Biomedical subjects

Gang Wei

Publications and source records attributed to Gang Wei.

At least 37 records · Page 2Linked to original sources

PubMed2005

One-step synthesis of silver nanoparticles, nanorods, and nanowires on the surface of DNA network.

Here, we describe a one-step synthesis of silver nanoparticles, nanorods, and nanowires on DNA network surface in the absence of surfactant. Silver ions were first adsorbed onto the DNA network and then reduced in sodium borohydride solution. Silver nanoparticles, nanorods, and nanowires were formed by controlling the size of pores of the DNA network. The diameter of the silver nanoparticles and the aspect ratio of the silver nanorods and nanowires can be controlled by adjusting the DNA concentration and reduction time.

DNA↗

PubMed2005

Observation of the mica surface by atomic force microscopy.

Freshly cleaved mica and a mica surface treated with pure water and dilute-salt solution have been investigated by Atomic Force Microscopy (AFM). On the bare mica surface (after repeated scanning), small dots and islands were observed. The disappearance of these dots and islands has also been captured by AFM. We believe these structures to be condensed water. The water meniscus between AFM tip and mica surface is considered as the source of this water structure. On the mica surface treated with pure water and dilute-salt solution, network structures are frequently observed by AFM.

Journal Article↗

PubMed2005

Interaction of cobalt(II) and nickel(II) with a gamma-linked, bis-beta-diketone ligand to yield an unusual coordination motif.

Discrete cobalt(II) and nickel(II) complexes of type ML (where L is a bis(2,4-pentanedionate) derivative incorporating a -SCH2CH2S- bridge between the gamma-carbons of respective beta-diketone units) have been synthesised and represent the first examples in which a gamma-substituted, thioether-containing beta-diketone ligand coordinates via a sulfur and oxygen donor in preference to the classical coordination mode involving both beta-diketonate oxygens.

Journal Article↗

PubMed2005

Imaging DNA molecules on mica surface by atomic force microscopy in air and in liquid.

DNA molecules immobilized on mica surface by various methods have been observed by atomic force microscopy both in air and in liquid. Divalent cations and 3-aminopropyltriethoxysilane (APTES) modified mica surface have been used to immobilize the DNA molecules. Optimal DNA and divalent cations concentration for AFM imaging are presented. Among the different methods of modifying mica surface with APTES, the water solution modifying method appears to get the best results. When using high DNA concentration for AFM imaging, DNA networks can be formed. A simple method to extend long DNA molecules is demonstrated. The optimal imaging conditions and AFM operating techniques are discussed. Different DNA immobilizing methods have been compared and evaluated.

Air↗

PubMed2005

Insights into selective activation of p53 DNA binding by c-Abl.

As a transcription factor, p53 recognizes a specific consensus DNA sequence and activates the expression of the target genes involved in either growth arrest or apoptosis. Despite our wealth of knowledge on the genes that are targeted by p53 in growth arrest and apoptosis, relatively little is known about the promoter specificity triggered by p53 in these processes. Here we show that interaction with c-Abl stabilized p53 tetrameric conformation, and as a consequence c-Abl stimulated p53 DNA binding only when all quarter binding sites (a perfect binding sequence) on p53-responsive promoters were present. This result suggests that in response to DNA damage, c-Abl binding may specifically stimulate p53 DNA binding on the promoters with perfect binding sequences. A sequence comparison of several known p53-responsive elements illustrates the presence of the perfect binding sequences on the p21 but not the Bax promoter. Significantly, we show that c-Abl indeed enhanced p53 DNA binding and transcription from p21 but not Bax. These results suggest that the promoter specificity plays an important role in selective activation of p53 DNA binding by c-Abl. The implications of this with relation to selective activation of p53 target genes involved in either growth arrest or apoptosis are discussed.

Apoptosis↗

PubMed2005

Mechanically engraved mica surface using the atomic force microscope tip facilitates return to a specific sample location.

By controlling the interaction between the atomic force microscope tip and mica, patterns of different sizes and shape have been produced on the surface of mica. Using these operator-constructed patterns as a reliable marker, the original scanned sample location can be re-located and imaged again on the same mica surface by atomic force microscopy (AFM). This location technique can be used to find the same object again even if the sample was removed from the AFM instrument or the sample was imaged in a different mode.

Aluminum Silicates↗

PubMed2005

Immobilization of DNA on 11-mercaptoundecanoic acid-modified gold (111) surface for atomic force microscopy imaging.

