Biomedical subjects

Yi Ding

Publications and source records attributed to Yi Ding.

At least 91 records · Page 5Linked to original sources

PubMed2004

Two novel dicoumaro-p-menthanes from Gerbera piloselloides (L.) CASS.

Two new type dicoumarins (dicoumaro-p-menthanes), named dibothrioclinins I (1) and II (2) were isolated from the roots and rhizomes of Gerbera piloselloides (L.) CASS., collected in Yunnan Province, China. Their structures were elucidated on the basis of MS, 1D ((1)H-NMR, (13)C-NMR, DEPT and NOE) and 2D ((1)H-(1)H COSY, HMQC, HMBC) NMR spectral analyses. The relative structures of the two compounds were established by NOE difference spectroscopy and further confirmed by single-crystal X-ray diffraction studies.

Asteraceae↗

PubMed2004

[Expression of MAGE genes and MAGE gene products in human renal and urinary bladder tumor].

OBJECTIVE: To observe the expression of MAGE-1 MAGE-3 genes and MAGE-3 gene product in renal and urinary bladder tumor, and to explore the possibility of MAGE-1 and MAGE-3 genes encoding proteins or MAGE-3 gene product used as a target for immunotherapy in renal and urinary bladder tumor patients. METHODS: Reverse transcriptase polymerase chain reaction for MAGE-1 and MAGE-3 genes was performed using 39 renal and urinary bladder tumor specimens. Immunohistochemical technique for MAGE-3 antigen was performed using formal infixed paraffin embedded section of 121 renal and urinary bladder tumor specimens. RESULTS: MAGE-1 and MAGE-3 mRNAs were detected in 23(59.0%) and 22(56.4%) of 39 patients with renal and urinary bladder tumor without expression in 10 tumor surrounding tissues.MAGE-3 antigen was detected in 56(46.3%) of 121 patients with renal and urinary bladder tumor without expression in 10 tumor surrounding tissues. The expression rates of MAGE-1 and MAGE-3 mRNA and MAGE-3 gene product were significantly higher in renal and urinary bladder tumors tissues than in tumor surrounding tissues. The frequency of MAGE-3 gene product expression was examined according to clinical stage and differentiation of histopathology. The results revealed no significant differences in MAGE gene product expression among the clinical stage and the grade of differentiation of histopathology according to Logistic Regression test(P>0.05). CONCLUSION: The tumor-specific antigens might be used as molecular markers and targets for human renal and urinary bladder tumor.

Adult↗

PubMed2004

[Expression of hMSH2 gene in esophageal cancer].

OBJECTIVE: To observe the expression of DNA mismatch repair gene hMSH2 mRNA in esophageal cancer tissues. METHODS: This study included 32 esophageal cancer patients who received no previous radiotherapy, chemotherapy or other treatments. Within 30 min following surgical removal of the tumor tissues, specimens of the tumor, the tissue adjacent to the tumor and normal tissue at the esophageal stump (1 cmx1 cmx1 cm in size for each specimen) were obtained for examining hMSH2 expression with hMSH2 ISH detection kit. RESULTS: The positivity rate of hMSH2 was 46.88% in the esophageal cancer tissues, 53.12% in the adjacent tissues, and 84.38% in normal tissues at the esophageal stump, showing significant difference of the former two tissues from the normal tissue (P<0.05). No significant correlation was noted between the positivity rate of hMSH2 and such factors as the patients' age, sex, tumor size, tumor location, pathological type, histological grade, lymphatic metastasis or degree of tumor invasion (P>0.05). CONCLUSION: The deletion of hMSH2 is an early event in the development of esophageal cancer.

Aged↗

PubMed2004

[Purification and characterization of sanguicin--a bacteriocin produced by Streptococcus sanguis].

