[Study on GC fingerprint characteristic features of wuji baifeng pills].
In this paper, the fingerprint characteristic features that can be used for identification of Wuji Baifeng Pills were obtained by gas chromatographic analysis.
Alkanes↗
Biomedical subjects
Y Feng
Publications and source records attributed to Y Feng.
[Analysis of 12 cases of the intraosseous vascular malformation]
OBJECTIVE:This study is to discuss the main points of diagnosis and treatments of the intraosseous vascular malformations. METHODS: 12 cases have been compared and analyzed on the respects of the clinical and radiographic presentations and surgery methods. RESULTS: All the lesions were treated by radical resectins.Some of them also underwent the ligations of artery or transarterial embolizations. In two patients, vascularized bone graft with implants were carried out simultaneously. CONCLUSION: The results of this study indicate that the radiographys have no pathognomonic appearence. Surgery is widely accepted as a radical treatment at present. Nowadays, the main point is indicating to approach more on the functional restoration.
Journal Article↗
[Three-dimensional volumetric display--a new application of frequency up-conversion].
This paper discusses the present research situation and the application prospect of 3-D volumetric display technology. The possible usability and science significance of frequency up-conversion in 3-D volumetric display field are also demonstrated systematically. In ZBLAN: Pr, Yb glasses, we primarily demonstrated and achieved a new application of frequency up-conversion three dimensional volumetric display, using the two-frequency up-conversion of the rare earth ions. The efficiency of luminescence of Pr was enhanced much by the energy transfer between Pr and Yb ions.
English Abstract↗
[GFAAS determination of trace Cr(III) and Cr(VI) after its separation by coprecipitation-floatation with aluminium hydroxide].
A method for determination of trace Cr(III) in natural water and drinking water by GFAAS after separation by coprecipitation-floatation with Al(OH)3 has been studied. Cr(VI) was determined also after being reduced by FeSO4. Conditions of Cr(III) floatation such as pH, the amount of floatation agent and coprecipitator-Aluminium added, the flow rate of nitrogen gas, the floatation time etc. were discussed. The influence of coexisting elements was investigated. The detection limit is 0.027 microg/L (n = 15). For Cr(III) concentration level of 0.5 microg/L, the RSD is 3.4% and the recovery of Cr(III) is 96.0-104.0%.
Aluminum Hydroxide↗
[Indirect sensitized upconversion in Tm3+ and Yb3+ codoped non-crystal pentaphosphate].
We report the blue upconversion luminescence of Tm3+ and Yb3+ codoped non-crystal pentaphosphate pumped by -798nm laser diode. The samples were directly excited to 3F4 level of Tm3+ ion. Two energy transfer processes between Tm3+ and Yb3+ contribute mainly to the population of 1G4 level of Tm3+. Phonon plays an important role in the upconversion process.
English Abstract↗
A rapid and sensitive method for detection of urinary bladder tumors in rodents.
Explore the source record for details and available documents.
Animals↗
Evaluation of the role of specific acidic amino acid residues in electron transfer between the flavodoxin and cytochrome c3 from Desulfovibrio vulgaris.
