Sample records for aminopterin

  1. Time dependent inhibition of xanthine oxidase in irradiated solutions of folic acid, aminopterin and methotrexate

    International Nuclear Information System (INIS)

    The xanthine oxidase catalyzed oxidation of hypoxanthine was followed by monitoring the formation of uric acid at 290 nm. Inhibition of xanthine oxidase occurs in aqueous solutions of folic acid methotrexate and aminopterin. These compounds are known to dissociate upon exposure to ultraviolet light resulting in the formation of their respective 6-formylpteridine derivatives. The relative rates of dissociation were monitored spectrophotometrically by determining the absorbance of their 2,4-dinitrophenylhydrazine derivatives at 500 nm. When aqueous solutions of folic acid, aminopterin and methotrexate were exposed to uv light, a direct correlation was observed between the concentrations of the 6-formylpteridine derivatives existing in solution and the ability of these solutions to inhibit xanthine oxidase. The relative potency of the respective photolysis products were estimated

  2. Pseudoaminopterin syndrome. (United States)

    Kraoua, Lilia; Capri, Yline; Perrin, Laurence; Benmansour, Abdelmajjid; Verloes, Alain


    Pseudoaminopterin syndrome or aminopterin syndrome-like sine aminopterin (ASSA syndrome--OMIM 600325] is a rare autosomal recessive syndrome defined by characteristic dysmorphic features, skeletal defects, limb anomalies, cryptorchidism, and growth retardation. The syndrome owes its name to the fact that patients resemble the children exposed to aminopterin or to methotrexate, two dihydrofolate reductase inhibitors used for chemotherapy, or as an abortificient in early pregnancy. Ten patients have been described with pseudoaminopterin syndrome. Their phenotype is variable, and differs from the phenotype resulting from folic acid deprivation, leading to the notion that the pathogenesis may be more complex than simple vitamin deficiency. We report on an Algerian patient with pseudoaminopterin syndrome, review the previously reported cases and confirm that pseudoaminopterin syndrome does not result from a detectable contiguous gene imbalance as high resolution CGH array was normal in this child. PMID:22811276

  3. Tritiated thymidine and deoxycytidine suicide of mouse hemopoietic colony forming cells (CFC)

    International Nuclear Information System (INIS)

    Significant enhancement of tritiated dCyd suicide occurred when unlabelled dThd was added to cultures of mouse monocytic colony-forming cells. Incorporation experiments supported the suicide experiments in that incorporation of tritiated dCyd into DNA was significantly increased. One hundred micromolar dCyd significantly reduced the radiotoxicity of 0.3 μCi of tritiated dThd; incorporation experiments indicated a dose-related reduction in the incorporation of tritiated dThd into DNA with the addition of 1-100 μM unlabelled dCyd. The addition of 1 μM aminopterin reversed the effect of 100 μM deoxycytidine; viz., incorporation of dThd into DNA was 90% of controls. Aminopterin had a similar effect on deoxyuridine reversal of tritiated dThd incorporation into DNA. Aminopterin had no effect on the reduction of tritiated dThd incorporation into DNA due to the addition of 100 μM unlabelled thymidine. Unlabelled ribonucleosides, Urd and Cyd, did not significantly affect the suicide pattern of tritiated dThd or dCyd when they were added to CFC cultures. Unlabelled deoxyribonucleosides, dThd or dCyd, did not significantly affect the suicide pattern of either tritiated Cyd or Urd when they were added to cultures containing tritiated ribonucleosides. Unlabelled Urd or Cyd was effective in reversing the suicide due to tritiated Urd or Cyd. (author)

  4. Analogues of methotrexate in rheumatoid arthritis. 1. Effects of 10-deazaaminopterin analogues on type II collagen-induced arthritis in mice. (United States)

    DeGraw, J I; Colwell, W T; Crase, J; Smith, R L; Piper, J R; Waud, W R; Sirotnak, F M