OBJECTIVE: Streptococcus sanguis plays an important Role in maintaining the periodontal microecological balance. Previous studies have demonstrated that sanguicin--a kind of bacteriocin produced by S. sanguis has a prominent function of inhibiting the growth of putative periodontopathic bacteria (PPB). The aim of this study was to purify sanguicin and investigate its characters. METHODS: The raw extract of sanguicin was obtained from cells of S. sanguis by ultrasonication, salting out and dialysis. Then the diethyl-aminoethyl-sepharose gradual washing was done in conjunction with glucosan gel filtration for in the purfication of sanguicin. The characters of purified sanguicin were determined and its inhibitiory effect on PPB was measured by agar diffusion test. RESULTS: The purifed sanguicin was obtained; it was heat labile and proteinaceous; and by SDS-PAGE, it showed a main band with the relative molecular mass of 65 x 10(3). The purifed sanguicin had a strong inhibitory effect on P. gingivalis, P. intermedia and F. nucleatum in vitro. CONCLUSION: Our methods are useful for the purification of sanguicin. Sanguicin has inhibitory effect on PPB obviously and will have a good prospect in periodontal ecological therapy.

Anti-Bacterial Agents↗

PubMed2004

[A comparison between the effects of periocline and yakang on the treatment of periodontitis].

OBJECTIVE: To compare the efficacy of 2 available periodontal systems for local delivery of antibiotics. METHODS: 26 teeth with moderate to severe periodontitis (PD > or = 4 mm) from 11 patients were selected. The teeth were randomly divided into test group and control group. Periocline (2% minocycline hydrochoride ointment) was applied to the teeth in the test group, while Yakang (local metronidazole) was applied in the control group. The data including clinical indices and microbiological parameters was collected before and on the 7th, 14th day after the therapy. RESULTS: Before treatment, the mean of each clinical indices and microbiological parameters between the two groups was not different (P > 0.05). But both groups demonstrated significant differences with control after treatment (P < 0.05), while there were no significant differences between the two test groups (P > 0.05). CONCLUSION: Both Periocline and Yakang were effective and secure local delivery drug for treating periodontitis.

Anti-Bacterial Agents↗

PubMed2004

[Anesthetic efficacy of 2% mepivacaine in conservative dentistry].

OBJECTIVE: To determine the efficacy of 2% mepivacaine in conservative dentistry. METHODS: The patients who needed cavity preparation or access to pulp chamber received local infiltration with 2% mepivacaine. Anesthesia time, anesthetic efficacy and cardiovascular system influences were assessed. 3% lidocaine with epinephrine served as control. RESULTS: In experiment group, the anesthesia effects were quicker and anesthesia duration was longer than that in control group. Doctors highly appreciated the anesthetic efficacy. Two groups did not show any evident change in blood pressure and heart rate. CONCLUSION: 2% mepivacaine is a safe and efficacious local anesthetic drug in conservative dentistry.

Adolescent↗

PubMed2004

[Gap features of subalpine dark coniferous forest in Wolong Nature Reserve].

This paper studied the size structure and formation pattern of gaps and the characteristics of gap makers (GM) in subalpine dark coniferous forests in Wolong Giant Panda Nature Reserve, Sichuan Province, China. The results showed that the gap density was 18.5 per hm2, and the area of canopy gap and extended gap accounted for 28.4% and 60% of total forest area, respectively. Canopy gap varied from 10 m2 to 1134.7 m2, and expanded gap varied from 84.11 m2 to 1646.3 m2. Canopy gaps and expanded gaps had an average area of 153.45 m2 and 324.34 m2, respectively. The average number of gap makers (GM) per gap was 5.14, and only 8.1% of all gaps were created by just one GM. The order of GM contributed to gap formation was trunk snap > uproot > standing death > branch breakage. Abies faxoniana, Tsuga chinensis, and Betula utilis were the major gap makers, while Abies faxoniana in the canopy layer with 60-70 cm DBH and 30-35 m high had the greatest probability of gap making.

Abies↗

PubMed2004

[Chemical constituents from the rhizoma of Arundina graminifolia].