A hypothetical model for electron transfer complex between cytochrome c3 and the flavodoxin from the sulfate-reducing bacteria Desulfovibrio vulgaris has been proposed, based on electrostatic potential field calculations and NMR data [Stewart, D. E., LeGall, J. , Moura, I., Moura, J. J. G., Peck, H. D., Jr., Xavier, A. V., Weiner, P. K., & Wampler, J. E. (1988) Biochemistry 27, 2444-2450]. This modeled complex relies primarily on the formation of five ion pairs between lysine residues of the cytochrome and acidic residues surrounding the flavin mononucleotide cofactor of the flavodoxin. In this study, the role of several acidic residues of the flavodoxin in the formation of this complex and in electron transfer between these two proteins was evaluated. A total of 17 flavodoxin mutants were studied in which 10 acidic amino acids--Asp62, Asp63, Glu66, Asp69, Asp70, Asp95, Glu99, Asp106, Asp127, and Asp129--had been permanently neutralized either individually or in various combinations by substitution with their amide amino acid equivalent (i.e., asparate to asparagine, glutamate to glutamine) through site-directed mutagenesis. The kinetic data for the transfer of electrons from reduced cytochrome c3 to the various flavodoxin mutants do not conform well to a simple bimolecular mechanism involving the formation of an intermediate electron transfer complex. Instead, a minimal electron transfer mechanism is proposed in which an initial complex is formed that is stabilized by intermolecular electrostatic interactions but is relatively inefficient in terms of electron transfer. This step is followed by a rate-limiting reorganization of that complex leading to efficient electron transfer. The apparent rate of this reorganization step was enhanced by the disruption of the initial electrostatic interactions through the neutralization of certain acidic amino acid residues leading to faster overall observed electron transfer rates at low ionic strengths. Of the five acidic residues involved in ion pairing in the modeled complex proposed by Stewart et al. (1988), the kinetic data strongly implicate Asp62, Glu66, and Asp95 in the formation of the electrostatic interactions that control electron transfer. Less certainty is provided by this study for the involvement of Asp69 and Asp129, although the data do not exclude their participation. It was not possible to determine whether the modeled complex represents the optimal configuration for electron transfer obtained after the reorganization step or actually represents the initial complex. The data do provide evidence for the importance of electrostatic interactions in electron transfer between these two proteins and for the existence of alternative binding modes involving acidic residues on the surface of the flavodoxin other than those proposed in that model.
Amino Acids, Dicarboxylic↗
The receptor binding site of human interleukin-3 defined by mutagenesis and molecular modeling.
Interleukin-3 (IL-3) is a member of the cytokine superfamily that promotes multi-potential hematopoietic cell growth by interacting with a cell surface receptor composed of alpha and beta chains. The newly available three-dimensional structure of a variant of human (h) IL-3 allowed us to evaluate new and existing mutagenesis data and to rationally interpret the structure-function relationship of hIL-3 on a structural basis. The amino acid residues that were identified to be important for hIL-3 activity are grouped into two classes. The first class consists of largely hydrophobic residues required for the structural integrity of the protein, including the residues in IL-3 that are largely conserved among 10 mammalian species. These residues form the core of a scaffold for the second class of more rapidly diverging solvent-exposed residues, likely to be required for interaction with the receptor. Ten important and solvent-exposed residues, Asp21, Gly42, Glu43, Gln45, Asp46, Met49, Arg94, Pro96, Phe113, and Lys116, map to one side of the protein and form a putative binding site for the alpha subunit of the receptor. A model of the IL-3.IL-3 receptor complex based on the human growth hormone (hGH).hGH soluble receptor complex structure suggests that the interface between IL-3 and the IL-3 receptor alpha subunit consists of a cluster of hydrophobic residues flanked by electrostatic interactions. Although the IL-3/IL-3 receptor beta subunit interface cannot be uniquely located due to the lack of sufficient experimental data, several residues of the beta subunit that may interact with Glu22 of IL-3 are proposed. The role of these residues can be tested in future mutagenesis studies to define the interaction between IL-3 and IL-3 receptor beta subunit.
Amino Acid Sequence↗
Collagen-based structures containing the peptoid residue N-isobutylglycine (Nleu): synthesis and biophysical studies of Gly-Nleu-Pro sequences by circular dichroism and optical rotation.
