Search PubMed⌕ Search

Biomedical subjects

Y Fan

Publications and source records attributed to Y Fan.

At least 127 records · Page 7Linked to original sources
PubMed1998

Rectification on the inertial effects for co-axial cylinders rheometer.

The inertia of the fluid and the inner cylinder in co-axial cylinders rheometer have a great influence on the unsteady flow of non-Newtonian fluid. In the paper this phenomenon is studied minitely and a method to correct the measured results for an unsteady flow in the rheometer is proposed. It was found that the inertia effect of a fluid can be ignored when the gap between cylinders is smaller and the inertia effect of the inner cylinder can be represented with a vibration equation. Using the equation changes of Huang's blood constitutive parameters are observed.

Hemorheology↗
PubMed1997

Reciprocal modulation between Sp1 and Egr-1.

Many ubiquitously expressed genes, including oncogenes, lack a proximal TATA or CAAT box but have a region of G + C-rich sequences that appears to replace the usual promoter initiation site. The zinc-finger protein Sp1 is one of the prevalent activators of these genes. The Egr-1 zinc-finger protein has a similar binding site and if the two sites occur in the same region, a variety of activation or inhibitory responses may be obtained. We show that competition between the two factors for overlapping sites on growth-promoting genes could explain why the overexpression of Egr-1 suppresses transformed growth in a number of cell types [Huang et al. (1995): Cancer Res 55:5054-5062; Huang et al. (1997): Int J Cancer]. We demonstrate here that Egr-1 and Sp1 can bind to the same G + C-rich sites and that Egr-1 can displace Sp1 and hence inhibit its activity. We measured the responses of synthetic consensus binding sites and natural promoter sequences linked to a reporter gene and showed that Egr-1 inhibited the activation of transcription by Sp1 on overlapping Sp1/Egr-1 sites. In contrast, Sp1 activity could be augmented by Egr-1 at nonoverlapping sites in the Egr-1 gene promoter, in transient reporter gene studies in Drosophila SL2 cells. In addition, over-expression of exogenous Sp1 in mammalian cells, also leads to increased Egr-1 protein expression, which further inhibits Sp1 transactivation of numerous genes. Therefore, we can account for some of the complex responses of G + C-rich enhancer/promoters by a form of "facilitated inhibition" of Sp1 by Egr-1 at overlapping sites.

3T3 Cells↗
PubMed1997

Antitumor activity and immunotherapeutic properties of Flt3-ligand in a murine breast cancer model.

Flt3-Ligand (Flt3-L) is a stimulatory cytokine for a variety of hematopoietic lineages, including dendritic cells and B cells. The antitumor properties of Flt3-L were evaluated in C3H/HeN mice challenged with the syngeneic C3L5 murine breast cancer cell line. Eighty % of animals receiving 500 microg/kg/day of Chinese hamster ovary-derived human Flt3-L for 10 days were protected from tumor growth, whether the tumor challenge was administered on the first or fourth days of Flt3-L administration. The protection provided by soluble Flt3-L was transient. All tumor-free animals rechallenged 4 weeks after the primary challenge developed tumor. Transduction of C3L5 with retroviral vectors expressing human or murine Flt3-L did not influence in vitro growth or MHC expression but decreased in vivo tumor development to 0 and 10% of mice, respectively. This compares with tumor growth of 52% with interleukin-2 transduced C3L5 and over 85% with untransduced and control vector-transduced C3L5. Unlike animals treated with soluble Flt3-L, administration of Flt3-L as a tumor vaccine protected mice from a subsequent challenge with untransduced C3L5 in 60-78% of mice, compared to 0% of controls. Our initial work used the most common Flt3-L isoform, which is membrane bound but can undergo proteolytic cleavage to generate a soluble form. To evaluate the role of the various Flt3-L isoforms in preventing tumor formation, retroviral vectors encoding only the membrane-bound form or only the soluble isoform were evaluated in the C3L5 model. Tumor formation was similar with either isoform, preventing tumor formation in 80-90% of mice after the primary challenge and 88-89% after the secondary challenge. Splenocytes obtained 4 weeks after the secondary challenge conferred adoptive immunity to naive mice in 60% of animals. This initial report of antitumor activity by Flt3-L is consistent with its known stimulatory effect on antigen-presenting cells and suggests it may enhance the development of tumor vaccines.

Adoptive Transfer↗
PubMed1997

Decreased Egr-1 expression in human, mouse and rat mammary cells and tissues correlates with tumor formation.