    Carbonation of the dianions (LDA) of 5-methylthiophene-2-carboxylic, 2-methylpyridine-5-carboxylic, and 3-methylpyridine-6-carboxylic acids provided the respective carboxy heteroarylacetic acids. The crude diacids were directly esterified in MeOH-HCl to afford the diesters. Alkylation of the sodio anions with ethyl iodide yielded the appropriate alpha-ethyl diesters. The anions of the various diester substrates were then alkylated by 2,4-diamino-6-(bromomethyl)-pteridine followed by ester saponification at room temperature to afford the respective 2,4-diamino-4-deoxy-10-carboxy-10-deazapteroic acids. The 10-carboxyl group was readily decarboxylated by heating in DMSO at temperatures of 110-135 degrees C to give the diamino 10-deaza heteropteroic acid intermediates. Coupling with diethyl L-glutamate followed by ester hydrolysis afforded the target aminopterins. The analogues were evaluated for antiinflammatory effect in the mouse type II collagen model. The thiophene analogue of 10-ethyl-10-deazaaminopterin was found to be an effective inhibitor in terms of reduced visual evidence of inflammation and swelling as determined by caliper measurement. PMID:9022804

  5. Preparation and Preliminary Biological Evaluation of {sup 177}Lu-DOTA folate as Potential Folate Receptor Targeting Therapeutic Agent

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    Choi, Kang-Hyuk; Hong, Young-Don; Pyun, Mi-Sun; Lee, So-Young; Felipe, Fenelope; Yoon, Sun-Ha; Choi, Sun-Ju [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of)


    Folic Acid (FA) and FA derivatives are overexpressed on several tumor cells. The cell-membrane folic acid receptors are known to be responsible for the cellular accumulation of FA and FA analogs, such as methotrexate and folic acid. Folate has been characterized to have high affinity for the folate-receptor positive cells and tissues and considered to be useful as diagnostic imaging and therapeutic agent. In 1940s, Folate analogue, aminopterin, was first used for treatment of leukemia and recently, many folate derivatives were tried for cancer-treatment agent as well as visualization of folate receptor. Many researchers tried to conjugate folic acid with macromolecules or low molecular weight chelators through its alpha or gamma carboxylate. However, despite the reduced binding affinity, FAs are still recognized by the folate receptor. Therefore, we focused to develop folate-based radiopharmaceutical that has the potential to be used as a therapeutic agent. We report here the synthesis and the radiolabeling of {sup 177}Lu-DOTA as well as the biodistribution data of our developed compound.

  6. Effect of radiation and anti-tumor drugs on the immune-lymphoid system

    International Nuclear Information System (INIS)

    An attempt was made to evaluate possible side-effects of radiotherapy and/or chemotherapy of tumors on the immune-lymphoid system. Review of the literature that seems to have significant bearing on this subject included the following: (a) relation of the time of antigenic stimulation to the time of radiation exposure, (b) radiation dose-survival curves of T and B lymphocyte, (c) effects of dose-rate and radiation quality, (d) effects of partial body irradiation, (e) immunosuppressive anti-tumor drugs, and (f) radiation effects on cytotoxic lymphocytes, Available data suggest that the side-effects resulting from radiotherapy of tumors, if any, are not significant provided that the radiation exposure is restricted to the site of tumors. With regard to chemotherapy, the class II drugs (aminopterin etc.) which function as immunosuppressants, especially when given after antigenic stimulation, seem to give fewer side-effects than, the class I (busulfan etc.) or II agents which are active even before immunologic stimulus. Cytotoxic lymphocytes are now known to be highly radioresistant. (auth.)

  7. Effects of sulfanilamide and methotrexate on 13C fluxes through the glycine decarboxylase/serine hydroxymethyltransferase enzyme system in Arabidopsis

    International Nuclear Information System (INIS)

