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Sample records for split pyrimidine dimers

  1. Biological consequences of cyclobutane pyrimidine dimers

    NARCIS (Netherlands)

    Vink, A.A.; Roza, L.

    2001-01-01

    In the skin many molecules may absorb ultraviolet (UV) radiation upon exposure. In particular, cellular DNA strongly absorbs shorter wavelength solar UV radiation, resulting in various types of DNA damage. Among the DNA photoproducts produced the cyclobutane pyrimidine dimers (CPDs) are predominant.

  2. Analysis of pyrimidine dimer content of isolated DNA by nuclease digestion

    International Nuclear Information System (INIS)

    Farland, W.H.; Sutherland, B.M.

    1980-01-01

    Isolated DNA is highly susceptible to degradation by exogenous nucleases. Complete digestion is possible with a number of well-characterized enzymes from a variety of sources. Treatment of DNA with a battery of enzymes including both phosphodiesterase and phosphatase activities yields a mixture of nucleosides and inorganic phosphate (P/sub i/) as a final product. Unlike native DNA, ultraviolet-irradiated DNA is resistant to complete digestion. Setlow et al. demonstrated that the structural changes in the DNA responsible for the nuclease resistance were the formation of cyclobutyl pyrimidine dimers, the major photoproduct in UV-irradiated DNA. Using venom phosphodiesterase, they demonstrated that UV irradiation of DNA affected both the rate and extent of enzymatic hydrolysis. In addition, it was demonstrated that the major nuclease-resistant product of this hydrolysis was an oligonucleotide containing dimerized pyrimidines. Treatment of the DNA to split the dimers, either photochemically or photoenzymatically, rendered the polymer more susceptible to hydrolysis by the phosphodiesterase. The specificity of photoreactivating enzyme for pyrimidine dimers lends support to the role of these structures in conferring nuclease resistance to UV-irradiated DNA. The nuclease resistance of DNA containing dimers has been the basis of several assays for the measurement of these photoproducts. Sutherland and Chamberlin reported the development of a rapid and sensitive assay for dimers in 32 P-labeled DNA

  3. Excision of UV-induced pyrimidine dimers from DNA of Chinese hamster CHO cells

    Energy Technology Data Exchange (ETDEWEB)

    Barenfel' d, L.S.; Bikhanskaya, F.L. (AN SSSR, Leningrad. Inst. Tsitologii)

    1983-10-01

    The sedimentation method in alkali gradients of saccharose when using UV-endonuclease from Micrococcus lutenius has been applied to investigate cleavage of UV-induced pyrimidine dimers from DNA cells (CHO). It is shown that essential part of pyrimidine dimers (approximately 80%) are cleaved during 26 h of postradiation incubation while during the first 17 h after UV-radiation (4J/m/sup 2/) reparation proceeds negligibly (approximately 15%).

  4. Baculovirus cyclobutane pyrimidine dimer photolyases show a close relationship with lepidopteran host homologues

    NARCIS (Netherlands)

    Biernat, M.A.; Ros, V.I.D.; Vlak, J.M.; Oers, van M.M.

    2011-01-01

    Cyclobutane pyrimidine dimer (CPD) photolyases repair ultraviolet (UV)-induced DNA damage using blue light. To get insight in the origin of baculovirus CPD photolyase (phr) genes, homologues in the lepidopteran insects Chrysodeixis chalcites, Spodoptera exigua and Trichoplusia ni were identified and

  5. Enhanced repair of cyclobutane pyrimidine dimers and improved UV resistance in photolyase transgenic mice

    NARCIS (Netherlands)

    W. Schul; J. Jans (Judith); Y.M. Rijksen (Yvonne); K.H. Klemann; J. de Wit (Jan); O. Nikaido; S. Nakajima; A. Yasui (Akira); J.H.J. Hoeijmakers (Jan); G.T.J. van der Horst (Gijsbertus); A.P.M. Eker (André)

    2002-01-01

    textabstractDuring evolution, placental mammals appear to have lost cyclobutane pyrimidine dimer (CPD) photolyase, an enzyme that efficiently removes UV-induced CPDs from DNA in a light-dependent manner. As a consequence, they have to rely solely on the more complex, and for this lesion less

  6. Removal of uv-induced pyrimidine dimers from the replicated and unreplicated DNA of human fibroblasts

    Energy Technology Data Exchange (ETDEWEB)

    Waters, R.

    1978-01-01

    Excision repair in uv irradiated human fibroblasts has been examined in portions of DNA replicating after irradiation versus those remaining unreplicated. Two approaches, one using a uv-endonuclease to estimate pyrimidine dimers remaining in DNA, the other using density labeling to measure excision resynthesis, indicate that the extent of repair is the same for both replicated and unreplicated DNA.

  7. Quantitation of pyrimidine dimers in DNA from UVB-irradiated alfalfa (Medicago sativa L.) seedlings

    International Nuclear Information System (INIS)

    Quaite, F.E.; Sutherland, B.M.; Sutherland, J.C.

    1991-01-01

    Depletion of stratospheric ozone will increase the solar ultraviolet radiation in the range from 290-320 nm (UVB) that reaches the surface of the earth, placing an increased UV burden on exposed organisms. One consequence of increased UVB may be decreased productivity of crop plants. A principal lesion caused by UV in DNA is the cyclobutyl pyrimidine dimer. We have adapted a method for measuring these dimers in nanogram quantities of non-radioactive DNA for use in UV-irradiated plants. We find that biologically relevant doses of broad band UVB radiation induce easily detectable frequencies of pyrimidine dimers in the DNA of irradiated alfalfa sprout leaves and that the dose response for dimer formation is linear up to doses of at least 690 J/m 2 . We also find easily measurable frequencies of dimers in the leaves of seedlings grown in glass filtered sunlight but not exposed to additional UVB, suggesting that significant number of dimers are formed in plants exposed to normal sunlight. 27 refs., 3 figs., 1 tab

  8. Pyrimidine dimer excision in human cells and skin cancer. [Ultraviolet Radiation

    Energy Technology Data Exchange (ETDEWEB)

    Regan, James D.; Carrier, W. L.; Smith, D. P.; Waters, Raymond

    1977-01-01

    We have compared three different methods for estimating the induction and removal of uv induced pyrimidine dimers from the DNA of human fibroblasts. Results indicate that after uv doses of 5-20 J/m/sup 2/ 50% of the dimers are removed by 24 hours after irradiation. Almost complete excision can be observed if the cells are incubated for periods not less than 72 hours after 5 J/m/sup 2/. After higher doses it probably takes even longer fr such complete removal to be seen.

  9. Cyclobutane pyrimidine dimers photolyase from extremophilic microalga: Remarkable UVB resistance and efficient DNA damage repair

    Energy Technology Data Exchange (ETDEWEB)

    Li, Chongjie [Key Laboratory of Marine Bioactive Substance, The First Institute of Oceanography, State Oceanic Administration, Qingdao 266061 (China); Ma, Li [Key Laboratory of Biofuels, and Shandong Provincial Key Laboratory of Energy Genetics, Qingdao Institute of Bioenergy and Bioprocess Technology, Chinese Academy of Sciences, Qingdao 266101 (China); Mou, Shanli [Yellow Sea Fisheries Research Institute, Chinese Academy of Fishery Sciences, Qingdao (China); Wang, Yibin, E-mail: wangyibin@fio.org.cn [Key Laboratory of Marine Bioactive Substance, The First Institute of Oceanography, State Oceanic Administration, Qingdao 266061 (China); Zheng, Zhou; Liu, Fangming; Qi, Xiaoqing; An, Meiling; Chen, Hao [Key Laboratory of Marine Bioactive Substance, The First Institute of Oceanography, State Oceanic Administration, Qingdao 266061 (China); Miao, Jinlai, E-mail: miaojinlai@163.com [Key Laboratory of Marine Bioactive Substance, The First Institute of Oceanography, State Oceanic Administration, Qingdao 266061 (China); State Key Laboratory of Biological Fermentation Engineering of Beer (In Preparation), Qingdao (China)

    2015-03-15

    Highlights: • Chlamydomonas sp. ICE-L photolyase gene PHR2 is first cloned and expressed in E. coli. • PHR2 complemented E. coli could efficiently survival from UV radiation. • Expressed PHR2 photolyase has distinct photo-reactivation activity in vitro. - Abstract: Bacteria living in the Antarctic region have developed several adaptive features for growth and survival under extreme conditions. Chlamydomonas sp. ICE-Lis well adapted to high levels of solar UV radiation. A putative photolyase was identified in the Chlamydomonas sp. ICE-L transcriptome. The complete cDNA sequence was obtained by RACE-PCR. This PHR encoding includes a polypeptide of 579 amino acids with clear photolyase signatures belonging to class II CPD-photolyases, sharing a high degree of homology with Chlamydomonas reinhardtii (68%). Real-time PCR was performed to investigate the potential DNA damage and responses following UVB exposure. CPD photolyase mRNA expression level increased over 50-fold in response to UVB radiation for 6 h. Using photolyase complementation assay, we demonstrated that DNA photolyase increased photo-repair more than 116-fold in Escherichia coli strain SY2 under 100 μw/cm{sup 2} UVB radiation. To determine whether photolyase is active in vitro, CPD photolyase was over-expressed. It was shown that pyrimidine dimers were split by the action of PHR2. This study reports the unique structure and high activity of the enzyme. These findings are relevant for further understanding of molecular mechanisms of photo-reactivation, and will accelerate the utilization of photolyase in the medical field.

  10. DENV gene of bacteriophage T4 codes for both pyrimidine dimer-DNA glycosylase and apyrimidinic endonuclease activities

    International Nuclear Information System (INIS)

    McMillan, S.; Edenberg, H.J.; Radany, E.H.; Friedberg, R.C.; Friedberg, E.C.

    1981-01-01

    Recent studies have shown that purified preparations of phage T4 UV DNA-incising activity (T4 UV endonuclease or endonuclease V of phase T4) contain a pyrimidine dimer-DNA glycosylase activity that catalyzes hydrolysis of the 5' glycosyl bond of dimerized pyrimidines in UV-irradiated DNA. Such enzyme preparations have also been shown to catalyze the hydrolysis of phosphodiester bonds in UV-irradiated DNA at a neutral pH, presumably reflecting the action of an apurinic/apyrimidinic endonuclease at the apyrimidinic sites created by the pyrimidine dimer-DNA glycosylase. In this study we found that preparations of T4 UV DNA-incising activity contained apurinic/apyrimidinic endonuclease activity that nicked depurinated form I simian virus 40 DNA. Apurinic/apyrimidinic endonuclease activity was also found in extracts of Escherichia coli infected with T4 denV + phage. Extracts of cells infected with T4 denV mutants contained significantly lower levels of apurinic/apyrimidinic endonuclease activity; these levels were no greater than the levels present in extracts of uninfected cells. Furthermore, the addition of DNA containing UV-irradiated DNA and T4 enzyme resulted in competition for pyrimidine dimer-DNA glycosylase activity against the UV-irradiated DNA. On the basis of these results, we concluded that apurinic/apyrimidinic endonuclease activity is encoded by the denV gene of phage T4, the same gene that codes for pyrimidine dimer-DNA glycosylase activity

  11. Excision repair of ultraviolet damage in mammalian cells: evidence for two steps in the excision of pyrimidine dimers

    International Nuclear Information System (INIS)

    Williams, J.I.; Cleaver, J.E.

    1978-01-01

    The incidence of pyrimidine dimer formation and the kinetics of DNA repair in African green monkey kidney CV-1 cells after ultraviolet (uv) irradiation were studied by measuring survival, T4 endonuclease V-sensitive sites, the fraction of pyrimidine dimers in acid-insoluble DNA as determined by thin layer chromatography (TLC), and repair replication. CV-1 cells exhibit a survival curve with extrapolation number n = 7.8 and D 0 = 2.5 J/m 2 . Pyrimidine dimers were lost from acid-insoluble DNA more slowly than endonuclease-sensitive sites were lost from or new bases were incorporated into high molecular weight DNA during the course of repair. Growth of CV-1 cultures in [ 3 H]thymidine or x irradiation (2 or 10 krads) 24 h before uv irradiation had no effect on repair replication induced by 25 J/m 2 of uv. These results suggest that pyrimidine dimer excision measurements by TLC are probably unaffected by radiation from high levels of incorporated radionuclides. The endonuclease-sensitive site and TLC measurements can be reconciled by the assumption that pyrimidine dimers are excised from high molecular weight DNA in acid-insoluble oligonucleotides that are slowly degraded to acid-soluble fragments

  12. One pyrimidine dimer inactivates expression of a transfected gene in xeroderma pigmentosum cells

    International Nuclear Information System (INIS)

    Protic-Sabljic, M.; Kraemer, K.H.

    1985-01-01

    The authors have developed a host cell reactivation assay of DNA repair utilizing UV-treated plasmid vectors. The assay primarily reflects cellular repair of transcriptional activity of damaged DNA measured indirectly as enzyme activity of the transfected genes. They studied three plasmids (pSV2cat, 5020 base pairs; pSV2catSVgpt, 7268 base pairs; and pRSVcat, 5027 base pairs) with different sizes and promoters carrying the bacterial cat gene (CAT, chloramphenicol acetyltransferase) in a construction that permits cat expression in human cells. All human simian virus 40-transformed cells studied expressed high levels of the transfected cat gene. UV treatment of the plasmids prior to transfection resulted in differential decrease in CAT activity in different cell lines. With pSV2catSVgpt, UV inactivation of CAT expression was greater in the xeroderma pigmentosum group A and D lines than in the other human cell lines tested. The D 0 of the CAT inactivation curve was 50 J X m-2 for pSV2cat and for pRSVcat in the xeroderma pigmentosum group A cells. The similarity of the D0 data in the xeroderma pigmentosum group A cells for three plasmids of different size and promoters implies they all have similar UV-inactivation target size. UV-induced pyrimidine dimer formation in the plasmids was quantified by assay of the number of UV-induced T4 endonuclease V-sensitive sites. In the most sensitive xeroderma pigmentosum cells, with all three plasmids, one UV-induced pyrimidine dimer inactivates a target of about 2 kilobases, close to the size of the putative CAT mRNA

  13. Photoprotection by Cichorum endivia extracts: prevention of UVB-induced erythema, pyrimidine dimer formation and IL-6 expression.

    Science.gov (United States)

    Enk, C D; Hochberg, M; Torres, A; Lev, O; Dor, I; Srebnik, M; Dembitsky, V M

    2004-01-01

    In the gradual process of evolution, plants have developed natural sun protecting substances that enable continuous survival under direct and intense ultraviolet (UV) radiation. As part of our studies of plant-derived pigments that might constitute an alternative to conventional sunscreens, we have tested the ethanolic extracts of roots, stalks, and inflorescences of populations of wild Cichorum endivia subsp. Divaricatum (Asteraceae) in terms of protection against sunburn, and in prevention of UVB-induced pyrimidine dimer formation and IL-6 mRNA expression in the human keratinocyte cell line, HaCaT. Using ELISA technique for detection of pyrimidine dimers and RT-PCR for detection of IL-6, we found that the ethanolic extract of C. endivia roots absorbs radiation in the UVB spectrum and partially prevents induction of pyrimidine dimers and IL-6 expression. Application of the root extract on the skin prior to UVB irradiation totally prevented erythema. Our findings suggest that C. endivia extracts might possess sun-protective qualities that make them useful as sunscreens. Copyright 2004 S. Karger AG, Basel

  14. Photoreactivation of pyrimidine dimers generated by a photosensitized reaction in RNA of the Smittia sp. embryos after UV-irradiation

    Energy Technology Data Exchange (ETDEWEB)

    Kal' thoff, K.; Iekle, G. (Texas Univ., Austin (USA). Dept. of Zoology)

    1981-12-01

    Mechanisms of biological effects resulting from the irradiation of Smittia sp. embryos in an early stage of development with UV rays with the wave-length of 265, 285 and 295 nm are investigated. It is shown that the cessation of development, deceleration of protein synthesis and emergence of additional abdomens after the irradiation of embryos in early stages of development are not connected with the damage of the nucleus but with the formation of pyrimidine dimers in RNA in the cortical layer of ovum cytoplasm. At first, the energy of UV rays with the given wave-lengths is accepted in the cell by molecules-photosensitizers. It is shown for the first time that pyrimidine dimers generated in RNA can be photoreactivated on exposure of cells to light. Maternal RNA accumulated during oogenesis play an important role in the early embryogeny of insects and other animals ova developing in the sunlight. Therefore, the protection of embryo RNA from solar UV irradiation damage is provided for by the mechanisms of RNA pyrimidine dimers photoreactivation resulted from the sunlight long waves.

  15. UV-B-inducible and temperature-sensitive photoreactivation of cyclobutane pyrimidine dimers in Arabidopsis thaliana

    International Nuclear Information System (INIS)

    Pang, Qishen; Hays, J.B.

    1991-01-01

    Removal of cyclobutane pyrimidine dimers (CBPDs) in vivo from the DNA of UV-irradiated eight-leaf seedlings of Arabidopsis thaliana was rapid in the presence of visible light (half-life about 1 hour); removal of CBPDs in the dark, presumably via excision repair, was an order of magnitude slower. Extracts of plants contained significant photolyase in vitro, as assayed by restoration of transforming activity to UV-irradiated Escherichia coli plasmids; activity was maximal from four-leaf to 12-leaf stages. UV-B treatment of seedlings for 6 hours increased photolyase specific activity in extracts twofold. Arabidopsis photolyase was markedly temperature-sensitive, both in vitro (half-life at 30C about 12 minutes) and in vivo (half-life at 30C, 30 to 45 minutes). The wavelength dependency of the photoreactivation cross-section showed a broad peak at 375 to 400 nm, and is thus similar to that for maize pollen; it overlaps bacterial and yeast photolyase action spectra

  16. Influence of cytosine methylation on ultraviolet-induced cyclobutane pyrimidine dimer formation in genomic DNA

    Energy Technology Data Exchange (ETDEWEB)

    Rochette, Patrick J. [Division of Pathology, Department of Medical Biology, Universite Laval, Quebec, QC (Canada); Division of Genetics, Department of Pediatrics, Faculty of Medicine and Health Sciences, Universite de Sherbrooke, Sherbrooke, QC (Canada); Department of Therapeutic Radiology, Yale School of Medicine, New Haven, CT (United States); Lacoste, Sandrine [Division of Pathology, Department of Medical Biology, Universite Laval, Quebec, QC (Canada); Division of Genetics, Department of Pediatrics, Faculty of Medicine and Health Sciences, Universite de Sherbrooke, Sherbrooke, QC (Canada); Manitoba Institute of Cell Biology, University of Manitoba, Winnipeg, MB (Canada); Therrien, Jean-Philippe [Division of Pathology, Department of Medical Biology, Universite Laval, Quebec, QC (Canada); Bastien, Nathalie [Division of Pathology, Department of Medical Biology, Universite Laval, Quebec, QC (Canada); Division of Genetics, Department of Pediatrics, Faculty of Medicine and Health Sciences, Universite de Sherbrooke, Sherbrooke, QC (Canada); Brash, Douglas E. [Department of Therapeutic Radiology, Yale School of Medicine, New Haven, CT (United States); Drouin, Regen, E-mail: Regen.Drouin@USherbrooke.ca [Division of Pathology, Department of Medical Biology, Universite Laval, Quebec, QC (Canada); Division of Genetics, Department of Pediatrics, Faculty of Medicine and Health Sciences, Universite de Sherbrooke, Sherbrooke, QC (Canada)

    2009-06-01

    The ultraviolet (UV) component of sunlight is the main cause of skin cancer. More than 50% of all non-melanoma skin cancers and >90% of squamous cell carcinomas in the US carry a sunlight-induced mutation in the p53 tumor suppressor gene. These mutations have a strong tendency to occur at methylated cytosines. Ligation-mediated PCR (LMPCR) was used to compare at nucleotide resolution DNA photoproduct formation at dipyrimidine sites either containing or lacking a methylated cytosine. For this purpose, we exploited the fact that the X chromosome is methylated in females only on the inactive X chromosome, and that the FMR1 (fragile-X mental retardation 1) gene is methylated only in fragile-X syndrome male patients. Purified genomic DNA was irradiated with UVC (254 nm), UVB (290-320 nm) or monochromatic UVB (302 and 313 nm) to determine the effect of different wavelengths on cyclobutane pyrimidine dimer (CPD) formation along the X-linked PGK1 (phosphoglycerate kinase 1) and FMR1 genes. We show that constitutive methylation of cytosine increases the frequency of UVB-induced CPD formation by 1.7-fold, confirming that methylation per se is influencing the probability of damage formation. This was true for both UVB sources used, either broadband or monochromatic, but not for UVC. Our data prove unequivocally that following UVB exposure methylated cytosines are significantly more susceptible to CPD formation compared with unmethylated cytosines.

  17. Influence of cytosine methylation on ultraviolet-induced cyclobutane pyrimidine dimer formation in genomic DNA

    International Nuclear Information System (INIS)

    Rochette, Patrick J.; Lacoste, Sandrine; Therrien, Jean-Philippe; Bastien, Nathalie; Brash, Douglas E.; Drouin, Regen

    2009-01-01

    The ultraviolet (UV) component of sunlight is the main cause of skin cancer. More than 50% of all non-melanoma skin cancers and >90% of squamous cell carcinomas in the US carry a sunlight-induced mutation in the p53 tumor suppressor gene. These mutations have a strong tendency to occur at methylated cytosines. Ligation-mediated PCR (LMPCR) was used to compare at nucleotide resolution DNA photoproduct formation at dipyrimidine sites either containing or lacking a methylated cytosine. For this purpose, we exploited the fact that the X chromosome is methylated in females only on the inactive X chromosome, and that the FMR1 (fragile-X mental retardation 1) gene is methylated only in fragile-X syndrome male patients. Purified genomic DNA was irradiated with UVC (254 nm), UVB (290-320 nm) or monochromatic UVB (302 and 313 nm) to determine the effect of different wavelengths on cyclobutane pyrimidine dimer (CPD) formation along the X-linked PGK1 (phosphoglycerate kinase 1) and FMR1 genes. We show that constitutive methylation of cytosine increases the frequency of UVB-induced CPD formation by 1.7-fold, confirming that methylation per se is influencing the probability of damage formation. This was true for both UVB sources used, either broadband or monochromatic, but not for UVC. Our data prove unequivocally that following UVB exposure methylated cytosines are significantly more susceptible to CPD formation compared with unmethylated cytosines.

  18. Excision of pyrimidine dimers from epidermal DNA and nonsemiconservative epidermal DNA synthesis following ultraviolet irradiation of mouse skin

    Energy Technology Data Exchange (ETDEWEB)

    Bowden, G.T.; Trosko, J.E.; Shapas, B.G.; Boutwell, R.K.

    1975-12-01

    Pyrimidine dimer production and excision in epidermal DNA were studied at five different dose levels of ultraviolet light in the skin of intact mice. Dimer production increased with dose up to 50,400 ergs/sq mm. Approximately 30 percent of the thymine-containing dimers were excised by 24 hr after irradiation at three lower dose levels of ultraviolet light. Nonsemiconservative DNA replication in ultraviolet-irradiated mouse skin was shown to continue for at least 18 hr. The rate of nonsemiconservative replication decreased with time, but did so slowly. The initial rates of nonsemiconservative replication increased with ultraviolet light dose levels up to about 4200 ergs/sq mm, after which the initial rates were decreased. Semiconservative epidermal DNA synthesis was shown to be inhibited by hydroxyurea, but hydroxyurea had no effect on ultraviolet light-induced nonsemiconservative DNA replication. The observed pyrimidine dimer excision and nonsemiconservative DNA replication suggest that in the intact mouse the cells of the epidermis are capable of DNA excision repair after ultraviolet irradiation of mouse skin.

  19. Comparative studies on the correlation between pyrimidine dimer formation and tyrosinase activity in Cloudman S91 melanoma cells after ultraviolet-irradiation

    International Nuclear Information System (INIS)

    Niggli, H.J.

    1990-01-01

    The authors compared the induction of pyrimidine dimer densities after UV-irradiation in mouse melanoma cells before and after treatment with cholera toxin. Treatment with cholera toxin stimulated tyrosinase activity up to 50-fold, leading to a marked, visually apparent increase in cellular melanin concentrations. Results indicate that de novo melanin pigmentation induced via the c-AMP pathway is not involved in protection against UV-induced thymine-containing pyrimidine dimers. In separate experiments, irradiation of toxin-treated and untreated mouse melanoma cells with UVC or UVB light produced a 20-30% lower dimer density compared to irradiated human skin fibroblasts. This finding suggests that melanin has some protection properties against UV-induced pyrimidine dimers, although the exact defense mechanism seems highly complex. (author)

  20. Ultraviolet-B-induced cyclobutane-pyrimidine dimer formation and repair in Arctic marine macrophytes.

    Science.gov (United States)

    van de Poll, Willem H; Hanelt, Dieter; Hoyer, Kirsten; Buma, Anita G J; Breeman, Anneke M

    2002-11-01

    The significance of ultraviolet-B radiation (UVBR: 280-315 nm)-induced DNA damage as a stress factor for Arctic marine macrophytes was examined in the Kongsfjord (Spitsbergen, 78 degrees 55.5'N, 11 degrees 56.0'E) in summer. UVBR penetration in the water column was monitored as accumulation of cyclobutane-pyrimidine dimers (CPD) in bare DNA. This showed that UVBR transparency of the fjord was variable, with 1% depths ranging between 4 and 8 m. In addition, induction and repair kinetics of CPD were studied in several subtidal macrophytes obtained from the Kongsfjord (5-15 m). Surface exposure experiments demonstrated CPD accumulation in Palmaria palmata, Devaleraea ramentacea, Phycodrys rubens, Coccotylus truncatus and Odonthalia dentata. In artificial light, field collected material of P. palmata, D. ramentacea, P. rubens and Laminaria saccharina showed efficient CPD repair, with only 10% of the artificially induced CPD remaining after 5 h. No significant differences in repair rate were observed among these species. CPD repair was slower or absent in O. dentata, C. truncatus and Monostroma arcticum, indicating that fast repair mechanisms such as photolyase were not continuously expressed in these species. CPD repair rates were not directly related to the vertical distribution of algae in the water column and to the reported UV sensitivity of the examined species. Dosimeter incubations showed that maximal exposure to DNA damaging wavelengths was low for all examined species. Furthermore, most species collected below the 1% depth for DNA damage displayed efficient CPD repair, suggesting that UVBR-induced CPD currently impose a minor threat for mature stages of these species growing in the Kongsfjord, Spitsbergen.

  1. Genetic and phylogenetic characterization of the type II cyclobutane pyrimidine dimer photolyases encoded by Leporipoxviruses

    International Nuclear Information System (INIS)

    Bennett, C. James; Webb, Melissa; Willer, David O.; Evans, David H.

    2003-01-01

    Shope fibroma virus and myxoma virus encode proteins predicted to be Type II photolyases. These are enzymes that catalyze light-dependent repair of cyclobutane pyrimidine dimers (CPDs). When the Shope fibroma virus S127L gene was expressed in an Escherichia coli strain lacking functional CPD repair pathways, the expressed gene protected the bacteria from 70-75% of the ultraviolet (UV) light-induced cytotoxic DNA damage. This proportion suggests that Leporipoxvirus photolyases can only repair CPDs, which typically comprise ∼70% of the damage caused by short wavelength UV light. To test whether these enzymes can protect virus genomes from UV, we exposed virus suspensions to UV-C light followed by graded exposure to filtered visible light. Viruses encoding a deletion of the putative photolyase gene were unable to photoreactivate UV damage while this treatment again eliminated 70-90% of the lethal photoproducts in wild-type viruses. Western blotting detected photolyase protein in extracts prepared from purified virions and it can be deduced that the poxvirion interior must be fluid enough to permit diffusion of this ∼50-kDa DNA-binding protein to the sites where it catalyzes photoreactivation. Photolyase promoters are difficult to categorize using bioinformatics methods, as they do not obviously resemble any of the known poxvirus promoter motifs. By fusing the SFV promoter to DNA encoding a luciferase open reading frame, the photolyase promoter was found to exhibit very weak late promoter activity. These data show that the genomes of Leporipoxviruses, similar to that of fowlpox virus, encode catalytically active photolyases. Phylogenetic studies also confirmed the monophyletic origin of poxviruses and suggest an ancient origin for these genes and perhaps poxviruses

  2. Xeroderma pigmentosum complementation group C cells remove pyrimidine dimers selectively from the transcribed strand of active genes

    International Nuclear Information System (INIS)

    Venema, J.; van Hoffen, A.; Karcagi, V.; Natarajan, A.T.; van Zeeland, A.A.; Mullenders, L.H.

    1991-01-01

    The authors have measured the removal of UV-induced pyrimidine dimers from DNA fragments of the adenosine deaminase (ADA) and dihydrofolate reductase (DHFR) genes in primary normal human and xeroderma pigmentosum complementation group C (XP-C) cells. Using strand-specific probes, we show that in normal cells, preferential repair of the 5' part of the ADA gene is due to the rapid and efficient repair of the transcribed strand. Within 8 h after irradiation with UV at 10 J m-2, 70% of the pyrimidine dimers in this strand are removed. The nontranscribed strand is repaired at a much slower rate, with 30% dimers removed after 8 h. Repair of the transcribed strand in XP-C cells occurs at a rate indistinguishable from that in normal cells, but the nontranscribed strand is not repaired significantly in these cells. Similar results were obtained for the DHFR gene. In the 3' part of the ADA gene, however, both normal and XP-C cells perform fast and efficient repair of either strand, which is likely to be caused by the presence of transcription units on both strands. The factor defective in XP-C cells is apparently involved in the processing of DNA damage in inactive parts of the genome, including nontranscribed strands of active genes. These findings have important implications for the understanding of the mechanism of UV-induced excision repair and mutagenesis in mammalian cells

  3. Replication of UV-irradiated DNA in human cell extracts: Evidence for mutagenic bypass of pyrimidine dimers

    Energy Technology Data Exchange (ETDEWEB)

    Thomas, D.C.; Kunkel, T.A. (National Institute of Environmental Health Sciences, Research Triangle Park, NC (United States))

    1993-08-15

    The authors have examined the efficiency and fidelity of simian virus 40-origin-dependent replication of UV-irradiated double-stranded DNA in extracts of human cells. Using as a mutational target the [alpha]-complementation domain of the Escherichia coli lacZ gene in bacteriophage M13mp2DNA, replication of undamaged DNA in HeLa cell extracts was highly accurate, whereas replication of DNA irradiated with UV light (280-320 nm) was both less efficient and less accurate. Replication was inhibited by irradiation in a dose-dependent manner. Nonetheless, covalently closed, monomer-length circular products were generated that were resistant to digestion by Dpn I, showing that they resulted from semiconservative replication. These products were incised by T4 endonuclease V, whereas the undamaged replication products were not, suggesting that pyrimidine dimers were bypassed during replication. When replicated, UV-irradiated DNA was used to transfect an E. coli [alpha]-complementation host strain to score mutant M13mp2 plaques, the mutant plaque frequency was substantially higher than that obtained with either unirradiated, replicated DNA, or unreplicated, UV-irradiated DNA. Both the increased mutagenicity and the inhibition of replication associated with UV irradiation were reversed by treatment of the irradiated DNA with photolyase before replication. Sequence analysis of mutants resulting from replication of UV-irradiated DNA demonstrated that most mutants contained C [yields] T transition errors at dipyrimidine sites. A few mutants contained 1-nt frameshift errors or tandem double CC [yields] TT substitutions. The data are consistent with the interpretation that pyrimidine dimers are bypassed during replication by the multiprotein replication apparatus in human cell extracts and that this bypass is mutagenic primarily via misincorporation of dAMP opposite a cytosine (or uracil) in the dimer. 56 refs., 2 figs., 3 tabs.

  4. Apoptosis induced by pyrimidine dimer produced by ultraviolet irradiation in cultured cyprinodont cells. Analysis utilizing the evasion from photolysis

    International Nuclear Information System (INIS)

    Nishigaki, Reiko

    2000-01-01

    This is the review of author's investigations on the mechanism of apoptosis induced by UV irradiation in cultured cyprinodont cells highly expressing photolyases of cyclobutane pyrimidine dimer (CPD). Authors found out the evasion from photolysis by UV-induced apoptosis of which cascade had been thought irreversible: the cascade was reversible until the process of DNA fragmentation. In controlling the process, a mechanism to recognize CPD was found concerned. In those cells, morphological changes by UVC were reversible ones in apoptosis from which they evaded if CPD was repaired. Investigations on caspase, which playing important roles in apoptosis, revealed that the DEVD-cleaving enzyme activities were regulated by CPD quantity. However, differing from mammalian cells, elevation of caspase (-7, -3A and -3B) activities did not always induce the morphologic changes and DNA fragmentation. Further studies were thought necessary to elucidate the mechanism of apoptosis in those fish cells. (K.H.)

  5. Role of antioxidants in prevention of pyrimidine dimer formation in UVB irradiated human HaCaT keratinocytes.

    Science.gov (United States)

    Hochberg, Malka; Kohen, Ron; Enk, Claes D

    2006-06-01

    The objective of the present study was to study the role of reactive oxygen species (ROS) in UVB induced cyclobutane pyrimidine dimer (CPD) formation in human keratinocytes, and to examine the modulating activity of low molecular weight antioxidants. To demonstrate the involvement of ROS, we examined the protective capacity of alpha-tocopherol, tempamine, and diethyldithiocarbamate (DDC) on CPD formation in intact cells and naked DNA. HaCaT cells and naked DNA in water solution were irradiated with UVB in the presence of the antioxidants and CPD was determined by ELISA. We found that all three antioxidants provided protection against UVB induced CPD formation. The protection was observed in intact cells only and not in naked DNA. Since some of the tested antioxidants do not possess UV absorbing qualities, our findings suggest that in a cellular environment ROS play a role in CPD formation.

  6. Inhibition of semiconservative DNA synthesis in ICR 2A frog cells by pyrimidine dimers and nondimer photoproducts induced by ultraviolet radiation

    International Nuclear Information System (INIS)

    Rosenstein, B.S.

    1984-01-01

    DNA synthesis was examined in ultraviolet (uv)-irradiated ICR 2A frog cells in which either pyrimidine dimers or nondimer photoproducts represented the major class of DNA lesions. In addition, cells were exposed to 60 Co γ rays. The cultures were pulse-labeled and the size distribution of the DNA synthesized was estimated using both sucrose gradient sedimentation and alkaline step elution. Using either of these techniques, it was found that the presence of dimers resulted in a reduction principally in the synthesis of high molecular weight (MW) DNA. In contrast, nondimer photoproducts caused a strong inhibition in the synthesis of low MW DNA, as was also observed in γ-irradiated cells. Hence the induction of pyrimidine dimers in DNA mainly affected the elongation of replicons, whereas nondimer lesions primarily caused an inhibition of replicon initiation

  7. Inhibition of semiconservative DNA synthesis in ICR 2A frog cells by pyrimidine dimers and nondimer photoproducts induced by ultraviolet radiation

    Energy Technology Data Exchange (ETDEWEB)

    Rosenstein, B.S.

    1984-11-01

    DNA synthesis was examined in ultraviolet (uv)-irradiated ICR 2A frog cells in which either pyrimidine dimers or nondimer photoproducts represented the major class of DNA lesions. In addition, cells were exposed to /sup 60/Co ..gamma.. rays. The cultures were pulse-labeled and the size distribution of the DNA synthesized was estimated using both sucrose gradient sedimentation and alkaline step elution. Using either of these techniques, it was found that the presence of dimers resulted in a reduction principally in the synthesis of high molecular weight (MW) DNA. In contrast, nondimer photoproducts caused a strong inhibition in the synthesis of low MW DNA, as was also observed in ..gamma..-irradiated cells. Hence the induction of pyrimidine dimers in DNA mainly affected the elongation of replicons, whereas nondimer lesions primarily caused an inhibition of replicon initiation.

  8. Gap solitons in a chain of split-ring resonator dimers

    Energy Technology Data Exchange (ETDEWEB)

    Cui, Wei-na, E-mail: cuiweinaa@163.com [Department of Applied Physics, Nanjing University of Science and Technology, Nanjing 210094 (China); Li, Hong-xia, E-mail: hxli@njust.edu.cn [Department of Applied Physics, Nanjing University of Science and Technology, Nanjing 210094 (China); Sun, Min [Department of Applied Physics, Nanjing University of Science and Technology, Nanjing 210094 (China); Bu, Ling-bing [Collaborative Innovation Center on Forecast and Evaluation of Meteorological Disasters, Key Laboratory for Aerosol-Cloud-Precipitation of China Meteorological Administration, Key Laboratory of Meteorological Disaster of Ministry of Education, Nanjing University of Information Science and Technology, Nanjing 210044 (China)

    2017-06-21

    Dynamics of a chain of split-ring resonator dimers with Kerr nonlinear interaction are investigated. A dimer is built as a pair of coupled split-ring resonators with different size. It is shown that the gap solitons with frequency lying in the gap exist due to the interaction of the discreteness and nonlinearity. Such localized structures are studied in the phase plane and analytical and numerical expressions are also obtained. - Highlights: • The coupling of the two modes is studied in the chain of split-ring resonator dimers with Kerr nonlinear interaction. • The evolution of the localized structures is studied in the phase plane. • This system supports gap solitons with the frequencies lying in the gap.

  9. Study of dimerization reaction during cathodic splitting of halogen. Dimerization during reduction of butyl iodide

    International Nuclear Information System (INIS)

    Tomilov, A.P.

    2001-01-01

    The process of electrochemical reduction of butyl iodide in methanol in the presence of sodium methylate was studied. It was ascertained that the yield of dimer product, i. e. octane, depends essentially on the cathode material. Copper and iron (steel 3) proved the most active agents in dimerization process. Conditions (current density 0.03-0.10 A/cm 2 , 0 deg C, 0.005 M CH 3 ONa), under which octane yield amounts to 83-84% in matter, were found [ru

  10. Identification of a large genomic region in UV-irradiated human cells which has fewer cyclobutane pyrimidine dimers than most genomic regions

    Energy Technology Data Exchange (ETDEWEB)

    Kantor, G.J.; Deiss-Tolbert, D.M. [Wright State Univ., Dayton, OH (United States)

    1995-08-01

    Size separation after UV-endonuclease digestion of DNA from UV-irradiated human cells using denaturing conditions fractionates the genome based on cyclobutane pyrimidine dimer content. We have examined the largest molecules available (50-80 kb; about 5% of the DNA) after fractionation and those of average size (5-15 kb) for content of some specific genes. We find that the largest molecules are not a representative sampling of the genome. Three contiguous genes located in a G+C-rich isochore (tyrosine hydroxylase, insulin, insulin-like growth factor II) have concentrations two to three times greater in the largest molecules. This shows that this genomic region has fewer pyrimidine dimers than most other genomic regions. In contrast, the {beta}-actin genomic region, which has a similar G+C content, has an equal concentration in both fractions as do the p53 and {beta}-globin genomic regions, which are A+T-rich. These data show that DNA damage in the form of cyclobutane pyrimidine dimers occurs with different probabilities in specific isochores. Part of the reason may be the relative G-C content, but other factors must play a significant role. We also report that the transcriptionally inactive insulin region is repaired at the genome-overall rate in normal cells and is not repaired in xeroderma pigmentosum complementation group C cells. (author).

  11. Selective inhibition by methoxyamine of the apurinic/apyrimidinic endonuclease activity associated with pyrimidine dimer-DNA glycosylases from Micrococcus luteus and bacteriophage T4

    International Nuclear Information System (INIS)

    Liuzzi, M.; Weinfeld, M.; Paterson, M.C.

    1987-01-01

    The UV endonucleases from Micrococcus luteus and bacteriophage T4 possess two catalytic activities specific for the site of cyclobutane pyrimidine dimers in UV-irradiated DNA: a DNA glycosylase that cleaves the 5'-glycosyl bond of the dimerized pyrimidines and an apurinic/apyrimidinic (AP) endonuclease that thereupon incises the phosphodiester bond 3' to the resulting apyrimidinic site. The authors have explored the potential use of methoxyamine, a chemical that reacts at neutral pH with AP sites in DNA, as a selective inhibitor of the AP endonuclease activities residing in the M. luteus and T4 enzymes. The presence of 50 mM methoxyamine during incubation of UV-treated, [ 3 H]thymine-labeled poly(dA) x poly(dT) with either enzyme preparation was found to protect completely the irradiated copolymer from endonucleolytic attack at dimer sites, as assayed by yield of acid-soluble radioactivity. In contrast, the dimer-DNA glycosylase activity of each enzyme remained fully functional, as monitored retrospectively by release of free thymine after either photochemical-(5 kJ/m 2 , 254 nm) or photoenzymic- (Escherichia coli photolyase plus visible light) induced reversal of pyrimidine dimers in the UV-damaged substrate. The data demonstrate that the inhibition of the strand-incision reaction arises because of chemical modification of the AP sites and is not due to inactivation of the enzyme by methoxyamine. The results, combined with earlier findings for 5'-acting AP endonucleases, strongly suggest that methoxyamine is a highly specific inhibitor of virtually all AP endonucleases, irrespective of their modes of action, and may therefore prove useful in a wide variety of DNA repair studies

  12. As(III) inhibits ultraviolet radiation-induced cyclobutane pyrimidine dimers repair via generation of nitric oxide in human keratinocytes

    Science.gov (United States)

    Ding, Wei; Hudson, Laurie G.; Sun, Xi; Feng, Changjian; Liu, Ke Jian

    2008-01-01

    Inorganic arsenic enhances skin tumor formation when combined with other carcinogens including ultraviolet radiation (UVR). The inhibition of DNA damage repair by arsenic has been hypothesized to contribute to the co-carcinogenic activities of arsenic observed in vivo. Cyclobutane pyrimidine dimers (CPDs) are an important mutagenic UVR photoproduct and implicated in the genesis of non-melanoma skin cancer. The current study demonstrates that low concentrations of arsenite (As(III)) inhibit UVR-induced CPDs repair in a human keratinocyte cell line via nitric oxide (NO) and inducible nitric oxide synthase (iNOS). Following As(III) treatment, NO production and iNOS expression are elevated. Little is known about regulation of iNOS by As(III) and further investigations indicated that p38 mitogen-activated protein kinase (p38 MAPK) and NF-κB are required for As(III) induction of iNOS expression. This As(III)-stimulated signaling cascade was involved in inhibition of UVR-induced CPDs repair as disruption of p38 MAPK activity and NF-κB nuclear translocation counteracted the effects of As(III) on CPD repair. Selective inhibition of iNOS ameliorated As(III) inhibition of CPDs repair thereby suggesting that iNOS is a downstream mediator of As(III) activity. These findings provide evidence that an As(III) stimulated signal transduction cascade culminating in elevated iNOS expression and NO generation is an underlying mechanism for inhibition of UVR-induced DNA damage repair by arsenic. PMID:18621123

  13. Quantitative characterization of pyrimidine dimer excision from UV-irradiated DNA (excision capacity) by cell-free extracts of the yeast Saccharomyces cerevisiae

    International Nuclear Information System (INIS)

    Bekker, M.L.; Kaboev, O.K.; Akhmedov, A.T.; Luchkina, L.A.

    1984-01-01

    Cell-free extracts from wild-type yeast (RAD + ) and from rad mutants belonging to the RAD3 epistatic group (rad1-1, rad2-1, rad3-1, rad4-1) contain activities catalyzing the excision of pyrimidine dimers (PD) from purified ultraviolet-irradiated DNA which was not pre-treated with exogenous UV-endonuclease. The level of these activities in cell-free extracts from rad mutants did not differ from that in wild-type extract and was close to the in vivo excision capacity of the latter calculated from the LD 37 (about 10 4 PD per haploid genome). (Auth.)

  14. The Roles of Several Residues of Escherichia coli DNA Photolyase in the Highly Efficient Photo-Repair of Cyclobutane Pyrimidine Dimers

    Directory of Open Access Journals (Sweden)

    Lei Xu

    2010-01-01

    Full Text Available Escherichia coli DNA photolyase is an enzyme that repairs the major kind of UV-induced lesions, cyclobutane pyrimidine dimer (CPD in DNA utilizing 350–450 nm light as energy source. The enzyme has very high photo-repair efficiency (the quantum yield of the reaction is ~0.85, which is significantly greater than many model compounds that mimic photolyase. This suggests that some residues of the protein play important roles in the photo-repair of CPD. In this paper, we have focused on several residues discussed their roles in catalysis by reviewing the existing literature and some hypotheses.

  15. Exciton Splitting of Adsorbed and Free 4-Nitroazobenzene Dimers: A Quantum Chemical Study.

    Science.gov (United States)

    Titov, Evgenii; Saalfrank, Peter

    2016-05-19

    Molecular photoswitches such as azobenzenes, which undergo photochemical trans ↔ cis isomerizations, are often mounted for possible applications on a surface and/or surrounded by other switches, for example, in self-assembled monolayers. This may suppress the isomerization cross section due to possible steric reasons, or, as recently speculated, by exciton coupling to neighboring switches, leading to ultrafast electronic quenching (Gahl et al., J. Am. Chem. Soc. 2010, 132, 1831). The presence of exciton coupling has been anticipated from a blue shift of the optical absorption band, compared to molecules in solution. From the theory side the need arises to properly analyze and quantify the change of absorption spectra of interacting and adsorbed switches. In particular, suitable methods should be identified, and effects of intermolecule and molecule-surface interactions on spectra should be disentangled. In this paper by means of time-dependent Hartree-Fock (TD-HF), various flavors of time-dependent density functional theory (TD-DFT), and the correlated wave function based coupled-cluster (CC2) method we investigated the 4-nitroazobenzene molecule as an example: The low-lying singlet excited states in the isolated trans monomer and dimer as well as their composites with a silicon pentamantane nanocluster, which serves also as a crude model for a silicon surface, were determined. As most important results we found that (i) HF, CC2, range-separated density functionals, or global hybrids with large amount of exact exchange are able to describe exciton (Davydov) splitting properly, while hybrids with small amount of exact exchange fail producing spurious charge transfer. (ii) The exciton splitting in a free dimer would lead to a blue shift of the absorption signal; however, this effect is almost nullified or even overcompensated by the shift arising from van der Waals interactions between the two molecules. (iii) Adsorption on the Si "surface" leads to a further

  16. Fully functional global genome repair of (6-4) photoproducts and compromised transcription-coupled repair of cyclobutane pyrimidine dimers in condensed mitotic chromatin

    International Nuclear Information System (INIS)

    Komura, Jun-ichiro; Ikehata, Hironobu; Mori, Toshio; Ono, Tetsuya

    2012-01-01

    During mitosis, chromatin is highly condensed, and activities such as transcription and semiconservative replication do not occur. Consequently, the condensed condition of mitotic chromatin is assumed to inhibit DNA metabolism by impeding the access of DNA-transacting proteins. However, about 40 years ago, several researchers observed unscheduled DNA synthesis in UV-irradiated mitotic chromosomes, suggesting the presence of excision repair. We re-examined this subject by directly measuring the removal of UV-induced DNA lesions by an ELISA and by a Southern-based technique in HeLa cells arrested at mitosis. We observed that the removal of (6-4) photoproducts from the overall genome in mitotic cells was as efficient as in interphase cells. This suggests that global genome repair of (6-4) photoproducts is fully functional during mitosis, and that the DNA in mitotic chromatin is accessible to proteins involved in this mode of DNA repair. Nevertheless, not all modes of DNA repair seem fully functional during mitosis. We also observed that the removal of cyclobutane pyrimidine dimers from the dihydrofolate reductase and c-MYC genes in mitotic cells was very slow. This suggests that transcription-coupled repair of cyclobutane pyrimidine dimers is compromised or non-functional during mitosis, which is probably the consequence of mitotic transcriptional repression. -- Highlights: ► Global genome repair of (6-4) photoproducts is fully active in mitotic cells. ► DNA in condensed mitotic chromatin does not seem inaccessible or inert. ► Mitotic transcriptional repression may impair transcription-coupled repair.

  17. Fully functional global genome repair of (6-4) photoproducts and compromised transcription-coupled repair of cyclobutane pyrimidine dimers in condensed mitotic chromatin

    Energy Technology Data Exchange (ETDEWEB)

    Komura, Jun-ichiro, E-mail: junkom@med.tohoku.ac.jp [Department of Cell Biology, Tohoku University Graduate School of Medicine, Sendai 980-8575 (Japan); Ikehata, Hironobu [Department of Cell Biology, Tohoku University Graduate School of Medicine, Sendai 980-8575 (Japan); Mori, Toshio [Radioisotope Research Center, Nara Medical University, Kashihara, Nara 634-8521 (Japan); Ono, Tetsuya [Department of Cell Biology, Tohoku University Graduate School of Medicine, Sendai 980-8575 (Japan)

    2012-03-10

    During mitosis, chromatin is highly condensed, and activities such as transcription and semiconservative replication do not occur. Consequently, the condensed condition of mitotic chromatin is assumed to inhibit DNA metabolism by impeding the access of DNA-transacting proteins. However, about 40 years ago, several researchers observed unscheduled DNA synthesis in UV-irradiated mitotic chromosomes, suggesting the presence of excision repair. We re-examined this subject by directly measuring the removal of UV-induced DNA lesions by an ELISA and by a Southern-based technique in HeLa cells arrested at mitosis. We observed that the removal of (6-4) photoproducts from the overall genome in mitotic cells was as efficient as in interphase cells. This suggests that global genome repair of (6-4) photoproducts is fully functional during mitosis, and that the DNA in mitotic chromatin is accessible to proteins involved in this mode of DNA repair. Nevertheless, not all modes of DNA repair seem fully functional during mitosis. We also observed that the removal of cyclobutane pyrimidine dimers from the dihydrofolate reductase and c-MYC genes in mitotic cells was very slow. This suggests that transcription-coupled repair of cyclobutane pyrimidine dimers is compromised or non-functional during mitosis, which is probably the consequence of mitotic transcriptional repression. -- Highlights: Black-Right-Pointing-Pointer Global genome repair of (6-4) photoproducts is fully active in mitotic cells. Black-Right-Pointing-Pointer DNA in condensed mitotic chromatin does not seem inaccessible or inert. Black-Right-Pointing-Pointer Mitotic transcriptional repression may impair transcription-coupled repair.

  18. Effect of the spectral range of a UV lamp on the production of cyclobutane pyrimidine dimers in human skin in situ.

    Science.gov (United States)

    Snellman, Erna; Strozyk, Malgorzata; Segerbäck, Dan; Klimenko, Taras; Hemminki, Kari

    2003-12-01

    Ultraviolet (UV) irradiation has a broad spectrum of biological effects and a capacity to initiate skin carcinogenesis through DNA damage. The effect of different wave bands of UV light on the production of DNA damage in human skin in situ was studied with a broadband UV-B lamp TL-12 and a narrowband UV-B lamp TL-01. Eight psoriasis patients participated in the study. Their minimal erythema dose was assessed separately for the two UV-B wave band ranges. Test areas of buttock skin were irradiated with the two spectrally differing lamps using erythemally equivalent UV doses of 40 and 80 mJ/cm2 CIE (Commission International de I'Eclairage). Punch biopsies were taken from the irradiated areas, and UV-induced DNA lesions (cyclobutane pyrimidine dimers, CPDs) in the skin were analyzed with a 32P high-performance liquid chromatography postlabelling method. No UV source-dependent differences in the induced levels of CPDs were detected in this study. CPD production with broadband TL-12 and narrowband TL-01 UV-B lamps in situ did not differ when erythemally equivalent UV doses were used. The preliminary result needs to be confirmed in a larger study.

  19. In Vivo Spectrum of UVC-induced Mutation in Mouse Skin Epidermis May Reflect the Cytosine Deamination Propensity of Cyclobutane Pyrimidine Dimers.

    Science.gov (United States)

    Ikehata, Hironobu; Mori, Toshio; Yamamoto, Masayuki

    2015-11-01

    Although ultraviolet radiation (UVR) has a genotoxicity for inducing skin cancers, the skin may tolerate UVC component because the epidermal layer prevents this short wavelength range from passing through. Here, UVC genotoxicity for mouse skin was evaluated in terms of DNA damage formation and mutagenicity. UVC induced UVR photolesions and mutations remarkably in the epidermis but poorly in the dermis, confirming the barrier ability of the epidermis against shorter UVR wavelengths. Moreover, the epidermis itself responded to UVC mutagenicity with mutation induction suppression, which suppressed the mutant frequencies to a remarkably low, constant level regardless of UVC dose. The mutation spectrum observed in UVC-exposed epidermis showed a predominance of UV-signature mutation, which occurred frequently in 5'-TCG-3', 5'-TCA-3' and 5'-CCA-3' contexts. Especially, for the former two contexts, the mutations recurred at several sites with more remarkable recurrences at the 5'-TCG-3' sites. Comparison of the UVC mutation spectrum with those observed in longer UVR wavelength ranges led us to a mechanism that explains why the sequence context preference of UV-signature mutation changes according to the wavelength, which is based on the difference in the mCpG preference of cyclobutane pyrimidine dimer (CPD) formation among UVR ranges and the sequence context-dependent cytosine deamination propensity of CPD. © 2015 The American Society of Photobiology.

  20. Immunological detection of UV induced cyclobutane pyrimidine dimers and (6-4) photoproducts in DNA from reference bacteria and natural aquatic populations.

    Science.gov (United States)

    Kraft, Stephanie; Stephanie, Kraft; Obst, Ursula; Ursula, Obst; Schwartz, Thomas; Thomas, Schwartz

    2011-03-01

    UV light-caused DNA damage is a widespread field of study. As UV light has the biological effect of inactivating or killing bacteria, it is used for water disinfection. Due to this application, it is important to study the DNA damage efficiencies and regeneration capacities in bacteria after UV irradiation. Two monoclonal antibodies, anti-CPD and anti-(6-4) PP, were applied for an immunoassay of UV-induced DNA modifications. Cyclobutane pyrimidine dimer (CPD) and 6-4 photoproduct (6-4 PP) were detected in the reference bacteria Pseudomonas aeruginosa and Enterococcus faecium, and in natural water communities. The antibody-mediated detection signals increased with the UV doses from 100-400J/m(2). Here, the CPD-specific signals were stronger than the (6-4) PP-specific signals. These immunological results were in accordance with parallel cultivation experiments. All UV-irradiated bacteria showed a reduction of their growth rate depending on UV application by several orders of magnitudes. The immunoassay was also applied to three types of natural aquatic habitats with different cell densities. Besides artificial UV irradiation, it was possible to visualize natural sunlight effects on these natural bacterial communities. Light-dependent and dark repair processes were distinguished using the established immunological assays. The antibody-mediated analyses presented are fast methods to detect UV-induced DNA lesions and repair capacities in selected bacterial species as well as in entire natural mixed populations. Copyright © 2011 Elsevier B.V. All rights reserved.

  1. Solution structure of the DNA decamer duplex containing a 3′-T·T base pair of the cis–syn cyclobutane pyrimidine dimer: implication for the mutagenic property of the cis–syn dimer

    OpenAIRE

    Lee, Joon-Hwa; Choi, Yun-Jeong; Choi, Byong-Seok

    2000-01-01

    The cis–syn dimer is the major DNA photoproduct produced by UV irradiation. In order to determine the origin of the mutagenic property of the cis–syn dimer, we used NMR restraints and molecular dynamics to determine the solution structure of a DNA decamer duplex containing a wobble pair between the 3′-T of the cis–syn dimer and the opposite T residue (CS/TA duplex). The solution structure of the CS/TA duplex revealed that the 3′-T·T base pair of the cis–syn dimer had base pair geometry that w...

  2. Resistance of the genome of Escherichia coli and Listeria monocytogenes to irradiation evaluated by the induction of cyclobutane pyrimidine dimers and 6-4 photoproducts using gamma and UV-C radiations

    Science.gov (United States)

    Beauchamp, S.; Lacroix, M.

    2012-08-01

    The effect of gamma and UV-C irradiation on the production of cyclobutane pyrimidine dimers (CPDs) and 6-4 photoproducts (6-4 PPs) in DNA was investigated to compare the natural resistance of the genome of a Gram-positive bacterium and a Gram-negative bacterium against irradiation. Solution of pure DNA and bacterial strains Listeria monocytogenes and Escherichia coli were irradiated using gamma and UV-C rays. Extracted DNA from bacteria and pure DNA samples were then analysed by ELISA using anti-CPDs and anti-6-4 PPs monoclonal antibodies. The results show that gamma rays, as well as UV-C rays, induce the formation of CPDs and 6-4 PPs in DNA. During UV-C irradiation, the three samples showed a difference in their sensitivity against formation of CPDs (P≤0.05). Pure DNA was the most sensitive while the genome of L. monocytogenes was the most resistant. Also during UV-C irradiation, the genome of L. monocytogenes was the only one to show a significant resistance against formation of 6-4 PPs (P≤0.05). During gamma irradiation, for both types of lesion, pure DNA and the genome of E. coli did not show significant difference in their sensitivity (P>0.05) while the genome of L. monocytogenes showed a resistance against formation of CPDs and 6-4 PPs.

  3. Inducible nucleotide excision repair (NER) of UV-induced cyclobutane pyrimidine dimers in the cell cycle of the budding yeast Saccharomyces cerevisiae: evidence that inducible NER is confined to the G1 phase of the mitotic cell cycle

    International Nuclear Information System (INIS)

    Scott, A.D.; Waters, R.

    1997-01-01

    We previously reported on an inducible component of nucleotide excision repair in Saccharomyces cerevisiae that is controlled by the RAD16 gene. Here we describe a study of this event at the MAT alpha and HML alpha mating-type loci and on the transcribed (TS) and nontranscribed (NTS) strands of the RAD16 gene. Events were examined at various stages of the mitotic cycle in cells synchronised by centrifugal elutriation. Repair of cyclobutane pyrimidine dimers (CPDs) following a single UV dose does not vary significantly in different stages of the mitotic cell cycle. CPDs are removed more rapidly from the transcriptionally active MAT alpha locus than from the silent HML alpha locus, and the TS of RAD16 is repaired faster than the NTS in all stages of the cycle following a single UV irradiation. Enhanced excision of CPDs at MAT alpha and HML alpha can be induced only in the G1 and early S stages of the cell cycle. Here prior irradiation of cells with 25 J/m 2 enhances the removal of CPDs following a second UV dose of 70 J/m 2 . The level of enhancement of repair does not differ significantly between MAT alpha and HML alpha in G1. Enhanced removal of CPDs is absent when cells receive the inducing dose in late S or G2/M. Repair of CPDs in both strands of RAD16 is similarly enhanced only if cells receive the initial irradiation in G1 and early S. The level of enhanced removal of CPDs is not significantly different in the TS and NTS of RAD16 either in asynchronous cells or in cells preirradiated in G1 and early S. It has been shown by others that UV-induced expression of RAD16 remains at high levels if cells are held in G1 by treatment with alpha factor. Therefore the increase in RAD16 transcript levels in G1 may be responsible for the ability to enhance NER solely in this stage of the cell cycle

  4. Electron scattering from pyrimidine

    International Nuclear Information System (INIS)

    Colmenares, Rafael; Fuss, Martina C; García, Gustavo; Oller, Juan C; Muñoz, Antonio; Blanco, Francisco; Almeida, Diogo; Limão-Vieira, Paulo

    2014-01-01

    Electron scattering from pyrimidine (C 4 H 4 N 2 ) was investigated over a wide range of energies. Following different experimental and theoretical approaches, total, elastic and ionization cross sections as well as electron energy loss distributions were obtained.