We have examined several types of tumor cell lines and shown that they invariably expressed little or no Egr-1, in contrast to their normal counterparts. We have previously shown that the expression of exogenous Egr-1 in human breast and other tumor cells markedly reduces transformed growth and tumorigenicity. We therefore hypothesized that the loss of Egr-1 expression plays a role in transformation. All human and mouse breast cancer cell lines and tumors examined had reduced Egr-1 expression compared with their normal counterparts. Reduced Egr-1 expression was also observed in 7,12-dimethylbenz(a)anthracene (DMBA)-induced rat mammary tumors, and this level increased to normal levels in tumors that regressed after tamoxifen treatment. We concluded, therefore, that loss of Egr-1 expression may play a role in the deregulation of normal growth in the tumorigenic process and that Egr-1 acts as a tumor suppressor gene.

Animals↗
PubMed1997

Reduced expression of mismatch repair genes measured by multiplex reverse transcription-polymerase chain reaction in human gliomas.

Microsatellite instability (MIN) is frequently observed in hereditary nonpolyposis colon cancer and in other sporadic cancers including gliomas. Abnormalities in at least one of five mismatch repair (MMR) genes are implicated in the development of cancers in hereditary nonpolyposis colon cancer and the associated MIN. Using a newly developed multiplex reverse transcription-PCR assay, we evaluated the expression of the five known human MMR genes (hMSH2, hMLH1, hPMS1, hPMS2, and GTBP) in human gliomas by measuring simultaneously the relative levels of the transcripts. The beta-actin gene was used as an internal control for RNA degradation and DNA contamination and as a reference for quantifying the levels of their transcripts. Of the 33 gliomas examined, 42% (14) had low expression of hMSH2 (at least 4-5-fold lower than normal mean), 21% (7) had low expression of hMLH1, and 18% (6) had low expression of hPMS1 compared with the expression in the lymphocytes from 13 normal individuals. Furthermore, six of the 33 (18%) tumor samples had decreased expression of more than one MMR gene. Two of these six patients with multiple gene abnormalities had second primary cancers, and an additional patient had multifocal gliomas. Further molecular analysis of available DNA samples indicated that one of five of those tumors with aberrant expression of MMR genes had MIN, as compared with none of five tumors with normal expression. These data suggest that reduced expression of MMR genes is frequent in human gliomas and that aberrant expression of more than one MMR gene may be associated with increased risk of second primary malignancies in glioma patients.

Adaptor Proteins, Signal Transducing↗
PubMed1997

Altered hematopoiesis, behavior, and sexual function in mu opioid receptor-deficient mice.

The mu opioid receptor is thought to be the cellular target of opioid narcotics such as morphine and heroin, mediating their effects in both pain relief and euphoria. Its involvement is also implicated in a range of diverse biological processes. Using a mouse model in which the receptor gene was disrupted by targeted homologous recombination, we explored the involvement of this receptor in a number of physiological functions. Mice homozygous for the disrupted gene developed normally, but their motor function was altered. Drug-naive homozygotes displayed reduced locomotor activity, and morphine did not induce changes in locomotor activity observed in wild-type mice. Unexpectedly, lack of a functional receptor resulted in changes in both the host defense system and the reproductive system. We observed increased proliferation of granulocyte-macrophage, erythroid, and multipotential progenitor cells in both bone marrow and spleen, indicating a link between hematopoiesis and the opioid system, both of which are stress-responsive systems. Unexpected changes in sexual function in male homozygotes were also observed, as shown by reduced mating activity, a decrease in sperm count and motility, and smaller litter size. Taken together, these results suggest a novel role of the mu opioid receptor in hematopoiesis and reproductive physiology, in addition to its known involvement in pain relief.

Animals↗
PubMed1997

Retroviral gene therapy in hematopoietic diseases.

A number of diverse gene therapy strategies are being evaluated in the search for novel therapeutic approaches to hematopoietic disease. In this review, we will limit our discussion to three areas of active research: the treatment of genetic diseases, the use of drug resistance gene vectors in autologous transplantation, and tumor immunization strategies in cancer. Although gene delivery remains a major challenge to gene therapy, recent modifications which improve gene transfer will also be addressed.

Genetic Therapy↗
PubMed1997

Percutaneous vasal sperm aspiration and intrauterine insemination in the treatment of obstructive azoospermia.