    In C3 plants large amounts of photorespiratory glycine (Gly) are converted to serine by the tetrahydrofolate (THF)-dependent activities of the Gly decarboxylase complex (GDC) and serine hydroxymethyltransferase (SHMT). Using 13C nuclear magnetic resonance, we monitored the flux of carbon through the GDC/SHMT enzyme system in Arabidopsis thaliana (L.) Heynh. Columbia exposed to inhibitors of THF-synthesizing enzymes. Plants exposed for 96 h to sulfanilamide, a dihydropteroate synthase inhibitor, showed little reduction in flux through GDC/SHMT. Two other sulfonamide analogs were tested with similar results, although all three analogs competitively inhibited the partially purified enzyme. However, methotrexate or aminopterin, which are confirmed inhibitors of Arabidopsis dihydrofolate reductase, decreased the flux through the GDC/SHMT system by 60% after 48 h and by 100% in 96 h. The uptake of [alpha-13C]Gly was not inhibited by either drug class. The specificity of methotrexate action was shown by the ability of 5-formyl-THF to restore flux through the GDC/SHMT pathway in methotrexate-inhibited plants. The experiments with sulfonamides strongly suggest that the mitochondrial THF pool has a long half-life. The studies with methotrexate support the additional, critical role of dihydrofolate reductase in recycling THF oxidized in thymidylate synthesis

  8. Active Compounds Against Anopheles minimus Carboxypeptidase B for Malaria Transmission-Blocking Strategy. (United States)

    Mongkol, Watcharakorn; Arunyawat, Uraiwan; Surat, Wunrada; Kubera, Anchanee


    Malaria transmission-blocking compounds have been studied to block the transmission of malaria parasites, especially the drug-resistant Plasmodium. Carboxypeptidase B (CPB) in the midgut of Anopheline mosquitoes has been demonstrated to be essential for the sexual development of Plasmodium in the mosquito. Thus, the CPB is a potential target for blocking compounds. The aim of this research was to screen compounds from the National Cancer Institute (NCI) diversity dataset and U.S. Food and Drug Administration (FDA)-approved drugs that could reduce the Anopheles CPB activity. The cDNA fragment of cpb gene from An. minimus (cpbAmi) was amplified and sequenced. The three-dimensional structure of CPB was predicted from the deduced amino acid sequence. The virtual screening of the compounds from NCI diversity set IV and FDA-approved drugs was performed against CPBAmi. The inhibition activity against CPBAmi of the top-scoring molecules was characterized in vitro. Three compounds-NSC-1014, NSC-332670, and aminopterin with IC50 at 0.99 mM, 1.55 mM, and 0.062 mM, respectively-were found to significantly reduce the CPBAmi activity. PMID:26352934

  9. Differential effects of immunosuppressants and antibiotics on human monoclonal antibody production in SCID mouse ascites by five heterohybridomas. (United States)

    Yoshinari, K; Arai, K


    SCID mice were inoculated with five human-mouse heterohybridomas derived by fusion of human lymph node lymphocytes from lung cancer patients with murine myeloma cells or human-mouse heteromyeloma cells, and the production of their human monoclonal antibodies (MAb) in the mouse ascites was investigated. In a comparison of the effects of pretreatment by i.p. (intraperitoneal) injection of pristane and anti-asialo GM1 serum on the antibody production of three of the hybridomas, pristane pretreatment resulted in substantial antibody production by all three, and pretreatment with anti-asialo GM1 serum resulted in similar or slightly lower levels of antibody production by two of the hybridomas but none by the third. In a second series of experiments using four of the hybridomas with pristane pretreatment, the co-injection of either penicillin G and streptomycin or kanamycin together with the hybridoma at the time of i.p. inoculation resulted in enhanced MAb production by the two heterohybridomas that had been propagated in medium containing hypoxanthine-aminopterin-thymidine (HAT) but not by the two that had been propagated in HAT-free medium. PMID:9523236

  10. Production of immunoglobin G human monoclonal antibodies by cellular fusion method

    International Nuclear Information System (INIS)

    The increasing clinical use of immunological detection i.e. radioimmunoassays (RIA) enzyme linked immunosorment assay (ELISA) and immunoscintigraphy, has focused the attention on the important of monoclonal antibodies production. Monoclonal antibody (MAB) has been prepared by the cellular fusion method using immunoglobin G human (IgGh) as the antigen and polyethylene glycol (PEG) as the fusion agent. Selection of hybridoma cells was carried out using hypoxanthine-aminopterin-thymidine (HAT) medium. The immunoreactivity and specificy of the antibodies were determined by ELISA technique using Goat anti Mouse (GAM) polyclonal antibodies conjugated with horse-radish peroxidase. It has been shown that the MAB secreted from hybridoma cells are specific to IgGh, IgGh-, IgGh-k, IgG1h, and IgG2h. It was also observed that the MAB are specific to goat IgG or rabbit IgG. All MAB in the ascities fluid were IgG1-k class as determined by ouchterlony method. (author). 6 refs.; 4 tabs.; 5 figs