Single-chain peptide-peptoid structures, Ac-(Gly-Nleu-Pro)n-NH2 (n = 3, 6, and 10) and (Gly-Nleu-Pro)n-NH2 (n = 1 and 9), and template-assembled collagen analogs, KTA-[Gly-(Gly-Nleu-Pro)n-NH2]3 (n = 3 and 6; KTA represents cis,cis-1,3,5-trimethylcyclohexane-1,3, 5-tricarboxylic acid, also known as the Kemp triacid; Nleu denotes N-isobutylglycine), were prepared by solid-phase peptide synthesis methods. Biophysical studies using circular dichroism (CD) and optical rotation measurements show that these collagen analogs form triple-helical conformations when the chain is longer than a critical length. Unlike collagen-based structures composed of Gly-Pro-Hyp and Gly-Pro-Nleu sequences, results reveal that the presence of a positive CD peak between 220 and 225 nm is indicative of triple-helical conformations for these collagen-based structures composed of Gly-Nleu-Pro sequences. Results also indicate that the Gly-Nleu-Pro sequence possesses a higher triple-helical propensity than the Gly-Pro-Nleu sequence as demonstrated by the higher melting temperatures, the faster triple-helix folding, and the lower minimum concentration necessary to detect triple-helicity for the single-chain structures. Therefore, we conclude that the Nleu residue in the second position of the trimeric repeat is more effective in inducing triple-helix formation than Pro in the same position.
Amino Acid Sequence↗
Collagen-based structures containing the peptoid residue N-isobutylglycine (Nleu): conformational analysis of Gly-Nleu-Pro sequences by 1H-NMR and molecular modeling.
Molecular modeling and 1H-NMR were employed to study the structure and stability of collagen-like triple helices composed of Gly-Nleu-Pro repeats. The compounds studied include the acetyl analogs Ac-(Gly-Nleu-Pro)n-NH2 (where n = 1, 3, 6, and 10) and the KTA conjugates KTA-[Gly-(Gly-Nleu-Pro)n-NH2]3 (where n = 3 and 6 and KTA denotes the Kemp triacid). The presence of collagen-like assembled structures is supported by a consistent set of experimental observations, which include the appearance of a distinct set of resonances, low hydrogen-exchange rates for Gly NH, cooperative melting transition, and observation of several interchain NOEs. Using 1H-NMR, the triple helicity was monitored as a function of chain length, template, and temperature. These studies show that (Gly-Nleu-Pro)n sequences have a somewhat higher triple-helical propensity than (Gly-Pro-Nleu)n sequences. In addition, our investigations have shown that unlike the triple helices composed of Gly-Pro-Nleu repeats those composed of Gly-Nleu-Pro repeats can access conformations in which the Nleu side chains are arrayed between Pro residues belonging to different triple-helix cross sections. These structural features may serve as a basis for free energy computations and for the study of higher-order structures such as collagen-like fibrils containing peptoid moities.
Amino Acid Sequence↗
Novel anti-inflammatory compounds induce shedding of L-selectin and block primary capture of neutrophils under flow conditions.
Leumedins are small molecules that inhibit neutrophil movement into inflamed tissues. These compounds have been shown to inhibit the adherence of neutrophils in static adhesion assays mediated by beta2-integrins. We now report that leumedins, like activating agents, induce the loss of L-selectin from the neutrophil surface. The loss of L-selectin is unrelated to the inhibition of static adhesion, since neutrophils that have been pretreated with leumedins to cause shedding of L-selectin, followed by removal of drug, adhere normally in a static adhesion assay, and this adhesion is inhibited upon readdition of leumedin. In an assay of adhesion to endothelial cells under conditions of physiologic wall shear stress, leumedins prevent both primary capture of neutrophils mediated by L-selectin and firm adherence mediated by beta2-integrins.
Anti-Inflammatory Agents↗
Rodent models of the human acetylation polymorphism: comparisons of recombinant acetyltransferases.
