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Biomedical subjects

Lei Wang

Publications and source records attributed to Lei Wang.

At least 361 records · Page 20Linked to original sources
PubMed2004

[Synthesis and degradation of the peanut storage proteins during seed development and germination].

Three polypeptides, 41 kD and 38.5 kD subunits of arachin and 60.5 kD subunit of conarachin in peanut (Arachis hypogaea L. Shanyou 523) seeds were purified by gel filtration and SDS-PAGE. Polyclonal antibodies against these subunits were raised in mice. Western blot showed that the subunits appeared in axes and cotyledons at the tissue differentiation stage. The 60.5 kD subunit was firstly synthesized and accumulated in considerable quantity in axes and cotyledons, and then the 41 kD and 38.5 kD subunits increased during the development of peanut embryos. The degradation patterns of these three subunits were different during the germination of peanut seeds. The 41 kD and 38.5 kD subunits in the axes and cotyledons were degraded earlier than the 60.5 kD subunit.

Allergens↗
PubMed2004

[Influence of liquid ceramic additive on binding of heavy metal during the vitrification of fly ash from municipal solid waste incinerator].

Vitrification process can effectively control the leachability of heavy metals in fly ash generated from municipal solid waste incinerator (MWSI). The use of liquid ceramic (LC) additive as a heavy metal chemical stabilization agent was evaluated for MSWI fly ash. The residuals of chromium, lead and zinc in slag increase by different degree with liquid ceramic additive at 1400 degrees C, while those of cadmium and copper decreases. The migrating characteristic of nickel is hardly affected by the additive less than 10%. The volatilization of Cr and Zn occurs after 61 minute with 10% addition of LC, and the binding efficiency of Cr decreases with increasing of melting temperature. The results indicate that the binding efficiency of heavy metals was affected greatly by LC additive and showed significant differences according to type of heavy metal during melting process. The short melting time (no longer than 33 min) is useful to obtain high binding efficiency of heavy metals.

Carbon↗
PubMed2004

[Sequence of Escherichia coli O141 O-antigen gene cluster and analyses of its evolutionary history].

Lipopolysaccharide (LPS) is one of the major components of the outer membrane of gram-negative bacteria. It is an amphipathic molecule compose of lipid A, a core oligosaccharide and an O-specific antigen. O-antigen, which is a repeat-unit polysaccharide, is a major contribution to the antigenic variability of the bacterial cell surface. The genes of O-antigen gene cluster are responsible for the synthesis of the O-antigen. The O-antigen gene cluster of E. coli O141 was sequenced and found to contain the genes rmlBDAC and manBC for the biosynthesis of nucleotide sugars dTDP-rhamnose and GDP-mannose, respectively, encoding genes for Ounit flippase (wzx), O-antigen polymerase (wzy) and potential transferase genes. The possible biosynthesis pathway for O-antigen of E. coli O141 was proposed. Two genes specific to E. coli O141 were identified. This work provides the basis for a sensitive test by PCR for the rapid detection of E. coli O141. Phylogenetic trees for the rmlB, rmlD, rmlA, and rmlC genes and manB, manC genes were generated and the comparisons were made among different strains. We find that these genes are typical E. coli genes and might have been involved in recombination events between O-antigen gene clusters.

Escherichia coli↗
PubMed2004

[Experiment of simultaneous denitrifying phosphorus accumulation].

Denitrifying phosphorus accumulation (DNPA) and the factors affecting it were studied in a SBR with synthetic wastewater. The results showed that the sludge acclimatized under anaerobic/aerobic operation with good phosphorus removal ability, showed DNPA soon when fed nitrate instead of aeration following the anaerobic stage. Anaerobic stage was a vital premise to DNPA. If DNPA sludge was fed with nitrate prior to anaerobic stage, the DNPA would weaken even disappear. When acetate was used as sole carbon resource in the influent and nitrate did not exist in anaerobic, 1 hour of anaerobic time was optimal. NO3- -concentration in the anoxic was one of the factors affecting DNPA. When nitrate concentration was advanced from 5mg/L to 20mg/L, the percentage of DNPA increased from 11.9% to 48.7% under the condition of anaerobic(2h)-anoxic(1h)-aerobic(2h). But when the NO3- -concentration was enhanced upwards of 20mg/L, the efficiency cannot be improved. Induced DNPA did not disappear even though there was aerobic stage following anoxic stage, but the shorter the aerobic stage lasted the higher proportions of phosphorus removal via DNPA to total removal.

Bacteria, Aerobic↗
PubMed2004

[Research on discrimination of 3D fluorescence spectra of phytoplanktons].

