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Biomedical subjects

Y Wei

Publications and source records attributed to Y Wei.

At least 253 records · Page 14Linked to original sources
PubMed1997

[Comparison of bioavailability between nimotop and nimodipine tablet].

A new analytical method was established for determining plasma level of nimodipine using HPLC and its application to determine the bioavailability of nimodipine. Experiments were performed on a Waters Model Baseline 810 System instrument. A 3.9 mm x 200 mm stainless steel column was packed with YWG-C18(10 microns) as the stationary phase. The mobile phase was a mixture solution of methanol--water (60/40, v/v) with 1.00 ml.min-1 at 35 degrees C. The detector was set at 358 nm. The plasma samples were extracted with ether--n-hexane (1:1). Calibration curve was linear (gamma = 0.9999) in the concentration range of 5-300 ng.ml-1. The within-day and between-day precision (RSD) were less than 3% and 5%, respectively, with average recoveries of 97.67%-102.3%. The study on bioavailability of numodipine between tablet A (made in China) and nimotop (Bayer, Germany) was carried out in 8 volunteers at the oral dose of 120 mg by cross-over method. Two-compartment open model was suitable for describing the disposition of nimodipine. The main pharmacokinetic parameters were shown in Tab 1 and mean plasma concentration--time curve of nimodipine was shown in Fig 1. The results indicate that tablet A exhibited a lower bioavailability (relative to nimotop). We suggest that the product tablet A must be improved in formula and technology.

Adult↗
PubMed1997

[Herbalogical studies of the medicinal plants on Rubus].

This paper deals with the investigation of the medicinal plants of Rubus recorded in the herbalogical works of the past dynasties. The substitutes and false drug of Fu Penzi are also investigated. The result show that Fu Penzi recorded in Materia Medica shall be R. coreanus, and Pong Le be R. lambertianus in modern times.

History, 15th Century↗
PubMed1997

[Investigation of alpha-amylase denatured by urea and guanidine hydrochloride. I. Studies on denaturation mechanism and renaturation efficiency by high-performance hydrophobic interaction chromatography].

The varieties of alpha-amylase denatured with 8.0 mol/L urea and 7.0 mol/L guanidine hydrochloride (GuHCl) solutions and their refolded intermediates were separated and renatured through high performance hydrophobic interaction chromatography (HPHIC). With investigating and comparing the numbers of the refolded intermediates and the bioactivity recovery of renaturation by means of HPHIC, it was found that these are quite different. The results can be attributed to the different denaturation mechanism of alpha-amylase with the two denaturing agents. The numbers of the refolded intermediates of urea-unfolded alpha-amylase were found to be more than that denatured by GuHCl, because GuHCl may make the changes in the surface of alpha-amylase molecules, by contrast, urea may do the changes not only in the surface of the protein, but also in the hydrophobic packet interior of the molecules. The HPHIC packings with weak hydrophobicity was found to have good separation efficiency and to have almost continuous and many peaks denoting these intermediates, while that with strong hydrophobicity was found to have higher bioactivity recovery. The numbers of the intermediates of urea-unfolded alpha-amylase were much more than that of bovine pancreatic trypsin inhibitor (BPTI) separated by Weissman et al. The effect of temperature on the separations and the renaturations were investigated too. The result showed that the higher the column temperature, the more the refolded intermediates of unfolded alpha-amylase separated and the lower bioactivity recovery were obtained from HPHIC.

Animals↗
PubMed1997

[Quantitative determination of the nickel, tin, copper, scandium, zirconium and hafnium in silicate sample by laser microspectrochemical analysis].

Quantitative determination of the nickel, tin, copper, scandium, zirconium and hafnium in silicate sample were carried out by laser microspectrochemical analysis, results show that the method has good precision and accuracy. The stability of the laser output and the selection of auxiliary spark excitation condition in experimental process were discussed.

English Abstract↗
PubMed1997

[The determination of high content tin in powder samples by line width method].

The quantitative determination of 60% Sn in tantalum-tin mineral samples was carried out by line width method. When the concentrations of internal standard element Pb in all three standard series was 1%, 2%, and 3% respectively,the influence of Pb to the analytical results was discussed. The experimental results show that the different contents of the internal standard are different for both the accuracy and precision of spectral analysis.