The acetylation polymorphism is associated with differential susceptibility to drug toxicity and cancers related to aromatic and heterocyclic amine exposures. N-Acetylation is catalyzed by two cytosolic N-acetyltransferases (NAT1 and NAT2) which detoxify many carcinogenic aromatic amines. NAT1 and NAT2 also activate (via O-acetylation) the N-hydroxy metabolites of aromatic and heterocyclic amine carcinogens to electrophilic intermediates which form DNA adducts and initiate cancer. The classical N-acetylation polymorphism is regulated at the NAT2 locus, which segregates individuals into rapid, intermediate, and slow acetylator phenotypes. Some human epidemiological studies associate slow acetylator and rapid acetylator phenotypes with increased susceptibility to urinary bladder and colorectal cancers, respectively. The acetylation polymorphism has been characterized in three rodent species (mouse, Syrian hamster, and rat) to test associations between NAT2 acetylator phenotype and susceptibility to aromatic and heterocyclic amine-induced cancers in various tumor target organs. NAT1 and NAT2 from rapid and slow acetylator mouse, Syrian hamster, and rat each have been cloned and sequenced. Recombinant NAT1 and NAT2 enzymes enzymes encoded by these genes have been characterized with respect to their catalytic activities for both activation (O-acetylation) and deactivation (N-acetylation) of aromatic and heterocyclic amine carcinogens. The acetylation polymorphisms in mouse, Syrian hamster, and rat are herein reviewed and compared as models of the human acetylation polymorphism.
Acetylation↗
A comparison of structure-activity relationships between spermidine and spermine analogue antineoplastics.
A systematic investigation of the impact of spermidine analogues both in vitro and in vivo is described. The study characterizes the effects of these analogues on L1210 cell growth, polyamine pools, ornithine decarboxylase, S-adenosyl-L-methionine decarboxylase, spermidine/spermine N1-acetyltransferase, the maintenance of cellular charge, i.e., cationic equivalence associated with the polyamines and their analogues, and compares their ability to compete with spermidine for transport. The findings clearly demonstrate that the activity of the linear polyamine analogues is highly dependent on the length of the triamines and the size of the N(alpha),N(omega)-substituents. It appears that there is an optimum chain length for various activities and that the larger the N(alpha),N(omega)-alkyls, the less active the compound. Metabolic transformation including N-dealkylation of these compounds is also evaluated. While there is no monotonic relationship between chain length and the ability of the analogue to be metabolized, the dipropyl triamines are clearly more actively catabolized than the corresponding methyl and ethyl systems. A comparison of the triamines with the corresponding tetraamines is made throughout the text regarding both in vitro activity against L1210 cells and in vivo toxicity measurements, suggesting that several triamine analogues may offer therapeutic advantages over the corresponding tetraamines.
Acetyltransferases↗
Determination of agmatine in brain and plasma using high-performance liquid chromatography with fluorescence detection.
Decarboxylated arginine, agmatine, is a neurotransmitter candidate for imidazoline receptors. A method is described to measure agmatine in rat brain and human plasma by isocratic high-performance liquid chromatography (HPLC) with fluorescence detection and o-phthalaldehyde derivatization. Quantitation is based on the method of additions of internal agmatine spikes. This assay has sensitivity in the low picomole range and a detection limit of 100 fmol. The correlation coefficient for the agmatine standard curve was 0.999+/-0.001 S.D., and intra- and inter-assay C.V.s were less than 8%. The accuracy of our isocratic method compared favorably with a gradient HPLC protocol, originally developed for bacterial agmatine, which we modified for use with tissues. Agmatine concentrations in rat brain were proportioned similarly to the regional distribution of imidazoline-1 receptors. These methods can be used as reliable research tools in various biological samples.
Adult↗
Differential regulation of HIV-1 fusion cofactor expression by CD28 costimulation of CD4+ T cells.
Activation of CD4(+) T lymphocytes from human immunodeficiency virus-type 1 (HIV-1)-infected donors with immobilized antibodies to CD3 and CD28 induces a virus-resistant state. This effect is specific for macrophage-tropic HIV-1. Transcripts encoding CXCR4/Fusin, the fusion cofactor used by T cell line-tropic isolates, were abundant in CD3/CD28-stimulated cells, but transcripts encoding CCR5, the fusion cofactor used by macrophage-tropic viruses, were not detectable. Thus, CD3/CD28 costimulation induces an HIV-1-resistant phenotype similar to that seen in some highly exposed and HIV-uninfected individuals.
Antibodies, Monoclonal↗
Fragile X mental retardation protein: nucleocytoplasmic shuttling and association with somatodendritic ribosomes.