Six phytoplankton species belonging to four divisions, which may cause red tide, were selected and cultivated under different temperature (20 degrees C and 15 degrees C) and illumination (7000, 4100 and 1100 Lux) in lab. 3D fluorescence spectra were measured in each growth period. Discrimination of these phytoplanktons' 3D fluorescence spectra was explored using discriminant analyses. The result showed that discriminant analyses based on the principal component analysis of spectra data was an efficient method. Isochrysis galbana, Platymonas helgolanidica and Skeletonema costatuma can be discriminated effectively. Skeletonema costatuma, which is an diatom, can be distinguished from Alexandrium tamarense and Prorocentrum micans which belong to Dinophyta.

Diatoms↗
PubMed2004

[The reverse forearm flap pedicled with the ulnar branch of the ulnar artery].

OBJECTIVE: To introduce a new flap for the repair of soft tissue defects in the hand. METHODS: The distally pedicled ulnar flap is based on the ascending branch of the upper-wrist cutaneous branch of the ulnar artery. The retrograde flow is ensured by the dorsal carpal arch via the descending branch. RESULTS: From 2000 to 2003, the flap was used to treat 8 cases of hand defects, including 3 dorsal defects, 2 palmar defects and 3 the first web defects. All flaps survived and the appearance was satisfactory. CONCLUSIONS: The reverse forearm flap pedicled with the ulnar branch of the ulnar artery provides a long vascular pedicle. The donor site scar is aesthetically acceptable.

Adult↗
PubMed2004

[A Sinorhizoboium meliloti strain that can nodulate soybean plants].

Sinorhizobium meliloti XJ96077 was isolated from root nodules of alfalfa (Medicago sativa) in Xinjiang Region of China. Nodulation experiments showed that both soybean and alfalfa were effectively nodulated by XJ96077. The DNA (G+ C) mol% of strain XJ96077 was 61.9%. The DNA homologies of strain XJ96077 were 93% and 80% with S. meliloti USDA1002T and 042BM, respectively. These results showed that XJ96077 belongs to Sinorhizobium meliloti. To prove the capability of XJ96077 to nodulate both soybean and alfalfa, constitutively expressed green fluorescence protein gene gfp was introduced to XJ96077, and the recombinant strain XJ96077(G) was obtained. Root nodules of the soybean and alfalfa inoculated with XJ96077(G) and the expression of gfp were observed using the confocal laser scanning microscope. XJ96077 showed various nodulation capacities with different soybean cultivars.

Medicago sativa↗
PubMed2004

[Sequence of Escherichia coli O138 O-antigen gene cluster and gne identification by bioinformatics].

E. coli O138 is one of the enterotoxigenic Escherichia coli, causing the postweaning diarrhea and edema disease of weaned pigs. The O-antigen gene cluster of E. coli O138 was sequenced and found to contain the genes rmlB-DAC and gne, gna for the biosynthesis of nucleotide sugars dTDP-rhamnose and UDP-GalNAcA, respectively, genes encoding for O unit flippase(wzx), O-antigen polymerase(wzy) and 3 potential transferase genes. The possible biosynthesis pathway for rare UDP-GalNAcA was proposed. Two genes specific to E. coli O138 were identified. This work provides the basis for a sensitive test by PCR for the rapid detection of E. coli O138. Phylogenetic tree for Gne and GalE proteins was generated and comparisons were made among different strains, and results revealed that these proteins are similar in the second structure, and Gne of E. coli O138 was identified by bioinformatics.

Computational Biology↗
PubMed2003

Functional expression and characterization of an acidic actinoporin from sea anemone Sagartia rosea.

Src I is the first reported acidic actinoporin from sea anemone Sagartia rosea with a pI value of 4.8 and comprises 13.9% alpha-helix, 65.1% beta-sheet, and 18.2% random coil. For structure-function studies, Src I was expressed in Escherichia coli as a cleavable fusion protein. Recombinant Src I exhibited obviously hemolytic activity, but the fusion protein Trx-Src I almost lost its hemolytic activity, suggesting the importance of the N-terminal amphiphilic alpha-helix for its functional activity. The cytotoxic effects of Src I depending on the toxin concentration and incubation time were also observed on cultured cells. Among five cell lines: NIH/3T3, U251, NSCLC, BEL-7402, and BGC-823, NSCLC was the most sensitive cells with ID(50) 2.8 microg/ml and BGC-823 was the least sensitive cells with ID(50) 7.4 microg/ml. After incubated with lipid SUVs, such as SM-SUVs and SM/PC-SUVs, the hemolytic activity of Src I was inhibited to some extent. When incubated with calcein-entrapped lipid LUVs, such as SM-LUVs, SM/PC-LUVs, and SM/PG-LUVs, Src I induced release of entrapped calcein. According to the interaction with lipid vesicles, we proposed that it was the membrane matrix made up of phospholipids, not a particular phospholipid that facilitates Src I to react properly.