  5. Neutron scattering in dimers

    DEFF Research Database (Denmark)

    Gudel, H. U.; Furrer, A.; Kjems, Jørgen

    1986-01-01

    Insulating compounds containing dimers of transition metal and rare earth ions have been studied by inelastic neutron scattering (INS). Energy splittings can be directly determined, and the corresponding parameters are easily extracted from the experimental data. The intensities of dimer...... excitations are modulated by an interference term reflecting the distance between the magnetic ions within the dimers. The INS technique is particularly powerful for the study of effects like: temperature dependence of exchange, the role of biquadratic exchange, the combination of crystal-field and exchange...

  6. Pyrimidine-pyridine ring interconversion

    NARCIS (Netherlands)

    Plas, van der H.C.

    2003-01-01

    This chapter discusses the pyrimidine-to-pyridine ring transformation and pyridine-to-pyrimidine ring transformation. In nucleophile-induced pyrimidine-to-pyridine rearrangements, two types of reactions can be distinguished depending on the structure of the nucleophile: (1) reactions in which the

  7. Copper Pyrimidine based MOFs

    Indian Academy of Sciences (India)

    Cl..Cu.. interactions but restricted ..Cu..N N..Cu interacations. Supramolecular isomers of Br and I are reported for the first time in this paper. [Cu2I(pdz)X2]. Figure S18. Self assembly of the simultaneous presence of tecton {Cu(sol)3X} and {Cu(pdz)(sol)2X} result in [Cu2I(pdz)X2]. 1. Table S3. Copper Pyrimidine based MOFs ...

  8. Structure of the dimeric form of CTP synthase from Sulfolobus solfataricus

    DEFF Research Database (Denmark)

    Lauritsen, Iben; Willemoës, Martin; Jensen, Kaj Frank

    2011-01-01

    CTP synthase catalyzes the last committed step in de novo pyrimidine-nucleotide biosynthesis. Active CTP synthase is a tetrameric enzyme composed of a dimer of dimers. The tetramer is favoured in the presence of the substrate nucleotides ATP and UTP; when saturated with nucleotide, the tetramer c....... solfataricus CTP synthase according to a structural alignment with the E. coli enzyme all have large thermal parameters in the dimeric form. Furthermore, they are seen to undergo substantial movement upon tetramerization....

  9. Role of cyclobutane dimers in UV-denaturation of DNA

    International Nuclear Information System (INIS)

    Zavil'gel'skij, G.B.; Zuev, A.V.

    1978-01-01

    UV irradiation of double-stranded DNA produces local denatured regions. The evidence presented indicates that these single-stranded regions arise from photoproducts other than pyrimidine dimers. The irradiation of T2 DNA at 8x10 4 erg/mm 2 (254 nm) produces 6-8% thymine dimers, amd Tsub(mel) drops by 12-14 deg C, accompanied by a significant broadening of the transition profile. The kinetics of denatured region formation and lowering Tsub(mel) corresponds to that of formation of crosslinkages and differs markedly from the kinetics of formation of cyclobutane pyrimidine dimers. Treatment of UV-irradiated DNA with light in the presence of yeast photoreactivating enzyme monomerizes almost all thymine dimers but does not change the Tsub(mel). Local denatured regions are detected in UV-irradiated DNA and are absent from AcPhM-sensibilized DNA, which contains 20-25% thymine dimers, as determined by the accridine orange fluorescence technique. S1 nuclease from Aspergillis oryzae produces single-strand breaks in UV-irradiated DNA of phage PM2 but is not active on AcPhM-treated PM2 DNA, which contains about 50 thymine dimers. It is supposed that the formation of a cyclobutane dimer only weakens the hydrogen bonds in the AT base pair rather than breaks them. Local denatured regions are thought to arise from the accumulation in UV-irradiated DNA (254 nm) of the sufficient number of photoproducts with impaired ability to base pairing

  10. A Sustainable Multicomponent Pyrimidine Synthesis.

    Science.gov (United States)

    Deibl, Nicklas; Ament, Kevin; Kempe, Rhett

    2015-10-14

    Since alcohols are accessible from indigestible biomass (lignocellulose), the development of novel preferentially catalytic reactions in which alcohols are converted into important classes of fine chemicals is a central topic of sustainable synthesis. Multicomponent reactions are especially attractive in organic chemistry as they allow the synthesis of large libraries of diversely functionalized products in a short time when run in a combinatorial fashion. Herein, we report a novel, regioselective, iridium-catalyzed multicomponent synthesis of pyrimidines from amidines and up to three (different) alcohols. This reaction proceeds via a sequence of condensation and dehydrogenation steps which give rise to selective C-C and C-N bond formations. While the condensation steps deoxygenate the alcohol components, the dehydrogenations lead to aromatization. Two equiv of hydrogen and water are liberated in the course of the reactions. PN5P-Ir-pincer complexes, recently developed in our laboratory, catalyze this sustainable multicomponent process most efficiently. A total of 38 different pyrimidines were synthesized in isolated yields of up to 93%. Strong points of the new protocol are its regioselectivity and thus the immediate access to pyrimidines that are highly and unsymmetrically decorated with alkyl or aryl substituents. The combination of this novel protocol with established methods for converting alcohols to nitriles now allows to selectively assemble pyrimidines from four alcohol building blocks and 2 equiv of ammonia.

  11. Isotopically labelled pyrimidines and purines

    International Nuclear Information System (INIS)

    Balaban, A.T.; Bally, I.

    1987-01-01

    Among the three diazines, pyrimidine is by far the most important one because its derivatives uracil, thymine and cytosine are constituents of the ubiquitous deoxynucleic acids (DNA) and ribonucleic acids (RNA). Other derivatives of pyrimidine without condensed rings include barbiturates, alloxan, orotic acid and thiamine or vitamin B 1 . From the polycyclic derivatives of pyrimidine such as pteridine, alloxazine, and purine, the latter, through its derivatives adenine and guanine complete the list of bases which occur in DNA and RNA: in addition, other purine derivatives such as hypoxanthine, xanthine, theobromine, theophylline, caffeine and uric acid are important natural products with biological activity. The paper presents methods for preparing isotopically labeled pyrimidines as well as purine derivatives. For convenience, the authors describe separately carbon-labeled with radioisotopes 11 C (T 1/2 = 20.3 min) and 14 C (T 1/2 = 5736 years) or the stable isotope 13 C (natural abundance 1.1%) and then hydrogen-labeled systems with the radioisotope 3 H ≡ T (T 1/2 = 12.346 years) or with the stable isotope 2 H ≡ D (natural abundance 0.015%). We do not separate stable from radioactive isotopes because the synthetic methods are identical for the same element; however, the introduction of hydrogen isotopes into organic molecules is often performed by reactions such as isotope exchange which cannot take place in the case of carbon isotopes

  12. Embryo splitting

    OpenAIRE

    Karl Illmensee; Mike Levanduski

    2010-01-01

    Mammalian embryo splitting has successfully been established in farm animals. Embryo splitting is safely and efficiently used for assisted reproduction in several livestock species. In the mouse, efficient embryo splitting as well as single blastomere cloning have been developed in this animal system. In nonhuman primates embryo splitting has resulted in several pregnancies. Human embryo splitting has been reported recently. Microsurgical embryo splitting under Institutional Review Board appr...

  13. Observation of covalent and electrostatic bonds in nitrogen-containing polycyclic ions formed by gas phase reactions of the benzene radical cation with pyrimidine.

    Science.gov (United States)

    Attah, Isaac Kwame; Soliman, Abdel-Rahman; Platt, Sean P; Meot-Ner Mautner, Michael; Aziz, Saaudallah G; Samy El-Shall, M

    2017-03-01

    Polycyclic aromatic hydrocarbons (PAHs) and polycyclic aromatic nitrogen heterocyclics (PANHs) are present in ionizing environments, including interstellar clouds and solar nebulae, where their ions can interact with neutral PAH and PANH molecules leading to the formation of a variety of complex organics including large N-containing ions. Herein, we report on the formation of a covalently-bonded (benzene·pyrimidine) radical cation dimer by the gas phase reaction of pyrimidine with the benzene radical cation at room temperature using the mass-selected ion mobility technique. No ligand exchange reactions with benzene and pyrimidine are observed indicating that the binding energy of the (benzene·pyrimidine)˙ + adduct is significantly higher than both the benzene dimer cation and the proton-bound pyrimidine dimer. The (benzene·pyrimidine)˙ + adduct shows thermal stability up to 541 K. Thermal dissociation of the (C 6 D 6 ·C 4 H 4 N 2 )˙ + adduct at temperatures higher than 500 K produces C 4 H 4 N 2 D + (m/z 82) suggesting the transfer of a D atom from the C 6 D 6 moiety to the C 4 H 4 N 2 moiety before the dissociation of the adduct. Mass-selected ion mobility of the (benzene·pyrimidine)˙ + dimer reveals the presence of two families of isomers formed by electron impact ionization of the neutral (benzene·pyrimidine) dimer. The slower mobility peak corresponds to a non-covalent family of isomers with larger collision cross sections (76.0 ± 1.8 Å 2 ) and the faster peak is consistent with a family of covalent isomers with more compact structures and smaller collision cross sections (67.7 ± 2.2 Å 2 ). The mobility measurements at 509 K show only one peak corresponding to the family of stable covalently bonded isomers characterized by smaller collision cross sections (66.9 ± 1.9 Å 2 at 509 K). DFT calculations at the M06-2X/6-311++G** level show that the most stable (benzene·pyrimidine)˙ + isomer forms a covalent C-N bond with a binding energy of 49

  14. Embryo splitting

    Directory of Open Access Journals (Sweden)

    Karl Illmensee

    2010-04-01

    Full Text Available Mammalian embryo splitting has successfully been established in farm animals. Embryo splitting is safely and efficiently used for assisted reproduction in several livestock species. In the mouse, efficient embryo splitting as well as single blastomere cloning have been developed in this animal system. In nonhuman primates embryo splitting has resulted in several pregnancies. Human embryo splitting has been reported recently. Microsurgical embryo splitting under Institutional Review Board approval has been carried out to determine its efficiency for blastocyst development. Embryo splitting at the 6–8 cell stage provided a much higher developmental efficiency compared to splitting at the 2–5 cell stage. Embryo splitting may be advantageous for providing additional embryos to be cryopreserved and for patients with low response to hormonal stimulation in assisted reproduction programs. Social and ethical issues concerning embryo splitting are included regarding ethics committee guidelines. Prognostic perspectives are presented for human embryo splitting in reproductive medicine.

  15. Disorders of purines and pyrimidines.

    Science.gov (United States)

    Kelley, Roger E; Andersson, Hans C

    2014-01-01

    Disorders of purine and pyrimidine metabolism can result in an array of clinical manifestations including neurologic manifestations. The most commonly cited disorder, in the neurologic realm, is Lesch-Nyhan syndrome which presumably reflects its distinctive feature of self-mutilation. Expansion of our knowledge with molecular genetic methodology has helped to better identify and characterize mutations such as those which occur with the enzyme hypoxanthine guanine phosphoribosyltransferase (HPRT), and this has enhanced our understanding of phenotypical expression of Lesch-Nyhan syndrome and Lesch-Nyhan variants. It is hoped that further elucidation of DNA coding regions and messenger RNA expression will lead to the potential for gene therapy to correct these inborn errors of purine and pyrimidine metabolism. © 2014 Elsevier B.V. All rights reserved.

  16. DNA repair in B. subtilis: an inducible dimer-specific W-reactivation system

    International Nuclear Information System (INIS)

    Fields, P.I.; Yasbin, R.E.

    1982-01-01

    The W-reactivation system of Bacillus subtilis can repair pyrimidine dimers in bacteriophage DNA. This inducible repair system can be activated by treatment of the bacteria with uv, alkylating agents, cross-linking agents and gamma irradiation. However, bacteriophage treated with agents other than those that cause pyrimidine dimers to be produced was not repaired by this unique form of W-reactivation. In contrast, the W-reactivation system of Escherichia coli can repair a variety of damages placed in the bacteriophage DNA

  17. Polyurethane Foams with Pyrimidine Rings

    Directory of Open Access Journals (Sweden)

    Kania Ewelina

    2014-09-01

    Full Text Available Oligoetherols based on pyrimidine ring were obtained upon reaction of barbituric acid with glycidol and alkylene carbonates. These oligoetherols were then used to obtain polyurethane foams in the reaction of oligoetherols with isocyanates and water. The protocol of foam synthesis was optimized by the choice of proper kind of oligoetherol and synthetic composition. The thermal resistance was studied by dynamic and static methods with concomitant monitoring of compressive strength. The polyurethane foams have similar physical properties as the classic ones except their enhanced thermal resistance. They stand long-time heating even at 200°C. Moreover thermal exposition of foams results generally in increase of their compressive strength.

  18. pyrimidines

    Indian Academy of Sciences (India)

    Cg (centroid of the C11c-C16c ring) interaction is also observed between molecules 1a & 1c. The crystal structure of compound 2 is stabi- lized by intermolecular N-H...N and C-H...O inter- actions. There are three types of N-H...N interac- tions, in which two interactions N3a-H3a1...N2b, and. N3b-H3b2...N4a result in sheet ...

  19. Purine and pyrimidine metabolism in man V

    International Nuclear Information System (INIS)

    Nyhan, W.L.; Thompson, L.F.; Watts, R.W.E.

    1986-01-01

    This book comprises the proceedings of the Fifth International Symposium on Human Purine and Pyrimidine Metabolism. Its papers are organized under the following categories: adenosine receptors; purine receptors and the central nervous system; nucleoside and base transport; studies with antimetabolites; deoxynucleotide and nucleoside toxicity and metabolism; enzymes; purine and pyrimidine metabolism during lymphocyte differentiation; purine metabolism in skeletal muscle; purine nucleotide metabolism in the heart; purine and pyrimidine metabolism in primary cell cultures and in parasites; nucleoside kinases and drug activation; phosphoribosylpyrophosphate; S-adenosylmethionine metabolism; and the metabolic effects of interferon

  20. Crystal structure of 4-allylsulfanyl-1H-pyrazolo[3,4-d]pyrimidine

    Directory of Open Access Journals (Sweden)

    Mohammed El Fal

    2014-09-01

    Full Text Available In the title compound, C8H8N4S, the pyrazolo[3,4-d]pyrimidine ring system is essentially planar, with a maximum deviation from the mean plane of 0.025 (3 Å. The allyl group is disordered over two sites in a 0.512 (6:0.488 (6 ratio. In the crystal, molecules are linked by pairs of N—H...N hydrogen bonds, forming inversion dimers with an R22(8 graph-set motif.

  1. Liquid crystal dimers

    CERN Document Server

    Kumar Pal, Santanu

    2017-01-01

    This book covers in-depth discussion of design principles, synthesis and thermal behavior of all types of liquid crystal (LC) dimers. The text presents recent advances in the field of LC dimers consisting of different mesogenic units such as calamitic, discotic and bent-core molecules. It starts with a chapter on the introduction of liquid crystal dimers, including their odd-even behavior, basic classification of dimers and common mesophases in dimers. The text shows how the molecular architectures are being used to develop new materials to study a range of interesting phenomena such as the biaxial nematic phase containing rod-like and disc-like mesogenic units. Finally, the text presents perspectives related to technological relevance of these dimers such as dopants in LC display mixtures exhibiting faster relaxation time, strong flexoelectric coupling and others to effect control over the properties of these materials.

  2. Splitting Descartes

    DEFF Research Database (Denmark)

    Schilhab, Theresa

    2007-01-01

    Kognition og Pædagogik vol. 48:10-18. 2003 Short description : The cognitivistic paradigm and Descartes' view of embodied knowledge. Abstract: That the philosopher Descartes separated the mind from the body is hardly news: He did it so effectively that his name is forever tied to that division....... But what exactly is Descartes' point? How does the Kartesian split hold up to recent biologically based learning theories?...

  3. Reduced repair of non-dimer photoproducts in a gene transfected into xeroderma pigmentosum cells

    International Nuclear Information System (INIS)

    Protic-Sabljic, Miroslava; Kraemer, K.H.

    1986-01-01

    Cells from patients with the sun sensitive cancer-prone disease, xeroderma pigmentosum (XP) have defective repair of UV damaged DNA with reduced excision of the major photoproduct, the cyclobutane type pyrimidine dimer. Other (non-dimer) photoproducts, have recently been implicated in UV mutagenesis. Utilizing an expression vector host cell reactivation assay, UV damaged transfecting DNA that was treated by in vitro photoreactivation to reverse pyrimidine dimers while not altering other photoproducts was studied. It was found that the reduced expression of a UV damaged transfecting plasmid in XP complementation group A cells is only partially reversed by photoreactivation. E. coli photolyase treatment of pSV2catSVgpt exposed to 100 or 200 J m -2 of 254 nm radiation removed 99% of the T4 endonuclease V sensitive sites. Transfection of XP12BE(SV40) cells with photoreactivated pSV2catSVgpt showed residual inhibition corresponding to 25 to 37% of the lethal hits to the cat gene. This residual inhibition corresponds to the fraction of non-dimer photoproducts induced by UV. This result implies that XP12BE(SV40) cells do not repair most of the non-dimer photoproducts in DNA. (author)

  4. Neurological disorders of purine and pyrimidine metabolism.

    Science.gov (United States)

    Micheli, Vanna; Camici, Marcella; Tozzi, Maria G; Ipata, Piero L; Sestini, Sylvia; Bertelli, Matteo; Pompucci, Giuseppe

    2011-01-01

    Purines and pyrimidines, regarded for a long time only as building blocks for nucleic acid synthesis and intermediates in the transfer of metabolic energy, gained increasing attention since genetically determined aberrations in their metabolism were associated clinically with various degrees of mental retardation and/or unexpected and often devastating neurological dysfunction. In most instances the molecular mechanisms underlying neurological symptoms remain undefined. This suggests that nucleotides and nucleosides play fundamental but still unknown roles in the development and function of several organs, in particular central nervous system. Alterations of purine and pyrimidine metabolism affecting brain function are spread along both synthesis (PRPS, ADSL, ATIC, HPRT, UMPS, dGK, TK), and breakdown pathways (5NT, ADA, PNP, GCH, DPD, DHPA, TP, UP), sometimes also involving pyridine metabolism. Explanations for the pathogenesis of disorders may include both cellular and mitochondrial damage: e.g. deficiency of the purine salvage enzymes hypoxanthine-guanine phosphoribosyltransferase and deoxyguanosine kinase are associated to the most severe pathologies, the former due to an unexplained adverse effect exerted on the development and/or differentiation of dopaminergic neurons, the latter due to impairment of mitochondrial functions. This review gathers the presently known inborn errors of purine and pyrimidine metabolism that manifest neurological syndromes, reporting and commenting on the available hypothesis on the possible link between specific enzymatic alterations and brain damage. Such connection is often not obvious, and though investigated for many years, the molecular basis of most dysfunctions of central nervous system associated to purine and pyrimidine metabolism disorders are still unexplained.

  5. Structures of DNA containing psoralen crosslink and thymine dimer

    International Nuclear Information System (INIS)

    Kim, S.H.; Pearlman, D.A.; Holbrook, S.R.; Pirkle, D.

    1985-01-01

    UV irradiation by itself or in conjunction with other chemicals can cause covalent damages to DNA in living cells. To overcome the detrimental effect of DNA damage, cells developed a repair mechanism by which damaged DNA is repaired. In the absence of such repair, cell malfunction or cell death can occur. Two most studied radiation-induced DNA damage are thymine dimer formation by UV irradiation and psoralen crosslink by combination of psoralens and UV: In the former, two adjacent thymine bases on a strand of DNA are fused by forming cyclobutane ring, and in the latter, one pyrimidine on one DNA strand is crosslinked to another pyrimidine on the other strand via a psoralen. The authors' objective is to deduce the structure of DNA segment which contains a psoralen crosslink or a thymine dimer using the combination of results of X-ray crystallographic studies, molecular model building, and energy minimization. These structural features may be important for understanding the biological effects of such damages and for the recognition by the repair enzymes

  6. 2-Ethynylpyridine dimers

    DEFF Research Database (Denmark)

    Bakarić, Danijela; Spanget-Larsen, Jens

    2018-01-01

    are used to study possible 2-EP dimer structures as well as their distribution in an inert solvent such as tetrachloroethene. Experimentally, the ≡C–H stretching vibration of the 2-EPmonomer absorbs close to 3300 cm−1, whereas a broad band withmaximum around 3215 cm−1 emerges as the concentration rises...... model with counterpoise correction predict that the two most stable dimers are of the pi-stacked variety, closely followed by dimers with intermolecular ≡C–H···N hydrogen bonding; the predicted red shifts of the ≡C–H stretching wavenumbers due to hydrogen bonding are in the range 54 – 120 cm–1...

  7. Dimers in nucleating vapors

    Science.gov (United States)

    Lushnikov, A. A.; Kulmala, M.

    1998-09-01

    The dimer stage of nucleation may affect considerably the rate of the nucleation process at high supersaturation of the nucleating vapor. Assuming that the dimer formation limits the nucleation rate, the kinetics of the particle formation-growth process is studied starting with the definition of dimers as bound states of two associating molecules. The partition function of dimer states is calculated by summing the Boltzmann factor over all classical bound states, and the equilibrium population of dimers is found for two types of intermolecular forces: the Lennard-Jones (LJ) and rectangular well+hard core (RW) potentials. The principle of detailed balance is used for calculating the evaporation rate of dimers. The kinetics of the particle formation-growth process is then investigated under the assumption that the trimers are stable with respect to evaporation and that the condensation rate is a power function of the particle mass. If the power exponent λ=n/(n+1) (n is a non-negative integer), the kinetics of the process is described by a finite set of moments of particle mass distribution. When the characteristic time of the particle formation by nucleation is much shorter than that of the condensational growth, n+2 universal functions of a nondimensional time define the kinetic process. These functions are calculated for λ=2/3 (gas-to-particle conversion in the free molecular regime) and λ=1/2 (formation of islands on surfaces).

  8. Radiation-induced tetramer-to-dimer transition of Escherichia coli lactose repressor

    International Nuclear Information System (INIS)

    Goffinont, S.; Davidkova, M.; Spotheim-Maurizot, M.

    2009-01-01

    The wild type lactose repressor of Escherichia coli is a tetrameric protein formed by two identical dimers. They are associated via a C-terminal 4-helix bundle (called tetramerization domain) whose stability is ensured by the interaction of leucine zipper motifs. Upon in vitro γ-irradiation the repressor losses its ability to bind the operator DNA sequence due to damage of its DNA-binding domains. Using an engineered dimeric repressor for comparison, we show here that irradiation induces also the change of repressor oligomerisation state from tetramer to dimer. The splitting of the tetramer into dimers can result from the oxidation of the leucine residues of the tetramerization domain.

  9. Glycine Transporter Dimers

    Science.gov (United States)

    Bartholomäus, Ingo; Milan-Lobo, Laura; Nicke, Annette; Dutertre, Sébastien; Hastrup, Hanne; Jha, Alok; Gether, Ulrik; Sitte, Harald H.; Betz, Heinrich; Eulenburg, Volker

    2015-01-01

    Different Na+/Cl−-dependent neurotransmitter transporters of the SLC6a family have been shown to form dimers or oligomers in both intracellular compartments and at the cell surface. In contrast, the glycine transporters (GlyTs) GlyT1 and -2 have been reported to exist as monomers in the plasma membrane based on hydrodynamic and native gel electrophoretic studies. Here, we used cysteine substitution and oxidative cross-linking to show that of GlyT1 and GlyT2 also form dimeric complexes within the plasma membrane. GlyT oligomerization at the cell surface was confirmed for both GlyT1 and GlyT2 by fluorescence resonance energy transfer microscopy. Endoglycosidase treatment and surface biotinylation further revealed that complex-glycosylated GlyTs form dimers located at the cell surface. Furthermore, substitution of tryptophan 469 of GlyT2 by an arginine generated a transporter deficient in dimerization that was retained intracellulary. Based on these results and GlyT structures modeled by using the crystal structure of the bacterial homolog LeuTAa, as a template, residues located within the extracellular loop 3 and at the beginning of transmembrane domain 6 are proposed to contribute to the dimerization interface of GlyTs. PMID:18252709

  10. Proficient synthesis of bioactive annulated pyrimidine derivatives: A review

    Directory of Open Access Journals (Sweden)

    Ajmal R. Bhat

    2017-11-01

    Full Text Available Syntheses of bioactive annulated pyrimidine derivatives are the most significant tasks in N-heterocyclic chemistry because these compounds have proved to be very attractive and useful for the design of new molecular frameworks of potential drugs with varying pharmacological activities. This review paper summarizes the one-pot multicomponent synthesis of annulated nitrogen- and oxygen-containing heterocycles, such as pyrano[2,3-d]pyrimidines, pyrido[2,3-d]pyrimidines and pyrido[2,3-d;5-6-d]dipyrimidines. The synthetic procedure is based on the chemistry of the domino Knoevenagel-Michael addition mechanism. Keywords: Pyrano[2,3-d]pyrimidines, Pyrido[2,3-d]pyrimidines, Pyrido[2,3-d;5-6-d]dipyrimidines, Barbituric acid/Thio-barbituric acid, Aromatic aldehydes, 6-aminouracil

  11. Dimeric form of peroxynitrite

    Science.gov (United States)

    Simon, K. V.; Tulub, A. V.

    2009-07-01

    The (ONOO)- anion, known as peroxynitrite, is characterized by a singlet spin state. A new stable dimer form of peroxynitrite [NO-O2]- in the triplet state at distances close to r(O-N) ≈ 2.885 Å between oxygen in the O2 structure and nitrogen has been established within the quantum-chemical CASSCF approximation. The vibrational motion of the dimer is significantly anharmonic; for the 16O and 14N isotopes, the differences in the energies of two neighboring levels correspond to frequencies of about 70-30 cm-1. The triplet dimer structure retains stability in the case of interaction with water molecules. The activation barriers caused by rearrangement of the peroxynitrite structure into the ground state of the NO{3/-} anion with the symmetry D 3 h are found.

  12. Ultraviolet-B-induced cyclobutane-pyrimidine dimer formation and repair in arctic marine macrophytes

    NARCIS (Netherlands)

    van de Poll, W.H.; Hanelt, D; Hoyer, K.; Buma, A.G.J.; Breeman, Arno

    2002-01-01

    The significance of ultraviolet-B radiation (UVBR: 280-315 nm)-induced DNA damage as a stress factor for Arctic marine macrophytes was examined in the Kongsfjord (Spitsbergen, 78degrees55.5'N, 11degrees56.0'E) in summer. UVBR penetration in the water column was monitored as accumulation of

  13. Selective amine catalysed steroidal dimerization

    Indian Academy of Sciences (India)

    steroid dimers in which carbon atoms comprise a ben- zene nucleus.6 A standard colour test for the presence of cholesterol is the formation of a green colour in concentrated sulphuric acid, and this was shown to be due to a polyenyl steroidal dimer carbocation.7–9 Many dimeric and oligomeric steroids exhibit interesting.

  14. Structural Insight into the Core of CAD, the Multifunctional Protein Leading De Novo Pyrimidine Biosynthesis.

    Science.gov (United States)

    Moreno-Morcillo, María; Grande-García, Araceli; Ruiz-Ramos, Alba; Del Caño-Ochoa, Francisco; Boskovic, Jasminka; Ramón-Maiques, Santiago

    2017-06-06

    CAD, the multifunctional protein initiating and controlling de novo biosynthesis of pyrimidines in animals, self-assembles into ∼1.5 MDa hexamers. The structures of the dihydroorotase (DHO) and aspartate transcarbamoylase (ATC) domains of human CAD have been previously determined, but we lack information on how these domains associate and interact with the rest of CAD forming a multienzymatic unit. Here, we prove that a construct covering human DHO and ATC oligomerizes as a dimer of trimers and that this arrangement is conserved in CAD-like from fungi, which holds an inactive DHO-like domain. The crystal structures of the ATC trimer and DHO-like dimer from the fungus Chaetomium thermophilum confirm the similarity with the human CAD homologs. These results demonstrate that, despite being inactive, the fungal DHO-like domain has a conserved structural function. We propose a model that sets the DHO and ATC complex as the central element in the architecture of CAD. Copyright © 2017 Elsevier Ltd. All rights reserved.

  15. Synthesis and comparing the antibacterial activities of pyrimidine ...

    Indian Academy of Sciences (India)

    triazol-3-yl)-6-methyl-4- phenyl pyrimidin-2(1H)-one have been synthesized. Among the synthesized derivatives, triazole substituted compounds have shown higher antibacterial inhibition when compared to the thiadiazole derivatives. All the.

  16. Alkane dimers interaction

    DEFF Research Database (Denmark)

    Ferrighi, Lara; Madsen, Georg Kent Hellerup; Hammer, Bjørk

    2010-01-01

    The interaction energies of a series of n-alkane dimers, from methane to decane, have been investigated with Density Functional Theory (DFT), using the MGGA-M06-L density functional. The results are compared both to the available wavefunction-based values as well as to dispersion corrected DFT...... values. The MGGA-M06-L density functional is a semi-local functional designed and has proven to provide accurate estimates of dispersion interactions for several systems at moderate computational cost. In the present application, it reproduces the trends obtained by the more expensive wavefunction...

  17. Low-energy positron scattering by pyrimidine

    Energy Technology Data Exchange (ETDEWEB)

    Barbosa, Alessandra Souza; Pastega, Diego F.; Bettega, Márcio H. F., E-mail: bettega@fisica.ufpr.br [Departamento de Física, Universidade Federal do Paraná, Caixa Postal 19044, 81531-990 Curitiba, Paraná (Brazil)

    2015-12-28

    This work reports elastic integral and differential cross sections for positron collisions with pyrimidine, for energies up to 20 eV. The cross sections were computed with the Schwinger multichannel method in the static plus polarization approximation. We also employed the Born closure procedure to account for the long range potential due to the permanent dipole moment of the molecule. Our results are compared with the experimental total cross section of Zecca et al. [J. Phys. B 43, 215204 (2010)], the experimental grand-total, quasi-elastic integral and differential cross section of Palihawadana et al. [Phys. Rev. A 88, 12717 (2013)]. We also compare our results with theoretical integral and differential cross sections obtained by Sanz et al. [Phys. Rev. A 88, 62704 (2013)] with the R-matrix and the independent atom model with screening-corrected additivity rule methods, and with the results computed by Franz and Gianturco [Phys. Rev. A 88, 042711 (2013)] using model correlation-polarization potentials. The agreement between the theory and the experiment is encouraging.

  18. Spin quantum tunneling via entangled states in a dimer of exchange coupled single-molecule magnets

    Science.gov (United States)

    Tiron, R.; Wernsdorfer, W.; Aliaga-Alcalde, N.; Foguet-Albiol, D.; Christou, G.

    2004-03-01

    A new family of supramolecular, antiferromagnetically exchange-coupled dimers of single-molecule magnets (SMMs) has recently been reported [W. Wernsdorfer, N. Aliaga-Alcalde, D.N. Hendrickson, and G. Christou, Nature 416, 406 (2002)]. Each SMM acts as a bias on its neighbor, shifting the quantum tunneling resonances of the individual SMMs. Hysteresis loop measurements on a single crystal of SMM-dimers have now established quantum tunneling of the magnetization via entangled states of the dimer. This shows that the dimer really does behave as a quantum-mechanically coupled dimer. The transitions are well separated, suggesting long coherence times compared to the time scale of the energy splitting. This result is of great importance if such systems are to be used for quantum computing. It also allows the measurement of the longitudinal and transverse superexchange coupling constants [Phys. Rev. Lett. 91, 227203 (2003)].

  19. Privileged substructure-based diversity-oriented synthesis pathway for diverse pyrimidine-embedded polyheterocycles

    DEFF Research Database (Denmark)

    Kim, Heejun; Thanh Tung, Truong; Park, Seung Bum

    2013-01-01

    A new diversity-oriented synthesis pathway for the fabrication of a pyrimidine-embedded polyheterocycles library was developed for potential interactions with diverse biopolymers. Five different pyrimidine-embedded core skeletons were synthesized from ortho-alkynylpyrimidine carbaldehydes...

  20. Selective amine catalysed steroidal dimerization

    Indian Academy of Sciences (India)

    of cholesterol is the formation of a green colour in concentrated sulphuric acid, and this was shown to be due to a polyenyl steroidal dimer carbocation.7–9 Many dimeric and oligomeric steroids exhibit interesting micellular, detergent and liquid crystal behaviour.10,11. Most of the steroidal dimmers are also well-known.

  1. Significance and Biological Importance of Pyrimidine in the Microbial World

    Directory of Open Access Journals (Sweden)

    Vinita Sharma

    2014-01-01

    Full Text Available Microbes are unique creatures that adapt to varying lifestyles and environment resistance in extreme or adverse conditions. The genetic architecture of microbe may bear a significant signature not only in the sequences position, but also in the lifestyle to which it is adapted. It becomes a challenge for the society to find new chemical entities which can treat microbial infections. The present review aims to focus on account of important chemical moiety, that is, pyrimidine and its various derivatives as antimicrobial agents. In the current studies we represent more than 200 pyrimidines as antimicrobial agents with different mono-, di-, tri-, and tetrasubstituted classes along with in vitro antimicrobial activities of pyrimidines derivatives which can facilitate the development of more potent and effective antimicrobial agents.

  2. Synthesis and Biological Activity of Reversed Pyrimidine Nucleosides

    Directory of Open Access Journals (Sweden)

    Nataša Župančić

    2015-03-01

    Full Text Available An efficient approach to reversed nucleosides which enables their synthesis in gram quantities is described. N-1′-Pyrimidine reversed nucleosides were prepared by treating of the sodium salt of pyrimidine bases with protected 5-tosyl ribose. Additionally, N-1′,N-3′-disubstituted reversed nucleosides were isolated in the condensation reactions with the 5-halogen pyrimidines. Using the Sonogashira coupling of 5′-iodouracil reversed nucleoside with ethynyltrimethyl silane gave 5′-ethynyl derivative which was further transformed into 5′-acetyl reversed nucleoside. Biological activity of deprotected reversed nucleosides was validated on the panel of six human carcinoma cell lines (HeLa, MIAPaCa2, Hep2, NCI-H358, CaCo-2, and HT-29. 5′-Iodouracil derivative displayed moderate growth inhibition activity against human colon carcinoma (CaCo-2 cells.

  3. 5-Bromo-2-[5-(4-nitrophenyl-3-phenyl-4,5-dihydro-1H-pyrazol-1-yl]pyrimidine

    Directory of Open Access Journals (Sweden)

    B. Kalluraya

    2009-12-01

    Full Text Available In the title pyrazoline compound, C19H14BrN5O2, the essentially planar pyrazoline and pyrimidine rings [maximum deviations = 0.013 (1 and 0.009 (1 Å, respectively] are inclined slightly to one another, making a dihedral angle of 10.81 (10°. The nitrobenzene unit is almost perpendicular to the attached pyrazoline ring, as indicated by the dihedral angle of 84.61 (8°. In the crystal structure, intermolecular C—H...N contacts link the molecules into dimers in an antiparallel manner. These dimers are further linked into one-dimensional chains along the b axis via C—H...O contacts. The crystal structure is consolidated by three different intermolecular π–π interactions [range of centroid–centroid distances = 3.5160 (11–3.6912 (11 Å].

  4. Nucleotide metabolism in Lactococcus lactis: Salvage pathways of exogenous pyrimidines

    DEFF Research Database (Denmark)

    Martinussen, Jan; Andersen, Paal Skytt; Hammer, Karin

    1994-01-01

    By measuring enzyme activities in crude extracts and studying the effect of toxic analogs (5-fluoropyrimidines) on cell growth, the metabolism of pyrimidines in Lactococcus lactis was analyzed. Pathways by which uracil, uridine, deoxyuridine, cytidine, and deoxycytidine are metabolized in L. lact...

  5. pyrimidines by Biginelli condensation and their antibacterial activities

    Indian Academy of Sciences (India)

    Indeno[1,2-d]pyrimidine-2-thiones; multicomponent reaction; microwave irradiation; antibacterial activity. 1. Introduction. In 1893 ... 0.76g) and substituted aromatic aldehyde. (0.01mole) were irradiated in microwave for 2–8min ...... Hill A E, Ladely S R and Fedorka- Cray P J 2008 Food. Borne Pathogen Dis. 5 7. 13. Nayak N ...

  6. Synthesis and molecular docking of pyrimidine incorporated novel ...

    Indian Academy of Sciences (India)

    APOORVA MISRA

    2018-03-09

    Mar 9, 2018 ... cDepartment of Pharmacy, Birla Institute of Technology and Science, Pilani, Pilani, Rajasthan 333 031, India. E-mail: ... novel pyrimidine derivatives using DMAD and DABCO catalyst under microwave conditions has been described. .... oration at reduced pressure to afford a mixture of colorless oil.

  7. Biotransformation, by Enterobacter agglomerans, of pyrimidine acyclonucleosides to acyclonucleotides.

    Science.gov (United States)

    Rutkowski, M; Korczak, E

    1992-06-15

    The ability of Enterobacter agglomerans to transform naturally occurring nucleosides into nucleotides has been utilized to transform newly synthesized pyrimidine acyclonucleosides into the corresponding acyclonucleotides. Unselected bacteria were used as the source of nucleoside phosphotransferase, the phosphate group donor being 4-nitrophenyl phosphate in the presence of Zn2+ ions. Optimal reaction conditions are outlined.

  8. IMIDAZO[1,2-a]PYRIMIDINE DERIVATIVES UNDER SOLVENT ...

    African Journals Online (AJOL)

    Preferred Customer

    The synthesis of benzo[4,5]imidazo[1,2-a]pyrimidine derivatives has been considered of great interest to organic chemists because of their pharmacological and therapeutic properties such as antineoplastic [1], protein kinase inhibitor [2], T cell activation [3], TIE-2 and/or VEGFR2 inhibitory activities [4]. The most common ...

  9. Synthesis of 7-arylethyl-5-arylpyrazolo pyrimidines through an aza ...

    Indian Academy of Sciences (India)

    ZHENG LI

    2017-10-09

    Oct 9, 2017 ... During the past decade, the synthesis of pyrazolo[1,5-a] pyrimidine derivatives and the investigation of their chemical and biological behavior have gained more importance due to pharmaceutical reasons.1,2 For exam- ple, the hypnotic drug Zaleplon (I),3 the anticancer agent Dinaciclib (II),4 the fungicide ...

  10. Synthesis of pyrimidine carboxamide derivatives catalyzed by uranyl

    African Journals Online (AJOL)

    2014-09-02

    (Received September 2, 2014; revised January 1, 2016). ABSTRACT. An efficient and simple method was developed for the synthesis pyrimidine-5-carboxamides using. UO2(NO3)2.6H2O catalyst under conventional and microwave irradiation. The synthesis of dihydropyrimidine using uranyl nitrate had shown many ...

  11. Synthesis and Antifungal Activities of Some Novel Pyrimidine Derivatives

    Directory of Open Access Journals (Sweden)

    Dequn Sun

    2011-06-01

    Full Text Available Three series of new pyrimidine derivatives were synthesized and their antifungal activities were evaluated in vitro against fourteen phytopathogenic fungi. The results indicated that most of the synthesized compounds possessed fungicidal activities and some of them are more potent than the control fungicides. Preliminary SAR was also discussed.

  12. Nucleotide metabolism in Lactococcus lactis: Salvage pathways of exogenous pyrimidines

    DEFF Research Database (Denmark)

    Martinussen, Jan; Andersen, Paal Skytt; Hammer, Karin

    1994-01-01

    By measuring enzyme activities in crude extracts and studying the effect of toxic analogs (5-fluoropyrimidines) on cell growth, the metabolism of pyrimidines in Lactococcus lactis was analyzed. Pathways by which uracil, uridine, deoxyuridine, cytidine, and deoxycytidine are metabolized in L. lactis...

  13. Coded Splitting Tree Protocols

    DEFF Research Database (Denmark)

    Sørensen, Jesper Hemming; Stefanovic, Cedomir; Popovski, Petar

    2013-01-01

    This paper presents a novel approach to multiple access control called coded splitting tree protocol. The approach builds on the known tree splitting protocols, code structure and successive interference cancellation (SIC). Several instances of the tree splitting protocol are initiated, each...... instance is terminated prematurely and subsequently iterated. The combined set of leaves from all the tree instances can then be viewed as a graph code, which is decodable using belief propagation. The main design problem is determining the order of splitting, which enables successful decoding as early...... as possible. Evaluations show that the proposed protocol provides considerable gains over the standard tree splitting protocol applying SIC. The improvement comes at the expense of an increased feedback and receiver complexity....

  14. Split Cord Malformations

    Directory of Open Access Journals (Sweden)

    Yurdal Gezercan

    2015-06-01

    Full Text Available Split cord malformations are rare form of occult spinal dysraphism in children. Split cord malformations are characterized by septum that cleaves the spinal canal in sagittal plane within the single or duplicated thecal sac. Although their precise incidence is unknown, split cord malformations are exceedingly rare and represent %3.8-5 of all congenital spinal anomalies. Characteristic neurological, urological, orthopedic clinical manifestations are variable and asymptomatic course is possible. Earlier diagnosis and surgical intervention for split cord malformations is associated with better long-term fuctional outcome. For this reason, diagnostic imaging is indicated for children with associated cutaneous and orthopedic signs. Additional congenital anomalies usually to accompany the split cord malformations. Earlier diagnosis, meticuolus surgical therapy and interdisciplinary careful evaluation and follow-up should be made for good prognosis. [Cukurova Med J 2015; 40(2.000: 199-207

  15. Isotope exchange reactions of the hydrogen H-5 of selected pyrimidine derivatives and the preparation of tritium-labeled pyrimidines

    Czech Academy of Sciences Publication Activity Database

    Dračínský, Martin; Jansa, Petr; Elbert, Tomáš

    2011-01-01

    Roč. 76, č. 12 (2011), s. 1567-1577 ISSN 0010-0765 R&D Projects: GA AV ČR KJB400550903; GA MŠk 1M0508 Institutional research plan: CEZ:AV0Z40550506 Keywords : isotopic labeling * NMR spectroscopy * nucleobases * pyrimidines Subject RIV: CC - Organic Chemistry Impact factor: 1.283, year: 2011

  16. Electron transfer with TD-Split, a linear response time-dependent method

    International Nuclear Information System (INIS)

    Bartell, Lizette A.; Reslan, Randa; Wall, Michael R.; Kennedy, Robert D.; Neuhauser, Daniel

    2011-01-01

    Graphical abstract: A simple method, time-dependent split (TD-Split) is developed for electron transfer through a TD evaluation of the lowest excitation energy from the ground state of the combined charged system. As an example, we study transfer between substituted fullerenes, primarily PCBM. Numerical linearization reduces the number of required iterations, and trends similar to experiment are found. Highlights: ► Electron transmission from charged-dimer transition-state excitation. ► Starting point: extended dimer charged (above-gap) homo, which is then excited. ► Excitation by real-time and linear response TD propagation. ► Analogous to two level system, but with full polarization included. ► TD-Split much larger than from static LUMO + 1–LUMO splitting for fullerene dimers. - Abstract: We present a simple method, time-dependent split (TD-Split) for A → B electron transfer by a TD evaluation of the lowest excitation energy from the ground state of the combined (AB) − system. As an example, we study transfer between substituted fullerenes, primarily PCBM. Electron transfer in such fullerene systems is important as it is often the bottleneck in organic solar cells. The TD-Split method is described in detail, including numerical linearization which reduces the number of required iterations, and comparison to other possible approaches. We also compare to other molecules such as C 60 Me 5 H, and find similar trends as experiment.

  17. Electromagnetic interaction of split-ring resonators: The role of separation and relative orientation.

    Science.gov (United States)

    Feth, Nils; König, Michael; Husnik, Martin; Stannigel, Kai; Niegemann, Jens; Busch, Kurt; Wegener, Martin; Linden, Stefan

    2010-03-29

    Extinction cross-section spectra of split-ring-resonator dimers have been measured at near-infrared frequencies with a sensitive spatial modulation technique. The resonance frequency of the dimer's coupled mode as well as its extinction cross-section and its quality factor depend on the relative orientation and separation of the two split-ring resonators. The findings can be interpreted in terms of electric and magnetic dipole-dipole interaction. Numerical calculations based on a Discontinuous Galerkin Time-Domain approach are in good agreement with the experiments and support our physical interpretation.

  18. Split Malcev algebras

    Indian Academy of Sciences (India)

    project of the Spanish Ministerio de Educación y Ciencia MTM2007-60333. References. [1] Calderón A J, On split Lie algebras with symmetric root systems, Proc. Indian. Acad. Sci (Math. Sci.) 118(2008) 351–356. [2] Calderón A J, On split Lie triple systems, Proc. Indian. Acad. Sci (Math. Sci.) 119(2009). 165–177.

  19. Comparative DFT study of van der Waals complexes: rare-gas dimers, alkaline-earth dimers, zinc dimer, and zinc-rare-gas dimers.

    Science.gov (United States)

    Zhao, Yan; Truhlar, Donald G

    2006-04-20

    Recent interest in the application of density functional theory prompted us to test various functionals for the van der Waals interactions in the rare-gas dimers, the alkaline-earth metal dimers, zinc dimer, and zinc-rare-gas dimers. In the present study, we report such tests for 18 DFT functionals, including both some very recent functionals and some well-established older ones. We draw the following conclusions based on the mean errors in binding energies and complex geometries: (1) B97-1 gives the best performance for predicting the geometry of rare-gas dimers, whereas M05-2X and B97-1 give the best energetics for rare-gas dimers. (2) PWB6K gives the best performance for the prediction of the geometry of the alkaline-earth metal dimers, zinc dimers, and zinc-rare-gas dimers. M05-2X gives the best energetics for the metal dimers, whereas B97-1 gives the best energetics for the zinc-rare-gas dimers. (3) The M05 functional is unique in providing good accuracy for both covalent transition-metal dimers and van der Waals metal dimers. (4) The combined mean percentage unsigned error in geometries and energetics shows that M05-2X and MPWB1K are the overall best methods for the prediction of van der Waals interactions in metal and rare-gas van der Waals dimers.

  20. Total cross sections for positron and electron scattering from pyrimidine

    International Nuclear Information System (INIS)

    Zecca, A; Chiari, L; Trainotti, E; GarcIa, G; Blanco, F; Brunger, M J

    2010-01-01

    In this paper we report original measurements of total cross sections for positron scattering from the important biomolecule pyrimidine. The energy range of these measurements was 0.3-45 eV, while the energy resolution was ∼260 meV. In addition, we report theoretical results, calculated within the independent atom-screened additivity rule (IAM-SCAR) formalism, for the corresponding electron impact total cross sections. In that case the energy range is 1-10 000 eV. Total cross sections are very important input data for codes that seek to simulate charged-particle tracks in matter, as they define the mean-free path between collisions. As the present data and computations are to the best of our knowledge the first total cross sections to be reported for either positron or electron scattering from pyrimidine, they fill an important void in our available knowledge in the literature.

  1. Pyrrolo[2,3-d]Pyrimidines as Kinase Inhibitors.

    Science.gov (United States)

    Musumeci, Francesca; Sanna, Monica; Grossi, Giancarlo; Brullo, Chiara; Fallacara, Anna Lucia; Schenone, Silvia

    2017-01-01

    The pyrrolo[2,3-d]pyrimidine nucleus is a deaza-isostere of adenine, the nitrogenous base of ATP, and is present in many ATP-competitive inhibitors of different kinases. In the last few years the number of articles and patents that have appeared involving this type of inhibitors has dramatically increased and some compounds have been approved for the treatment of inflammatory or myeloproliferative diseases. Other derivatives are currently being evaluated in clinical trials. This review deals with pyrrolo[2,3- d]pyrimidine derivatives active as kinase inhibitors that have been reported in the literature from 2011 to 2016, with a particular interest on the recently patented compounds. The molecules are classified depending on the inhibited kinase, focusing on their chemical structures. Copyright© Bentham Science Publishers; For any queries, please email at epub@benthamscience.org.

  2. New insights on pyrimidine signalling within the arterial vasculature

    DEFF Research Database (Denmark)

    Haanes, Kristian Agmund; Spray, Stine; Syberg, Susanne

    2016-01-01

    and relaxation in the coronary circulation and to establish whether P2Y receptors have different functions along the mouse coronary vascular tree. We tested stable pyrimidine analogues on isolated coronary arteries from P2Y2 and P2Y6 receptor KO mice in a myograph setup. In larger diameter segments of the left...... descending coronary artery (LAD) (lumen diameter~150μm) P2Y6 is the predominant contractile receptor for both UTP (uridine triphosphate) and UDP (uridine diphosphate) induced contraction. In contrast, P2Y2 receptors mediate endothelial-dependent relaxation. However, in smaller diameter LAD segments (lumen...... a biphasic response to the stable analogue UDPβS. Based on the changes in P2Y receptor functionality along the mouse coronary arterial vasculature, we propose that UTP can act as a vasodilator downstream of its release, after being degraded to UDP, without affecting the contractile pyrimidine receptors. We...

  3. Adventures in Holographic Dimer Models

    Energy Technology Data Exchange (ETDEWEB)

    Kachru, Shamit; /Stanford U., Phys. Dept. /SLAC; Karch, Andreas; /Washington U., Seattle; Yaida, Sho; /Stanford U., Phys. Dept.

    2011-08-12

    We abstract the essential features of holographic dimer models, and develop several new applications of these models. Firstly, semi-holographically coupling free band fermions to holographic dimers, we uncover novel phase transitions between conventional Fermi liquids and non-Fermi liquids, accompanied by a change in the structure of the Fermi surface. Secondly, we make dimer vibrations propagate through the whole crystal by way of double trace deformations, obtaining nontrivial band structure. In a simple toy model, the topology of the band structure experiences an interesting reorganization as we vary the strength of the double trace deformations. Finally, we develop tools that would allow one to build, in a bottom-up fashion, a holographic avatar of the Hubbard model.

  4. Synthesis and comparing the antibacterial activities of pyrimidine ...

    Indian Academy of Sciences (India)

    pyrimidin-2(1H)-one (Scheme 2), 3(a–j). Hydrazine carbothioamide 2a (3.05g, 0.01mol) was dissolved in 5mL conc. H2SO4. This solution was stirred at RT and left overnight. It was then poured in crushed ice. The resulting suspension was kept in ammoniacal water for 2h, filtered and purified by recrystallization from alcohol ...

  5. Synthesis and biological evaluation of some New pyrimidine derivatives

    Directory of Open Access Journals (Sweden)

    Firyal Weli Askar

    2017-06-01

    Full Text Available New pyrimidine derivatives comprising azo, schiff's bases, chalcones, and chromene ring moieties were prepared.The newly synthesized compounds have been established on the basis of their m.p., TLC, FT-IR, UV-Vis ,¹H-NMR data and element analysis. These compounds were screened for their antimicrobial and in vitro antioxidant properties. The results of this investigation revealed that these compounds are potent antimicrobial and antioxidant agent.

  6. Kinetics of DNA tile dimerization.

    Science.gov (United States)

    Jiang, Shuoxing; Yan, Hao; Liu, Yan

    2014-06-24

    Investigating how individual molecular components interact with one another within DNA nanoarchitectures, both in terms of their spatial and temporal interactions, is fundamentally important for a better understanding of their physical behaviors. This will provide researchers with valuable insight for designing more complex higher-order structures that can be assembled more efficiently. In this report, we examined several spatial factors that affect the kinetics of bivalent, double-helical (DH) tile dimerization, including the orientation and number of sticky ends (SEs), the flexibility of the double helical domains, and the size of the tiles. The rate constants we obtained confirm our hypothesis that increased nucleation opportunities and well-aligned SEs accelerate tile-tile dimerization. Increased flexibility in the tiles causes slower dimerization rates, an effect that can be reversed by introducing restrictions to the tile flexibility. The higher dimerization rates of more rigid tiles results from the opposing effects of higher activation energies and higher pre-exponential factors from the Arrhenius equation, where the pre-exponential factor dominates. We believe that the results presented here will assist in improved implementation of DNA tile based algorithmic self-assembly, DNA based molecular robotics, and other specific nucleic acid systems, and will provide guidance to design and assembly processes to improve overall yield and efficiency.

  7. Aspects of Split Supersymmetry

    CERN Document Server

    Arkani-Hamed, N; Giudice, Gian Francesco; Romanino, A

    2005-01-01

    We explore some fundamental differences in the phenomenology, cosmology and model building of Split Supersymmetry compared with traditional low-scale supersymmetry. We show how the mass spectrum of Split Supersymmetry naturally emerges from theories where the dominant source of supersymmetry breaking preserves an $R$ symmetry, characterize the class of theories where the unavoidable $R$-breaking by gravity can be neglected, and point out a new possibility, where supersymmetry breaking is directly communicated at tree level to the visible sector via renormalizable interactions. Next, we discuss possible low-energy signals for Split Supersymmetry. The absence of new light scalars removes all the phenomenological difficulties of low-energy supersymmetry, associated with one-loop flavor and CP violating effects. However, the electric dipole moments of leptons and quarks do arise at two loops, and are automatically at the level of present limits with no need for small phases, making them accessible to several ongo...

  8. Dynamics and energetics of Ge(001) dimers

    NARCIS (Netherlands)

    van Houselt, Arie; van Gastel, Raoul; Poelsema, Bene; Zandvliet, Henricus J.W.

    2006-01-01

    The dynamic behavior of surface dimers on Ge(001) has been studied by positioning the tip of a scanning tunneling microscope over single flip-flopping dimers and measuring the tunneling current as a function of time. We observe that not just symmetric, but also asymmetric appearing dimers exhibit

  9. Split Malcev algebras

    Indian Academy of Sciences (India)

    We study the structure of split Malcev algebras of arbitrary dimension over an algebraically closed field of characteristic zero. We show that any such algebras is of the form M = U + ∑ j I j with U a subspace of the abelian Malcev subalgebra and any I j a well described ideal of satisfying [ I j , I k ] = 0 if ≠ .

  10. Splitting of Comets

    Indian Academy of Sciences (India)

    Home; Journals; Resonance – Journal of Science Education; Volume 7; Issue 1. Splitting of Comets. Utpal Mukhopadhyay. General Article Volume 7 Issue 1 January 2002 pp 11-22. Fulltext. Click here to view fulltext PDF. Permanent link: http://www.ias.ac.in/article/fulltext/reso/007/01/0011-0022. Keywords. Cometary ...

  11. Repair of non-dimer DNA damages in ICB 2A frog cells exposed to solar-ultraviolet radiation in the UVB (290-320 nm) range

    International Nuclear Information System (INIS)

    Chao, C.C.K.

    1985-01-01

    The purpose of the research described in this dissertation was to investigate the repair and cellular consequences of non-dimer DNA damages induced by solar-UV irradiation of cultured I CR 2A (Rana pipiens) frog cells. Because this cell line is proficient in enzymatic photoreactivation, it was possible to induce a relatively pure population of non-dimer DNA photoproducts by exposure of cells to the Mylar-filtered solar-UV wavelengths produced by a fluorescent sunlamp followed by treatment with photoreactivating light. With a modification of bromodeoxyuridine photolysis assay, it was found that the solar-UV-induced non-dimer DNA damages were repaired by a short-patch repair mechanism in which less than 20 nucleotides were inserted into a repaired region. Similar results were also obtained for γ-irradiated cells. In contrast, excision repair of 254 nm-induced dimers was accomplished by a long-patch process in which an average of about 180 nucleotides were inserted into the repaired sites. A mutant cell line, DRP 36, hypersensitive to non-dimer DNA damages, was isolated from I CR 2A cells. It was found that the DRP 36 cells performed a significantly lower level of excision repair following the induction of non-dimer DNA damages. The results are consistent with the conclusion that the DRP 36 cells are deficient in the repair of at least one type of solar-UV-induced non-dimer DNA lesion. These experiments indicate that solar-UV-induced non-dimer DNA photoproducts behave more like the photoproducts of γ-rays than those of far-UV radiation, which are primarily pyrimidine dimers

  12. Rubidium dimers in paraffin-coated cells

    International Nuclear Information System (INIS)

    Acosta, V M; Windes, D; Corsini, E; Ledbetter, M P; Karaulanov, T; Budker, D; Jarmola, A; Auzinsh, M; Rangwala, S A; Jackson Kimball, D F

    2010-01-01

    Measurements were made to determine the density of rubidium dimer vapor in paraffin-coated cells. The number density of dimers and atoms in similar paraffin-coated and uncoated cells was measured by optical spectroscopy. Due to the relatively low melting point of paraffin, a limited temperature range of 43-80 0 C was explored, with the lower end corresponding to a dimer density of less than 10 7 cm -3 . With 1 min integration time, a sensitivity to dimer number density of better than 10 6 cm -3 was achieved. No significant difference in dimer density between the cells was observed.

  13. Fiber optic D dimer biosensor

    Science.gov (United States)

    Glass, Robert S.; Grant, Sheila A.

    1999-01-01

    A fiber optic sensor for D dimer (a fibrinolytic product) can be used in vivo (e.g., in catheter-based procedures) for the diagnosis and treatment of stroke-related conditions in humans. Stroke is the third leading cause of death in the United States. It has been estimated that strokes and stroke-related disorders cost Americans between $15-30 billion annually. Relatively recently, new medical procedures have been developed for the treatment of stroke. These endovascular procedures rely upon the use of microcatheters. These procedures could be facilitated with this sensor for D dimer integrated with a microcatheter for the diagnosis of clot type, and as an indicator of the effectiveness, or end-point of thrombolytic therapy.

  14. Low-energy elastic electron interactions with pyrimidine

    International Nuclear Information System (INIS)

    Palihawadana, Prasanga; Sullivan, James; Buckman, Stephen; Brunger, Michael; Winstead, Carl; McKoy, Vincent; Garcia, Gustavo; Blanco, F.

    2011-01-01

    We present results of measurements and calculations of elastic electron scattering from pyrimidine in the energy range 3-50 eV. Absolute differential and integral elastic cross sections have been measured using a crossed electron-molecule beam spectrometer and the relative flow technique. The measured cross sections are compared with results of calculations using the well-known Schwinger variational technique and an independent-atom model. Agreement between the measured differential cross sections and the results of the Schwinger calculations is good at lower energies but less satisfactory at higher energies where inelastic channels that should be open are kept closed in the calculations.

  15. Melanin offers protection against induction of cyclobutane pyrimidine dimers and 6-4 photoproducts by UVB in cultured human melanocytes

    NARCIS (Netherlands)

    Smit, N.P.M.; Vink, A.A.; Kolb, R.M.; Steenwinkel, M.J.S.T.; Berg, P.T.M. van den; Nieuwpoort, F. van; Roza, L.; Pavel, S.