OBJECTIVE: To treat obstructive azoospermia by using sperm recovered from percutaneous vasal sperm aspiration in IUI. DESIGN: Clinical study. SETTING: Institutional clinic in Jinan. PATIENT(S): Six men with obstructive azoospermia, three of whom were treated with percutaneous vasal sperm aspiration and IUI; sperm recovered from this procedure were used for IUIs. INTERVENTION(S): Spermatozoa used for intrauterine injection were retrieved by percutaneous vasal sperm aspiration and incubated at 37 degrees C for 40 to 60 minutes. MAIN OUTCOME MEASURE(S): Normal pregnancy. RESULT(S): Intrauterine insemination was performed in three patients for one or two cycles, with motile spermatozoa. There was one successful term delivery. CONCLUSION(S): Percutaneous vasal sperm aspiration can be used successfully to recover sperm in men with obstructive azoospermia for use in IUI. The technique is simple and less traumatic than an open surgical procedure.

Female↗
PubMed1997

The 30/35 kDa chymotryptic fragment of fibronectin enhances retroviral-mediated gene transfer in purified chronic myelogenous leukemia bone marrow progenitors.

We have previously shown by reverse transcriptase-PCR (rtPCR) that CML CD34+ HLA-DR- cells are enriched for BCR/ABL(-) hematopoietic progenitor cells (HPC) while leukemic HPC reside predominately within CML CD34+ HLA-DR+ cells. We investigated whether the 30/35 kDa fragment of fibronectin (FN) could be used to enhance retroviral-mediated gene transfer (RMGT) in chronic phase CML marrow HPC. CML CD34+ HLA-DR- and CD34+ HLA-DR+ cells were transduced with vector supernate containing the neomycin resistance gene on plates coated with either FN or bovine serum albumin (BSA) as control, then assayed for transduced HPC in progenitor cell assays in the presence or absence of G418. Transduction efficiency of CML CD34+ HLA-DR- cells over BSA ranged from 0.09 to 7.2% (mean 3.3 +/- 1.5%), while that over FN plates ranged from 3.8 to 23% (mean 11.0 +/- 4.5%) (n = 4). Transduction efficiencies of CML CD34+ HLA-DR+ cells ranged from 0.4 to 9.8% (mean 3.7 +/- 1.7%) and 6.0 to 26% (mean 17.3 +/- 4.5%) (n = 5) over BSA and FN, respectively. rtPCR analysis for BCR/ABL mRNA of individual G418-resistant HPC generated from CD34+ HLA-DR- cells revealed that normal BCR/ABL(-) HPC were successfully transduced under these experimental conditions. These results demonstrate the feasibility of transducing normal CML primitive HPC, and illustrate the potential clinical use of FN in the setting of gene therapy for CML, as well as other diseases.

Adult↗
PubMed1997

[Thin split thickness skin grafting double taken from avulsed skin in treatment for skin avulsion in children].

In order to utilize avulsed skin to cover skin defects, a new skin grafting technique, thin split thickness skin grafting double taken from avulsed skin, was used in 23 cases of severe skin avulsion. The skin grafts in profound layer were observed histologically. The results showed no difference between skin grafts in superficial layer and ones in profound layer, but the latter needed longer time to heal. Using this technique, we can obtain skin graft in double amount from avulsed skin.

Adolescent↗
PubMed1997

[Alternative splicing of the FMR1 gene in human fetal tissues].

OBJECTIVE: To gain more insight into biological role of the alternative splicing of the FMR1 gene, isoforms of the FMR1 mRNA from human fetal heart, spleen, liver and kidney were analyzed. METHODS: RNAs were isolated from the tissues of an abortion fetus (approximately 6 months postconception). Alternative splicing patterns of the FMR1 mRNA were analyzed by RT-PCR and cloning strategy. RESULTS: One isoform of the FMR1 mRNA was found to be dominant in all of the four tissues. The major isoform was as same as the dominant one in the fetal cortex but was different from the major isoform in adult brain. The difference between the major isoforms in the fetal tissues and adult brain was the splicing out or retaining the peptide encoded by exon 12 and exon 17. CONCLUSION: This result suggested a developmental switch of alternative splicing of the FMR1 gene. The difference between the major isoforms in the fetal tissues and adult brain suggested the two peptides may have special roles in related developmental stages.

Alternative Splicing↗
PubMed1997

[The compressive strength, tensile strength, flexural strength and micro-hardness of Plat-II Castable Ceramics].

