Biomedical subjects

Wei Hu

Publications and source records attributed to Wei Hu.

At least 109 records · Page 6Linked to original sources

PubMed2003

Raf-1 and Bcl-2 induce distinct and common pathways that contribute to breast cancer drug resistance.

Overexpression of Bcl-2 plays a role in the development of drug resistance in leukemia and other apoptosis-prone tumors. Raf isoforms areserine/threonine kinases that act as signal transducers in cascades initiated by many growth factors and mitogens. Raf isoform activation has been linked to drug resistance in leukemia. In this study we investigated effects of Bcl-2 and Raf-1 on doxorubicin-induced growth inhibition of MCF-7 breast cancer cells. In the absence of doxorubicin, overexpression of Bcl-2 or a constitutively active form of Raf-1 in MCF-7 cells did not affect proliferation rate. Overexpression of Bcl-2 increased resistance of MCF-7 cells to doxorubicin in 2-day, 5-day, and 8-week assays. Analysis of doxorubicin sensitivity of individual MCF/Bcl-2 clones showed that doxorubicin resistance was positively correlated with level of Bcl-2 overexpression. Overexpression of constitutively active Raf-1 also increased resistance to doxorubicin. Induction of Raf-1 activity in MCF-7 cells overexpressing Bcl-2 resulted in greater doxorubicin resistance than induction of Raf-1 activity in MCF-7 cells lacking Bcl-2 overexpression. Furthermore, levels of P-glycoprotein mRNA were increased in MCF-7 cells overexpressing a constitutively active Raf-1. MCF-7 cells overexpressing constitutively active Raf-1 were also more resistant to paclitaxel, which, like doxorubicin, is a substrate of P-glycoprotein. These observations suggest both independent and overlapping roles for Raf-1 and Bcl-2 oncogenes in the resistance to growth inhibition by doxorubicin.

ATP Binding Cassette Transporter, Subfamily B, Mem↗

PubMed2003

[Prevention of enamel demineralization adjacent to orthodontic brackets bonded with resin-modified glass ionomer: an in vitro pH cycling study].

OBJECTIVE: To investigate the resin-modified glass ionomer cement for inhibition of enamel demineralization adjacent to orthodontic brackets under a pH cycling experiment. METHODS: The study used 5 pairs of extracted human premolars. The experiment teeth were bonded with resin-modified glass ionomer, the control teeth were bonded with composite resin. All samples were under the pH cycling experiment each day for 60 days. Demineralization lesions of enamel adjacent to orthodontic brackets were evaluated with polarized light microscopy. The depth and area of the lesion, and the distance between the edge of the adhesive on the enamel surface and the border of the lesion were measured. RESULTS: The depth and area of lesions of control were greater than those of experiment group were. Paired t test showed significant differences (p < 0.001). There was always a distance between the lesions border and the glass ionomer cement. In control group, all lesions were developed under the edge of composite resin. CONCLUSION: It was suggested that resin-modified glass ionomer may become an orthodontic bonding agent to minimize enamel demineralization.

Glass Ionomer Cements↗

PubMed2003

[Prokaryotic expression of gene encoding Schistosoma japonicum SjE16 and its potential application in immunodiagnosis].

OBJECTIVE: To sub-clone and express the gene encoding Schistosoma japonicum calcium-binding protein (SjE16) and study its immunological response. METHODS: The specific primers were designed according to the expressed sequence tags (ESTs) sequence, which was used for amplification of the encoding sequence from the cDNA clone containing SjE16. The gene was subcloned into pGEX4T-1 plasmid and expressed. The rSjE16 was tested for its immunological response by ELISA. RESULTS: The gene encoding Schistosoma japonicum SjE16 was cloned and expressed successfully. The immunogenicity and diagnostic potential of rSjE16 were investigated. It was demonstrated by immunoassay in rabbits that the specificity and sensitivity of the test were 94.1% (16/17) and 88.2% (15/17), respectively, and the level of antibody titer of the untreated group reached a peak at 9-11 wk post infection and maintained high at least for 21 wk post infection, while the antibody level in the treated group rapidly decreased to pre-infection level in 11 wk after treatment. In human, the specificity of the test was 98.3% (57/58); the sensitivity of acute and chronic patient serum assay was 85.5% (53/62) and 70.2% (40/57), respectively. CONCLUSION: The recombinant protein of SjE16 (rSjE16) was acquired. It can be recognized by the sera from schistosomiasis patients, and the level of antibodies decreased quickly after treatment in experimental rabbits, which implicates the potential value for the evaluation of chemotherapy and detection of active infection.