    2001-01-01

    The goal of this investigation was to correlate the melanin content in human pigmentary cells with the generation of UVB-induced photoproducts and to examine the relationship between the melanin content and the removal of the photoproducts. Cultured melanocytes from light-skinned individuals

  16. Dissociative attachment to lithium dimers

    International Nuclear Information System (INIS)

    Wadehra, J.M.

    1987-01-01

    The cross sections and the rates of production of negative ions of atomic lithium by the process of dissociative electron attachment to lithium dimers are obtained by using the resonant scattering theory. Both the cross sections as well as the rates of attachment are enhanced if the lithium molecule is initially vibrationally excited. General expressions for approximately obtaining the rates of electron attachment to any vibrational level of Li 2 are presented

  17. Method development and validation of potent pyrimidine derivative by UV-VIS spectrophotometer.

    Science.gov (United States)

    Chaudhary, Anshu; Singh, Anoop; Verma, Prabhakar Kumar

    2014-12-01

    A rapid and sensitive ultraviolet-visible (UV-VIS) spectroscopic method was developed for the estimation of pyrimidine derivative 6-Bromo-3-(6-(2,6-dichlorophenyl)-2-(morpolinomethylamino) pyrimidine4-yl) -2H-chromen-2-one (BT10M) in bulk form. Pyrimidine derivative was monitored at 275 nm with UV detection, and there is no interference of diluents at 275 nm. The method was found to be linear in the range of 50 to 150 μg/ml. The accuracy and precision were determined and validated statistically. The method was validated as a guideline. The results showed that the proposed method is suitable for the accurate, precise, and rapid determination of pyrimidine derivative. Graphical Abstract Method development and validation of potent pyrimidine derivative by UV spectroscopy.

  18. Split warhead simultaneous impact

    Directory of Open Access Journals (Sweden)

    Rahul Singh Dhari

    2017-12-01

    Full Text Available A projectile system is proposed to improve efficiency and effectiveness of damage done by anti-tank weapon system on its target by designing a ballistic projectile that can split into multiple warheads and engage a target at the same time. This idea has been developed in interest of saving time consumed from the process of reloading and additional number of rounds wasted on target during an attack. The proposed system is achieved in three steps: Firstly, a mathematical model is prepared using the basic equations of motion. Second, An Ejection Mechanism of proposed warhead is explained with the help of schematics. Third, a part of numerical simulation which is done using the MATLAB software. The final result shows various ranges and times when split can be effectively achieved. With the new system, impact points are increased and hence it has a better probability of hitting a target.

  19. On split Lie triple systems

    Indian Academy of Sciences (India)

    We also introduced in [1] techniques of connection of roots in the framework of split Lie algebras. In the present paper we extend these techniques to the framework of split Lie triple systems so as to obtain a generalization of the results in [1]. We consider the wide class of split Lie triple systems (which contains the class of.

  20. Cellular pharmacology of fluorinated pyrimidines in vivo in man.

    Science.gov (United States)

    Kovach, J S; Beart, R W

    1989-04-01

    Fluorinated pyrimidines, particularly 5-fluorouracil (FUra), have been the subject of intense and almost continuous basic and clinical study since development in the late 1950's by Dr. Charles Heidelberger. Despite this intensive effort, the most important mechanisms by which FUra influences tumor growth in individual cancer patients and the therapeutically optimum method of administration of the drug alone and in combination with other drugs or ionizing radiation continue to be questions of interest. This article reviews aspects of the study of FUra pertinent to the thesis that for this drug as for other agents used to treat human cancers, data on intracellular concentrations of drug and metabolites as a function of dose, schedule of administration and time are needed for correlation with effects on tumor proliferation if a rational basis for individualization of therapy is to be achieved. A preliminary description of ongoing studies of the tissue concentrations of FUra and metabolites in human colorectal carcinoma and in adjacent normal bowel after rapid injection and after 24-hour infusion of radiolabelled pharmacologically active doses of FUra is included as one approach to learning more about the cellular pharmacology of fluorinated pyrimidines.

  1. Lapachol, a compound targeting pyrimidine metabolism, ameliorates experimental autoimmune arthritis.

    Science.gov (United States)

    Peres, Raphael S; Santos, Gabriela B; Cecilio, Nerry T; Jabor, Valquíria A P; Niehues, Michael; Torres, Bruna G S; Buqui, Gabriela; Silva, Carlos H T P; Costa, Teresa Dalla; Lopes, Norberto P; Nonato, Maria C; Ramalho, Fernando S; Louzada-Júnior, Paulo; Cunha, Thiago M; Cunha, Fernando Q; Emery, Flavio S; Alves-Filho, Jose C

    2017-03-07

    The inhibition of pyrimidine biosynthesis by blocking the dihydroorotate dehydrogenase (DHODH) activity, the prime target of leflunomide (LEF), has been proven to be an effective strategy for rheumatoid arthritis (RA) treatment. However, a considerable proportion of RA patients are refractory to LEF. Here, we investigated lapachol (LAP), a natural naphthoquinone, as a potential DHODH inhibitor and addressed its immunosuppressive properties. Molecular flexible docking studies and bioactivity assays were performed to determine the ability of LAP to interact and inhibit DHODH. In vitro studies were conducted to assess the antiproliferative effect of LAP using isolated lymphocytes. Finally, collagen-induced arthritis (CIA) and antigen-induced arthritis (AIA) models were employed to address the anti-arthritic effects of LAP. We found that LAP is a potent DHODH inhibitor which had a remarkable ability to inhibit both human and murine lymphocyte proliferation in vitro. Importantly, uridine supplementation abrogated the antiproliferative effect of LAP, supporting that the pyrimidine metabolic pathway is the target of LAP. In vivo, LAP treatment markedly reduced CIA and AIA progression as evidenced by the reduction in clinical score, articular tissue damage, and inflammation. Our findings propose a binding model of interaction and support the ability of LAP to inhibit DHODH, decreasing lymphocyte proliferation and attenuating the severity of experimental autoimmune arthritis. Therefore, LAP could be considered as a potential immunosuppressive lead candidate with potential therapeutic implications for RA.

  2. Lie Markov models with purine/pyrimidine symmetry.

    Science.gov (United States)

    Fernández-Sánchez, Jesús; Sumner, Jeremy G; Jarvis, Peter D; Woodhams, Michael D

    2015-03-01

    Continuous-time Markov chains are a standard tool in phylogenetic inference. If homogeneity is assumed, the chain is formulated by specifying time-independent rates of substitutions between states in the chain. In applications, there are usually extra constraints on the rates, depending on the situation. If a model is formulated in this way, it is possible to generalise it and allow for an inhomogeneous process, with time-dependent rates satisfying the same constraints. It is then useful to require that, under some time restrictions, there exists a homogeneous average of this inhomogeneous process within the same model. This leads to the definition of "Lie Markov models" which, as we will show, are precisely the class of models where such an average exists. These models form Lie algebras and hence concepts from Lie group theory are central to their derivation. In this paper, we concentrate on applications to phylogenetics and nucleotide evolution, and derive the complete hierarchy of Lie Markov models that respect the grouping of nucleotides into purines and pyrimidines-that is, models with purine/pyrimidine symmetry. We also discuss how to handle the subtleties of applying Lie group methods, most naturally defined over the complex field, to the stochastic case of a Markov process, where parameter values are restricted to be real and positive. In particular, we explore the geometric embedding of the cone of stochastic rate matrices within the ambient space of the associated complex Lie algebra.

  3. Novel covalently linked insulin dimer engineered to investigate the function of insulin dimerization

    DEFF Research Database (Denmark)

    Vinther, Tine N.; Norrman, Mathias; Strauss, Holger M.

    2012-01-01

    An ingenious system evolved to facilitate insulin binding to the insulin receptor as a monomer and at the same time ensure sufficient stability of insulin during storage. Insulin dimer is the cornerstone of this system. Insulin dimer is relatively weak, which ensures dissociation into monomers...... and insulin stability and function, we engineered a covalently linked insulin dimer in which two monomers were linked by a disulfide bond. The structure of this covalent dimer was identical to the self-association dimer of human insulin. Importantly, this covalent dimer was capable of further oligomerization...

  4. Solitary waves in dimer binary collision model

    Science.gov (United States)

    Ahsan, Zaid; Jayaprakash, K. R.

    2017-01-01

    Solitary wave propagation in nonlinear diatomic (dimer) chains is a very interesting topic of research in the study of nonlinear lattices. Such waves were recently found to be supported by the essentially nonlinear granular lattice and Toda lattice. An interesting aspect of this discovery is attributed to the realization of a spectrum of the mass ratio (the only system parameter governing the dynamics) that supports the propagation of such waves corresponding to the considered interaction potential. The objective of this exposition is to explore solitary wave propagation in the dimer binary collision (BC) model. Interestingly, the dimer BC model supports solitary wave propagation at a discrete spectrum of mass ratios similar to those observed in granular and Toda dimers. Further, we report a qualitative and one-to-one correspondence between the spectrum of the mass ratio corresponding to the dimer BC model and those corresponding to granular and Toda dimer chains.

  5. Absorption and intermediary metabolism of purines and pyrimidines in lactating dairy cows.

    Science.gov (United States)

    Stentoft, Charlotte; Røjen, Betina Amdisen; Jensen, Søren Krogh; Kristensen, Niels B; Vestergaard, Mogens; Larsen, Mogens

    2015-02-28

    About 20 % of ruminal microbial N in dairy cows derives from purines and pyrimidines; however, their intermediary metabolism and contribution to the overall N metabolism has sparsely been described. In the present study, the postprandial patterns of net portal-drained viscera (PDV) and hepatic metabolism were assessed to evaluate purine and pyrimidine N in dairy cows. Blood was sampled simultaneously from four veins with eight hourly samples from four multi-catheterised Holstein cows. Quantification of twenty purines and pyrimidines was performed with HPLC-MS/MS, and net fluxes were estimated across the PDV, hepatic tissue and total splanchnic tissue (TSP). Concentration differences between veins of fifteen purine and pyrimidine nucleosides (NS), bases (BS) and degradation products (DP) were different from zero (P≤ 0·05), resulting in the net PDV releases of purine NS (0·33-1·3 mmol/h), purine BS (0·0023-0·018 mmol/h), purine DP (7·0-7·8 mmol/h), pyrimidine NS (0·30-2·8 mmol/h) and pyrimidine DP (0·047-0·77 mmol/h). The hepatic removal of purine and pyrimidine was almost equivalent to the net PDV release, resulting in no net TSP release. One exception was uric acid (7·9 mmol/h) from which a large net TSP release originated from the degradation of purine NS and BS. A small net TSP release of the pyrimidine DP β-alanine and β-aminoisobutyric acid (-0·032 to 0·37 mmol/h) demonstrated an outlet of N into the circulating N pool. No effect of time relative to feeding was observed (P>0·05). These data indicate that considerable amounts of N are lost in the dairy cow due to prominent intermediary degradation of purines, but that pyrimidine N is reusable to a larger extent.

  6. An Efficient, Clean, and Catalyst-Free Synthesis of Fused Pyrimidines Using Sonochemistry

    Directory of Open Access Journals (Sweden)

    M. Mamaghani

    2014-01-01

    Full Text Available In this report, synthesis of indenopyrido[2,3-d]pyrimidine and pyrimido[4,5-b]quinoline derivatives was investigated via one-pot three-component reaction between 6-amino-2-(alkylthio-pyrimidin-4(3Hone, 1,3-indanedione, or 1,3-cyclohexadione and arylaldehyde under ultrasonic irradiation in ethylene glycol as solvent at 65°C. In these reactions fused pyrimidine derivatives were synthesized with high to excellent yields (82–97% and short reaction times (10–33 min.

  7. Strains of Lactococcus lactis with a partial pyrimidine requirement show sensitivity toward aspartic acid

    DEFF Research Database (Denmark)

    Wadskov-Hansen, Steen Lyders Lerche; Martinussen, Jan

    2009-01-01

    The growth rate of the widely used laboratory strain Lactococcus lactis subsp. cremoris LM0230 was reduced if aspartic acid were present in the growth medium. The strain LM0230 is a plasmid- and phage-cured derivative of L. lactis subsp. cremoris C2, the ancestor of the original dairy isolate L...... that the partial pyrimidine requirement can be explained by a low specific activity of the pyrimidine biosynthetic enzymes. In conclusion, L. lactis LM0230 during the process of plasmid- and prophage-curing has acquired a partial pyrimidine requirement resulting in sensitivity toward aspartic acid....

  8. Regulation of Salmonella typhimurium pyr Gene Expression: Effect of Changing Both Purine and Pyrimidine Nucleotide Pools

    DEFF Research Database (Denmark)

    Jensen, Kaj Frank

    1989-01-01

    The synthesis of the pyrimidine biosynthetic enzymes is repressed by the pyrimidine nucleotide end-products of the pathway. However, purine nucleotides also play a role. In this study, I have measured expression of the pyr genes (pyrA-E) in Salmonella typhimurium strains harbouring mutations...... that permit manipulation of the intracellular pools of both pyrimidine and purine nucleotides. The results identify the effectory purine compound as being a guanine nucleotide; it is probably GTP, but it may be GDP or GMP. The synthesis of carbamoylphosphate synthase, encoded by pyrA, and particularly...

  9. The use of pyr-mutations to modify pyrimidine pools in Lactococci

    DEFF Research Database (Denmark)

    Hansen, Steen Lyders Lerche; Martinussen, Jan; Hammer, Karin

    1999-01-01

    . If pyrimidines are only available through salvage of uracil and/or cytidine, the pools of CTP and UTP can be varied independently by controlling the activities of cytidine-deaminase (cdd) and CTP-synthetase (pyrG). Cytidine-deaminase catalyses the deamination of cytidine leading to uridine and CTP....... By combining the two described mutations, with a cdd mutation, we will be able to construct strains in which pyrimidine pools can be manipulated by adding different pyrimidine-sources at variable concentrations to the growth media. Since nucleotides are central metabolites, many physiological parameters may...

  10. The use of Pyr-mutants to modify pyrimidine metabolism in lactococci

    DEFF Research Database (Denmark)

    Hansen, Steen Lyders Lerche; Martinussen, Jan; Hammer, Karin

    1998-01-01

    . If pyrimidines are only available through salvage of uracil and/or cytidine, the pools of CTP and UTP can be varied independently by controlling the activities of cytidine-deaminase (cdd) and CTP-synthetase (pyrG). Cytidine-deaminase catalyses the deamination of cytidine leading to uridine and CTP....... By combining the two described mutations, with a cdd mutation, we will be able to construct strains in which pyrimidine pools can be manipulated by adding different pyrimidine-sources at variable concentrations to the growth media. Since nucleotides are central metabolites, many physiological parameters may...

  11. Haplopappus gracilis cell strains resistant to pyrimidine analogues.

    Science.gov (United States)

    Jones, G E; Hann, J

    1979-03-01

    Strains of Haplopappus gracilis (Nutt.) Gray cells resistant to 6-azauracil have been isolated from cultures of diploid cells. These strains are also resistant to 8-azaguanine, as is their parent. The variants are 100- to 125-fold more resistant to 6-azauracil than their parent, and they exhibit different spectra of cross resistance to other pyrimidine analogues. The phenotype of each variant is stable in the absence of selection. The majority of cells in cultures of the variants are diploid; all others examined were tetraploid. Initial rates of uptake of uracil are not reduced in the variants. Fluorouracil, to which two variants are resistant, is taken up by one of them as well as by the parent. Responses of the other two to fluorouracil are not correlated with decreased ability to accumulate this analogue.

  12. Enzymatic oxidative dimerization of silymarin flavonolignans

    Czech Academy of Sciences Publication Activity Database

    Gavezzotti, P.; Vavříková, Eva; Valentová, Kateřina; Fronza, G.; Kudanga, T.; Kuzma, Marek; Riva, S.; Biedermann, David; Křen, Vladimír

    2014-01-01

    Roč. 109, NOV 2014 (2014), s. 24-30 ISSN 1381-1177 R&D Projects: GA MŠk(CZ) LD13041; GA ČR(CZ) GP14-14373P Institutional support: RVO:61388971 Keywords : Silybin dimers * Silydianin dimer * Silymarin Subject RIV: CE - Biochemistry Impact factor: 2.128, year: 2014

  13. Absorption and Intermediary Metabolism of Purines and Pyrimidines in Lactating Dairy Cows

    DEFF Research Database (Denmark)

    Nielsen, Charlotte Stentoft; Røjen, Betina Amdisen; Jensen, Søren Krogh

    2015-01-01

    /h), purine BS (0·0023–0·018 mmol/h), purine DP (7·0–7·8 mmol/h), pyrimidine NS (0·30–2·8 mmol/h) and pyrimidine DP (0·047–0·77 mmol/h). The hepatic removal of purine and pyrimidine was almost equivalent to the net PDV release, resulting in no net TSP release. One exception was uric acid (7·9 mmol/h) from...... which a large net TSP release originated from the degradation of purine NS and BS. A small net TSP release of the pyrimidine DP β-alanine and β-aminoisobutyric acid ( − 0·032 to 0·37 mmol/h) demonstrated an outlet of N into the circulating N pool. No effect of time relative to feeding was observed (P>0...

  14. Synthesis and evaluation of chalcone analogues based pyrimidines as angiotensin converting enzyme inhibitors.

    Science.gov (United States)

    Bukhari, S N A; Butt, A M; Amjad, M W B; Ahmad, W; Shah, V H; Trivedi, A R

    2013-11-01

    Hypertension is a widespread and frequently progressive ailment that imparts a foremost threat for cardiovascular and renal disorders. Mammoth efforts are needed for the synthesis of innovative antihypertensive agents to combat this lethal disease. Chalcones have shown antihypertensive activity through inhibition of Angiotensin Converting Enzyme (ACE). Hence, a series of chalcone analogues is synthesized and used as precursor for the synthesis of novel series of pyrimidines. Precursor chalcones were prepared by reacting aldehydes and ketones in presence of sodium hydroxide followed by synthesis of corresponding pyrimidines by reaction with urea in presence of potassium hydroxide. Both groups were then evaluated for their effects on ACE. The results depicted that pyrimidines were more active than chalcones with methoxy (C5 and P5) substitution showing best results to inhibit ACE. Given that chalcone analogues and pyrimidines show a potential as the angiotensin converting enzyme inhibitors.

  15. Directed diffusion of reconstituting dimers

    Energy Technology Data Exchange (ETDEWEB)

    Barma, Mustansir [Department of Theoretical Physics, Tata Institute of Fundamental Research, Mumbai 400005 (India); Grynberg, Marcelo D [Departamento de Fisica, Universidad Nacional de La Plata (1900) La Plata (Argentina); Stinchcombe, Robin B [Isaac Newton Institute for Mathematical Sciences, 20 Clarkson Road, Cambridge CB3 0EH (United Kingdom)

    2007-02-14

    We discuss the dynamical aspects of an asymmetric version of assisted diffusion of hard core particles on a ring studied by Menon et al (1997 J. Stat. Phys. 86 1237). The asymmetry brings in phenomena like kinematic waves and effects of the Kardar-Parisi-Zhang non-linearity, which combine with the feature of strongly broken ergodicity, a characteristic of the model. A central role is played by a single non-local invariant, the irreducible string, whose interplay with the driven motion of reconstituting dimers, arising from the assisted hopping, determines the asymptotic dynamics and scaling regimes. These are investigated both analytically and numerically through sector-dependent mappings to the asymmetric simple exclusion process.

  16. A single-molecular twin rotor: correlated motion of two pyrimidine rings coordinated to copper.

    Science.gov (United States)

    Takara, Yusuke; Kusamoto, Tetsuro; Masui, Tatsuya; Nishikawa, Michihiro; Kume, Shoko; Nishihara, Hiroshi

    2015-02-18

    We describe the two correlated rotational motions of pyrimidine rings in 4,4'-dimethyl-2,2'-bipyrimidine ligated to Cu(i). The two pyrimidine rings delimited by anthryl and phenanthroline groups rotate to afford three isomers. (1)H NMR measurements revealed that the two rotational processes were activated at different temperatures. Cyclic voltammetry gave the kinetic and thermodynamic parameters that provide clear evidence of the correlation between the two rotational steps.

  17. Inhibitory effect of novel pyrimidines on ATP and ADP hydrolysis in synaptosomes from rat cerebral cortex.

    Science.gov (United States)

    Cechin, Sirlene R; Schetinger, Maria Rosa C; Zanatta, Nilo; Madruga, Claudia C; Pacholski, Iraci L; Flores, Darlene C; Bonacorso, Helio G; Martins, Marcos A P; Morsch, Vera M

    2003-11-01

    In this study, a new series of trihalomethyl-substituted pyrimidines and dihydropyrimidines were synthesized and tested as potential NTPDase inhibitors. For this purpose, synaptosomes from rat cerebral cortex were used as the enzyme source and ATP and ADP were used as the substrate. Among the new compounds, 4-methyl-2-methylsulfanyl-6-trichloromethylpyrimidine (2b) was found to be the most effective noncompetitive inhibitor, with an estimated K(i) value of 0.18 and 0.55 mM for ATP and ADP, respectively. Other pyrimidines inhibited NTPDase activity with the following rank order of inhibitory potency: 3,6-dimethyl-2-methylsulfanyl-4-trifluoromethyl-3,4-dihydro-pyrimidin-4-ol (3a) > 5-methyl-2-(4-methyl-6-trifluoromethyl-pyrimidin-2-yl)-3-trifluoromethyl-3,4-dihydro-2H-3-pyrazol-3-ol (6a) > 5-bromo-4,6-dimethoxy-4-trichloromethyl-1,2,3,4-tetrahydro-2-pyrimidin-2-one (9) for ATP and 6a > 9 > 3a for ADP. Our results demonstrate that a novel group of pyrimidines compounds can act as inhibitors of ATP and ADP hydrolysis in synaptosomes from rat cerebral cortex. These results can contribute for the understanding of the NTPDase activity and for further studies involving new compounds that can enlist as it inhibitors.

  18. Biotransformation and Cytotoxic Activity of Guaiacol Dimer

    Directory of Open Access Journals (Sweden)

    Galuh Widiyarti

    2014-07-01

    Full Text Available Guaiacol, a phenolic compound is known as an anticancer. Dimerization of guaiacol has been done by biotransformation using peroxidase enzyme as biocatalyst. This enzyme was isolated from Indonesian plant, kailan (Brassica oleraceae var. alboglabra. Analysis of dimerization product was carried out by TLC, IR, LC-MS, and NMR. Whilst analysis of in-vitro cytotoxic activity was carried out by MTT method against breast cancer T47D and MCF7 cells. The result showed that the dimerization reaction gave O-para dehydroguaiacol. The in-vitro cytotoxic activity analysis showed that O-para dehydroguaiacol compound has potency as anti-breast cancer.

  19. Split SUSY Radiates Flavor

    CERN Document Server

    Baumgart, Matthew; Zorawski, Thomas

    2014-01-01

    Radiative flavor models where the hierarchies of Standard Model (SM) fermion masses and mixings are explained via loop corrections are elegant ways to solve the SM flavor puzzle. Here we build such a model in the context of Mini-Split Supersymmetry (SUSY) where both flavor and SUSY breaking occur at a scale of 1000 TeV. This model is consistent with the observed Higgs mass, unification, and WIMP dark matter. The high scale allows large flavor mixing among the sfermions, which provides part of the mechanism for radiative flavor generation. In the deep UV, all flavors are treated democratically, but at the SUSY breaking scale, the third, second, and first generation Yukawa couplings are generated at tree level, one loop, and two loops, respectively. Save for one, all the dimensionless parameters in the theory are O(1), with the exception being a modest and technically natural tuning that explains both the smallness of the bottom Yukawa coupling and the largeness of the Cabibbo angle.

  20. How rivers split

    Science.gov (United States)

    Seybold, H. F.; Yi, R.; Devauchelle, O.; Petroff, A.; Rothman, D.

    2012-12-01

    River networks have fascinated mankind for centuries. They exhibit a striking geometry with similar shapes repeating on all scales. Yet, how these networks form and create these geometries remains elusive. Recently we have shown that channels fed by subsurface flow split at a characteristic angle of 2π/5 unambiguously consistent with our field measurements in a seepage network on the Florida Panhandle (Fig.1). Our theory is based only on the simple hypothesis that the channels grow in the direction at which the ground water enters the spring and classical solutions of subsurface hydrology. Here we apply our analysis to the ramification of large drainage basins and extend our theory to include slope effects. Using high resolution stream networks from the National Hydrography Dataset (NHD), we scrutinize our hypothesis in arbitrary channel networks and investigate the branching angle dependence on Horton-Strahler order and the maturity of the streams.; High-resolution topographic map of valley networks incised by groundwater flow, located on the Florida Panhandle near Bristol, FL.

  1. Split supersymmetry radiates flavor

    Science.gov (United States)

    Baumgart, Matthew; Stolarski, Daniel; Zorawski, Thomas

    2014-09-01

    Radiative flavor models where the hierarchies of Standard Model (SM) fermion masses and mixings are explained via loop corrections are elegant ways to solve the SM flavor puzzle. Here we build such a model in the context of mini-split supersymmetry (SUSY) where both flavor and SUSY breaking occur at a scale of 1000 TeV. This model is consistent with the observed Higgs mass, unification, and dark matter as a weakly interacting massive particle. The high scale allows large flavor mixing among the sfermions, which provides part of the mechanism for radiative flavor generation. In the deep UV, all flavors are treated democratically, but at the SUSY-breaking scale, the third, second, and first generation Yukawa couplings are generated at tree level, one loop, and two loops, respectively. Save for one, all the dimensionless parameters in the theory are O(1), with the exception being a modest and technically natural tuning that explains both the smallness of the bottom Yukawa coupling and the largeness of the Cabibbo angle.

  2. Effect of Surface Plasmon Coupling to Optical Cavity Modes on the Field Enhancement and Spectral Response of Dimer-Based sensors

    KAUST Repository

    Alrasheed, Salma

    2017-09-05

    We present a theoretical approach to narrow the plasmon linewidth and enhance the near-field intensity at a plasmonic dimer gap (hot spot) through coupling the electric localized surface plasmon (LSP) resonance of a silver hemispherical dimer with the resonant modes of a Fabry-Perot (FP) cavity. The strong coupling is demonstrated by the large anticrossing in the reflection spectra and a Rabi splitting of 76 meV. Up to 2-fold enhancement increase can be achieved compared to that without using the cavity. Such high field enhancement has potential applications in optics, including sensors and high resolution imaging devices. In addition, the resonance splitting allows for greater flexibility in using the same array at different wavelengths. We then further propose a practical design to realize such a device and include dimers of different shapes and materials.

  3. Fenarimol, a Pyrimidine-Type Fungicide, Inhibits Brassinosteroid Biosynthesis

    Directory of Open Access Journals (Sweden)

    Keimei Oh

    2015-07-01

    Full Text Available The plant steroid hormone brassinosteroids (BRs are important signal mediators that regulate broad aspects of plant growth and development. With the discovery of brassinoazole (Brz, the first specific inhibitor of BR biosynthesis, several triazole-type BR biosynthesis inhibitors have been developed. In this article, we report that fenarimol (FM, a pyrimidine-type fungicide, exhibits potent inhibitory activity against BR biosynthesis. FM induces dwarfism and the open cotyledon phenotype of Arabidopsis seedlings in the dark. The IC50 value for FM to inhibit stem elongation of Arabidopsis seedlings grown in the dark was approximately 1.8 ± 0.2 μM. FM-induced dwarfism of Arabidopsis seedlings could be restored by brassinolide (BL but not by gibberellin (GA. Assessment of the target site of FM in BR biosynthesis by feeding BR biosynthesis intermediates indicated that FM interferes with the side chain hydroxylation of BR biosynthesis from campestanol to teasterone. Determination of the binding affinity of FM to purified recombinant CYP90D1 indicated that FM induced a typical type II binding spectrum with a Kd value of approximately 0.79 μM. Quantitative real-time PCR analysis of the expression level of the BR responsive gene in Arabidopsis seedlings indicated that FM induces the BR deficiency in Arabidopsis.

  4. Discovery of Macrocyclic Pyrimidines as MerTK-Specific Inhibitors.

    Science.gov (United States)

    McIver, Andrew L; Zhang, Weihe; Liu, Qingyang; Jiang, Xinpeng; Stashko, Michael A; Nichols, James; Miley, Michael J; Norris-Drouin, Jacqueline; Machius, Mischa; DeRyckere, Deborah; Wood, Edgar; Graham, Douglas K; Earp, H Shelton; Kireev, Dmitri; Frye, Stephen V; Wang, Xiaodong

    2017-02-03

    Macrocycles have attracted significant attention in drug discovery recently. In fact, a few de novo designed macrocyclic kinase inhibitors are currently in clinical trials with good potency and selectivity for their intended target. In this study, we successfully engaged a structure-based drug design approach to discover macrocyclic pyrimidines as potent Mer tyrosine kinase (MerTK)-specific inhibitors. An enzyme-linked immunosorbent assay (ELISA) in 384-well format was employed to evaluate the inhibitory activity of macrocycles in a cell-based assay assessing tyrosine phosphorylation of MerTK. Through structure-activity relationship (SAR) studies, analogue 11 [UNC2541; (S)-7-amino-N-(4-fluorobenzyl)-8-oxo-2,9,16-triaza-1(2,4)-pyrimidinacyclohexadecaphane-1-carboxamide] was identified as a potent and MerTK-specific inhibitor that exhibits sub-micromolar inhibitory activity in the cell-based ELISA. In addition, an X-ray structure of MerTK protein in complex with 11 was resolved to show that these macrocycles bind in the MerTK ATP pocket. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  5. Photochemistry of Pyrimidine in Astrophysical Ices: Formation of Nucleobases and Other Prebiotic Species

    Science.gov (United States)

    Nuevo, Michel; Sandford, Scott A.; Materese, Christopher K.; Milam, Stefanie N.

    2012-01-01

    Nucleobases are N-heterocycles that are the informational subunits of DNA and RNA. They are divided into two molecular groups: pyrimidine bases (uracil, cytosine, and thymine) and purine bases (adenine and guanine). Nucleobases have been detected in meteorites, and their extraterrestrial origin confirmed by isotopic measurements. Although no N-heterocycles have ever been observed in the ISM, the positions of the 6.2- m interstellar emission features suggest a population of such molecules is likely to be present. However, laboratory experiments have shown that the ultraviolet (UV) irradiation of pyrimidine in ices of astrophysical relevance such as H2O, NH3, CH3OH, CH4, CO, or combinations of these at low temperature (less than or equal to 20 K) leads to the formation of several pyrimidine derivatives including the nucleobases uracil and cytosine, as well as precursors such as 4(3H)-pyrimidone and 4-aminopyrimidine. Quantum calculations on the formation of 4(3H)-pyrimidone and uracil from the irradiation of pyrimidine in pure H2O ices are in agreement with their experimental formation pathways.10 In those residues, other species of prebiotic interest such as urea as well as the amino acids glycine and alanine could also be identified. However, only very small amounts of pyrimidine derivatives containing CH3 groups could be detected, suggesting that the addition of methyl groups to pyrimidine is not an efficient process. For this reason, the nucleobase thymine was not observed in any of the samples. In this work, we study the formation of nucleobases and other photo-products of prebiotic interest from the UV irradiation of pyrimidine in ices containing H2O, NH3, CH3OH, and CO, mixed in astrophysical proportions.

  6. Global Locator, Local Locator, and Identifier Split (GLI-Split

    Directory of Open Access Journals (Sweden)

    Michael Menth

    2013-03-01

    Full Text Available The locator/identifier split is an approach for a new addressing and routing architecture to make routing in the core of the Internet more scalable. Based on this principle, we developed the GLI-Split framework, which separates the functionality of current IP addresses into a stable identifier and two independent locators, one for routing in the Internet core and one for edge networks. This makes routing in the Internet more stable and provides more flexibility for edge networks. GLI-Split can be incrementally deployed and it is backward-compatible with the IPv6 Internet. We describe its architecture, compare it to other approaches, present its benefits, and finally present a proof-of-concept implementation of GLI-Split.

  7. Synthesis of new dimeric carvacrol compounds

    Directory of Open Access Journals (Sweden)

    Uttam B. More

    2008-12-01

    Full Text Available The polymer supported carvacrol anion was reacted with 1,2-dibromoethane, 1,4-dibromoethane, oxalyl dichloride, malonyl dichloride, succinyl dichloride, glutaroyl dichloride, and adipoyl dichloride to afford the corresponding dimeric carvacryl ethers or esters

  8. Split-illumination electron holography

    International Nuclear Information System (INIS)

    Tanigaki, Toshiaki; Aizawa, Shinji; Suzuki, Takahiro; Park, Hyun Soon; Inada, Yoshikatsu; Matsuda, Tsuyoshi; Taniyama, Akira; Shindo, Daisuke; Tonomura, Akira

    2012-01-01

    We developed a split-illumination electron holography that uses an electron biprism in the illuminating system and two biprisms (applicable to one biprism) in the imaging system, enabling holographic interference micrographs of regions far from the sample edge to be obtained. Using a condenser biprism, we split an electron wave into two coherent electron waves: one wave is to illuminate an observation area far from the sample edge in the sample plane and the other wave to pass through a vacuum space outside the sample. The split-illumination holography has the potential to greatly expand the breadth of applications of electron holography.

  9. The two-state dimer receptor model: a general model for receptor dimers.

    Science.gov (United States)

    Franco, Rafael; Casadó, Vicent; Mallol, Josefa; Ferrada, Carla; Ferré, Sergi; Fuxe, Kjell; Cortés, Antoni; Ciruela, Francisco; Lluis, Carmen; Canela, Enric I

    2006-06-01

    Nonlinear Scatchard plots are often found for agonist binding to G-protein-coupled receptors. Because there is clear evidence of receptor dimerization, these nonlinear Scatchard plots can reflect cooperativity on agonist binding to the two binding sites in the dimer. According to this, the "two-state dimer receptor model" has been recently derived. In this article, the performance of the model has been analyzed in fitting data of agonist binding to A(1) adenosine receptors, which are an example of receptor displaying concave downward Scatchard plots. Analysis of agonist/antagonist competition data for dopamine D(1) receptors using the two-state dimer receptor model has also been performed. Although fitting to the two-state dimer receptor model was similar to the fitting to the "two-independent-site receptor model", the former is simpler, and a discrimination test selects the two-state dimer receptor model as the best. This model was also very robust in fitting data of estrogen binding to the estrogen receptor, for which Scatchard plots are concave upward. On the one hand, the model would predict the already demonstrated existence of estrogen receptor dimers. On the other hand, the model would predict that concave upward Scatchard plots reflect positive cooperativity, which can be neither predicted nor explained by assuming the existence of two different affinity states. In summary, the two-state dimer receptor model is good for fitting data of binding to dimeric receptors displaying either linear, concave upward, or concave downward Scatchard plots.

  10. Adsorption of dimeric surfactants in lamellar silicates

    Energy Technology Data Exchange (ETDEWEB)

    Balcerzak, Mateusz; Pietralik, Zuzanna [Department of Macromolecular Physics, Faculty of Physics, A. Mickiewicz University, Umultowska 85, 61-614 Poznań (Poland); Domka, Ludwik [Department of Metalorganic Chemistry, Faculty of Chemistry, A. Mickiewicz University, Grunwaldzka 6, 60-780 Poznań (Poland); Skrzypczak, Andrzej [Institute of Chemical Technology, Poznań University of Technology, Berdychowo 4, 60-965 Poznań (Poland); Kozak, Maciej, E-mail: mkozak@amu.edu.pl [Department of Macromolecular Physics, Faculty of Physics, A. Mickiewicz University, Umultowska 85, 61-614 Poznań (Poland)

    2015-12-01

    Highlights: • The intercalation of dimeric surfactants changed the morphology of MMT samples. • XRD indicated structures formed by surfactant molecules in interlayer space. • The four-step thermal decomposition of dimeric surfactant, confirms intercalation. - Abstract: The adsorption of different types of cationic surfactants in lamellar silicates changes their surface character from hydrophilic to hydrophobic. This study was undertaken to obtain lamellar silicates modified by a series of novel dimeric (gemini) surfactants of different length alkyl chains and to characterise these organophilised materials. Synthetic sodium montmorillonite SOMASIF® ME 100 (M) and enriched bentonite of natural origin (Nanoclay – hydrophilic bentonite®) were organophilised with dimeric (gemini) surfactants (1,1′-(1,4-butanediyl)bis(alkoxymethyl)imidazolium dichlorides). As a result of surfactant molecule adsorption in interlamellar space, the d-spacing (d{sub 001}) increased from 0.97 nm (for the anhydrous structure) to 2.04 nm. A Fourier transform infrared spectroscopy (FTIR) analysis of the modified systems reveals bands assigned to the stretching vibrations of the CH{sub 2} and CH{sub 3} groups and the scissoring vibrations of the NH group from the structure of the dimeric surfactants. Thermogravimetric (TG) and derivative thermogravimetric (DTG) studies imply a four-stage process of surfactant decomposition. Scanning electron microscopy (SEM) images provide information on the influence of dimeric surfactant intercalation into the silicate structures. Particles of the modified systems show a tendency toward the formation of irregularly shaped agglomerates.

  11. Retroviral RNA Dimerization: From Structure to Functions

    Directory of Open Access Journals (Sweden)

    Noé Dubois

    2018-03-01

    Full Text Available The genome of the retroviruses is a dimer composed by two homologous copies of genomic RNA (gRNA molecules of positive polarity. The dimerization process allows two gRNA molecules to be non-covalently linked together through intermolecular base-pairing. This step is critical for the viral life cycle and is highly conserved among retroviruses with the exception of spumaretroviruses. Furthermore, packaging of two gRNA copies into viral particles presents an important evolutionary advantage for immune system evasion and drug resistance. Recent studies reported RNA switches models regulating not only gRNA dimerization, but also translation and packaging, and a spatio-temporal characterization of viral gRNA dimerization within cells are now at hand. This review summarizes our current understanding on the structural features of the dimerization signals for a variety of retroviruses (HIVs, MLV, RSV, BLV, MMTV, MPMV…, the mechanisms of RNA dimer formation and functional implications in the retroviral cycle.

  12. ISR split-field magnet

    CERN Multimedia

    CERN PhotoLab

    1975-01-01

    The experimental apparatus used at intersection 4 around the Split-Field Magnet by the CERN-Bologna Collaboration (experiment R406). The plastic scintillator telescopes are used for precise pulse-height and time-of-flight measurements.

  13. Ultraviolet Irradiation of Pyrimidine in Interstellar Ice Analogs: Formation and Photo-Stability of Nucleobases

    Science.gov (United States)

    Nuevo, Michel; Milam, Stefanie N.; Sandford, Scott A.; Elsila, Jamie E.; Dworkin, Jason P.

    2010-01-01

    Astrochemistry laboratory experiments recently showed that molecules of prebiotic interest can potentially form in space, as supported by the detection of amino acids in organic residues formed by the UV photolysis of ices simulating interstellar and cometary environments (H2O, CO, CO2, CH3OH, NH3, etc.). Although the presence of amino acids in the interstellar medium (ISM) is still under debate, experiments and the detection of amino acids in meteorites both support a scenario in which prebiotic molecules could be of extraterrestrial origin, before they are delivered to planets by comets, asteroids, and interplanetary dust particles. Nucleobases, the informational subunits of DNA and RNA, have also been detected in meteorites, although they have not yet been observed in the ISM. Thus, these molecules constitute another family of prebiotic compounds that can possibly form via abiotical processes in astrophysical environments. Nucleobases are nitrogen-bearing cyclic aromatic species with various functional groups attached, which are divided into two classes: pyrimidines (uracil, cytosine, and thymine) and purines (adenine and guanine). In this work, we study how UV irradiation affects pyrimidine mixed in interstellar ice analogs (H2O, NH3, CH3OH). In particular, we show that the UV irradiation of H2O:pyrimidine mixtures leads to the production of oxidized compounds including uracil, and show that both uracil and cytosine are formed upon irradiation of H2O:NH3:pyrimidine mixtures. We also study the photostability of pyrimidine and its photoproducts formed during these experiments.

  14. Synthesis, crystal structure, characterization and antifungal activity of pyrazolo[1,5-a]pyrimidines derivatives

    Science.gov (United States)

    Zhang, Jin; Peng, Ju-Fang; Wang, Tao; Wang, Ping; Zhang, Zun-Ting

    2016-09-01

    Under microwave radiation, isomers 2-(pyrazolo[1,5-a]pyrimidin-5-yl)phenols (3) and 2-(pyrazolo[1,5-a]pyrimidin-7-yl)phenols (4) were simultaneously obtained by the condensation of chromones and 3-aminopyrazoles. These two isomers were fully characterized by IR, 1H NMR, 13C NMR and HRMS. In addition, a representative product 5-chloro-2-(2-methyl-pyrazolo[1,5-a] pyrimidin-5-yl)phenol (3e) was further conformed by the single crystal X-ray diffraction. The antifungal abilities of the obtained products 3 and 4 were evaluated against five phytopathogenic fungi (Cytospora sp., Colletotrichum gloeosporioides, Botrytis cinerea, Alternaria solani and Fusarium solani). The results revealed that 2-(pyrazolo[1,5-a]pyrimidin-5-yl)phenol (3a) and 4-chloro-2-(2-methylpyrazolo[1,5-a]pyrimidin-7-yl)phenol (4e) exhibited good antifungal abilities against Colletotrichum gloeosporioides with the IC50 values of 24.90 and 28.28 μg/mL, respectively.

  15. Synthesis and Antimicrobial Studies of Pyrimidine Pyrazole Heterocycles

    Directory of Open Access Journals (Sweden)

    Rakesh Kumar

    2014-01-01

    Full Text Available Prompted from the diversity of the wider use and being an integral part of genetic material, an effort was made to synthesize pyrimidine pyrazole derivatives of pharmaceutical interest by oxidative cyclization of chalcones with satisfactory yield and purity. A novel series of 1,3-dimethyl-6-hydroxy-2,4-dioxo-5-(1′-phenyl-3′-aryl-1H-pyrazol-5′-yl-1,2,3,4-tetrahydropyrimidines (5a–d and 1,3-diaryl-6-hydroxy-4-oxo-2-thioxo-5-(1′-phenyl-3′-aryl-1H-pyrazol-5′-yl-1,2,3,4-tetrahydropyrimidines (5e–l has been synthesized. The structures of these compounds were established on the basis of FT-IR, 1H NMR, 13C NMR, and mass spectral analysis. All the synthesized compounds were screened for their antimicrobial activity against bacteria and fungi. Among all the compounds, 5g was found to be the most active as its MIC was 31.25 µg/mL against S. aureus and B. cereus. The compounds 5h, 5c, and 5e also possess antibacterial activity with MIC values as 62.50, 125.00, and 500.00 µg/mL, respectively. The compounds 5c and 5j were found to have antifungal activity against Aspergillus spp. As antifungal drugs lag behind the antibacterial drugs, therefore we tried in vitro combination of these two compounds with standard antifungal drugs (polyene and azole against Aspergillus spp. The combination of ketoconazole with 5c and 5j showed synergy at 1 : 8 (6.25 : 50.00 µg/mL and 1 : 4 (25 : 100 µg/mL against A. fumigatus (ITCC 4517 and A. fumigatus (VPCI 190/96, respectively.

  16. D-dimers (DD) in CVST.

    Science.gov (United States)

    Wang, Hui Fang; Pu, Chuan Qiang; Yin, Xi; Tian, Cheng Lin; Chen, Ting; Guo, Jun Hong; Shi, Qiang

    2017-06-01

    We were interested in further confirming whether D-dimers (DD) are indeed elevated in cerebral venous sinus thrombosis (CVST) as reported in those studies. CVST patients who had a plasma D-dimer test (139 cases) were included and divided into two groups: elevated D-dimer group (EDG) (>0.5 μg/mL; 65 cases) and normal D-dimer group (NDG) (≤0.5 μg/mL; 74 cases). The two groups were compared in terms of demographic data, clinical manifestation, laboratory and imaging data, using inferential statistical methods. The chi-squared and Fisher exact test showed that, compared to the NDG (74 cases), patients with elevated D-dimer levels were more likely to have a shorter symptom duration (SD) (30 ± 83.9 versus 90 ± 58.9 d, p = 0.003), more risk factors (75.4% versus 52.7%, p = 0.006), higher multiple venous sinus involvement (75.4% versus 59.5%, p = 0.037), increased fibrinogen (43.1% versus 18.9%, p = 0.037) and higher levels of blood glucose (18.3% versus 11%, p = 0.037). According to correlation analyses, D-dimer levels were positively correlated with number of venous sinuses involvement (NVS) (r = 0.321, p = 0.009) in the EDG. Multivariate logistic regression analysis showed that SD (OR, 0.025; 95% CI, 1.324-6.043; p = 0.000), NVS (OR, 1.573; 95% CI, 1.15-2.151; p = 0.005) and risk factors (OR, 3.321; 95% CI, 1.451-7.564; p = 0.004) were significantly different between the two groups. D-dimer is elevated in patients with acute/subacute CVST.

  17. Camelliin B and nobotanin I, macrocyclic ellagitannin dimers and related dimers, and their antitumor activity.

    Science.gov (United States)

    Yoshida, T; Chou, T; Haba, K; Okano, Y; Shingu, T; Miyamoto, K; Koshiura, R; Okuda, T

    1989-11-01

    Camelliin B and nobotanin I, dimeric hydrolyzable tannins of a new class having macrocyclic structures, were isolated from Camellia japonica and Heterocentron roseum, respectively. Nobotanin G and H of the structures related to nobotanin I, were also obtained from H. roseum. Camelliin B and also woodfordin C, a macrocyclic dimer from Woodfordia fruticosa, exhibited marked host-mediated antitumor activities.

  18. Calix[4]arene supported clusters: a dimer of [Mn(III)Mn(II)] dimers

    DEFF Research Database (Denmark)

    Taylor, Stephanie M; McIntosh, Ruaraidh D; Beavers, Christine M

    2011-01-01

    Phosphinate ligands allow for the transformation of a calix[4]arene supported [Mn(III)(2)Mn(II)(2)] tetramer cluster motif into an unusual [Mn(III)Mn(II)](2) dimer of dimers; the clusters self-assemble in the crystal to form bi-layer arrays reminiscent of the typical packing of calixarene solvates....

  19. Effect of some pyrimidinic Schiff bases on the corrosion of mild steel in hydrochloric acid solution

    International Nuclear Information System (INIS)

    Ashassi-Sorkhabi, H.; Shaabani, B.; Seifzadeh, D.

    2005-01-01

    The efficiency of benzylidene-pyrimidin-2-yl-amine (A) (4-methyl-benzylidene)-pyrimidine-2-yl-amine (B) and (4-chloro-benzylidene)-pyrimidine-2-yl-amine, as corrosion inhibitors for mild steel in 1 M HCl have been determined by weight loss measurements and electrochemical polarization method. The results showed that these inhibitors revealed a good corrosion inhibition even at very low concentrations. Polarization curves indicate that all compounds are mixed type inhibitors. The effect of various parameters such as temperature and inhibitor concentration on the efficiency of the inhibitors has been studied. Activation energies of corrosion reaction in the presence and absence of inhibitors have been calculated. The adsorption of used compounds on the steel surface obeys Langmuir's isotherm. It appears that an efficient inhibition is characterized by a relatively greater decrease in free energy of adsorption. Significant correlations are obtained between inhibition efficiency and quantum chemical parameters using quantitative structure-activity relationship (QSAR) method

  20. Nucleobases and Other Prebiotic Species from the UV Irradiation of Pyrimidine in Astrophysical Ices

    Science.gov (United States)

    Sandford, Scott; Materese, Christopher; Nuevo, Michel

    2012-01-01

    Nucleobases are aromatic N-heterocycles that constitute the informational subunits of DNA and RNA and are divided into two families: pyrimidine bases (uracil, cytosine, and thymine) and purine bases (adenine and guanine). Nucleobases have been detected in meteorites and their extraterrestrial origin confirmed by isotope measurement. Although no N-heterocycles have been individually identified in the ISM, the 6.2-micron interstellar emission feature seen towards many astronomical objects suggests a population of such molecules is likely present. We report on a study of the formation of pyrimidine-based molecules, including nucleobases and other species of prebiotic interest, from the ultraviolet (UV) irradiation of pyrimidine in low temperature ices containing H2O, NH3, C3OH, and CH4, to simulate the astrophysical conditions under which prebiotic species may be formed in the Solar System.

  1. Development and survival of Drosophila melanogaster fed a diet containing pyrimidine analogs.

    Science.gov (United States)

    Ho, Y K; Clifford, A J

    1997-09-01

    A single generation of Drosophila melanogaster was raised on different media. One of the media was unsupplemented (the control) and the others were supplemented with pyrimidine analog at 10.3 mmol/kg culture medium. The relative numbers of larvae, pupae, and F1 adults reproduced from parent flies on each medium served as an indication of the relative toxicity of the supplements. The relative decreasing order of toxicity of the pyrimidines was as follows: 5-bromouracil < thymine < uracil = orotic acid = control = cytosine, control < UMP. The toxic effects of 5-bromouracil and thymine seem to be associated with the addition of a bromine or methyl group to carbon 5 of the pyrimidine ring. The UMP supplementation increased the number of adult F1 flies above the control group indicating that UMP was not only non toxic but also that it was beneficial.

  2. Microwave assisted synthesis and antimicrobial activity of some novel pyrimidine derivatives

    Directory of Open Access Journals (Sweden)

    S. J. VAGHASIA

    2007-02-01

    Full Text Available The synthesis of thiazolo [5,4-d]pyrimidines can be achieved from different 5-thiazolidinones, 2-butyl-1H-imidazole-5-carbaldehyde and thiourea using microwave irradiation within 5 min. The structures of the products were supported by FTIR, PMR and mass spectral data. The in vitro antimicrobial activity of the synthesized thiazolo [5,4-d]pyrimidines 1a-j, having substituents at the 1- and 3-positions, were determined by the cup-plate method against several standard strains chosen to define the spectrum and potency of the new compounds. The antimicrobial activities of the thiazolo [5,4-d]pyrimidines 1a-j are compared with those of known chosen standard drugs, viz. ampicillin, chloramphenicol, ciprofloxacin, norfloxacin and griseofulvin.

  3. Anti-parallel dimer and tetramer formation of propylene carbonate

    Directory of Open Access Journals (Sweden)

    Ayana Tagawa

    2017-09-01

    Full Text Available Raman scattering and infrared (IR absorption spectra of enantiopure (R-propylene carbonate ((RPC and racemic propylene carbonate (PC were recorded at room temperature, 25 °C, in benzene (Bz solution and in the pure liquid state to investigate the presence of dimers and other higher order intermolecular associations. (RPC and PC both demonstrated a strong C=O stretching vibrational band. The band exhibited changes in its shape and resonance wavenumber highly dependent on the concentrations of PCs, whereas a difference between the chirality of (RPC and PC had little influence. In an extremely dilute condition, doubly split bands were observed at 1807 and 1820 cm-1 in both Raman and IR spectra, which are assigned to the characteristic bands of isolated monomeric PCs. An additional band appeared at 1795 cm-1 in a dilute to concentrated regime, and its magnitude strengthened with increasing concentrations accompanied with slight increasing in the magnitude of 1807 cm-1 band in Raman spectra, while an increase in the magnitude of 1807 cm-1 band was clearly greater than that of 1795 cm-1 band in IR spectra. The spectrum changes at 1795 and 1807 cm-1 were attributed to characteristics of anti-parallel dimer formation of PCs caused by strong dipole-dipole interactions between C=O groups. Moreover, another additional signal was clearly observed at 1780-1790 cm-1 in a concentrated regime, and became the primary signal in the pure liquid state with slight increasing in the intensity of 1795 cm-1 band in Raman spectra. On the other hand, in IR spectra the observed increasing of 1780-1790 cm-1 band was much less than that of 1795 cm-1 band. These newly found spectrum changes in the concentrated regime are attributed to the formation of anti-parallel tetramers of PCs based on the characteristics of band selection rule found in Raman and IR spectra. Equilibrium constants for the anti-parallel dimer (KD and tetramer formation (KT of PCs in Bz solution and in

  4. Anti-parallel dimer and tetramer formation of propylene carbonate

    Science.gov (United States)

    Tagawa, Ayana; Numata, Tomoko; Shikata, Toshiyuki

    2017-09-01

    Raman scattering and infrared (IR) absorption spectra of enantiopure (R)-propylene carbonate ((R)PC) and racemic propylene carbonate (PC) were recorded at room temperature, 25 °C, in benzene (Bz) solution and in the pure liquid state to investigate the presence of dimers and other higher order intermolecular associations. (R)PC and PC both demonstrated a strong C=O stretching vibrational band. The band exhibited changes in its shape and resonance wavenumber highly dependent on the concentrations of PCs, whereas a difference between the chirality of (R)PC and PC had little influence. In an extremely dilute condition, doubly split bands were observed at 1807 and 1820 cm-1 in both Raman and IR spectra, which are assigned to the characteristic bands of isolated monomeric PCs. An additional band appeared at 1795 cm-1 in a dilute to concentrated regime, and its magnitude strengthened with increasing concentrations accompanied with slight increasing in the magnitude of 1807 cm-1 band in Raman spectra, while an increase in the magnitude of 1807 cm-1 band was clearly greater than that of 1795 cm-1 band in IR spectra. The spectrum changes at 1795 and 1807 cm-1 were attributed to characteristics of anti-parallel dimer formation of PCs caused by strong dipole-dipole interactions between C=O groups. Moreover, another additional signal was clearly observed at 1780-1790 cm-1 in a concentrated regime, and became the primary signal in the pure liquid state with slight increasing in the intensity of 1795 cm-1 band in Raman spectra. On the other hand, in IR spectra the observed increasing of 1780-1790 cm-1 band was much less than that of 1795 cm-1 band. These newly found spectrum changes in the concentrated regime are attributed to the formation of anti-parallel tetramers of PCs based on the characteristics of band selection rule found in Raman and IR spectra. Equilibrium constants for the anti-parallel dimer (KD) and tetramer formation (KT) of PCs in Bz solution and in the pure

  5. Dimerization of Protegrin-1 in Different Environments

    Directory of Open Access Journals (Sweden)

    Yiannis N. Kaznessis

    2010-09-01

    Full Text Available The dimerization of the cationic β-hairpin antimicrobial peptide protegrin-1 (PG1 is investigated in three different environments: water, the surface of a lipid bilayer membrane, and the core of the membrane. PG1 is known to kill bacteria by forming oligomeric membrane pores, which permeabilize the cells. PG1 dimers are found in two distinct, parallel and antiparallel, conformations, known as important intermediate structural units of the active pore oligomers. What is not clear is the sequence of events from PG1 monomers in solution to pores inside membranes. The step we focus on in this work is the dimerization of PG1. In particular, we are interested in determining where PG1 dimerization is most favorable. We use extensive molecular dynamics simulations to determine the potential of mean force as a function of distance between two PG1 monomers in the aqueous subphase, the surface of model lipid bilayers and the interior of these bilayers. We investigate the two known distinct modes of dimerization that result in either a parallel or an antiparallel β-sheet orientation. The model bilayer membranes are composed of anionic palmitoyl-oleoyl-phosphatidylglycerol (POPG and palmitoyl-oleoyl-phosphatidylethanolamine (POPE in a 1:3 ratio (POPG:POPE. We find the parallel PG1 dimer association to be more favorable than the antiparallel one in water and inside the membrane. However, we observe that the antiparallel PG1 β-sheet dimer conformation is somewhat more stable than the parallel dimer association at the surface of the membrane. We explore the role of hydrogen bonds and ionic bridges in peptide dimerization in the three environments. Detailed knowledge of how networks of ionic bridges and hydrogen bonds contribute to peptide stability is essential for the purpose of understanding the mechanism of action for membrane-active peptides as well as for designing peptides which can modulate membrane properties. The findings are suggestive of the

  6. Plasmonic nanospherical dimers for color pixels

    KAUST Repository

    Alrasheed, Salma

    2018-04-20

    Display technologies are evolving more toward higher resolution and miniaturization. Plasmonic color pixels can offer solutions to realize such technologies due to their sharp resonances and selective scattering and absorption at particular wavelengths. Metal nanosphere dimers are capable of supporting plasmon resonances that can be tuned to span the entire visible spectrum. In this article, we demonstrate numerically bright color pixels that are highly polarized and broadly tuned using periodic arrays of metal nanosphere dimers on a glass substrate. We show that it is possible to obtain RGB pixels in the reflection mode. The longitudinal plasmon resonance of nanosphere dimers along the axis of the dimer is the main contributor to the color of the pixel, while far-field diffractive coupling further enhances and tunes the plasmon resonance. The computational method used is the finite-difference time-domain method. The advantages of this approach include simplicity of the design, bright coloration, and highly polarized function. In addition, we show that it is possible to obtain different colors by varying the angle of incidence, the periodicity, the size of the dimer, the gap, and the substrate thickness.

  7. Multiply charged monopoles in cubic dimer model

    Science.gov (United States)

    Ganesh Jaya, Sreejith; Powell, Stephen

    2015-03-01

    The classical cubic dimer model is a 3D statistical mechanical system whose degrees of freedom are dimers that occupy the edges between nearest neighbour vertices of a cubic lattice. Dimer occupancies are subject to the local constraint that every vertex is associated with exactly one dimer. In the presence of an aligning interaction, it is known that the system exhibits an unconventional continuous thermal phase transition from a symmetry broken columnar phase to a Coulomb-phase. The transition is in the NCCP1 universality class, which also describes the Neel-VBS transition in the JQ model and the S =1/2 Heisenberg model with suppression of hedgehog defects. Using Monte-Carlo simulations of a pair of defects in a background of fluctuating dimers, we calculate the scaling exponents for fugacities of monopole defects of charge Q = 2 and 3 at this critical point. Our estimates suggest that Q = 3 monopoles are relevant and could therefore drive the JQ model away from the NCCP1 critical point on a hexagonal lattice.

  8. Dynamic interplay between adhesive and lateral E-cadherin dimers

    DEFF Research Database (Denmark)

    Klingelhöfer, Jörg; Laur, Oscar Y; Troyanovsky, Regina B

    2002-01-01

    E-cadherin, an adhesive transmembrane protein of epithelial adherens junctions, forms two types of detergent-resistant dimers: adhesive dimers consisting of cadherin molecules derived from two neighboring cells and lateral dimers incorporating cadherins of the same cell. Both dimers depend...... on the integrity of the same residue, Trp156. While the relative amounts of these complexes are not certain, we show here that in epithelial A-431 cells, adhesive dimers may be a prevalent form. Inactivation of the calcium-binding sites, located between successive cadherin ectodomains, drastically reduced...... the amount of adhesive dimers and concomitantly increased the amount of lateral dimers. A similar interdependence of adhesive and lateral dimers was observed in digitonin-permeabilized cells. In these cells, adhesive dimers immediately disassembled after lowering the Ca2+ concentration below 0.1 m...

  9. Nucleobases and other Prebiotic Species from the Ultraviolet Irradiation of Pyrimidine in Astrophysical Ices

    Science.gov (United States)

    Sandford, S. A.; Nuevo, M.; Materese, C. K.; Milam, S. N.

