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Biomedical subjects

Y Fan

Publications and source records attributed to Y Fan.

At least 109 records · Page 6Linked to original sources
PubMed1998

Multiple forms of GnRH are released from perifused medial basal hypothalamic/preoptic area (MBH/POA) explants in birds.

Both chicken gonadotropin-releasing hormones I and II (cGnRH I and II) were detected in abundant quantity by radioimmunoassay of extracts of Japanese quail medial basal hypothalamic/preoptic area (MBH/POA) fragments that included the median eminence (ME) region. However, in radioimmunoassayed extracts of Japanese quail ME alone, the concentration of cGnRH I greatly exceeded that of cGnRH II (approximately 450 pg/ME vs < 10 pg/ME). Likewise, cGnRH I and II were released into perifusates from quail an turkey MBH/POA explants maintained in short-term perifusion. Release of both forms occurred whether or not explants included the ME region, i.e., from quail POA explants did not include the ME or from turkey MBH/POA explants from which the ME region had been dissected out. This indicates that neuropeptides released from areas other than the ME can be a major source of neuropeptides detected in perifusates. Further, release of cGnRH I was altered following the addition of norepinephrine to perfusion media, whereas cGnRH II release was unaffected, again, whether or not explants included the ME. These results demonstrate that the release of neurohemoral substances from perifused explants cannot be assumed to represent regulated secretion from the ME.

Animals↗
PubMed1998

Egr-1 inhibits apoptosis during the UV response: correlation of cell survival with Egr-1 phosphorylation.

UV irradiation of normal or immortalized cells induces a rapid increase in the expression of several transcription factors and is thought to serve a protective function. The human fibrosarcoma cell line, HT1080 clone H4, expresses almost undetectable levels of Egr-1 and does not respond to UV-C irradiation by the induction of Egr-1. The H4 cells are hypersensitive to UV which induces apoptosis and reduces clonogenicity. The introduction of exogenous Egr-1 into H4 (H4E9 and H4E4 cell-lines) confers protection from UV damage as measured by a number of assays. In both NIH3T3 (with inducible Egr-1) and H4E9 (constitutive Egr-1) cells, UV irradiation gave enhanced transactivation of Egr-1 reporters that correlated with phosphorylated Egr-1. Studies using inhibitors indicated that protein kinase-C and tyrosine kinases are involved in the anti-apoptotic effects of Egr-1 after UV damage. This is the first description of a biological effect of phosphorylated Egr-1.

3T3 Cells↗
PubMed1998

Mining the National Cancer Institute Anticancer Drug Discovery Database: cluster analysis of ellipticine analogs with p53-inverse and central nervous system-selective patterns of activity.

The United States National Cancer Institute conducts an anticancer drug discovery program in which approximately 10,000 compounds are screened every year in vitro against a panel of 60 human cancer cell lines from different organs. To date, approximately 62,000 compounds have been tested in the program, and a large amount of information on their activity patterns has been accumulated. For the current study, anticancer activity patterns of 112 ellipticine analogs were analyzed with the use of a hierarchical clustering algorithm. A dramatic coherence between molecular structures and their activity patterns could be seen from the cluster tree: the first subgroup (compounds 1-66) consisted principally of normal ellipticines, whereas the second subgroup (compounds 67-112) consisted principally of N2-alkyl-substituted ellipticiniums. Almost all apparent discrepancies in this clustering were explainable on the basis of chemical transformation to active forms under cell culture conditions. Correlations of activity with p53 status and selective activity against cells of central nervous system origin made this data set of special interest to us. The ellipticiniums, but not the ellipticines, were more potent on average against p53 mutant cells than against p53 wild-type ones (i.e., they seemed to be "p53-inverse") in this short term assay. This study strongly supports the hypothesis that "fingerprint" patterns of activity in the National Cancer Institute in vitro cell screening program encode incisive information on the mechanisms of action and other biological behaviors of tested compounds. Insights gained by mining the activity patterns could contribute to our understanding of anticancer drugs and the molecular pharmacology of cancer.

Antineoplastic Agents↗
PubMed1998

The Polycomb group in Caenorhabditis elegans and maternal control of germline development.

