Biomedical subjects

Y Fan

Publications and source records attributed to Y Fan.

At least 91 records · Page 5Linked to original sources

PubMed2000

[Influence of the administrators of family planning on the spread of norplant in countryside of Sichuan].

The purpose of the study was to understand the family planning administrators' knowledge of Norplant and their fluence on the spread of Norplant in countryside of Sichuan. 156 administratoras were surveyed. It was found that most of the administrators worked hard on education, propagation, organization and management of using Norplant, and they recognized the contraceptive efficacy of Norplant. However, the educational level of the administrators was generally low. They were short of the training on Norplant related knowledge(training rate was only 36.5%). The degree of the users' satisfaction and the administrators' knowledge on Norplant varied between areas. The result indicated that the basic quality of the administrators and their knowledge of Norplant were influences on the spread of Norplant in the countryside of Sichuan. Soit is very important to improve the basic quality and knowledge of the administrators of family planning.

Adolescent↗

PubMed2000

[Effects of components isolated from Astragalus membranaceus Bunge on cardiac function injured by myocardial ischemia reperfusion in rats].

OBJECTIVE: To investigate the effects of components isolated from Astragalus membranaceus on myocardial ischemia reperfusion injury. METHODS: The myocardial ischemia reperfusion injury model was created by the left anterior descending coronary artery occlusion from the oracotouated rats, and the total saponins, total flavonids and astragaloside i.v. isolated from A. membranaceus on hemodynamics during acute myocardial ischemia, Na(+)-K(+)-ATPase activity, cAMP and malondialdehyede (MDA) contents in the ischemic myocardium were observed. RESULTS: The total saponins, total flavonids and astragaloside i.v. attenuated the declines of the amplitudes of LVSP and +/- LVdp/dtmax in rat heart injured by ischemia reperfusion in vivo, and decreased Na(+)-K(+)-ATPase activity in the ischemic myocardium. Otherwise, the total saponins increased the cAMP content and the total flavonids decreased the level of MDA production in the ischemic myocardium. CONCLUSION: The effects of different components isolated from A. membranaceus on protecting the cardiac function in the process of ischemia reperfusion may be related to the mechanism of improving energy metabolism, scavenging the oxygen free radicals and inhibiting the production of free radicals in the ischemic myocardium.

Animals↗

PubMed2000

[Alternative splicing of de novo methyltransferase gene 3b in adult and newborn mice].

OBJECTIVE: To unravel the biological significance of the alternative splicing of de novo methyltransferase 3b, expression of the Dnmt3b gene in various tissues and developmental stages was investigated in postnatal mice. METHODS: RT-PCR and capillary electrophoresis were employed to analyze the alternative splicing pattern of Dnmt3b in tissues of newborn and adult mice. The results had been further reaffirmed by repeating and statistics analysis. Bioinformatics tools were used to predict the structure and hydrophobicity of the Dnmt3b exon10 coding sequence. RESULTS: Isoform with Dnmt3b exon10 was the abundant form in lung of newborn mice and in liver of both newborn and adult mice, while in other tissues of newborn and adult mice, the spliced isoform was presented as the predominant one. Peptide encoded by Dnmt3b exon10 was mainly random coil on the surface of Dnmt3b protein. CONCLUSIONS: The data demonstrate that the specific expression of Dnmt3b exists in tissues and developmental stages of postnatal mice. The alternative splicing of the exon 10 of Dnmt3b is possibly involved in the regulation of Dnmt3b's catalytic function. These results provide an insight into the developmental regulation and physiological function of the alternative splicing of the Dnmt3b gene.

Alternative Splicing↗

PubMed2000

[Infrared study on molecular structure and orientation in Langmuir-Blodgett films of chiral LCs M1].

The LB films of chiral LCs M1 were investigated by FTIR transmission and reflection absorption spectra. CaF2 and vacuum deposition gold plate were used as solid substrate. The LB films can be transferred onto the solid substrate successfully. The orientation of LB films was analysis by comparing the FTIR transmission and reflection absorbance spectroscopy. The aromatic cores part which including the C-O bond was almost perpendicular the substrate surface, the alkyl chain and C=O part has a certain angle titled onto the substrate.

English Abstract↗

PubMed1999

Migration behavior and separation of active components in Glycyrrhiza uralensis Fisch and its commercial extract by micellar electrokinetic capillary chromatography.