English Abstract↗
PubMed1997

[Some YAC contig construction and long range physical mapping at human X chromosome Xp11.3-21.3].

Human X chromosome short arm Xp11.3-p21.3 is an area, where several genetic disease gene loci are located. In this work, the YAC conting construction, long range physical mapping were done for this region. Some DNA probes and STS markers were used for YAC screening. Totally 77 YACs were obtained from the YAC libraries of CEPH, ICRF and ours. The size determination, 26 pairs of microsatelite STS analysis, single copy probe hybridization, Alu-PCR finger printing and long range physical mapping were conducted with these YACs. These results allowed us to map these YACs, and finally 6 YAC contigs were obtained in Xp11.3-21.3, covering about 15.3 Mb. This work will greatly facilitate the positional cloning of disease genes or the genome sequencing in this important region.

Chromosome Mapping↗
PubMed1997

[Studies on the phenotypic differences of P68 RNA helicases in four cell lines].

The dynamic changes of P68 RNA helicases derived from four cell lines were compared on the level of proteins and mRNAs. Of the four cell lines, HeLa and TC3H10 are tumouric while NIH 3T3 and NC3H10 are nontumouric. The TC3H10 is the derivative of NC3H10 induced by 3H-TdR. The growing curves showed that all of them can reach Logarithum phase around 24 hours post-inoculation. The Western blotting showed that the P68 RNA helicases in cells exhibited some regular patterns along with the extended growth of the cell cultures: they appeared as early as 6 hours post-inoculation, reached to the top about 24 hours, and dropped and maintained to low level after then. During a whole passage the bands of P68 RNA helicases were only single in tumour cells but multiple in nontumour cells with moderate changes. RNA slot hybridization resulted in similar quantitative patterns of P68 mRNAs and its proteins in each line. The ATPase activities of P68 RNA helicases purified by McAb-PAb 204 mediated immunoprecipitation were ssRNA-dependent, consistent with the results of P68 RNA helicases reported by others. These results first showed the close relationship between P68 RNA helicase and cell growth on the molecular level, and maybe implied its potential functions in the cell transformation process.

3T3 Cells↗
PubMed1997

[Endometrial cytology in normal postmenopausal women and during hormone replacement therapy].

OBJECTIVE: To explore the possibility of endometrial cyopathologic examination as a method of monitoring endometrium during hormone replacement therapy (HRT) in postmenopausal women. METHODS: Endometrial cells were taken via tubal aspiration in 60 normal postmenopausal women (non-HRT group) and 41 with HRT for 3-18 months (HRT group). Their morphologic changes were observed and compared by cytopathologist. RESULTS: Atrophic endometrium was found in 51.7% of the non-HRT group. Its proportion increased with age and the time after menopause. Macrophages were seen in 68.3% of this group. However, in the HRT group the occurrence of atrophic type and macrophage (12.2%, 7.0% respectively) was significantly lower than that in the non HRT group (P < 0.05). Heterogeneity of endometrial cell type was shown both in non-HRT (38.3%) and HRT (65.8%) groups. CONCLUSIONS: Endometrial cells of postmenopausal women are not always atrophic in appearance. They change significantly during HRT. Endometrial cytological examination may be useful for monitoring during HRT.

Endometrium↗
PubMed1996

Efficient interaction of HIV-1 with purified dendritic cells via multiple chemokine coreceptors.

HIV-1 actively replicates in dendritic cell (DC)-T cell cocultures, but it has been difficult to demonstrate substantial infection of purified mature DCs. We now find that HIV-1 begins reverse transcription much more efficiently in DCs than T cells, even though T cells have higher levels of CD4 and gp120 binding. DCs isolated from skin or from blood precursors behave similarly. Several M-tropic strains and the T-tropic strain IIIB enter DCs efficiently, as assessed by the progressive formation of the early products of reverse transcription after a 90-min virus pulse at 37 degrees C. However, few late gag-containing sequences are detected, so that active viral replication does not occur. The formation of these early transcripts seems to follow entry of HIV-1, rather than binding of virions that contain viral DNA. Early transcripts are scarce if DCs are exposed to virus on ice for 4 h, or for 90 min at 37 degrees C, conditions which allow virus binding. Also the early transcripts once formed are insensitive to trypsin. The entry of a M-tropic isolates is blocked by the chemokine RANTES, and the entry of IIIB by SDF-1. RANTES interacts with CCR5 and SDF-1 with CXCR4 receptors. Entry of M-tropic but not T-tropic virus is ablated in DCs from individuals who lack a functional CCR5 receptor. DCs express more CCR5 and CXCR4 mRNA than T cells. Therefore, while HIV-1 does not replicate efficiently in mature DCs, viral entry can be active and can be blocked by chemokines that act on known receptors for M- and T-tropic virus.