  11. Biochemical transformation of deoxythymidine kinase-deficient mouse cells with uv-irradiated equine herpesvirus type 1

    International Nuclear Information System (INIS)

    A line of 3T3 mouse cells lacking deoxythymidine kinase (dTK-) was stably transformed to the dTK+ phenotype after exposure to uv-irradiated equine herpesvirus type 1 (EHV-1). Biochemical transformants were isolated in a system selective for the dTK+ phenotype (Eagle minimal essential medium containing 10-4 M hypoxanthine, 6 x 10-7 M aminopterin, and 2 x 10-5 M deoxythymidine). Transformation was accompanied by the acquisition of a dTK activity with immunological, electrophoretic, and biochemical characteristics identical to those of the dTK induced by EHV-1 during productive infection. The transformed cells have been maintained in selective culture medium for more than 50 passages and have retained the capacity to express EHV-1-specific antigens. Spontaneous release of infectious virus has not been detected in the transformed lines, and the cells were not oncogenic for athymic nude mice. In contrast to normal dTK+ 3T3 cells, EHV-1 transformants were unable to grow in the presence of arabinosylthymine, a drug selectively phosphorylated by herpesvirus-coded dTK's. These results indicate that a portion of the EHV-1 genome is able to persist in the transformed cells for many generations and be expressed as an enzymatically active viral gene product

  12. Regulatory elements in the introns of the human HPRT gene are necessary for its expression in embryonic stem cells

    International Nuclear Information System (INIS)

    The authors have examined the expression of transfected human hypoxanthine phosphoribosyltransferase minigenes (HPRT) in mouse embryonic stem (ES) cells. cDNA constructs of this gene that have been successfully used in somatic cell lines failed to confer hypoxanthine/aminopterin/thymidine (HAT) resistance in ES cells. In contrast, constructs containing introns 1 and 2 from the HPRT gene produced a high frequency of HAT-resistant colonies. This observation allowed them to identify two sequences in these introns that influence expression of the HPRT gene in ES cells. One element, located in intron 2, is required for effective HPRT expression in thee cells; the other element, located in intron 1, acts as an enhancer of HPRT expression. Using this information, they have constructed an HPRT minigene that can be used for either positive or negative selection in ES cell experiments. This dual capability allows the design of in-out procedures to create subtle changes in target genes by homologous recombination with the aid of this selectable minigene

  13. X-rays induce interallelic homologous recombination at the human thymidine kinase gene

    International Nuclear Information System (INIS)

    The authors have developed a human lymphoblast cell line for the study of interchromosomal homologous recombination at the endogenous thymidine kinase (tk) gene on chromosome 17. This cell line (designated 6:86) carries unique heterozygous frameshift mutations in exons 4 and 7 of its endogenous tk alleles and can revert to TK+ by frame-restoring mutations, gene conversion, or reciprocal recombination. Line 6:86 reverts spontaneously to TK+ at a frequency of 10-7 to 10-8, and exposures to X-irradiation or the frameshift mutagen ICR-191 induce increased reversion frequencies in a dose-dependent manner. Another cell line (designated 4:2) carries a homozygous exon 7 frameshift and is not expected to revert through mechanisms other than frame-restoring mutation. Line 4:2 reverts to TK+ at a lower spontaneous frequency than does 6:86 but can be induced with similar kinetics by ICR-191. In contrast to line 6:86, however, X rays did not induce detectable reversion of line 4:2. We have characterized a number of 6:86-derived revertants by means of restriction fragment length polymorphism analysis at tk and linked loci, single-strand conformation polymorphisms, and direct transcript sequencing. For X rays, most revertants retain both original mutations in the genomic DNA, and a subset of these frameshift-retaining revertants produce frameshift-free message, indicating that reversion is the result of reciprocal recombination within the tk gene. Frame-restoring point mutations, restoration of original sequences, and phenocopy reversion by acquisition of aminopterin resistance were also found among X-ray-induced revertants, whereas the ICR-191-induced revertants examined show only loss of the exon 7 frameshift

