBJECTIVE: To investigate the relationships of the rest energy expenditure to the respiratory mechanics and arterial blood gases in chronic obstructive pulmonary disease (COPD) patients. METHODS: Twenty six patients with COPD and 21 healthy subjects were involved in the study. The rest energy expenditure (REE), oxygen consumption (VO(2)), carbon dioxide production (VCO(2)) and respiratory quotient (RQ) were measured with indirect energy measurements of canopy test; the arterial blood gases were measured soon after energy measurements; then routine pulmonary function, P(0.1) and P(IMAX) were measured at rest. RESULTS: (1) The REE/day, P(0.1)/P(IMAX) and heart rate (HR) in the COPD group [(1,577.69 +/- 311.31) kcal, 0.068 +/- 0.026 and (83.46 +/- 11.36) BPM, respectively] were significantly higher than those in the healthy control group [(1,388.29 +/- 194.89) kcal, 0.039 +/- 0.014 and (69.71 +/- 5.73) BPM, respectively, P < 0.05 for all]; the forced expiratory volume in one second (FEV(1))% of predicted, partial pressure of oxygen in artery (PaO(2)) and arterial oxygen saturation (SaO(2)) in the COPD group [(50.46 +/- 21.35)%, (77.72 +/- 8.84) mm Hg and (92.54 +/- 2.55)%, respectively] were significantly lower than those in the control group [(92.29 +/- 11.91)%, (92.50 +/- 3.82) mm Hg and (96.29 +/- 1.87)%, respectively, P < 0.01 for all]. (2) In COPD group, the REE/day was positively correlated with body height, body weight, body mass index, P(0.1)/P(IMAX) and HR (r = 0.57, 0.65, 0.62, 0.41 and 0.51, respectively, P < 0.05 for all), negatively correlated with FEV(1)%, PaO(2) and SaO(2) (r = -0.43, -0.47 and -0.32, respectively, P < 0.05 for all); the P(0.1) was negatively correlated with PaO(2) and SaO(2) (r = -0.62 and -0.53, respectively, P < 0.01). CONCLUSION: The rest energy expenditure of COPD patients was significantly higher than that of healthy subjects. This increase in REE was not only attributed to the airway obstruction and the damaged gas exchange, but may be related to the elevated respiratory drive and dysfunction of respiratory muscles as well.

Aged↗

PubMed2003

[Ex vivo expansion of CD34+ cells from human umbilical cord blood by FL gene transfected bone marrow stromal cells].

The object of this study was to explore the effect of FL gene transfected marrow stromal cells on expansion of human cord blood CD34(+) cells ex vivo. A co-culture system was established with FL gene transfected human marrow stromal cells and cord blood CD34(+) cells. The CD34(+) cells were cultured in different culture systems with different combinations of stromal cells and SCF, IL-3 and FL. The numbers of total nucleated cells, CFCs and CD34(+) cells were repeatedly counted in culture systems for 3 weeks. The results showed that the FL transgenic marrow stromal cell feeder layer significantly enhanced the expansion of total nucleated cells, CFC and CD34(+) cells, compared with stromal cell feeder layer and stromal cell-free culture systems. The transgenic stromal cells and cytokines co-culture system manifested the most potent expansion of the cord blood cells with increase of the number of total nucleated cells by (122.5 +/- 4.3)-fold, CFCs by (39.6 +/- 2.7)-fold and CD34(+) cells by (11.8 +/- 0.52)-fold. It is concluded that human umbilical cord blood CD34(+) cells can be extensively expanded ex vivo by using FL gene transfected stromal cells combined with cytokines.

Antigens, CD34↗

PubMed2003

[Blood lead level and related risk factors among children aged 0-6 years in Beijing].

OBJECTIVE: To observe blood lead level and related risk factors among children of 0 - 6-year old in Beijing. METHODS: Stratified-clustered-random sampling and simple random sampling were used. A total of 2 262 children of 0 - 6 years old were investigated from May to July 2001. They were permanent residents in Beijing. Blood lead level was tested by graphite atomizer absorption spectrophotometer. At the same time, related factors were investigated using a standardized questionnaire. RESULTS: The mean lead level of children in Beijing was 96.8 micro g/L with 35.7% of those >/= 100 micro g/L, and 2.5% >/= 200 micro g/L. The proportion of lead poisoning was significantly higher in rural children (P < 0.01). The proportion of lead poisoning in 2-year-old group was higher than that in other age groups. The proportion of lead poisoning in boys was significantly higher than that in girls (P < 0.01). The following factors might serve as major risk factors related to child lead poisoning, such as, never or rarely drinking milk, living in nearby highways (less than 50 meters) or living in the first floor/bungalow, and so on. CONCLUSION: The blood lead level of >/= 100 micro g/L among Beijing children appeared to be a big problem. Decision-makers should pay more attention to prevent blood lead level being high, and to cure these children who suffered in lead poisoning. Effective intervention measures on these target populations should be taken.

Child, Preschool↗