Biomedical subjects
Publications and source records attributed to Chen Xu.
The B(6) vitamers have been shown to display beneficial therapeutic effects in cardiovascular related disorders. The design of novel antiplatelet agents using pyridoxine as a template has led to the discovery of a class of novel cardio- and cerebro-protective agents. The present study describes the synthesis of several of these derivatives along with the antiplatelet and antiischemic activity of derivative 16.
Plantago asiatica, Scrophularia ningpoensis and Ilex pubescens are among the traditional Chinese medicines which are more frequently prescribed for treating depression-like ailments in the past and present traditional Chinese medical practice. The present work was therefore conducted to evaluate the presumable antidepressant effects of the extracts derived from the three remedies in mice using the learned helplessness model being used for screening for antidepressant compounds in modern medicinal researches. As a result, the petroleum extracts of Plantago asiatica and Ilex pubescens as well as the EtOAc extract of Scrophularia ningpoensis and the petroleum-soluble fraction of the acidic hydrolysate of the water extract of Ilex pubescens (after petroleum extraction) decreased significantly the number of escape failures relative to the control. The finding rationalized the clinical prescription of the herbs for the treatment of depression, and shined a clue for the characterization of the antidepressant phytochemical(s).
AIM: To investigate the spatial and temporal expression of germ cell nuclear factor (GCNF) in mouse and rat epididymis during postnatal period. METHODS: The epididymal sections from different postnatal days were stained for GCNF by the indirect immunofluorescence technique and digital photographs were taken by a Carl Zeiss confocal microscope. RESULTS: GCNF was first detected on day 12 in mouse epididymis and day 14 in rat epididymis. The highest expression of GCNF was observed on day 35 in both mouse and rat epididymis. In adults, GCNF exhibited a region-specific expression pattern, i.e., it was expressed predominantly in the initial segment, caput and proximal corpus of rat epididymis and was abundant in the proximal corpus of mouse epididymis. GCNF could be found in the nuclei of the principal, apical, narrow, clear and halo cells. CONCLUSION: GCNF may play an important role in epididymal differentiation and development and in sperm maturation.
OBJECTIVE: To investigate the expression pattern of the cystatin-related epididymal spermatogenic (Cres) gene in mouse testes and epididymis during postnatal development. METHODS: Semi-quantitative RT-PCR was used to detect the Cres mRNA level in postnatal mouse testes and epididymis on day 14, 20, 22, 28, 35, 49, 70 and 400. RESULTS: Low-level Cres mRNA was detected on day 14 in both the testes and the epididymis. The expression of the Cres gene increased gradually with the development of the mouse, and it reached the peak on day 70 in the testes and on day 400 in the epididymis. CONCLUSION: The time-dependent expression pattern of the Cres gene in postnatal mouse testes and epididymis suggested that the Cres gene might be involved in the regulation of spermatogenesis and sperm maturation.
It is well known that mycoplasma can cause infection in the male reproductive tract. Some studies indicate that Ureaplasma urealyticum (Uu), a species of mycoplasma, is associated with male infertility. Sulfogalactosylglycerolipid(SGG) is the major mammalian male germ cell glycolipid, synthesized via sulfation of galactosylglycerolipid in early primary spermatocytes. Some experiments have proved that SGG is implicated in sperm-egg binding by linking arylsulfatase A (AS-A), SGG's ligand on the egg. SGG can be desulfated by binding mycoplasmas and transformed galactosylglycerolipid, which doesn't bind AS-A. So the binding and degradation of the sperm SGG by mycoplasmas may play a role in the induction of male infertility. As a kind of mycoplasma, Uu can also bind SGG, which offers another explantion for the association of Uu infection with male infertility caused by Uu infection.