A micellar electrokinetic capillary chromatography (MECC) method for the separation and determination of five components, glycyrrhizic acid (GA), glycyrrhetinic acid (GTA) and 3,4'-dimethoxy-5-hydroxychalone, fermononetin and isoliquiritigenin, in extracts of Glycyrrhiza uralensis Fisch root was developed. Migration behavior of these analytes was studied by the systematic examination of the borate and sodium dodecyl sulfate (SDS) concentrations in the run buffer. The optimum separation for these analytes was achieved using 10 mmol l(-1) of tetraborate and 25 mmol l(-1) of SDS as the running buffer, with 17 kV of applied voltage. All experiments were performed using a 50.0 cm (42.4 cm effective length)x75 microm I.D. of fused-silica capillary. The apparent pKa values of GA and GTA and the binding constants for the association between the above five analytes and SDS were calculated in this study. A comparison of the extraction efficiency for GA and GTA from Glycyrrhiza uralensis Fisch root was made using ethanol, distilled water and chloroform as extraction reagents, respectively. These results provided very useful information to select the proper solvent to extract the desired components in Glycyrrhiza uralensis Fisch. The MECC method established in this paper was employed to analysis the above five active components.

Acids↗

PubMed1999

Preparation, Characterization, and Catalytic Properties of Ultrafine Mixed Fe-Mo Oxide Particles.

Ultrafine mixed Fe-Mo oxide particles are prepared by the sol-gel technique using citric acid as a complex agent. The formation process of the ultrafine oxides is studied by using XRD, DTA-TG, FT-IR, TEM, and BET surface area measurement. It is found that the morphology and structure of the oxide particles are significantly dependent on the process parameters such as thermal treatment temperature (T), pH of the starting solution, and the molar ratio of citric acid to metallic ions (L/M). The formation temperature of crystalline Fe(2)(MoO(4))(3) by the sol-gel process is much lower than that by the coprecipitation method. The catalytic properties of ultrafine Fe-Mo oxide particles are tested and compared with those of large oxide particles having the same composition. It is shown that for selective oxidation of toluene to benzaldehyde the ultrafine Fe-Mo oxide particles exhibit higher benzaldehyde selectivity and toluene conversion than the large oxide particles. The unique catalytic properties of ultrafine Fe-Mo oxide particles may be correlated to the higher mobility of lattice oxygen species in the ultrafine oxide particles and their higher BET surface area. Copyright 1999 Academic Press.

Journal Article↗

PubMed1999

Chemotaxis of rat mast cells toward adenine nucleotides.

Rat mucosal mast cells express P2 purinoceptors, occupation of which mobilizes cytosolic Ca2+ and activates a potassium conductance. The primary function of this P2 system in mast cell biology remains unknown. Here, we show that extracellular ADP causes morphological changes in rat bone marrow-cultured mast cells (BMMC) typical of those occurring in cells stimulated by chemotaxins, and that the nucleotides ADP, ATP, and UTP are effective chemoattractants for rat BMMC. ADP was also a chemotaxin for murine J774 monocytes. The nucleotide selectivity and pertussis toxin sensitivity of the rat BMMC migratory response suggest the involvement of P2U receptors. Poorly hydrolyzable derivatives of ADP and ATP were effective chemotaxins, obviating a role for adenosine receptors. Buffering of external Ca2+ at 100 nM or reduction of the electrical gradient driving Ca2+ entry (by elevating external K+) blocked ADP-driven chemotaxis, suggesting a role for Ca2+ influx in this process. Anaphylatoxin C5a was a potent chemotaxin (EC50 approximately 0.5 nM) for J774 monocytes, but it was inactive on rat BMMC in the presence or absence of laminin. Ca2+ removal or elevated [K+] had modest effects on C5a-driven chemotaxis of J774 cells, implicating markedly different requirements for Ca2+ signaling in C5a- vs ADP-mediated chemotaxis. This is supported by the observation that depletion of Ca2+ stores with thapsigargin completely blocked migration induced by ADP but not C5a. These findings suggest that adenine nucleotides liberated from parasite-infested tissue could participate in the recruitment of mast cells by intestinal mucosa.

Adenine Nucleotides↗

PubMed1999

p53 and Egr-1 additively suppress transformed growth in HT1080 cells but Egr-1 counteracts p53-dependent apoptosis.