Animals↗

PubMed2003

[The inhibitory effect of glass ionomer cement for orthodontic bonding on bacteria].

OBJECTIVE: To prove the inhibitory effect of glass ionomer cement for orthodontic bonding on bacteria. METHODS: Twenty-two persons were chosen randomly. In vivo, with the split-mouth technique, brackets were bonded with glass ionomer cement or composite resin respectively. Plaque samples were taken from the area of the adhesive one month after the placement of brackets and incubated for microbiologic analysis. RESULTS: There was no significant difference in the amount of total anaerobic bacteria with the two materials. There were also no obvious reduction of the numbers of S. mutans (the composite: 2.4 x 10(10) CFU/L, the glass ionomer cement: 2.8 x 10(10) CFU/L, P = 0.673) and its proportion (percentage of total CFU) with the use of glass ionomer cement compared with the composite. CONCLUSIONS: There was no long term inhibitory effect on bacteria adjacent to glass ionomer cement for orthodontic bonding.

Adolescent↗

PubMed2003

[Progress on mechanism of nuclear reprogramming after nuclear transfer].

Despite cloned animals becoming almost commonplace, there is no perfect cloning technique system yet and behind every success lies hundreds of failures. Moreover, cloned animals often age and die quickly. All of those problems hinder further research in nuclear transplantation. The key to make a break-through in the research of cloned animals relies on elucidating mechanism of nuclear reprogramming. Therefore, progress on nuclear reprogramming in nuclear transplantation has been reviewed in some aspects, for example remodeling of the nuclear structure, nucleocytoplasmic interactions and effects of the cell cycle, difference of gene expression and genomic imprinting between reconstructed embryos and fertilized embryos, etc. These results indicate that cytoplasmic environment is very important for the reprogramming of transplanted nuclei. When a donor nucleus in any stage of the cell cycle is transferred into the cytoplasm of an oocyte, there are the twin processes of structural remodeling and molecular reprogramming of the nucleus after transplantation. It is evident that the cell cycle coordination between donor cell and recipient cytoplast to avoid DNA damage and to maintain correct ploidy of the reconstructed embryo is of critical importance in determining the developmental capacity of reconstructed embryos. A dramatic reprogramming of gene expression occurs during zygotic gene activation. The time of zygotic gene activation may affect nuclear reprogramming and consequently the development of reconstructed embryo to off-spring. Imprinted genes are related to the reprogramming and aberrant development seen in manipulated embryos, and may be critical in the reprogramming of transplanted somatic cell.

Animals↗

PubMed2002

[Establishment of a new pig model for auxiliary partial orthotopic liver transplantation].

OBJECTIVE: To establish a new pig model for auxiliary partial orthotopic liver transplantation (APOLT). METHODS: The liver of the donor was removed from its body. The left lobe of the liver was resected in vitro, and the right lobe was used as a graft. After the left lateral lobe of the recipient was resected, end-to-side anastomoses were performed between the suprahepatic inferior venae cavae of the donor and between the portal veins of the donor liver and those of recipient liver respectively. End-to-end anastomosis was performed between the hepatic artery of graft and the splenic artery of host. Outside drainage was placed in the donor's common bile duct. RESULTS: Model of APOLT was established in 5 pigs with a success rate of 80%. The hemodynamics of the recipient was stable during and after operation. CONCLUSION: Significant decrease of congestion in portal vein and shortened blocking time were obtained because of the application of veno-venous bypass in vitro during complete vascular clamping. This new procedure, with such advantages as simple vessel processing, quality anastomosis, less postoperative hemorrhage and higher success rate, etc, effectively prevents ischemical reperfusion injury of the host liver and deserves to be spread.

Animals↗

PubMed2002

Spatial nonparaxial correction of the ultrashort pulsed beam propagation in free space.

In this paper, a family of integral solutions representing ultrashort pulsed beam propagation in free space is studied by using the comoving frame coordinates and the Fourier transformation for time variable in terms of well-known paraxial approximation. The pulsed Gaussian-like beam solution is obtained as a special case of the integral solution, where the pulsed Gaussian beam solution is included. Further, starting from the nonparaxial pulsed beam propagation equation in the temporal-frequency domain and making use of the spatial Fourier transform, the nonparaxial pulsed beam solution is derived based on the paraxial pulsed beam solution, where the nonparaxiality is evaluated by a series of expansions.