AIM: To assess the spatial and temporal expression of germ cell nuclear factor (GCNF) in male mouse germ cells during postnatal development and in sperm before and after capacitation. METHODS: The indirect immunofluorescence method with anti-GCNF antiserum was used to investigate the GCNF expression in mice at day 8, 10, 14, 17, 20, 28, 35, 70, and 420 after birth and in sperm before and after capacitation. RESULTS: With the proceeding of spermatogenesis, GCNF was first detected in the nuclei of spermatogonia and a few early stage primary spermatocytes at day 8, which was increased gradually at day 10 to 14 inclusive. From day 17 to day 20, the GCNF was concentrated in round spermatids, while both spermatogonia and early stage primary spermatocytes became GCNF negative. From day 28 until day 420, strong GCNF expression was shown in round spermatids and pachytene spermatocytes, while spermatogonia, early primary spermatocytes and elongating spermatids were all GCNF negative. In addition, it was also found that GCNF was localized on the acrosomal cap region of spermatozoa and there was a big change in GCNF expression during capacitation, from 98 % GCNF positive before capacitation to about 20 % positive following capacitation. The localization of GCNF in caput and cauda spermatozoa was similar. CONCLUSION: GCNF may play important roles in spermatogenesis, capacitation and fertilization.
The sequences of nrDNA regions of 17 species and Phyllostachys edulis (outgroup) sampled, which are of represent and type species for different taxa in the genus Arundinaria,were analyzed by PCR amplification and direct DNA sequencing. The phylogenetic trees generated from maximum parsimony analysis showed that the sampled bamboos were naturally monophletic, appearing that these species of the bamboos belong to the genus Arundinaria. The internal transcribed spacers (ITS) data indicated that the species were divided into two branches, one including A. oleosa, A. hsienchuensis, A. chino, A. amara, A. yixingensis, A. amabilis, A. fortunei, and A. pygmaea, the other including A. graminea, A. fargesii, A. faberi, A. hupehensis, Pseudosasa japonica cv. Tsutsumiana, P. japonica, Brachystachyum densiflorum, A. oedogonata, and A. sulcata. The result also showed that there was close relationship between A. graminea and A. fargesii, Pseudosasa japonica cv. Tsutsumiana and P. japonica, A. sulcata, Brachystachyum densiflorum and A. oedogonata, (99%, 100% and 82% boot-strap support respectively). Moreover, there was very close relationship between A. amabilis and A. hsienchuensis, indicating that A. amabilis belongs to the genus Arundinaria. It was shown in the phylogenetic tree that A. pygmaea and A. fortunei had close relationship, and were a sister branch to the bamboos of Pleioblastus.
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OBJECTIVE: To study the influence of Ureaplasma urealyticum (Uu) infection on the sperm-egg binding associated molecule, sulfogalactosylglycerolipid (SGG). METHODS: Epididymal sperm was collected from adult mice. The sperm suspension was randomly divided into 4 groups: Uu group (coincubated with Uu suspension), medium group (coincubated with Uu medium), normal group and PRS group. The indirect immunofluorescence technique was used to localize SGG on the sperm membrane and to observe the influence of Uu on SGG. RESULTS: In the epididymal sperm, SGG was localized to the head plasma membrane overlaying the acrosomal region. The SGG-positive rate of the sperm coincubated with Uu medium was 82.0%, while that of the sperm coincubated with Uu suspension was reduced to 39.0% (P = 0.001). CONCLUSION: Uu can adhere to the sperm surface. SGG might be a membrane receptor on the sperm surface for Uu infection of the mammalian male genital tract. The blockage of SGG by Uu might be one of the molecular mechanisms correlative to male infertility induced by Uu infection.
Intrauterine infection is an important cause of some birth defects worldwide. The most common pathogens include rubella virus, cytomegaloviurs, ureaplasma urealyticum, toxoplasma, etc. General information about these pathogens in epidemiology, consequence of birth defects, and the possible mechanisms in the progress of birth defects, and the interventions to prevent or treat these pathogens' infections are described. The infections caused by rubella virus, cytomegaloviurs, ureaplasma urealyticum, toxoplasma, etc. are common, yet they are proved to be fatal during the pregnant period, especially during the first trimester. These infections may cause sterility, abortion, stillbirth, low birth weight, and affect multiple organs that may induce loss of hearing and vision, even fetal deformity and the long-term effects. These pathogens' infections may influence the microenvironment of placenta, including levels of enzymes and cytokines, and affect chondriosome that may induce the progress of birth defect. Early diagnosis of infections during pregnancy should be strengthened. There are still many things to be settled, such as the molecular mechanisms of birth defects, the effective vaccines to certain pathogens. Birth defect researches in terms of etiology and the development of applicable and sensitive pathogen detection technology and methods are imperative.