    2012-01-01

    Nucleobases are N-heterocycles that are the informational subunits of DNA and RNA, and are divided into two families: pyrimidine bases (uracil, cytosine, and thymine) and purine bases (adenine and guanine). Nucleobases have been detected in meteorites and their extraterrestrial origin confirmed by isotope measurement. Although no Nheterocycles have ever been observed in the ISM, the positions of the 6.2-m interstellar emission features suggest a population of such molecules is likely to be present. In this work we study the formation of pyrimidine-based molecules, including nucleobases, as well as other species of prebiotic interest, from the ultraviolet (UV) irradiation of pyrimidine in combinations of H2O, NH3, CH3OH, and CH4 ices at low temperature, in order to simulate the astrophysical conditions under which prebiotic species may be formed in the interstellar medium and icy bodies of the Solar System. Experimental: Gas mixtures are prepared in a glass mixing line (background pressure approx. 10(exp -6)-10(exp -5) mbar). Relative proportions between mixture components are determined by their partial pressures. Gas mixtures are then deposited on an aluminum foil attached to a cold finger (15-20 K) and simultaneously irradiated with an H2 lamp emitting UV photons (Lyman and a continuum at approx.160 nm). After irradiation samples are warmed to room temperature, at which time the remaining residues are recovered to be analyzed with liquid and gas chromatographies. Results: These experiments showed that the UV irradiation of pyrimidine mixed in these ices at low temperature leads to the formation of several photoproducts derived from pyrimidine, including the nucleobases uracil and cytosine, as well as their precursors 4(3H)-pyrimidone and 4-aminopyrimidine (Fig. 1). Theoretical quantum calculations on the formation of 4(3H)-pyrimidone and uracil from the irradiation of pyrimidine in pure H2O ices are in agreement with their experimental formation pathways. In

  10. Synthesis and biological properties of novel triazolopyrimido-pyrimidine-5,8-diones.

    Science.gov (United States)

    Dlugosz, A

    1989-10-01

    The synthesis of novel 1,2,4 triazolo[2,3,4-c,d]pyrimido[4,5-d]pyrimidine derivatives has been described from N-substituted amides of 1,2,3,4-tetrahydro-6-methyl-2-oxo-4-thio-5-pyrimidinecarboxylic acid 1. Amides 1 treated with 80% hydrazine hydrate, followed by aqueous-ethanolic formaldehyde form substituted triazolo[4,3-c]pyrimidines which cyclize in pyridine to triazolopyrimidopyrimidine derivatives 4. Attention has been paid to the synthesis of the 4-arylidenehydrazinopyrimidines 3. Some compounds have been tested for antibacterial and anticancer activities and for action on CNS.

  11. Photoionization of helium dimers; Photoionisation von Heliumdimeren

    Energy Technology Data Exchange (ETDEWEB)

    Havermeier, Tilo

    2010-06-09

    The helium dimer is one of the most weakly bound systems in the universe. This makes it an interesting quantum mechanical object for investigation. These Van der Waals Clusters can be produced in an expansion of a cryogenic gas jet through a small nozzle into vacuum. In the present experiment we examine the interaction of He dimers with synchrotron radiation at an energy range from 64 to 78 eV. We observed different pathways leading to single ionization of both He atoms of the dimer compound. This two close standing ions begin now to dissociate in cause of their coulomb potential. All charged fragments were detected in coincidence with a COLTRIMS system. Especially Interatomic Coulombic Decay (ICD) and the two step process (TS1) were clearly identified. Furthermore a distribution of the internuclear distance was obtained from the measured Kinetic Energy Release (KER). (orig.)

  12. Active thermochemical tables: water and water dimer.

    Science.gov (United States)

    Ruscic, Branko

    2013-11-21

    A new partition function for water dimer in the temperature range 200-500 K was developed by exploiting the equations of state for real water vapor, liquid water, and ice, and demonstrated to be significantly more accurate than any proposed so far in the literature. The new partition function allows the Active Thermochemical Tables (ATcT) approach to be applied on the available experimental and theoretical data relating to water dimer thermochemistry, leading to accurate water dimer enthalpies of formation of -499.115 ± 0.052 kJ mol(-1) at 298.15 K and -491.075 ± 0.080 kJ mol(-1) at 0 K. With the current ATcT enthalpy of formation of the water monomer, -241.831 ± 0.026 kJ mol(-1) at 298.15 K (-238.928 kJ mol(-1) at 0 K), this leads to the dimer bond dissociation enthalpy at 298.15 K of 15.454 ± 0.074 kJ mol(-1) and a 0 K bond dissociation energy of 13.220 ± 0.096 kJ mol(-1) (1105 ± 8 cm(-1)), the latter being in perfect agreement with recent experimental and theoretical determinations. The new partition function of water dimer allows the extraction and tabulation of heat capacity, entropy, enthalpy increment, reduced Gibbs energy, enthalpy of formation, and Gibbs energy of formation. Newly developed tabulations of analogous thermochemical properties for gas-phase water monomer and for water in condensed phases are also given, allowing the computations of accurate equilibria between the dimer and monomer in the 200-500 K range of temperatures.

  13. End binding proteins are obligatory dimers.

    Directory of Open Access Journals (Sweden)

    Indrani Sen

    Full Text Available End binding (EB proteins are responsible for the recruitment of an array of microtubule plus-end tracking proteins (+TIPs to growing microtubules ends. EBs encompass an N-terminal calponin homology domain that confers microtubule tip tracking activity to the protein. The C-terminal domain of EBs contains a coiled coil that mediates the parallel dimerization of EB monomers. This part of the protein is also responsible for partner binding. While dimerization is not essential for microtubule tip tracking by EBs it is a prerequisite for +TIP partner binding. The concentration of EBs in cells has been estimated to be in the range of hundreds of nanomoles. In contrast, in in vitro single molecule experiments EB concentrations of subnanomoles are employed. From a mechanistic point of view it is important to assess the oligomerization state of EBs at physiologically and experimentally relevant protein concentrations, in particular if the goal of a study is to model the behavior of EB-dependent dynamic +TIP networks. Here we have determined the stability of the EB1 and EB3 dimers using multi-angle light scattering and fluorescence analytical ultracentrifugation. We show that these EBs form stable dimers and do not dissociate even at very low nanomolar concentrations. The dimers remained stable at both room temperature as well as at the physiologically relevant temperature of 37°C. Together, our results reveal that EBs are obligatory dimers, a conclusion that has implications for the mechanistic understanding of these key proteins involved in the orchestration of dynamic protein networks at growing microtubule ends.

  14. On the asymptotics of dimers on tori

    OpenAIRE

    Kenyon, Richard W.; Sun, Nike; Wilson, David B.

    2013-01-01

    We study asymptotics of the dimer model on large toric graphs. Let $\\mathbb L$ be a weighted $\\mathbb{Z}^2$-periodic planar graph, and let $\\mathbb{Z}^2 E$ be a large-index sublattice of $\\mathbb{Z}^2$. For $\\mathbb L$ bipartite we show that the dimer partition function on the quotient $\\mathbb{L}/(\\mathbb{Z}^2 E)$ has the asymptotic expansion $\\exp[A f_0 + \\text{fsc} + o(1)]$, where $A$ is the area of $\\mathbb{L}/(\\mathbb{Z}^2 E)$, $f_0$ is the free energy density in the bulk, and $\\text{fsc...

  15. A Novel Dimer of α-Tocopherol

    Directory of Open Access Journals (Sweden)

    Anjan Patel

    2008-01-01

    Full Text Available Decomposition of the complex 4, formed between the α-tocopherol ortho-quinone methide (2 and NMMO, by fast heating from −78∘C to 70∘C in inert solvents produces a novel α-tocopherol dimer with 6H,12H-dibenzo[b,f][1,5]dioxocine structure (5 which—in contrast to the well-known spiro-dimer of α-tocopherol (3—is symmetrical. This is the first example of a direct reaction of the highly transient zwitterionic, aromatic precursor 2a in the formation of the ortho-quinone methide 2.

  16. Factorized ground state in dimerized spin chains

    Energy Technology Data Exchange (ETDEWEB)

    Giorgi, Gian Luca, E-mail: gianluca@ifisc.uib-csic.e [Institute for Cross-Disciplinary Physics and Complex Systems, IFISC (CSIC-UIB), Campus Universitat Illes Balears, E-07122 Palma de Mallorca (Spain)

    2010-09-01

    The possibility of observing factorized ground states in dimerized spin systems is studied. A set of sufficient conditions is derived which allows one to establish whether or not it is possible to have factorization both in nearest-neighbour and long-range Hamiltonians. These conditions can be derived by forcing factorization for each of the pairwise terms of the total Hamiltonian. Due to the peculiar structure of a dimerized chain, an antiferromagnetic factorized ground state of the kind |nearr), |nearr), |nwarr), |nwarr) (forbidden in regular chains) is possible.

  17. Repair of UV dimers in skin DNA of patients with basal cell carcinoma.

    Science.gov (United States)

    Segerbäck, Dan; Strozyk, Malgorzata; Snellman, Erna; Hemminki, Kari

    2008-09-01

    Epidemiologic studies suggest that exposure to sunlight is the primary etiologic agent for basal cell carcinoma. Formation of UV-induced DNA damage is believed to be a crucial event in the process leading to skin cancer. In this study, repair of photoproducts in DNA was followed in the skin of patients with basal cell carcinoma and control subjects. The subjects were exposed to 800 J/m(2) Commission Internationale de 1'Eclairag of solar-simulating radiation on buttock skin. Biopsies were taken at 0 hour, 24 hours, and 3 weeks after the exposure. Two cyclobutane pyrimidine dimers, TT=C and TT=T, were measured using a sensitive (32)P-postlabeling assay. Initial levels of both TT=C and TT=T differed between individuals in both groups. The levels of TT=T in patients with basal cell carcinoma and controls were similar (9.9 +/- 4.0 and 9.2 +/- 2.9 products per 10(6) normal nucleotides), whereas the level of TT=C was significantly lower in controls than in patients with basal cell carcinoma (6.2 +/- 3.1 versus 10.9 +/- 4.5 products per 10(6) normal nucleotides). The fractions of TT=T remaining after 24 hours and 3 weeks were significantly higher in patients with basal cell carcinoma (72% and 11%) compared with controls (48% and 5%). A slower removal in patients with basal cell carcinoma than in controls was indicated also for TT=C (52% versus 42% remaining at 24 hours); however, the difference between groups was not significant. When including data from our previously reported small-scale study, the fraction of dimers remaining at 24 hours was significantly higher in patients with basal cell carcinoma for both TT=C and TT=T. The data suggest that patients with basal cell carcinoma have a reduced capacity to repair UV-induced DNA lesions.

  18. Splitting strings on integrable backgrounds

    International Nuclear Information System (INIS)

    Vicedo, Benoit

    2011-05-01

    We use integrability to construct the general classical splitting string solution on R x S 3 . Namely, given any incoming string solution satisfying a necessary self-intersection property at some given instant in time, we use the integrability of the worldsheet σ-model to construct the pair of outgoing strings resulting from a split. The solution for each outgoing string is expressed recursively through a sequence of dressing transformations, the parameters of which are determined by the solutions to Birkhoff factorization problems in an appropriate real form of the loop group of SL 2 (C). (orig.)

  19. Intramolecular Diels-Alder reactions of pyrimidines, a synthetic and computational study

    NARCIS (Netherlands)

    Stolle, W.A.W.

    1992-01-01

    This thesis deals with an investigation on the ringtransformation reactions of 2and 5-(ω-alkynyl)pyrimidine derivatives, which undergo upon heating an intramolecular Diels-Alder reaction and subsequently a spontaneous retro Diels- Alder reaction. To get a better insight into the

  20. An Efficient and Facile Methodology for Bromination of Pyrimidine and Purine Nucleosides with Sodium Monobromoisocyanurate (SMBI

    Directory of Open Access Journals (Sweden)

    Roger Stromberg

    2013-10-01

    Full Text Available An efficient and facile strategy has been developed for bromination of nucleosides using sodium monobromoisocyanurate (SMBI. Our methodology demonstrates bromination at the C-5 position of pyrimidine nucleosides and the C-8 position of purine nucleosides. Unprotected and also several protected nucleosides were brominated in moderate to high yields following this procedure.

  1. Blockage of the pyrimidine biosynthetic pathway affects riboflavin production in Ashbya gossypii.

    Science.gov (United States)

    Silva, Rui; Aguiar, Tatiana Q; Domingues, Lucília

    2015-01-10

    The Ashbya gossypii riboflavin biosynthetic pathway and its connection with the purine pathway have been well studied. However, the outcome of genetic alterations in the pyrimidine pathway on riboflavin production by A. gossypii had not yet been assessed. Here, we report that the blockage of the de novo pyrimidine biosynthetic pathway in the recently generated A. gossypii Agura3 uridine/uracil auxotrophic strain led to improved riboflavin production on standard agar-solidified complex medium. When extra uridine/uracil was supplied, the production of riboflavin by this auxotroph was repressed. High concentrations of uracil hampered this (and the parent) strain growth, whereas excess uridine favored the A. gossypii Agura3 growth. Considering that the riboflavin and the pyrimidine pathways share the same precursors and that riboflavin overproduction may be triggered by nutritional stress, we suggest that overproduction of riboflavin by the A. gossypii Agura3 may occur as an outcome of a nutritional stress response and/or of an increased availability in precursors for riboflavin biosynthesis, due to their reduced consumption by the pyrimidine pathway. Copyright © 2014 Elsevier B.V. All rights reserved.

  2. Quantitative analysis of the pyrimidine metabolism in pheochromocytoma PC-12 cells

    NARCIS (Netherlands)

    Slingerland, R. J.; van Gennip, A. H.; Bodlaender, J. M.; Voûte, P. A.; van Kuilenburg, A. B.

    1995-01-01

    A detailed quantitative study of pyrimidine metabolism in exponentially growing rat pheochromocytoma PC-12 cells has been performed. The sizes of ribonucleotide pools have been analysed and the pathways and the rates of metabolism of uridine, cytidine and aspartic acid have been determined, based on

  3. ESR study of radiation damage in pyrimidines. Progress report, August 1, 1975--April 1, 1976

    International Nuclear Information System (INIS)

    Benson, B.W.

    1976-04-01

    The primary objective of this project is to develop general mechanisms for radiation damage to biomolecules using substituted pyrimidines as a model system. Results this year include a single crystal ESR study of 5-ethyl-5-isopropylbarbituric acid, development of the k-band microwave bridge, dose response measurements on methylated barbituric acid derivatives, and synthesis of several specifically deuterated uracil derivatives

  4. Proteomics reveals reduced expression of tansketolase in pyrimidine 5'-nucleotidase deficient patients

    NARCIS (Netherlands)

    Barasa, Benjamim; van Oirschot - Hermans, B.A.; Bianchi, P.; van Solinge, WW; Heck, Albert J R; van Wijk, HA; Slijper, M.

    Purpose To date, it remains a challenge to correctly and timely diagnose red blood cell (RBC) enzymopathies that result in hereditary nonspherocytic hemolytic anemia (HNSHA), the third most common of which is pyrimidine 5′-nucleotidase (P5N) deficiency with just over 100 cases recognized and

  5. An efficient synthesis of pyrazolo[1,5-a]pyrimidines and evaluation of ...

    Indian Academy of Sciences (India)

    An efficient synthesis of pyrazolo[1,5-a]pyrimidines and evaluation of their antimicrobial activity. SOMESHWAR DESHMUKH, KUNAL DINGORE, VISHWAS GAIKWAD and. MADHUKAR JACHAK. ∗. Organic Chemistry Research Center, Department of Chemistry, K T H M College, Affiliated to Savitribai. Phule Pune University ...

  6. Synthesis of 4-aryl-4, 5-dihydro-1-indeno [1, 2-] pyrimidines by ...

    Indian Academy of Sciences (India)

    Home; Journals; Journal of Chemical Sciences; Volume 123; Issue 4. Synthesis of 4-aryl-4,5-dihydro-1-indeno[1,2-]pyrimidines by Biginelli condensation and their antibacterial activities. Ramandeep Kaur Monika Bansal Balbir Kaur Tulika Mishra Aruna Bhatia. Volume 123 Issue 4 July 2011 pp 443-451 ...

  7. The pyrimidine operon pyrRPB-carA from Lactococcus lactis

    DEFF Research Database (Denmark)

    Martinussen, Jan; Schallert, J.; Andersen, Birgit

    2001-01-01

    The four genes pyrR, pyrP, pyrB, and carA were found to constitute an operon in Lactococcus lactis subsp, lactis MG1363. The functions of the different genes were established by mutational analysis. The first gene in the operon is the pyrimidine regulatory gene, pyrR, which is responsible...

  8. Divalent metal complexes of 4-amino-N-pyrimidin-2-ylbenzene ...

    African Journals Online (AJOL)

    In all the complexes the metal ions coordinate through pyrimidinic nitrogen and sulphonamidic nitrogen of the two molecules of APS. The suggested structure for Cd(II) complex of APS is tetrahedral, while that of Cu(II), Mn(II) and Ni(II) APS complexes is octahedral. The inner coordination spheres were occupied by two water ...

  9. The Photochemistry of Pyrimidine in Pure H2O Ice Subjected to Different Radiation Environments and the Formation of Uracil

    Science.gov (United States)

    Nuevo, M.; Chen, Y.-J.; Materese. C. K..; Hu, W.-J.; Qiu, J.-M.; Wu, S.-R.; Fung, H.-S.; Sandford, S. A.; Chu, C.-C.; Yih, T.-S.; hide

    2013-01-01

    Nucleobases are N-heterocycles which are the informational subunits of DNA and RNA. They include pyrimidine bases (uracil, cytosine, and thymine) and purine bases (adenine and guanine). Nucleobases have been detected in several meteorites, although no Nheterocycles have been observed in space to data. Laboratory experiments showed that the ultraviolet (UV) irradiation of pyrimidine in pure H2O ice at low temperature (<=20 K) leads to the formation of pyrimidine derivatives including the nucleobase uracil and its precursor 4(3H)-pyrimidone. These results were confirmed by quantum chemical calculations. When pyrimidine is mixed with combinations of H2O, NH3, CH3OH, and CH4 ices under similar conditions, uracil and cytosine are formed. In the present work we study the formation of 4(3H)-pyrimidone and uracil from the irradiation of pyrimidine in H2O ice with high-energy UV photons (Lyman , He I, and He II lines) provided by a synchrotron source. The photo-destruction of pyrimidine in these H2O ices as well as the formation yields for 4(3H)-pyrimidone and uracil are compared with our previous results in order to study the photo-stability of pyrimidine and the production efficiency of uracil as a function of the photon energy.

  10. Split supersymmetry in brane models

    Indian Academy of Sciences (India)

    Type-I string theory in the presence of internal magnetic fields provides a concrete realization of split supersymmetry. To lowest order, gauginos are massless while squarks and sleptons are superheavy. For weak magnetic fields, the correct Standard Model spectrum guarantees gauge coupling unification with sin2 W ...

  11. VBSCan Split 2017 Workshop Summary

    Energy Technology Data Exchange (ETDEWEB)

    Anders, Christoph Falk; et al.

    2018-01-12

    This document summarises the talks and discussions happened during the VBSCan Split17 workshop, the first general meeting of the VBSCan COST Action network. This collaboration is aiming at a consistent and coordinated study of vector-boson scattering from the phenomenological and experimental point of view, for the best exploitation of the data that will be delivered by existing and future particle colliders.

  12. Split supersymmetry in brane models

    Indian Academy of Sciences (India)

    journal of. November 2006 physics pp. 793–802. Split supersymmetry in brane models. IGNATIOS ANTONIADIS∗. Department of Physics, CERN-Theory Division, 1211 Geneva 23, Switzerland. E-mail: Ignatios. ... that LEP data favor the unification of the three SM gauge couplings are smoking guns for the presence of new ...

  13. Water splitting by cooperative catalysis

    NARCIS (Netherlands)

    Hetterscheid, D.G.H.; van der Vlugt, J.I.; de Bruin, B.; Reek, J.N.H.

    2009-01-01

    A mononuclear Ru complex is shown to efficiently split water into H2 and O2 in consecutive steps through a heat- and light-driven process (see picture). Thermally driven H2 formation involves the aid of a non-innocent ligand scaffold, while dioxygen is generated by initial photochemically induced

  14. On split Lie triple systems

    Indian Academy of Sciences (India)

    Lie triple system; system of roots; root space; split Lie algebra; structure theory. 1. Introduction and previous definitions. Throughout this paper, Lie triple systems T are considered of arbitrary dimension and over an arbitrary field K. It is worth to mention that, unless otherwise stated, there is not any restriction on dim Tα or {k ...

  15. On split Lie triple systems

    Indian Academy of Sciences (India)

    The key tool in this job is the notion of connection of roots in the framework of split Lie triple systems. Author Affiliations. Antonio J Calderón Martín1. Departamento de Matemáticas, Universidad de Cádiz, 11510 Puerto Real, Cádiz, Spain. Dates. Manuscript received: 25 January 2008. Proceedings – Mathematical Sciences.

  16. Evidence that the Yeast Desaturase Ole1p Exists as a Dimer In Vivo

    Energy Technology Data Exchange (ETDEWEB)

    Lou, Y.; Shanklin, J.

    2010-06-18

    Desaturase enzymes are composed of two classes, the structurally well characterized soluble class found predominantly in the plastids of higher plants and the more widely distributed but poorly structurally defined integral membrane class. Despite their distinct evolutionary origins, the two classes both require an iron cofactor and molecular oxygen for activity and are inhibited by azide and cyanide, suggesting strong mechanistic similarities. The fact that the soluble desaturase is active as a homodimer prompted us test the hypothesis that an archetypal integral membrane desaturase from Saccharomyces cerevisiae, the {Delta}{sup o}-acyl-Co-A desaturase Ole1p, also exhibits a dimeric organization. Ole1p was chosen because it is one of the best characterized integral membrane desaturase and because it retains activity when fused with epitope tags. FLAG-Ole1p was detected by Western blotting of immunoprecipitates in which anti-Myc antibodies were used for capture from yeast extracts co-expressing Ole1p-Myc and Ole1p-FLAG. Interaction was confirmed by two independent bimolecular complementation assays (i.e. the split ubiquitin system and the split luciferase system). Co-expression of active and inactive Ole1p subunits resulted in an {approx}75% suppression of the accumulation of palmitoleic acid, demonstrating that the physiologically active form of Ole1p in vivo is the dimer in which both protomers must be functional.

  17. Stability and Formation of Isobutylene Dimers.

    Science.gov (United States)

    Goldsmith, Robert H.

    1983-01-01

    Isobutylene is an important bulk chemical for the petroleum industry. Dimerization and hydrogenation reactions produce the standard fuel octane rating comparison. This classic chemistry is often misrepresented in modern texts, however, and this paper attempts to correlate the physical organic principles that apply. (Author)

  18. Spectroscopic Observation of CS_2 Dimer

    Science.gov (United States)

    Rezaei, M.; Oliaee, J. Norooz; Moazzen-Ahmadi, N.; McKellar, A. R. W.

    2011-06-01

    Infrared spectra of the CS_2 dimer are observed in the region of the CS_2 ν_3 fundamental band (˜ 1535 Cm-1) using a tuneable diode laser spectrometer. The weakly-bound complex is formed in a pulsed supersonic slit-jet expansion of a dilute gas mixture of carbon disulfide in helium. Contrary to the planar slipped-parallel geometry previously observed for (CO_2)_2, (N_2O)_2 and (OCS)_2, the CS_2 dimer exhibits a cross-shaped structure with D2d symmetry. Two bands were observed and analyzed: the fundamental (C-S asymmetric stretch) and a combination involving this mode plus an intermolecular vibration. In both cases, the rotational structure corresponds to a perpendicular (Δ K = ± 1) band of a symmetric rotor molecule. The intermolecular center of mass separation (C-C distance) is determined to be 3.539(7) {Å}. Thanks to symmetry, this is the only parameter required to characterize the structure, if the monomer geometry is assumed to remain unchanged in the dimer. From the band centers of the fundamental and combination band an intermolecular frequency of 10.96 Cm-1 is obtained, which we assign as the torsional bending mode. This constitutes the first high resolution spectroscopic investigation of CS_2 dimer.

  19. Synthesis and characterization of monomeric and dimeric ...

    African Journals Online (AJOL)

    The two complexes are isostructural, with the central metal atom lying on a crystallographic 2-fold axis. Both complexes are approximately octahedral, the coordination being provided by two trans pyridine nitrogen atoms and two cis amine nitrogen atoms from the oxime ligands, and by two cis chlorides. The dimeric ...

  20. Microwave spectra and structure of the cyclopropanecarboxylic acid-formic acid dimer

    Energy Technology Data Exchange (ETDEWEB)

    Pejlovas, Aaron M.; Kukolich, Stephen G. [Department of Chemistry and Biochemistry, University of Arizona, Tucson, Arizona 85721 (United States); Lin, Wei [Department of Chemistry, University of Texas Rio Grande Valley, Brownsville, Texas 78520 (United States)

    2015-09-28

    The rotational spectrum of the cyclopropanecarboxylic acid–formic acid doubly hydrogen bonded dimer has been measured in the 4-11 GHz region using a Flygare-Balle type pulsed-beam Fourier transform microwave spectrometer. Rotational transitions were measured for the parent, four unique singly substituted {sup 13}C isotopologues, and a singly deuterated isotopologue. Splittings due to a possible concerted double proton tunneling motion were not observed. Rotational constants (A, B, and C) and centrifugal distortion constants (D{sub J} and D{sub JK}) were determined from the measured transitions for the dimer. The values of the rotational (in MHz) and centrifugal distortion constants (in kHz) for the parent isotopologue are A = 4045.4193(16), B = 740.583 80(14), C = 658.567 60(23), D{sub J} = 0.0499(16), and D{sub JK} = 0.108(14). A partial gas phase structure of the dimer was derived from the rotational constants of the measured isotopologues, previous structural work on each monomer units and results of the calculations.

  1. Evidence for the Formation of Pyrimidine Cations from the Sequential Reactions of Hydrogen Cyanide with the Acetylene Radical Cation.

    Science.gov (United States)

    Hamid, Ahmed M; Bera, Partha P; Lee, Timothy J; Aziz, Saadullah G; Alyoubi, Abdulrahman O; El-Shall, M Samy

    2014-10-02

    Herein, we report the first direct evidence for the formation of pyrimidine ion isomers by sequential reactions of HCN with the acetylene radical cation in the gas phase at ambient temperature using the mass-selected variable temperature and pressure ion mobility technique. The formation and structures of the pyrimidine ion isomers are theoretically predicted via coupled cluster and density functional theory calculations. This ion-molecule synthesis may indicate that pyrimidine is produced in the gas phase in space environments before being incorporated into condensed-phase ices and transformed into nucleic acid bases such as uracil.

  2. Determination of the Tetramer-Dimer Equilibrium Constant of Rabbit ...

    African Journals Online (AJOL)

    Hemoglobin is a tetrameric protein which is able to dissociate into dimers. The dimers can in turn dissociate into tetramers. It has been found that dimers are more reactive than tetramers. The difference in the reactivity of these two species has been used to determine the tetramerdimer dissociation constant of various ...

  3. Stochastic optimization-based study of dimerization kinetics

    Indian Academy of Sciences (India)

    Keywords. Stochastic optimization; dimerization kinetics; sensitivity analysis; stochastic simulation algorithm; probability distribution function. ... To this end, we study dimerization kinetics of protein as a model system. We follow the dimerization kinetics using a stochastic simulation algorithm and combine it with three ...

  4. Ultraviolet Spectrum And Chemical Reactivity Of CIO Dimer

    Science.gov (United States)

    Demore, William B.; Tschuikow-Roux, E.

    1992-01-01

    Report describes experimental study of ultraviolet spectrum and chemical reactivity of dimer of chlorine monoxide (CIO). Objectives are to measure absorption cross sections of dimer at near-ultraviolet wavelengths; determine whether asymmetrical isomer (CIOCIO) exists at temperatures relevant to Antarctic stratosphere; and test for certain chemical reactions of dimer. Important in photochemistry of Antarctic stratosphere.

  5. Ethanol water azeotrope Study. Molecular characterization of ethanol dimers, hetero dimers and hetero trimers of ethanol water

    International Nuclear Information System (INIS)

    Mejia, Sol M; Espinal, Juan F; Mondragon, Fanor

    2006-01-01

    In this investigation, as a first stage, we studied the structure and stability of the dimers,hetero dimers and hetero trimers like aggregates of ethanol and ethanol water respectively. Molecular modelling using hybrid B3LYP of the density functional theory (DFT) was used in this research. O-H bond lengths, hydrogen bond distances, CCOH dihedral angles, enthalpies and Gibbs free energies of dimerization and trimerization and vibrational frequencies of stretching O-H for the dimers and hetero dimers in function of the redshift undergone by proton donor molecules were analyzed. The results shows that the monomers arrange into aggregates which undergo geometric changes induced by the hydrogen bonds. For hetero dimers and hetero trimers the enhancement of the hydrogen bonds where the proton donor molecule corresponds to water was observed. In general, the dimers are more stable than the hetero dimers. We propose the formation of C-H-O hydrogen bonds in some hetero trimers

  6. New natural product -an efficient antimicrobial applications of new newly synthesized pyrimidine derivatives by the electrochemical oxidation of hydroxyl phenol in the presence of 2-mercapto-6-(trifluoromethyl) pyrimidine-4-ol as nucleophile.

    Science.gov (United States)

    Khan, Zia Ul Haq; Khan, Amjad; Wan, Pingyu; Khan, Arif Ullah; Tahir, Kamran; Muhammad, Nawshad; Khan, Faheem Ullah; Shah, Hidayat Ullah; Khan, Zia Ullah

    2018-05-01

    Some new pyrimidine derivatives have been synthesised by electrochemical oxidation of catechol (1a) in the existence of 2-mercapto-6-(trifluoromethyl) pyrimidine-4-ol (3) as a nucleophile in aqueous solution using Cyclic Voltammetric and Controlled Potential Coulometry. The catechol has been oxidised to o-quinone through electrochemical method and participative in Michael addition reaction, leading to the development of some new pyrimidine derivatives. The products were achieved in good yield with high pureness. The mechanism of the reaction has been conformed from the Cyclic Voltammetric data and Controlled Potential Coulometry. After purification, the compounds were characterised using modern techniques. The synthesised materials were screened for antimicrobial actions using Gram positive and Gram negative strain of bacteria. These new synthesised pyrimidine derivatives showed very good antimicrobial activity.

  7. Stability of split Stirling refrigerators

    International Nuclear Information System (INIS)

    Waele, A T A M de; Liang, W

    2009-01-01

    In many thermal systems spontaneous mechanical oscillations are generated under the influence of large temperature gradients. Well-known examples are Taconis oscillations in liquid-helium cryostats and oscillations in thermoacoustic systems. In split Stirling refrigerators the compressor and the cold finger are connected by a flexible tube. The displacer in the cold head is suspended by a spring. Its motion is pneumatically driven by the pressure oscillations generated by the compressor. In this paper we give the basic dynamic equations of split Stirling refrigerators and investigate the possibility of spontaneous mechanical oscillations if a large temperature gradient develops in the cold finger, e.g. during or after cool down. These oscillations would be superimposed on the pressure oscillations of the compressor and could ruin the cooler performance.

  8. Large D-Dimer Fluctuation in Normal Pregnancy

    DEFF Research Database (Denmark)

    Hedengran, Katrine K; Andersen, Malene R; Stender, Steen

    2016-01-01

    Introduction. D-dimer levels increase throughout pregnancy, hampering the usefulness of the conventional threshold for dismissing thromboembolism. This study investigates the biological fluctuation of D-dimer in normal pregnancy. Methods. A total of 801 healthy women with expected normal...... pregnancies were recruited. D-dimer was repeatedly measured during pregnancy, at active labor, and on the first and second postpartum days. Percentiles for each gestational week were calculated. Each individual D-dimer was normalized by transformation into percentiles for the relevant gestational age...... normal pregnancy, repeated D-dimer measurements are of no clinical use in the evaluation of thromboembolic events during pregnancy....

  9. Geometrical Applications of Split Octonions

    Directory of Open Access Journals (Sweden)

    Merab Gogberashvili

    2015-01-01

    Full Text Available It is shown that physical signals and space-time intervals modeled on split-octonion geometry naturally exhibit properties from conventional (3 + 1-theory (e.g., number of dimensions, existence of maximal velocities, Heisenberg uncertainty, and particle generations. This paper demonstrates these properties using an explicit representation of the automorphisms on split-octonions, the noncompact form of the exceptional Lie group G2. This group generates specific rotations of (3 + 4-vector parts of split octonions with three extra time-like coordinates and in infinitesimal limit imitates standard Poincare transformations. In this picture translations are represented by noncompact Lorentz-type rotations towards the extra time-like coordinates. It is shown how the G2 algebra’s chirality yields an intrinsic left-right asymmetry of a certain 3-vector (spin, as well as a parity violating effect on light emitted by a moving quantum system. Elementary particles are connected with the special elements of the algebra which nullify octonionic intervals. Then the zero-norm conditions lead to free particle Lagrangians, which allow virtual trajectories also and exhibit the appearance of spatial horizons governing by mass parameters.

  10. 7 CFR 51.2002 - Split shell.

    Science.gov (United States)

    2010-01-01

    ... 7 Agriculture 2 2010-01-01 2010-01-01 false Split shell. 51.2002 Section 51.2002 Agriculture... Standards for Grades of Filberts in the Shell 1 Definitions § 51.2002 Split shell. Split shell means a shell... of the shell, measured in the direction of the crack. ...

  11. Powerful methods to establish chromosomal markers in Lactococcus lactis: an analysis of pyrimidine salvage pathway mutants obtained by positive selections

    DEFF Research Database (Denmark)

    Martinussen, Jan; Hammer, Karin

    1995-01-01

    Using different 5-fluoropyrimidine analogues, positive selection procedures for obtaining mutants blocked in pyrimidine and purine salvage genes of Lactococcus lactis were established. Strains lacking the following enzyme activities due to mutations in the corresponding genes were isolated: uracil...

  12. Effect of donor-acceptor chromophores on photophysical properties of newly synthesized pyrazolo-pyrrolo-pyrimidines (PPP).

    Science.gov (United States)

    Rote, Ramhari V; Shelar, Deepak P; Patil, Sandeep R; Shinde, Santosh S; Toche, Raghunath B; Jachak, Madhukar N

    2011-01-01

    Novel pyrazolo-pyrrolo-pyrimidine (PPP) derivatives having remarkable photophysical properties are designed with the help of theoretical semiempirical calculations. These compounds then synthesized successfully and studied effect of substituents on its photophysical properties.

  13. Powerful methods to establish chromosomal markers in Lactococcus lactis: an analysis of pyrimidine salvage pathway mutants obtained by positive selections

    DEFF Research Database (Denmark)

    Martinussen, Jan; Hammer, Karin

    1995-01-01

    Using different 5-fluoropyrimidine analogues, positive selection procedures for obtaining mutants blocked in pyrimidine and purine salvage genes of Lactococcus lactis were established. Strains lacking the following enzyme activities due to mutations in the corresponding genes were isolated: uracil...... phosphoribosyltransferase (upp), uridindcytidine kinase (udk), pyrimidine nucleoside phosphorylase (pdp), cytidine/deoxycytidine deaminase (dd), thymidine kinase (tdk) and purine nucleoride phosphorylase (pup). Based on an analysis of the mutants obtained, the pathways by which L. lactis metabolizes uracil...... and the different pyrimidine nucleosides were verified. The substrate specificities of the different enzymes were determined. It was demonstrated that a single pyrimidine nucleoside phosphorylase accounts for the phosphorolytical cleavage of uridine, deoxyuridine and thymidine, and a single purine nucleoside...

  14. Synthesis, Structural Studies and Antitumoral Evaluation of C-6 Alkyl and Alkenyl Side Chain Pyrimidine Derivatives S

    Directory of Open Access Journals (Sweden)

    Marijeta Kralj

    2009-11-01

    Full Text Available The synthetic route for introduction of fluorophenylalkyl (compounds 5, 7, 14 and 15 and fluorophenylalkenyl (compounds 4E and 13 side chains at C-6 of the pyrimidine nucleus involved the lithiation of the pyrimidine derivatives 1, 2 and 11 and subsequent nucleophilic addition or substitution reactions of the organolithium intermediate thus obtained with 2-fluorophenylacetone, 4-fluoroacetophenone or ethyl 4-fluorobenzoate as electrophiles. The structures of novel compounds were confirmed by 1H-, 19F- and 13C-NMR and MS. Compounds 8 and 10 containing unsaturated fluorophenylalkyl side chains showed better inhibitory effect than their saturated fluorophenylalkylated pyrimidine counterparts 7 and 9. A conformational study based on NOE enhancements showed the importance of the double bond and substitution in the side chain for the conformational preferences in relation to inhibitory activity. Among all tested compounds, C-5 furyl (12 and phenyl (13 and 15 substituted pyrimidine derivatives showed significant cytostatic activities against all tested tumor cell lines.

  15. Simple approach to thieno[3,2-d]pyrimidines as new scaffolds of antimicrobial activities

    Directory of Open Access Journals (Sweden)

    Hafez Hend N.

    2016-09-01

    Full Text Available 6ʹ-(4-Chlorophenyl-spiro[cyclohexane-1,2ʹ-thieno[3,2-d][1,3] oxazin]-4ʹ(1ʹH-one (1 was synthesized and used as a starting material for the synthesis of a novel series of spiro compounds having biologically active sulfonamide 2a-e and 3ʹ-(4-acetylphenyl-6ʹ- (4-chlorophenyl-1ʹH-spiro[cyclohexane-1,2ʹ-thieno[3,2-d] pyrimidine-4ʹ(3ʹH-one (3. Compound 2a was used as a key intermediate for the synthesis of sulfonyl carbothioamide derivatives 4a-c. Also, compound 3 was used as an intermediate for the synthesis of 3ʹH-spiro[cyclohexane-1,2ʹ-thieno[3,2-d]pyrimidin]-3ʹ-yl] phenyl}-2-imino-4-(substituted phenyl and/or thienyl-1,2-dihydropyridine- 3-carbonitrile derivatives 5a-e, 3ʹH-spiro[cyclohexane- 1,2ʹ- thieno[3,2-d]pyrimidin]-3ʹ-yl]phenyl}-2-oxo-4-(substituted phenyl and/or thienyl-1,2-dihydropyridine-3-carbonitrile derivatives 6a-e, and 4-[(2Z-3-substituted-arylprop-2-enoyl] phenyl-1ʹH-spiro[cyclohexane-1,2ʹ-thieno[3,2-d]pyrimidine derivatives 7a-e. Cyclocondensation of 7a-e with hydrazine hydrate produced 6ʹ-(4-chlorophenyl-3ʹ-[4-(5-substituted aryl-4,5-dihydro- 1H-pyrazol-3-ylphenyl]-1ʹH-spiro[cyclohexane-1,2ʹ-thieno- [3,2-d]pyrimidin]-4ʹ(3ʹH-ones 8a-e but with hydroxylamine hydrochloride afforded the corresponding isoxazoline derivatives 9a-e. Also, cyclocondensation by thiourea afforded 2-thioxo-1,2- dihydropyrimidin-4-yl-phenyl-spiro-{cyclohexanethieno[3,2-d] pyrimidin}-4-one derivatives 10a-e. The new compounds were investigated for antimicrobial activity. Compounds 2c, 8b,c, 9b and 10b were the most potent ones against both Gram-negative and Gram-positive bacteria. Compound 8c exhibited higher antifungal activity towards the examined fungi with MIC of 1-2 μmol mL-1 compared to ketoconazole (MIC 2-3 μmol mL-1 .

  16. Fibrillar dimer formation of islet amyloid polypeptides

    Energy Technology Data Exchange (ETDEWEB)

    Chiu, Chi-cheng [Univ. of Chicago, IL (United States); Argonne National Lab. (ANL), Argonne, IL (United States); de Pablo, Juan J. [Univ. of Chicago, IL (United States); Argonne National Lab. (ANL), Argonne, IL (United States)

    2015-05-08

    Amyloid deposits of human islet amyloid polypeptide (hIAPP), a 37-residue hormone co-produced with insulin, have been implicated in the development of type 2 diabetes. Residues 20 – 29 of hIAPP have been proposed to constitute the amyloidogenic core for the aggregation process, yet the segment is mostly unstructured in the mature fibril, according to solid-state NMR data. Here we use molecular simulations combined with bias-exchange metadynamics to characterize the conformational free energies of hIAPP fibrillar dimer and its derivative, pramlintide. We show that residues 20 – 29 are involved in an intermediate that exhibits transient β-sheets, consistent with recent experimental and simulation results. By comparing the aggregation of hIAPP and pramlintide, we illustrate the effects of proline residues on inhibition of the dimerization of IAPP. The mechanistic insights presented here could be useful for development of therapeutic inhibitors of hIAPP amyloid formation.

  17. Fibrillar dimer formation of islet amyloid polypeptides

    Science.gov (United States)

    Chiu, Chi-cheng; de Pablo, Juan J.

    2015-09-01

    Amyloid deposits of human islet amyloid polypeptide (hIAPP), a 37-residue hormone co-produced with insulin, have been implicated in the development of type 2 diabetes. Residues 20 - 29 of hIAPP have been proposed to constitute the amyloidogenic core for the aggregation process, yet the segment is mostly unstructured in the mature fibril, according to solid-state NMR data. Here we use molecular simulations combined with bias-exchange metadynamics to characterize the conformational free energies of hIAPP fibrillar dimer and its derivative, pramlintide. We show that residues 20 - 29 are involved in an intermediate that exhibits transient β-sheets, consistent with recent experimental and simulation results. By comparing the aggregation of hIAPP and pramlintide, we illustrate the effects of proline residues on inhibition of the dimerization of IAPP. The mechanistic insights presented here could be useful for development of therapeutic inhibitors of hIAPP amyloid formation.

  18. An introduction to the dimer model

    International Nuclear Information System (INIS)

    Kenyon, R.

    2004-01-01

    A perfect matching of a graph is a subset of edges which covers every vertex exactly once, that is, for every vertex there is exactly one edge in the set with that vertex as endpoint. The dimer model is the study of the set of perfect matchings of a (possibly infinite) graph. The most well-known example is when the graph is Z 2 , for which perfect matchings are equivalent (via a simple duality) to domino tilings, that is, tilings of the plane with 2 x 1 and 1 x 2 rectangles. In the first three sections we study domino tilings of the plane and of finite polygonal regions, or equivalently, perfect matchings on Z 2 and subgraphs of Z 2 . In the last two sections we study the FK-percolation model and the dimer model on a more general family of planar graphs

  19. PT -symmetric dimer of coupled nonlinear oscillators

    Indian Academy of Sciences (India)

    In this case there are three solutions of the coupled dimer eqs (1) and (2) out of which we present two solutions now and the third one (a novel superposed solution) in the next subsection. Solution I: It is easy to check that u(t) = ±v(t) = Adn[β(t + t0), m]. (22) is an exact solution provided. (ǫ + δ)β2 = −2β2, (2 − m)β2 = −1 ± k.

  20. Electronic structure of the water dimer cation

    Czech Academy of Sciences Publication Activity Database

    Pieniazek, P. A.; Vande Vondele, J.; Jungwirth, Pavel; Krylov, A. I.; Bradforth, S. E.

    2008-01-01

    Roč. 112, č. 27 (2008), s. 6159-6170 ISSN 1089-5639 R&D Projects: GA ČR(CZ) GA202/06/0286 Grant - others:NSF(US) CHE-0617060 Institutional research plan: CEZ:AV0Z40550506 Keywords : water dimer * ionization * proton transfer * ab initio Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 2.871, year: 2008

  1. On the dimerization of linear polymers

    International Nuclear Information System (INIS)

    Aragao Carvalho, C. de.

    1988-08-01

    We use the continuum limit of the Su-Schrieffer-Heeger model for linear polymers to construct its effective potential (Gibbs free energy) both at zero and finite temperature. We study both trans and cis-polymers. Our results show that, depending on a renormalization condition to be extracted from experiment, there are several possibilities for the minima of the dimerized ground state of cis-polymers. All calculations are done in the one-loop approximation. (author). 16 refs, 3 figs

  2. Analgesic Activity of Some 1,2,4-Triazole Heterocycles Clubbed with Pyrazole, Tetrazole, Isoxazole and Pyrimidine

    OpenAIRE

    Gajanan Khanage, Shantaram; Raju, Appala; Baban Mohite, Popat; Bhanudas Pandhare, Ramdas

    2013-01-01

    Purpose: In the present study in vivo analgesic activity of some previously synthesized 1,2,4-triazole derivatives containing pyrazole, tetrazole, isoxazole and pyrimidine ring have been evaluated. Methods: Acetic acid induced writhing method and Hot plate method has been described to study analgesic activity of some 1,2,4-triazole derivatives containing pyrazole, tetrazole, isoxazole and pyrimidine as a pharmacological active lead. Results: Thirty six different derivatives con...

  3. Palmitoylated APP Forms Dimers, Cleaved by BACE1

    Science.gov (United States)

    Fenn, Rebecca H.; Barren, Cory; Tanzi, Rudolph E.; Kovacs, Dora M.

    2016-01-01

    A major rate-limiting step for Aβ generation and deposition in Alzheimer’s disease brains is BACE1-mediated cleavage (β-cleavage) of the amyloid precursor protein (APP). We previously reported that APP undergoes palmitoylation at two cysteine residues (Cys186 and Cys187) in the E1-ectodomain. 8–10% of total APP is palmitoylated in vitro and in vivo. Palmitoylated APP (palAPP) shows greater preference for β-cleavage than total APP in detergent resistant lipid rafts. Protein palmitoylation is known to promote protein dimerization. Since dimerization of APP at its E1-ectodomain results in elevated BACE1-mediated cleavage of APP, we have now investigated whether palmitoylation of APP affects its dimerization and whether this leads to elevated β-cleavage of the protein. Here we report that over 90% of palAPP is dimerized while only ~20% of total APP forms dimers. PalAPP-dimers are predominantly cis-oriented while total APP dimerizes in both cis- and trans-orientation. PalAPP forms dimers 4.5-times more efficiently than total APP. Overexpression of the palmitoylating enzymes DHHC7 and DHHC21 that increase palAPP levels and Aβ release, also increased APP dimerization in cells. Conversely, inhibition of APP palmitoylation by pharmacological inhibitors reduced APP-dimerization in coimmunoprecipitation and FLIM/FRET assays. Finally, in vitro BACE1-activity assays demonstrate that palmitoylation-dependent dimerization of APP promotes β-cleavage of APP in lipid-rich detergent resistant cell membranes (DRMs), when compared to total APP. Most importantly, generation of sAPPβ-sAPPβ dimers is dependent on APP-palmitoylation while total sAPPβ generation is not. Since BACE1 shows preference for palAPP dimers over total APP, palAPP dimers may serve as novel targets for effective β-cleavage inhibitors of APP as opposed to BACE1 inhibitors. PMID:27875558

  4. Antioxidant, DNA interaction, VEGFR2 kinase, topoisomerase I and in vitro cytotoxic activities of heteroleptic copper(II) complexes of tetrazolo[1,5-a]pyrimidines and diimines.

    Science.gov (United States)

    Haleel, A; Mahendiran, D; Veena, V; Sakthivel, N; Rahiman, A Kalilur

    2016-11-01

    A series of heteroleptic mononuclear copper(II) complexes of the type [Cu(L(1-3))(diimine)]ClO4 (1-6) containing three tetrazolo[1,5-a]pyrimidine core ligands, ethyl 5-methyl-7-(2-hydroxyphenyl)-4,7-dihydrotetrazolo[1,5-a]pyrimidine-6-carboxylate (HL(1)), ethyl 5-methyl-7-(4-diethylamino-2-hydroxyphenyl)-4,7-dihydrotetrazolo[1,5-a]pyrimidine-6-carboxylate (HL(2)) or ethyl 5-methyl-7-(2-hydroxy-4-nitrophenyl)-4,7-dihydrotetrazolo[1,5-a]pyrimidine-6-carboxylate (HL(3)), and two diimine coligands, 2,2'-bipyridyl (bpy) or 1,10-phenanthroline (phen) have been synthesized and characterized by spectral methods. The geometry of complexes have been determined with the help of electronic absorption and EPR splitting patterns, which suggest four coordinated square planar geometry around copper(II) ion. The lowering of HOMO-LUMO band gap value of complex 4 implies its higher biological activity compared to other complexes. Antioxidant studies revealed that the complexes possess considerable radical scavenging potency against DPPH. The binding studies of the complexes with calf thymus DNA (CT-DNA) revealed groove mode of binding, which was further supported by docking simulation. The complexes 3 and 4 strongly inhibit the topoisomerase I, and also strongly interact with VEGFR2 kinase receptor via π-π, σ-π and hydrogen bonding interaction. Gel electrophoresis experiments demonstrated the ability of the complexes to cleave plasmid DNA in the absence of activators. In vitro cytotoxic activities of the complexes were examined on three cancerous cell lines such as human lung (A549), cervical (HeLa) and colon (HCT-15), and two normal cells such as human embryonic kidney (HEK) and peripheral blood mononuclear cells (PBMCs). The live cell and fluorescent imaging of cancer cells were observed with acridine orange/ethidium bromide staining assay. All encouraging chemical and biological findings indicate that the complex 4 is a suitable candidate for drug target. Copyright © 2016

  5. Zero Field Splitting of the chalcogen diatomics using relativistic correlated wave-function methods

    DEFF Research Database (Denmark)

    Rota, Jean-Baptiste; Knecht, Stefan; Fleig, Timo

    2011-01-01

    The spectrum arising from the (π*)2 configuration of the chalcogen dimers, namely the X21, a2 and b0+ states, is calculated using Wave-Function Theory (WFT) based methods. Two-component (2c) and four-component (4c) MultiReference Configuration Interaction (MRCI) and Fock-Space Coupled Cluster (FS...... by a two-parameter model; Δε, the π* spinor splitting by spin-orbit coupling (SOC) and K, the exchange integral between the π*1 and the π*-1 spinors with respectively angular momenta 1 and −1. This model holds for all systems under study with the exception of Po2....

  6. MspA nanopores from subunit dimers.

    Directory of Open Access Journals (Sweden)

    Mikhail Pavlenok

    Full Text Available Mycobacterium smegmatis porin A (MspA forms an octameric channel and represents the founding member of a new family of pore proteins. Control of subunit stoichiometry is important to tailor MspA for nanotechnological applications. In this study, two MspA monomers were connected by linkers ranging from 17 to 62 amino acids in length. The oligomeric pore proteins were purified from M. smegmatis and were shown to form functional channels in lipid bilayer experiments. These results indicated that the peptide linkers did not prohibit correct folding and localization of MspA. However, expression levels were reduced by 10-fold compared to wild-type MspA. MspA is ideal for nanopore sequencing due to its unique pore geometry and its robustness. To assess the usefulness of MspA made from dimeric subunits for DNA sequencing, we linked two M1-MspA monomers, whose constriction zones were modified to enable DNA translocation. Lipid bilayer experiments demonstrated that this construct also formed functional channels. Voltage gating of MspA pores made from M1 monomers and M1-M1 dimers was identical indicating similar structural and dynamic channel properties. Glucose uptake in M. smegmatis cells lacking porins was restored by expressing the dimeric mspA M1 gene indicating correct folding and localization of M1-M1 pores in their native membrane. Single-stranded DNA hairpins produced identical ionic current blockades in pores made from monomers and subunit dimers demonstrating that M1-M1 pores are suitable for DNA sequencing. This study provides the proof of principle that production of single-chain MspA pores in M. smegmatis is feasible and paves the way for generating MspA pores with altered stoichiometries. Subunit dimers enable better control of the chemical and physical properties of the constriction zone of MspA. This approach will be valuable both in understanding transport across the outer membrane in mycobacteria and in tailoring MspA for nanopore

  7. Innovative wedge axe in making split firewood

    International Nuclear Information System (INIS)

    Mutikainen, A.

    1998-01-01

    Interteam Oy, a company located in Espoo, has developed a new method for making split firewood. The tools on which the patented System Logmatic are based are wedge axe and cylindrical splitting-carrying frame. The equipment costs about 495 FIM. The block of wood to be split is placed inside the upright carrying frame and split in a series of splitting actions using the innovative wedge axe. The finished split firewood remains in the carrying frame, which (as its name indicates) also serves as the means for carrying the firewood. This innovative wedge-axe method was compared with the conventional splitting of wood using an axe (Fiskars -handy 1400 splitting axe costing about 200 FIM) in a study conducted at TTS-Institute. There were eight test subjects involved in the study. In the case of the wedge-axe method, handling of the blocks to be split and of the finished firewood was a little quicker, but in actual splitting it was a little slower than the conventional axe method. The average productivity of splitting the wood and of the work stages related to it was about 0.4 m 3 per effective hour in both methods. The methods were also equivalent of one another in terms of the load imposed by the work when measured in terms of the heart rate. As regards work safety, the wedge-axe method was superior to the conventional method, but the continuous striking action and jolting transmitted to the arms were unpleasant (orig.)

  8. cis-Aquadichlorido[pyrimidin-2(1H-one-κN3]copper(II

    Directory of Open Access Journals (Sweden)

    A. Guy Orpen

    2008-07-01

    Full Text Available In the title compound, [CuCl2(C4H4N2O(H2O], the CuII cation is coordinated by two chloride anions, one pyrimidin-2-one N atom and one water molecule, giving a slightly distorted square-planar geometry. In the crystal structure, the pyrimidin-2-one rings stack along the b axis, with an interplanar distance of 3.306 Å, as do the copper coordination planes (interplanar spacing = 2.998 Å. The coordination around the Jahn–Teller-distorted CuII ion is completed by long Cu...O [3.014 (5 Å] and Cu...Cl [3.0194 (15 Å] interactions with adjacent molecules involved in this stacking. Several N—H...Cl, O—H...Cl and O—H...O intermolecular hydrogen bonds form a polar three-dimensional network.

  9. Studies on Synthesis of Some New Chalcone and Pyrimidines and their Antibacterial Activity

    Directory of Open Access Journals (Sweden)

    Ketan Mistry

    2005-01-01

    Full Text Available Pyrimidine-2-one derivatives, 2-[2-{1ʹ-(p-nitrophenyl-6ʹ-(substituted-phenyl-pyrimidine-2ʹ-one-4ʹ-yl}-hydrazinomethyl]-3-(p-methoxy phenyl-quina-zoline-4(3H-one [4a-j] have been synthesised by the condensation of p-nitro phenylurea and various chalcones, 2-(substituted phenylchalconylhydrazinomethyl-3-(p-methoxyphenyl-quinazoline-4(3H-one [3a-j] in the presence of catalytic amount of conc. HCl. And this series of chalcones have been synthesised by the reaction of 2-acetylhydrazinomethyl-3-(substitutedphenyl-quinazoline-4(3H-one [2] with different substituted aldehydes in presence of a 2% NaOH solution. These products have been characterized by means of elemental analysis, IR and NMR spectrul studies and tested for antibacterial activities against Staphylococcus aureus, Bacillus subtillis, Escherichia coli and Salmonella typhi.

  10. Synthesis and antiproliferative activity of imidazo[1,2-a]pyrimidine Mannich bases.

    Science.gov (United States)

    Aeluri, Raghunath; Alla, Manjula; Polepalli, Sowjanya; Jain, Nishant

    2015-07-15

    A series of imidazo[1,2-a]pyrimidine Mannich bases were designed, synthesized in two phases. Mannich bases were obtained by one pot three component condensation of imidazo[1,2-a]pyrimidine with secondary amine or piperazine and excess of formaldehyde solution in methanol. The synthesized Mannich bases were screened for in vitro growth inhibition against a panel of 3 different human cancer cell lines. Most of the synthesized compounds exhibited antiproliferative activity with GI50 values ranging from 0.01 to 79.4 μM. Compounds 5e, 6b and 7k were found to be effective inhibitors of growth of all cell lines, with GI50 values similar to that of standard drug. The structure and activity relationship has been disclosed. Copyright © 2015 Elsevier Masson SAS. All rights reserved.

  11. Ændring af pyrimidin metabolismen i laktokokker, Konstruktion af pyr-mutanter i L. lactis

    DEFF Research Database (Denmark)

    Hansen, Steen Lyders Lerche; Martinussen, Jan; Hammer, Karin

    1998-01-01

    korresponderende gener bliver kaldt carAB, pyrB, pyrC, pyrD (pyrDa og pyrDb/pyrK i L. lactis), pyrE, og pyrF (jvf. fig. 1).Der findes to pyrimidin-typer: Uracil (U) og Cytosin (C), samt derivater heraf. De eneste forbindelser mellem U- og C-pools er salvage-enzymet cytidin-deaminase (cdd), som katalyserer...... omdannelsen af cytidin til uridin og CTP syntetase (pyrG), der katalyserer omdannelsen af UTP til CTP (jvf. fig. 1). Ved kloning og mutagenese af primært pyrG, cdd og gener fra de novo syntesen er det muligt at konstruere stammer med ændrede pyrimidin pools, og undersøge betydningen for centrale fysiologiske...

  12. Chemotheraphy Efficiency of Phosphonium Heterocyclic Compounds with Pyrimidine Cycle in Models of Generalized Staph Infection

    Directory of Open Access Journals (Sweden)

    A.V. Humenna

    2016-02-01

    Full Text Available It was conducted the study of the effectiveness of chemotherapy with 2-phenyl-4-(1-pyrrolidinyl-6-izopropiltio-5-pyrimidyltriphenylphosphonium perchlorate, which refers to phosphonium heterocyclic compounds with pyrimidine cycle in the experiment on the model of generalized staph infection. The results were positive and they allow make a conclusion about the possibility of their use in clinical trials and develop promising antibacterial and antiseptic preparations on their basis.

  13. Dichloridobis[2-methyl-sulfanyl-4-(pyridin-2-yl)pyrimidine-κN,N]cobalt(II).

    Science.gov (United States)

    Yang, Wen-Na

    2011-09-01

    The asymmetric unit of the title compound, [CoCl(2)(C(10)H(9)N(3)S)(2)], contains one half-mol-ecule with the Co(II) atom situtated on a twofold rotational axis. The Co(II) atom, in an octa-hedral enviroment, is coordinated by four N atoms from two 2-methyl-sulfanyl-4-(pyridin-2-yl)pyrimidine ligands and two Cl atoms.

  14. How study patients who receive fluo pyrimidines to prevent ischemic events

    International Nuclear Information System (INIS)

    Saldombide, L.