OBJECTIVE: To isolate and elucidate the chemical constituents from the tuber of Arundina graminifolia. METHOD: The compounds were extracted by 95% alcohol and isolated by column chromatography on silica gel, SephedaxLH-20 and ODS. The structures were determined by UV, IR, NMR and MS spectral analysis. RESULT: Five compounds were isolated, and their structures were identified as (2E)-, 2-propenoic acid, 3-(4-hydroxy-3-methoxyphenyl)-decosyl ester (I), p-hydroxybenzyl alcohol (II), triacontanol (III) and p-hydroxybenzylethyl ether (IV), 3-hydroxy-5-methoxybibenzyl (V), respectively. CONCLUSION: All compounds were isolated from the genus of Arundina for the first time.

Benzyl Alcohols↗

PubMed2003

The crystal structures of severe acute respiratory syndrome virus main protease and its complex with an inhibitor.

A newly identified severe acute respiratory syndrome coronavirus (SARS-CoV), is the etiological agent responsible for the outbreak of SARS. The SARS-CoV main protease, which is a 33.8-kDa protease (also called the 3C-like protease), plays a pivotal role in mediating viral replication and transcription functions through extensive proteolytic processing of two replicase polyproteins, pp1a (486 kDa) and pp1ab (790 kDa). Here, we report the crystal structures of the SARS-CoV main protease at different pH values and in complex with a specific inhibitor. The protease structure has a fold that can be described as an augmented serine-protease, but with a Cys-His at the active site. This series of crystal structures, which is the first, to our knowledge, of any protein from the SARS virus, reveal substantial pH-dependent conformational changes, and an unexpected mode of inhibitor binding, providing a structural basis for rational drug design.

Amino Acid Chloromethyl Ketones↗

PubMed2003

Dibothrioclinin I and II, epimers from Gerbera piloselloides (L.) Cass.

Dibothrioclinin I and II, namely (+)-(11R,12S,25R,27S)- and (+/-)-(11RS,12RS,25RS,27SR)-3,3,7,17,21-pentamethyl-4,12,18,26-tetraoxaheptacyclo[15.11.1.0(2,15).0(5,14).0(6,11).0(19,28).0(20,25)]nonacosa-5(14),6,8,10,19(28),20,22,24-octaene-13,27-dione, respectively, are C(30)H(28)O(6) epimers which are derived from two bothrioclinin moieties joined so as to create an additional six-membered ring. Structurally, the epimers differ only by inversion at one C atom of a central ring junction and the corresponding six-membered rings have similar conformations in each molecule, except for one ring adjacent to this inversion site.

Asteraceae↗

PubMed2003

Crystal structure of a mini-intein reveals a conserved catalytic module involved in side chain cyclization of asparagine during protein splicing.

We have determined the crystal structure of a 154-residue intein derived from the dnaB gene of Synechocystis sp. strain PCC6803 and refined it to a 2.0-A resolution. The x-ray structure suggests that this intein possesses two catalytic sites that appear to be separately responsible for splicing and cleavage of the N- and C-terminal scissile bonds. The conserved intein block F residues are the important components of a catalytic site for side chain cyclization of the last intein residue, Asn-154. The data suggest that the imidazole ring of His-143 is involved in the activation of the side chain Ndelta atom of Asn-154, leading to a nucleophilic attack on the carbonyl carbon of Asn-154. Substitution of His-143 with Ala or Gln resulted in the inhibition of C-terminal cleavage. His-153, Asp-136, and a water molecule appear to constitute an oxyanion binding site by contacting the carbonyl oxygen of Asn-154 to stabilize the transition state. The structure and mutagenesis data also support that the close contact between the hydroxyl groups of Thr-138 and Ser-155, whose side chain participates in an S --> O acyl shift, plays an important role in the nucleophile orientation. Our structural modeling suggests that this catalytic module is conserved in the C-terminal subdomains of inteins from diverse organisms.

Amino Acid Sequence↗

PubMed2003

Nanoporous metals with controlled multimodal pore size distribution.

A simple two-step dealloying strategy is described to make free-standing metal membranes with hierarchical porous architecture. This structure has a bimodal pore size distribution composed of large porosity channels and small porosity channel walls, where each pore size can be tailored independently of the others. A new gas-phase electroless plating technique was also developed here that could be used to uniformly fill porous structures with pore size as small as 10 nm.