Cells, Cultured↗
PubMed1996

Crystallization of a novel esterase which inactivates the macrolide toxin brefeldin A.

A novel esterase obtained from Bacillus subtilis and capable of hydrolyzing the phytotoxin brefeldin A was crystallized using the hanging-drop technique. The crystals have two forms and both are monoclinic: form I, space group P2(1) with a = 101.7, b = 64.1, c = 55.4 A and beta = 102.5 degrees, and form II, space group C2 with a = 140.7, b = 82.6, c = 81.5 A and beta = 112.5 degrees. There are two molecules related by a pronounced non-crystallographic dyad per asymmetric unit in both crystal forms. The crystals diffract to 2.3 A using a rotating-anode X-ray source.

Journal Article↗
PubMed1996

Mac-1 (CD11b/CD18) and the urokinase receptor (CD87) form a functional unit on monocytic cells.

The leukocyte integrin Mac-1 (CD11b/CD18) and the urokinase receptor (uPAR, CD87) mediate complementary functions in myelomonocytic cells. Both receptors promote degradation of fibrin(ogen) and also confer adhesive properties on cells because Mac-1 and uPAR bind fibrin and vitronectin, respectively. Staining of lung biopsy specimens from patients with acute lung injury indicated that fibrin and vitronectin colocalize at exudative sites in which macrophages bearing these receptors accumulate. Because of the parallel roles and physical proximity of Mac-1 and uPAR, the capacity of these receptors to functionally interact was explored. Induction of Mac-1 and uPAR expression on monocytic cell lines by transforming growth factor- beta 1 and 1.25-(OH)2 vitamin D3 conferred urokinase and uPAR-dependent adhesion to vitronectin, which was further promoted by engagement of Mac-1. Vitronectin attachment promoted subsequent Mac-1-mediated fibrinogen degradation threefold to fourfold. In contrast, enhancement of uPAR occupancy by exogenous urokinase or receptor binding fragments thereof inhibited Mac-1 function. Addition of urokinase progressively inhibited Mac-1-mediated fibrinogen binding and degradation (maximal inhibition, 91% +/- 14% and 72% +/- 15%, respectively). Saturation of uPAR with urokinase also inhibited binding of the procoagulant Mac-1 ligand, Factor X. These inhibitory effects of uPAR were reproduced in fresh monocytes, cultured monocytic cells, and in Chinese hamster ovary (CHO) cells transfected with both human Mac-1 and human uPAR. These data show that the procoagulant and fibrinolytic potential of monocytic cells is co-ordinately regulated by ligand binding to both Mac-1 and uPAR and identify uPAR as a regulator of integrin function. Vitronectin-enhanced fibrin(ogen) turnover by Mac-1 may operate as a salvage pathway in the setting of urokinase and plasmin inhibitors to promote clearance of the provisional matrix and subsequent healing.

Animals↗
PubMed1996

Calmodulin binds to and inhibits GTP binding of the ras-like GTPase Kir/Gem.

Recently, a new subfamily of Ras-related GTP-binding proteins consisting of Rad (Ras associated with diabetes), Gem (immediate early gene expressed in mitogen-stimulated T-cells), and Kir (tyrosine kinase-inducible Ras-like) was discovered. The C terminus of these proteins contains an extension of approximately 30 amino acids not present in other members of the Ras family and which exhibits all the hallmarks typical for calmodulin (CaM)-binding domains. A peptide corresponding to the putative CaM-binding domain of the Kir/Gem protein was synthesized, and its affinity for CaM was determined by fluorescence spectrometry. Titration of dansyl-CaM with the Kir/Gem peptide gave an affinity constant of 1 nM. Furthermore, a single point mutation of the peptide, W269G, abolished this high affinity interaction. Gel-shift analysis showed that the complex formation between CaM and the Kir/Gem peptide is strictly calcium-dependent. We also demonstrate with a newly developed [32P]CaM overlay technique that full-length Kir/Gem and Rad proteins bind CaM in a Ca2+-dependent fashion. The binding of CaM to glutathione S-transferase-Kir and GST-Gem inhibited the binding of GTP to Kir/Gem significantly. These results suggest the existence of a direct link between Ca2+/CaM and growth factor signal transduction pathways at the level of small Ras-like GTPases.