    2010-01-01

    Introduction: Ischemic heart disease is the main cause of death in Uruguay and cancer is the second. The pillar of the systemic treatment of colorectal cancer are fluo pyrimidines and cause acute ischemic events in 3-8% of t rated patients. The 5 fluorouracil is the third anticancer drug most used Objective: Due to the high incidence of the two diseases and the risk of death caused by the ischemic treatment complications, the literature is analyzed to define how to study patients who receive fluo pyrimidines as a medium of preventing the same. Development: fluo pyrimidines cardio-toxicity can occur by myocardial toxicity, vasospasm, dihydropyrimidine dehydrogenase deficiency, autoimmune phenomena, platelet hyper aggregability, etc. The clinic is varied and underestimated: angina, abnormal ST silent and reversible, arrhythmias, heart failure, hypertension and heart failure. It is the most common complication with continuous infusion of 5 Fu and its equivalent capecitabine with bolus f lou pyrimidines. It is common that ischemic heart disease prioritises the risk increase of complications, but their absence does not exist. Without ischemic heart disease it is difficult to prevent ischemic events, however proposes that the older higher risk. Results: No uniform guidelines is advised: detailed history, determine if risk factors such as smoking, hypertension, diabetes and dyslipidemia and They are present electrocardiogram and cardiac evaluation. Warn the patient about angina l pain as early symptom and monitor symptoms during chemotherapy including cardio-vascular hypotension. Discontinue the medication and perform classic anti-angina l symptoms and / or signs of ischemia. Not reintroduce unless it is the only therapeutic option, since mortality may exceed

  15. Diversion of aspartate in ASS1-deficient tumours fosters de novo pyrimidine synthesis.

    Science.gov (United States)

    Rabinovich, Shiran; Adler, Lital; Yizhak, Keren; Sarver, Alona; Silberman, Alon; Agron, Shani; Stettner, Noa; Sun, Qin; Brandis, Alexander; Helbling, Daniel; Korman, Stanley; Itzkovitz, Shalev; Dimmock, David; Ulitsky, Igor; Nagamani, Sandesh Cs; Ruppin, Eytan; Erez, Ayelet

    2015-11-19

    Cancer cells hijack and remodel existing metabolic pathways for their benefit. Argininosuccinate synthase (ASS1) is a urea cycle enzyme that is essential in the conversion of nitrogen from ammonia and aspartate to urea. A decrease in nitrogen flux through ASS1 in the liver causes the urea cycle disorder citrullinaemia. In contrast to the well-studied consequences of loss of ASS1 activity on ureagenesis, the purpose of its somatic silencing in multiple cancers is largely unknown. Here we show that decreased activity of ASS1 in cancers supports proliferation by facilitating pyrimidine synthesis via CAD (carbamoyl-phosphate synthase 2, aspartate transcarbamylase, and dihydroorotase complex) activation. Our studies were initiated by delineating the consequences of loss of ASS1 activity in humans with two types of citrullinaemia. We find that in citrullinaemia type I (CTLN I), which is caused by deficiency of ASS1, there is increased pyrimidine synthesis and proliferation compared with citrullinaemia type II (CTLN II), in which there is decreased substrate availability for ASS1 caused by deficiency of the aspartate transporter citrin. Building on these results, we demonstrate that ASS1 deficiency in cancer increases cytosolic aspartate levels, which increases CAD activation by upregulating its substrate availability and by increasing its phosphorylation by S6K1 through the mammalian target of rapamycin (mTOR) pathway. Decreasing CAD activity by blocking citrin, the mTOR signalling, or pyrimidine synthesis decreases proliferation and thus may serve as a therapeutic strategy in multiple cancers where ASS1 is downregulated. Our results demonstrate that ASS1 downregulation is a novel mechanism supporting cancerous proliferation, and they provide a metabolic link between the urea cycle enzymes and pyrimidine synthesis.

  16. Pyrazolo[4,3-d]pyrimidines as new generation of cyclin-dependent kinase inhibitors

    Czech Academy of Sciences Publication Activity Database

    Moravcová, Daniela; Kryštof, Vladimír; Havlíček, Libor; Moravec, Jiří; Lenobel, René; Strnad, Miroslav

    2003-01-01

    Roč. 13, č. 18 (2003), s. 2989ů2992 ISSN 0960-894X R&D Projects: GA ČR GA303/02/0875; GA AV ČR KJB4038301 Institutional research plan: CEZ:AV0Z5038910 Keywords : Pyrazolo[4,3-d]pyrimidines * CDK1/ cyclin B * anticancer agents Subject RIV: EB - Genetics ; Molecular Biology Impact factor: 2.182, year: 2003

  17. Synthesis of pyrimidine containing nucleoside β-(R/S)-hydroxyphosphonate analogues

    OpenAIRE

    Meurillon, Maïa; Chaloin, Laurent; Peyrottes, Suzanne; Périgaud, Christian

    2011-01-01

    A concise route to nucleoside β-hydroxyphosphonate analogues is described. The use of a nucleoside β-ketophosphonate as the key intermediate allowed both the (R) and (S) isomers of β-hydroxyphosphonate analogues in the pyrimidine series to be accessed. Such derivatives may be considered as stable mimics of 5′-monophosphate nucleosides and, therefore, could be the starting point for the development of potential therapeutic agents.

  18. Radiation-induced DNA damage in halogenated pyrimidine incorporated cells and its correlation with radiosensitivity

    International Nuclear Information System (INIS)

    Watanabe, R.; Nikjoo, H.

    2003-01-01

    Cells with DNA containing 5-halogenated pyrimidines in place of thymidine show significant reductions of slope (Do) and shoulder (Dq) of their radiation survival curves. Similar radiosensitization has also been observed in the yield of DNA strand breaks. The purpose of this study is to obtain an insight into the mechanism of cell lethality by examining the relationship between the spectrum of DNA damage and the cell survival. In this study we estimated the enhancement of strand breaks due to incorporation of halogenated pyrimidine, the complexity of DNA damage and the probability of the initial DNA damage leading to cell inactivation. Monte Carlo track structure methods were used to model and simulate the induction of strand breakage by X-rays. The increase of DNA strand break was estimated by assuming the excess strand break was caused by the highly reactive uracil radicals at the halouracil substituted sites. The assumption of the enhancement mechanism of strand breaks was examined and verified by comparison with experimental data for induction of SSB and DSB. The calculated DNA damage spectrum shows the increase in complexity of strand breaks is due to incorporation of halogenated pyrimidines. The increase in the yield of DSB and cell lethality show similar trend at various degrees of halogenated pyrimidine substitution. We asked the question whether this agreement supports the hypothesis that DSB is responsible for cell lethality? The estimated number of lethal damage from the cell survival using a linear-quadratic model is much less than the initial yield of DSB. This work examines the correlation of cell lethality as a function of frequencies of complex form of double strand breaks

  19. Synthesis of some pyridine and pyrimidine derivatives via Michael-Addition

    International Nuclear Information System (INIS)

    El-Baih, Fatma E.M.; Al-Rasheed, Hessa H.; Al-Hazimi, Hassan M.

    2006-01-01

    Synthesis of pyridine and pyrimidine analogues 4 and 6-9 were achieved by Michael-addition of compounds containing either active methylene groups like, malononitrile , ethyl cyanoacetate and 1-tetralone or compounds containing active hydrogen atoms like, guanidine in the presence of an oxidizing agent and thiourea to 2-arylmethylidine-1-tetralone and 2-arylmethylidine-6-methoxy-1-tetralone (2) (enones). Addition of malononitrile in piperidine at room temperature to 2-amino-3-cyno-naphtho [1, 2-malonoitrile in sodium alkoxide or sodium hydroxide to 2 gave 4. Cyclization of 3a with acetic anhydride in the presence of conc. H2sO4 gave the naphtha-pyrano[2, 3-d]pyrimidin-8-one (5). Condensation of the pyrimidine thione derivatives 9 with chloroacetic acid gave the 3-oxobenzo[h]thiazoladino[2, 3-b]quinazoline derivatives (10), which were reacted through their active methylene groups with aromatic aldehydes to give the arylidine derivatives 11. These compounds were also prepared in one step by reacting 9 with chloroacetic acid and aromatic aldehydes. Condensation of 9 with 3-bromopropanoic acid gave 4-oxo-benzo[h]1, 3-thiazino[2, 3-b]quinazoline derivatives (12). The structures of the prepared compounds were mainly confirmed on the basis of spectroscopic methods. (author)

  20. Steroidal pyrimidines: Synthesis, characterization, molecular docking studies with DNA and in vitro cytotoxicity

    Science.gov (United States)

    Shamsuzzaman; Dar, Ayaz Mahmood; Yaseen, Zahid; Alam, Khursheed; Hussain, Altaf; Gatoo, Manzoor Ahmad

    2013-08-01

    A series of new steroid pyrimidines (7-9) were synthesized by reacting steroidal thiosemicarbazones (4-6) with diethyl malonate. The new compounds were characterized by IR, 1H NMR, 13C NMR, MS and analytical data. The interaction studies of compounds (7-9) with DNA were carried out by employing gel electrophoresis, UV-vis and fluorescence spectroscopy. The acting force between the compounds (7-9) and DNA was mainly hydrophobic while the other interactions like van der Waals, hydrogen bonding cannot be ruled out. The gel electrophoresis pattern also demonstrated that the compound 7 alone or in presence of Cu (II) causes the nicking of supercoiled pBR322 and it seems to follow the mechanistic pathway involving generation of hydroxyl radicals that are responsible for initiating DNA strand scission. The docking study of compounds (7-9) suggested that the intercalation of compounds in between the nucleotide base pairs might be due to the presence of pyrimidine moiety in steroid molecule. MTT assay was carried out to check the toxicity of new compounds (7-9) against the different human cancer as well as non-cancer cell lines A545, MCF-7, HeLa, HL-60, SW480, HepG2, HT-29, A549, 184B5, MCF10A, NL-20, HPC and HPLF. Apoptotic degradation of DNA in presence of steroidal pyrimidines (7-9) was analyzed by agarose gel electrophoresis and visualized by ethidium bromide staining (comet assay).

  1. Rim2, a pyrimidine nucleotide exchanger, is needed for iron utilization in mitochondria

    Science.gov (United States)

    Yoon, Heeyong; Zhang, Yan; Pain, Jayashree; Lyver, Elise R.; Lesuisse, Emmanuel; Pain, Debkumar; Dancis, Andrew

    2016-01-01

    Mitochondria transport and utilize iron for the synthesis of haem and Fe–S clusters. Although many proteins are known to be involved in these processes, additional proteins are likely to participate. To test this hypothesis, in the present study we used a genetic screen looking for yeast mutants that are synthetically lethal with the mitochondrial iron carriers Mrs3 and Mrs4. Several genes were identified, including an isolate mutated for Yfh1, the yeast frataxin homologue. All such triple mutants were complemented by increased expression of Rim2, another mitochondrial carrier protein. Rim2 overexpression was able to enhance haem and Fe–S cluster synthesis in wild-type or Δmrs3/Δmrs4 backgrounds. Conversely Rim2 depletion impaired haem and Fe–S cluster synthesis in wild-type or Δmrs3/Δmrs4 backgrounds, indicating a unique requirement for this mitochondrial transporter for these processes. Rim2 was previously shown to mediate pyrimidine exchange in and out of vesicles. In the present study we found that isolated mitochondria lacking Rim2 exhibited concordant iron defects and pyrimidine transport defects, although the connection between these two functions is not explained. When organellar membranes were ruptured to bypass iron transport, haem synthesis from added iron and porphyrin was still markedly deficient in Rim2-depleted mitochondrial lysate. The results indicate that Rim2 is a pyrimidine exchanger with an additional unique function in promoting mitochondrial iron utilization. PMID:21777202

  2. Intermediate energy cross sections for electron-impact vibrational-excitation of pyrimidine

    Energy Technology Data Exchange (ETDEWEB)

    Jones, D. B. [School of Chemical and Physical Sciences, Flinders University, GPO Box 2100, Adelaide, SA 5001 (Australia); Ellis-Gibbings, L.; García, G. [Instituto de Física Fundamental, CSIC, Serrano 113-bis, 28006 Madrid (Spain); Nixon, K. L. [Departamento de Física, Universidade Federal de Juiz de Fora, 36036-330 Juiz de Fora, Minas Gerais (Brazil); School of Biology, Chemistry and Forensic Science, University of Wolverhampton, Wolverhampton WV1 1LY (United Kingdom); Lopes, M. C. A. [Departamento de Física, Universidade Federal de Juiz de Fora, 36036-330 Juiz de Fora, Minas Gerais (Brazil); Brunger, M. J., E-mail: Michael.Brunger@flinders.edu.au [School of Chemical and Physical Sciences, Flinders University, GPO Box 2100, Adelaide, SA 5001 (Australia); Institute of Mathematical Sciences, University of Malaya, 50603 Kuala Lumpur (Malaysia)

    2015-09-07

    We report differential cross sections (DCSs) and integral cross sections (ICSs) for electron-impact vibrational-excitation of pyrimidine, at incident electron energies in the range 15–50 eV. The scattered electron angular range for the DCS measurements was 15°–90°. The measurements at the DCS-level are the first to be reported for vibrational-excitation in pyrimidine via electron impact, while for the ICS we extend the results from the only previous condensed-phase study [P. L. Levesque, M. Michaud, and L. Sanche, J. Chem. Phys. 122, 094701 (2005)], for electron energies ⩽12 eV, to higher energies. Interestingly, the trend in the magnitude of the lower energy condensed-phase ICSs is much smaller when compared to the corresponding gas phase results. As there is no evidence for the existence of any shape-resonances, in the available pyrimidine total cross sections [Baek et al., Phys. Rev. A 88, 032702 (2013); Fuss et al., ibid. 88, 042702 (2013)], between 10 and 20 eV, this mismatch in absolute magnitude between the condensed-phase and gas-phase ICSs might be indicative for collective-behaviour effects in the condensed-phase results.

  3. Pyrrolo[2,3-d]pyrimidines active as Btk inhibitors.

    Science.gov (United States)

    Musumeci, Francesca; Sanna, Monica; Greco, Chiara; Giacchello, Ilaria; Fallacara, Anna Lucia; Amato, Rosario; Schenone, Silvia

    2017-12-01

    Btk is a tyrosine kinase dysregulated in several B-cell malignancies and autoimmune diseases, and this has given rise to a search for Btk inhibitors. Nevertheless, only one Btk inhibitor, ibrutinib, has been approved to date, although other compounds are currently being evaluated in clinical trials or in preclinal stages. Area covered: This review, after a brief introduction on Btk and its inhibitors already in clinical trials, focusses on pyrrolo[2,3-d]pyrimidine derivatives patented in the last five years as Btk inhibitors. Indeed, the pyrrolo[2,3-d]pyrimidine scaffold, being a deaza-isostere of adenine, the nitrogenous base of ATP, is an actively pursued target for Btk inhibitors. The patent literature since 2012 have been extensively investigated, pointing out the general features of the patented compounds and, when it is possible, their mechanism of action. Expert opinion: The recently patented pyrrolo[2,3-d]pyrimidines, acting as reversible or irreversible inhibitors, showed a very interesting in vitro activity. For this reason, the development of compounds endowed with this scaffold could afford a significant impact in the search for drug candidates for the treatment of immune diseases or B-cell malignancies.

  4. Synthesis and fluorescence of new 3-biphenylpyrrolo[1,2-c]pyrimidines

    Directory of Open Access Journals (Sweden)

    Marian-Laurentiu Tatu

    2017-07-01

    Full Text Available New pyrrolo[1,2-c]pyrimidines derivates having a biphenyl moiety at position 3 have been synthesized by 1,3-dipolar cycloaddition of their corresponding N-ylides with activated alkynes. FTIR, 1H and 13C NMR spectroscopy and elemental analysis have been used to characterize the structures of the new nine pyrrolo[1,2-c]pyrimidine derivates. Absorption and fluorescence spectra have been recorded. The appropriate solvent for the photoluminescence properties of the studied compounds has been found to be chloroform:acetonitrile mixture (1:1. The main spectral features such as molar extinction coefficients (ε, Stokes shifts, quantum yields using quinine sulphate as standard, fluorescence quenching in the presence of benzoquinone and Stern-Volmer constants have been calculated. The substituent effects on intensity of absorption, maximum absorbance wavelengths and fluorescence parameters have been discussed. The highest quantum yield value was found for ethyl 3-(4-biphenylyl-7-(3,4-dimethoxybenzoylpyrrolo[1,2-c]pyrimidine-5-carboxylate (0.55. The obtained results suggest that the studied compounds are promising candidates for future study in order to evaluate their use in practical applications in fluorescent chemical sensors.

  5. Advancing viral RNA structure prediction: measuring the thermodynamics of pyrimidine-rich internal loops.

    Science.gov (United States)

    Phan, Andy; Mailey, Katherine; Saeki, Jessica; Gu, Xiaobo; Schroeder, Susan J

    2017-05-01

    Accurate thermodynamic parameters improve RNA structure predictions and thus accelerate understanding of RNA function and the identification of RNA drug binding sites. Many viral RNA structures, such as internal ribosome entry sites, have internal loops and bulges that are potential drug target sites. Current models used to predict internal loops are biased toward small, symmetric purine loops, and thus poorly predict asymmetric, pyrimidine-rich loops with >6 nucleotides (nt) that occur frequently in viral RNA. This article presents new thermodynamic data for 40 pyrimidine loops, many of which can form UU or protonated CC base pairs. Uracil and protonated cytosine base pairs stabilize asymmetric internal loops. Accurate prediction rules are presented that account for all thermodynamic measurements of RNA asymmetric internal loops. New loop initiation terms for loops with >6 nt are presented that do not follow previous assumptions that increasing asymmetry destabilizes loops. Since the last 2004 update, 126 new loops with asymmetry or sizes greater than 2 × 2 have been measured. These new measurements significantly deepen and diversify the thermodynamic database for RNA. These results will help better predict internal loops that are larger, pyrimidine-rich, and occur within viral structures such as internal ribosome entry sites. © 2017 Phan et al.; Published by Cold Spring Harbor Laboratory Press for the RNA Society.

  6. Parallel BLAST on split databases.

    Science.gov (United States)

    Mathog, David R

    2003-09-22

    BLAST programs often run on large SMP machines where multiple threads can work simultaneously and there is enough memory to cache the databases between program runs. A group of programs is described which allows comparable performance to be achieved with a Beowulf configuration in which no node has enough memory to cache a database but the cluster as an aggregate does. To achieve this result, databases are split into equal sized pieces and stored locally on each node. Each query is run on all nodes in parallel and the resultant BLAST output files from all nodes merged to yield the final output. Source code is available from ftp://saf.bio.caltech.edu/

  7. Manganese-based Materials Inspired by Photosynthesis for Water-Splitting

    Directory of Open Access Journals (Sweden)

    Harvey J.M. Hou

    2011-09-01

    Full Text Available In nature, the water-splitting reaction via photosynthesis driven by sunlight in plants, algae, and cyanobacteria stores the vast solar energy and provides vital oxygen to life on earth. The recent advances in elucidating the structures and functions of natural photosynthesis has provided firm framework and solid foundation in applying the knowledge to transform the carbon-based energy to renewable solar energy into our energy systems. In this review, inspired by photosynthesis robust photo water-splitting systems using manganese-containing materials including Mn-terpy dimer/titanium oxide, Mn-oxo tetramer/Nafion, and Mn-terpy oligomer/tungsten oxide, in solar fuel production are summarized and evaluated. Potential problems and future endeavors are also discussed.

  8. Dimeric assembly of enterocyte brush border enzymes

    DEFF Research Database (Denmark)

    Danielsen, E M

    1994-01-01

    The noncovalent, dimeric assembly of small intestinal brush border enzymes was studied by sedimentation analysis in density gradients of extracts of pulse-labeled pig jejunal mucosal explants. Like aminopeptidase N (EC 3.4.11.2), sucrase-isomaltase (EC 3.2.1.48-10), aminopeptidase A (EC 3...... appearance of the liposome-reconstituted enzyme [Norén et al. (1986) J. Biol. Chem. 261, 12306-12309], showing only the inner, membrane-anchored domains of the monomers to be in close contact with one another while the outer domains are far apart. In contrast to the other brush border enzymes studied...

  9. Dimerization and oligomerization of the chaperone calreticulin

    DEFF Research Database (Denmark)

    Jørgensen, Charlotte S; Ryder, L Rebekka; Steinø, Anne

    2003-01-01

    protein. Using PAGE, urea gradient gel electrophoresis, capillary electrophoresis and MS, we show that dimerization through the SH group can be induced by lowering the pH to 5-6, heating, or under conditions that favour partial unfolding such as urea concentrations above 2.6 m or SDS concentrations above...... that favour partial unfolding or an intramolecular local conformational change that allows oligomerization, resulting in a heterogeneous mixture of oligomers consisting of up to 10 calreticulin monomers. The oligomeric calreticulin was very stable, but oligomerization was partially reversed by addition of 8 m...

  10. Algebraic techniques for diagonalization of a split quaternion matrix in split quaternionic mechanics

    Energy Technology Data Exchange (ETDEWEB)

    Jiang, Tongsong, E-mail: jiangtongsong@sina.com [Department of Mathematics, Linyi University, Linyi, Shandong 276005 (China); Department of Mathematics, Heze University, Heze, Shandong 274015 (China); Jiang, Ziwu; Zhang, Zhaozhong [Department of Mathematics, Linyi University, Linyi, Shandong 276005 (China)

    2015-08-15

    In the study of the relation between complexified classical and non-Hermitian quantum mechanics, physicists found that there are links to quaternionic and split quaternionic mechanics, and this leads to the possibility of employing algebraic techniques of split quaternions to tackle some problems in complexified classical and quantum mechanics. This paper, by means of real representation of a split quaternion matrix, studies the problem of diagonalization of a split quaternion matrix and gives algebraic techniques for diagonalization of split quaternion matrices in split quaternionic mechanics.

  11. Kinetics of the dimerization of retroviral proteases: The "fireman's grip" and dimerization

    Czech Academy of Sciences Publication Activity Database

    Ingr, Marek; Kondrová, Taťána; Stříšovský, Kvido; Majerová, E.; Konvalinka, Jan

    2003-01-01

    Roč. 12, - (2003), s. 2173-2182 ISSN 0961-8368 R&D Projects: GA MZd NI6339 Institutional research plan: CEZ:AV0Z4055905 Keywords : retroviral protease * dimerization * HIV protease Subject RIV: CE - Biochemistry Impact factor: 3.787, year: 2003

  12. Tunneling anisotropic magnetoresistance via molecular π orbitals of Pb dimers

    Science.gov (United States)

    Schöneberg, Johannes; Ferriani, Paolo; Heinze, Stefan; Weismann, Alexander; Berndt, Richard

    2018-01-01

    Pb dimers on a ferromagnetic surface are shown to exhibit large tunneling anisotropic magnetoresistance (TAMR) due to molecular π orbitals. Dimers oriented differently with respect to the magnetization directions of a ferromagnetic Fe double layer on W(110) were made with a scanning tunneling microscope. Depending on the dimer orientations, TAMR is absent or as large as 20% at the Fermi level. General arguments and first-principles calculations show that mixing of molecular orbitals due to spin-orbit coupling, which leads to TAMR, is maximal when the magnetization is oriented parallel to the dimer axis.

  13. Synthesis and Antimicrobial Activity of Some New Pyrazole, Fused Pyrazolo[3,4-d]-pyrimidine and Pyrazolo[4,3-e][1,2,4]- triazolo[1,5-c]pyrimidine Derivatives

    Directory of Open Access Journals (Sweden)

    Omar A. Miqdad

    2008-07-01

    Full Text Available Hydrazonyl bromides 2a,b reacted with active methylene compounds (dibenzoylmethane, acetylacetone, ethyl acetoacetate, phenacyl cyanide, acetoacetanilide, ethyl cyanoacetate, cyanoacetamide and malononitrile to afford the corresponding 1,3,4,5- tetrasubstituted pyrazole derivatives 5-12a,b. Reaction of 12a,b with formamide, formic acid and triethyl orthoformate give the pyrazolo[3,4-d]pyrimidine, pyrazolo[3,4- d]pyrimidin-4(3Hone and 5-ethoxymethylene-aminopyrazole-4-carbo-nitrile derivatives 13-15a,b, respectively. Compounds 15a,b reacted with benzhydrazide and hydrazine hydrate to afford pyrazolo[4,3-e][1,2,4]triazolo[1,5-c]pyrimidine and [4-iminopyrazolo- [3,4-d]pyrimidin-5-yl]amine derivatives 16a,b and 17a,b. Reactions of compounds 17a,b with triethyl orthoformate and carbon disulfide give the corresponding pyrazolo[4,3-e]- [1,2,4]triazolo[1,5-c]pyrimidine derivatives 18a,b and 19a,b, respectively.

  14. Testing PVLAS axions with resonant photon splitting

    CERN Document Server

    Gabrielli, E; Gabrielli, Emidio; Giovannini, Massimo

    2007-01-01

    The photon splitting gamma -> gamma gamma in a time-independent and inhomogeneous magnetized background is considered when neutral and ultralight spin-0 particles are coupled to two-photons. Depending on the inhomogeneity scale of the external field, resonant photon splitting can occur. If an optical laser crosses a magnetic field of few Tesla with typical inhomogeneity scale of the order of the meter, a potentially observable rate of photon splittings is expected for the PVLAS range of couplings and masses.

  15. Additive operator-difference schemes splitting schemes

    CERN Document Server

    Vabishchevich, Petr N

    2013-01-01

    Applied mathematical modeling isconcerned with solving unsteady problems. This bookshows how toconstruct additive difference schemes to solve approximately unsteady multi-dimensional problems for PDEs. Two classes of schemes are highlighted: methods of splitting with respect to spatial variables (alternating direction methods) and schemes of splitting into physical processes. Also regionally additive schemes (domain decomposition methods)and unconditionally stable additive schemes of multi-component splitting are considered for evolutionary equations of first and second order as well as for sy

  16. Iterative Splitting Methods for Differential Equations

    CERN Document Server

    Geiser, Juergen

    2011-01-01

    Iterative Splitting Methods for Differential Equations explains how to solve evolution equations via novel iterative-based splitting methods that efficiently use computational and memory resources. It focuses on systems of parabolic and hyperbolic equations, including convection-diffusion-reaction equations, heat equations, and wave equations. In the theoretical part of the book, the author discusses the main theorems and results of the stability and consistency analysis for ordinary differential equations. He then presents extensions of the iterative splitting methods to partial differential

  17. Photoexcitation of iodide ion-pyrimidine clusters above the electron detachment threshold: Intracluster electron transfer versus nucleobase-centred excitations

    Science.gov (United States)

    Matthews, Edward; Cercola, Rosaria; Mensa-Bonsu, Golda; Neumark, Daniel M.; Dessent, Caroline E. H.

    2018-02-01

    Laser photodissociation spectroscopy of the I-.thymine (I-.T) and I-.cytosine (I-.C) nucleobase clusters has been conducted for the first time across the regions above the electron detachment thresholds to explore the excited states and photodissociation channels. Although photodepletion is strong, only weak ionic photofragment signals are observed, indicating that the clusters decay predominantly by electron detachment. The photodepletion spectra of the I-.T and I-.C clusters display a prominent dipole-bound excited state (I) in the vicinity of the vertical detachment energy (˜4.0 eV). Like the previously studied I-.uracil (I-.U) cluster [W. L. Li et al., J. Chem. Phys. 145, 044319 (2016)], the I-.T cluster also displays a second excited state (II) centred at 4.8 eV, which we similarly assign to a π-π* nucleobase-localized transition. However, no distinct higher-energy absorption bands are evident in the spectra of the I-.C. Time-dependent density functional theory (TDDFT) calculations are presented, showing that while each of the I-.T and I-.U clusters displays a single dominant π-π* nucleobase-localized transition, the corresponding π-π* nucleobase transitions for I-.C are split across three separate weaker electronic excitations. I- and deprotonated nucleobase anion photofragments are observed upon photoexcitation of both I-.U and I-.T, with the action spectra showing bands (at 4.0 and 4.8 eV) for both the I- and deprotonated nucleobase anion production. The photofragmentation behaviour of the I-.C cluster is distinctive as its I- photofragment displays a relatively flat profile above the expected vertical detachment energy. We discuss the observed photofragmentation profiles of the I-.pyrimidine clusters, in the context of the previous time-resolved measurements, and conclude that the observed photoexcitations are primarily consistent with intracluster electron transfer dominating in the near-threshold region, while nucleobase-centred excitations

  18. Spin Splitting in Different Semiconductor Quantum Wells

    International Nuclear Information System (INIS)

    Hao Yafei

    2012-01-01

    We theoretically investigate the spin splitting in four undoped asymmetric quantum wells in the absence of external electric field and magnetic field. The quantum well geometry dependence of spin splitting is studied with the Rashba and the Dresselhaus spin-orbit coupling included. The results show that the structure of quantum well plays an important role in spin splitting. The Rashba and the Dresselhaus spin splitting in four asymmetric quantum wells are quite different. The origin of the distinction is discussed in this work. (condensed matter: electronic structure, electrical, magnetic, and optical properties)

  19. Dark matter from split seesaw

    International Nuclear Information System (INIS)

    Kusenko, Alexander; Takahashi, Fuminobu; Yanagida, Tsutomu T.

    2010-01-01

    The seesaw mechanism in models with extra dimensions is shown to be generically consistent with a broad range of Majorana masses. The resulting democracy of scales implies that the seesaw mechanism can naturally explain the smallness of neutrino masses for an arbitrarily small right-handed neutrino mass. If the scales of the seesaw parameters are split, with two right-handed neutrinos at a high scale and one at a keV scale, one can explain the matter-antimatter asymmetry of the universe, as well as dark matter. The dark matter candidate, a sterile right-handed neutrino with mass of several keV, can account for the observed pulsar velocities and for the recent data from Chandra X-ray Observatory, which suggest the existence of a 5 keV sterile right-handed neutrino.

  20. Emittance compensation in split photoinjectors

    Directory of Open Access Journals (Sweden)

    Klaus Floettmann

    2017-01-01

    Full Text Available The compensation of correlated emittance contributions is of primary importance to optimize the performance of high brightness photoinjectors. While only extended numerical simulations can capture the complex beam dynamics of space-charge-dominated beams in sufficient detail to optimize a specific injector layout, simplified models are required to gain a deeper understanding of the involved dynamics, to guide the optimization procedure, and to interpret experimental results. In this paper, a slice envelope model for the emittance compensation process in a split photoinjector is presented. The emittance term is included in the analytical solution of the beam envelope in a drift, which is essential to take the emittance contribution due to a beam size mismatch into account. The appearance of two emittance minima in the drift is explained, and the matching into the booster cavity is discussed. A comparison with simulation results points out effects which are not treated in the envelope model, such as overfocusing and field nonlinearities.

  1. Gauge mediated mini-split

    Science.gov (United States)

    Cohen, Timothy; Craig, Nathaniel; Knapen, Simon

    2016-03-01

    We propose a simple model of split supersymmetry from gauge mediation. This model features gauginos that are parametrically a loop factor lighter than scalars, accommodates a Higgs boson mass of 125 GeV, and incorporates a simple solution to the μ- b μ problem. The gaugino mass suppression can be understood as resulting from collective symmetry breaking. Imposing collider bounds on μ and requiring viable electroweak symmetry breaking implies small a-terms and small tan β — the stop mass ranges from 105 to 108 GeV. In contrast with models with anomaly + gravity mediation (which also predict a one-loop loop suppression for gaugino masses), our gauge mediated scenario predicts aligned squark masses and a gravitino LSP. Gluinos, electroweakinos and Higgsinos can be accessible at the LHC and/or future colliders for a wide region of the allowed parameter space.

  2. Minimal Doubling and Point Splitting

    Energy Technology Data Exchange (ETDEWEB)

    Creutz, M.

    2010-06-14

    Minimally-doubled chiral fermions have the unusual property of a single local field creating two fermionic species. Spreading the field over hypercubes allows construction of combinations that isolate specific modes. Combining these fields into bilinears produces meson fields of specific quantum numbers. Minimally-doubled fermion actions present the possibility of fast simulations while maintaining one exact chiral symmetry. They do, however, introduce some peculiar aspects. An explicit breaking of hyper-cubic symmetry allows additional counter-terms to appear in the renormalization. While a single field creates two different species, spreading this field over nearby sites allows isolation of specific states and the construction of physical meson operators. Finally, lattice artifacts break isospin and give two of the three pseudoscalar mesons an additional contribution to their mass. Depending on the sign of this mass splitting, one can either have a traditional Goldstone pseudoscalar meson or a parity breaking Aoki-like phase.

  3. Gauge mediated mini-split

    Energy Technology Data Exchange (ETDEWEB)

    Cohen, Timothy [Institute of Theoretical Science, University of Oregon,Eugene, OR 97403 (United States); Craig, Nathaniel [Department of Physics, University of California,Santa Barbara, CA 93106 (United States); Knapen, Simon [Berkeley Center for Theoretical Physics,University of California, Berkeley, CA 94720 (United States); Theoretical Physics Group,Lawrence Berkeley National Laboratory, Berkeley, CA 94720 (United States)

    2016-03-15

    We propose a simple model of split supersymmetry from gauge mediation. This model features gauginos that are parametrically a loop factor lighter than scalars, accommodates a Higgs boson mass of 125 GeV, and incorporates a simple solution to the μ−b{sub μ} problem. The gaugino mass suppression can be understood as resulting from collective symmetry breaking. Imposing collider bounds on μ and requiring viable electroweak symmetry breaking implies small a-terms and small tan β — the stop mass ranges from 10{sup 5} to 10{sup 8} GeV. In contrast with models with anomaly + gravity mediation (which also predict a one-loop loop suppression for gaugino masses), our gauge mediated scenario predicts aligned squark masses and a gravitino LSP. Gluinos, electroweakinos and Higgsinos can be accessible at the LHC and/or future colliders for a wide region of the allowed parameter space.

  4. The role of dimerization in prion replication.

    Science.gov (United States)

    Tompa, Peter; Tusnády, Gábor E; Friedrich, Peter; Simon, István

    2002-04-01

    The central theme in prion diseases is the conformational transition of a cellular protein from a physiologic to a pathologic (so-called scrapie) state. Currently, two alternative models exist for the mechanism of this autocatalytic process; in the template assistance model the prion is assumed to be a monomer of the scrapie conformer, whereas in the nucleated polymerization model it is thought to be an amyloid rod. A recent variation on the latter assumes disulfide reshuffling as the mechanism of polymerization. The existence of stable dimers, let alone their mechanistic role, is not taken into account in either of these models. In this paper we review evidence supporting that the dimerization of either the normal or the scrapie state, or both, has a decisive role in prion replication. The contribution of redox changes, i.e., the temporary opening and possible rearrangement of the intramolecular disulfide bridge is also considered. We present a model including these features largely ignored so far and show that it adheres satisfactorily to the observed phenomenology of prion replication.

  5. Rotational Spectrum of Propargyl Alcohol Dimer

    Science.gov (United States)

    Mani, Devendra; Arunan, E.

    2013-06-01

    Propargyl alcohol is a molecule of interest to astrophysics as well as combustion studies. Rotational-tunneling spectra of propargyl alcohol monomer is well known and shows that the molecule exists in gauche form. Recently we reported microwave spectra of Ar...propargyl alcohol complex. Propargyl alcochol exists in gauche form in the complex as well. In this study we have recorded pure rotational spectra of propargyl alcohol dimer between 4-13 GHz range.A total of 47 transitions, 24 a-type, 16 b-type and 7 c-type, have been observed and fitted with semi rigid rotor asymmetric top hamiltonian. The fitted rotational constants are: A = 2321.83323(47) MHz, B = 1150.47726(24) MHz and C = 1124.89000(20) MHz. The standard deviation for the fit is 2.5 kHz. The experimental rotational constants are very close to the structure predicted by ab-initio calculations in which two gauche-propargyl alcohol moieties are in three point contact stabilized by O-H...O, O-H...pi and C-H...pi interactions. Few transitions for duterated isotopologues of the dimer have also been observed and search for the remaining transitions is in progress. Details will be presented in the talk. E. Hirota,J. Mol. Spectrosc. 26 (1968) 335-350. J.C. Pearson, B.J. Drouin, J. Mol. Spectrosc. 234 (2005) 149-156. D. Mani, E. Arunan, ChemPhysChem 14 (2013) 754-763.

  6. Critical importance of the de novo pyrimidine biosynthesis pathway for Trypanosoma cruzi growth in the mammalian host cell cytoplasm

    Energy Technology Data Exchange (ETDEWEB)

    Hashimoto, Muneaki, E-mail: muneaki@juntendo.ac.jp [Department of Molecular and Cellular Parasitology, Juntendo University School of Medicine, 2-1-1 Hongo, Bunkyo-ku, Tokyo 113-8421 (Japan); Morales, Jorge; Fukai, Yoshihisa; Suzuki, Shigeo; Takamiya, Shinzaburo; Tsubouchi, Akiko; Inoue, Syou [Department of Molecular and Cellular Parasitology, Juntendo University School of Medicine, 2-1-1 Hongo, Bunkyo-ku, Tokyo 113-8421 (Japan); Inoue, Masayuki [Graduate School of Pharmaceutical Sciences, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033 (Japan); Kita, Kiyoshi [Department of Biomedical Chemistry, Graduate School of Medicine, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033 (Japan); Harada, Shigeharu [Department of Applied Biology, Graduate School of Science and Technology, Kyoto Institute of Technology, Sakyo-ku, Kyoto 606-8585 (Japan); Tanaka, Akiko [Systems and Structural Biology Center, RIKEN, Tsurumi, Yokohama 230-0045 (Japan); Aoki, Takashi [Department of Molecular and Cellular Parasitology, Juntendo University School of Medicine, 2-1-1 Hongo, Bunkyo-ku, Tokyo 113-8421 (Japan); Nara, Takeshi, E-mail: tnara@juntendo.ac.jp [Department of Molecular and Cellular Parasitology, Juntendo University School of Medicine, 2-1-1 Hongo, Bunkyo-ku, Tokyo 113-8421 (Japan)

    2012-01-20

    Highlights: Black-Right-Pointing-Pointer We established Trypanosoma cruzi lacking the gene for carbamoyl phosphate synthetase II. Black-Right-Pointing-Pointer Disruption of the cpsII gene significantly reduced the growth of epimastigotes. Black-Right-Pointing-Pointer In particular, the CPSII-null mutant severely retarded intracellular growth. Black-Right-Pointing-Pointer The de novo pyrimidine pathway is critical for the parasite growth in the host cell. -- Abstract: The intracellular parasitic protist Trypanosoma cruzi is the causative agent of Chagas disease in Latin America. In general, pyrimidine nucleotides are supplied by both de novo biosynthesis and salvage pathways. While epimastigotes-an insect form-possess both activities, amastigotes-an intracellular replicating form of T. cruzi-are unable to mediate the uptake of pyrimidine. However, the requirement of de novo pyrimidine biosynthesis for parasite growth and survival has not yet been elucidated. Carbamoyl-phosphate synthetase II (CPSII) is the first and rate-limiting enzyme of the de novo biosynthetic pathway, and increased CPSII activity is associated with the rapid proliferation of tumor cells. In the present study, we showed that disruption of the T. cruzicpsII gene significantly reduced parasite growth. In particular, the growth of amastigotes lacking the cpsII gene was severely suppressed. Thus, the de novo pyrimidine pathway is important for proliferation of T. cruzi in the host cell cytoplasm and represents a promising target for chemotherapy against Chagas disease.

  7. Poly purine.pyrimidine sequences upstream of the beta-galactosidase gene affect gene expression in Saccharomyces cerevisiae

    Directory of Open Access Journals (Sweden)

    Brahmachari Samir K

    2001-10-01

    Full Text Available Abstract Background Poly purine.pyrimidine sequences have the potential to adopt intramolecular triplex structures and are overrepresented upstream of genes in eukaryotes. These sequences may regulate gene expression by modulating the interaction of transcription factors with DNA sequences upstream of genes. Results A poly purine.pyrimidine sequence with the potential to adopt an intramolecular triplex DNA structure was designed. The sequence was inserted within a nucleosome positioned upstream of the β-galactosidase gene in yeast, Saccharomyces cerevisiae, between the cycl promoter and gal 10Upstream Activating Sequences (UASg. Upon derepression with galactose, β-galactosidase gene expression is reduced 12-fold in cells carrying single copy poly purine.pyrimidine sequences. This reduction in expression is correlated with reduced transcription. Furthermore, we show that plasmids carrying a poly purine.pyrimidine sequence are not specifically lost from yeast cells. Conclusion We propose that a poly purine.pyrimidine sequence upstream of a gene affects transcription. Plasmids carrying this sequence are not specifically lost from cells and thus no additional effort is needed for the replication of these sequences in eukaryotic cells.

  8. HPLC analysis for the clinical-biochemical diagnosis of inborn errors of metabolism of purines and pyrimidines.

    Science.gov (United States)

    Lazzarino, Giuseppe; Amorini, Angela Maria; Di Pietro, Valentina; Tavazzi, Barbara

    2011-01-01

    The determination of purines and pyrimidines in biofluids is useful for the clinical-biochemical characterization of acute and chronic pathological states that induce transient or permanent alterations of metabolism. In particular, the diagnosis of several inborn errors of metabolism (IEMs) is accomplished by the analysis of circulating and excreted purines and pyrimidines. It is certainly advantageous to simultaneously determine the full purine and pyrimidine profile, as well as to quantify other compounds of relevance (e.g., organic acids, amino acids, sugars) in various metabolic hereditary diseases, in order to screen for a large number of IEMs using a reliable and sensitive analytical method characterized by mild to moderate costs. Toward this end, we have developed an ion-pairing HPLC method with diode array detection for the synchronous separation of several purines and pyrimidines. This method also allows the quantification of additional compounds such as N-acetylated amino acids and dicarboxylic acids, the concentrations of which are profoundly altered in different IEMs. The application of the method in the analysis of biological samples from patients with suspected purine and pyrimidine disorders is presented to illustrate its applicability for the clinical-biochemical diagnosis of IEM.

  9. The a-Type K = 0 Microwave Spectrum of the Methanol Dimer

    Science.gov (United States)

    Lovas, F. J.; Belov, S. P.; Tretyakov, M. Y.; Stahl, W.; Suenram, R. D.

    1995-04-01

    The rotational spectrum of (CH3OH)2 has been observed in the region 4-22 GHz with pulsed-beam Fabry-Perot cavity Fourier-transform microwave spectrometers at NIST and at the University of Kiel. Each a-type R(J), Ka = 0 transition is split into 15 states by tunneling motions for (CH3OH)2, (13CH3OH)2, (CH3OD)2, (CD3OH)2, and (CD3OH)2. The preliminary analysis of the methyl internal rotation presented here was guided by the previously developed multidimensional tunneling theory which predicts 16 tunneling components for each R(J) transition from 25 distinct tunneling motions. Several isotopically mixed dimers of methanol have also been measured, namely 13CH3OH, CH3OD, CD3OH, and CD3OD bound to 12CH3OH. Since the hydrogen bond interchange motion (which converts a donor into an acceptor) would produce a new and less favorable conformation from an energy viewpoint, it does not occur and only 10 tunneling components are observed for these mixed dimers. The structure of the complex is similar to that of water dimer with a hydrogen bond distance of 2.035 Å and a tilt of the acceptor methanol of 84° from the O-H-O axis. The effective barrier to internal rotation for the donor methyl group of (CH3OH)2 is ν3 = 183.0 cm-1 and is one-half of the value for the methanol monomer (370 cm-1), while the barrier to internal rotation of the acceptor methyl group is 120 cm-1.

  10. SplitDist—Calculating Split-Distances for Sets of Trees

    DEFF Research Database (Denmark)

    Mailund, T

    2004-01-01

    We present a tool for comparing a set of input trees, calculating for each pair of trees the split-distances, i.e., the number of splits in one tree not present in the other.......We present a tool for comparing a set of input trees, calculating for each pair of trees the split-distances, i.e., the number of splits in one tree not present in the other....

  11. Microwave measurements of the tropolone–formic acid doubly hydrogen bonded dimer

    Energy Technology Data Exchange (ETDEWEB)

    Pejlovas, Aaron M.; Kukolich, Stephen G. [Department of Chemistry and Biochemistry, University of Arizona, Tucson, Arizona 85721 (United States); Serrato, Agapito; Lin, Wei [Department of Chemistry, University of Texas Rio Grande Valley, Brownsville, Texas 78520 (United States)

    2016-01-28

    The microwave spectrum was measured for the doubly hydrogen bonded dimer formed between tropolone and formic acid. The predicted symmetry of this dimer was C{sub 2v}(M), and it was expected that the concerted proton tunneling motion would be observed. After measuring 25 a- and b-type rotational transitions, no splittings which could be associated with a concerted double proton tunneling motion were observed. The calculated barrier to the proton tunneling motion is near 15 000 cm{sup −1}, which would likely make the tunneling frequencies too small to observe in the microwave spectra. The rotational and centrifugal distortion constants determined from the measured transitions were A = 2180.7186(98) MHz, B = 470.873 90(25) MHz, C = 387.689 84(22) MHz, D{sub J} = 0.0100(14) kHz, D{sub JK} = 0.102(28) kHz, and D{sub K} = 13.2(81) kHz. The B3LYP/aug-cc-pVTZ calculated rotational constants were within 1% of the experimentally determined values.

  12. Studies on Synthesis of Some Novel Heterocyclic Chalcone, Pyrazoline, Pyrimidine - 2 - One, Pyrimidine - 2 - Thione, para-Acetanilide Sulphonyl and Benzoyl Derivatives and their Antimicrobial Activity

    Directory of Open Access Journals (Sweden)

    Rakesh N. Mistry

    2005-01-01

    Full Text Available 1, 2 - Dichloro benzene on chlorosulphonation by chlorosulphonic acid gives 1, 2 - [dichloro] - benzene sulphonyl chloride which on condensation with p –amino acetophenone gives 1-[acetyl] - 1’ , 2’ - [dichloro] - dibenz sulphonamide derivative. This derivative undergo condensation with 2,4- dichloro benzaldehyde gives 1- [3” - (sub. phenyl - 2” - propene - 1” - one] - 1’ , 2’ - [dichloro] - dibenz sulphonamide derivative which on reaction with 99% hydrazine hydrate and glacial acetic acid gives 1-[acetyl]-3- [1’ , 2’ - (dichloro - dibenz sulphonamide] -5 - [2” , 4” - dichloro phenyl] - 2 - pyrazoline derivative. This derivative reacts with various substituted aldehydes to give corresponding substituted chalcone derivatives [1(a-j]. Now, these chalcone derivatives [1(a-j] on condensation with urea gives corresponding substituted pyrimidine - 2 - one derivatives [2(a-j] and on condensation with thio-urea gives corresponding substituted pyrimidine- 2 -thione derivatives [3(a-j]. Further, these chalcone derivatives [1(a-j] on reaction with 99% hydrazine hydrate gives 1 - [1’ - (H - 5’ - (sub. phenyl - 2’ - pyrazoline]- 3 - [1” , 2” - (dichloro - dibenz sulphonamide] - 5 - [2’’’ , 4’’’ - dichloro phenyl]-2- pyrazoline derivatives [4(a-j] as an intermediate compounds, which on condensation with p-acetanilide sulphonyl chloride gives corresponding substituted p - acetanilide sulphonyl derivatives [5(a-j] and on condensation with benzoyl chloride gives corresponding substituted benzoyl derivatives [6(a-j]. Structure elucidation of synthesised compounds has been made on the basis of elemental analysis, I.R. spectral studies and 1H N.M.R. spectral studies. The antimicrobial activity of the synthesised compounds has been studied against the cultures “Staphylococcus aureus”, “Escherichia coli” and “Candela albicans”.

  13. Heteroaromatization with 4-Hydroxycoumarin Part II: Synthesis of Some New Pyrano[2,3-d]pyrimidines, [1,2,4]triazolo[1,5-c]pyrimidines and Pyrimido[1,6-b]-[1,2,4]triazine Derivatives

    Directory of Open Access Journals (Sweden)

    A. H. Bedair

    2001-05-01

    Full Text Available A variety of novel [1,2,4]triazolo[1,5-c]pyrimidine-13-ones (4a-f and (5b-d could be obtained via reaction of 9-amino-7-(4’-chlorophenyl-8,9-dihydro-8-imino-6H,7H-[1]benzopyrano[3`,4`:5,6]pyrano[2,3-d]pyrimidine-6-one (3 with a variety of reagents. Pyrano[2,3-d]pyrimidine-6-ones 5a, 8a-c and pyrimido[1,6-b][1,2,4]-triazine-3,14-dione (6 were also prepared. The antimicrobial activity of some of the synthesized compounds was tested.

  14. Stochastic optimization-based study of dimerization kinetics

    Indian Academy of Sciences (India)

    Abstract. We investigate the potential of numerical algorithms to decipher the kinetic parameters involved in multi-step chemical reactions. To this end, we study dimerization kinetics of protein as a model system. We follow the dimerization kinetics using a stochastic simulation algorithm and combine it with three different.

  15. Exact Solution of a Generalized Nonlinear Schrodinger Equation Dimer

    DEFF Research Database (Denmark)

    Christiansen, Peter Leth; Maniadis, P.; Tsironis, G.P.

    1998-01-01

    We present exact solutions for a nonlinear dimer system defined throught a discrete nonlinear Schrodinger equation that contains also an integrable Ablowitz-Ladik term. The solutions are obtained throught a transformation that maps the dimer into a double Sine-Gordon like ordinary nonlinear...

  16. Two Populations Mean-Field Monomer-Dimer Model

    Science.gov (United States)

    Alberici, Diego; Mingione, Emanuele

    2018-04-01

    A two populations mean-field monomer-dimer model including both hard-core and attractive interactions between dimers is considered. The pressure density in the thermodynamic limit is proved to satisfy a variational principle. A detailed analysis is made in the limit of one population is much smaller than the other and a ferromagnetic mean-field phase transition is found.

  17. Split Questionnaire Design for Massive Surveys

    NARCIS (Netherlands)

    Adiguzel, F.; Wedel, M.

    2008-01-01

    Companies are conducting more and longer surveys than ever before. Massive questionnaires are pervasive in marketing practice. As an alternative to the heuristic methods that are currently used to split questionnaires, this study develops a methodology to design the split questionnaire in a way that

  18. Cheating More when the Spoils Are Split

    Science.gov (United States)

    Wiltermuth, Scott S.

    2011-01-01

    Four experiments demonstrated that people are more likely to cheat when the benefits of doing so are split with another person, even an anonymous stranger, than when the actor alone captures all of the benefits. In three of the studies, splitting the benefits of over-reporting one's performance on a task made such over-reporting seem less…

  19. Standard Model Particles from Split Octonions

    Directory of Open Access Journals (Sweden)

    Gogberashvili M.

    2016-01-01

    Full Text Available We model physical signals using elements of the algebra of split octonions over the field of real numbers. Elementary particles are corresponded to the special elements of the algebra that nullify octonionic norms (zero divisors. It is shown that the standard model particle spectrum naturally follows from the classification of the independent primitive zero divisors of split octonions.

  20. Split Scheduling with Uniform Setup Times

    NARCIS (Netherlands)

    Schalekamp, F.; Sitters, R.A.; van der Ster, S.L.; Stougie, L.; Verdugo, V.; van Zuylen, A.

    2015-01-01

    We study a scheduling problem in which jobs may be split into parts, where the parts of a split job may be processed simultaneously on more than one machine. Each part of a job requires a setup time, however, on the machine where the job part is processed. During setup, a machine cannot process or

  1. Split scheduling with uniform setup times.

    NARCIS (Netherlands)

    F. Schalekamp; R.A. Sitters (René); S.L. van der Ster; L. Stougie (Leen); V. Verdugo; A. van Zuylen

    2015-01-01

    htmlabstractWe study a scheduling problem in which jobs may be split into parts, where the parts of a split job may be processed simultaneously on more than one machine. Each part of a job requires a setup time, however, on the machine where the job part is processed. During setup, a

  2. On split Lie triple systems II

    Indian Academy of Sciences (India)

    Lie triple system with a coherent 0-root space is the direct sum of the family of its minimal ideals, each one being a simple split Lie triple system, and the simplicity of T is characterized. In the present paper we extend these results to arbitrary split Lie triple systems with no restrictions on their 0-root spaces. Keywords.

  3. Defects in pyrimidine degradation identified by HPLC-electrospray tandem mass spectrometry of urine specimens or urine-soaked filter paper strips

    NARCIS (Netherlands)

    van Lenthe, H.; van Kuilenburg, A. B.; Ito, T.; Bootsma, A. H.; van Cruchten, A.; Wada, Y.; van Gennip, A. H.

    2000-01-01

    Urinary concentrations of thymine, uracil, and their degradation products are useful indicators of deficiencies of enzymes of the pyrimidine degradation pathway. We describe a rapid, specific method to measure these concentrations to detect inborn errors of pyrimidine metabolism. We used urine or

  4. The growth rate of pyrimidine auxotrophic mutants of Lactococcus lactis MG1363 is reduced in the presence of exogenous aspartate

    DEFF Research Database (Denmark)

    Hansen, Steen Lyders Lerche; Martinussen, Jan

    1998-01-01

    Nucleotide metabolism is important for all cells as supplier of building blocks for the synthesis of nucleic acids and coenzymes. Furthermore, they act as intracellular energy carriers and allosteric effectors in a large number of enzymatic reactions. Nucleotides can either be made de novo or from...... preformed metabolites present in the growth medium. In addition to the obvious phenotype of a mutant in the pyrimidine biosynthetic pathway - requirement for a pyrimidine precursor in the growth medium - pleiotrophic effects are often seen. The work presented here shows, that a mutation in one of the genes...... encoding enzymes in the distal part of the pyrimidine biosynthetic pathway of L. lactis MG1363, results in reduction of the growth rate if exogenous aspartate is supplied to the growth medium. This observation can be explained by an increased accumulation of a toxic intermediate, most likely carbamoyl...

  5. Palladium dimers adsorbed on graphene: A DFT study

    International Nuclear Information System (INIS)

    Kaur, Gagandeep; Gupta, Shuchi; Dharamvir, Keya

    2015-01-01

    The 2D structure of graphene shows a great promise for enhanced catalytic activity when adsorbed with palladium. We performed a systematic density functional theory (DFT) study of the adsorption of palladium dimer (Pd 2 ) on graphene using SIESTA package, in the generalized gradient approximation (GGA). The adsorption energy, geometry, and charge transfer of Pd 2 -graphene system are calculated. Both horizontal and vertical orientations of Pd 2 on graphene are studied. Our calculations revealed that the minimum energy configuration for Pd dimer is parallel to the graphene sheet with its two atoms occupying centre of adjacent hexagonal rings of graphene sheet. Magnetic moment is induced for Pd dimer adsorbed on graphene in vertical orientation while horizontal orientation of Pd dimer on graphene do not exhibit magnetism. Insignificant energy differences among adsorption sites means that dimer mobility on the graphene sheet is high. There is imperceptible distortion of graphene sheet perpendicular to its plane. However, some lateral displacements are seen

  6. Metal membrane with dimer slots as a universal polarizer

    DEFF Research Database (Denmark)

    Zhukovsky, Sergei; Zalkovskij, Maksim; Malureanu, Radu

    2014-01-01

    for the electromagnetic response of an arbitrary dimer based on the Green functions approach. The theory confirms that a great variety of polarization properties, such as birefringence, chirality and elliptical dichroism, can be achieved in a metal layer with such slot-dimer patterning (i.e. in a metasurface). Optical......In this work, we show theoretically and confirm experimentally that thin metal membranes patterned with an array of slot dimers (or their Babinet analogue with metal rods) can function as a versatile spectral and polarization filter. We present a detailed covariant multipole theory...... properties of the metasurface can be extensively tuned by varying the geometry (shape and dimensions) of the dimer, for example, by adjusting the sizes and mutual placement of the slots (e.g. inter-slot distance and alignment angle). Three basic shapes of dimers are analyzed: II-shaped (parallel slots), V...

  7. Family C 7TM receptor dimerization and activation

    DEFF Research Database (Denmark)

    Bonde, Marie Mi; Sheikh, Søren P; Hansen, Jakob Lerche

    2006-01-01

    The family C seven transmembrane (7TM) receptors constitutes a small and especially well characterized subfamily of the large 7TM receptor superfamily. Approximately 50% of current prescription drugs target 7TM receptors, this biologically important family represents the largest class of drug......-targets today. It is well established that family C 7TM receptors form homo- or hetero-dimers on the cell surface of living cells. The large extra-cellular domains (ECD) have been crystallized as a dimer in the presence and absence of agonist. Upon agonist binding, the dimeric ECD undergoes large conformational...... changes that lead to receptor activation. Despite extensive studies of the receptor transmembrane domain, several key features, including the exact organization of the complete receptor dimer, the sequence of events leading to receptor activation, and the functional significance of dimerization, have yet...

  8. Particulate photocatalysts for overall water splitting

    Science.gov (United States)

    Chen, Shanshan; Takata, Tsuyoshi; Domen, Kazunari

    2017-10-01

    The conversion of solar energy to chemical energy is a promising way of generating renewable energy. Hydrogen production by means of water splitting over semiconductor photocatalysts is a simple, cost-effective approach to large-scale solar hydrogen synthesis. Since the discovery of the Honda-Fujishima effect, considerable progress has been made in this field, and numerous photocatalytic materials and water-splitting systems have been developed. In this Review, we summarize existing water-splitting systems based on particulate photocatalysts, focusing on the main components: light-harvesting semiconductors and co-catalysts. The essential design principles of the materials employed for overall water-splitting systems based on one-step and two-step photoexcitation are also discussed, concentrating on three elementary processes: photoabsorption, charge transfer and surface catalytic reactions. Finally, we outline challenges and potential advances associated with solar water splitting by particulate photocatalysts for future commercial applications.

  9. 4-metalated condensed pyrimidines: their preparation and reaction with aldehydes under Barbier-type conditions.

    Science.gov (United States)

    Therkelsen, Frans D; Rottländer, Mario; Thorup, Niels; Pedersen, Erik Bjerregaard

    2004-06-10

    [reaction: see text] The organometallic intermediate obtained from halogen-metal exchanges of 4-iodo-6-phenylthieno[2,3-d]pyrimidine under Barbier-type conditions was reacted with aldehydes to form the corresponding alcohols in moderate yields. The reaction involving an organolithium intermediate proceeded only at low temperature, whereas the reaction involving a magnesium ate intermediate also proceeded at room temperature. A crystal structure confirms that the expected constitutional alcohol isomer is formed, where no migration has taken place. The conditions were also suitable for 9-benzyl-6-iodopurine.

  10. Low-energy electron scattering from pyrimidine: Similarities and differences with benzene

    Science.gov (United States)

    Jones, D. B.; Bellm, S. M.; Limão-Vieira, P.; Brunger, M. J.

    2012-05-01

    Differential cross sections for low-energy electron-impact excitation of the unresolved combinations of 23B2 + 21A1 and 31A1 + 21B2 electronic states of pyrimidine are reported. Comparisons are made with recent differential cross section measurements for the electron-impact excitation of the 1E1u and unresolved 1B1u + 3E2g electronic states of benzene [H. Kato, M. Hoshino, H. Tanaka, P. Limão-Vieira, O. Ingolfsson, L. Campbell, M.J. Brunger, J. Chem. Phys. 134 (2011) 134308.], in order to evaluate the nature of electron impact π-π∗ transitions in aromatic species.

  11. Temperature dependence of desoxyribosylation of pyrimidine derivatives labelled with carbon-14 and tritium

    International Nuclear Information System (INIS)

    Pritasil, L.; Filip, J.

