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Biomedical subjects

W Wei

Publications and source records attributed to W Wei.

At least 145 records · Page 8Linked to original sources
PubMed1997

Bypass of senescence after disruption of p21CIP1/WAF1 gene in normal diploid human fibroblasts.

Most somatic cells die after a finite number of cell divisions, a phenomenon described as senescence. The p21(CIP1/WAF1) gene encodes an inhibitor of cyclin-dependent kinases. Inactivation of p21 by two sequential rounds of targeted homologous recombination was sufficient to bypass senescence in normal diploid human fibroblasts. At the checkpoint between the prereplicative phase of growth and the phase of chromosome replication, cells lacking p21 failed to arrest the cell cycle in response to DNA damage, but their apoptotic response and genomic stability were unaltered. These results establish the feasibility of using gene targeting for genetic studies of normal human cells.

Apoptosis↗
PubMed1997

Studies of Ternary Surface Complexes at Liquid-Solid Interfaces in Seawater

The E (%)-pH curves of the ternary surface complexes at liquid-solid interfaces in the simulated seawater system of alpha-FeOOH-Cu(II)-tryptophan were determined. The diffuse reflectance IR spectra of the species at the solid surfaces in the above ternary equilibration system were examined. The above two results were comparatively studied. It is shown that the coadsorption of Cu(II) and tryptophan on alpha-FeOOH surface results in the formation of the ternary surface complex. Cu(II) can promote the exchange adsorption of tryptophan on alpha-FeOOH surface. The diffuse reflectance IR spectra can give us some evidence for the structure of the ternary surface complex, and these results are in accordance with the results of the E (%)-pH curves.

Journal Article↗
PubMed1997

BRCA1 is a component of the RNA polymerase II holoenzyme.

The familial breast-ovarian tumor suppressor gene product BRCA1 was found to be a component of the RNA polymerase II holoenzyme by several criteria. BRCA1 was found to copurify with the holoenzyme over multiple chromatographic steps. Other tested transcription activators that could potentially contact the holoenzyme were not stably associated with the holoenzyme as determined by copurification. Antibody specific for the holoenzyme component hSRB7 specifically purifies BRCA1. Immunopurification of BRCA1 complexes also specifically purifies transcriptionally active RNA polymerase II and transcription factors TFIIF, TFIIE, and TFIIH. Moreover, a BRCA1 domain, which is deleted in about 90% of clinically relevant mutations, participates in binding to the holoenzyme complex in cells. These data are consistent with recent data identifying transcription activation domains in the BRCA1 protein and link the BRCA1 tumor suppressor protein with the transcription process as a holoenzyme-bound protein.

BRCA1 Protein↗
PubMed1997

Hrp pilus: an hrp-dependent bacterial surface appendage produced by Pseudomonas syringae pv. tomato DC3000.

Hypersensitive response and pathogenicity (hrp) genes control the ability of major groups of plant pathogenic bacteria to elicit the hypersensitive response (HR) in resistant plants and to cause disease in susceptible plants. A number of Hrp proteins share significant similarities with components of the type III secretion apparatus and flagellar assembly apparatus in animal pathogenic bacteria. Here we report that Pseudomonas syringae pv. tomato strain DC3000 (race 0) produces a filamentous surface appendage (Hrp pilus) of 6-8 nm in diameter in a solid minimal medium that induces hrp genes. Formation of the Hrp pilus is dependent on at least two hrp genes, hrpS and hrpH (recently renamed hrcC), which are involved in gene regulation and protein secretion, respectively. Our finding of the Hrp pilus, together with recent reports of Salmonella typhimurium surface appendages that are involved in bacterial invasion into the animal cell and of the Agrobacterium tumefaciens virB-dependent pilus that is involved in the transfer of T-DNA into plant cells, suggests that surface appendage formation is a common feature of animal and plant pathogenic bacteria in the infection of eukaryotic cells. Furthermore, we have identified HrpA as a major structural protein of the Hrp pilus. Finally, we show that a nonpolar hrpA mutant of P. syringae pv. tomato DC3000 is unable to form the Hrp pilus or to cause either an HR or disease in plants.

Bacterial Proteins↗
PubMed1997

Redistribution of platelet membrane glycoprotein IV and release of intracellular alpha-granule thrombospondin in patients with chronic myelogenous leukemia.