Journal Article↗

PubMed2003

Crystal structure of the ectodomain of human FcalphaRI.

Human FcalphaRI (CD89) is the receptor specific for IgA, an immunoglobulin that is abundant in mucosa and is also found in high concentrations in serum. Although FcalphaRI is an immunoglobulin Fc receptor (FcR), it differs in many ways from FcRs for other immunoglobulin classes. The genes of most FcRs are located on chromosome 1 at 1q21-23, whereas FcalphaRI is on chromosome 19, at 19q13.4, a region called the leukocyte receptor complex, because it is clustered with several leukocyte receptor families including killer cell inhibitory receptors (KIRs) and leukocyte Ig-like receptors (LIRs). The amino acid sequence of FcalphaRI shares only 20% homology with other FcRs but it has around 35% homology with its neighboring LIRs and KIRs. In this work, we analyzed the crystal structure of the ectodomain of FcalphaRI and examined structure similarities between FcalphaRI and KIR2DL1, KIR2DL2 and LIR-1. Our data show that FcalphaRI, KIRs, and LIRs share a common hydrophobic core in their interdomain interface, and FcalphaRI is evolutionally closer to LIR than KIR.

Amino Acid Sequence↗

PubMed2003

P202, an interferon-inducible protein, inhibits E2F1-mediated apoptosis in prostate cancer cells.

p202, an interferon (IFN) inducible protein, is a phosphonuclear protein involved in the regulation of cell cycle, apoptosis, and differentiation. E2F1 belongs to the E2F family of proteins that are important cell cycle regulators in promoting cell growth. On the other hand, the deregulated expression of E2F1 also triggers apoptosis independent of p53 status. It has been well documented that p202 is able to inhibit cell growth by binding to E2F1 and abolishing the E2F1-mediated transcriptional activation of S-phase genes. However, it is not known whether E2F1-mediated apoptosis can be counteracted by p202 expression. Here, we show that E2F1-mediated apoptosis induced by the infection of an E2F1-expressing adenoviral vector (Ad-E2F1) was greatly diminished in p202-expressing prostate cancer cells. The E2F1-mediated caspase-3 activation was also reduced in p202-expressing cells infected with Ad-E2F1. Since caspase-3 is one of the E2F1 transcriptional targets, this result is consistent with the ability of p202 to inhibit the transcriptional activity of E2F1. Therefore, our results suggest a possible link between the IFN and E2F pathways in regulating apoptosis.

Apoptosis↗

PubMed2003

Crystallization and preliminary X-ray crystallographic analysis of the trimer core from measles virus fusion protein.

Two heptad-repeat regions (HR1 and HR2) are highly conserved in paramyxovirus fusion proteins and form a stable helical trimer of heterodimers [(HR1-HR2)(3)] after the fusion between viral and cellular membranes. In this study, two HR regions of the fusion protein of measles virus, a member of the paramyxoviruses, were selected and overexpressed as a single chain (named 2-Helix) connected by an amino-acid linker using a GST-fusion expression system in Escherichia coli. Crystals of 2-Helix protein (GST removed) could be obtained from many conditions using the sitting- or hanging-drop vapour-diffusion method. A complete data set was collected in-house to 1.9 A resolution from a single crystal. The crystal belongs to space group P6, with unit-cell parameters a = b = 51.637, c = 67.058 A. To facilitate the crystal structure solution, SeMet-substituted 2-Helix crystals, grown under similar conditions to the native, were also obtained and diffracted X-rays to 1.8 A using synchrotron radiation.

Crystallization↗

PubMed2003

[Prevention of postoperative recurrence of human bladder carcinoma by intravesical instillation of immunotoxin, a clinical study].