    1977-01-01

    The effect of the temperature and concentration of the enzyme preparation from Escherichia coli B on the reaction of pyrimidine bases with 2-desoxy-α-D-riboso-l-phosphate or α-D-riboso-l-phosphate was studied. It was found that at +2 deg C and low enzyme concentration higher yields of nucleosides are obtained than at the commonly used temperature of 37 deg C. The reaction time, however, must be protracted. The prepared [2- 14 C] uridine, 2'-deoxy[2- 14 C] uridine and [2- 14 C] thymidine had a high specific activity and radiochemical purity

  12. Dimer Coverings on Random Polyomino Chains

    Science.gov (United States)

    Xiao, Chuanqi; Chen, Haiyan

    2015-06-01

    A polyomino chain is a planar square lattice that can be constructed by successively attaching squares to the previous one in two possible ways. A random polyomino chain is then generated by incorporating the Bernoulli distribution to the two types of attachment, which describes a zeroth-order Markov process. Let (ℜn, p) be the ensemble of random polyomino chains with n squares, where p∈[0,1] is a constant. Then, in this paper, we determine the explicit expression for the expectation of the number of dimer coverings over (ℜn, p). Our result shows that, with only one exception, i.e., p = 0, the average of the logarithm of this expectation is asymptotically nonzero when n → ∞.

  13. Dualism of Sensitivity and Selectivity of Porphyrin Dimers in Electroanalysis.

    Science.gov (United States)

    Lisak, Grzegorz; Tamaki, Takashi; Ogawa, Takuji

    2017-04-04

    This work uncovers the application of porphyrin dimers for the use in electroanalysis, such as potentiometric determination of ions. It also puts in question a current perception of an occurrence of the super-Nernstian response, as a result of the possible dimerization of single porphyrins within an ion-selective membrane. To study that, four various porphyrin dimers were used as ionophores, namely, freebase-freebase, Zn-Zn, Zn-freebase, and freebase-Zn. Since the Zn-freebase and freebase-Zn porphyrin dimers carried both anion- and cation-sensitive porphyrin units, their application in ISEs was utilized in both anion- and cation-sensitive sensors. With respect to the lipophilic salt added, both porphyrins dimers were found anion- and cation-sensitive. This allowed using a single molecule as novel type of versatile ionophore (anion- and cation-selective), simply by varying the membrane composition. All anion-sensitive sensors were perchlorate-sensitive, while the cation-selective sensors were silver-sensitive. The selectivity of the sensors depended primarily on the porphyrin dimers in the ion-selective membrane. Furthermore, the selectivity of cation-sensitive dimer based sensors was found significantly superior to the ones measured for the single porphyrin unit based sensors (precursors of the porphyrin dimers). Thus, the dimerization of single porphyrins may actually be a factor to increase or modulate porphyrin selectivity. Moreover, in the case of cation-sensitive sensors, the selectivity vastly depended on the order of porphyrin units in the dimer. This opens a new approach of regulating and adjusting sensitivity and selectivity of the sensor through the application of complex porphyrin systems with more than one porphyrin units with mix sensitive porphyrins.

  14. Efficient isolation of major procyanidin A-type dimers from peanut skins and B-type dimers from grape seeds

    NARCIS (Netherlands)

    Appeldoorn, M.M.; Sanders, M.B.; Vincken, J.P.; Cheynier, V.; Guerneve, Le C.; Gruppen, H.

    2009-01-01

    In order to fully explore the biofunctional potential of proanthocyanidins (PA), isolated and well-characterised PA dimers are of great importance. Current methods to obtain pure A- and B-type dimers are laborious, because they comprise multiple chromatographic steps, often yielding only one or two

  15. Disulfide Bonds within the C2 Domain of RAGE Play Key Roles in Its Dimerization and Biogenesis

    Science.gov (United States)

    Wei, Wen; Lampe, Leonie; Park, Sungha; Vangara, Bhavana S.; Waldo, Geoffrey S.; Cabantous, Stephanie; Subaran, Sarah S.; Yang, Dongmei; Lakatta, Edward G.; Lin, Li

    2012-01-01

    Background The receptor for advanced glycation end products (RAGE) on the cell surface transmits inflammatory signals. A member of the immunoglobulin superfamily, RAGE possesses the V, C1, and C2 ectodomains that collectively constitute the receptor's extracellular structure. However, the molecular mechanism of RAGE biogenesis remains unclear, impeding efforts to control RAGE signaling through cellular regulation. Methodology and Result We used co-immunoprecipitation and crossing-linking to study RAGE oligomerization and found that RAGE forms dimer-based oligomers. Via non-reducing SDS-polyacrylamide gel electrophoresis and mutagenesis, we found that cysteines 259 and 301 within the C2 domain form intermolecular disulfide bonds. Using a modified tripartite split GFP complementation strategy and confocal microscopy, we also found that RAGE dimerization occurs in the endoplasmic reticulum (ER), and that RAGE mutant molecules without the double disulfide bridges are unstable, and are subjected to the ER-associated degradation. Conclusion Disulfide bond-mediated RAGE dimerization in the ER is the critical step of RAGE biogenesis. Without formation of intermolecular disulfide bonds in the C2 region, RAGE fails to reach cell surface. Significance This is the first report of RAGE intermolecular disulfide bond. PMID:23284645

  16. Tandem Aldol-Michael Reactions in Aqueous Diethylamine Medium: A Greener and Efficient Approach to Bis-Pyrimidine Derivatives

    Directory of Open Access Journals (Sweden)

    Abdullah M. Al-Majid

    2013-12-01

    Full Text Available A simple protocol, involving the green synthesis for the construction of novel bis-pyrimidine derivatives, 3a–i and 4a–e are accomplished by the aqueous diethylamine media promoted tandem Aldol-Michael reaction between two molecules of barbituric acid derivatives 1a,b with various aldehydes. This efficient synthetic protocol using an economic and environmentally friendly reaction media with versatility and shorter reaction time provides bis-pyrimidine derivatives with high yields (88%–99%.

  17. Stretches of alternating pyrimidine/purines and purines are respectively linked with pathogenicity and growth temperature in prokaryotes

    DEFF Research Database (Denmark)

    Ussery, David; Bohlin, J; Hardy, SP

    2009-01-01

    BACKGROUND: The genomic fractions of purine (RR) and alternating pyrimidine/purine (YR) stretches of 10 base pairs or more, have been linked to genomic AT content, the formation of different DNA helices, strand-biased gene distribution, DNA structure, and more. Although some of these factors...... are a consequence of the chemical properties of purines and pyrimidines, a thorough statistical examination of the distributions of YR/RR stretches in sequenced prokaryotic chromosomes has to the best of our knowledge, not been undertaken. The aim of this study is to expand upon previous research by using...

  18. TD-DFT Investigation of the Magnetic Circular Dichroism Spectra of Some Purine and Pyrimidine Bases of Nucleic Acids

    DEFF Research Database (Denmark)

    Fahleson, Tobias; Kauczor, Joanna; Norman, Patrick

    2015-01-01

    We present a computational study of the magnetic circular dichroism (MCD) spectra in the 200–300 nm wavelength region of purine and its derivative hypoxanthine, as well as of the pyrimidine bases of nucleic acids uracil, thymine, and cytosine, using the B3LYP and CAM–B3LYP functionals. Solvent...... and the B term shape of the spectra of pyrimidine bases are reproduced. Our calculations also correctly reproduce the reversed phase of the MCD bands in purine compared to that of its derivatives present in nucleic acids. Solvent effects are sizable and system specific, but they do not in general alter...

  19. Synthesis and biological evaluation of new pyrazolo[3,4-d]pyrimidine derivatives

    Directory of Open Access Journals (Sweden)

    Asma Agrebi

    2014-05-01

    Full Text Available Several new pyrazolopyrimidine compounds were achieved from aminocyanopyarazole 1. The starting material 1 was initially coupled with orthoester at refluxed with various primary amines, ammonia, hydrazines and hydroxylamine to furnish a series of pyrazolo[3,4-d]pyrimidines. The reaction of imidate 2a-b with hydrazide derivatives led to the formation of pyrazolo[3,4-d][1,2,4]triazolo[4,3-c]pyrimidines. Some of the synthesized compounds 3a and 4c were evaluated for their anti-inflammatory, antipyretic and nociceptive activities. We start by studing the toxicity of these two molecules by measuring the corresponding DL50. The DL50 of 3a and 4c are estimated to 1333.2mg / kg and 1593.5mg / kg respectively. Pharmacological evaluation showed that compounds 3a and 4c at doses (5.5-22.2 mg / Kg, i.p exhibited anti-inflammatory activities compared to Ibuprofen (150 mg / Kg, i.p, used as a refer ence drug. Further, our study showed that the injection of derived pyrazolopyrimidines on hyperthermic animal leads to a decrease in temperature after 1 hours of treatment compared to paracetamol used as reference. In addition, the injection of derived pyrazolopyrimidines at different doses contains a potent nociceptive activity. This effect is dose-dependent compared to aspirin.

  20. Synthesis and antibacterial activities of novel pleuromutilin derivatives with a substituted pyrimidine moiety.

    Science.gov (United States)

    Yi, Yunpeng; Xu, Ximing; Liu, Yu; Xu, Shuijin; Huang, Xin; Liang, Jianping; Shang, Ruofeng

    2017-01-27

    The alarming growth of multidrug-resistant bacteria such as methicillin-resistant Staphylococcus aureus (MRSA) and vancomycin-resistant Enterococci (VRE) has become a major global health hazard. Therefore, urgent demand for new antibiotics with a unique mechanism of action is very necessary. The present study reports the design, synthesis, and antibacterial studies of a series of novel pleuromutilin derivatives with substituted 6-amino pyrimidine moieties. Most of the tested compounds exhibited highly potent anti-MRSA or Staphylococcus aureus (S. aureus) activities. 14-O-[(4,6-Diamino -pyrimidine-2-yl) thioacetyl] mutilin (3) and 14-O-[(2-((3R)-3-Hydroxymethylpiperidine-1-yl)-acetamido-6-aminopyrimidine-2-yl) thioacetyl] mutilin (5h) were the most active compounds and showed higher antibacterial activities. Compound 3 displayed rapid bactericidal activity and affected bacterial growth with the same manner as tiamulin fumarate. Docking experiments for compounds 3 and 5h carried out on the peptidyl transferase center (PTC) of 23S rRNA provided the information about the binding model. In vivo mouse systemic infection experimental results confirmed the therapeutic efficacy of compound 3, with ED 50 of 4.22 mg/kg body weight against MRSA. Copyright © 2016 Elsevier Masson SAS. All rights reserved.

  1. OCLI-023, a Novel Pyrimidine Compound, Suppresses Osteoclastogenesis In Vitro and Alveolar Bone Resorption In Vivo.

    Directory of Open Access Journals (Sweden)

    Hye Jung Ihn

    Full Text Available An abnormal increase in osteoclast differentiation and activation results in various bone-resorptive diseases, including periodontitis, rheumatoid arthritis, and osteoporosis. Chemical compounds containing pyrimidine ring have been shown to regulate a variety of biological processes. Therefore, in order to identify an antiresorptive agent, we synthesized a series of pyrimidine ring-containing chemical compounds, and found that OCLI-023 suppressed the differentiation and activation of osteoclasts in vitro. OCLI-023 directly inhibited receptor activator of nuclear factor-κB ligand (RANKL-induced differentiation of bone marrow macrophages into osteoclasts, without a cytotoxic response. OCLI-023 also downregulated the RANKL-induced mRNA expression of osteoclast markers as well as inhibited the formation of actin rings and resorption pits. OCLI-023 attenuated the RANKL-induced activation of c-Jun N-terminal kinase and nuclear factor kappa-light-chain-enhancer of activated B cell signaling pathways. In a mouse model of periodontitis, ligature induced an increase of distance between cementoenamel junction (CEJ and alveolar bone crest (ABC in the second molar, and OCLI-023 significantly reduced it. Histological analysis showed ligature-induced increase of osteoclast numbers was also significantly reduced by OCLI-023. These data demonstrated the inhibitory effect of OCLI-023 on osteoclast differentiation and activity of osteoclasts in vitro, as well as on ligature-induced bone loss in vivo, and OCLI-023 can be proposed as a novel anti-resorptive compound.

  2. Electronic absorption study on hydration, solvation behavior for some keto and thioketo pyrimidine derivatives.

    Science.gov (United States)

    Kılıç, H

    2013-03-01

    In this study, the hydration and solvation properties of recently synthesized 5-benzoyl-1-(methylphenylmethyleneamino)-4-phenyl-1H-pyrimidine-2-one, (I) and 5-benzoyl-1-(methylphenylmethyleneamino)-4-phenyl-1H-pyrimidine-2-thione, (II), were studied with respect to pH and time by using UV-vis spectroscopy method in aqueous (95.0% v/v water) and methanol (95.0% v/v methanol) media. The roles of the keto oxygen of I and the thioketo sulfur of II on the hydration and solvation behavior were discussed. The experiments were performed at 25 °C and at pH values between 1.0 and 13.0. Compound I was found to undergo hydration best in strongly acidic solutions. However, compound II was found to undergo solvation best in basic solutions. The preferred hydration and solvation mechanisms were discussed based on UV-vis data and the related mechanisms undergoing in strongly acidic and basic regions were proposed for the each compound. Copyright © 2012 Elsevier B.V. All rights reserved.

  3. Split-coil-system SULTAN

    International Nuclear Information System (INIS)

    Vecsey, G.

    1992-08-01

    The high field superconductor test facility SULTAN started operation successfully in May 1992. Originally designed for testing full scale conductors for the large magnets of the next generation fusion reactors, the SULTAN facility installed at PSI (Switzerland) was designed as a common venture of three European Laboratories: ENEA (Italy), ECN (Netherlands) and PSI, and built by ENEA and PSI in the framework of the Euratom Fusion Technology Program. Presently the largest facility in the world, with its superconducting split coil system generating 11 Tesla in a 0.6 m bore, it is ready now for testing superconductor samples with currents up to 50 kA at variable cooling conditions. Similar tests can be arranged also for other applications. SULTAN is offered by the European Community as a contribution to the worldwide cooperation for the next step of fusion reactor development ITER. First measurements on conductor developed by CEA (Cadarache) are now in progress. Others like those of ENEA and CERN will follow. For 1993, a test of an Italian 12 TZ model coil for fusion application is planned. SULTAN is a worldwide unique facility marking the competitive presence of Swiss technology in the field of applied superconductivity research. Based on development and design of PSI, the high field Nb 3 Sn superconductors and coils were fabricated at the works of Kabelwerke Brugg and ABB, numerous Swiss companies contributed to the success of this international effort. Financing of the Swiss contribution of SULTAN was made available by NEFF, BEW, BBW, PSI and EURATOM. (author) figs., tabs., 20 refs

  4. Advances in Chemistry and Pharmacology of Triterpenoid Synthetic Dimers.

    Science.gov (United States)

    Bednarczyk-Cwynar, Barbara; Günther, Andrzej

    2017-01-01

    This review focuses on advances in chemistry and pharmacology of synthetic triterpenoid dimers, obtained from natural compounds. Synthetic triterpenoid dimers are divided into specific subgroups based on the structure of main triterpenoid monomeric skeleton. Synthetic triterpenoid derivatives of dimeric structure can be obtained through the covalent linkage of the C-3 hydroxyl or another group, via the C-2 atom or the C-17 carboxyl group (mainly anhydrides, amides or esters). Some triterpenes can undergo chemical transformations leading to the formation of cyclic dimers or other types of dimers. Most of the obtained triterpenoid dimers have been subjected to pharmacological tests evaluating their biological activity, mainly antiviral (HIV-1 RT, HCVpp, VSVpp, HIV-RT-C8166-CCR5), cytotoxic (against e.g. 388, MCF-7, SF-268, NCIH460, KM20L2, DU-145, Hep-G2, A549, BGC-823, PC-3), anti-inflammatory (iNOS, RAW 264.7) and antidiabetic (RMGPa inhibition). The authors also reported the ability of some of the obtained cyclic triterpenoid dimers to recognize anions and to form self-assembled structures. Copyright© Bentham Science Publishers; For any queries, please email at epub@benthamscience.org.

  5. Asymmetric monometallic nanorod nanoparticle dimer and related compositions and methods

    KAUST Repository

    Han, Yu

    2016-03-31

    The fabrication of asymmetric monometallic nanocrystals with novel properties for plasmonics, nanophotonics and nanoelectronics. Asymmetric monometallic plasmonic nanocrystals are of both fundamental synthetic challenge and practical significance. In an example, a thiol-ligand mediated growth strategy that enables the synthesis of unprecedented Au Nanorod-Au Nanoparticle (AuNR-AuNP) dimers from pre-synthesized AuNR seeds. Using high-resolution electron microscopy and tomography, crystal structure and three-dimensional morphology of the dimer, as well as the growth pathway of the AuNP on the AuNR seed, was investigated for this example. The dimer exhibits an extraordinary broadband optical extinction spectrum spanning the UV, visible, and near infrared regions (300 - 1300 nm). This unexpected property makes the AuNR-AuNP dimer example useful for many nanophotonic applications. In two experiments, the dimer example was tested as a surface- enhanced Raman scattering (SERS) substrate and a solar light harvester for photothermal conversion, in comparison with the mixture of AuNR and AuNP. In the SERS experiment, the dimer example showed an enhancement factor about 10 times higher than that of the mixture, when the excitation wavelength (660 nm) was off the two surface plasmon resonance (SPR) bands of the mixture. In the photothermal conversion experiment under simulated sunlight illumination, the dimer example exhibited an energy conversion efficiency about 1.4 times as high as that of the mixture.

  6. 2-Photon tandem device for water splitting

    DEFF Research Database (Denmark)

    Seger, Brian; Castelli, Ivano Eligio; Vesborg, Peter Christian Kjærgaard

    2014-01-01

    Within the field Of photocatalytic water splitting there are several strategies to achieve the goal of efficient and cheap photocatalytic water splitting. This work examines one particular strategy by focusing on monolithically stacked, two-photon photoelectrochemical cells. The overall aim...... absorption, this is the more difficult side to optimize. Nevertheless, by using TiO2 as a transparent cathode protection layer in conjunction with known H-2 evolution catalysts, protection is clearly feasible for a large bandgap photocathode. This suggests that there may be promising strategies...... for photocatalytic water splitting by using a large bandgap photocathode and a low bandgap photoanode with attached protection layers....

  7. Communication: Tunnelling splitting in the phosphine molecule

    Energy Technology Data Exchange (ETDEWEB)

    Sousa-Silva, Clara; Tennyson, Jonathan; Yurchenko, Sergey N. [Department of Physics and Astronomy, University College London, London WC1E 6BT (United Kingdom)

    2016-09-07

    Splitting due to tunnelling via the potential energy barrier has played a significant role in the study of molecular spectra since the early days of spectroscopy. The observation of the ammonia doublet led to attempts to find a phosphine analogous, but these have so far failed due to its considerably higher barrier. Full dimensional, variational nuclear motion calculations are used to predict splittings as a function of excitation energy. Simulated spectra suggest that such splittings should be observable in the near infrared via overtones of the ν{sub 2} bending mode starting with 4ν{sub 2}.

  8. Splitting Functions at High Transverse Momentum

    CERN Document Server

    Moutafis, Rhea Penelope; CERN. Geneva. TH Department

    2017-01-01

    Among the production channels of the Higgs boson one contribution could become significant at high transverse momentum which is the radiation of a Higgs boson from another particle. This note focuses on the calculation of splitting functions and cross sections of such processes. The calculation is first carried out on the example $e\\rightarrow e\\gamma$ to illustrate the way splitting functions are calculated. Then the splitting function of $e\\rightarrow eh$ is calculated in similar fashion. This procedure can easily be generalized to processes such as $q\\rightarrow qh$ or $g\\rightarrow gh$.

  9. Vison excitations in near-critical quantum dimer models

    Science.gov (United States)

    Strübi, G.; Ivanov, D. A.

    2011-06-01

    We study vison excitations in a quantum dimer model interpolating between the Rokhsar-Kivelson models on the square and triangular lattices. In the square-lattice case, the model is known to be critical and characterized by U(1) topological quantum numbers. Introducing diagonal dimers brings the model to a Z2 resonating-valence-bond phase. We study variationally the emergence of vison excitations at low concentration of diagonal dimers, close to the critical point. We find that, in this regime, vison excitations are large in size and their structure resembles vortices in type-II superconductors.

  10. Family C 7TM receptor dimerization and activation

    DEFF Research Database (Denmark)

    Bonde, Marie Mi; Sheikh, Søren P; Hansen, Jakob Lerche

    2006-01-01

    changes that lead to receptor activation. Despite extensive studies of the receptor transmembrane domain, several key features, including the exact organization of the complete receptor dimer, the sequence of events leading to receptor activation, and the functional significance of dimerization, have yet...... to be fully defined. This review presents the biochemical support for family C 7TM receptor dimerization and discusses its importance for receptor biosynthesis, surface expression, ligand binding and activation, since lessons learnt here may well be applicable to the whole superfamily of 7TM receptors....

  11. Glycine transporter dimers: evidence for occurrence in the plasma membrane

    DEFF Research Database (Denmark)

    Bartholomäus, Ingo; Milan-Lobo, Laura; Nicke, Annette

    2008-01-01

    by fluorescence resonance energy transfer microscopy. Endoglycosidase treatment and surface biotinylation further revealed that complex-glycosylated GlyTs form dimers located at the cell surface. Furthermore, substitution of tryptophan 469 of GlyT2 by an arginine generated a transporter deficient in dimerization......Different Na(+)/Cl(-)-dependent neurotransmitter transporters of the SLC6a family have been shown to form dimers or oligomers in both intracellular compartments and at the cell surface. In contrast, the glycine transporters (GlyTs) GlyT1 and -2 have been reported to exist as monomers in the plasma...

  12. Subsurface dimerization in III-V semiconductor (001) surfaces

    DEFF Research Database (Denmark)

    Kumpf, C.; Marks, L.D.; Ellis, D.

    2001-01-01

    We present the atomic structure of the c(8 X 2) reconstructions of InSb-, InAs-, and GaAs-(001) surfaces as determined by surface x-ray diffraction using direct methods. Contrary to common belief, group III dimers are not prominent on the surface, instead subsurface dimerization of group m atoms...... takes place in the second bilayer, accompanied by a major rearrangement of the surface atoms above the dimers to form linear arrays. By varying the occupancies of four surface sites the (001)-c(8 X 2) reconstructions of III-V semiconductors can be described in a unified model....

  13. Photoelectron Spectroscopy of 4-Bromochlorobenzene Dimer and Trimer Anions

    International Nuclear Information System (INIS)

    Kim, Namdoo

    2013-01-01

    I investigated the electron attachment to 4-BCB dimer and trimer anions using anion photoelectron spectroscopy and theoretical calculations. I found that an excess electron can be delocalized to these clusters through extended π-network. However, the nature of the ion core is different for the dimer and trimer. For the heterodimer anions, the geometry is determined by the differences in electronegativity of the molecules. Dimer anions with a large electronegativity difference have T-shaped geometries and those with a small electronegativity difference have PD geometries

  14. 4-(Prop-2-yn-1-ylsulfanyl-1H-pyrazolo[3,4-d]pyrimidine

    Directory of Open Access Journals (Sweden)

    Mohamed El Hafi

    2017-10-01

    Full Text Available The asymmetric unit of the title compound, C8H6N4S, consists of two independent molecules differing in the orientation of the side chain. In the crystal, molecules form dimers through N—H...N hydrogen bonds. The dimers stack along the a-axis direction with weak π–π stacking interactions [centroid–centroid distances of 3.898 (2 and 3.908 (2 Å]. The crystal studied was refined as a two-component twin.

  15. Splitting Strip Detector Clusters in Dense Environments

    CERN Document Server

    Nachman, Benjamin Philip; The ATLAS collaboration

    2018-01-01

    Tracking in high density environments, particularly in high energy jets, plays an important role in many physics analyses at the LHC. In such environments, there is significant degradation of track reconstruction performance. Between runs 1 and 2, ATLAS implemented an algorithm that splits pixel clusters originating from multiple charged particles, using charge information, resulting in the recovery of much of the lost efficiency. However, no attempt was made in prior work to split merged clusters in the Semi Conductor Tracker (SCT), which does not measure charge information. In spite of the lack of charge information in SCT, a cluster-splitting algorithm has been developed in this work. It is based primarily on the difference between the observed cluster width and the expected cluster width, which is derived from track incidence angle. The performance of this algorithm is found to be competitive with the existing pixel cluster splitting based on track information.

  16. Structural basis of photosynthetic water-splitting

    International Nuclear Information System (INIS)

    Photosynthetic water-splitting takes place in photosystem II (PSII), a membrane protein complex consisting of 20 subunits with an overall molecular mass of 350 kDa. The light-induced water-splitting reaction catalyzed by PSII not only converts light energy into biologically useful chemical energy, but also provides us with oxygen indispensible for sustaining oxygenic life on the earth. We have solved the structure of PSII at a 1.9 Å resolution, from which, the detailed structure of the Mn 4 CaO 5 -cluster, the catalytic center for water-splitting, became clear. Based on the structure of PSII at the atomic resolution, possible mechanism of light-induced water-splitting was discussed

  17. Irrational beliefs, attitudes about competition, and splitting.

    Science.gov (United States)

    Watson, P J; Morris, R J; Miller, L

    2001-03-01

    Rational-Emotive Behavior Therapy (REBT) theoretically promotes actualization of both individualistic and social-oriented potentials. In a test of this assumption, the Belief Scale and subscales from the Survey of Personal Beliefs served as measures of what REBT presumes to be pathogenic irrationalities. These measures were correlated with the Hypercompetitive Attitude Scale (HCAS), the Personal Development Competitive Attitude Scale (PDCAS), factors from the Splitting Index, and self-esteem. Results for the HCAS and Self-Splitting supported the REBT claim about individualistic self-actualization. Mostly nonsignificant and a few counterintuitive linkages were observed for irrational beliefs with the PDCAS, Family-Splitting, and Other-Splitting, and these data suggested that REBT may be less successful in capturing the "rationality" of a social-oriented self-actualization. Copyright 2001 John Wiley & Sons, Inc.

  18. Consortium analysis of gene and gene-folate interactions in purine and pyrimidine metabolism pathways with ovarian carcinoma risk

    NARCIS (Netherlands)

    Kelemen, L.E.; Terry, K.L.; Goodman, M.T.; Webb, P.M.; Bandera, E.V.; McGuire, V.; Rossing, M.A.; Wang, Q.; Dicks, E.; Tyrer, J.P.; Song, H.; Kupryjanczyk, J.; Dansonka-Mieszkowska, A.; Plisiecka-Halasa, J.; Timorek, A.; Menon, U.; Gentry-Maharaj, A.; Gayther, S.A.; Ramus, S.J.; Narod, S.A.; Risch, H.A.; McLaughlin, J.R.; Siddiqui, N.; Glasspool, R.; Paul, J.; Carty, K.; Gronwald, J.; Lubinski, J.; Jakubowska, A.; Cybulski, C.; Kiemeney, L.A.L.M.; Massuger, L.F.A.G.; Altena, A.M. van; Aben, K.K.H.; Olson, S.H.; Orlow, I.; Cramer, D.W; Levine, D.A.; Bisogna, M.; Giles, G.G.; Southey, M.C.; Bruinsma, F.; Kjaer, S.K.; Hogdall, E.; Jensen, A.; Hogdall, C.K.; Lundvall, L.; Engelholm, S.A.; Heitz, F.; Bois, A. du; Harter, P.; Schwaab, I.; Butzow, R.; Nevanlinna, H.; Pelttari, L.M.; Leminen, A.; Thompson, P.J.; Lurie, G.; Wilkens, L.R.; Lambrechts, D.; Nieuwenhuysen, E. Van; Lambrechts, S.; Vergote, I.; Beesley, J.; Investigators, A.S.G.A.; Fasching, P.A.; Beckmann, M.W.; Hein, A.; Ekici, A.B.; Doherty, J.A.; Wu, A.H.; Pearce, C.L.; Pike, M.C.; Stram, D.; Chang-Claude, J.; Rudolph, A.; Dork, T.; Durst, M.; Hillemanns, P.; Runnebaum, I.B.; Bogdanova, N.; Antonenkova, N.; Odunsi, K.; Edwards, R.P.; Kelley, J.L.; Modugno, F.; Ness, R.B.; Karlan, B.Y.; Walsh, C.; Lester, J.; Orsulic, S.; Fridley, B.L.; Vierkant, R.A.; Cunningham, J.M.; Wu, X.; Lu, K.; Liang, D.; Hildebrandt, M.A.T.; Weber, R.P.; Iversen, E.S.

    2014-01-01

    SCOPE: We reevaluated previously reported associations between variants in pathways of one-carbon (1-C) (folate) transfer genes and ovarian carcinoma (OC) risk, and in related pathways of purine and pyrimidine metabolism, and assessed interactions with folate intake. METHODS AND Results : Odds

  19. The role of pyrimidine and water as underlying molecular constituents for describing radiation damage in living tissue: A comparative study

    Energy Technology Data Exchange (ETDEWEB)

    Fuss, M. C.; Ellis-Gibbings, L. [Instituto de Física Fundamental, Consejo Superior de Investigaciones Científicas (CSIC), Serrano 113-bis, 28006 Madrid (Spain); Jones, D. B. [School of Chemical and Physical Sciences, Flinders University, GPO Box 2100, Adelaide, South Australia 5001 (Australia); Brunger, M. J. [School of Chemical and Physical Sciences, Flinders University, GPO Box 2100, Adelaide, South Australia 5001 (Australia); Institute of Mathematical Sciences, University of Malaya, 50603 Kuala Lumpur (Malaysia); Blanco, F. [Departamento de Física Atómica, Molecular y Nuclear, Universidad Complutense de Madrid, Avenida Complutense, 28040 Madrid (Spain); Muñoz, A. [Centro de Investigaciones Energéticas Medioambientales y Tecnológicas, Avenida Complutense 22, 28040 Madrid (Spain); Limão-Vieira, P. [School of Chemical and Physical Sciences, Flinders University, GPO Box 2100, Adelaide, South Australia 5001 (Australia); Laboratório de Colisões Atómicas e Moleculares, CEFITEC, Departamento de Física, Faculdade de Ciências e Tecnologia, Universidade Nova de Lisboa, 2829-516 Caparica (Portugal); García, G., E-mail: g.garcia@csic.es [Instituto de Física Fundamental, Consejo Superior de Investigaciones Científicas (CSIC), Serrano 113-bis, 28006 Madrid (Spain); Centre for Medical Radiation Physics, University of Wollongong, Wollongong, NSW 2522 (Australia)

    2015-06-07

    Water is often used as the medium for characterizing the effects of radiation on living tissue. However, in this study, charged-particle track simulations are employed to quantify the induced physicochemical and potential biological implications when a primary ionising particle with energy 10 keV strikes a medium made up entirely of water or pyrimidine. Note that pyrimidine was chosen as the DNA/RNA bases cytosine, thymine, and uracil can be considered pyrimidine derivatives. This study aims to assess the influence of the choice of medium on the charged-particle transport, and identify how appropriate it is to use water as the default medium to describe the effects of ionising radiation on living tissue. Based on the respective electron interaction cross sections, we provide a model, which allows the study of radiation effects not only in terms of energy deposition (absorbed dose and stopping power) but also in terms of the number of induced molecular processes. Results of these parameters for water and pyrimidine are presented and compared.

  20. Synthesis and structure-activity relationship studies of polysubstituted pyrimidines as inhibitors of immune-activated nitric oxide production

    Czech Academy of Sciences Publication Activity Database

    Jansa, Petr; Holý, Antonín; Dračínský, Martin; Kolman, Viktor; Janeba, Zlatko; Kmoníčková, Eva; Zídek, Zdeněk

    2015-01-01

    Roč. 24, č. 5 (2015), s. 2154-2166 ISSN 1054-2523 R&D Projects: GA ČR(CZ) GAP303/12/0172; GA MV VG20102015046 Institutional support: RVO:61388963 ; RVO:68378041 Keywords : pyrimidine * nitric oxide * NO * anti-inflammatory Subject RIV: CC - Organic Chemistry Impact factor: 1.436, year: 2015

  1. Study of hydrogen mobility by hydrogen-deuterium exchange. II. Theoretical kinetic study in alkyl and amino-alkyl pyrimidines

    International Nuclear Information System (INIS)

    Pompon, Alain

    1975-01-01

    Alkyl groups bound to the pyrimidine ring can be deuterium substituted on the carbon adjacent to the ring, in acidic D 2 O; kinetic equations corresponding to various exchange mechanism hypothesis are established. It is shown that theoretical and experimental results can be compared in order to precise the mechanism and to measure the characteristic parameters of the exchange reaction [fr

  2. Synthesis and studies of modified oligonucleotides-directed triple helix formation at the purine-pyrimidine interrupted site.

    Science.gov (United States)

    Jazouli, Mohamed; Guianvarc'h, Dominique; Bougrin, Khalid; Soufiaoui, Mohamed; Vierling, Pierre; Benhida, Rachid

    2003-01-01

    Triple helix formation is still restricted to oligopurine-oligopyrimidine double stranded DNA target. Herein we focus on our progress achieved in nucleobase and oligonucleotide modifications area to address the chemical challenge to circumvent the recognition of a purine-pyrimidine base pair interruption in an oligopyrimidine-oligopurine DNA sequence.

  3. Internal conversion to the electronic ground state occurs via two distinct pathways for pyrimidine bases in aqueous solution

    OpenAIRE

    Hare, Patrick M.; Crespo-Hernández, Carlos E.; Kohler, Bern

    2006-01-01

    The femtosecond transient absorption technique was used to study the relaxation of excited electronic states created by absorption of 267-nm light in all of the naturally occurring pyrimidine DNA and RNA bases in aqueous solution. The results reveal a surprising bifurcation of the initial excited-state population in

  4. Isotopic exchange of hydrogen at C-5 in pyrimidine derivatives: tautomers with an sp3-hybridised C-5 carbon atom

    Czech Academy of Sciences Publication Activity Database

    Dračínský, Martin; Holý, Antonín; Jansa, Petr; Kovačková, Soňa; Buděšínský, Miloš

    -, č. 24 (2009), s. 4117-4122 ISSN 1434-193X R&D Projects: GA AV ČR KJB400550903 Institutional research plan: CEZ:AV0Z40550506 Keywords : isotopes * NMR spectroscopy * pyrimidines Subject RIV: CC - Organic Chemistry Impact factor: 3.096, year: 2009

  5. Modification of potentially lethal damage in irradiated Chinese hamster V79 cells after incorporation of halogenated pyrimidines

    NARCIS (Netherlands)

    Franken, N. A.; van Bree, C. V.; Kipp, J. B.; Barendsen, G. W.

    1997-01-01

    Radiosensitization of exponentially growing and plateau phase Chinese hamster V79 cells by incorporation of halogenated pyrimidines (HP) was investigated for different culture conditions that influenced repair. For this purpose cells were grown for 72 h with 0, 1, 2 and 4 microM of chloro-(CldUrd),

  6. Synthesis of 4-aryl-4,5-dihydro-1H-indeno[1,2-d]pyrimidines by ...

    Indian Academy of Sciences (India)

    Abstract. A simple and efficient method has been developed for the synthesis of series of 4-aryl-1,3,4,5- tetrahydro-2H-indeno[1,2-d]pyrimidine-2-thiones through Biginelli's one-pot multicomponent condensation reaction via microwave irradiations. Then, these thiones were converted to their S-alkylated/aralkylated deriva-.

  7. Clean Synthesis of Pyrano[2,3- D]Pyrimidines Using ZnO Nano-Powders

    Directory of Open Access Journals (Sweden)

    Maleki Nariman

    2016-07-01

    Full Text Available ZnO nano-powders were used for the one-pot synthesis of pyrano[2,3- d]pyrimidines via the solvent-free multi-component reaction of aromatic aldehydes, 1,3-dimethylbarbituric acid and malononitrile, in good to excellent yields of products.

  8. Mort Rainey's Split Personality in Secret Window

    OpenAIRE

    Sandjaya, Cynthya; Limanta, Liem Satya

    2013-01-01

    Psychological issue is the main issue discussed in David Koepp's Secret Window through its main character, Mort Rainey. Rainey's psychological struggle will be the main theme in this research. This thesis examines Rainey's split personality. Furthermore, in this study, we want to analyze the process of how Mort Rainey's personality splits into two different personalities. To meet the answer of this study, we will use the theory of Dissociative Identity Disorder with a support from Sigmund Fre...

  9. A split SUSY model from SUSY GUT

    OpenAIRE

    Wang, FeiDepartment of Physics and Engineering, Zhengzhou University, Zhengzhou, 450000, P.R. China; Wang, Wenyu(Institute of Theoretical Physics, College of Applied Science, Beijing University of Technology, Beijing, 100124, P.R. China); Yang, Jin(State Key Laboratory of Theoretical Physics, Institute of Theoretical Physics, Chinese Academy of Sciences, Beijing, 100190, P.R. China)

    2015-01-01

    We propose to split the sparticle spectrum from the hierarchy between the GUT scale and the Planck scale. A split supersymmetric model, which gives non-universal gaugino masses, is built with proper high dimensional operators in the framework of SO(10) GUT. Based on a calculation of two-loop beta functions for gauge couplings (taking into account all weak scale threshold corrections), we check the gauge coupling unification and dark matter constraints (relic density and direct detections). We...

  10. Split School of High Energy Physics 2015

    CERN Document Server

    2015-01-01

    Split School of High Energy Physics 2015 (SSHEP 2015) was held at the Faculty of Electrical Engineering, Mechanical Engineering and Naval Architecture (FESB), University of Split, from September 14 to September 18, 2015. SSHEP 2015 aimed at master and PhD students who were interested in topics pertaining to High Energy Physics. SSHEP 2015 is the sixth edition of the High Energy Physics School. Previous five editions were held at the Department of Physics, University of Sarajevo, Bosnia and Herzegovina.

  11. Are Ducted Mini-Splits Worth It?

    Energy Technology Data Exchange (ETDEWEB)

    Winkler, Jonathan M [National Renewable Energy Laboratory (NREL), Golden, CO (United States); Maguire, Jeffrey B [National Renewable Energy Laboratory (NREL), Golden, CO (United States); Metzger, Cheryn E. [Pacific Northwest National Laboratory; Zhang, Jason [Pacific Northwest National Laboratory

    2018-02-01

    Ducted mini-split heat pumps are gaining popularity in some regions of the country due to their energy-efficient specifications and their ability to be hidden from sight. Although product and install costs are typically higher than the ductless mini-split heat pumps, this technology is well worth the premium for some homeowners who do not like to see an indoor unit in their living area. Due to the interest in this technology by local utilities and homeowners, the Bonneville Power Administration (BPA) has funded the Pacific Northwest National Laboratory (PNNL) and the National Renewable Energy Laboratory (NREL) to develop capabilities within the Building Energy Optimization (BEopt) tool to model ducted mini-split heat pumps. After the fundamental capabilities were added, energy-use results could be compared to other technologies that were already in BEopt, such as zonal electric resistance heat, central air source heat pumps, and ductless mini-split heat pumps. Each of these technologies was then compared using five prototype configurations in three different BPA heating zones to determine how the ducted mini-split technology would perform under different scenarios. The result of this project was a set of EnergyPlus models representing the various prototype configurations in each climate zone. Overall, the ducted mini-split heat pumps saved about 33-60% compared to zonal electric resistance heat (with window AC systems modeled in the summer). The results also showed that the ducted mini-split systems used about 4% more energy than the ductless mini-split systems, which saved about 37-64% compared to electric zonal heat (depending on the prototype and climate).

  12. Antenna Splitting Functions for Massive Particles

    Energy Technology Data Exchange (ETDEWEB)

    Larkoski, Andrew J.; Peskin, Michael E.; /SLAC

    2011-06-22

    An antenna shower is a parton shower in which the basic move is a color-coherent 2 {yields} 3 parton splitting process. In this paper, we give compact forms for the spin-dependent antenna splitting functions involving massive partons of spin 0 and spin 1/2. We hope that this formalism we have presented will be useful in describing the QCD dynamics of the top quark and other heavy particles at LHC.

  13. Dimer-based model for heptaspanning membrane receptors.

    Science.gov (United States)

    Franco, Rafael; Casadó, Vicent; Mallol, Josefa; Ferré, Sergi; Fuxe, Kjell; Cortés, Antonio; Ciruela, Francisco; Lluis, Carmen; Canela, Enric I

    2005-07-01

    The existence of intramembrane receptor-receptor interactions for heptaspanning membrane receptors is now fully accepted, but a model considering dimers as the basic unit that binds to two ligand molecules is lacking. Here, we propose a two-state-dimer model in which the ligand-induced conformational changes from one component of the dimer are communicated to the other. Our model predicts cooperativity in binding, which is relevant because the other current models fail to address this phenomenon satisfactorily. Our two-state-dimer model also predicts the variety of responses elicited by full or partial agonists, neutral antagonists and inverse agonists. This model can aid our understanding of the operation of heptaspanning receptors and receptor channels, and, potentially, be important for improving the treatment of cardiovascular, neurological and neuropsychyatric diseases.

  14. Dimers on Surface Graphs and Spin Structures. I

    DEFF Research Database (Denmark)

    Cimasoni, David; Reshetikhin, Nicolai

    2007-01-01

    Partition functions for dimers on closed oriented surfaces are known to be alternating sums of Pfaffians of Kasteleyn matrices. In this paper, we obtain the formula for the coefficients in terms of discrete spin structures....

  15. Naturally Occurring Diterpenoid Dimers: Source, Biosynthesis, Chemistry and Bioactivities.

    Science.gov (United States)

    Lin, Li-Gen; Ung, Carolina Oi Lam; Feng, Zhe-Ling; Huang, Li; Hu, Hao

    2016-10-01

    Diterpenoid dimers are rare in nature and mainly found in higher plants including the families Acanthaceae, Annonaceae, Asteraceae, Calceolariaceae, Chrysobalanaceae, Cupressaceae, Euphorbiaceae, Fabaceae, Lamiaceae, Liliaceae, Meliaceae, Rhizophoraceae, Taxaceae, Velloziaceae, and Zingiberaceae. In addition, a few diterpenoid dimers have been also reported from fungi (Psathyrellaceae), liverworts (Scapaniaceae), and a gorgonian (Gorgoniidae). They feature a wide variety of structures due to different core skeletons, linkage patterns, substituents, and configurations. Accordingly, diterpenoid dimers exhibit a broad range of bioactivities, including cytotoxic, anti-inflammatory, antimicrobial, antimalarial, and antifouling properties, which have attracted more and more research interests in the past decades. This review with 176 metabolites from 109 references provides a comprehensive and up-to-date overview of the source, biosynthesis, structure, synthesis, and bioactivities of diterpenoid dimers. Georg Thieme Verlag KG Stuttgart · New York.

  16. Atomic model for the dimeric FOregion of mitochondrial ATP synthase.

    Science.gov (United States)

    Guo, Hui; Bueler, Stephanie A; Rubinstein, John L

    2017-11-17

    Mitochondrial adenosine triphosphate (ATP) synthase produces the majority of ATP in eukaryotic cells, and its dimerization is necessary to create the inner membrane folds, or cristae, characteristic of mitochondria. Proton translocation through the membrane-embedded F O region turns the rotor that drives ATP synthesis in the soluble F 1 region. Although crystal structures of the F 1 region have illustrated how this rotation leads to ATP synthesis, understanding how proton translocation produces the rotation has been impeded by the lack of an experimental atomic model for the F O region. Using cryo-electron microscopy, we determined the structure of the dimeric F O complex from Saccharomyces cerevisiae at a resolution of 3.6 angstroms. The structure clarifies how the protons travel through the complex, how the complex dimerizes, and how the dimers bend the membrane to produce cristae. Copyright © 2017, American Association for the Advancement of Science.

  17. Antiplasmodial dimeric chalcone derivatives from the roots of Uvaria siamensis.

    Science.gov (United States)

    Salae, Abdul-Wahab; Chairerk, Orapan; Sukkoet, Piyanut; Chairat, Therdsak; Prawat, Uma; Tuntiwachwuttikul, Pittaya; Chalermglin, Piya; Ruchirawat, Somsak

    2017-03-01

    Four dimeric chalcone derivatives, 8″,9″-dihydrowelwitschin H, uvarins A-C, a naphthalene derivative, 2-hydroxy-3-methoxy-6-(4'- hydroxyphenyl)naphthalene, and the known dimeric chalcones, dependensin and welwitschin E, flavonoids, a cyclohexane oxide derivative, an aromatic aldehyde were isolated from the roots of Uvaria siamensis (Annonaceae). The structures of the compounds were elucidated by spectroscopic analysis, as well as by comparison with literature data. The isolated compounds with a sufficient amount for biological assays were evaluated for their antimalarial, antimycobacterial, and cytotoxic activities. The dimeric chalcones 8″,9″-dihydrowelwitschin H, uvarins B and C, dependensin and welwitschin E showed strong antiplasmodial activity with IC 50 values of 3.10, 3.02, 3.09, 4.21 and 3.99 μg/mL, respectively. A possible biosynthesis pathway of the dimeric chalcones is discussed. Copyright © 2016 Elsevier Ltd. All rights reserved.

  18. Supramolecular systems based on novel mono- and dicationic pyrimidinic amphiphiles and oligonucleotides: a self-organization and complexation study.

    Science.gov (United States)

    Zakharova, Lucia; Voronin, Mikhail; Semenov, Vyacheslav; Gabdrakhmanov, Dinar; Syakaev, Victor; Gogolev, Yuri; Giniyatullin, Rashit; Lukashenko, Svetlana; Reznik, Vladimir; Latypov, Shamil; Konovalov, Alexander; Zuev, Yuri

    2012-02-01

    Novel mono- and dicationic pyrimidinic surfactants are synthesized and their aggregation behavior is studied by methods of tensiometry and nuclear magnetic resonance (NMR) self-diffusion. To estimate their potentiality as gene delivery agents, the complexation with oligonucleotides (ONus) is explored by dynamic light scattering (DLS) and zeta-potential titration methods and ethidium bromide exclusion experiments. Bola-type pyrimidinic amphiphile (BPM) demonstrates rather a weak affinity to ONus. Although it induces mixed associations with ONus, only slight charge compensation changes occur at a large excess of bola, with no recharging reached. Similarly, the ethydium bromide exclusion study reveals a slow increase in the binding capacity toward an ONu with an increment in BPM concentration. The monocationic pyrimidinic surfactant (MPM) and its gemini analogue (GPM-1) are ranked as intermediates in both their aggregative activity and complexing properties toward ONus. They both form mixed associates with ONus well below the critical micelle concentrations (cmcs) of 2 and 15 mM respectively. However, GPM-1 has a much lower isoelectric point at the molar ratio surfactant/ONu r~1 compared to r~3 for MPM. This probably indicates a larger electrostatic contribution to the ONu complexation in the case of GPM-1. The most hydrophobic pyrimidinic surfactant (GPM-2), bearing three alkyl tails, demonstrates enhanced aggregative activity and binding capacity toward ONus as compared to former pyrimidinic surfactants. Due to effective aggregative (low cmc of 0.04 mM) plus binding properties (fraction of bound ONu β=0.76 at r=2.5), GPM-2 may be ranked as a promising agent for wider biological applications. Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  19. N-1-Alkylated Pyrimidine Films as a New Potential Optical Data Storage Medium

    DEFF Research Database (Denmark)

    Lohse, Brian; Hvilsted, Søren; Berg, Rolf Henrik

    2006-01-01

    storage. Their dimerization efficiency was compared, in solution, with uracil as a reference, and as films, to investigate the correlation between solution and film. Films of good quality displaying excellent thermal and optical stability can be fabricated. A significant optical contrast between...... grating storage are also demonstrated in the films. Writing and reading of the gray scale can be performed at the same wavelength....

  20. Thymine Dimerization in DNA is an Ultrafast Photoreaction

    OpenAIRE

    Schreier, Wolfgang J.; Schrader, Tobias E.; Koller, Florian O.; Gilch, Peter; Crespo-Hernández, Carlos E.; Swaminathan, Vijay N.; Carell, Thomas; Zinth, Wolfgang; Kohler, Bern

    2007-01-01

    Femtosecond time-resolved infrared spectroscopy is used to study the formation of cyclobutane dimers in the all-thymine oligonucleotide (dT)18 by ultraviolet light at 272 nanometers. The appearance of marker bands in time-resolved spectra indicate that dimers are fully formed ∼1 picosecond after ultraviolet excitation. The ultrafast appearance of this mutagenic photolesion points to an approximately barrierless excited-state reaction for bases that are properly oriented at the instant of ligh...

  1. The influence of strain on the diffusion of Si dimers on Si(001)

    NARCIS (Netherlands)

    Zoethout, E.; Zoethout, E.; Gurlu, O.; Gürlü, O.; Zandvliet, Henricus J.W.; Poelsema, Bene

    2000-01-01

    The influence of lattice mismatch-induced tensile strain on the diffusion of Si dimers on Si(001) has been studied. The rate of surface diffusion of a Si dimer along the substrate dimer rows is relatively insensitive to tensile strain, whereas the rate of diffusion for a Si dimer across the

  2. Hydrodynamic Torques and Rotations of Superparamagnetic Bead Dimers

    Science.gov (United States)

    Pease, Christopher; Etheridge, J.; Wijesinghe, H. S.; Pierce, C. J.; Prikockis, M. V.; Sooryakumar, R.

    Chains of micro-magnetic particles are often rotated with external magnetic fields for many lab-on-a-chip technologies such as transporting beads or mixing fluids. These applications benefit from faster responses of the actuated particles. In a rotating magnetic field, the magnetization of superparamagnetic beads, created from embedded magnetic nano-particles within a polymer matrix, is largely characterized by induced dipoles mip along the direction of the field. In addition there is often a weak dipole mop that orients out-of-phase with the external rotating field. On a two-bead dimer, the simplest chain of beads, mop contributes a torque Γm in addition to the torque from mip. For dimers with beads unbound to each other, mop rotates individual beads which generate an additional hydrodynamic torque on the dimer. Whereas, mop directly torques bound dimers. Our results show that Γm significantly alters the average frequency-dependent dimer rotation rate for both bound and unbound monomers and, when mop exceeds a critical value, increases the maximum dimer rotation frequency. Models that include magnetic and hydrodynamics torques provide good agreement with the experimental findings over a range of field frequencies.

  3. Short lived maleimide triplet dimers. Kinetics and consequences

    International Nuclear Information System (INIS)

    Von Sonntag, J.

    2002-01-01

    Complete text of publication follows. The photochemistry of maleimide in non-aqueous solution is governed by the coexistence of two different triplet states, the keto triplet and a dimer triplet. This biradical is formed in the reaction of the keto triplet adding to the double bond of a ground state maleimide, in competition with electron transfer, (k 3 MI+MI = 2.6 x 10 9 dm 3 mol -1 s -1 ). Its spectrum is identical with that of the maleimide H-adduct radical (λ max = 370 ... 380 nm, broad, λ max = 255 nm, narrow, λ min = 290 nm). Its lifetime is 110 ns. While protolysis is confined to maleimide and aqueous solutions, the dimer triplet is found in acetonitrile as well. Dimer triplet formation is also observed with N-ethylmaleimide. Multi-wavelength 'global' analysis of the time profiles allowed us to separate the transient spectra and kinetics of the monomer and dimer triplet. The cyclobutane dimer yield (determined by GC) is independent of maleimide concentration. This proves that the dimer triplet does not contribute significantly to the initiation of a free-radical polymerisation. Time-dependent Hartree-Fock calculations agree with the experimental data and further confirm the proposed mechanisms

  4. Pair Interaction of Catalytical Sphere Dimers in Chemically Active Media

    Directory of Open Access Journals (Sweden)

    Jing-Min Shi

    2018-01-01

    Full Text Available We study the pair dynamics of two self-propelled sphere dimers in the chemically active medium in which a cubic autocatalytic chemical reaction takes place. Concentration gradient around the dimer, created by reactions occurring on the catalytic sphere surface and responsible for the self-propulsion, is greatly influenced by the chemical activities of the environment. Consequently, the pair dynamics of two dimers mediated by the concentration field are affected. In the particle-based mesoscopic simulation, we combine molecular dynamics (MD for potential interactions and reactive multiparticle collision dynamics (RMPC for solvent flow and bulk reactions. Our results indicate three different configurations between a pair of dimers after the collision, i.e., two possible scenarios of bound dimer pairs and one unbound dimer pair. A phase diagram is sketched as a function of the rate coefficients of the environment reactions. Since the pair interactions are the basic elements of larger scale systems, we believe the results may shed light on the understanding of the collective dynamics.

  5. VUV spectroscopy of rare gas van der Waals dimers

    International Nuclear Information System (INIS)

    Dehmer, P.M.; Pratt, S.T.

    1982-01-01

    We have undertaken a systematic study of the photoionization spectra of the homonuclear and heteronuclear rare gas dimers in order to better understand the nature of the bonding in the Rydberg states adnd ions of these molecules. We have obtained results for Ar 2 , Kr 2 , Xe 2 , NeAr, NeKr, NeXe, ArKr, ArXe, and KrXe. Of the remaining dimer species (Ne 2 and the Herare gas dimers), only Ne 2 has been studied using photoionization mass spectrometry. The results of the present series of experiments provide information both on the excited states of the neutral dimers and on the ground and excited states of the dimer ions. Using the data obtained in these measurements, we are able to compile for the first time a nearly complete list of ground state dissociation energies for the homonuclear and heteronuclear rare gas dimer ions. Somewhat less complete results are obtained for the excited states of these species. The observed trends in binding energy provide an excellent example of the systematic changes that occur as a result of changes in atomic orbital energies, polarizability, and internuclear distance, and these trends can be explained qualitatively in terms of simple molecular orbital theory

  6. Dimeric forms of cholinesterase in Sipunculus nudus.

    Science.gov (United States)

    Talesa, V; Principato, G B; Giovannini, E; Di Giovanni, M V; Rosi, G

    1993-07-15

    In developing a research on the cholinesterase (ChE) evolution in Invertebrata, this enzyme was studied in the unsegmented marine worm Sipunculus nudus. ChE activity was solubilized through three successive steps of extraction. These fractions are noted as low-salt (LSS), detergent (DS) and high-salt soluble (HSS) and represent 27%, 68% and 5% of total activity, respectively. LSS and DS ChE were purified to homogeneity by affinity chromatography on edrophonium-Sepharose gel. Purification factors of 1700 (LSS) and 1090 (DS) were obtained. The small amount of HSS ChE prevented a similar purification and an extensive characterization. Based on SDS/PAGE and density-gradient centrifugation, both LSS and DS enzymes show a M(r) value of about 130,000 and are likely G2 globular dimers of a 67,000 subunit. Moreover, LSS ChE seems to be an amphiphilic form including a hydrophobic domain, while DS ChE is probably linked to the cell membrane by a phosphatidylinositol anchor. Both LSS and DS enzymes hydrolyze at the highest rate propionylthiocholine. However, they also show a fairly high catalytic efficiency with other thiocholine esters as substrates, thus suggesting a wide and little-specialized conformation of the active site. Based on immunological cross-reactivity trials, LSS and DS ChE from S. nudus show a reduced structural affinity with a molluscan (Murex brandaris) enzyme. HSS ChE, an acetylcholinesterase, is also solubilized by heparin, like typical vertebrate HSS asymmetric enzymes. However, it lacks fast-sedimenting forms and an enzyme-anchoring collagenous structure.

  7. Syntheses and anti-microbial evaluation of new quinoline scaffold derived pyrimidine derivatives

    Directory of Open Access Journals (Sweden)

    Shikha S. Dave

    2016-09-01

    Full Text Available A series of diversely substituted chalcones derived from a quinoline scaffold, e.g. (E-3-(2-chloroquinolin-3-yl-1-(2-hydroxyphenyl prop-2-en-1-one and its pyrimidine analogues e.g. 2-[2-amino-6-(2-chloroquinolin-3-yl-5,6-dihydropyrimidin-4-yl]phenols have been prepared by condensation of 2-chloro-3-formyl quinoline with differently substituted 2-hydroxy acetophenones and further treatment with guanidine carbonate. All the newly synthesized compounds have been evaluated for their in vitro growth inhibitory activity against Escherichia coli, Pseudomonas vulgaris, Bacillus subtilis, Staphylococcus aureus, Staphylococcus typhi, Candida albicans, Aspergillus niger and Pseudomonas chrysogenum.

  8. Absolute total and partial dissociative cross sections of pyrimidine at electron and proton intermediate impact velocities

    Energy Technology Data Exchange (ETDEWEB)

    Wolff, Wania, E-mail: wania@if.ufrj.br; Luna, Hugo; Sigaud, Lucas; Montenegro, Eduardo C. [Instituto de Física, Universidade Federal do Rio de Janeiro, PO 68528, 21941-972 Rio de Janeiro, RJ (Brazil); Tavares, Andre C. [Departamento de Física, Pontificia Universidade Católica do Rio de Janeiro, PO 38071, Rua Marquês de São Vicente 225, 22453-900 Rio de Janeiro, RJ (Brazil)

    2014-02-14

    Absolute total non-dissociative and partial dissociative cross sections of pyrimidine were measured for electron impact energies ranging from 70 to 400 eV and for proton impact energies from 125 up to 2500 keV. MOs ionization induced by coulomb interaction were studied by measuring both ionization and partial dissociative cross sections through time of flight mass spectrometry and by obtaining the branching ratios for fragment formation via a model calculation based on the Born approximation. The partial yields and the absolute cross sections measured as a function of the energy combined with the model calculation proved to be a useful tool to determine the vacancy population of the valence MOs from which several sets of fragment ions are produced. It was also a key point to distinguish the dissociation regimes induced by both particles. A comparison with previous experimental results is also presented.

  9. Design, synthesis and antifungal activities of novel strobilurin derivatives containing pyrimidine moieties

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Xiang; Geo, Yongxin; Liu, Huijun; Guo, Baoyuan; Wang, Huili [Research Center for Eco-Environmental Sciences/Chinese Academy of Sciences, Beijing (China)

    2012-04-15

    Strobilurins are one of the most important classes of agricultural fungicides. To discover new strobilurin derivatives with high activity against resistant pathogens, a series of novel β-methoxy acrylate analogues were designed and synthesized by integrating substituted pyrimidine with a strobilurin pharmacophore. The compounds were confirmed and characterized by infrared, {sup 1}H nuclear magnetic resonance, elemental analysis and mass spectroscopy. The bioassays indicated that most of the compounds (1a-1h) exhibited potent antifungal activities against Colletotrichum orbicular, Botrytis cinerea Pers and Protoporphyria caps ici Leon ian at the concentration of 50 μg/mL. Exhilaratingly, compound 1d (R=3-trifluoromethylphenyl) showed better antifungal activity against all the tested fungi than the commercial stilbenetriol fungicide azoxystrobin.

  10. 4-Aminoquinoline-pyrimidine hybrids: synthesis, antimalarial activity, heme binding and docking studies.