Immobilized DNA on preformed 11-mercaptoundecanoic acids (MUDA) self-assembled monolayers (SAMs) on a gold (111) surface was bound by a divalent cation bridges was imaged by atomic force microscopy (AFM). The DNA immobilization was attributed to the formation of ionic bridges between the carboxylate groups of MUDA and the phosphate groups of DNA. AFM images revealed that DNA molecules could be immobilized strongly enough to permit stable and reproducible imaging. The effect of different bridge cations, such as Mg(2+), Zn(2+) and Cu(2+), and the pH of DNA assembled solution on immobilization and conformation of DNA was studied. Plasmid DNA pBR 322/Pst I molecules were straightened by using a molecular combing technique on the MUDA surface.

DNA↗

PubMed2005

Purification of acetyl-p53 using p300 co-infection and the baculovirus expression system.

As cells persist in their environment, they are exposed to harmful agents that can damage their genomic DNA. When DNA becomes damaged, p53, a tumor suppressor, is stabilized and acts as a transcription factor to cause either cell cycle arrest or apoptosis. Strict p53 regulatory mechanisms have been well characterized relative to phosphorylation and dephosphorylation, but acetylation of p53 in response to DNA damage has also been shown to participate in p53 function. Proper investigation of the many roles that acetylated p53 plays in the cell requires accurate in vitro studies, which can only be easily conducted if highly pure acetyl-p53 is available. Purified p53 that is acetylated in vitro can routinely achieve 10-20%. Separating this acetylated fraction from the undesired unacetylated fraction can be technically challenging, inefficient, and time consuming. We have developed an in vivo strategy to rapidly produce microgram quantities of p53 preparations that are greater than 60% acetylated using co-infection of p53 and p300 baculoviruses in Sf21 insect cell culture. Immunoaffinity recovery followed by further depletion of unacetylated p53 results in a preparation that is greater than 70-75% in acetyl-p53 after a single round, and undetectable levels of unacetylated p53 after two rounds. This approach to preparing acetylated protein in vivo may also extend to other acetylated transcription factors and histones.

Acetylation↗

PubMed2005

Epidemic viral gastroenteritis in Queensland coincides with the emergence of a new norovirus variant.

Norovirus infections cause widespread morbidity and have significant economic impact on the community. An increase in outbreaks of norovirus gastroenteritis in hospitals, nursing homes and in the community was observed in Queensland in 2004. Molecular analysis of positive samples indicated the emergence of a single strain of norovirus. A 252 nucleotide sequence from the polymerase region (POL) was compared to sequences of the new variant genotype GII.4 that has caused epidemics in the Northern Hemisphere in 2002 and 2003. Sequence analysis indicated greater than 95 per cent similarity in the POL between the Queensland strain and the Northern Hemisphere 2002/3 GII.4 variant. Phylogenetic analysis revealed that the Queensland strain forms a branch within the GII.4 genotype separate from the 2002 variant from Europe and North America. Although norovirus genotype GII.4 had circulated in Queensland in the past, the 2004 strain was characterised specifically by three nucleotides not present in any other sequences held in our database covering the years 2002-June 2004.

Caliciviridae Infections↗

PubMed2004

Photochromic inorganic-organic multilayer films based on polyoxometalates and poly(ethylenimine).

Novel photochromic inorganic-organic multilayers composed of polyoxometalates and poly(ethylenimine) have been prepared by the layer-by-layer (LbL) self-assembly method. The growth process, composition, surface topography, and photochromic properties of the multilayer films were investigated by UV-visible and Fourier transform infrared spectroscopy, atomic force microscopy, electrospin resonance (ESR), and X-ray photoelectron spectroscopy (XPS). Irradiated with ultraviolet light, the transparent films changed from colorless to blue. Moreover, the blue films showed good reversibility of photochromism and could recover the colorless state gradually in air, where oxygen plays an important role in the bleaching process. On account of the ESR and XPS results, parts of W6+ in multilayers were reduced to W5+, which exhibited a characteristic blue; a possible photochromic mechanism can be speculated. This work provides basic guideline for the assembly of multilayers with photochromic properties.

Journal Article↗

PubMed2004

Brief communication: American ginseng reduces warfarin's effect in healthy patients: a randomized, controlled Trial.