OBJECTIVE: To observe the effects of intravesical instillation of immunotoxin (IT) on the prevention of recurrence of bladder carcinoma. METHODS: 128 patients with superficial bladder carcinoma or bladder carcinoma of T2 stage underwent operation, and then were randomly divided into 3 groups 2 - 3 weeks after operation to be instilled intravesically with solution of mitomycin (n = 53), Calmette-Guerin vaccine (n = 30), or IT (n = 45) once a week for 8 weeks and then once every month for 8 months respectively. Cystoscopy, blood routine examination, routine urine examination, and liver function test were conducted every 3 months. Immunohistochemistry was used to examine 30 samples of resected carcinoma. The effects and side effects were observed. Recurrence was verified by cystoscopy and/or ultrasonography, CT, and surgery. RESULTS: Out of the 30 samples of resected bladder carcinoma, 27 were staining positive (+ - + + +) with a positive rate of 90%. The binding activity was significantly different between the G(1) carcinoma of and the G(3) carcinoma (P < 0.05) and not significantly different between the G(1) and G(2) carcinomas and between the G(2) and G(3) carcinomas (both P > 0.05). The higher the grade of carcinoma, the stronger the binding activity of IT (P < 0.05). The recurrence rate in the first year were 11.1%, 10.0%, and 15.1% in the IT, BCG, and MMC groups respectively without significant difference between any 2 groups (all P > 0.05); and the recurrence rate in the 2nd year were 24.4%, 30.0%, and 28.3% in the 3 groups respectively without significant difference between any 2 groups (all P > 0.05). The side effect rate were 17.8% on the IT group, significantly lower than those in the other 2 groups (70.0% and 56.6% respectively, both P < 0.01). However, the side effect rates between the BCG group and MMC group was not significantly different (P > 0.05). CONCLUSION: IT is more effective on the prevention of recurrence of carcinomas with higher malignancy and has fewer side effects. The short-term effect of IT is similar to those of BCG and MMC. The activity of IT is associated with the grade and not the stage of carcinoma.

Administration, Intravesical↗

PubMed2003

Crystal structure of tabtoxin resistance protein complexed with acetyl coenzyme A reveals the mechanism for beta-lactam acetylation.

Tabtoxin resistance protein (TTR) is an enzyme that renders tabtoxin-producing pathogens, such as Pseudomonas syringae, tolerant to their own phytotoxins. Here, we report the crystal structure of TTR complexed with its natural cofactor, acetyl coenzyme A (AcCoA), to 1.55A resolution. The binary complex forms a characteristic "V" shape for substrate binding and contains the four motifs conserved in the GCN5-related N-acetyltransferase (GNAT) superfamily, which also includes the histone acetyltransferases (HATs). A single-step mechanism is proposed to explain the function of three conserved residues, Glu92, Asp130 and Tyr141, in catalyzing the acetyl group transfer to its substrate. We also report that TTR possesses HAT activity and suggest an evolutionary relationship between TTR and other GNAT members.

Acetyl Coenzyme A↗

PubMed2003

The crystal structure at 2A resolution of the Ca2+ -binding protein S100P.

S100P is a small calcium-binding protein of the S100 EF-hand-containing family of proteins. Elevated levels of its mRNA are reported to be associated with the progression to hormone independence and metastasis of prostate cancer and to be associated with loss of senescence in human breast epithelial cells in vitro. The first structure of human recombinant S100P in calcium-bound form is now reported at 2.0A resolution by X-ray diffraction. A flexible linker connects the two EF-hand motifs. The protein exists as a homodimer formed by non-covalent interactions between large hydrophobic areas on monomeric S100P. Experiments with an optical biosensor to study binding parameters of the S100P monomer interaction showed that the association rate constant was faster in the presence of calcium than in their absence, whereas the dissociation rate constant was independent of calcium. The K(d) values were 64(+/-24)nM and 2.5(+/-0.8) microM in the presence and in the absence of calcium ions, respectively. Dimerization of S100P is demonstrated in vivo using the yeast two-hybrid system. The effect of mutation of specific amino acids suggests that dimerization in vivo can be affected by amino acids on the dimer interface and in the hydrophobic core.

Amino Acid Sequence↗