    Science.gov (United States)

    Kumar, Deepak; Khan, Shabana I; Tekwani, Babu L; Ponnan, Prija; Rawat, Diwan S

    2015-01-07

    A series of novel 4-aminoquinoline-pyrimidine hybrids has been synthesized and evaluated for their antimalarial activity. Several compounds showed promising in vitro antimalarial activity against both CQ-sensitive and CQ-resistant strains with high selectivity index. All the compounds were found to be non-toxic to the mammalian cell lines. Selected compound 7g exhibited significant suppression of parasitemia in the in vivo assay. The heme binding studies were conducted to determine the mode of action of these hybrid molecules. These compounds form a stable 1:1 complex with hematin suggesting that heme may be one of the possible targets of these hybrids. The interaction of these conjugate hybrids was also investigated by the molecular docking studies in the binding site of PfDHFR. The pharmacokinetic property analysis of best active compounds was also studied using ADMET prediction. Copyright © 2014 Elsevier Masson SAS. All rights reserved.

  11. Design, synthesis and antifungal activities of novel strobilurin derivatives containing pyrimidine moieties

    International Nuclear Information System (INIS)

    Zhang, Xiang; Geo, Yongxin; Liu, Huijun; Guo, Baoyuan; Wang, Huili

    2012-01-01

    Strobilurins are one of the most important classes of agricultural fungicides. To discover new strobilurin derivatives with high activity against resistant pathogens, a series of novel β-methoxy acrylate analogues were designed and synthesized by integrating substituted pyrimidine with a strobilurin pharmacophore. The compounds were confirmed and characterized by infrared, 1 H nuclear magnetic resonance, elemental analysis and mass spectroscopy. The bioassays indicated that most of the compounds (1a-1h) exhibited potent antifungal activities against Colletotrichum orbicular, Botrytis cinerea Pers and Protoporphyria caps ici Leon ian at the concentration of 50 μg/mL. Exhilaratingly, compound 1d (R=3-trifluoromethylphenyl) showed better antifungal activity against all the tested fungi than the commercial stilbenetriol fungicide azoxystrobin

  12. A Comparative Study of the Corrosion Inhibitive Properties of Pyrimidine Derivatives for Mild Steel

    Directory of Open Access Journals (Sweden)

    P. Sathya

    2009-01-01

    Full Text Available The influence of pyrimidine derivatives on the corrosion inhibition of mild steel in 1 M H2SO4 was studied using weight loss and electrochemical techniques. These compounds act as good corrosion inhibitors even at low concentration and the inhibition efficiency increased with the increase in inhibition concentration. The corrosion rates have been determined at various temperatures (303-333K by weight loss measurements. The Rt values obtained from EIS method increased with increase in inhibitor concentration. The potentiostatic polarization results clearly revealed that the inhibitors behave as a mixed type but slightly anodic in nature. The adsorption process was found to obey the Langmuir adsorption isotherm. The synergistic effect of halide ion on the inhibition efficiency increase with increase concentration.

  13. Synthesis and biological evaluation of coumarin based isoxazoles, pyrimidinthiones and pyrimidin-2-ones

    Directory of Open Access Journals (Sweden)

    Divyesh Patel

    2017-05-01

    Full Text Available The titled compounds (6′a–k, (7′a–k and (8′a–k were synthesized from chalcones (5a–k having coumarin moiety. Cyclization of chalcones (5a–k with hydroxyl amine hydrochloride, thiourea and urea resulted in corresponding isoxazoles (6′a–k, pyrimidinthiones (7′a–k and pyrimidin-2-ones (8′a–k. Structures of newly synthesized compounds were established on the basis of their elemental analysis, IR, 1H NMR, 13C NMR, and mass spectral data. The synthesized analogs were evaluated for their antimycobacterial activity and antimicrobial activity against eight bacteria (Staphylococcus aureus, Bacillus cereus, Escherichia coli, Pseudomonas aeruginosa, Klebsiella pneumoniae, Salmonella typhi, Proteus vulgaris, and Shigella flexneri and four fungi (Aspergillus niger, Candida albicans, Aspergillus fumigatus, and Aspergillus clavatus.

  14. Woodfordin C, a macro-ring hydrolyzable tannin dimer with antitumor activity, and accompanying dimers from Woodfordia fruticosa flowers.

    Science.gov (United States)

    Yoshida, T; Chou, T; Nitta, A; Miyamoto, K; Koshiura, R; Okuda, T

    1990-05-01

    Three new dimeric hydrolyzable tannins, woodfordins A, B and C, along with seven known hydrolyzable tannins, including oenothein B, a dimer exhibiting marked host-mediated antitumor activity, were isolated from an Indonesian crude drug, Sidowayah [dried flowers of Woodfordia fruticosa (L.) Kurz (Lythraceae)]. The structures of the new tannins were elucidated based on chemical and spectral evidence. Woodfordin C, having a macro-ring structure, was also found to exhibit a significant antitumor activity.

  15. Molecule-binding dependent assembly of split aptamer and γ-cyclodextrin: A sensitive excimer signaling approach for aptamer biosensors

    Energy Technology Data Exchange (ETDEWEB)

    Jin, Fen [State Key Laboratory of Chemo/Biosensing and Chemometrics, College of Chemistry and Chemical Engineering, Hunan University, Changsha 410082 (China); Hubei Key Laboratory of Mine Environmental Pollution Control and Remediation, Environmental Science and Engineering College, Hubei Polytechnic University, Huangshi 435003 (China); Lian, Yan; Li, Jishan; Zheng, Jing; Hu, Yaping; Liu, Jinhua; Huang, Jin [State Key Laboratory of Chemo/Biosensing and Chemometrics, College of Chemistry and Chemical Engineering, Hunan University, Changsha 410082 (China); Yang, Ronghua, E-mail: Yangrh@pku.edu.cn [State Key Laboratory of Chemo/Biosensing and Chemometrics, College of Chemistry and Chemical Engineering, Hunan University, Changsha 410082 (China)

    2013-10-17

    Graphical abstract: Adenosine-binding aptamer was splitted into two fragments P2 and P3 which labeled pyrene molecules, mainly produce monomer signal. γ-CD cavity brings P2 and P3 in close proximity, allowing for weak excimer emission. In the presence of target, P2 and P3 are expected to bind ATP and form an aptamer/target complex, leads to large increase of the pyrene excimer fluorescence. -- Highlights: •We assembled split aptamer and γ-cyclodextrin fluorescence biosensors for ATP detection. •The biosensor increased quantum yield and emission lifetime of the excimer. •Time-resolved fluorescence is effective for ATP assay in complicated environment. -- Abstract: A highly sensitive and selective fluorescence aptamer biosensors for the determination of adenosine triphosphate (ATP) was developed. Binding of a target with splitting aptamers labeled with pyrene molecules form stable pyrene dimer in the γ-cyclodextrin (γ-CD) cavity, yielding a strong excimer emission. We have found that inclusion of pyrene dimer in γ-cyclodextrin cavity not only exhibits additive increases in quantum yield and emission lifetime of the excimer, but also facilitates target-induced fusion of the splitting aptamers to form the aptamer/target complex. As proof-of-principle, the approach was applied to fluorescence detection of adenosine triphosphate. With an anti-ATP aptamer, the approach exhibits excimer fluorescence response toward ATP with a maximum signal-to-background ratio of 32.1 and remarkably low detection limit of 80 nM ATP in buffer solution. Moreover, due to the additive fluorescence lifetime of excimer induced by γ-cyclodextrin, time-resolved measurements could be conveniently used to detect as low as 0.5 μM ATP in blood serum quantitatively.

  16. 12 CFR 7.2023 - Reverse stock splits.

    Science.gov (United States)

    2010-01-01

    ... 12 Banks and Banking 1 2010-01-01 2010-01-01 false Reverse stock splits. 7.2023 Section 7.2023... Corporate Practices § 7.2023 Reverse stock splits. (a) Authority to engage in reverse stock splits. A national bank may engage in a reverse stock split if the transaction serves a legitimate corporate purpose...

  17. Fano resonance Rabi splitting of surface plasmons.

    Science.gov (United States)

    Liu, Zhiguang; Li, Jiafang; Liu, Zhe; Li, Wuxia; Li, Junjie; Gu, Changzhi; Li, Zhi-Yuan

    2017-08-14

    Rabi splitting and Fano resonance are well-known physical phenomena in conventional quantum systems as atoms and quantum dots, arising from strong interaction between two quantum states. In recent years similar features have been observed in various nanophotonic and nanoplasmonic systems. Yet, realization of strong interaction between two or more Fano resonance states has not been accomplished either in quantum or in optical systems. Here we report the observation of Rabi splitting of two strongly coupled surface plasmon Fano resonance states in a three-dimensional plasmonic nanostructure consisting of vertical asymmetric split-ring resonators. The plasmonic system stably supports triple Fano resonance states and double Rabi splittings can occur between lower and upper pairs of the Fano resonance states. The experimental discovery agrees excellently with rigorous numerical simulations, and is well explained by an analytical three-oscillator model. The discovery of Fano resonance Rabi splitting could provide a stimulating insight to explore new fundamental physics in analogous atomic systems and could be used to significantly enhance light-matter interaction for optical sensing and detecting applications.

  18. Photochemical Water-Splitting with Organomanganese Complexes.

    Science.gov (United States)

    Kadassery, Karthika J; Dey, Suman Kr; Cannella, Anthony F; Surendhran, Roshaan; Lacy, David C

    2017-08-21

    Certain organometallic chromophores with water-derived ligands, such as the known [Mn(CO) 3 (μ 3 -OH)] 4 (1) tetramer, drew our attention as possible platforms to study water-splitting reactions. Herein, we investigate the UV irradiation of various tricarbonyl organomanganese complexes, including 1, and demonstrate that dihydrogen, CO, and hydrogen peroxide form as products in a photochemical water-splitting decomposition reaction. The organic and manganese-containing side products are also characterized. Labeling studies with 18 O-1 suggest that the source of oxygen atoms in H 2 O 2 originates from free water that interacts with 1 after photochemical dissociation of CO (1-CO) constituting the oxidative half-reaction of water splitting mediated by 1. Hydrogen production from 1 is the result of several different processes, one of which involves the protons derived from the hydroxido ligands in 1 constituting the reductive half-reaction of water splitting mediated by 1. Other processes that generate H 2 are also operative and are described. Collectively the results from the photochemical decomposition of 1 provide an opportunity to propose a mechanism, and it is discussed within the context of developing new strategies for water-splitting reactions with organomanganese complexes.

  19. Split-hand/split-foot malformation with paternal mutation in the p63 gene.

    NARCIS (Netherlands)

    Witters, I.; Bokhoven, J.H.L.M. van; Goossens, A.; Assche, F.A. van; Fryns, J.P.

    2001-01-01

    We report the prenatal diagnosis at 16 weeks' gestation of bilateral split-hand/split-foot malformation (SHSFM) with severe lobster claw deformity of hands and feet in a male fetus without associated malformations. A minor manifestation of SHSFM was present in the father with only mild bilateral

  20. Urban pattern: Layout design by hierarchical domain splitting

    KAUST Repository

    Yang, Yongliang

    2013-11-06

    We present a framework for generating street networks and parcel layouts. Our goal is the generation of high-quality layouts that can be used for urban planning and virtual environments. We propose a solution based on hierarchical domain splitting using two splitting types: streamline-based splitting, which splits a region along one or multiple streamlines of a cross field, and template-based splitting, which warps pre-designed templates to a region and uses the interior geometry of the template as the splitting lines. We combine these two splitting approaches into a hierarchical framework, providing automatic and interactive tools to explore the design space.

  1. The Jet-Cooled High-Resolution IR Spectrum of Formic Acid Cyclic Dimer

    Science.gov (United States)

    Goubet, Manuel; Bteich, Sabath; Huet, Therese R.; Pirali, Olivier; Asselin, Pierre; Soulard, Pascale; Jabri, Atef; Roy, P.; Georges, Robert

    2017-06-01

    As the simplest carboxylic acid, formic acid (FA) is an excellent model molecule to investigate the general properties of carboxylic acids. FA is also an atmospherically and astrophysically relevant molecule. It is well known that its dimeric form is predominant in the gas phase at temperatures below 423 K. The cyclic conformation of the dimer (FACD) is an elementary system to be understood for the concerted hydrogen transfer through equivalent hydrogen bonds, an essential process within biomolecules. The IR range is a crucial spectral region, particularly the far-IR, as it gives a direct access to the intermolecular vibrational modes involved in this process. Moreover, due to its centrosymmetric conformation, the FACD exhibits no pure rotation spectrum and, due to spectral line congestion and Doppler broadening, IR bands cannot be rotationally resolved at room temperature. So far, only parts of the ν_{5}-GS band (C-O stretch) have been observed under jet-cooled conditions using laser techniques. We present here six rotationally resolved IR bands of FACD recorded under jet-cooled conditions using the Jet-AILES apparatus and the QCL spectrometer at MONARIS, including the far-IR ν_{24}-GS band (intermolecular in-plane bending). Splitting due to vibration-rotation-tunneling motions are clearly observed. A full spectral analysis is in progress starting from the GS constants obtained by Goroya et al. and with the support of electronic structure calculations. T. Miyazawa and K. S. Pitzer, J. Am. Chem. Soc. 81, 74, 1959 R. Georges, M. Freytes, D. Hurtmans, I. Kleiner, J. Vander Auwera, M. Herman, Chem. Phys. 305, 187, 2004 M. Ortlieb and M. Havenith, J. Phys. Chem. A 111, 7355, 2007; K. G. Goroya, Y. Zhu, P. Sun and C. Duan, J. Chem. Phys. 140, 164311, 2014 This work is supported by the CaPPA project (Chemical and Physical Properties of the Atmosphere) ANR-11-LABX-0005-01

  2. Dimerization in Highly Concentrated Solutions of Phosphoimidazolide Activated Monomucleotides

    Science.gov (United States)

    Kanavarioti, Anastassia

    1997-08-01

    Phosphoimidazolide activated ribomononucleotides (*pN) are useful substrates for the non-enzymatic synthesis of polynucleotides. However, dilute neutral aqueous solutions of *pN typically yield small amounts of dimers and traces of polymers; most of *pN hydrolyzes to yield nucleoside 5'-monophosphate. Here we report the self-condensation of nucleoside 5'-phosphate 2-methylimidazolide (2-MeImpN with N = cytidine, uridine or guanosine) in the presence of Mg2+ in concentrated solutions, such as might have been found in an evaporating lagoon on prebiotic Earth. The product distribution indicates that oligomerization is favored at the expense of hydrolysis. At 1.0 M, 2-MeImpU and 2-MeImpC produce about 65% of oligomers including 4% of the 3',5'-linked dimer. Examination of the product distribution of the three isomeric dimers in a self-condensation allows identification of reaction pathways that lead to dimer formation. Condensations in a concentrated mixture of all three nucleotides (U,C,G mixtures) is made possible by the enhanced solubility of 2-MeImpG in such mixtures. Although percent yield of internucleotide linked dimers is enhanced as a function of initial monomer concentration, pyrophosphate dimer yields remain practically unchanged at about 20% for 2-MeImpU, 16% for 2-MeImpC and 25% of the total pyrophosphate in the U,C,G mixtures. The efficiency by which oligomers are produced in these concentrated solutions makes the evaporating lagoon scenario a potentially interesting medium for the prebiotic synthesis of dimers and short RNAs.

  3. Dimer coverings on random multiple chains of planar honeycomb lattices

    International Nuclear Information System (INIS)

    Ren, Haizhen; Zhang, Fuji; Qian, Jianguo

    2012-01-01

    We study dimer coverings on random multiple chains. A multiple chain is a planar honeycomb lattice constructed by successively fusing copies of a ‘straight’ condensed hexagonal chain at the bottom of the previous one in two possible ways. A random multiple chain is then generated by admitting the Bernoulli distribution on the two types of fusing, which describes a zeroth-order Markov process. We determine the expectation of the number of the pure dimer coverings (perfect matchings) over the ensemble of random multiple chains by the transfer matrix approach. Our result shows that, with only two exceptions, the average of the logarithm of this expectation (i.e., the annealed entropy per dimer) is asymptotically nonzero when the fusing process goes to infinity and the length of the hexagonal chain is fixed, though it is zero when the fusing process and the length of the hexagonal chain go to infinity simultaneously. Some numerical results are provided to support our conclusion, from which we can see that the asymptotic behavior fits well to the theoretical results. We also apply the transfer matrix approach to the quenched entropy and reveal that the quenched entropy of random multiple chains has a close connection with the well-known Lyapunov exponent of random matrices. Using the theory of Lyapunov exponents we show that, for some random multiple chains, the quenched entropy per dimer is strictly smaller than the annealed one when the fusing process goes to infinity. Finally, we determine the expectation of the free energy per dimer over the ensemble of the random multiple chains in which the three types of dimers in different orientations are distinguished, and specify a series of non-random multiple chains whose free energy per dimer is asymptotically equal to this expectation. (paper)

  4. Hydrogen Dimers in Giant-planet Infrared Spectra

    Science.gov (United States)

    Fletcher, Leigh N.; Gustafsson, Magnus; Orton, Glenn S.

    2018-03-01

    Despite being one of the weakest dimers in nature, low-spectral-resolution Voyager/IRIS observations revealed the presence of (H2)2 dimers on Jupiter and Saturn in the 1980s. However, the collision-induced H2–H2 opacity databases widely used in planetary science have thus far only included free-to-free transitions and have neglected the contributions of dimers. Dimer spectra have both fine-scale structure near the S(0) and S(1) quadrupole lines (354 and 587 cm‑1, respectively), and broad continuum absorption contributions up to ±50 cm‑1 from the line centers. We develop a new ab initio model for the free-to-bound, bound-to-free, and bound-to-bound transitions of the hydrogen dimer for a range of temperatures (40–400 K) and para-hydrogen fractions (0.25–1.0). The model is validated against low-temperature laboratory experiments, and used to simulate the spectra of the giant planets. The new collision-induced opacity database permits high-resolution (0.5–1.0 cm‑1) spectral modeling of dimer spectra near S(0) and S(1) in both Cassini Composite Infrared Spectrometer observations of Jupiter and Saturn, and in Spitzer Infrared Spectrometer (IRS) observations of Uranus and Neptune for the first time. Furthermore, the model reproduces the dimer signatures observed in Voyager/IRIS data near S(0) on Jupiter and Saturn, and generally lowers the amount of para-H2 (and the extent of disequilibrium) required to reproduce IRIS observations.

  5. Magnetic field effects on the soft mode in a singlet ground-state dimer system: a neutron scattering study of Cs3Cr2Br9

    DEFF Research Database (Denmark)

    Leuenberger, Bruno; Gudel, Hans U.; Feile, Rudolf

    1985-01-01

    Neutron scattering experiments in a magnetic field have been performed on the singlet ground-state dimer system Cs3Cr2Br9. At low fields the Zeeman splitting of the soft mode evolves in agreement with the isotropic random-phase approximation (RPA) model, with the notable absence of a quasielastic...... peak. At a temperature of 1.7K the expected long-range magnetic order is not found at the predicted field of 2.8 T, indicating the shortcomings of the isotropic RPA model in the critical region. Magnetic intensity on the weak nuclear Bragg peak (1¯1¯4) indicates a probable ordering with a ferromagnetic...

  6. Large Bandgap Semiconductors for Solar Water Splitting

    DEFF Research Database (Denmark)

    Malizia, Mauro

    Photoelectrochemical water splitting represents an eco-friendly technology that could enable the production of hydrogen using water as reactant and solar energy as primary energy source. The exploitation of solar energy for the production of hydrogen would help modern society to reduce the reliance...... (bismuth vanadate) was investigated in view of combining this 2.4 eV large bandgap semiconductor with a Si back-illuminated photocathode. A device obtained by mechanical stacking of BiVO4 photoanode and standard Si photocathode performs non-assisted water splitting under illumination with Solar......-to-Hydrogen efficiency lower than 0.5%. In addition, BiVO4 was synthesized on the back-side of a Si back-illuminated photocathode to produce a preliminary monolithic solar water splitting device.The Faradaic efficiency of different types of catalysts for the electrochemical production of hydrogen or oxygen was evaluated...

  7. Multiple spectral splits of supernova neutrinos.

    Science.gov (United States)

    Dasgupta, Basudeb; Dighe, Amol; Raffelt, Georg G; Smirnov, Alexei Yu

    2009-07-31

    Collective oscillations of supernova neutrinos swap the spectra f(nu(e))(E) and f(nu[over ](e))(E) with those of another flavor in certain energy intervals bounded by sharp spectral splits. This phenomenon is far more general than previously appreciated: typically one finds one or more swaps and accompanying splits in the nu and nu[over ] channels for both inverted and normal neutrino mass hierarchies. Depending on an instability condition, swaps develop around spectral crossings (energies where f(nu(e))=f(nu(x)), f(nu[over ](e))=f(nu[over ](x)) as well as E-->infinity where all fluxes vanish), and the widths of swaps are determined by the spectra and fluxes. Washout by multiangle decoherence varies across the spectrum and splits can survive as sharp spectral features.

  8. Split Notochord Syndrome: A Rare Variant

    Science.gov (United States)

    Dhawan, Vidhu; Kapoor, Kanchan; Singh, Balbir; Kochhar, Suman; Sehgal, Alka; Dada, Rima

    2017-01-01

    Split notochord syndrome represents an extremely rare and pleomorphic form of spinal dysraphism characterized by a persistent communication between the endoderm and the ectoderm, resulting in splitting or deviation of the notochord. It manifests as a cleft in the dorsal midline of the body through which intestinal loops are exteriorized and even myelomeningoceles or teratomas may occur at the site. A rare variant was diagnosed on autopsy of a 23+4-week-old fetus showing a similar dorsal enteric fistula and midline protruding intestinal loops in thoracolumbar region. The anteroposterior radiograph showed a complete midline cleft in the vertebral bodies from T11 to L5 region, and a split in the spinal cord was further confirmed by ultrasonography. Myelomeningocele was erroneously reported on antenatal ultrasound. Thus, awareness of this rare anomaly is necessary to thoroughly evaluate the cases of such spinal defects or suspected myelomeningoceles. PMID:28904581

  9. Fuzzy split and merge for shadow detection

    Directory of Open Access Journals (Sweden)

    Remya K. Sasi

    2015-03-01

    Full Text Available Presence of shadow in an image often causes problems in computer vision applications such as object recognition and image segmentation. This paper proposes a method to detect the shadow from a single image using fuzzy split and merge approach. Split and merge is a classical algorithm used in image segmentation. Predicate function in the classical approach is replaced by a Fuzzy predicate in the proposed approach. The method follows a top down approach of recursively splitting an image into homogeneous quadtree blocks, followed by a bottom up approach by merging adjacent unique regions. The method has been compared with previous approaches and found to be better in performance in terms of accuracy.

  10. PET imaging of HSV1-tk mutants with acquired specificity toward pyrimidine- and acycloguanosine-based radiotracers

    Energy Technology Data Exchange (ETDEWEB)

    Likar, Yury; Dobrenkov, Konstantin; Olszewska, Malgorzata; Shenker, Larissa; Hricak, Hedvig; Ponomarev, Vladimir [Memorial Sloan-Kettering Cancer Center, Molecular Imaging Laboratory, Department of Radiology, New York, NY (United States); Cai, Shangde [Memorial Sloan-Kettering Cancer Center, Radiochemistry/Cyclotron Core Facility, New York, NY (United States)

    2009-08-15

    The aim of this study was to create an alternative mutant of the herpes simplex virus type 1 thymidine kinase (HSV1-tk) reporter gene with reduced phosphorylation capacity for acycloguanosine derivatives, but not pyrimidine-based compounds that will allow for successful PET imaging. A new mutant of HSV1-tk reporter gene, suitable for PET imaging using pyrimidine-based radiotracers, was developed. The HSV1-tk mutant contains an arginine-to-glutamine substitution at position 176 (HSV1-R176Qtk) of the nucleoside binding region of the enzyme. The mutant-gene product showed favorable enzymatic characteristics toward pyrimidine-based nucleosides, while exhibiting reduced activity with acycloguanosine derivatives. In order to enhance HSV1-R176Qtk reporter activity with pyrimidine-based radiotracers, we introduced the R176Q substitution into the more active HSV1-sr39tk mutant. U87 human glioma cells transduced with the HSV1-R176Qsr39tk double mutant reporter gene showed high {sup 3}H-FEAU pyrimidine nucleoside and low {sup 3}H-penciclovir acycloguanosine analog uptake in vitro. PET imaging also demonstrated high {sup 18}F-FEAU and low {sup 18}F-FHBG accumulation in HSV1-R176Qsr39tk+ xenografts. The feasibility of imaging two independent nucleoside-specific HSV1-tk mutants in the same animal with PET was demonstrated. Two opposite xenografts expressing the HSV1-R176Qsr39tk reporter gene and the previously described acycloguanosine-specific mutant of HSV1-tk, HSV1-A167Ysr39tk reporter gene, were imaged using a short-lived pyrimidine-based {sup 18}F-FEAU and an acycloguanosine-based {sup 18}F-FHBG radiotracer, respectively, administered on 2 consecutive days. We conclude that in combination with acycloguanosine-specific HSV1-A167Ysr39tk reporter gene, a HSV1-tk mutant containing the R176Q substitution could be used for PET imaging of two different cell populations or concurrent molecular biological processes in the same living subject. (orig.)

  11. Faster multiple emulsification with drop splitting.

    Science.gov (United States)

    Abate, Adam R; Weitz, David A

    2011-06-07

    Microfluidic devices can form emulsions in which the drops have an intricate, controlled structure; however, a challenge is that the droplets are produced slowly, typically only a few millilitres per hour. Here, we present a simple technique to increase the production rate. Using a large drop maker, we produce large drops at a fast volumetric rate; by splitting these drops several times in a splitting array, we create drops of the desired small size. The advantage of this over forming the small drops directly using a small drop maker is that the drops can be formed at much faster rates. This can be applied to the production of single and multiple emulsions.

  12. Splitting Strategy for Simulating Genetic Regulatory Networks

    Directory of Open Access Journals (Sweden)

    Xiong You

    2014-01-01

    Full Text Available The splitting approach is developed for the numerical simulation of genetic regulatory networks with a stable steady-state structure. The numerical results of the simulation of a one-gene network, a two-gene network, and a p53-mdm2 network show that the new splitting methods constructed in this paper are remarkably more effective and more suitable for long-term computation with large steps than the traditional general-purpose Runge-Kutta methods. The new methods have no restriction on the choice of stepsize due to their infinitely large stability regions.

  13. Hyperfine splitting in lithium-like bismuth

    Energy Technology Data Exchange (ETDEWEB)

    Lochmann, Matthias; Froemmgen, Nadja; Hammen, Michael; Will, Elisa [Universitaet Mainz (Germany); Andelkovic, Zoran; Kuehl, Thomas; Litvinov, Yuri; Winters, Danyal; Sanchez, Rodolfo [GSI Helmholtzzentrum, Darmstadt (Germany); Botermann, Benjamin; Noertershaeuser, Wilfried [Technische Universitaet Darmstadt (Germany); Bussmann, Michael [Helmholtzzentrum Dresden-Rossendorf (Germany); Dax, Andreas [CERN, Genf (Switzerland); Hannen, Volker; Joehren, Raphael; Vollbrecht, Jonas; Weinheimer, Christian [Universitaet Muenster (Germany); Geppert, Christopher [Universitaet Mainz (Germany); GSI Helmholtzzentrum, Darmstadt (Germany); Stoehlker, Thomas [GSI Helmholtzzentrum, Darmstadt (Germany); Universitaet Heidelberg (Germany); Thompson, Richard [Imperial College, London (United Kingdom); Volotka, Andrey [Technische Universitaet Dresden (Germany); Wen, Weiqiang [IMP Lanzhou (China)

    2013-07-01

    High-precision measurements of the hyperfine splitting values on Li- and H-like bismuth ions, combined with precise atomic structure calculations allow us to test QED-effects in the regime of the strongest magnetic fields that are available in the laboratory. Performing laser spectroscopy at the experimental storage ring (ESR) at GSI Darmstadt, we have now succeeded in measuring the hyperfine splitting in Li-like bismuth. Probing this transition has not been easy because of its extremely low fluorescence rate. Details about this challenging experiment will be given and the achieved experimental accuracy are presented.

  14. Glycine transporter dimers: evidence for occurrence in the plasma membrane.

    Science.gov (United States)

    Bartholomäus, Ingo; Milan-Lobo, Laura; Nicke, Annette; Dutertre, Sébastien; Hastrup, Hanne; Jha, Alok; Gether, Ulrik; Sitte, Harald H; Betz, Heinrich; Eulenburg, Volker

    2008-04-18

    Different Na(+)/Cl(-)-dependent neurotransmitter transporters of the SLC6a family have been shown to form dimers or oligomers in both intracellular compartments and at the cell surface. In contrast, the glycine transporters (GlyTs) GlyT1 and -2 have been reported to exist as monomers in the plasma membrane based on hydrodynamic and native gel electrophoretic studies. Here, we used cysteine substitution and oxidative cross-linking to show that of GlyT1 and GlyT2 also form dimeric complexes within the plasma membrane. GlyT oligomerization at the cell surface was confirmed for both GlyT1 and GlyT2 by fluorescence resonance energy transfer microscopy. Endoglycosidase treatment and surface biotinylation further revealed that complex-glycosylated GlyTs form dimers located at the cell surface. Furthermore, substitution of tryptophan 469 of GlyT2 by an arginine generated a transporter deficient in dimerization that was retained intracellulary. Based on these results and GlyT structures modeled by using the crystal structure of the bacterial homolog LeuT(Aa), as a template, residues located within the extracellular loop 3 and at the beginning of transmembrane domain 6 are proposed to contribute to the dimerization interface of GlyTs.

  15. Effects of Dimerization of Serratia marcescens Endonuclease on Water Dynamics.

    Energy Technology Data Exchange (ETDEWEB)

    Chen, Chuanying; Beck, Brian W.; Krause, Kurt; Weksberg, Tiffany E.; Pettitt, Bernard M.

    2007-02-15

    The research described in this product was performed in part in the Environmental Molecular Sciences Laboratory, a national scientific user facility sponsored by the Department of Energy's Office of Biological and Environmental Research and located at Pacific Northwest National Laboratory. The dynamics and structure of Serratia marcescens endonuclease and its neighboring solvent are investigated by molecular dynamics (MD). Comparisons are made with structural and biochemical experiments. The dimer form is physiologic and functions more processively than the monomer. We previously found a channel formed by connected clusters of waters from the active site to the dimer interface. Here, we show that dimerization clearly changes correlations in the water structure and dynamics in the active site not seen in the monomer. Our results indicate that water at the active sites of the dimer is less affected compared with bulk solvent than in the monomer where it has much slower characteristic relaxation times. Given that water is a required participant in the reaction, this gives a clear advantage to dimerization in the absence of an apparent ability to use both active sites simultaneously.

  16. Phenylamino-pyrimidine (PAP) derivatives: a new class of potent and selective inhibitors of protein kinase C (PKC).

    Science.gov (United States)

    Zimmermann, J; Caravatti, G; Mett, H; Meyer, T; Müller, M; Lydon, N B; Fabbro, D

    1996-07-01

    Phenylamino-pyrimidines represent a novel class of inhibitors of the protein kinase C with a high degree of selectivity versus other serine/threonine and tyrosine kinases. Steady state kinetic analysis of N-(3-[1-imidazolyl]-phenyl-4-(3-pyridyl)-2-pyrimidinamine (5), which showed potent inhibitory activity, revealed competitive kinetics relative to ATP. The adjacent H-bond acceptor of the pyrimidine moiety next to an H-bond donor of the phenylamine was found to be crucial for inhibitory activity. N-(3-Nitro-phenyl)-4-(3-pyridyl)-2-pyrimidinamine (7) preferentially inhibited PKC-alpha (IC50 = 0.79 microM) and not the other subtypes tested. The inhibition constants of PKC-alpha and the antiproliferative effect on T24 human bladder carcinoma cells showed a qualitative correlation, although with some exceptions.

  17. QSAR study of some pyrazolo[3,4-d]pyrimidine derivatives as the c-Src inhibitors

    Science.gov (United States)

    Shukla, Bindesh Kumar; Yadava, Umesh

    2016-05-01

    Two dimensional quantitative structure activity relationship (QSAR) studies have been carried out on a series of 42 pyrazolo[3,4-d]pyrimidine derivatives to find out the structural requirements for the inhibition of c-SRC phosphorilation. The best predictions were obtained using Heuristic and Best MLR methods from the model where 33 compounds were considered in the training set and the remaining 9 in the test set. Both Best MLR and Heuristic methods indicate that squared correlation coefficient for training and test sets are very close to observed biological activities which designate the good correlation between the experimental and predicted activity. The results that are obtained from 2D-QSAR studies may provide useful insights into the roles of various substitution patterns on the pyrazolo[3,4-d]pyrimidine core and may also help to design more potent compounds.

  18. Synthesis of Some Novel Pyrazolo[1,5-a]pyrimidine Derivatives and Their Application as Disperse Dyes

    Directory of Open Access Journals (Sweden)

    Alya M. Al-Etaibi

    2011-06-01

    Full Text Available A series of novel monoazo-disperse dyes containing pyrazolo[1,5-a]pyrimidine structures were synthesized starting with the coupling reaction between ethyl cyanoacetate and 4-hydroxybenzenediazonium chloride, followed by treatment of the resulting hydrazone product with hydrazine hydrate. The pyrazolohydrazone 6 is then treated with either 2,4-pentandione and enaminonitrile or aryl-substituted enaminoketones to give the target pyrazolo[1,5-a]pyrimidine dyes 7 and 15a-d. Structural assignments to the dyes were made using NMR spectroscopic methods. A new high temperature method, using microwave heating, was employed to apply these dyes to polyester fibers. Most of the dyed fabrics tested displayed moderate light fastness and excellent washing fastness properties.

  19. Systematic structure modifications of imidazo[1,2-a]pyrimidine to reduce metabolism mediated by aldehyde oxidase (AO).

    Science.gov (United States)

    Linton, Angelica; Kang, Ping; Ornelas, Martha; Kephart, Susan; Hu, Qiyue; Pairish, Mason; Jiang, Ying; Guo, Chuangxing

    2011-11-10

    N-{trans-3-[(5-Cyano-6-methylpyridin-2-yl)oxy]-2,2,4,4-tetramethylcyclobutyl}imidazo[1,2-a]pyrimidine-3-carboxamide (1) was recently identified as a full antagonist of the androgen receptor, demonstrating excellent in vivo tumor growth inhibition in castration-resistant prostate cancer (CRPC). However, the imidazo[1,2-a]pyrimidine moiety is rapidly metabolized by aldehyde oxidase (AO). The present paper describes a number of medicinal chemistry strategies taken to avoid the AO-mediated oxidation of this particular system. Guided by an AO protein structure-based model, our investigation revealed the most probable site of AO oxidation and the observation that altering the heterocycle or blocking the reactive site are two of the more effective strategies for reducing AO metabolism. These strategies may be useful for other drug discovery programs.

  20. Discrete objects, splitting closure and connectedness | Castellini ...

    African Journals Online (AJOL)

    Notions of discrete and indiscrete classes with respect to a closure operator are introduced and studied. These notions are strongly related to splitting and cosplitting closure operators. By linking the above concepts, two Galois connections arise whose composition provides a third Galois connection that can be used as a ...

  1. Miniaturized Planar Split-Ring Resonator Antenna

    DEFF Research Database (Denmark)

    Kim, Oleksiy S.; Breinbjerg, Olav

    2009-01-01

    A miniaturized planar antenna based on a broadside-coupled split ring resonator excited by an arc-shaped dipole is presented. The excitation dipole acts as a small tuning capacitor in series with a parallel RLC circuit represented by the SRR. The antenna resonance frequency and dimensions...

  2. Split Coil Forms for Rotary Transformers

    Science.gov (United States)

    Mclyman, C. W. T.

    1982-01-01

    Split cores for rotor and stator windings of rotary transformer mounted around their respective coils (which are in bobbins) and cemented together. This arrangement simplifies winding of stator coil to go in a slot in inner diameter of stator coil. One practical application of rotary transformers fabricated according to this technique is for centrifuges, in which conventional sliprings are of uncertain reliability.

  3. Split Beta-Lactamase Complementation Assay

    Indian Academy of Sciences (India)

    IAS Admin

    Concept of split beta. -lactamase protein fragment complementation assay. (A) and (B) are vector systems involved in the assay. As an example, a vector system for bacterial host is described here. (C) Co-transformation of complementation vectors in appropriate bacterial host. (D) and (E) are types of inter- actions expected ...

  4. Molecular catalytic system for efficient water splitting

    NARCIS (Netherlands)

    Joya, Khurram Saleem

    2011-01-01

    The aim of this dissertation is to construct and explore artificial oxygen evolving complexes that are synthetically accessible, stable, functionally robust and efficient. To achieve this, a class of mono metal water splitting catalysts is introduced in this manuscript and exploitation of these

  5. Splitting up Beta’s change

    OpenAIRE

    Suarez, Ronny

    2014-01-01

    In this paper we estimated IBM beta from 2000 to 2013, then using differential equation mathematical formula we split up the annual beta’s change attributed to the volatility market effect, the stock volatility effect, the correlation effect and the jointly effect of these variables.

  6. Shear-wave splitting and moonquakes

    Science.gov (United States)

    Dimech, J. L.; Weber, R. C.; Savage, M. K.

    2017-12-01

    Shear-wave splitting is a powerful tool for measuring anisotropy in the Earth's crust and mantle, and is sensitive to geological features such as fluid filled cracks, thin alternating layers of rock with different elastic properties, and preferred mineral orientations caused by strain. Since a shear wave splitting measurement requires only a single 3-component seismic station, it has potential applications for future single-station planetary seismic missions, such as the InSight geophysical mission to Mars, as well as possible future missions to Europa and the Moon. Here we present a preliminary shear-wave splitting analysis of moonquakes detected by the Apollo Passive Seismic Experiment. Lunar seismic data suffers from several drawbacks compared to modern terrestrial data, including severe seismic scattering, low intrinsic attenuation, 10-bit data resolution, thermal spikes, and timing errors. Despite these drawbacks, we show that it is in principle possible to make a shear wave splitting measurement using the S-phase arrival of a relatively high-quality moonquake, as determined by several agreeing measurement criteria. Encouraged by this finding, we further extend our analysis to clusters of "deep moonquake" events by stacking multiple events from the same cluster together to further enhance the quality of the S-phase arrivals that the measurement is based on.

  7. Split brain: divided perception but undivided consciousness.

    Science.gov (United States)

    Pinto, Yair; Neville, David A; Otten, Marte; Corballis, Paul M; Lamme, Victor A F; de Haan, Edward H F; Foschi, Nicoletta; Fabri, Mara

    2017-05-01

    In extensive studies with two split-brain patients we replicate the standard finding that stimuli cannot be compared across visual half-fields, indicating that each hemisphere processes information independently of the other. Yet, crucially, we show that the canonical textbook findings that a split-brain patient can only respond to stimuli in the left visual half-field with the left hand, and to stimuli in the right visual half-field with the right hand and verbally, are not universally true. Across a wide variety of tasks, split-brain patients with a complete and radiologically confirmed transection of the corpus callosum showed full awareness of presence, and well above chance-level recognition of location, orientation and identity of stimuli throughout the entire visual field, irrespective of response type (left hand, right hand, or verbally). Crucially, we used confidence ratings to assess conscious awareness. This revealed that also on high confidence trials, indicative of conscious perception, response type did not affect performance. These findings suggest that severing the cortical connections between hemispheres splits visual perception, but does not create two independent conscious perceivers within one brain. © The Author (2017). Published by Oxford University Press on behalf of the Guarantors of Brain. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

  8. Helioseismic Solar Cycle Changes and Splitting Coefficients

    Indian Academy of Sciences (India)

    tribpo

    Abstract. Using the GONG data for a period over four years, we have studied the variation of frequencies and splitting coefficients with solar cycle. Frequencies and even-order coefficients are found to change signi- ficantly with rising phase of the solar cycle. We also find temporal varia- tions in the rotation rate near the solar ...

  9. Czech, Slovak science ten years after split

    CERN Multimedia

    2003-01-01

    Ten years after the split of Czechoslovakia Czech and Slovak science are facing the same difficulties: shortage of money for research, poor salaries, obsolete equipment and brain drain, especially of the young, according to a feature in the Daily Lidove Noviny (1 page).

  10. Comparing Electrochemical and Biological Water Splitting

    DEFF Research Database (Denmark)

    Rossmeisl, Jan; Dimitrievski, Kristian; Siegbahn, P.

    2007-01-01

    On the basis of density functional theory calculations, we compare the free energies of key intermediates in the water splitting reaction over transition metal oxide surfaces to those of the Mn cluster in photo system II. In spite of the very different environments in the enzyme system...

  11. Optofluidic taming of a colloidal dimer with a silicon nanocavity

    Energy Technology Data Exchange (ETDEWEB)

    Pin, C.; Renaut, C. [Groupe d' Optique de Champ Proche - LRC CEA n°DSM-08-36, Laboratoire Interdisciplinaire Carnot de Bourgogne, UMR CNRS n°6303- Université de Bourgogne, Dijon (France); University Grenoble Alpes, INAC-SP2M-SINAPS, F-38000 Grenoble, France and CEA, INAC-SP2M-SINAPS, F-38000 Grenoble (France); University Grenoble Alpes, CNRS, CEA-Leti Minatec, LTM, F-38054 Grenoble Cedex (France); Cluzel, B., E-mail: benoit.cluzel@u-bourgogne.fr; Fornel, F. de [Groupe d' Optique de Champ Proche - LRC CEA n°DSM-08-36, Laboratoire Interdisciplinaire Carnot de Bourgogne, UMR CNRS n°6303- Université de Bourgogne, Dijon (France); Peyrade, D. [University Grenoble Alpes, CNRS, CEA-Leti Minatec, LTM, F-38054 Grenoble Cedex (France); Picard, E.; Hadji, E. [University Grenoble Alpes, INAC-SP2M-SINAPS, F-38000 Grenoble, France and CEA, INAC-SP2M-SINAPS, F-38000 Grenoble (France)

    2014-10-27

    We report here the optical trapping of a heterogeneous colloidal dimer above a photonic crystal nanocavity used as an on-chip optical tweezer. The trapped dimer consists of a cluster of two dielectric microbeads of different sizes linked by van der Waals forces. The smallest bead, 1 μm in diameter, is observed to be preferentially trapped by the nanotweezer, leaving the second bead untrapped. The rotational nature of the trapped dimer Brownian motion is first evidenced. Then, in the presence of a fluid flow, control of its orientation and rotation is achieved. The whole system is found to show high rotational degrees of freedom, thereby acting as an effective flow-sensitive microscopic optical ball joint.

  12. Comparative study of purine and pyrimidine nucleoside analogues acting on the thymidylate kinases of Mycobacterium tuberculosis and of humans.

    OpenAIRE

    Pochet , Sylvie; Dugué , Laurence; Labesse , Gilles; Delepierre , Muriel; Munier-Lehmann , Hélène

    2003-01-01

    Thymidine monophosphate kinase (TMPK) from Mycobacterium tuberculosis (TMPKmt) is an attractive target for the design of specific inhibitors. This fact is the result of its key role in the thymidine pathway and of unique structural features in the active site observed by X-ray crystallography, especially in comparison to its human counterpart (TMPKh). Different 5-modified thymidine derivatives, as well as purine and pyrimidine analogues or C-nucleosides were tested on TMPKmt and TMPKh, and th...

  13. Novel N-(pyrimidin-4-ylthiazol-2-amine derivatives as dual-action hypoglycemic agents that activate GK and PPARγ

    Directory of Open Access Journals (Sweden)

    Hui-peng Song

    2011-10-01

    Full Text Available A series of novel N-(pyrimidin-4-ylthiazol-2-amine derivatives have been synthesized and evaluated as glucokinase (GK activators. Ethyl 2-(6-(4-(2-hydroxyethylpiperazin-1-yl-2-methylpyrimidin-4-yl-aminothiazole-5-carboxylate was found to be a potent dual-acting hypoglycemic agent activating both GK and PPARγ. When given orally to normal mice, the compound demonstrated significant efficacy in decreasing the glucose level after oral glucose loading.

  14. Acyclic nucleoside bisphosphonates: Synthesis and properties of chiral 2-amino-4,6-bis[(phosphonomethoxy)alkoxy]pyrimidines

    Czech Academy of Sciences Publication Activity Database

    Doláková, Petra; Dračínský, Martin; Masojídková, Milena; Šolínová, Veronika; Kašička, Václav; Holý, Antonín

    2009-01-01

    Roč. 44, č. 6 (2009), s. 2408-2424 ISSN 0223-5234 R&D Projects: GA MŠk 1M0508 Grant - others:NIH(US) 1UC1AIO62540-01 Institutional research plan: CEZ:AV0Z40550506 Keywords : acyclic nucleoside phosphonates * pyrimidine * bisphosphonates Subject RIV: CC - Organic Chemistry Impact factor: 3.269, year: 2009

  15. 5,6,7-trisubstituted 4-aminopyrido[2,3-d]pyrimidines as novel inhibitors of adenosine kinase.

    Science.gov (United States)

    Perner, Richard J; Gu, Yu-Gui; Lee, Chih-Hung; Bayburt, Erol K; McKie, Jeffery; Alexander, Karen M; Kohlhaas, Kathy L; Wismer, Carol T; Mikusa, Joe; Jarvis, Michael F; Kowaluk, Elizabeth A; Bhagwat, Shripad S

    2003-11-20

    The synthesis and structure-activity relationship of a series of 5,6,7-trisubstituted 4-aminopyrido[2,3-d]pyrimidines as novel nonnucleoside adenosine kinase inhibitors is described. A variety of alkyl, aryl, and heteroaryl substituents were found to be tolerated at the C5, C6, and C7 positions of the pyridopyrimidine core. These studies have led to the identification of analogues that are potent inhibitors of adenosine kinase with in vivo analgesic activity.

  16. Crystal structure of 1-methyl-4-methylsulfanyl-1H-pyrazolo[3,4-d]pyrimidine

    Directory of Open Access Journals (Sweden)

    Mohammed El Fal

    2014-12-01

    Full Text Available In the title compound, C7H8N4S, the non-H atoms of the pyrazolo[3,4-d]pyrimidine ring system and the methylsulfanyl group lie on a crystallographic mirror plane. In the crystal, molecules are linked via a number of π–π interactions [centroid–centroid distances vary from 3.452 (7 to 3.6062 (8 Å], forming a three-dimensional structure.

  17. Syntheses of pyrimidine acyclic nucleoside phosphonates as potent inhibitors of thymidine phosphorylase (PD-ECGF) from SD-lymphoma

    Czech Academy of Sciences Publication Activity Database

    Pomeisl, Karel; Votruba, Ivan; Holý, Antonín; Pohl, Radek

    2007-01-01

    Roč. 26, 8/9 (2007), s. 1025-1028 ISSN 1525-7770. [International Roundtable /17./. Bern, 03.09.2006-07.09.2006] R&D Projects: GA MŠk 1M0508 Grant - others:Descartes Prize(XE) HPAW-CT-2002-9001 Institutional research plan: CEZ:AV0Z40550506 Keywords : acyclic nucleoside phosphonates * thymidine phosphorylase * pyrimidines * FPMP derivatives * fluor ination Subject RIV: CC - Organic Chemistry Impact factor: 0.723, year: 2007

  18. Glutaminase and poly(ADP-ribose) polymerase inhibitors suppress pyrimidine synthesis and VHL-deficient renal cancers

    Science.gov (United States)

    Okazaki, Arimichi; Gameiro, Paulo A.; Christodoulou, Danos; Laviollette, Laura; Schneider, Meike; Chaves, Frances; Stemmer-Rachamimov, Anat; Yazinski, Stephanie A.; Lee, Richard; Stephanopoulos, Gregory; Zou, Lee

    2017-01-01

    Many cancer-associated mutations that deregulate cellular metabolic responses to hypoxia also reprogram carbon metabolism to promote utilization of glutamine. In renal cell carcinoma (RCC), cells deficient in the von Hippel–Lindau (VHL) tumor suppressor gene use glutamine to generate citrate and lipids through reductive carboxylation (RC) of α-ketoglutarate (αKG). Glutamine can also generate aspartate, the carbon source for pyrimidine biosynthesis, and glutathione for redox balance. Here we have shown that VHL–/– RCC cells rely on RC-derived aspartate to maintain de novo pyrimidine biosynthesis. Glutaminase 1 (GLS1) inhibitors depleted pyrimidines and increased ROS in VHL–/– cells but not in VHL+/+ cells, which utilized glucose oxidation for glutamate and aspartate production. GLS1 inhibitor–induced nucleoside depletion and ROS enhancement led to DNA replication stress and activation of an intra–S phase checkpoint, and suppressed the growth of VHL–/– RCC cells. These effects were rescued by administration of glutamate, αKG, or nucleobases with N-acetylcysteine. Further, we observed that the poly(ADP-ribose) polymerase (PARP) inhibitor olaparib synergizes with GLS1 inhibitors to suppress the growth of VHL–/– cells in vitro and in vivo. This work describes a mechanism that explains the sensitivity of RCC tumor growth to GLS1 inhibitors and supports the development of therapeutic strategies for targeting VHL-deficient RCC. PMID:28346230

  19. Analgesic Activity of Some 1,2,4-Triazole Heterocycles Clubbed with Pyrazole, Tetrazole, Isoxazole and Pyrimidine

    Directory of Open Access Journals (Sweden)

    Ramdas Bhanudas Pandhare

    2013-02-01

    Full Text Available Purpose: In the present study in vivo analgesic activity of some previously synthesized 1,2,4-triazole derivatives containing pyrazole, tetrazole, isoxazole and pyrimidine ring have been evaluated. Methods: Acetic acid induced writhing method and Hot plate method has been described to study analgesic activity of some 1,2,4-triazole derivatives containing pyrazole, tetrazole, isoxazole and pyrimidine as a pharmacological active lead. Results: Thirty six different derivatives containing 1,2,4-triazole ring were subjected to study their in vivo analgesic activity. Chloro, nitro and methoxy, hydroxy and bromo substituted derivatives showed excellent analgesic activity and dimethylamino, furan and phenyl substituted derivatives showed moderate analgesic activity in both of the methods. Compounds IIIa, IIId, IIIf, IIIi, IIIj, IVa, IVb, IVd, IVf, IVh, IVj IV3a and IIj were found to be superior analgesic agents after screening by Acetic acid induced writhing method. Compounds IIIb, IIId, IIIf, IIIh, IIIj, IVa, IVb, IVd, IVf, IVh, IVi, IV3c, IV3e and IIj were showed analgesic potential after screening of Hot plate method. Conclusion: All tested compounds containing 1,2,4-triazole were found to be promising analgesic agents, for this activity pyrazole, tetrazole, isoxazole and pyrimidine leads might be supported.

  20. Formation of uracil from the ultraviolet photo-irradiation of pyrimidine in pure H2O ices.

    Science.gov (United States)

    Nuevo, Michel; Milam, Stefanie N; Sandford, Scott A; Elsila, Jamie E; Dworkin, Jason P

    2009-09-01

    The detection of nucleobases in carbonaceous chondrites such as Murchison supports the scenario in which extraterrestrial organic molecules could have contributed to the origin of life on Earth. However, such large molecules have not been observed to date in astrophysical environments, in particular, comets and the interstellar medium (ISM). The physico-chemical conditions under which nucleobases and, more generally, N-heterocycles were formed are unknown, as are their mechanisms of formation. In this work, H2O:pyrimidine ice mixtures were irradiated with UV photons under interstellar/cometary-relevant conditions to study the formation of pyrimidine derivatives, including the nucleobase uracil. Liquid and gas chromatography analyses of the samples produced in our experiments revealed the presence of numerous photoproducts among which 4(3H)-pyrimidone and uracil could be conclusively identified. The photostability of pyrimidine against UV photons was also studied, and we showed that it would survive from the ISM to the solar nebula if formed and preserved in ice mantles on the surface of cold grains. We propose pathways for the formation of 4(3H)-pyrimidone and uracil under astrophysically relevant conditions and discuss the possibility for such molecules to survive from the ISM to their delivery to Earth and other Solar System bodies.

  1. Dimerization effect of sucrose octasulfate on rat FGF1

    DEFF Research Database (Denmark)

    Kulahin, Nikolaj; Kiselyov, Vladislav; Kochoyan, Artur

    2008-01-01

    signalling pathways. The structure of rat FGF1 crystallized in the presence of SOS has been determined at 2.2 A resolution. SOS-mediated dimerization of FGF1 was observed, which was further supported by gel-filtration experiments. The major contributors to the sulfate-binding sites in rat FGF1 are Lys113......, Lys118, Arg122 and Lys128. An arginine at position 116 is a consensus residue in mammalian FGF molecules; however, it is a serine in rat FGF1. This difference may be important for SOS-mediated FGF1 dimerization in rat....

  2. Construction of covalently coupled, concatameric dimers of 7TM receptors

    DEFF Research Database (Denmark)

    Terpager, Marie; Scholl, D Jason; Kubale, Valentina

    2009-01-01

    -Ala repeats flanked by flexible spacers and positively charged residues to ensure correct inside-out orientation plus an extracellular HA-tag to construct covalently coupled dimers of 7TM receptors. Such 15 TM concatameric homo- and heterodimers of the beta(2)-adrenergic and the NK(1) receptors, which...... for either of the protomers, which was not observed upon simple coexpression of the two receptors. It is concluded that covalently joined 7TM receptor dimers with surprisingly normal receptor properties can be constructed with use of an artificial transmembrane connector, which perhaps can be used to fuse...

  3. Dimer-flipping-assisted diffusion on a Si(001) surface

    International Nuclear Information System (INIS)

    Zi, J.; Min, B. J.; Lu, Y.; Wang, C. Z.; Ho, K. M.

    2000-01-01

    The binding sites and diffusion pathways of Si adatoms on a c(4x2) reconstructed Si(001) surface are investigated by a tight-binding method with an environment-dependent silicon potential in conjunction with ab initio calculations using the Car--Parrinello method. A new diffusion pathway along the trough edge driven by dimer flipping is found with a barrier of 0.74 eV, comparable to that of 0.68 eV along the top of the dimer rows

  4. Measurement of oxidative damage at pyrimidine bases in gamma-irradiated DNA.

    Science.gov (United States)

    Douki, T; Delatour, T; Paganon, F; Cadet, J

    1996-01-01

    Oxidized nucleobases represent one of the main classes of damage induced in DNA by ionizing radiation. Emphasis was placed in this work on the measurement of four oxidized pyrimidine bases, including 5-(hydroxymethyl)uracil (5-HMUra), 5-formyluracil (5-ForUra), 5-hydroxycytosine (5-OHCyt), and 5-hydroxyuracil (5-OHUra), in isolated DNA upon exposure to gamma radiation in aerated aqueous solution. For this purpose, both high performance liquid chromatography associated with electrochemical detection (HPLC-EC) and gas chromatography coupled to mass spectrometry (GC-MS) were used. Conditions of hydrolysis of the N-glycosidic bond were carefully checked in order to achieve a quantitative release of the lesions. We showed that 60% formic acid treatment leads to the decomposition of the four lesions studied. On the other hand, hydrolysis based on the use of either 88% formic acid or 70% hydrogen fluoride in pyridine (HF/Pyr) allowed the quantitative release of the modified bases, with the exception of 5-HMUra when the latter reagent was utilized. A dose course study of the radiation-induced formation of 5-HMUra and 5-ForUra in DNA by using the GC-MS assay showed that the latter lesion was produced in a 2.1-fold higher yield than the former one. HF/Pyr and 88% formic acid hydrolysis provided similar results for 5-ForUra, indicating the reliability of both techniques for the measurement of this lesion. For 5-OHUra and 5-OHCyt, the level of modification determined by GC-MS analysis was higher after 88% formic acid treatment than upon HF/Pyr hydrolysis. When DNA was enzymatically digested and analyzed by HPLC-EC for 5-OHdCyd and 5-OHdUrd, the results were very close to those obtained by GC-MS following HF/Pyr treatment. It was concluded that additional amounts of both 5-OHUra and 5-OHCyt are produced during the 88% formic acid treatment from radiation-induced 5,6-saturated pyrimidine precursors. It is likely that cytosine and uracil diols are involved in this reaction. The

  5. Biophysical characterization of the dimer and tetramer interface interactions of the human cytosolic malic enzyme.

    Science.gov (United States)

    Murugan, Sujithkumar; Hung, Hui-Chih

    2012-01-01

    The cytosolic NADP(+)-dependent malic enzyme (c-NADP-ME) has a dimer-dimer quaternary structure in which the dimer interface associates more tightly than the tetramer interface. In this study, the urea-induced unfolding process of the c-NADP-ME interface mutants was monitored using fluorescence and circular dichroism spectroscopy, analytical ultracentrifugation and enzyme activities. Here, we demonstrate the differential protein stability between dimer and tetramer interface interactions of human c-NADP-ME. Our data clearly demonstrate that the protein stability of c-NADP-ME is affected predominantly by disruptions at the dimer interface rather than at the tetramer interface. First, during thermal stability experiments, the melting temperatures of the wild-type and tetramer interface mutants are 8-10°C higher than those of the dimer interface mutants. Second, during urea denaturation experiments, the thermodynamic parameters of the wild-type and tetramer interface mutants are almost identical. However, for the dimer interface mutants, the first transition of the urea unfolding curves shift towards a lower urea concentration, and the unfolding intermediate exist at a lower urea concentration. Third, for tetrameric WT c-NADP-ME, the enzyme is first dissociated from a tetramer to dimers before the 2 M urea treatment, and the dimers then dissociated into monomers before the 2.5 M urea treatment. With a dimeric tetramer interface mutant (H142A/D568A), the dimer completely dissociated into monomers after a 2.5 M urea treatment, while for a dimeric dimer interface mutant (H51A/D90A), the dimer completely dissociated into monomers after a 1.5 M urea treatment, indicating that the interactions of c-NADP-ME at the dimer interface are truly stronger than at the tetramer interface. Thus, this study provides a reasonable explanation for why malic enzymes need to assemble as a dimer of dimers.

  6. Biophysical characterization of the dimer and tetramer interface interactions of the human cytosolic malic enzyme.

    Directory of Open Access Journals (Sweden)

    Sujithkumar Murugan

    Full Text Available The cytosolic NADP(+-dependent malic enzyme (c-NADP-ME has a dimer-dimer quaternary structure in which the dimer interface associates more tightly than the tetramer interface. In this study, the urea-induced unfolding process of the c-NADP-ME interface mutants was monitored using fluorescence and circular dichroism spectroscopy, analytical ultracentrifugation and enzyme activities. Here, we demonstrate the differential protein stability between dimer and tetramer interface interactions of human c-NADP-ME. Our data clearly demonstrate that the protein stability of c-NADP-ME is affected predominantly by disruptions at the dimer interface rather than at the tetramer interface. First, during thermal stability experiments, the melting temperatures of the wild-type and tetramer interface mutants are 8-10°C higher than those of the dimer interface mutants. Second, during urea denaturation experiments, the thermodynamic parameters of the wild-type and tetramer interface mutants are almost identical. However, for the dimer interface mutants, the first transition of the urea unfolding curves shift towards a lower urea concentration, and the unfolding intermediate exist at a lower urea concentration. Third, for tetrameric WT c-NADP-ME, the enzyme is first dissociated from a tetramer to dimers before the 2 M urea treatment, and the dimers then dissociated into monomers before the 2.5 M urea treatment. With a dimeric tetramer interface mutant (H142A/D568A, the dimer completely dissociated into monomers after a 2.5 M urea treatment, while for a dimeric dimer interface mutant (H51A/D90A, the dimer completely dissociated into monomers after a 1.5 M urea treatment, indicating that the interactions of c-NADP-ME at the dimer interface are truly stronger than at the tetramer interface. Thus, this study provides a reasonable explanation for why malic enzymes need to assemble as a dimer of dimers.