The human fibrosarcoma cell line, HT1080, clone H4, was used to determine if the transformation suppressive functions of p53 and Egr-1 have the same underlying mechanism. This cell line expresses only mutant p53 and no detectable Egr-1. H4 clones stably expressing Egr-1 are less transformed in proportion to the level of Egr-1 expressed, acting through the induction of the TGFbeta1 gene. Here, H4 cells and the highest Egr-1 expressing clone were transfected with a vector expressing normal human p53 to derive stable clones expressing p53. The expression of p53 in H4 cells inhibited transformed growth and reduced tumorigenicity. The effect of coexpression of both p53 and Egr-1 was additive, producing cell lines with 30% of normal growth rate and sevenfold reduced tumorigenicity compared with control lines. These results indicated that each factor may act independently by different pathways, although each additively increased the level of p21WAF1 cell cycle inhibitor. However, exposure of the H4-derived cells to UV-C irradiation produced contrasting effects. Cell cycle analyses showed that the presence of p53 was associated with loss of the G1 and S cells to apoptosis after irradiation. In contrast, the expression of Egr-1 increased entry into S/G2 phase of the cell cycle with little apoptosis via a mechanism involving elevated FAK and low caspase activities. Apoptosis was observed only in the cell lines that expressed no Egr-1, especially those expressing wt-p53, and was preceded by high caspase activity. In summary, Egr-1 suppressed transformation and counteracted apoptosis by the coordinated activation of TGFbeta1, FN, p21 and FAK, leading to enhanced cell attachment and reduced caspase activity. In the doubly expressing cell line, the survival effect of Egr-1 was dominant over the apoptotic effect of p53.

Apoptosis↗

PubMed1999

Forced expression of the homeobox-containing gene Pem blocks differentiation of embryonic stem cells.

Similarities in the differentiation of mouse embryos and ES cell embryoid bodies suggest that aspects of early mammalian embryogenesis can be studied in ES cell embryoid bodies. In an effort to understand the regulation of cellular differentiation during early mouse embryogenesis, we altered the expression of the Pem homeobox-containing gene in ES cells. Pem is normally expressed in the preimplantation embryo and expressed in a lineage-restricted fashion following implantation, suggesting a role for Pem in regulating cellular differentiation in the early embryo. Here, we show that the forced expression of Pem from the mouse Pgk-1 promoter in ES cells blocks the in vitro and in vivo differentiation of the cells. In particular, embryoid bodies produced from these Pgk-Pem ES cells do not differentiate into primitive endoderm or embryonic ectoderm, which are prominent features of early embryoid bodies from normal ES cells. This Pgk-Pem phenotype is also different from the null phenotype, as embryoid bodies derived from ES cells in which endogenous Pem gene expression has been blocked show a pattern of differentiation similar to that of normal ES cells. When the Pgk-Pem ES cells were introduced into subcutaneous sites of nude mice, only undifferentiated EC-like cells were found in the teratomas derived from the injected cells. The Pem-dependent block of ES cell differentiation appears to be cell autonomous; Pgk-Pem ES cells did not differentiate when mixed with normal, differentiating ES cells. A block to ES cell differentiation, resulting from the forced expression of Pem, can also be produced by the forced expression of the nonhomeodomain region of Pem. These studies are consistent with a role for Pem in regulating the transition between undifferentiated and differentiated cells of the early mouse embryo.

Animals↗

PubMed1999

UV irradiation upregulates Egr-1 expression at transcription level.

UVC irradiation rapidly and strongly induces protein expression of the early growth response-1 gene (Egr-1) encoding a transcription factor which may have a protective function against UV damage. In this paper, we further investigate mechanisms responsible for such induction. We show that UVC irradiation also induced Egr-1 mRNA expression, increased transcription rate by nuclear run-on assay and stimulated Egr-1 promoter activity by CAT assay. The Egr-1 mRNA stability remained unchanged in UVC-treated cells. On the other hand, UVC irradiation slightly extended Egr-1 protein half-life. The induction of Egr-1 by UVC was observed in many different cell types. UVA and UVB also strongly induced Egr-1 expression. These results indicate that UVC regulates Egr-1 expression at transcription level. The induction pattern of Egr-1 by UV suggests the importance of Egr-1 in the UV response.

3T3 Cells↗

PubMed1999

Germline hMSH2 and differential somatic mutations in patients with Turcot's syndrome. Genes Chromosomes Cancer 25:75-81, 1999.

Chan TL, Yuen ST, Chung LP, Ho JWC, Kwan K, Fan YW, Chan ASY, Leung SY. 1999. Germline hMSH2 and differential somatic mutations in patients with Turcot's syndrome. Genes Chromosomes Cancer 25:75-81, 1999. It has come to our attention that the three patients described in the article above, were also included in a report by Leung et al., American Journal of Pathology, 153:1181-1189, 1998. Reference to the American Journal of Pathology article was inadvertently omitted

Journal Article↗

PubMed1999

IFN-gamma knockout mice show Th2-associated delayed-type hypersensitivity and the inflammatory cells fail to localize and control chlamydial infection.