  14. Studies of globin gene expression in differentiating erythroid cells

    International Nuclear Information System (INIS)

    The author has addressed questions concerning globin gene expression and the loss of protein synthesis in the terminal stages of erythroid development. (1) The hypothesis that the rate of cell division affects the relative synthesis of γ and β globin in erythroid cells was investigated. The effect of hydroxyurea, aminopterin, or low culture temperature on the in vitro growth of erythroid progenitor cells and on the relative synthesis of γ and β globin was measured. No consistent change in γ globin synthesis was detected. (2) The hypothesis that the ratio of γ and β globin synthesis decreases during erythroid maturation because of differential mRNA stability was investigated. The half-lives of γ and β globin mRNAs and γ and β globin protein synthesis were measured in cultured reticulocytes. γ and β globin mRNAs were assayed by solution hybridization and by in vitro translation. Globin synthesis was determined by 3H-leucine incorporation into the γ and β globin chains. γ and β globin mRNAs decay with similar half-lives in cultured reticulocytes. Therefore, the change in the ratio of γ and β globin synthesis during erythroid maturation cannot be explained by differences in mRNA stability and is likely to result from asynchronous transcription of the genes. These data suggest that protein synthesis in maturing reticulocytes is not limited by the quantity of mRNA but by the availability of translation factors. (3) The hypothesis was tested that the initiation factor GEF becomes limiting for protein synthesis during reticulocyte maturation

  15. Production and characterization of monoclonal antibodies to Brazilian isolates of bovine viral diarrhea virus

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    L.C. Kreutz


    Full Text Available Three Brazilian isolates of bovine viral diarrhea virus (BVDV, antigenically distinct from the standard North American isolates, were selected to immunize BALB/c mice in order to obtain hybridoma cells secreting anti-BVDV monoclonal antibodies (mAbs. Two hybridoma clones secreting mAbs, reacting specifically with BVDV-infected cells (mAbs 3.1C4 and 6.F11, were selected after five fusions and screening of 1001 hypoxanthine-aminopterin-thymidine-resistant clones. These mAbs reacted in an indirect fluorescent antibody (IFA assay with all 39 South and North American BVDV field isolates and reference strains available in our laboratory, yet failed to recognize other pestiviruses, namely the hog cholera virus. The mAbs reacted at dilutions up to 1:25,600 (ascitic fluid and 1:100 (hybridoma culture supernatant in IFA and immunoperoxidase (IPX staining of BVDV-infected cells but only mAb 3.1C4 neutralized virus infectivity. Furthermore, both mAbs failed to recognize BVDV proteins by IPX in formalin-fixed paraffin-embedded tissues and following SDS-PAGE and immunoblot analysis of virus-infected cells, suggesting they are probably directed to conformational-type epitopes. The protein specificity of these mAbs was then determined by IFA staining of CV-1 cells transiently expressing each of the BVDV proteins: mAb 3.1C4 reacted with the structural protein E2/gp53 and mAb 6.F11 reacted with the structural protein E1/gp25. Both mAbs were shown to be of the IgG2a isotype. To our knowledge, these are the first mAbs produced against South American BVDV isolates and will certainly be useful for research and diagnostic purposes.