The redistribution of platelet membrane glycoprotein IV (GPIV) and the release of intracellular alpha-granule thrombospondin (TSP) were examined and the inhibition of beta-thromboglobulin (beta-TG) and platelet factor 4 (PF4) in patients with chronic myelogenous leukemia (CML) was observed and quantitation of beta-TG and PF4 in sera was conducted. GPIV in inactive platelet from CML was 36080 +/- 17010 molecules/platelet as compared with 13190 +/- 4810 from the controls (P < 0.01). No abnormality was found in the distribution of platelet membrane GPIb and GPIIb/IIIa (P > 0.05). The GPIV redistribution on active platelet membrane induced thrombin (IU/ml) from CML and healthy donors was 44320 +/- 32310 and 22800 +/- 12700 molecules/platelet respectively (P < 0.01). The difference in the release of intracellular alpha-granule TSP between CML and the control group was not found (P > 0.05). There was no direct correlation between GPIV expression and TSP binding after platelet activation. The high levels of beta-TG and PF4 in sera inhibited release of intracellular alpha-granule TSP in vitro. These results indicate that the abnormality of platelet membrane GPIV is a common marker in CML, therefore the specific increase of platelet GPIV in patients with CML may be a useful tool for the diagnosis and monitoring of the platelet dysfunction. The release of internal TSP pools is hindered by either beta-TG or PF4 in sera.

CD36 Antigens↗
PubMed1997

The effect of levobunolol hydrochloride on the calcium and potassium channels in isolated ventricular myocytes of guinea pig.

The effects of levobunolol hydrochlorid (Bun) on the type L calcium channel currents (ICA) and delayed rectifier potassium channel currents (IK) in isolated ventricular myocytes of guinea pig were studied by using patch clamp whole cell recording techniques. The results were showed that: 1) Bun caused a dose dependent decrease in ICA and a dose-dependent increase in IK of the ventricular myocytes. The threshold concentrations of Bun for ICA and IK were 10(-8) mol/L and 10(-7) mol/L respectively. The maximum effective concentration of Bun for bot ICA and IK was 3x10(-5) mol/L, and half-maximal concentration was 3x10(-6) mol/L; 2) IK was blocked by 2x100(-6) mol/L tetraethylammonium (TEA). A concentration of 3x10(-6) mol/L Bun showed a decreasing effect on the ICA as revealed by the current-voltage relationship curve, i.e., Bun caused an elevation of the curve;3) When ICA was blocked by 2x10(-6) mol/L Isoptin (Verapamil), at a concentration of 3x10(-6) mol/L Bun showed an increasing effect on IK and the effect could be blocked by TEA. The above-mentioned results indicated that Bun had an inhibitory effect on ICA and a fascilitatory effect on IK. The results suggested that the molecular mechanisms of antihypertensive, heart rate slowing the beta -receptor blocking effects of Bun might be due to decrease of ICA and increase of IK.

Adrenergic beta-Antagonists↗
PubMed1997

A novel nucleic acid helicase gene identified by promoter trapping in Arabidopsis.

A gene encoding a predicted nucleic acid helicase was identified in Arabidopsis thaliana by activation of a promoter trap. An in vivo transcriptional fusion between the helicase gene and a promoterless uidA (gusA) gene was generated, which was expressed specifically in the tapetum and vascular tissues. The tagged gene, designated HVT1 (Helicase in Vascular tissue and Tapetum), encodes a native transcript of approximately 4.4 kb, which is of very low abundance. The predicted HVT1 protein, of 1291 amino acid residues, is homologous to the Drosophila MALELESS, human RNA helicase A and bovine nuclear DNA helicase proteins, and represents the first identified member of a new subgroup within the mle group of the DEAH family. Low stringency genomic Southern blot analysis indicates that at least two structurally related genes exist in Arabidopsis. We suggest that the HVT1 protein may play a role in nucleic acid unwinding in restricted cell types during both vegetative and reproductive phases of the Arabidopsis life cycle.

Amino Acid Sequence↗
PubMed1997

Lck regulates Vav activation of members of the Rho family of GTPases.

Vav is a member of a family of oncogene proteins that share an approximately 250-amino-acid motif called a Dbl homology domain. Paradoxically, Dbl itself and other proteins containing a Dbl domain catalyze GTP-GDP exchange for Rho family proteins, whereas Vav has been reported to catalyze GTP-GDP exchange for Ras proteins. We present Saccharomyces cerevisiae genetic data, in vitro biochemical data, and animal cell biological data indicating that Vav is a guanine nucleotide exchange factor for Rho-related proteins, but in similar genetic and biochemical experiments we fail to find evidence that Vav is a guanine nucleotide exchange factor for Ras. Further, we present data indicating that the Lck kinase activates the guanine nucleotide exchange factor and transforming activity of Vav.