In preparation for the clinical use of Plat-II Castable Ceramics (PCC-II), we tested its compressive strength, tensile strength, flexural strength and microhardness. The flexural strength was tested by the three-point bending test. The result showed that the compressive strength was 541.7 MPa; the tensile strength 42.5 MPa; the flexural strength 142.0 MPa; the modulus of elasticity 61.4 GPa; and the micro-hardness 499.6 kg/mm3. The strength anol micro-hardness of PCC-II materials were better than those of human enamel. So PCC-II is applicable to restorations in dentistry.

Ceramics↗
PubMed1997

Biochemical changes in denervated muscle identified by magnetic resonance spectroscopy.

OBJECTIVE: Magnetic resonance spectroscopy (MRS) has the potential to noninvasively delineate early biochemical changes in denervated muscle. In this study, we examine metabolic changes in denervated rat facial muscles using quantitative invitro 1H and 31P MRS. METHODS: Forty male Wistar rats were subjected to transection of the facial nerve trunk on the left and sham exposure on the right, and allowed to recover. The animals were then reoperated at 1, 2, 4, or 8 weeks after the initial procedure. EMG of the facial muscles and facial nerve conduction studies were performed at both time points, and facial muscles were harvested from normal and control sides at the second procedure. Perchloric acid extracts of facial muscles were then prepared for analysis using MRS. RESULTS: The results showed a progressive time-dependent decrease in Cr, PCr, Pi, ATP, and ADP all on the transected side. CONCLUSION: This study is an important step in the development of clinically relevant noninvasive methods of assessing and quantifying degeneration in nerve-muscle systems.

Adenosine Diphosphate↗
PubMed1997

[Screening and genetic analysis of fragile X syndrome in Tongling Anhui province of China].

OBJECTIVE: To investigate the prevalence of fragile X syndrome in the Chinese. METHODS: Fragile X syndrome was screened from 172,600 people living in Tongling city, Anhui province. Suspected patients were tested by PCR and Southern Blotting. RESULTS: Seven of 88 mental handicap children were found with fra (X), including 3 female and 4 male patients. Six patients, 3 normal transmitting males and 5 carriers were found in detailed search in these 6 fra (X) families. Genetic linkage analyses of 2 of the families were reported here. CONCLUSION: The prevalence of fragile X syndrome in the Chinese is not apparently different from the previous reports on the Caucasian population.

Child, Preschool↗
PubMed1997

Cloning and sequencing of human thrombopoietin cDNA.

Human thrombopoietin (hTPO), a ligand for the protooncogene c-mpl, is the major humoral regulator of megakaryocytopoiesis and platelet production affecting the proliferation and maturation of committed cells. Recently the hTPO gene and cDNA were cloned from human genome and cDNA libraries. In this report, hTPO cDNA was synthesized by RT-PCR from a Chinese human fetal liver. The sequence of this cDNA showed a high homology with hTPO cDNA in the Genebank database (accession no. L36052) except that base substitution occurred at four sites (497, 595, 767, and 795 bp), which led to the change of three amino acid residues in the predicted protein.

Amino Acid Sequence↗
PubMed1997

[Relation between fetal intrauterine growth retardation and anticardiolipin antibodies].

OBJECTIVE: To investigate the relationship between fetal intrauterine growth retardation and anticardiolipin antibodies. METHODS: Serum anticardiolipin antibodies were detected with ELISA method in 5,330 cases of normal gravidas. Meanwhile, the observation of immunocomplex depositions in placentas in cases of positive anticardiolipin antibodies (ACA) were observed by immunofluorescence examination. RESULTS: The positive ACA rate in normal gravidas was 2.70%. The incidence of intrauterine growth retardation (IUGR) was 15.28% in cases of positive ACA, whereas was 1.77% in cases of negative ACA. There were significant differences between two groups (P < 0.001). Among children born in mothers with positive ACA, there were 5 cases of positive ACA. Immunocomplex depositions (Immunoglobulins & Complements) were all found in placenta of IUGR. CONCLUSIONS: ACA could be one of causes of IUGR. Determination of serum ACA would offer a new clue to diagnosis and treatment of IUGR.

Adult↗
PubMed1997

[Micro-particle image processing based on an artificial neuron network with fluid properties].

The form of macro-particle is a close successive region in two-valued micro-particle image, and the detection of microparticles is actually that of close successive regions. Accordign to this theory, this paper present a new technique for micro-particles detecting based on an artificial neuron network modeled on the diffusing behaviour of real visual system, which has fluid properties. The results of simulation on computer shew that this method is very effect.

Blood Cell Count↗