Amino Acid Sequence↗
PubMed1996

Regulation of integrin function by the urokinase receptor.

Integrin function is central to inflammation, immunity, and tumor progression. The urokinase-type plasminogen activator receptor (uPAR) and integrins formed stable complexes that both inhibited native integrin adhesive function and promoted adhesion to vitronectin via a ligand binding site on uPAR. Interaction of soluble uPAR with the active conformer of integrins mimicked the inhibitory effects of membrane uPAR. Both uPAR-mediated adhesion and altered integrin function were blocked by a peptide that bound to uPAR and disrupted complexes. These data provide a paradigm for regulation of integrins in which a nonintegrin membrane receptor interacts with and modifies the function of activated integrins.

Amino Acid Sequence↗
PubMed1996

Activation of N-myc2 gene expression by cis-acting elements of oncogenic hepadnaviral genomes: key role of enhancer II.

Woodchuck hepatitis virus (WHV) is strongly oncogenic in its native host, producing hepatocellular carcinomas in the majority of chronically infected animals. An important step in this oncogenic process is the activation of N-myc transcription in the liver as a result of integration of viral sequences in cis to the N-myc2 locus. We have examined the viral sequences involved in the up-regulation of N-myc2 using transient transfection assays of permissive HepG2 cells in culture. WHV sequences corresponding to enhancer I of human hepatitis B virus are nearly inactive in N-myc2 activation when tested alone and are not significantly activated by WHV X gene coexpression. By contrast, sequences corresponding to enhancer II strongly activate expression in a position and orientation-independent manner and are only modestly further up-regulated by WHx expression. Qualitatively similar results were observed with sequences of the ground squirrel hepatitis virus (GSHV), which produces hepatomas in woodchucks without insertional activation of N-myc2, but the GSHV EnII element is fourfold less active in N-myc2 up-regulation than its WHV counterpart.

Cloning, Molecular↗
PubMed1996

Induction of autologous tumor killing by heat treatment of fresh human tumor cells: involvement of gamma delta T cells and heat shock protein 70.

Autologous tumor killing (ATK) has been implicated as an important prognostic factor in cancer patients since the ability of blood lymphocytes to kill freshly isolated autologous tumor cells was strongly associated with good prognosis of the patients. The present study was designed to induce or enhance ATK sensitivity of fresh human tumor cells by heat stress. Brief exposure of fresh human tumor cells to elevated temperature increased their susceptibility to lysis by autologous blood lymphocytes in a short-term (51)Cr release assay. In addition, the heat-elevated ATK sensitivity was confirmed by clonogenic assays. An increase in ATK was observed with unstimulated lymphocytes in 42% of the cases and OK432 (streptococcal preparation)-activated lymphocytes in 80% of the cases. Stimulation of blood lymphocytes with autologous, heat-stressed tumor cells and OK432 resulted in an increase in number of gamma delta T cells, which was associated with elevated ATK activity against the stressed tumor cells. At the clonal level, three gamma delta T-cell clones (V gamma 9/V delta 2+) proliferated in response to autologous, heat stressed tumor cells and/or OK432 and exhibited elevated cytotoxicity against the tumor cells. Western blot analysis revealed an increased expression of heat shock protein (HSP) 70 in heat- treated tumor cells. Some of them expressed HSP70 on their surfaces. The elevated cytoxicity against heat-stressed tumor cells was inhibited by treatment of targets with anti-HSP70 monoclonal antibody (mAb) or of effector cells with anti-V delta2 mAb. Reactivity of gamma delta T cells to autologous, heat- stressed tumor cells was also inhibited by anti-HSP70 mAb. These results indicate that exposure to heat of tumor cells induces ATK susceptibility, especially to OK432-activated effector cells, and suggest that gamma delta T cells may be involved in ATK against stressed tumor cells through recognition of HSP70 on the target cells.

Adult↗