Four Caenorhabditis elegans genes, mes-2, mes-3, mes-4 and mes-6, are essential for normal proliferation and viability of the germline. Mutations in these genes cause a maternal-effect sterile (i.e. mes) or grandchildless phenotype. We report that the mes-6 gene is in an unusual operon, the second example of this type of operon in C. elegans, and encodes the nematode homolog of Extra sex combs, a WD-40 protein in the Polycomb group in Drosophila. mes-2 encodes another Polycomb group protein (see paper by Holdeman, R., Nehrt, S. and Strome, S. (1998). Development 125, 2457-2467). Consistent with the known role of Polycomb group proteins in regulating gene expression, MES-6 is a nuclear protein. It is enriched in the germline of larvae and adults and is present in all nuclei of early embryos. Molecular epistasis results predict that the MES proteins, like Polycomb group proteins in Drosophila, function as a complex to regulate gene expression. Database searches reveal that there are considerably fewer Polycomb group genes in C. elegans than in Drosophila or vertebrates, and our studies suggest that their primary function is in controlling gene expression in the germline and ensuring the survival and proliferation of that tissue.

Amino Acid Sequence↗
PubMed1998

[Improving the bonding strength of castable ceramic crowns].

To study the influence of bonding agent on fracture strength of Plat-II castable ceramic crowns bonded to molars, we tested the specimens in vitro with Panavia 21 resin bonding agent and porcelite dual cure cement. The results showed that the fracture loading (845.8 +/- 137.1 N) of crowns bonded with Panavia 21 bonding agent was higher than that (534.0 +/- 58.7 N) of crows bonded with porcelite dual cure cement. The difference between the two agents was statistically significant (P < 0.05). The crowns bonded with Panavia 21 agent had higher strength than bite forces. These suggest that costable ceramic crowns could be bonded with Panavia 21 resin agent in clinical practice.

Crowns↗
PubMed1998

[Pulmonary complications occurring after allogeneic bone marrow transplantation].

OBJECTIVE: To explore the risk factors for and pathogenesis of pulmonary complications (PC) occurred after allogeneic bone marrow transplantation (allo-BMT). METHODS: The PC in 185 patients undergone allo-BMT were analyzed. RESULTS: Ninety-three PC episodes were observed in 89 patients and most of them were due to infections, including bacterial pneumonia (n = 27), interstitial pneumonia (n = 7), pulmonary fungus disease (n = 16), tuberculosis (n = 4), obstructive lung disease (n = 2), pulmonary edema (n = 2), lung abscess (n = 1) and 34 episodes caused by two or more pathogens. The overall mortality for PC was 12.43% (23/185). CONCLUSION: The risk factors for PC occurred after allo-BMT were not related to age and sex of recipients, bone marrow status before BMT, conditioning regimen and pulmonary function. Graft-versus-host-disease significantly increased the morbidity and mortality of PC after allo-BMT.

Acute Disease↗
PubMed1998

[Polymerase chain reaction technique in monitoring treatment of bacillary pulmonary tuberculosis].

OBJECTIVE: To explore the relationship between sputum Mycobacterium tuberculosis as well as its DNA negative conversion and relapse in bacillary pulmonary tuberculosis during chemotherapy and 2 years after completion of treatment, and to evaluate the value of polymerase chain reaction (PCR) technique in monitoring the efficacy of treatment. METHOD: Eighty-seven patients with bacillary pulmonary tuberculosis were monthly examined by PCR technique, smear and culture methods, and were followed up for 2 years after treatment. RESULT: The duration of sputum negative conversion by PCR technique was 1-3 months later than that by smear and culture methods. The more the sputum bacteria, the longer the duration of PCR positive results. Positive PCR results maintained in 10 out of 87 patients for more than 1 year, among them 3 (30%) relapsed respectively at 8, 12 and 16 months after treatment. One PCR negative conversion case relapsed at 18 months after treatment. These 4 cases who regained sputum positive results and showed deterioration in chest X-ray films were admitted to hospital again. CONCLUSION: PCR technique is more practical than smear and culture methods in monitoring efficacy of the treatment of bacillary pulmonary tuberculosis, and is useful for evaluating cases with possible relapse.

Adult↗
PubMed1998

[Seasonal and sexual variety of Ginkgo flavonol glycosides in the leaves of Ginkgo biloba L].

HPLC methods have been developed for the determination of Ginkgo flavonol glycosides in the Ginkgo biloba leaves obtained from May to November in the fallen leaves and in the leaves obtained from female and male trees. The method includes hydrolysis of the leaves and subsequent quantitative chromatographic assay of the aglycones, followed by calculation of Ginkgo flavonol glycosides content. The result shows that the leaves obtained in May have the highest content of 0.96%, and then the content decreases from May to August, and from August to November remains almost the same, that is 0.5% also. Fallen leaves have the lowest content of 0.44%. The content range is 0.96% to 0.44%. Male trees have higher content of glycosides than female trees.