Journal Article↗

PubMed2002

[A study of the engraftment, expansion and differentiation of human hematopoietic stem cells in goats].

OBJECTIVE: To establish a human/goat hematopoietic stem cell (HSC) xenogeneic transplant model and to probe the engraftment, expansion and differentiation of human HSC in vivo. METHODS: Human HSCs were isolated from human umbilical cord blood and 1 x 10(5) human HSCs were in utero transplanted into 50 fetal goats at the 55 - 65 the gestation days. The engraftment, expansion and differentiation of human HSCs in goats were determined by FACS analysis, PCR and PCR-Southern blot hybridization at various intervals after birth. RESULTS: Hematopoietic chimerism occurred certainly in 35 of 39 live-born recipients. On average, The proportion of human hematopoietic cells in goat blood was 1% approximately 3% and remained phenotypically stable for at least 10 months. The human hematopoietic cells circulated in goat blood expressed CD34, CD14, CD20 and glycophorin A (GPA) but did not express CD3, CD4, CD7, CD8 and CD56 or expressed them at a very low level. CONCLUSION: The number of human HSC can be effectively expanded 1 000 - 10 000 fold. Human HSCs in goats undergo a limited differentiation. Our human/goat HSC xenogeneic model provides a useful way for the investigation of HSC transplantation, expansion and differentiation in vivo.

Animals↗

PubMed2002

A simple method to isolate salt-tolerant myxobacteria from marine samples.

This paper describes a simple method for the isolation of salt-tolerant myxobacteria from marine conditions. As the results show in this paper, salt-tolerant myxobacteria are found to be able to grow, but unable to form fruiting bodies at high salt concentrations. The fruiting body structures of the salt-tolerant strains were all formed in conditions with lower seawater content, i.e. lower than 60% seawater (about 2.0% salt content) or distilled water supplemented with MgCl(2). The method picked up the fruiting bodies for isolation.

Bacteriological Techniques↗

PubMed2002

Identification and validation of metastasis-associated proteins in head and neck cancer cell lines by two-dimensional electrophoresis and mass spectrometry.

Despite improvements in treatment of patients with head and neck squamous cell carcinoma (HNSCC) over the last two decades, the survival rate of these patients has not increased significantly. One of the major factors in the poor outcome of the disease is regional metastasis. To better understand the mechanisms of this process at the protein level, we performed two-dimensional electrophoresis (2-DE) and mass spectrometry using SELDI ProteinChip technology to identify proteins differentially expressed in two HNSCC cell lines, UMSCC10A and UMSCC10B, from the same patient. UMSCC10A was derived from the primary tumor and UMSCC10B from a metastatic lymph node. The differentially expressed proteins were excised from the gels. Following in-gel digestion by trypsin, mass profiles of the peptides were generated. Proteins were identified by submitting the peptide mass profiles to a public available NCBInr databases (www.proteometrics.com). Two membrane-associated proteins, annexin I and annexin II and glycolytic protein enolase-alpha were found to be upregulated, and calumenin precursor down-regulated, in metastatic cell line UMSCC10B. The identity of these proteins was confirmed by analyzing additional peptide mass fingerprints obtained by endoproteinase lysine-C digestion. The results were also validated by Western blotting analysis. Our results showed that enolase-alpha, annexin-I and annexin-II might be important molecules in head and neck cancer invasion and metastasis. The results also suggest an important complementary role for proteomics in identification of molecular abnormalities important in cancer development and progression.

Amino Acid Sequence↗

PubMed2002

The anti-apoptotic genes Bcl-X(L) and Bcl-2 are over-expressed and contribute to chemoresistance of non-proliferating leukaemic CD34+ cells.

In acute myeloid leukaemia (AML), cell kinetic quiescence has been postulated to contribute to drug resistance. As the anti-apoptotic genes Bcl-2 and Bcl-X(L) have been implicated in cell cycle regulation, we investigated the expression of these genes in non-proliferating (Q) and proliferating (P) AML and normal CD34+ progenitor cells. Using reverse transcription polymerase chain reaction, Bcl-X(L) and Bcl-2 were overexpressed in Q versus P AML cells, whereas no difference in Bcl-XS and Bax expression was found. Furthermore, the Bcl-X(L)/X(S) but not the Bcl-2/Bax ratio was higher in Q AML compared with normal CD34+ Q cells (P = 0.001). An inverse correlation between Bcl-2 expression of leukaemic Q cells and their ability to enter the cell cycle was found. Treatment with all-trans retinoic acid (ATRA) reduced Bcl-2 and Bcl-X(L) expression in the leukaemic Q cells, and enhanced their chemosensitivity to cytosine arabinoside (ara-C). These findings demonstrate overexpression of the anti-apoptotic proteins Bcl-X(L) and Bcl-2 in quiescent CD34+ AML cells and suggest their involvement in the chemoresistance. The observed inverse correlation between Bcl-2 and proliferation suggests a role for Bcl-2 in the cell cycle regulation of AML. These findings could be used in the development of therapies that selectively induce apoptosis in quiescent leukaemic progenitor cells.

