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Biomedical subjects

Li Wang

Publications and source records attributed to Li Wang.

482 records · Page 27Linked to original sources
PubMed2002

Lead can inhibit NMDA-, K(+)-, QA/KA-induced increases in intracellular free Ca2+ in cultured rat hippocampal neurons.

OBJECTIVE: To examine the effects of Pb2+ on N-methyl-D-aspartate (NMDA)-, K(+)- and quisqualate(QA)/kainite(KA)-induced increases in intracellular free calcium concentration ([Ca2+]i) in cultured fetal rat hippocampal neurons in order to explain the cognitive and learning deficits produced by this heavy metal. METHODS: Laser scanning confocal microscopy was used. RESULTS: The results clearly demonstrated that adding Pb2+ before or after NMDA/glycine stimulation selectively inhibited the stimulated increases in [Ca2+]i in a concentration-dependent manner. In contrast, Pb2+ treatment did not markedly affect increases in [Ca2+]i induced by an admixture of QA and KA. The minimal inhibitory effect of Pb2+ occurred at 1 mumol/L, and more than seventy percent abolition of the NMDA-stimulated increase in [Ca2+]i was observed at 100 mumol/L Pb2+. Evaluation of Pb(2+)-induced increase in [Ca2+]i response to elevating extracellular concentrations of NMDA, glycine or calcium revealed that Pb2+ was a noncompetitive antagonist of both NMDA and glycine, and a competitive antagonist of Ca2+ at NMDA receptor channels. In addition, Pb2+ inhibited depolarization-evoked increases in [Ca2+]i mediated by K+ stimulation (30 mumol/L), indicating that Pb2+ also depressed the voltage-dependent calcium channels. Also, the results showed that Pb2+ appeared to be able to elevate the resting levels of [Ca2+]i in cultured neurons, implying a reason for Pb(2+)-enhanced spontaneous release of several neurotransmitters reported in several previous studies. CONCLUSION: Lead can inhibit NMDA-, K(+)-, QA/KA-induced increases in intracellular [Ca2+]i in cultured hippocampal neurons.

Animals↗
PubMed2002

[Study of ABO blood group secretor type alpha(1,2)-fucosyltransferase gene polymorphism in Chinese].

Secretor gene (FUT2)-encoded secretor type alpha(1,2)-fucosyltransferase (Se enzyme) that regulates expression and secretion of ABO(H) antigens in epithelial cell of glands and body fluids. It has the extensive polymorphism and race specificity. In the present study, we investigated the distribution of the fusion gene of the FUT2 locus in 191 Manchu individuals from Liaoning Province and 208 Mongolian individuals from Inner Mongolia, and analyzed the polymorphism of the FUT2 gene in 90 unrelated Han Chinese from Shandong Province and 90 Mongolian from Inner Mongolia, respectively. The fusion gene was not found in the two investigated ethnic groups. The frequencies of G849A nonsense mutation in Shandong Han Chinese and Mongolian of Inner Mongolia individuals were the same, 0.0055.

China↗
PubMed2002

[Simultaneous determination of iron and molybdenum by extraction catalytic spectrophotometry].

In this paper, a new extraction catalytic spectrophotometric method for the simultaneous determination of iron and molybdenum has been studied. The method is based on the difference of the reaction rate of iron(III) and molybdenum(VI) catalyzed oxidation of o-aminophenol by hydrogen peroxide in weak acidic medium at pH 5.5. The reaction time, concentration of o-aminophenol in aqueous phase and degree of reaction are controlled by extraction equilibrium. The absorbance of organic phase is measured at 424 nm. The linear ranges of the method are 0.010-0.30 microgram.mL-1 (for iron) and 0.50-2.0 micrograms.mL-1 (for molybdenum). The method has been applied to the simultaneous determination of iron and molybdenum in soybean with satisfactory results.

Catalysis↗
PubMed2002

Ultrastructural localization of ATPase in mature tracheary elements of rice (Oryza sativa L.) stamen.

The development of mature tracheary elements (TEs) of rice (Oryza sativa L. cv. Nongkeng 58s-SD) stamen from big-vacuole to trinucleate pollen stage was studied with lead phosphate--deposition technique. At big-vacuole pollen stage, mature TEs, both in filament and connective, were short of ATPase activity. However, ATPase activity appeared at binucleate pollen stage; in filament, one or two vascular bundle cell (s) next to TE degenerated earlier than the rest; and the plasma membrane of degenerating cell (DC) always exhibited high ATPase activity on condition that the adjoining TE was of fully stretched second wall; when the second wall only turned up far off DC, the plasma membrane of DC still showed high ATPase activity except on borderline between DC and TE; in connective at the same stage, TEs also exhibited high ATPase activity, but the vascular bundle cell(s) adjoining TEs degenerated much later than their counterparts in filament. At trinucleate pollen stage, materials, either with or without ATPase activity, were observed both in filament and connective TEs. The above results indicated that (some of the) materials in mature TEs come from filament DC.