  16. Establishment and characterization of mouse bone marrow-derived mast cell hybridomas

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    Kawahara, Takeshi, E-mail: [Integrated Department of Sciences of Functional Foods, Graduate School of Agriculture, Shinshu University, Nagano (Japan)


    Interleukin (IL)-3-dependent mouse bone marrow-derived mast cells (BMMCs) are an important model for studying the function of mucosal-type mast cells. In the present study, BMMCs were successfully immortalized by cell fusion using a hypoxanthine-aminopterin-thymidine medium-sensitive variant of P815 mouse mastocytoma (P815-6TgR) as a partner cell line. The established mouse mast cell hybridomas (MMCHs) expressed {alpha}, {beta}, and {gamma} subunits of high-affinity immunoglobulin E (IgE) receptor (Fc{epsilon}RI) and possessed cytoplasmic granules devoid of or partially filled with electron-dense material. Four independent MMCH clones continuously proliferated without supplemental exogenous IL-3 and showed a degranulation response on stimulation with IgE+antigen. Furthermore, histamine synthesis and release by degranulation were confirmed in MMCH-D5, a MMCH clone that showed the strongest degranulation response. MMCH-D5 exhibited elevated levels of IL-3, IL-4, IL-13, granulocyte-macrophage colony-stimulating factor, tumor necrosis factor (TNF)-{alpha}, and cyclooxygenase 2, and production of prostaglandin D{sub 2} and leukotriene C{sub 4} in response to IgE-induced stimulation. MMCH clones also expressed Toll-like receptors (TLRs) 1, 2, 4, and 6 and showed elevated levels of TNF-{alpha} expression in response to stimulation with TLR2 and TLR4 ligands. The MMCHs established using this method should be suitable for studies on Fc{epsilon}RI- and TLR-mediated effector functions of mast cells.

  17. An anti-hapten camelid antibody reveals a cryptic binding site with significant energetic contributions from a nonhypervariable loop

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    Fanning, Sean W.; Horn, James R. (NIU)


    Conventional anti-hapten antibodies typically bind low-molecular weight compounds (haptens) in the crevice between the variable heavy and light chains. Conversely, heavy chain-only camelid antibodies, which lack a light chain, must rely entirely on a single variable domain to recognize haptens. While several anti-hapten VHHs have been generated, little is known regarding the underlying structural and thermodynamic basis for hapten recognition. Here, an anti-methotrexate VHH (anti-MTX VHH) was generated using grafting methods whereby the three complementarity determining regions (CDRs) were inserted onto an existing VHH framework. Thermodynamic analysis of the anti-MTX VHH CDR1-3 Graft revealed a micromolar binding affinity, while the crystal structure of the complex revealed a somewhat surprising noncanonical binding site which involved MTX tunneling under the CDR1 loop. Due to the close proximity of MTX to CDR4, a nonhypervariable loop, the CDR4 loop sequence was subsequently introduced into the CDR1-3 graft, which resulted in a dramatic 1000-fold increase in the binding affinity. Crystal structure analysis of both the free and complex anti-MTX CDR1-4 graft revealed CDR4 plays a significant role in both intermolecular contacts and binding site conformation that appear to contribute toward high affinity binding. Additionally, the anti-MTX VHH possessed relatively high specificity for MTX over closely related compounds aminopterin and folate, demonstrating that VHH domains are capable of binding low-molecular weight ligands with high affinity and specificity, despite their reduced interface.

  18. Detailed analysis of X chromosome inactivation in a 49,XXXXX pentasomy (United States)

    Moraes, Lucia M; Cardoso, Leila CA; Moura, Vera LS; Moreira, Miguel AM; Menezes, Albert N; Llerena, Juan C; Seuánez, Héctor N


    Background Pentasomy X (49,XXXXX) has been associated with a severe clinical condition, presumably resulting from failure or disruption of X chromosome inactivation. Here we report that some human X chromosomes from a patient with 49,XXXXX pentasomy were functionally active following isolation in inter-specific (human-rodent) cell hybrids. A comparison with cytogenetic and molecular findings provided evidence that more than one active X chromosome was likely to be present in the cells of this patient, accounting for her abnormal phenotype. Results 5-bromodeoxyuridine (BrdU)-pulsed cultures showed different patterns among late replicating X chromosomes suggesting that their replication was asynchronic and likely to result in irregular inactivation. Genotyping of the proband and her mother identified four maternal and one paternal X chromosomes in the proband. It also identified the paternal X chromosome haplotype (P), indicating that origin of this X pentasomy resulted from two maternal, meiotic non-disjunctions. Analysis of the HUMANDREC region of the androgen receptor (AR) gene in the patient's mother showed a skewed inactivation pattern, while a similar analysis in the proband showed an active paternal X chromosome and preferentially inactivated X chromosomes carrying the 173 AR allele. Analyses of 33 cell hybrid cell lines selected in medium containing hypoxanthine, aminopterin and thymidine (HAT) allowed for the identification of three maternal X haplotypes (M1, M2 and MR) and showed that X chromosomes with the M1, M2 and P haplotypes were functionally active. In 27 cell hybrids in which more than one X haplotype were detected, analysis of X inactivation patterns provided evidence of preferential inactivation. Conclusion Our findings indicated that 12% of X chromosomes with the M1 haplotype, 43.5% of X chromosomes with the M2 haplotype, and 100% of the paternal X chromosome (with the P haplotype) were likely to be functionally active in the proband's cells, a