Animals↗
PubMed1997

Treatment of biliary atresia by portoenterostomy and liver transplantation: The Queen Mary Hospital, Hong Kong experience.

Ninety three out of 96 patients with biliary atresia (BA) underwent Kasai 1 portoenterostomy and 11 children subsequently underwent 12 liver transplantation (LTX) procedures which included 8 living related liver transplants (LRLT), 3 reduced-size liver transplants (RSLT) and 1 orthotopic liver transplantation (OLT). During a follow-up period of 3-206 months (mean, 73 months) after portoenterostomy and 3-63 months after LTX, 50% of 96 patients are alive and well with total clearance of jaundice while 12% are mildly jaundiced, 10% are deeply jaundiced and 28% have died. Two of the 3 patients who did not undergo portoenterostomy and 25 from the portoenterostomy group have died. Of the latter group, 22 deaths occurred before, and 3 after the introduction of LTX therapy respectively. Of the 68 long-term survivors, 32 are less than 5, and 36 are 6-17 years old. Complete clearance of jaundice was achieved in 55% of patients irrespective of whether portoenterostomy was initially performed at < 10 or between 10 and 12 weeks. Portoenterostomy performed beyond 13 weeks was associated with declining results. We conclude that (1) portoenterostomy combined with liver transplantation, when indicated, has given patients with BA a much better prognosis and (2) pediatric LTX in our institute is a well established procedure with 100% patient and 88% primary graft survival.

Age Factors↗
PubMed1997

[Prognostic factors of cervical lymph metastases from squamous cell carcinomas the head and neck].

Cervical lymph node prognostic factors were investigated in 382 head and neck squamous cell carcinoma (SCC) patients including oral cavity cancer, oropharngeal cancer, hypopharyngeal cancer and laryngeal cancer. The overall five year survival rate of these patients was 46.1%, and the 5 year survival rate was 49.7%, 39.7%, 35.0% and 60.3% in carcinomas of oral cavity, oropharynx, hypopharynx and larynx, respectively. It was confirmed that clinical N staging, the size of lymph nodes, pathological conditions of neck nodes, numbers of positive areas and the lowest level of invasion are of prognostic value. Some suitable measures must be taken to cope with these factors to improve the five-year survival rate of patients with SCC of the head and neck.

Adult↗
PubMed1997

[The diversity of human hematopoietic stem/progenitor cells: VIII. Sterological features of CD 34+ hematopoietic cells isolated from human bone marrow].

Human CD 34+ hematopoietic cells, a distinctive cell population containing hematopoietic stem/progenitor cells, have the capability to highly self-renewal, differentiation into all lineages of committed progenitor cells and reconstitution of both long-term hematopoiesis and immune functions after transplantation. In our previous study, the morphological, ultrastructural and cytochemical features concerning CD 34+ hematopoietic cells obtained by a two-step isolated systems of CIMS-100/FACS 440 with 100% purity were depicted. Based on these observations on CD 34+ hematopoietic cells under light microscope, SEM and TEM, we recently analyze the sterological features of CD 34+ hematopoietic cells with the aid of Quantimet 970 automatic image analyser so that the three-dimension structures regarding CD 34+ hematopoietic cells could be further made clear. By a series of measures including image scan-->modulus transform-->shadow correction-->image store-->statistical analysis, some morphometric parameters of CD 34+ hematopoietic cells were obtained as the followings: diametrs 3.490-6.741 microns, perimeters 11.776-26.240 microns, surface area 9.565-35.686 microns2, form factors 1.048-1.840, nucleus-plasma ratio 0.55-0.72, mean light density 0.17675-0.65100, integral light density 2717.217-46661.000. These morphometric data combined with our previous results from morphology, ultrastructure and functional subsets of CD 34+ hematopoietic cells strongly demonstrate that CD 34+ hematopoietic cells are really a heterogenous population. The possible reasons causing heterogeneous are close associated with either different functional subsets or differentiation lineages. To our knowledge, this is the first identification of sterological features of CD 34+ hematopoietic cells.

Antigens, CD34↗
PubMed1997

[Purification and properties of inulinase from Kluyveromyces sp. Y-85].