Delayed-type hypersensitivity (DTH) has been demonstrated to be a Th1 type immune response which is important in the host defense against infection with intracellular bacteria, including Chlamydia. In the present study, we surprisingly observed that C. trachomatis mouse pneumonitis MoPn-infected IFN-gamma gene knockout (KO) mice mounted strong DTH responses following foopad challenge with inactivated organisms. The DTH responses in IFN-gamma KO mice were associated with Th2 cytokine production and partially blocked by anti-IL-4 monoclonal antibodies. In addition, the inflammatory cells in IFN-gamma KO mice failed to target the cellular sites of chlamydial inclusions in infected tissues and failed to clear the infection. The data, in conjunction with previous studies, suggest that different types (Th1 and Th2 associated) of DTH responses may function differently in host defense against chlamydial infection and that the functional differences in DTH responses may account for the dual role that DTH is speculated to play in chlamydial protective immunity and immunopathology. Moreover, the data suggest that the IFN-gamma KO mouse is a useful model system for studying chlamydial pathogenesis.

Animals↗

PubMed1999

Application of capillary nongel sieving electrophoresis for gene analysis.

Capillary electrophoresis (CE) has proved to be a strong tool for DNA analysis and has found abundant applications in the fields of restriction fragment sizing, mutation screening, polymerase chain reaction (PCR) product characterizing and forensic identifying. CE may be the main alternative to slab gel electrophoresis. Capillary nongel electrophoresis is the most favorable mode when aiming for this purpose because of its advantages of long lifetime, easy operation, good reproducibility, and low expense. In this paper, a new kind of sieving matrix, with mannitol as the additive for capillary electrophoresis, as well as related methods and their application for gene analysis were reported. Nine DNA fragments amplified by multiplex PCR from a normal dystrophin gene were well separated by this system. Three different deletions were found in Duchenne muscular dystrophy (DMD) patients. Three to four copies of the sex-determination region of the Y chromosome (SRY) gene, as well as the phenylalanine hydroxylase (PAH) gene, could be detected in mixed samples. The frequencies of short tandem repeats (STR) in PAH genes was analyzed in 61 normal Chinese individuals and 6 phenylketonuria families. One case of prenatal gene diagnosis was performed. By using this matrix, CE coupled with reverse transcription PCR (RT-PCR), the analysis of the alternative splicing expression pattern of the fragile X mental retardation 1 (FMR1) gene in adult lung tissue was achieved.

Adult↗

PubMed1999

Drosophila melanogaster sex peptide stimulates juvenile hormone synthesis and depresses sex pheromone production in Helicoverpa armigera.

Previous studies demonstrate that virgin female adult Helicoverpa armigera (Lepidoptera: Noctuidae) moths exhibit calling behaviour and produce sex pheromone in scotophase from the day after emergence, and that mating turns off both of these pre-mating activities. In the fruit fly Drosophila melanogaster, a product of the male accessory glands, termed sex peptide (SP), has been identified as being responsible for suppressing female receptivity after transfer to the female genital tract during mating. Juvenile hormone (JH) production is activated in the D. melanogaster corpus allatum (CA) by SP in vitro. We herein demonstrate cross-reactivity of D. melanogaster SP in the H. armigera moth: JH production in photophase virgin female moth CA in vitro is directly activated in a dose-dependent manner by synthetic D. melanogaster SP, and concurrently inhibits pheromone biosynthesis activating neuropeptide (PBAN)-activated pheromone production by isolated pheromone glands of virgin females. Control peptides (locust adipokinetic hormone, AKH-I, and human corticotropin, ACTH) do not inhibit in vitro pheromone biosynthesis. Moreover, SP injected into virgin H. armigera females, decapitated 24 h after eclosion, or into scotophase virgin females, suppresses pheromone production. In the light of these results, we hypothesize the presumptive existence of a SP-like factor among the peptides transmitted to female H. armigera during copulation, inducing an increased level of JH production and depressing the levels of pheromone produced thereafter.

Journal Article↗

PubMed1999

Cloning and tissue expressional characterization of a full-length cDNA encoding human neuronal protein P17.3.