Amino Acid Sequence↗
PubMed2003

Determination of content uniformity and distribution characteristics of an investigational drug in its tablets dosage form and granule by ICP-AES.

An investigational drug (A) in its calcium salt form has been developed as the tablet dosage form. Monitoring drug distribution and uniformity in granules and tablets during early stage formulation/process development is critical for drug product quality control and process robustness. In this report, an efficient and reliable analytical method for monitoring drug compound A uniformity and distribution has been developed by analyzing calcium, the counter ion of the drug substance, by Inductively Coupled Plasma Atomic Emission Spectrometer (ICP-AES). In this method, calcium in compound A granule and tablet samples was digested with 1 M hydrochloric acid by heating at 90 degrees C for 2 h. The resulting suspension was centrifuged, and the supernatant was directly aspirated into an ICP-AES. This method has been validated to demonstrate satisfactory precision, accuracy, specificity and sensitivity. Finally, this method has been used to analyze sieve fraction granules and tablets of drug compound A. The data generated were highly comparable to those by validated HPLC methods (UV method can not be applicable due to significant bias). In comparison with HPLC methods, this method demonstrates a significantly improved efficiency with very short analysis time (1 min per sample), and can be used as an excellent alternative for UV and HPLC methods to support formulation screening.

Drugs, Investigational↗
PubMed2003

Hippocampal deformities in the unaffected siblings of schizophrenia subjects.

BACKGROUND: Neuroanatomical abnormalities have been reported in schizophrenia subjects and their relatives and may be related to genetic vulnerability. The objective of this study was to further elucidate hippocampal deformities as a marker of genetic vulnerability for schizophrenia. METHODS: Magnetic resonance scans were collected in 13 pairs of schizophrenics and their unaffected siblings from families with multiple affected members, in 12 schizophrenics from families without another affected member, and in 10 healthy controls. Hippocampal volume and shape were compared using large-deformation high-dimensional brain mapping. RESULTS: Decreases in hippocampal volume, covaried for total cerebral volume, were observed in the schizophrenia subjects from families with multiple affected members, as well as in their unaffected siblings. Shape analysis demonstrated that both groups of schizophrenia subjects, as well as the unaffected siblings, could be distinguished from the controls; however, no significant difference in hippocampal shape was found between the schizophrenia subjects and their unaffected siblings. Visualization of the pattern of hippocampal shape deformity in both groups of schizophrenia subjects and in the unaffected siblings showed inward deformities of the head of the hippocampus. CONCLUSIONS: Deformations of hippocampal anatomy may be related to the genetic vulnerability of acquiring schizophrenia.

Adult↗
PubMed2003

Cooperative dimerization of a heterocyclic diamidine determines sequence-specific DNA recognition.

In the course of a program aimed at discovering novel DNA-targeted antiparasitic drugs, the phenylfuran-benzimidazole unfused aromatic dication DB293 was identified as the first diamidine capable of forming stacked dimers in the DNA minor groove of GC-containing sequences. Its preferred binding sequence encompasses the tetranucleotide 5'-ATGA.5'-TCAT to which DB293 binds tightly with a strong positive cooperativity. Here we have investigated the influence of the DNA sequence on drug binding using two complementary technical approaches: surface plasmon resonance and DNase I footprinting. The central dinucleotide of the primary ATGA motif was systematically varied to represent all of the eight possible combinations (AXGA and ATYA, where X or Y = A, T, G, or C). Binding affinities for each site were precisely measured by SPR, and the extent of cooperative drug binding was also determined. The sequence recognition process was found to be extremely dependent on the nature of the central dinucleotide pair. Modification of the central TG step decreases binding affinity by a factor varying from 2 to over 500 depending on the base substitution. However, the diminished binding affinity does not affect the unique binding mode. In nearly all cases, the SPR titrations revealed a positive cooperativity in complex formation which reflects the ease of the dication to form stacked dimeric motifs in the DNA minor groove. DNase I footprinting served to identify additional binding sites for DB293 in the context of long DNA sequences offering a large variety of randomly distributed or specifically designed sites. The ATGA motif provided the best receptor for the drug, but lower affinity sequences were also identified. The design of two DNA fragments composed of various targeted tetranucleotide binding sites separated by an "insulator" (nonbinding) sequence allowed us to delineate further the influence of DNA sequence on drug binding and to identify a novel high-affinity site: 5'-ACAA.5'-TTGT. Collectively, the SPR and footprinting results show that the consensus sequence 5'-(A/T)-TG-(A/T) represents the optimal site for cooperative dimerization of the heterocyclic diamidine DB293.

Base Sequence↗
PubMed2003

Full-length RAG-2, and not full-length RAG-1, specifically suppresses RAG-mediated transposition but not hybrid joint formation or disintegration.