Adenosine Triphosphatases↗
PubMed2002

[A RAPD method acceptable for the analysis of mitochondrial gene expression].

Several techniques are available in detecting variations in gene expression between different samples, such as SSH, RACE, etc. However, they can not be applied to analyze mitochondrial gene expression due to the specific characteristics of mitochondrial RNA. So some modifications were made to the conventional techniques. Here we reported a demonstration of this modified technique, taking rice mitochondria as materials. In this technique, using random hexamers to prime the RT, the resultant cDNA likely included coding regions because it was not locked to the poly(A) tail of the messenger RNA.

English Abstract↗
PubMed2002

[A review on mitochondrial DNA of avian].

Mitochondrial DNA as a genetic marker has been successfully applied to the study of molecular evolution of birds. The apparently maternal inheritance of mitochondrial DNA and its fast evolution in primary sequence has made it attractive in population and evolutionary genetics. Mitochondrial DNA of birds displays two characteristics not seen in other vertebrates mtDNA, that is, a novel gene order and the absence of an equivalent to the light-strand replication origin. The research on polymorphism of mtDNA can resolve phylogenies of birds both at lower and higher taxonomic levels. Here we review progress on avian molecular evolution in recent years,and make preliminary studies of the development in this field.

English Abstract↗
PubMed2001

Association of a functional inducible nitric oxide synthase promoter variant with complications in type 2 diabetes.

Complications of diabetes have a genetic influence. Since increased inducible nitric oxide synthase (iNOS) gene ( NOS2A) expression can contribute to tissue damage, NOS2A is a worthy candidate for such a role. We therefore tested a 4-bp insertion/deletion (+/-) polymorphism 0.7 kb upstream of NOS2A for association with complications in type 2 diabetes patients, and also performed transient transfection experiments to examine the effect of this variant on promoter activity in kidney cells in culture. We investigated 379 Caucasian type 2 diabetes patients of British/European descent, 93 of whom had microalbuminuria, 26 overt nephropathy, 46 retinopathy, and 73 clinical neuropathy. Genotyping for the variant was carried out by PCR and automated Genescan analysis. Transient transfection studies involved the renal HEK 293 cell line and luciferase reporter gene constructs containing 1.1 kb of 5'-flanking DNA from '+' or '-' allele homozygotes. We found that the '+' allele frequency in patients without microalbuminuria was 12%, but was 23% in those with microalbuminuria ( P=0.0005), and was 26% in those with nephropathy ( P=0.0007), 22% in those with retinopathy ( P=0.037), and 23% in those with neuropathy ( P=0.045). The odds ratios for homozygote +/+ to have microalbuminuria or nephropathy were 2.4 (95% CI 1.4-4.2, P=0.0023) and 5.4 (95% CI 1.8-16, P=0.0009), respectively. Luciferase reporter gene constructs containing 1 kb of NOS2A promoter DNA for each allele were made and sequence analysis confirmed that the +/- variation was the only sequence difference present. Transient transfection of these into HEK 293 cells revealed 25 times higher reporter gene activity for the '+' allele compared with the '-' allele. Gel shift analysis with 30mer oligonucleotides corresponding to each allele showed specific binding to nuclear extracts, being greater for the '+' allele. Thus the '+' allele of the NOS2A promoter variant may confer higher iNOS expression, and could contribute to complications of type 2 diabetes, especially in the approximately 5% of patients homozygous for this variant.

Albuminuria↗
PubMed2000

[Expression of GATA-2 Gene and Immunoglobulin Heavy Chain Germline Gene C( micro ) in Leukemia Cells and Its Significance]

To investigate the significance of GATA-2 and immunoglobulin heavy chain germline gene C( micro ) (IgH germline gene C( micro )) expression and coexpression in various leukemia cells, GATA-2 and IgH germline gene C( micro ) mRNA in bone marrow and peripheral blood cells from 63 leukemia patients were detected by reverse transcription-polymerase chain reaction (RT-PCR). No GATA-2 or IgH germline gene C( micro ) mRNA were detected in normal bone marrow and peripheral blood. GATA-2 mRNA were be detected in 91.3% patients with acute myeloid leukemia (AML), 75% patients with acute lymphoblastic leukemia (ALL) as well as 83.3% patients with chronic myeloid leukemia (CML-CP); IgH germline gene C( micro ) mRNA were be identified in 47.8% AML, 41.6% ALL, as well as 5.6% CML-CP. All patients with CML-AP and CML-BC expressed GATA-2 mRNA and partly expressed IgH germline gene C( micro ) mRNA. 47.8% AML and 41.6% ALL patients coexpressed GATA-2 and IgH germline gene C( micro ) mRNA. GATA-2(+) IgH germline gene C( micro )(+) cells of AML and ALL were mainly HLA-DR positive. As aberration of the transcription factors, GATA-2 and germline IgH germline gene C( micro ) gene might been linked to leukemogenesis. Various expression of GATA-2 and germline IgH germline gene C( micro ) gene in leukemia might correlated with the heterogeneous differentiation level of leukemia cells. The fact that leukemia with GATA-2(+) IgH germline gene C( micro )(+) coexpression indicated multilineage impairment of hematopoietic cells.