A full-length cDNA of 595 bp was isolated from a human fetal brain cDNA library. It contains an open reading frame encoding 153 amino acids, with an 18-bp 5'UTR and a 118-bp 3'UTR in which there is an atypical polyadenylation signal (ATTAAA). The calculated molecular weight of the deduced protein is 17.3 kU. The predicted isoelectric point is 4.89. On account of its high homology to mouse neuronal protein NP15.6 (81.2% identity), the deduced protein was named neuronal protein 17.3 (NP17.3). When its secondary structure was examined by the GGBSM program of PCGENE software, it was found that 32.6 and 15.0% of its amino acids are involved in forming alpha-helices and beta-sheets, respectively. Examined with the PESTFIND program, a typical PEST region found in rapidly degraded proteins was found between residue 48 and residue 68.

5' Untranslated Regions↗

PubMed1999

Systemic mycobacterial infection inhibits antigen-specific immunoglobulin E production, bronchial mucus production and eosinophilic inflammation induced by allergen.

As the burden of infectious diseases becomes reduced in many countries, a remarkable increase in the incidence of allergies has occurred. The basis for the rise in atopic disorders as a correlate of the decline in infectious diseases has not been defined. In the present study, we tested experimentally whether prior systemic infection with Mycobacterium bovis bacillus Calmette Guérin (BCG) had any effect on ovalbumin (OVA) Al(OH)3 (alum)-induced immunoglobulin E (IgE) production, airway mucus production and eosinophilic inflammation. The data showed that allergen-specific IgE production and OVA-induced eosinophilia and goblet cell development were significantly inhibited by prior infection with BCG. Correspondingly, following immunization with OVA alum, BCG-infected mice exhibited significantly higher levels of allergen-driven interferon-gamma (IFN-gamma) production than the mice without infection. The ratio of IFN-gamma: interleukin (IL)-4 production was higher in OVA-sensitized mice with prior BCG infection than in those without infection. The abrogation of OVA-induced mucus production and pulmonary eosinophilia in BCG-infected mice correlated with significantly decreased IL-5 production and increased IFN-gamma and IL-12 production. These data provide direct evidence that intracellular bacterial infection (i.e. BCG) can inhibit antigen-specific IgE and airway reactivity induced by environmental allergen. Furthermore, the results suggest that changes in cytokine-producing patterns of T lymphocytes and other cells may be the mechanism by which infections influence allergies.

Allergens↗

PubMed1999

Tumor promotion by hydrogen peroxide in rat liver epithelial cells.

Reactive oxygen species, including H2O2, play an important role in the tumor promotion process. Using an in vitro model of tumor promotion involving the rat liver epithelial oval cell line T51B, the tumor promoting activity of H2O2 in N-methyl-N'-nitro-N-nitrosoguanidine-initiated cells was studied. In this assay system, the promoting effect of H2O2 is evidenced by the formation of colonies in soft agar, appearance of foci in monolayer culture, disruption of gap junction communication (GJC) in foci areas and growth at higher saturation densities. H2O2 preferentially induced the expression of c-fos, c-jun, c-myc and egr-1, while JunB and JunD levels remained almost unchanged. H2O2 also induced hyperphosphorylation of Cx43 and disruption of GJC. The effects of H2O2 on tumor promotion, induction of immediate early (IE) genes and disruption of GJC are blocked by antioxidants. These results suggest that H2O2 acts as a tumor promoter in rat liver non-neoplastic epithelial cells and that the induction of IE genes and disruption of GJC are two possible targets of H2O2 during the tumor promotion process.

Animals↗

PubMed1999

Chlamydia trachomatis (mouse pneumonitis strain) induces cardiovascular pathology following respiratory tract infection.

Chlamydia, especially Chlamydia pneumoniae, infection is closely associated with human cardiovascular diseases. Thus far, however, few experimental studies have been carried out to investigate whether natural C. trachomatis infection can induce cardiovascular pathological changes. In this article, we report that pulmonary infection with C. trachomatis mouse pneumonitis strain (MoPn) can induce myocardial and perivascular inflammation and fibrosis in C57BL/6 mice. The pulmonary MoPn infection appeared to be disseminated systemically, because chlamydial antigens were readily detectable in multiple organs including the cardiovascular tissues. In addition, gamma interferon gene knockout mice with a C57BL/6 genetic background showed significant endocarditis and pancarditis characterized by vegetation in aortic valves, interstitial and pericardial inflammatory cellular infiltration, and growth of the organisms in the heart following respiratory tract MoPn infection. The results indicate that C. trachomatis can induce cardiovascular diseases following respiratory tract infection and suggest that murine MoPn respiratory tract infection may be a useful experimental model for investigating cardiovascular diseases caused by chlamydial infection.

Animals↗