BACKGROUND: People using prescription medication often concurrently take herbal supplements. In a case report, the anticoagulant effect of warfarin decreased after patients consumed ginseng. OBJECTIVE: To evaluate the interactions between American ginseng and warfarin. DESIGN: Randomized, double-blind, placebo-controlled trial. SETTING: General Clinical Research Center, University of Chicago, Chicago, Illinois. PARTICIPANTS: 20 healthy patients. INTERVENTION: In this 4-week study, 20 patients received warfarin for 3 days during weeks 1 and 4. Beginning in week 2, patients were assigned to receive either American ginseng or placebo. MEASUREMENTS: International normalized ratio (INR) and plasma warfarin level. RESULTS: The peak INR statistically significantly decreased after 2 weeks of ginseng administration compared with placebo (difference between ginseng and placebo, -0.19 [95% CI, -0.36 to -0.07]; P = 0.0012). The INR area under the curve (AUC), peak plasma warfarin level, and warfarin AUC were also statistically significantly reduced in the ginseng group as compared with the placebo group. Peak INR and peak plasma warfarin level were positively correlated. LIMITATIONS: The study sample consisted of young, healthy volunteers in a research setting rather than patients taking therapeutic doses of warfarin. CONCLUSIONS: American ginseng reduces warfarin's anticoagulant effect. When prescribing warfarin, physicians should ask patients about ginseng use.

Adult↗

PubMed2004

Three-ring, branched cyclam derivatives and their interaction with nickel(II), copper(II), zinc(II) and cadmium(II).

The interaction of two symmetrically branched tris-cyclam derivatives based on 1,3,5-trimethylenebenzene and phloroglucinol cores with nickel(II), copper(II), zinc(II) and cadmium(II) is reported. All four metal ions yield solid complexes in which the metal : ligand ratio is 3 : 1. For both ligand types, spectrophotometric titrations confirm the formation of nickel(II) and copper(II) complexes of similar 3 : 1 stoichiometry in dimethyl sulfoxide. Visible spectral, electrochemical, magnetic moment, ESR and NMR studies have been performed to probe the nature of the respective complexes. Where appropriate, the results from the above metal-ion studies are compared with those from parallel investigations in which the corresponding (substituted) mono-cyclam analogues were employed as the ligands. A structural determination employing a poorly diffracting crystal of the trinuclear nickel(II) complex of the tris-cyclam ligand incorporating a 1,3,5-trimethylenebenzene core was successfully carried out with the aid of a synchrotron radiation source. A nickel ion occupies each cyclam ring in a square-planar coordination arrangement, with each cyclam ring adopting the stable trans-III configuration.

Journal Article↗

PubMed2004

Analysis of five differentially expressed gene families in fast elongating cotton fiber.

Using the suppression subtractive hybridization method, we isolated five gene families, including proline-rich proteins (PRPs), arabinogalactan proteins (AGPs), expansins, tubulins and lipid transfer proteins (LTPs), from fast elongating cotton fiber cells. Expression profile analysis using cDNA array technology showed that most of these gene families were highly expressed during early cotton fiber developmental stages (0 C20 days post anthesis, DPA). Many transcripts accumulated over 50-fold in 10 DPA fiber cells than in 0 DPA samples. The entire gene family --AGP, together with 20 individual members in other 4 gene families, are reported in cotton for the first time. Accumulation of cell wall proteins, wall loosening enzymes, microtubules and lipid transfer protein may contribute directly to the elongation and development of fiber cells.

Amino Acid Sequence↗

PubMed2004

The protein encoded by cancer/testis gene D40/AF15q14 is localized in spermatocytes, acrosomes of spermatids and ejaculated spermatozoa.

We have previously identified and cloned a human gene, D40, that is preferentially expressed in testis among normal organs, while it is widely expressed in various human tumor cell lines and primary tumors derived from different organs. In this report, we have examined the expression and localization of this protein in human testis with an antibody specific to D40 protein. In Western analyses, the anti-D40 antibody recognized a major band with a molecular mass of 300 kDa and a minor band of 250 kDa. These bands were not observed in the testis lysates from patients with Sertoli-cell-only syndrome and with Kleinfelter syndrome, who lack germ cells of the testis, indicating that D40 protein is expressed in the germ cells of normal testis. Immunohistochemical studies have revealed that D40 protein is highly expressed in spermatocytes and in the pre-acrosome of round spermatids. In the acrosome, D40 protein expression is observed not inside but outside the acrosome membrane. This is consistent with the finding that the amino-acid sequence at the amino terminal of the D40 protein lacks a hydrophobic signal peptide that is required for proteins to translocate to the membrane. Expression of D40 protein is observed in the acrosome of ejaculated spermatozoa as well, although the level is low compared with that in the pre-acrosome of spermatids. These results suggest that D40 protein plays important roles in spermatogenesis, especially in the formation and maintenance of the acrosome.

Acrosome↗

PubMed2004

[Clinical study on value of severity of patient with coronary artery disease evaluated with the thrombosis in myocardial infarction risk score].