Journal Article↗
PubMedDate not supplied

Genetic diversity and population structure of Lamiophlomis rotata (Lamiaceae), an endemic species of Qinghai-Tibet Plateau.

Lamiophlomis rotata (Lamiaceae), a perennial medicinal herb, is endemic to the Qinghai-Tibet Plateau. A total of 188 individuals from eight natural populations of L. rotata in Qinghai-Tibet Plateau (four from Tibet, two from Yunnan, and two from Qinghai) were analyzed using intersimple sequence repeats (ISSR) and randomly amplified polymorphic DNA (RAPD) techniques. Our results revealed that the level of genetic variation in L. rotata was relatively high (P = 94.85%, I = 0.440 +/- 0.220, H(T) = 0.289 +/- 0.028). Three genetic groups corresponding to the three geographic regions were detected, suggesting significant geographic structure. Our results suggest that the highly structured geographic pattern found in L. rotata might represent diverging evolutionary processes associated with the uplifting of the Qinghai-Tibet Plateau and Quaternary climatic oscillations. These findings imply that as many populations as possible should be preserved in situ for the conservation of this species. Given their genetic variability and peripheral distribution, Qinghai and Yunnan populations should be assigned priority for conservation. Optimal harvesting strategies, domestication and tissue culture of L. rotata should be developed as soon as possible to guarantee its sustainable use.

China↗
PubMedDate not supplied

Novel polyamine-dialkyl phosphate conjugates for gene carriers. Facile synthetic route via an unprecedented dialkyl phosphate.

To develop a novel nonviral gene carrier, three types of polyamine-dialkyl phosphates conjugates were synthesized via an unprecedented synthetic intermediate, dimerized dicetyl phosphate (DCP) anhydride, and the transfection efficiency and the complexation properties of the conjugate-DNA were evaluated. Condensation of DCP by 1,3,5-triisopropylbenzenesulfonyl chloride, TPSCl, gives the dimerized anhydride, which is stable enough to isolate by column chromatography in approximately 90% yield. The anhydride is reactive with various amines, i.e., spermidine, spermine, and polyethylenimine (PEI(1800)), providing corresponding polyamine-DCP conjugates via phosphoramidate linkage. The polyamine-DCP conjugates exhibited moderate transfection efficacy evaluated by beta-galactosidase assay. The conjugate-DNA complex was observed by using an atomic force microscope (AFM), revealing that the PEI(1800)-DCP conjugate, which showed the most efficient transfection, enables the formation of the more compact complex with DNA.

Animals↗
PubMedDate not supplied

Lipid phase control of DNA delivery.

Cationic lipids form nanoscale complexes (lipoplexes) with polyanionic DNA and can be utilized to deliver DNA to cells for transfection. Here we report the correlation between delivery efficiency of these DNA carriers and the mesomorphic phases they form when interacting with anionic membrane lipids. Specifically, formulations that are particularly effective DNA carriers form phases of highest negative interfacial curvature when mixed with anionic lipids, whereas less effective formulations form phases of lower curvature. Structural evolution of the carrier lipid/DNA complexes upon interaction with cellular lipids is hence suggested as a controlling factor in lipid-mediated DNA delivery. A strategy for optimizing lipofection is deduced. The behavior of a highly effective lipoplex formulation, DOTAP/DOPE, is found to conform to this "efficiency formula".

DNA↗
PubMedDate not supplied

High-throughput selection for heterogeneous catalysts.

A catalyst library of 80 samples with different mass ratios of rare earth elements, cobalt (Co), cerium (Ce), and indium (In), was prepared by impregnation of a fresh HZSM-5 zeolite support. A high-throughput detection setup, based on UV absorption spectroscopy, was developed for heterogeneous catalyst selection. The catalytic properties of the library were tested in the selective catalytic reduction of NO by methane at 673 K. Among the Co/Ce series, the catalyst with Co/Ce = 2:1 and Co/H-ZSM5 = 2.5% has shown remarkable efficiency (up to 78%). In the Ce/In series, the reactivity of the catalyst with the support composition of Ce/In = 1:1 and Ce/H-ZSM5 = 2.0% was < or = 88%. Our initial experiments definitely indicated that this simple and inexpensive multichannel setup can be applied for the selection of other heterogeneous catalysts. According to the variation of the UV light intensity, resulting from the absorption of the reactant or product, it was possible to monitor the relative quantity of reactants or products during a catalytic reaction.

Catalysis↗