Inhibition of BCR-ABL tyrosine kinase activity has shown to be essential for the treatment of chronic myelogenous leukemia (CML). However, drug resistance has quickly arisen in recent clinical trials for STI571 (Gleevec), which is the first approved drug of CML by inhibiting ABL tyrosine kinase. It is desirable to develop new types of ABL tyrosine kinase inhibitors that may overcome this drug resistance problem. Here we present the discovery of novel inhibitors targeted at the catalytic domain of ABL tyrosine kinase by using three-dimensional database searching techniques. From a database containing 200,000 commercially available compounds, the top 1000 compounds with the best DOCK energy score were selected and subjected to structural diversity and drug likeness analysis, 15 compounds were submitted for biological assay. Eight out of the 15 showed inhibitory activity against K562 cells with IC(50) value ranging from 10 to 200 microM. Two promising compounds showed inhibition in further ABL tyrosine phosphorylation assay. It is anticipated that those two compounds can serve as lead compounds for further drug design and optimization.
To generate human antibodies against CXCR4, a seven-transmembrane chemokine receptor and a principal coreceptor for HIV-1, several rounds of Pathfinder and Step-back selection from a large phage display antibody library were performed on Jurkat cells. A mAb against CXCR4 or biotinyated phage antibodies were used as guide molecules. Over 100 pan-Jurkat-cell-positive antibodies were characterized, but none were CXCR4 specific. However, several antibodies against CD4 and the transferrin receptor were identified. Our results indicate that, although Pathfinder and Step-back selection can be used to select phage antibodies on whole cells, the successful selection of certain targets is still complex and limited. The reason is probably, in part, due to the inaccessibility of the targeted extracellular structures and the range of the horseradish peroxidase-labeled guide molecule. Refinements of these techniques are required to improve target specificity and selectivity.
Germ cell nuclear factor (GCNF), a nuclear orphan receptor, involved in spermatogenesis, neurogenesis, differentiation, and embryo development, was highly expressed with two transcripts (7.4 and 2.3 kb) in mouse testis and with only one transcript (7.4 kb) slightly expressed in brain, liver, and kidney. The 2.3-kb transcript was restricted to round spermatids at stages VII and VIII of the spermatogenic cycle. The present report demonstrated its expression in epididymis as well, but at a very low level. Northern blot analysis showed two transcripts: a common 7.4-kb transcript and a unique 3.1-kb transcript. The expression levels of both GCNF transcripts in epididymis were down-regulated by androgen, as observed in castrated animals and aged mice. Polyclonal antisera against GCNF protein were raised. Western blot analysis showed the presence of only one band in total protein extracts from either mouse testis or epididymis. It indicated that the two mRNAs (7.4 and 3.1 kb) encode for the same protein as in testis. Fluorescent immunohistochemical staining and in situ hybridization showed that its expression was in the principal cell abundant in the corpus region. It implies that some androgen-regulated gene expressions located at the corpus principal cells might be controlled by GCNF.
AIM: To design and evaluate the small peptide mimetic of anti-P-glycoprotein (P-gp) antibody (PHMA02). METHODS: From the three dementional structure analysis of computer modeling of PHMA02 CDR loops, a small peptide mimetic was designed and determined by flow cytometry. RESULTS: Anti-P-gp peptide mimetic functionally similar to PHMA02 was developed. The peptide mimetic competitively inhibits PHMA02 binding to P-gp and partially block the P-gp function as a drug efflux pump in K562/A02 cells. CONCLUSION: Some special conformational properties of CDR loops of antibody might serve as lead structures for develop new biological peptide mimetics. Antibody-structure-based design would develop new drug in the future.
The anti-CD3 antibody can improve success rate of organs transplant. HIT3a, a mouse anti-CD3 antibody, was chimerized by using gene engineering methods to decrease its immunogenity. The anti-CD3 genes, heavy chain and light chain, were cloned using PCR from the vector pCANTAB 5E containing anti-CD3 scFv gene fragment, and two PCR fragments were recombined into the expression vector pKN100 with human antibody light constant domain and pG1D105 with human antibody heavy constant domain, respectively. The two vectors were co-transfected into CHO cells using liposome. The anti-CD3 antibody was detected by ELISA and Western blot assay in supernatant of transfected CHO cells culture. The primary results of competitive assays by FACS showed that anti-CD3 antibody could partially block the sites through which parent antibody (HIT3a) bind to CD3+ Jurkat cells. The result of 3H-TdR incorporation showed that the chimeric anti-CD3 antibody could stimulated proliferation of peripheral blood mononuclear cells (PBMC) as the parent antibody. In this thesis, the results of some experiments indicated that the chimeric anti-CD3 antibody expressed in CHO cells was an antibody with native biological activity, and it is possible to apply to in clinic in the future.