Fragile X syndrome, a leading cause of inherited mental retardation, is attributable to the unstable expansion of a CGG-repeat within the FMR1 gene that results in the absence of the encoded protein. The fragile X mental retardation protein (FMRP) is a ribosome-associated RNA-binding protein of uncertain function that contains nuclear localization and export signals. We show here detailed cellular localization studies using both biochemical and immunocytochemical approaches. FMRP was highly expressed in neurons but not glia throughout the rat brain, as detected by light microscopy. Although certain structures, such as hippocampus, revealed a strong signal, the regional variation in staining intensity appeared to be related to neuron size and density. In human cell lines and mouse brain, FMRP co-fractionated primarily with polysomes and rough endoplasmic reticulum. Ultrastructural studies in rat brain revealed high levels of FMRP immunoreactivity in neuronal perikarya, where it is concentrated in regions rich in ribosomes, particularly near or between rough endoplasmic reticulum cisternae. Immunogold studies also provided evidence of nucleocytoplasmic shuttling of FMRP, which was localized in neuronal nucleoplasm and within nuclear pores. Moreover, labeling was observed in large- and small-caliber dendrites, in dendritic branch points, at the origins of spine necks, and in spine heads, all known locations of neuronal polysomes. Dendritic localization, which was confirmed by co-fractionation of FMRP with synaptosomal ribosomes, suggests a possible role of FMRP in the translation of proteins involved in dendritic structure or function and relevant for the mental retardation occurring in fragile X syndrome.
Animals↗
Partial characterization of the MPM-2 phosphoepitope.
The MPM-2 monoclonal antibody recognizes a distinctive group of proteins that are associated with structural components of the mitotic apparatus. These proteins become phosphorylated and MPM-2 reactive during M-phase and appear to be required for both the onset and completion of M-phase. Based upon the analysis of reported MPM-2 reactive sequences, we have developed a model for the essential elements that comprise the MPM-2 epitope. This model was tested by employing a series of synthetic phosphopeptides. We show here that a 14 amino acid synthetic phosphopeptide, derived from a potential MPM-2 site on human DNA topoisomerase II, is recognized by the MPM-2 antibody. This phosphopeptide was sufficient to compete for MPM-2 antibody recognition of (1) an isolated native mitotic MPM-2 antigen on dot blots, (2) proteins on immunoblots of mitotic cell lysates, and (3) specific immunostaining of mitotic cells. These results indicated that the topoisomerase peptide contained all of the essential elements of the MPM-2 epitope. By substituting selected amino acids with alanine, we were able to examine the contribution of different amino acids to the binding between the MPM-2 antibody and the epitope. Changing the amino acid that was adjacent to the phosphorylated threonine residue on the C-terminal side (the +1 position) had no effect on MPM-2 antibody binding. However, substitution of aromatic amino acids at either the -2 or +2 positions reduced antibody recognition. The aromatic amino acid at the -2 position appeared to be the most critical residue of those tested that influenced antibody binding. These results provide information required for the molecular definition of the MPM-2 epitope and should aid in the identification of potential MPM-2 reactive sites on other mitotic phosphoproteins.
Amino Acid Sequence↗
Cloning of a novel member of the G protein-coupled receptor family related to peptide receptors.
We have used PCR with degenerate oligonucleotide primers to clone novel members of the G protein-coupled receptor (GPCR) superfamily. We report here a novel gene, CEPR, which encodes a candidate receptor that is most similar to the peptide receptor family. The coding region of the human CEPR gene predicts a seven transmembrane domain (TM) receptor of 375 amino acids. CEPR has 28-30 percent amino acid identity to angiotensin II and interleukin 8 receptors, and slightly lower percent identity to many other GPCRs. Northern blot analysis reveals a 3.3 kb CEPR transcript in different regions of human brain and in various peripheral tissues. The ubiquitous tissue distribution of CEPR, its expression in early development, and its conservation in evolution indicate a potentially important biological function for this receptor and its putative peptide ligand.
Amino Acid Sequence↗