RAG-1 and RAG-2 initiate V(D)J recombination by introducing DNA breaks at recombination signal sequences flanking a pair of antigen receptor gene segments. Occasionally, the RAG proteins mediate two other alternative DNA rearrangements in vivo: the rejoining of signal and coding ends and the transposition of signal ends into unrelated DNA. In contrast, truncated, catalytically active "core" RAG proteins readily catalyze these reactions in vitro, suggesting that full-length RAG proteins directly or indirectly suppress these undesired reactions in vivo. To discriminate between direct and indirect suppression models, full-length RAG proteins were purified and characterized in vitro. From mammalian cells, full-length RAG-1 is readily purified with core RAG-2 but not full-length RAG-2 and vice versa. Despite differences in DNA binding activity, recombinase containing either core or full-length RAG-1 or RAG-2 possess comparable cleavage, rejoining, and end-processing activity, as well as similar usage preferences for canonical versus cryptic recombination signals. However, recombinase containing full-length RAG-2, but not full-length RAG-1, exhibits dramatically reduced transposition activity in vitro. These data suggest RAG-mediated transposition and rejoining are differentially regulated by the full-length RAG proteins in vivo (the former directly by RAG-2 and the latter indirectly through other factors) and argue that noncore portions of the RAG proteins have little or no direct influence over V(D)J recombinase site specificity.

Base Sequence↗
PubMed2003

Mycobacterial heat shock protein 65 enhances antigen cross-presentation in dendritic cells independent of Toll-like receptor 4 signaling.

Heat shock proteins (HSP) have been shown to enhance antigen processing and presentation through their association with antigenic peptides and delivery of these moieties into major histocompatibility complex class I pathways. In this study, mycobacterial Hsp65 is demonstrated to have the ability to help cross-present an exogenous protein by dendritic cells (DC) to CD8 T cells without the need for complex formation between Hsp65 and the protein. This ability of Hsp65 to enhance cross-presentation is independent of its weak stimulatory effect on DC, the latter seen only after prolonged incubation. When the effect of lipopolysaccharide contamination is abrogated, Hsp65 is unable to activate Toll-like receptor (TLR)4 in the presence of CD14 and MD2. This accounts for the inability of Hsp65 to drive maturation of DC and shows that Hsp65 is not a potent stimulator of DC. Thus, Hsp65 enhances the cross-presentation of a soluble, free antigen by DC, independent of TLR4 signaling and up-regulation of costimulatory molecules.

Antigen Presentation↗
PubMed2003

Suppression of in vitro megakaryocyte production by antiplatelet autoantibodies from adult patients with chronic ITP.

Chronic immune thrombocytopenic purpura (ITP) is manifested by autoantibody-induced platelet destruction. Platelet turnover studies suggest that autoantibody may also affect platelet production. To evaluate this, we studied the effect of plasma from adult patients with chronic ITP on in vitro megakaryocyte production. CD34(+) cells, obtained from healthy donors, were cultured in medium containing PEG-rHuMGDF and 10% plasma from either ITP patients or healthy subjects. Cultures containing plasma from 12 of 18 ITP patients showed a significant decrease (26%-95%) in megakaryocyte production when compared with control cultures. Positive ITP plasmas not only reduced the total number of megakaryocytes produced during the culture period but also inhibited megakaryocyte maturation, resulting in fewer 4N, 8N, and 16N cells. The role of antibody in this suppression is supported by 2 factors: (1) immunoglobulin G (IgG) from ITP patients inhibited megakaryocyte production when compared with control IgG; and (2) adsorption of autoantibody, using immobilized antigen, resulted in significantly less inhibition of megakaryocyte production when compared with unadsorbed plasma. These results show that plasma autoantibody from some adult patients with ITP inhibits in vitro megakaryocyte production, suggesting that a similar effect may occur in vivo.

Adult↗
PubMed2003

Photomutagenicity of cosmetic ingredient chemicals azulene and guaiazulene.

The photomutagenicity of the popular skin conditioning agents azulene and guaiazulene were tested in Salmonella typhimurium TA98, TA100 and TA102. Following irradiation with UVA and/or visible light, both azulene and guaiazulene exhibited mutagenicity 4-5-fold higher than the spontaneous background mutation. In contrary, naphthalene, a structural isomer of azulene, was not photomutagenic under the same conditions. Azulene was photomutagenic when irradiated with UVA light alone, visible light alone, or a combination of UVA and visible light. Azulene and guaiazulene are not mutagenic when the experiment is conducted with the exclusion of light. Therefore, extreme care must be taken when using cosmetic products with azulene/guaiazulene as ingredients since after applying these products on the skin, exposure to sunlight is inevitable.

Azulenes↗