Acute Disease↗

PubMed2002

Study on a novel strategy to treatment of phenylketonuria.

To replace the low phenylalanine (phe) diet treatment and to improve the quality of life of the phenylketonuria (PKU) patients, A phenylalanine ammonia-lyase (PAL) cDNA from petroselinum crispum was subcloned into expression vectors, pMG36e and pNZ8048, and transformed L. lactis by electroporation. The pMG36e PAL/L. lactis and pNZ8048 PAL/L.L. were screened and characterized by using PCR and HPLC, and prepared as a liquid type preparation that were given orally to treat hyperphenylalaninemia-rats. The phe levels of the rat plasma sample were determined by HPLC. The data showed that the plasma phe levels in hyperphenylalanemia (HPA) rats receiving preparations made from the engineered L. lactis were significantly reduced compared with non-treated HPA rats. The effect of the pNZ8048PAL/L.L. showed a higher expression of PAL and better cure results than pMG36ePAL/L.L. These results point a potential way for PKU treatment.

Administration, Oral↗

PubMed2002

Children's respiratory morbidity prevalence in relation to air pollution in four Chinese cities.

We examined respiratory health effects of long-term exposure to ambient air pollution in 7,621 schoolchildren residing in eight districts of four Chinese cities. The four cities exhibited wide between-city and within-city gradients in ambient levels of four size fractions of particulate matter [less than or equal to 2.5 micro m in aerodynamic diameter (PM(2.5)), between 2.5 and 10 micro m (PM(10-2.5)), less than or equal to 10 micro m (PM(10)), and total suspended particulates (TSP)] and two gaseous pollutants (SO(2) and NO(x)). Informed consent and written responses to questionnaires about children's personal, residential, and family information, as well as their health histories and status, were obtained with the help of the parents and the school personnel. We used a two-stage regression approach in data analyses. In the first-stage logistic regressions, we obtained logits of district-specific prevalence of wheeze, asthma, bronchitis, hospitalization for respiratory diseases, persistent cough, and persistent phlegm, adjusted for covariates representing personal, household, and family parameters. Some of these covariates were found to be risk factors of children's respiratory health, including being younger in the study group, being male, having been breast-fed, sharing bedrooms, sharing beds, room being smoky during cooking, eye irritation during cooking, parental smoking, and a history of parental asthma. In several of the second-stage variance-weighted linear regressions, we examined associations between district-specific adjusted prevalence rates and district-specific ambient levels of each pollutant. We found positive associations between morbidity prevalence and outdoor levels of PM of all size fractions, but the association appeared to be stronger for coarse particles (PM(10-2.5)). The results also present some evidence that ambient levels of NO(x) and SO(2) were positively associated with children's respiratory symptoms, but the evidence for these two gaseous pollutants appeared to be weaker than that for the PM.

Adolescent↗

PubMed2002

Ultrashort pulsed bessel beams and spatially induced group-velocity dispersion.

We find a new family of solutions of the nonparaxial wave equation that represents ultrashort pulsed light beam propagation in free space. The spatial and temporal parts of these pulsed beams are separable; the spatial transverse part is described by a Bessel function and remains unchanged during propagation, but the temporal profile can be arbitrary. Therefore the pulsed beam exhibits diffraction-free behavior with no transverse spreading, but the temporal part changes as if in a dispensive medium; the change is dominated by what we call spatially induced group-velocity dispersion. The analytical and numerical investigations show that the even- and odd-order spatially induced dispersions partially compensate for each other so as to give rise to pulse spreading, weakening, asymmetry, and center shift.

Journal Article↗

PubMed2002

[Effects of sulphur dioxide on the relationship between symbionts in lichen].