Ca(2+)-ATPase is responsible for active transport of calcium ions across the sarcoplasmic reticulum membrane. This coupling involves an ordered sequence of reversible reactions occurring alternately at the ATP site within the cytoplasmic domains, or at the calcium transport sites within the transmembrane domain. These two sites are separated by a large distance and conformational changes have long been postulated to play an important role in their coordination. To characterize the nature of these conformational changes, we have built atomic models for two reaction intermediates and postulated the mechanisms governing the large structural changes. One model is based on fitting the X-ray crystallographic structure of Ca(2+)-ATPase in the E1 state to a new 6 A structure by cryoelectron microscopy in the E2 state. This fit indicates that calcium binding induces enormous movements of all three cytoplasmic domains as well as significant changes in several transmembrane helices. We found that fluorescein isothiocyanate displaced a decavanadate molecule normally located at the intersection of the three cytoplasmic domains, but did not affect their juxtaposition; this result indicates that our model likely reflects a native E2 conformation and not an artifact of decavanadate binding. To explain the dramatic structural effect of calcium binding, we propose that M4 and M5 transmembrane helices are responsive to calcium binding and directly induce rotation of the phosphorylation domain. Furthermore, we hypothesize that both the nucleotide-binding and beta-sheet domains are highly mobile and driven by Brownian motion to elicit phosphoenzyme formation and calcium transport, respectively. If so, the reaction cycle of Ca(2+)-ATPase would have elements of a Brownian ratchet, where the chemical reactions of ATP hydrolysis are used to direct the random thermal oscillations of an innately flexible molecule.
A study evaluated a training-of-trainers strategy to update HIV/AIDS knowledge and improve attitudes and behavior among health professionals and the public. A survey was carried out among health workers and villagers. An initial workshop was given to 55 staff from several health institutions. Trainees were provided limited funds to conduct secondary workshops at local levels. They were requested to diffuse knowledge to patients during routine health visits. A follow-up survey was conducted 18 months later in counties in which workshops were not held. Knowledge, attitudes, and behavior were compared both at the baseline and follow-up surveys, and before and after the intervention. Nearly 95% (94.8%, or 13,782) of health workers in Fuyang Prefecture were trained secondarily at local levels. Knowledge was significantly higher in intervention (88.5-99.8%) compared with nonintervention (37.4-53.7%) counties, and after intervention (22.2-66.6%), respectively (p < .01). Attitudes toward people with HIV/AIDS improved significantly in intervention counties. Condom use during last sexual intercourse increased from 11.0% to 33.5% in health workers (p < .01) and from 8.7% to 18.5% among villagers (p <.01). The strategy wascost effective for improving knowledge and attitudes and promoting condom use.
OBJECTIVE: To study the protective effects of Tripterine on experimental lupus nephritis glomerulosclerosis. METHODS: Different doses of Tripterine were injected peritoneally to BW F1 mice at different stages. 24-hour urine protein excretion, serum anti-dsDNA antibodies, renal pathology and RT-nested PCR were analyzed to study the preventive effects of Tripterine on LN glomerulosclerosis and its mechanisms. RESULTS: (1) Tripterine suppressed the development of proteinuria, decreased the level of serum anti-dsDNA antibodies, reduced the expressions of collagen type IV, fibronectin, TIMP-1, TIMP-2, TGF-beta(1) and improved the expressions of MMP-1, -2 in the murine kidney. (2) The use of Tripterine before occurrence of proteinuria had more obvious protective effects than its use after the occurrence of proteinuria. (3) No significant difference was found between the 3 mg/kg/week Tripterine-treated-group and the 6 mg/kg/week Tripterine-treated-group. (4) No obvious change was observed in the expression of MMP-3. CONCLUSIONS: Tripterine has a definite protective effect on glomerulosclerosis of the lupus murine model. The decrease of renal collagen type IV and fibronectin is probably due to its suppressive effect on the expressions of local TGF-beta(1) and TIMP-1, -2, and its improvement effect on the local expressions of MMP-1, -2. Tripterine may have no obvious influence on MMP-3 in this model.