  19. Sandwich enzyme-linked immunosorbent assay for naringin. (United States)

    Qu, Huihua; Wang, Xueqian; Qu, Baoping; Kong, Hui; Zhang, Yue; Shan, Wenchao; Cheng, Jinjun; Wang, Qingguo; Zhao, Yan


    Among the currently used immunoassay techniques, sandwich ELISA exhibits higher specificity, lower cross-reactivity, and a wider working range compared to the corresponding competitive assays. However, it is difficult to obtain a pair of antibodies that can simultaneously bind to two epitopes of a molecule with a molecular weight of less than 1000 Da. Naringin (Nar) is a flavonoid with a molecular mass of 580 Da. The main aim of this study was to develop a sandwich ELISA for detecting Nar. Two hybridomas secreting anti-Nar monoclonal antibodies (mAbs) were produced by fusing splenocytes from a mouse immunised against Nar-bovine serum albumin (BSA) conjugated with a hypoxanthine-aminopterin-thymidine (HAT)-sensitive mouse myeloma cell line; a sandwich ELISA for detecting Nar was developed using these two well-characterised anti-Nar mAbs. The performance of the sandwich assay was further evaluated by limit of detection (LOD), limit of quantification (LOQ), recovery, and interference analyses. A dose-response curve to Nar was obtained with an LOD of 6.78 ng mL(-1) and an LOQ of 13.47 ng mL(-1). The inter-assay and intra-assay coefficients of variation were 4.32% and 7.48%, respectively. The recovery rate of Nar from concentrated Fructus aurantii granules was 83.63%. A high correlation was obtained between HPLC and sandwich ELISA. These results demonstrate that the sandwich ELISA method has higher specificity for Nar than indirect competitive ELISA. PMID:26709308

  20. Co-purification of dihydrofolate synthetase and N10formyltetrahydropteroyldiglutamate synthetase from E. coli

    International Nuclear Information System (INIS)

    The enzymatic activities which add a single glutamate to dihydropteroate (H2Pte) and to N10formyltetrahydropteroylglutamate (N10formylH4PteGlu) remained at a constant ratio when various purification techniques were used, including ammonium sulfate fractionation, isoelectric focusing, polyacrylamide gel electrophoresis, and column chromatography on Sephadex G-100, DEAE-Sephadex, CM-Sephadex, ADP-Sepharose, N10formylfolate-agarose or matrix Gel Red-A. The best combination of these methods yielded 900-fold purified enzyme. However, the kinetic properties were dependent upon the substrate used. H2Pte was a noncompetitive inhibitor (Kii . 1.1 microM) of the utilization of N10formylH4PteGlu, but no inhibition was detected in the reciprocal experiment. Aminopterin was a competitive inhibitor (Kis . 370 microM) of the reaction with N10formylH4PteGlu but was not inhibitory with H2Pte as substrate. In the dihydrofolate synthetase reaction, in Tris-HCl, pH 8.9 with 50 mM KCl, the apparent Km values for glutamate and MgATP were 3.5 mM and 8.1 microM respectively. With N10formylH4PteGlu as substrate, these Km values were 1.2 mM and 80 microM. Since the two activities were not separated by protein purification procedures but exhibited different kinetic properties (including lack of reciprocal inhibition), the data suggest these reactions are catalyzed on independent sites of a common protein