Xanthoparmellia mexicana was successfully isolating and culturing from its two symbionts and, preliminarily re-symbiosising its thalli in vitro performed from pure cultured photobiont and mycobiont. The solution exposure method was applied, confirming the toxic effect of sulfite solution with pH 4.0. The biochemical responses of lichen thalli and cultured symbionts to the short time stress of SO2 were studied. The chlorophyll PQa value of photobiont was correlated with its absorption of SO2. Chlorophyll a was more sensitive than chlorophyll b; chlorophyll was damaged most severely by the exposure of 0.5 mg.L-1 of SO2 fumigation, but was aggravated with the increase in the concentration of SO2 by way of solution exposure. The activity of acid phosphatase in lichen was mainly dependent on the photobiont. Reduced glutathione(GSH) was activated by oxidative stress of SO2. GSH was confirmed to be highly correlated with SO2 stress, and was proposed to be a significant and prospective biomarker of the status of lichen antioxidant system and the oxidative damage in lichen. The mycobiont was proposed to mainly resist the oxidative stress by SO2, while the photobiont was damaged more easily with energy depletion.

Ascomycota↗

PubMed2002

[Diversity of 16s rDNA ribotypes of the Salmonella typhi strains isolated in Guizhou province].

OBJECTIVE: To analyses the genetic diversity and relationship of Salmonella typhi strains isolated from different years and districts in Guizhou province. METHODS: Ribotyping with 16s rDNA probe was used to describe the diversity of the 209 strains which were isolated in 26 counties of Guizhou province, from 1959 to 1999. The antibiotics resistance was also studied. RESULTS: Twenty-six ribotypes were found in all 209 strains, with two dominant types. The strains isolated from local typhoid epidemics belonged to the unique Ribotypes. The major ribotypes of the resistant strains were RT7 and RT1. CONCLUSION: The Salmonella typhi isolates from Guizhou diverged obviously. The abundant clones and multi-resistance of the strains might serve the major reasons of the high morbidity of typhoid in Guizhou.

Blotting, Southern↗

PubMed2002

[Studies of F1 of transgenic allotetraploid hybrids of Carassius auratus red var. (Female) x Cyprinus carpio (Male)].

The tetraploid fish has been developed by assortative breeding the hybrids of Carassius auratus red var. (Female) x cyprinus carpio (Male), which has the stable genetic characters and can reproduce themselves. An "all-fish" recombinant DNA construct (pCAgcGHc) containing common carp beta-actin gene promoter and cDNA for grass carp (Ctenopharyngodon idella) growth hormone gene was introduced into fertilized eggs of the allotetroploid fish through microinjection as soon as artificial insemination was done. Artificial insemination was carried out between the female and the male transgenic allotetraploid fish which contain the "all-fish" recombinant DNA construct (pCAgcGHc) and are the biggest in the size. Fifty F1 samples of transgenic allotetraploid fish of 150 days and 50 allotetraploid fish (regarded as the control) were chosen, and the weight and the body length of each were measured, the results showed that F1 of transgenic allotetraploid fish of 150 days had obvious growth dominance compared with the control. Genomic DNA of tail fin was extracted from 20 F1 of transgenic allotetraploid fish of 150 days and the control. Proper primers were introduced to check whether the sample had the transgene. Pa, the upstream primer, is located in beta-actin promoter, and Pg, the downstream primer, is located in growth hormone cDNA for grass carp (gcGHc). The transgene was detected in 90% F1 of transgenic allotetraploid fish in tail fin DNA by polymerase chain reaction (PCR) amplification. Sperm could be squeezed out from a few F1 of transgenic allotetraploid fish of 150 days, however, this phenomenon did not exist in the controls. The importance of forming the pure line of transgenic allotetraploid was elucidate in the paper.

Animals↗

PubMed2002

The compensation of dental arch and teeth in patients with skeletal protrusion and deviation of mandible.

OBJECTIVE: To investigate the compensation of dental arch and teeth in patients with skeletal protrusion and deviation of mandible. METHODS: Measurement of 11 dental models was performed, midline of palate was defined as central line, the distance of every contact point to the midline was measured in each side. The dental arch symmetry was observed. Occlusion plane was defined as conference plane, the buccal or lingual inclination of posterior teeth in upper and lower arch was measured. RESULTS: Upper arch was asymmetry in these patients, the arch width of deviated side (the side that the chin was deviated to) was broader than the other side. The posterior teeth of upper and lower arch were more buccally and lingually inclined respectively. CONCLUSIONS: Skeletal protrusion and deviation of mandible may result in compensation of dental arch and teeth, the de-compensation is important in pre-operative orthodontic treatment.

Dental Arch↗