Chromatography, High Pressure Liquid↗
PubMed1998

[Endovascular treatment of carotid-cavernous sinus fistulae].

OBJECTIVE: To treat carotid-cavernous sinus fistulae mmunications between 43 patients with endovascular procedure. METHOD: Of the 43 patients 37 were male and 6 female. Traumatic and spontaneous CCF were noted in 39 and 4 patients respectively. 36 patients with CCF were given ICA alone, both internal and external carotid arteries in 7. Fistulae occlusion in 31 patients and ICA obliteration in 12 patients were achieved with transarterial detachable balloon technique. External carotid feeding arteries were embolized with silk suture in 7 patients. RESULT: Angiographic and clinical cure wer obtained in 39 patients and improved in 4. One patient was complicated by hemiplegia postoperatively. CONCLUSION: Endovascular balloon embolization is the first method of choice in dealing with carotid-cavernous fistulae.

Adolescent↗
PubMed1998

[A quick algorithm for detecting macro-particles distributed rarefiedly].

This paper presents a simple and quick algorithm, based on the principle of OR operation, for detecting macro-particles when the distribution of macro-particled is few and scattered. Counting and measuring the basic size parameters of macro-particles will be simultaneously accomplished by scanning the macroparticle image only once time.

Algorithms↗
PubMed1998

[A methodological study on the detection of myocardial ultrasonic integrated backscatter].

The cyclic fluctuation of ultrasonic integrated backscatter(IB) of myocardium has been found to be a potential indicator of clinical significance in the diagnosis of myocardial ischemia. To investigate the feasibility of such a technique, a clinical IB testing system is established in our laboratory. Six male subjects with no history of heart diseases were tested by using this system. Based on the clinical data obtained during the tests, the effects of echo position, bandwidth, and different calculation algorithms on IB value were analyzed and compared. The results are available to provide a guideline for the design of instrumentation for IB detection.

Adult↗
PubMed1998

[A study of non-steady flow properties in flow chamber experiment].

A time-dependent velocity equation has been achieved by means of eigenfunction method in this paper, which can satisfy any impetus and describe the changing process from the initial time to any time. The theoretical basis is provided to study the nature of blood cells in non-steady flow.

Nonlinear Dynamics↗
PubMed1998

Detection of germ cell tumor cells in apheresis products using polymerase chain reaction.

The contamination of apheresis products with tumor cells was evaluated in patients undergoing autologous peripheral blood stem cell transplantation for germ cell tumors. A blinded, retrospective analysis was performed on 63 apheresis products from 28 patients using the PCR and primers for beta human chorionic gonadotropin (beta-HCG). Of the 20 patients with beta-HCG-secreting tumors, 8 apheresis products from 7 patients were PCR positive. PCR was negative in the 8 patients whose tumors did not secrete beta-HCG. Twenty-two apheresis products from patients with lymphoma and breast cancer were negative for beta-HCG expression. Evaluating the 20 patients with beta-HCG-secreting tumors, 100% of PCR-positive patients had elevated serum beta-HCG at the time of apheresis compared to 46.2% of PCR-negative patients (P = 0.04). A positive PCR was also associated with a higher serum beta-HCG at diagnosis (P = 0.03). Patients receiving a PCR-positive product had a higher relapse rate (85.7 versus 61.5%) and were more likely to have visceral metastasis (100 versus 61.5%), although the numbers did not reach statistical significance (P = 0.35 and 0.11, respectively). The finding of beta-HCG mRNA in apheresis products strongly suggests the presence of circulating tumor cells in a significant number of germ cell patients undergoing autologous transplantation. This assay may be useful in monitoring attempts at tumor cell depletion and in developing improved prognostic models for assessing risk of relapse after transplantation.

Blood Component Removal↗
PubMed1998

Regulation of callus status and cell-suspending culture in naked seed oat (Avena nuda).

The original calli were obtained by inducing culture of mature embryos of naked seed oat on N6 medium. The original calli were white-colored tumor forms, soft outside and hard inside. These kinds of calli are easy to differentiate into plantlets, and they are not the friable type. Friable embryogenic calli could be obtained by cycled regulated culture on IM1-IM4 medium for 7-8 months from the original calli. They became vigorous, lightish yellow in color, with small grainy forms. Well-separated and fast-growing suspending cell lines have been obtained from the above-mentioned embryogenic calli in the liquid medium. Regenerated plants have been obtained for this kind of suspension line by culturing on the medium for differentiation. The surviving percentage for such plantlets was over 95% after planting in the soil.

Avena↗
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↗