The crude endocellular inulinase from Kluyveromyces sp. Y-85 was purified to two components, designated as EI and EII, using PEG6000-phosphate buffer extraction, (NH4)2SO4 fractionation, DEAE chromatography and gel filtration (Protein-PAK); The crude exocellular inulinase from this strain was purified to Eexo by means of PEG6000-phosphate buffer extraction, double DEAE-Sephace chromatography, Sephadex G-150 gel filtration. EI, EII and Eexo were demonstrated to be homogeneous by Waters 650E protein purification system. Their molecular weights are 42 kD, 65 kD and 57 kD, respectively. All the inulinases were glycoproteins containing a saccharide (from 25% to 35%) and belonged to the endo-inulinase. In addition, EI, EII, Eexo were optimally reactive at pH4.6, 4.5, 4.6 and at 52 degrees C, 52 degrees C, 55 degrees C, respectively. Ag+, Hg2+ and PCMB inhibited these enzymes' activity strongly. The products of raw inulin extracted from Helianthus tuberosus hydrolyzed by these three enzymes were fructose (86.5%) and glycose (13.5%).

English Abstract↗
PubMed1997

[Morphological and cytochemitry features of CD34+ hematopoietic cells isolated from human bone marrow].

OBJECTIVE: To explore the cytomorphological and cytochemitry features of CD34+ hematopoietic cells. METHODS: Highly purified CD34+ hematopoietic cells isolated from human bone marrow by a two-step method of immunomagnetic beads-FACS sorting were comprehensively examined. RESULTS AND CONCLUSION: CD34+ hematopoietic cells could be sorted into three types in light of morphology and cytochemical staining. Type I was considered as candidates for stem cells,which were most blastlike in morphology and slightly larger than lymphocytes in size with negative reactions to all cytochemical stainings. Type II was considered as multipotent progenitor cells, with sizes similar to small lymphocytes and negative reactions to all cytochemical stainings. Type III was identified as committed progenitor cells whose sizes were heterogeneous and whose reactions to cytochemical stainings ranged from +/- to + +.

Antigens, CD34↗
PubMed1997

[Lecture of principles and applications of capillary electrophoresis (V) Applications of capillary electrophoresis in pharmaceutical analysis and clinical chemistry].

A review with 68 references is presented on the application and new developments of CE in pharmaceutical analysis, clinical chemistry and single cell analysis etc. The pharmaceutical analysis includes main component assay, determination of drug-related impurities, stoichiometric determination and quantitative determinations. The Chinese herb analysis includes determinations of main components and prescriptions of Chinese herb. The chiral separation includes separation mechanism and some new chiral selectors. The application of CE in clinical chemistry includes determinations of serum and protein, monitoring of drug metabolism, etc. Single cell analysis includes determinations of component in neurocells and human erythrocyte.

Animals↗
PubMed1997

[Study on separating characteristics in capillary reversed-phase electrochromatography].

Capillary Electrochromatography (CEC) driven by electroosmotic flow is a new technique using fused silica capillaries packed with HPLC-type stationary phase. The analytes are separated by normal chromatographic partition between a mobile phase and a stationary phase. By using electroosmotic flow driving mobile phase, CEC promises theoretical plate efficiencies for HPLC. In this paper, some separating characteristics in capillary electrochromatography were studied by carrying out the separation of some neutral compounds on capillary column with 75microm i.d. x 30cm/37cm packed with ODS particles (3microm). The mobile phase was acetonitrile and water, which contains certain concentration of electrolyte. Samples were injected electrokinetically into the separating column. On-line UV detector was used. The Joule heating effect in packed CEC was lower than that in CZE, and a good linear relationship between the elecrtoosmotic flow (EOF) velocity and applied voltage was obtained as shown in Fig. 1. The influence of electrolyte and acetonitrile concentrations on the electroosmotic flow was studied, as shown in Fig. 2 and 5. The EOF was monitored by using thiourea as a marker. The EOF will decrease when the electrolyte concentration increases. The higher the acetonitrile concentration was, the lower the EOF was. The effect of linear velocity on column efficiencies was also investigated. The column effeciencies less than 2. 0 reduced plate height were obtained. The highest efficiency obtained in this work was 236000 plate per meter for a retained solute, benzene. It was found that the concentrations of acetonitrile and electrolyte were important experimental variables in performance of capillary electrochromatography.

English Abstract↗
PubMed1997

[Evaluation of capillary chromatographic columns packed by electrokinetic packing method].

In this paper, a method for electrokinetic packing capillary columns is reported. A higher column effeciency was obtained by performing electrochromatography on electrokinetic packing columns. The highest column efficiency in number of theoretical plate per meter was more than 200000, corresponding to reduced plate height less than 2. The reproducibilities of the same column in different intervals and different columns prepared from the same or different batches were compared. The relative standard deviations of the number of theoretical plate and retention time were less than 10% and 8%, respectively. The results indicated that high column efficiency and good reproducibility can be obtained on these new capillary packed columns.

English Abstract↗