OBJECTIVE: To explore the value of severity evaluating and outcome predicting on coronary artery disease (CAD) patients scored with the thrombosis in myocardial infarction (TIMI) risk score. METHODS: All of 126 patients with CAD were enrolled in study. TIMI risk score and coronary artery angiographic in them were performed respectively. Correlativity between TIMI risk score and clinical type of CAD, narrow severity, pathological changes limits and character of coronary artery were analyzed. Difference of scores of TIMI, narrow severity, pathological changes limits and character of coronary artery were compared among stable angina (SA), unstable angina (UA), un-ST-segment elevation myocardial infarction (NSTEMI) and ST-segment elevation myocardial infarction (STEMI) respectively. RESULTS: TIMI risk score significantly correlated with clinical type of CAD score, narrow severity score, pathological changes limits and character scores of coronary artery respectively (r=0.607 for narrow severity score, 0.569 for pathological changes limits score, 0.367 for pathological changes character score, all P<0.05). TIMI risk score increased company with severity of coronary artery pathological changes advancing. Significantly differences were found when TIMI risk scores were compared between SA and UA, NSTEMI and STEMI respectively as well as narrow severity scores (all P<0.05). Same RESULTS: were found between UA and NSTEMI, STEMI respectively (all P<0.05). There had no significantly difference among pathological changes limits scores of SA, UA, NSTEMI, STEMI (all P>0.05). Significantly difference was found when pathological changes character scores were compared between SA and UA, NSTEMI, STEMI respectively as well as narrow severity scores (P<0.05), but contrary RESULTS: were found between UA and NSTEMI, STEMI respectively (P>0.05). CONCLUSION: TIMI risk score not only could be used to predict the possibility of heart accident, but also could be used to evaluate clinical type of CAD, narrow severity, pathological changes limits and character of coronary artery in CAD patient.

Adult↗

PubMed2004

[Diffusion behaviors of drugs in thermosensitive in situ gels].

AIM: To study the diffusion behaviors of drugs in thermosensitive in situ gels, and provide valuable information for designing such delivery systems. METHODS: A free diffusion model was used to evaluate the effects of concentration, the property of drugs, as well as the gel compositions on the diffusivity of drugs. RESULTS: Drug transport through the aqueous channels of the gel followed Fickian mechanism, and no significant influence on the diffusivity was observed when the drug concentration was lowered from 5% to 0.25%. The diffusion coefficients of propranolol, timolol maleate, and salbutamol sulfate were 0.91, 1.32, and 3.30 x 10(-6) cm2 x s(-1), respectively. The flux of hydrophilic drug was 3.6 fold faster than that of the lipophilic one implied the latter partitioned into the hydrophobic micellar core, and consequently the diffusion was retarded. The diffusivity was decreased with increased poloxamer and sodium hyaluronate concentration, due to the distorted aqueous channels and higher microviscosity. CONCLUSION: The result suggested that sustained release could be achieved for the thermosensitive in situ gel by incorporating lipophilic drug or increasing polymer concentration.

Albuterol↗

PubMed2004

[Study on GC-MS fingerprint analysis in rhizome of volatile oil of Acorus tatarinowii].

OBJECTIVE: To establish the method of fingerprint analysis on volatile oil in rhizome of Acorus tatarinowii by GC-MS, and to study the main characteristic components. METHOD: The main components of 10 samples were determined by GC-MS. RESULT: The injector temperature was 250 degrees C. The interface temperature was 230 degrees C. The column flow was 1.3 mL x min(-1). The column pressure was 80 kPa. The detector volt was 1.4 kV. The temperature rate was 3 degrees C x min(-1). And the main characteristic components were composed of the methyleugenol (2.13%), cis-methylisoeugenol (4.48%), trans-methylisoeugenol (0.82%), gamma-asarone (4.51%), beta-asarone (66.15%), alpha-asarone (6.35%). And the RSD of precision and reproducibility and stability was almost in the range of 5%. CONCLUSION: The method is reliable, accurate and can be used for fingerprint analysis of volatile oil of Acorus tatarinowii.

Acorus↗

PubMed2004

[Investigation on the influential factors of the volatile oil and main constituent content in Pogostemon cablin].

OBJECTIVE: To provide scientific basis for quality evaluation by investigating the influential factors of the volatile oil and main constituent content in Pogostemon cablin. METHOD: Several experiments were carried out to test different habitats, collection periods, processing methods, the level of spreading manure and using agricultural chemical with the volatile oil assay of pharmacopoeia and GC-MS method. RESULT: The effect of different habitats, collection periods, processing methods on volatile oil and main constituent content was shown significantly. CONCLUSION: Such factors as different habitats, collection periods, processing methods should be taken into account when the quality standard of medicinal materials was made.

Ecosystem↗