  7. Non-Mendelian transmission in a human developmental disorder: split hand/split foot.

    OpenAIRE

    Jarvik, G. P.; Patton, M. A.; Homfray, T.; Evans, J. P.

    1994-01-01

    The study of Mendelian disorders that do not meet some Mendelian expectations has led to an increased understanding of such previously obscure genetic phenomena as anticipation. Split hand/split foot (SHSF), a human developmental malformation, demonstrates such distinctive genetic features as reduced penetrance and variable expressivity. In this study, new pedigrees with defined ascertainment confirm the existence of non-Mendelian transmission characterized by the overtransmission of SHSF fro...

  8. Splitting, splitting and splitting again: A brief history of the development of regional government in Indonesia since independence

    Directory of Open Access Journals (Sweden)

    Anne Booth

    2011-04-01

    Full Text Available The paper reviews the changes in the structure and role of provincial and sub-provincial governments in Indonesia since independence. Particular attention is paid to the process of splitting both provinces and districts (kabupaten and kota into smaller units. The paper points out that this process has been going on since the 1950s, but has accelerated in the post-Soeharto era. The paper examines why the splitting of government units has occurred in some parts of the Outer Islands to a much greater extent than in Java, and also examines the implications of developments since 1999 for the capacity of local government units to deliver basic services such as health and education.

  9. Liposomes of dimeric artesunate phospholipid: A combination of dimerization and self-assembly to combat malaria.

    Science.gov (United States)

    Ismail, Muhammad; Ling, Longbing; Du, Yawei; Yao, Chen; Li, Xinsong

    2018-05-01

    Artemisinin and its derivatives are highly effective drugs in the treatment of P. falciparum malaria. However, their clinical applications face challenges because of short half-life, poor bioavailability and growing drug resistance. In this article, novel dimeric artesunate phospholipid (Di-ART-GPC) based liposomes were developed by combination of dimerization and self-assembly to address these shortcomings. Firstly, Di-ART-GPC conjugate was synthesized by a facile esterification of artesunate (ART) and glycerophosphorylcholine (GPC) and confirmed by MS, 1 H NMR and 13 C NMR. The conjugate was then assembled to form liposomes without excipient by thin film hydration method. The assembled Di-ART-GPC liposomes have typical multilamellar vesicle structure with bilayer morphology as determined by transmission electron microscopy (TEM) and cryogenic electron microscopy (cryo-EM). Moreover, the liposomes displayed an average hydrodynamic diameter of 190 nm and negative zeta potential at -20.35 mV as determined by Zetasizer. The loading capacity of ART was calculated approximately 77.6% by weight with this liposomal formulation after a simple calculation. In vitro drug release and degradation results showed that the Di-ART-GPC liposomes were stable in neutral physiological conditions but effectively degraded to release parent ART in simulated weakly acidic microenvironment. In vivo pharmacokinetics study revealed that Di-ART-GPC liposomes and conjugate have longer retention half-life in bloodstream. Importantly, Di-ART-GPC liposomes (IC 50 0.39 nM) and the conjugate (IC 50 1.90 nM) demonstrated excellent in vitro antiplasmodial activities without causing hemolysis of erythrocytes, which were superior to free ART (IC 50 5.17 nM) and conventional ART-loaded liposomes (IC 50 3.13 nM). Furthermore, the assembled liposomes resulted in enhanced parasites killing in P. berghei-infected mice in vivo with delayed recrudescence and improved survivability

  10. Split mandrel versus split sleeve coldworking: Dual methods for extending the fatigue life of metal structures

    Science.gov (United States)

    Rodman, Geoffrey A.; Creager, Matthew

    1994-01-01

    It is common practice to use split sleeve coldworking of fastener holes as a means of extending the fatigue life of metal structures. In search of lower manufacturing costs, the aerospace industry is examining the split mandrel (sleeveless) coldworking process as an alternative method of coldworking fastener holes in metal structures. The split mandrel process (SpM) significantly extends the fatigue life of metal structures through the introduction of a residual compressive stress in a manner that is very similar to the split sleeve system (SpSl). Since the split mandrel process is significantly less expensive than the split sleeve process and more adaptable to robotic automation, it will have a notable influence upon other new manufacture of metal structures which require coldworking a significant number of holes, provided the aerospace community recognizes that the resulting residual stress distributions and fatigue life improvement are the same for both processes. Considerable testing has validated the correctness of that conclusion. The findings presented in this paper represent the results of an extensive research and development program, comprising data collected from over 400 specimens fabricated from 2024-T3 and 7075-T651 aluminum alloys in varied configurations, which quantify the benefits (fatigue enhancement and cost savings) of automating a sleeveless coldworking system.

  11. Larger yield of cyclobutane dimers than 8-oxo-7,8-dihydroguanine in the DNA of UVA-irradiated human skin cells

    International Nuclear Information System (INIS)

    Courdavault, Sophie; Baudouin, Caroline; Charveron, Marie; Favier, Alain; Cadet, Jean; Douki, Thierry

    2004-01-01

    Exposure to solar ultraviolet light is the major cause of most skin cancers. While the genotoxic properties of UVB radiation are now well understood, the DNA damaging processes triggered by less energetic but more abundant UVA photons remain to be elucidated. Evidence has been provided for the induction of oxidative lesions to cellular DNA including strand breaks and 8-oxo-7,8-dihydro-2'-deoxyguanosine (8-oxodGuo). Formation of cyclobutane pyrimidine dimers (CPDs) has also been reported, mostly in rodent cells. In order to gain insights into the relevance of the latter photoproducts in UVA-mutagenesis of human skin, we quantified the level of 8-oxodGuo and CPDs within primary cultures of normal fibroblasts and keratinocytes using specific chromatographic assays. The yield of formation of CPDs was found to be higher than that of 8-oxodGuo in both cell types. In addition, CPDs were mostly TT derivatives, and neither (6-4) photoproducts nor Dewar valence isomers were detected. These observations are reminiscent of results obtained in rodent cells and suggest that a photosensitized triplet energy transfer occurs and that this reaction is more efficient than photooxidation of DNA components. The predominant formation of CPDs with respect to oxidative damage within normal human skin cells exposed to UVA radiation should be taken into account in photoprotection strategies

  12. Larger yield of cyclobutane dimers than 8-oxo-7,8-dihydroguanine in the DNA of UVA-irradiated human skin cells

    Energy Technology Data Exchange (ETDEWEB)

    Courdavault, Sophie [Laboratoire Lesions des Acides Nucleiques, Service de Chimie Inorganique et Biologique, CEA/DSM/Departement de Recherche Fondamentale sur la Matiere Condensee, CEA-Grenoble, 17, avenue des Martyrs, 38054 Grenoble Cedex 9 (France); Baudouin, Caroline [Institut de Recherche Pierre Fabre, Laboratoire de Biologie Cellulaire, Toulouse (France); Charveron, Marie [Institut de Recherche Pierre Fabre, Laboratoire de Biologie Cellulaire, Toulouse (France); Favier, Alain [Laboratoire Lesions des Acides Nucleiques, Service de Chimie Inorganique et Biologique, CEA/DSM/Departement de Recherche Fondamentale sur la Matiere Condensee, CEA-Grenoble, 17, avenue des Martyrs, 38054 Grenoble Cedex 9 (France); Cadet, Jean [Laboratoire Lesions des Acides Nucleiques, Service de Chimie Inorganique et Biologique, CEA/DSM/Departement de Recherche Fondamentale sur la Matiere Condensee, CEA-Grenoble, 17, avenue des Martyrs, 38054 Grenoble Cedex 9 (France); Douki, Thierry [Laboratoire Lesions des Acides Nucleiques, Service de Chimie Inorganique et Biologique, CEA/DSM/Departement de Recherche Fondamentale sur la Matiere Condensee, CEA-Grenoble, 17, avenue des Martyrs, 38054 Grenoble Cedex 9 (France)]. E-mail: tdouki@cea.fr

    2004-11-22

    Exposure to solar ultraviolet light is the major cause of most skin cancers. While the genotoxic properties of UVB radiation are now well understood, the DNA damaging processes triggered by less energetic but more abundant UVA photons remain to be elucidated. Evidence has been provided for the induction of oxidative lesions to cellular DNA including strand breaks and 8-oxo-7,8-dihydro-2'-deoxyguanosine (8-oxodGuo). Formation of cyclobutane pyrimidine dimers (CPDs) has also been reported, mostly in rodent cells. In order to gain insights into the relevance of the latter photoproducts in UVA-mutagenesis of human skin, we quantified the level of 8-oxodGuo and CPDs within primary cultures of normal fibroblasts and keratinocytes using specific chromatographic assays. The yield of formation of CPDs was found to be higher than that of 8-oxodGuo in both cell types. In addition, CPDs were mostly TT derivatives, and neither (6-4) photoproducts nor Dewar valence isomers were detected. These observations are reminiscent of results obtained in rodent cells and suggest that a photosensitized triplet energy transfer occurs and that this reaction is more efficient than photooxidation of DNA components. The predominant formation of CPDs with respect to oxidative damage within normal human skin cells exposed to UVA radiation should be taken into account in photoprotection strategies.0.

  13. 5-(2-amimo-4-styryl pyrimidine-4-yl-4-methoxybenzofuran-6-ol

    Directory of Open Access Journals (Sweden)

    Atteyat A Labib

    2013-05-01

    Full Text Available This study describes the organic synthesis of 5-(2-amimo-4-styryl pyrimidine-4-yl-4-methoxy benzofuran-6-ol (SPBF as an example of a benzofuran derivative used as a new series of amyloid imaging agents. These benzofuran derivatives may be useful amyloid imaging agents for detecting B-amyloid plagues in the brain of Alzheimer’s disease. The precursor is 1-[6-hydroxy-4-methoxybenzofuran-5-yl]-phenyl butadiene ketone, which react with guanidine hydrochloride. The purification process was done via crystallization using solvent ethanol. The overall yield was 75% and the structure of the synthesized compound was confirmed by correct analytical and spectral data. Also, The synthesized compound was labeled with radioactive iodine -125 via electrophilic substitution reaction, in the presence of iodogen as an oxidizing agent, the labeling process was carried out at 95oC for 20min. The radiochemical yield was determined by using a thin layer chromatography and the yield was equal to 80%. Preliminary an in-vivo study examined normal mice after intravenous injection through the tail vein and the data showed the labeling compound was quickly cleared from most body organs. The radioiodinated compound showed high brain uptake.The results of this study suggest that radioiodinated (SPBF may be useful as a brain imaging agents.

  14. Isomeric signatures in the fragmentation of pyridazine and pyrimidine induced by fast ion impact

    Energy Technology Data Exchange (ETDEWEB)

    Wolff, Wania, E-mail: wania@if.ufrj.br; Luna, Hugo; Montenegro, Eduardo C. [Instituto de Física, Universidade Federal do Rio de Janeiro, 21941-972 Rio de Janeiro, RJ (Brazil)

    2015-07-28

    We present fast proton impact induced fragmentations of pyrimidine and pyridazine as an experimental resource to investigate isomeric signatures. Major isomeric imprints are identified for few fragment ions and differences of more than an order of magnitude for the cross sections of fragments of the same mass were measured. The observation of the molecular structure of these isomers gives no apparent indication for the reasons for such substantial differences. It is verified that the simple displacement of the position of one nitrogen atom strongly inhibits or favors the production of some ionic fragment species. The dependency of the fragmentation cross sections on the proton impact energy, investigated by means of time of flight mass spectroscopy and of a model calculation based in first order perturbation theory, allows us to disentangle the complex collision dynamics of the ionic fragments. The proton-induced fragmentation discriminates rather directly the association between a molecular orbital ionization and the fragment-ions creation and abundance, as well as how the redistribution of the energy imparted to the molecules takes place, triggering not only single but also double vacancy and leads to specific fragmentation pathways.

  15. Osmium-Based Pyrimidine Contrast Tags for Enhanced Nanopore-Based DNA Base Discrimination.

    Directory of Open Access Journals (Sweden)

    Robert Y Henley

    Full Text Available Nanopores are a promising platform in next generation DNA sequencing. In this platform, an individual DNA strand is threaded into nanopore using an electric field, and enzyme-based ratcheting is used to move the strand through the detector. During this process the residual ion current through the pore is measured, which exhibits unique levels for different base combinations inside the pore. While this approach has shown great promise, accuracy is not optimal because the four bases are chemically comparable to one another, leading to small differences in current obstruction. Nucleobase-specific chemical tagging can be a viable approach to enhancing the contrast between different bases in the sequence. Herein we show that covalent modification of one or both of the pyrimidine bases by an osmium bipyridine complex leads to measureable differences in the blockade amplitudes of DNA molecules. We qualitatively determine the degree of osmylation of a DNA strand by passing it through a solid-state nanopore, and are thus able to gauge T and C base content. In addition, we show that osmium bipyridine reacts with dsDNA, leading to substantially different current blockade levels than exhibited for bare dsDNA. This work serves as a proof of principle for nanopore sequencing and mapping via base-specific DNA osmylation.

  16. New prodrugs of two pyrimidine acyclic nucleoside phosphonates: Synthesis and antiviral activity.

    Science.gov (United States)

    Krečmerová, Marcela; Dračínský, Martin; Snoeck, Robert; Balzarini, Jan; Pomeisl, Karel; Andrei, Graciela

    2017-09-01

    New 2,4-diamino-6-[2-(phosphonomethoxy)ethoxy]pyrimidine (PMEO-DAPy) and 1-[2-(phosphonomethoxy)ethyl]-5-azacytosine (PME-5-azaC) prodrugs were prepared with a pro-moiety consisting of carbonyloxymethyl esters (POM, POC), alkoxyalkyl esters, amino acid phosphoramidates and/or tyrosine. The activity of the prodrugs was evaluated in vitro against different virus families. None of the synthesized prodrugs demonstrated activity against RNA viruses but some of them proved active against herpesviruses [including herpes simplex virus (HSV), varicella-zoster virus (VZV), and human cytomegalovirus (HCMV)]. The bis(POC) and the bis(amino acid) phosphoramidate prodrugs of PMEO-DAPy inhibited herpesvirus replication at lower doses than the parent compound although the selectivity against HSV and VZV was only slightly improved compared to PMEO-DAPy. The mono-octadecyl ester of PME-5-azaC emerged as the most potent and selective PME-5-azaC prodrug against HSV, VZV and HCMV with EC 50 's of 0.15-1.12µM while PME-5-azaC only had marginal anti-herpesvirus activity. Although the bis(hexadecylamido-l-tyrosyl) and the bis(POM) esters of PME-5-azaC were also very potent anti-herpesvirus drugs, these were less selective than the mono-octadecyl ester prodrug. Copyright © 2017 Elsevier Ltd. All rights reserved.

  17. A novel pyrimidin-like plant activator stimulates plant disease resistance and promotes growth.

    Directory of Open Access Journals (Sweden)

    Tie-Jun Sun

    Full Text Available Plant activators are chemicals that induce plant defense responses to a broad spectrum of pathogens. Here, we identified a new potential plant activator, 5-(cyclopropylmethyl-6-methyl-2-(2-pyridylpyrimidin-4-ol, named PPA (pyrimidin-type plant activator. Compared with benzothiadiazole S-methyl ester (BTH, a functional analog of salicylic acid (SA, PPA was fully soluble in water and increased fresh weight of rice (Oryza sativa and Arabidopsis plants at low concentrations. In addition, PPA also promoted lateral root development. Microarray data and real-time PCR revealed that PPA-treated leaves not challenged with pathogen showed up-regulation of genes related to reactive oxygen species (ROS, defenses and SA. During bacterial infection, Arabidopsis plants pretreated with PPA showed dramatically decreased disease symptoms and an earlier and stronger ROS burst, compared with plants pretreated with BTH. Microscopy revealed that H2O2 accumulated in the cytosol, plasma membrane and cell wall around intracellular bacteria, and also on the bacterial cell wall, indicating that H2O2 was directly involved in killing bacteria. The increase in ROS-related gene expression also supported this observation. Our results indicate that PPA enhances plant defenses against pathogen invasion through the plant redox system, and as a water-soluble compound that can promote plant growth, has broad potential applications in agriculture.

  18. Substituted pyrrolo[2,3-d]pyrimidines as Cryptosporidium hominis thymidylate synthase inhibitors.

    Science.gov (United States)

    Kumar, Vidya P; Frey, Kathleen M; Wang, Yiqiang; Jain, Hitesh K; Gangjee, Aleem; Anderson, Karen S

    2013-10-01

    Cryptosporidiosis, a gastrointestinal disease caused by a protozoan Cryptosporidium hominis is often fatal in immunocompromised individuals. There is little clinical data to show that the existing treatment by nitazoxanide and paromomycin is effective in immunocompromised individuals. Thymidylate synthase (TS) and dihydrofolate reductase (DHFR) are essential enzymes in the folate biosynthesis pathway and are well established as drug targets in cancer and malaria. A novel series of classical antifolates, 2-amino-4-oxo-5-substituted pyrrolo[2,3-d]pyrimidines have been evaluated as Cryptosporidium hominis thymidylate synthase (ChTS) inhibitors. Crystal structure in complex with the most potent compound, a 2'-chlorophenyl with a sulfur bridge with a Ki of 8.83±0.67 nM is discussed in terms of several Van der Waals, hydrophobic and hydrogen bond interactions with the protein residues and the substrate analog 5-fluorodeoxyuridine monophosphate. Of these interactions, two interactions with the non-conserved residues (A287 and S290) offer an opportunity to develop ChTS specific inhibitors. Compound 6 serves as a lead compound for analog design and its crystal structure provides clues for the design of ChTS specific inhibitors. Copyright © 2013 The Authors. Published by Elsevier Ltd.. All rights reserved.

  19. Glutamine domain of the chimeric protein, CAD, that initiates pyrimidine biosynthesis in mammalian cells

    International Nuclear Information System (INIS)

    Kelly, R.E.; Kim, H.; Evans, D.R.

    1986-01-01

    Glutamine dependent carbamyl phosphate synthesis, the first step in mammalian de novo pyrimidine biosynthesis, is catalyzed by a 240 kDa chimeric protein, CAD, that also has the aspartate transcarbamylase and dihydroorotase activities. The complex was found to have a separate glutaminase activity of 0.04 μmol/min/mg, that increased five fold in the presence of bicarbonate and ATP. To determine whether the glutaminase activity, which provides ammonia for carbamyl phosphate synthesis, is associated with a separate structural domain (GLN), CAD was subjected to controlled proteolysis with elastase. The glutaminase, glutamine and ammonia dependent carbamyl phosphate synthetase activities, as well as the partial reactions; carbamyl phosphate dependent ATP synthesis and bicarbonate dependent ATPase, were correlated with the concentration of the various proteolytic fragments that accumulated in the digest. While the glutamine dependent carbamyl phosphate synthetase was rapidly inactivated, the glutaminase activity was found to be very resistant to proteolysis. The glutamine binding site of CAD was also specifically modified with 6-diazo-5-oxo-L-norleucine (DON). The modification was accompanied by a loss of both glutaminase and glutamine dependent carbamyl phosphate synthetase activities. Bicarbonate and ATP increased the rate of reaction of CAD with DON, while glutamine protected against inactivation. The stoichiometry of the reaction and the identity of the modified proteolytic fragments was determined using 14 C labelled DON

  20. Photoelectrochemical water splitting: optimizing interfaces and light absorption

    NARCIS (Netherlands)

    Park, Sun-Young

    2015-01-01

    In this thesis several photoelectrochemical water splitting devices based on semiconductor materials were investigated. The aim was the design, characterization, and fabrication of solar-to-fuel devices which can absorb solar light and split water to produce hydrogen.

  1. A Regularized Algorithm for the Proximal Split Feasibility Problem

    Directory of Open Access Journals (Sweden)

    Zhangsong Yao

    2014-01-01

    Full Text Available The proximal split feasibility problem has been studied. A regularized method has been presented for solving the proximal split feasibility problem. Strong convergence theorem is given.

  2. Facile synthesis of dimer phase of coronene and its optical properties

    Energy Technology Data Exchange (ETDEWEB)

    Hayakawa, T.; Song, H.; Ishii, Y.; Kawasaki, S., E-mail: kawasaki.shinji@nitech.ac.jp [Nagoya Institute of Technology, Gokiso, Showa, Nagoya, Aichi (Japan)

    2016-07-06

    We synthesized very pure dimer phase of coronene by simple heat-treatment and subsequent sublimation purification. It was found that the dimer phase emits very bright red light under the irradiation of low energy ultra-violet light.

  3. On the Elusive Twelfth Vibrational State of Beryllium Dimer

    Czech Academy of Sciences Publication Activity Database

    Patkowski, K.; Špirko, Vladimír; Szalewicz, K.

    2009-01-01

    Roč. 326, č. 5958 (2009), s. 1382-1384 ISSN 0036-8075 Institutional research plan: CEZ:AV0Z40550506 Keywords : potential function * beryllium dimer * morphed potentials Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 29.747, year: 2009

  4. Photodissociation pathways and lifetimes of protonated peptides and their dimers

    DEFF Research Database (Denmark)

    Gopalan, Aravind; Klærke, Benedikte; Rajput, Jyoti

    2012-01-01

    rate constants also confirmed a statistical nature of the photodissociation processes in the dipeptide monomers and dimers. The classical RRKM expression gives a rate constant as an analytical function of the number of active vibrational modes in the system, estimated separately on the basis...

  5. Determining Equilibrium Constants for Dimerization Reactions from Molecular Dynamics Simulations

    NARCIS (Netherlands)

    De Jong, Djurre H.; Schafer, Lars V.; De Vries, Alex H.; Marrink, Siewert J.; Berendsen, Herman J. C.; Grubmueller, Helmut

    2011-01-01

    With today's available computer power, free energy calculations from equilibrium molecular dynamics simulations "via counting" become feasible for an increasing number of reactions. An example is the dimerization reaction of transmembrane alpha-helices. If an extended simulation of the two helices

  6. Asymmetric electron capture in HCI collisions with rare gas dimers

    Science.gov (United States)

    Matsumoto, J.; Leredde, A.; Fléchard, X.; Shiromaru, H.; Rangama, J.; Zhou, C. L.; Iskandar, W.; Guillous, S.; Hennecart, D.; Mery, A.; Gervais, B.; Cassimi, A.

    2014-04-01

    Low-energy collisions between different rare gas dimers (Ar2, Ne2) and different projectiles (O3+, Ar9+, Xe20+) show that the weight of the different fragmentation processes, Coulomb explosion and Radiative Charge Transfer, strongly depends on the projectile charge state. This result is understood in term of impact parameter from which the electrons are captured on the projectile.

  7. DNAzyme-Controlled Cleavage of Dimer and Trimer Origami Tiles.

    Science.gov (United States)

    Wu, Na; Willner, Itamar

    2016-04-13

    Dimers of origami tiles are bridged by the Pb(2+)-dependent DNAzyme sequence and its substrate or by the histidine-dependent DNAzyme sequence and its substrate to yield the dimers T1-T2 and T3-T4, respectively. The dimers are cleaved to monomer tiles in the presence of Pb(2+)-ions or histidine as triggers. Similarly, trimers of origami tiles are constructed by bridging the tiles with the Pb(2+)-ion-dependent DNAzyme sequence and the histidine-dependent DNAzyme sequence and their substrates yielding the trimer T1-T5-T4. In the presence of Pb(2+)-ions and/or histidine as triggers, the programmed cleavage of trimer proceeds. Using Pb(2+) or histidine as trigger cleaves the trimer to yield T5-T4 and T1 or the dimer T1-T5 and T4, respectively. In the presence of Pb(2+)-ions and histidine as triggers, the cleavage products are the monomer tiles T1, T5, and T4. The different cleavage products are identified by labeling the tiles with 0, 1, or 2 streptavidin labels and AFM imaging.

  8. Fe65-PTB2 Dimerization Mimics Fe65-APP Interaction

    Directory of Open Access Journals (Sweden)

    Lukas P. Feilen

    2017-05-01

    Full Text Available Physiological function and pathology of the Alzheimer’s disease causing amyloid precursor protein (APP are correlated with its cytosolic adaptor Fe65 encompassing a WW and two phosphotyrosine-binding domains (PTBs. The C-terminal Fe65-PTB2 binds a large portion of the APP intracellular domain (AICD including the GYENPTY internalization sequence fingerprint. AICD binding to Fe65-PTB2 opens an intra-molecular interaction causing a structural change and altering Fe65 activity. Here we show that in the absence of the AICD, Fe65-PTB2 forms a homodimer in solution and determine its crystal structure at 2.6 Å resolution. Dimerization involves the unwinding of a C-terminal α-helix that mimics binding of the AICD internalization sequence, thus shielding the hydrophobic binding pocket. Specific dimer formation is validated by nuclear magnetic resonance (NMR techniques and cell-based analyses reveal that Fe65-PTB2 together with the WW domain are necessary and sufficient for dimerization. Together, our data demonstrate that Fe65 dimerizes via its APP interaction site, suggesting that besides intra- also intermolecular interactions between Fe65 molecules contribute to homeostatic regulation of APP mediated signaling.

  9. Dimeric Complexes of Tryptophan with M2+ Metal Ions

    NARCIS (Netherlands)

    Dunbar, R. C.; Steill, J. D.; Polfer, N. C.; Oomens, J.

    2009-01-01

    IRMPD spectroscopy using the FELIX free electron laser and a Fourier transform ICR mass spectrometer was used to characterize the structures of electrosprayed dimer complexes M(2+)Trp(2) of tryptophan with a series of eight doubly charged metal ions, including alkaline earths Ca, Sr, and Ba, and

  10. One-pot Solvent-free Catalytic Dimerization Reaction of ...

    Indian Academy of Sciences (India)

    Abstract. In this study, we report a smooth one-pot, solvent-free catalytic dimerization of phenylacetylene. (1) to 1-phenylnaphthalene (2) by Cu/C at room temperature in good yield (∼100%). In the computational study, the structure of the 1-phenylnaphthalene was optimized by DFT-B3LYP/6-31G* method. The rotation.

  11. Cationic zinc (II) dimers and one dimensional coordination polymer ...

    Indian Academy of Sciences (India)

    Home; Journals; Journal of Chemical Sciences; Volume 126; Issue 5 ... Special issue on Chemical Crystallography Volume 126 Issue 5 September 2014 pp 1409-1415 ... These new molecules, dimers and polymer, were characterized by FT-IR, NMR, UV-vis, fluorescent and single crystal X-ray diffraction techniques.

  12. Spectroscopic observation and structure of CS2 dimer

    Science.gov (United States)

    Rezaei, M.; Norooz Oliaee, J.; Moazzen-Ahmadi, N.; McKellar, A. R. W.

    2011-04-01

    Infrared spectra of the CS2 dimer are observed in the region of the CS2 ν3 fundamental band (˜1535 cm-1) using a tunable diode laser spectrometer. The weakly bound complex is formed in a pulsed supersonic slit-jet expansion of a dilute gas mixture of carbon disulfide in helium. Contrary to the planar slipped-parallel geometry previously observed for (CO2)2, (N2O)2, and (OCS)2, the CS2 dimer exhibits a cross-shaped structure with D2d symmetry. Two bands were observed and analyzed: the fundamental (C-S asymmetric stretch) and a combination involving this mode plus an intermolecular vibration. In both cases, the rotational structure corresponds to a perpendicular (ΔK = ±1) band of a symmetric rotor molecule. The intermolecular center of mass separation (C-C distance) is determined to be 3.539(7) Å. Thanks to symmetry, this is the only parameter required to characterize the structure, if the monomer geometry is assumed to remain unchanged in the dimer. From the band centers of the fundamental and combination band an intermolecular frequency of 10.96 cm-1 is obtained, which we assign as the torsional bending mode. This constitutes the first high resolution spectroscopic investigation of CS2 dimer.

  13. Emergence of biaxial nematic phases in solutions of semiflexible dimers

    Science.gov (United States)

    Vaghela, Arvin; Teixeira, Paulo I. C.; Terentjev, Eugene M.

    2017-10-01

    We investigate the isotropic, uniaxial nematic and biaxial nematic phases, and the transitions between them, for a model lyotropic mixture of flexible molecules consisting of two rigid rods connected by a spacer with variable bending stiffness. We apply density-functional theory within the Onsager approximation to describe strictly excluded-volume interactions in this athermal model and to self-consistently find the orientational order parameters dictated by its complex symmetry, as functions of the density. Earlier work on lyotropic ordering of rigid bent-rod molecules is reproduced and extended to show explicitly the continuous phase transition at the Landau point, at a critical bend angle of 36∘. For flexible dimers with no intrinsic biaxiality, we find that a biaxial nematic phase can nevertheless form at a sufficiently high density and low bending stiffness. For bending stiffness κ >0.86 kBT , this biaxial phase manifests as dimer bending fluctuations occurring preferentially in one plane. When the dimers are more flexible, κ the modal shape of the fluctuating dimer is a V with an acute opening angle, and one of the biaxial order parameters changes sign, indicating a rotation of the directors. These two regions are separated by a narrow strip of uniaxial nematic in the phase diagram, which we generate in terms of the spacer stiffness and particle density.

  14. Characteristics of thymine dimer excision from xeroderma pigmentosum chromatin

    International Nuclear Information System (INIS)

    Fujiwara, Y.; Kano, Y.

    1983-01-01

    We investigated thymine dimer excision from xeroderma pigmentosum (XP) chromatin in the cell-free reconstruction system. The normal-cell extract performed specific dimer excision from native chromatin and DNA isolated from 100 J/m 2 -irradiated cells. Such an excision in vitro was rapid and required high concentrations of extract. The extracts of XP group A, C and G cells were unable to excise from their own native-chromatin, but capable of excising from chromatin deprived of loosely bound nonhistone proteins with 0.35 M NaCl, as were from purified DNA. Thus, group A, C and G cells are most likely to be defective in the specific XP factors facilitating the excising activity under multicomponent regulation at the chromatin level. Further, either of group A, C and G extracts successfully complemented the native chromatin of the alternative groups. Uniquely, the XP group D extract excised dimers from native chromatin in the normal fashion under the condition. These results suggest that XP group A, C, D and G cells examined may not be defective in the dimer specific endonuclease and exonuclease per se. 19 references, 3 figures, 2 tables

  15. Core-to-core dimers forming switchable mesophase

    Czech Academy of Sciences Publication Activity Database

    Horčic, M.; Svoboda, J.; Novotná, Vladimíra; Pociecha, D.; Gorecka, E.

    2017-01-01

    Roč. 53, č. 18 (2017), s. 2721-2724 ISSN 1359-7345 R&D Projects: GA ČR GA15-02843S Institutional support: RVO:68378271 Keywords : liquid crystals * bent-core mesogens * dimers Subject RIV: JJ - Other Materials OBOR OECD: Nano-materials (production and properties) Impact factor: 6.319, year: 2016

  16. Plasma D-dimer concentration in patients with systemic sclerosis

    Directory of Open Access Journals (Sweden)

    Montagnana Martina

    2006-01-01

    Full Text Available Abstract Background Systemic sclerosis (SSc is an autoimmune disorder of the connective tissue characterized by widespread vascular lesions and fibrosis. Little is known so far on the activation of the hemostatic and fibrinolytic systems in SSc, and most preliminary evidences are discordant. Methods To verify whether SSc patients might display a prothrombotic condition, plasma D-dimer was assessed in 28 consecutive SSc patients and in 33 control subjects, matched for age, sex and environmental habit. Results and discussion When compared to healthy controls, geometric mean and 95% confidence interval (IC95% of plasma D-dimer were significantly increased in SSc patients (362 ng/mL, IC 95%: 361–363 ng/mL vs 229 ng/mL, IC95%: 228–231 ng/mL, p = 0.005. After stratifying SSc patients according to disease subset, no significant differences were observed between those with limited cutaneous pattern and controls, whereas patients with diffuse cutaneous pattern displayed substantially increased values. No correlation was found between plasma D-dimer concentration and age, sex, autoantibody pattern, serum creatinine, erythrosedimentation rate, nailfold videocapillaroscopic pattern and pulmonary involvement. Conclusion We demonstrated that SSc patients with diffuse subset are characterized by increased plasma D-dimer values, reflecting a potential activation of both the hemostatic and fibrinolytic cascades, which might finally predispose these patients to thrombotic complications.

  17. Identification of Trimer and Dimer of 4-hydroxy-3-methoxy ...

    African Journals Online (AJOL)

    The effect of intermolecular hydrogen bonding on the molecular structure of vanillin has been studied using negative ion chemical ionization (NICl) mass spectrometry methods. The [Trimer-H2O] and [Dimer-H2O] were observed at m/z 438 and 286 respectively in NICl (CH4) mass spectrum of vanillin. The NICl (Cl) mass ...

  18. Designer interface peptide grafts target estrogen receptor alpha dimerization

    International Nuclear Information System (INIS)

    Chakraborty, S.; Asare, B.K.; Biswas, P.K.; Rajnarayanan, R.V.

    2016-01-01

    The nuclear transcription factor estrogen receptor alpha (ERα), triggered by its cognate ligand estrogen, regulates a variety of cellular signaling events. ERα is expressed in 70% of breast cancers and is a widely validated target for anti-breast cancer drug discovery. Administration of anti-estrogen to block estrogen receptor activation is still a viable anti-breast cancer treatment option but anti-estrogen resistance has been a significant bottle-neck. Dimerization of estrogen receptor is required for ER activation. Blocking ERα dimerization is therefore a complementary and alternative strategy to combat anti-estrogen resistance. Dimer interface peptide “I-box” derived from ER residues 503–518 specifically blocks ER dimerization. Recently using a comprehensive molecular simulation we studied the interaction dynamics of ERα LBDs in a homo-dimer. Based on this study, we identified three interface recognition peptide motifs LDKITDT (ERα residues 479–485), LQQQHQRLAQ (residues 497–506), and LSHIRHMSNK (residues 511–520) and reported the suitability of using LQQQHQRLAQ (ER 497–506) as a template to design inhibitors of ERα dimerization. Stability and self-aggregation of peptide based therapeutics poses a significant bottle-neck to proceed further. In this study utilizing peptide grafted to preserve their pharmacophoric recognition motif and assessed their stability and potential to block ERα mediated activity in silico and in vitro. The Grafted peptides blocked ERα mediated cell proliferation and viability of breast cancer cells but did not alter their apoptotic fate. We believe the structural clues identified in this study can be used to identify novel peptidometics and small molecules that specifically target ER dimer interface generating a new breed of anti-cancer agents. - Highlights: • Designer peptide grafts retain core molecular recognition motif during MD simulations. • Designer peptide grafts with Poly-ALA helix form stable

  19. Designer interface peptide grafts target estrogen receptor alpha dimerization

    Energy Technology Data Exchange (ETDEWEB)

    Chakraborty, S. [Laboratory of Computational Biophysics & Bioengineering, Department of Physics, Tougaloo College, Tougaloo, MS 39174 (United States); Asare, B.K. [Department of Pharmacology and Toxicology, University of Buffalo, Buffalo, NY 14214 (United States); Biswas, P.K., E-mail: pbiswas@tougaloo.edu [Laboratory of Computational Biophysics & Bioengineering, Department of Physics, Tougaloo College, Tougaloo, MS 39174 (United States); Rajnarayanan, R.V., E-mail: rajendra@buffalo.edu [Department of Pharmacology and Toxicology, University of Buffalo, Buffalo, NY 14214 (United States)

    2016-09-09

    The nuclear transcription factor estrogen receptor alpha (ERα), triggered by its cognate ligand estrogen, regulates a variety of cellular signaling events. ERα is expressed in 70% of breast cancers and is a widely validated target for anti-breast cancer drug discovery. Administration of anti-estrogen to block estrogen receptor activation is still a viable anti-breast cancer treatment option but anti-estrogen resistance has been a significant bottle-neck. Dimerization of estrogen receptor is required for ER activation. Blocking ERα dimerization is therefore a complementary and alternative strategy to combat anti-estrogen resistance. Dimer interface peptide “I-box” derived from ER residues 503–518 specifically blocks ER dimerization. Recently using a comprehensive molecular simulation we studied the interaction dynamics of ERα LBDs in a homo-dimer. Based on this study, we identified three interface recognition peptide motifs LDKITDT (ERα residues 479–485), LQQQHQRLAQ (residues 497–506), and LSHIRHMSNK (residues 511–520) and reported the suitability of using LQQQHQRLAQ (ER 497–506) as a template to design inhibitors of ERα dimerization. Stability and self-aggregation of peptide based therapeutics poses a significant bottle-neck to proceed further. In this study utilizing peptide grafted to preserve their pharmacophoric recognition motif and assessed their stability and potential to block ERα mediated activity in silico and in vitro. The Grafted peptides blocked ERα mediated cell proliferation and viability of breast cancer cells but did not alter their apoptotic fate. We believe the structural clues identified in this study can be used to identify novel peptidometics and small molecules that specifically target ER dimer interface generating a new breed of anti-cancer agents. - Highlights: • Designer peptide grafts retain core molecular recognition motif during MD simulations. • Designer peptide grafts with Poly-ALA helix form stable

  20. Multiple Rabi Splittings under Ultrastrong Vibrational Coupling.

    Science.gov (United States)

    George, Jino; Chervy, Thibault; Shalabney, Atef; Devaux, Eloïse; Hiura, Hidefumi; Genet, Cyriaque; Ebbesen, Thomas W

    2016-10-07

    From the high vibrational dipolar strength offered by molecular liquids, we demonstrate that a molecular vibration can be ultrastrongly coupled to multiple IR cavity modes, with Rabi splittings reaching 24% of the vibration frequencies. As a proof of the ultrastrong coupling regime, our experimental data unambiguously reveal the contributions to the polaritonic dynamics coming from the antiresonant terms in the interaction energy and from the dipolar self-energy of the molecular vibrations themselves. In particular, we measure the opening of a genuine vibrational polaritonic band gap of ca. 60 meV. We also demonstrate that the multimode splitting effect defines a whole vibrational ladder of heavy polaritonic states perfectly resolved. These findings reveal the broad possibilities in the vibrational ultrastrong coupling regime which impact both the optical and the molecular properties of such coupled systems, in particular, in the context of mode-selective chemistry.

  1. Splitting of high power, cw proton beams

    Directory of Open Access Journals (Sweden)

    Alberto Facco

    2007-09-01

    Full Text Available A simple method for splitting a high power, continuous wave (cw proton beam in two or more branches with low losses has been developed in the framework of the EURISOL (European Isotope Separation On-Line Radioactive Ion Beam Facility design study. The aim of the system is to deliver up to 4 MW of H^{-} beam to the main radioactive ion beam production target, and up to 100 kW of proton beams to three more targets, simultaneously. A three-step method is used, which includes magnetic neutralization of a fraction of the main H^{-} beam, magnetic splitting of H^{-} and H^{0}, and stripping of H^{0} to H^{+}. The method allows slow raising and individual fine adjustment of the beam intensity in each branch.

  2. Meshed split skin graft for extensive vitiligo

    Directory of Open Access Journals (Sweden)

    Srinivas C

    2004-05-01

    Full Text Available A 30 year old female presented with generalized stable vitiligo involving large areas of the body. Since large areas were to be treated it was decided to do meshed split skin graft. A phototoxic blister over recipient site was induced by applying 8 MOP solution followed by exposure to UVA. The split skin graft was harvested from donor area by Padgett dermatome which was meshed by an ampligreffe to increase the size of the graft by 4 times. Significant pigmentation of the depigmented skin was seen after 5 months. This procedure helps to cover large recipient areas, when pigmented donor skin is limited with minimal risk of scarring. Phototoxic blister enables easy separation of epidermis thus saving time required for dermabrasion from recipient site.

  3. Timelike single-logarithm-resummed splitting functions

    International Nuclear Information System (INIS)

    Albino, S.; Bolzoni, P.; Kniehl, B.A.; Kotikov, A.V.; Joint Inst. of Nuclear Research, Moscow

    2011-08-01

    We calculate the single logarithmic contributions to the quark singlet and gluon matrix of timelike splitting functions at all orders in the modified minimal-subtraction (MS) scheme. We fix two of the degrees of freedom of this matrix from the analogous results in the massive-gluon regularization scheme by using the relation between that scheme and the MS scheme. We determine this scheme transformation from the double logarithmic contributions to the timelike splitting functions and the coefficient functions of inclusive particle production in e + e - annihilation now available in both schemes. The remaining two degrees of freedom are fixed by reasonable physical assumptions. The results agree with the fixed-order results at next-to-next-to-leading order in the literature. (orig.)

  4. Solar Water Splitting Using Semiconductor Photocatalyst Powders

    KAUST Repository

    Takanabe, Kazuhiro

    2015-07-01

    Solar energy conversion is essential to address the gap between energy production and increasing demand. Large scale energy generation from solar energy can only be achieved through equally large scale collection of the solar spectrum. Overall water splitting using heterogeneous photocatalysts with a single semiconductor enables the direct generation of H from photoreactors and is one of the most economical technologies for large-scale production of solar fuels. Efficient photocatalyst materials are essential to make this process feasible for future technologies. To achieve efficient photocatalysis for overall water splitting, all of the parameters involved at different time scales should be improved because the overall efficiency is obtained by the multiplication of all these fundamental efficiencies. Accumulation of knowledge ranging from solid-state physics to electrochemistry and a multidisciplinary approach to conduct various measurements are inevitable to be able to understand photocatalysis fully and to improve its efficiency.

  5. Atom beams split by gentle persuasion

    International Nuclear Information System (INIS)

    Pool, R.

    1994-01-01

    Two different research teams have taken a big step toward atom interferometry. They have succeeded in splitting atomic beams by using atoms in spin states that neither absorb nor reemit laser light. By proper adjustment of experimental conditions, atoms are changed from one spin state to another, without passing through the intermediary excited state. The atoms in essence absorb momentum from the laser photons, without absorption or emission of photons. The change in momentum deflects atoms in the proper spin state

  6. On split Lie triple systems II

    Indian Academy of Sciences (India)

    In the present paper we extend these results to arbitrary split Lie triple systems with no restrictions on their 0-root spaces. Author Affiliations. Antonio J Calderón Martín1 M Forero Piulestán1. Departamento de Matemáticas, Universidad de Cádiz, 11510 Puerto Real, Cádiz, Spain. Dates. Manuscript received: 24 June 2009 ...

  7. 2-Ethynylpyridine dimers: IR spectroscopic and computational study

    Science.gov (United States)

    Bakarić, Danijela; Spanget-Larsen, Jens

    2018-04-01

    2-ethynylpyridine (2-EP) presents a multifunctional system capable of participation in hydrogen-bonded complexes utilizing hydrogen bond donating (tbnd Csbnd H, Aryl-H) and hydrogen bond accepting functions (N-atom, Ctbnd C and pyridine π-systems). In this work, IR spectroscopy and theoretical calculations are used to study possible 2-EP dimer structures as well as their distribution in an inert solvent such as tetrachloroethene. Experimentally, the tbnd Csbnd H stretching vibration of the 2-EP monomer absorbs close to 3300 cm-1, whereas a broad band with maximum around 3215 cm-1 emerges as the concentration rises, indicating the formation of hydrogen-bonded complexes involving the tbnd Csbnd H moiety. The Ctbnd C stretching vibration of monomer 2-EP close to 2120 cm-1 is, using derivative spectroscopy, resolved from the signals of the dimer complexes with maximum around 2112 cm-1. Quantum chemical calculations using the B3LYP + D3 model with counterpoise correction predict that the two most stable dimers are of the π-stacked variety, closely followed by dimers with intermolecular tbnd Csbnd H⋯N hydrogen bonding; the predicted red shifts of the tbnd Csbnd H stretching wavenumbers due to hydrogen bonding are in the range 54-120 cm-1. No species with obvious hydrogen bonding involving the Ctbnd C or pyridine π-systems as acceptors are predicted. Dimerization constant at 25 °C is estimated to be K2 = 0.13 ± 0.01 mol-1 dm3.

  8. Biological activity and dimerization state of modified phytochrome A proteins.

    Directory of Open Access Journals (Sweden)

    Peng Liu

    Full Text Available To assess potential physical interactions of type I phyA with the type II phyB-phyE phytochromes in vivo, transgenes expressing fusion gene forms of phyA were introduced into the Arabidopsis phyA mutant background. When a single c-Myc (myc epitope is added to either the N- or C-terminus of phyA, the constructs completely complement phyA mutant phenotypes. However, addition of larger tags, such as six consecutive myc epitopes or the yellow fluorescent protein sequence, result in fusion proteins that show reduced activity. All the tagged phyA proteins migrate as dimers on native gels and co-immunoprecipitation reveals no binding interaction of phyA to any of the type II phys in the dark or under continuous far-red light. Dimers of the phyA 1-615 amino acid N-terminal photosensory domain (NphyA, generated in vivo with a yeast GAL4 dimerization domain and attached to a constitutive nuclear localization sequence, are expressed at a low level and, although they cause a cop phenotype in darkness and mediate a very low fluence response to pulses of FR, have no activity under continuous FR. It is concluded that type I phyA in its Pr form is present in plants predominantly or exclusively as a homodimer and does not stably interact with type II phys in a dimer-to-dimer manner. In addition, its activity in mediating response to continuous FR is sensitive to modification of its N- or C-terminus.

  9. Transonymization as Revitalization: Old Toponyms of Split

    Directory of Open Access Journals (Sweden)

    Katarina Lozić Knezović

    2017-07-01

    Full Text Available The paper deals with ancient toponyms of Split, a city in the centre of the Croatian region of Dalmatia. Along with numerous monuments of spiritual and material culture, toponyms are part of the two-thousand-year-old city’s historical heritage. Split in particular abounds with sources that provide valuable information concerning ancient toponyms. In terms of the study and preservation of toponymy, three basic sources are crucial: the living oral tradition, written records, and old charts — mostly cadastral plans. In addition to researching, recording, documenting, and publishing Split’s ancient place names through toponomastic, geographical, and town planning studies, toponymic heritage preservation is also implemented through the direct use of the names in everyday life. One of the ways of such revitalization of Split’s ancient place names is their transonymization into the category of chrematonyms, i.e. their secondary use as names of institutions, shops, restaurants, schools, sports associations and facilities, bars and coffee shops, cemeteries, and so on. The present paper provides a classification and etymological analysis of detoponymic chrematonyms of Split. The authors propose measures to raise public awareness of the historical information conveyed by the names and raise some issues for consideration regarding further study of transonymization as a means of revitalizing local toponymic tradition.

  10. Synthesis of 2-substituted 9-oxa-guanines {5-aminooxazolo[5,4-d]pyrimidin-7(6H-ones} and 9-oxa-2-thio-xanthines {5-mercaptooxazolo[5,4-d]pyrimidin-7(6H-ones}

    Directory of Open Access Journals (Sweden)

    2008-07-01

    Full Text Available Oxazolo[5,4-d]pyrimidines can be considered as 9-oxa-purine analogs of naturally occurring nucleic acid bases. Interest in this ring system has increased due to recent reports of biologically active derivatives. In particular, 5-aminooxazolo[5,4-d]pyrimidine-7(6H-ones (9-oxa-guanines have been shown to inhibit ricin. The preparation of a series of 2-substituted 5-aminooxazolo[5,4-d]pyrimidin-7(6H-ones and related 5-thio-oxazolo[5,4-d]pyrimidines is described, including analogs suitable for further elaboration employing “click” chemistry utilizing copper-catalyzed Huisgen 1,3-dipolar cycloadditions. Two of the compounds prepared were found to inhibit ricin with IC50 ca. 1–3 mM.

  11. 26 CFR 1.7872-15 - Split-dollar loans.

    Science.gov (United States)

    2010-04-01

    ...) INCOME TAXES General Actuarial Valuations § 1.7872-15 Split-dollar loans. (a) General rules—(1... split-dollar loan depend upon the relationship between the parties and upon whether the loan is a demand...-dollar demand loan is any split-dollar loan that is payable in full at any time on the demand of the...

  12. 7 CFR 51.2731 - U.S. Spanish Splits.

    Science.gov (United States)

    2010-01-01

    ... 7 Agriculture 2 2010-01-01 2010-01-01 false U.S. Spanish Splits. 51.2731 Section 51.2731... STANDARDS) United States Standards for Grades of Shelled Spanish Type Peanuts Grades § 51.2731 U.S. Spanish Splits. “U.S. Spanish Splits” consists of shelled Spanish type peanut kernels which are split or broken...

  13. Brug af D-dimer til at udelukke dyb venøs trombose i overekstremiteterne

    DEFF Research Database (Denmark)

    Ahler-Toftehøj, Hans-Ulrik; Mikkelsen, Peter

    2009-01-01

    D-dimer is often used to exclude deep venous thrombosis, primarily in the lower extremities. We describe a 38-year-old man who had deep venous thrombosis in the left vena subclavia in spite of a normal D-dimer. Only one inconclusive survey compares the value of D-dimer and upper extremity deep...

  14. Age- and sex-dependent reference intervals for D-dimer

    DEFF Research Database (Denmark)

    Haase, Christine; Joergensen, Maja; Ellervik, Christina

    2013-01-01

    A low D-dimer is commonly used to exclude venous thromboembolism in low risk patients. However, the reference intervals are poorly defined and D-dimer has been shown to increase by patient age. We aimed to establish age- and sex-dependent D-dimer reference intervals and to test the consequence of...... of different cut-off limits....

  15. Semiconductor Nanowires for Photoelectrochemical Water Splitting

    Science.gov (United States)

    Hwang, Yun Jeong

    Photolysis of water with semiconductor materials has been investigated intensely as a clean and renewable energy resource by storing solar energy in chemical bonds such as hydrogen. One-dimensional (1D) nanostructures such as nanowires can provide several advantages for photoelectrochemical (PEC) water splitting due to their high surface areas and excellent charge transport and collection efficiency. This dissertation discusses various nanowire photoelectrodes for single or dual semiconductor systems, and their linked PEC cells for self-driven water splitting. After an introduction of solar water splitting in the first chapter, the second chapter demonstrates water oxidative activities of hydrothermally grown TiO2 nanowire arrays depending on their length and surface properties. The photocurrents with TiO2 nanowire arrays approach saturation due to their poor charge collection efficiency with longer nanowires despite increased photon absorption efficiency. Epitaxial grains of rutile atomic layer deposition (ALD) shell on TiO2 nanowire increase the photocurrent density by 1.5 times due to improved charge collection efficiency especially in the short wavelength region. Chapter three compares the photocurrent density of the planar Si and Si nanowire arrays coated by anatase ALD TiO 2 thin film as a model system of a dual bandgap system. The electroless etched Si nanowire coated by ALD TiO2 (Si EENW/TiO2) shows 2.5 times higher photocurrent density due to lower reflectance and higher surface area. Also, this chapter illustrates that n-Si/n-TiO2 heterojunction is a promising structure for the photoanode application of a dual semiconductor system, since it can enhance the photocurrent density compared to p-Si/n-TiO 2 junction with the assistance of bend banding at the interface. Chapter four demonstrates the charge separation and transport of photogenerated electrons and holes within a single asymmetric Si/TiO2 nanowire. Kelvin probe force microscopy measurements show

  16. Splitting methods for split feasibility problems with application to Dantzig selectors

    Science.gov (United States)

    He, Hongjin; Xu, Hong-Kun

    2017-05-01

    The split feasibility problem (SFP), which refers to the task of finding a point that belongs to a given nonempty, closed and convex set, and whose image under a bounded linear operator belongs to another given nonempty, closed and convex set, has promising applicability in modeling a wide range of inverse problems. Motivated by the increasingly data-driven regularization in the areas of signal/image processing and statistical learning, in this paper, we study the regularized split feasibility problem (RSFP), which provides a unified model for treating many real-world problems. By exploiting the split nature of the RSFP, we shall gainfully employ several efficient splitting methods to solve the model under consideration. A remarkable advantage of our methods lies in their easier subproblems in the sense that the resulting subproblems have closed-form representations or can be efficiently solved up to a high precision. As an interesting application, we apply the proposed algorithms for finding Dantzig selectors, in addition to demonstrating the effectiveness of the splitting methods through some computational results on synthetic and real medical data sets.

  17. Flow Cytometric Bead Sandwich Assay Based on a Split Aptamer.

    Science.gov (United States)

    Shen, Luyao; Bing, Tao; Liu, Xiangjun; Wang, Junyan; Wang, Linlin; Zhang, Nan; Shangguan, Dihua

    2018-01-24

    A few aptamers still bind their targets after being split into two moieties. Split aptamers have shown great potential in the development of aptameric sensors. However, only a few split aptamers have been generated because of lack of knowledge on the binding structure of their parent aptamers. Here, we report the design of a new split aptamer and a flow cytometric bead sandwich assay using a split aptamer instead of double antibodies. Through DMS footprinting and mutation assay, we figured out the target-binding moiety and the structure-stabilizing moiety of the l-selectin aptamer, Sgc-3b. By separating the duplex strand in the structure-stabilizing moiety, we obtained a split aptamer that bound l-selectin. After optimization of one part of the split sequence to eliminate the nonspecific binding of the split sequence pair, we developed a split-aptamer-based cytometric bead assay (SACBA) for the detection of soluble l-selectin. SACBA showed good sensitivity and selectivity to l-selectin and was successfully applied for the detection of spiked l-selectin in the human serum. The strategies for generating split aptamers and designing the split-aptamer-based sandwich assay are simple and efficient and show good practicability in aptamer engineering.

  18. SplitRFLab: A MATLAB GUI toolbox for receiver function analysis based on SplitLab

    Science.gov (United States)

    Xu, Mijian; Huang, Hui; Huang, Zhouchuan; Wang, Liangshu

    2016-02-01

    We add new modules for receiver function (RF) analysis in SplitLab toolbox, which includes the manual RF analysis module, automatic RF analysis and related quality control modules, and H- k stacking module. The updated toolbox (named SplitRFLab toolbox), especially its automatic RF analysis module, could calculate the RFs quickly and efficiently, which is very useful in RF analysis with huge amount of seismic data. China is now conducting the ChinArray project that plans to deploy thousands of portable stations across Chinese mainland. Our SplitRFLab toolbox may obtain reliable RF results quickly at the first time, which provide essentially new constraint to the crustal and mantle structures.

  19. The pyrimidine nucleotide carrier PNC1 and mitochondrial trafficking of thymidine phosphates in cultured human cells

    International Nuclear Information System (INIS)

    Franzolin, Elisa; Miazzi, Cristina; Frangini, Miriam; Palumbo, Elisa; Rampazzo, Chiara; Bianchi, Vera

    2012-01-01

    In cycling cells cytosolic de novo synthesis of deoxynucleotides is the main source of precursors for mitochondrial (mt) DNA synthesis. The transfer of deoxynucleotides across the inner mt membrane requires protein carriers. PNC1, a SLC25 family member, exchanges pyrimidine nucleoside triphosphates in liposomes and its downregulation decreases mtUTP concentration in cultured cells. By an isotope-flow protocol we confirmed transport of uridine nucleotides by PNC1 in intact cultured cells and investigated PNC1 involvement in the mt trafficking of thymidine phosphates. Key features of our approach were the manipulation of PNC1 expression by RNA interference or inducible overexpression, the employment of cells proficient or deficient for cytosolic thymidine kinase (TK1) to distinguish the direction of flow of thymidine nucleotides across the mt membrane during short pulses with [ 3 H]-thymidine, the determination of mtdTTP specific radioactivity to quantitate the rate of mtdTTP export to the cytoplasm. Downregulation of PNC1 in TK1 − cells increased labeled dTTP in mitochondria due to a reduced rate of export. Overexpression of PNC1 in TK1 + cells increased mtdTTP pool size and radioactivity, suggesting an involvement in the import of thymidine phosphates. Thus PNC1 is a component of the network regulating the mtdTTP pool in human cells. -- Highlights: ► Thymidine phosphates exchange between mitochondria and cytosol in mammalian cells. ► siRNA-downregulation of PNC1 delays mitochondrial dTTP export in TK1 − cells. ► PNC1 overexpression accumulates dTTP in mitochondria of TK1 + cells. ► PNC1 exchanges thymidine nucleotides across the mitochondrial inner membrane. ► PNC1 participates in the regulation of the mtdTTP pool supporting mtDNA synthesis.

  20. Structure, stability, and thermodynamics of a short intermolecular purine-purine-pyrimidine triple helix

    International Nuclear Information System (INIS)

    Pilch, D.S.; Shafer, R.H.; Levenson, C.

    1991-01-01

    The authors have investigated the structure and physical chemistry of the d(C 3 T 4 C 3 )·2[d(G 3 A 4 G 3 )] triple helix by polyacrylamide gel electrophoresis (PAGE), 1 H NMR, and ultraviolet (UV) absorption spectroscopy. The triplex was stabilized with MgCl 2 at neutral pH. PAGE studies verify the stoichiometry of the strands comprising the triplex and indicate that the orientation of the third strand in purine-purine-pyrimidine (pur-pur-pyr) triplexes is antiparallel with respect to the purine strand of the underlying duplex. Imino proton NMR spectra provide evidence for the existence of new purine-purine (pur·pur) hydrogen bonds, in addition to those of the Watson-Crick (W-C) base pairs, in the triplex structure. These new hydrogen bonds are likely to correspond to the interaction between third-strand guanine NH1 imino protons and the N7 atoms of guanine residues on the puring strand of the underlying duplex. Thermal denaturation of the triplex proceeds to single strands in one step, under the conditions used in this study. Binding of the third strand appears to enhance the thermal stability of the duplex by 1-3 C, depending on the DNA concentration. This marked enhancement in stability, coupled with the lack of an acidic pH requirement, suggests that pur-pur-pyr triplexes are appealing choices for use in applications involving oligonucleotide targeting of duplex DNA in vitro and in vivo

  1. Resonance effects in elastic cross sections for electron scattering on pyrimidine: Experiment and theory.

    Science.gov (United States)

    Regeta, Khrystyna; Allan, Michael; Winstead, Carl; McKoy, Vincent; Mašín, Zdeněk; Gorfinkiel, Jimena D

    2016-01-14

    We measured differential cross sections for elastic (rotationally integrated) electron scattering on pyrimidine, both as a function of angle up to 180(∘) at electron energies of 1, 5, 10, and 20 eV and as a function of electron energy in the range 0.1-14 eV. The experimental results are compared to the results of the fixed-nuclei Schwinger variational and R-matrix theoretical methods, which reproduce satisfactorily the magnitudes and shapes of the experimental cross sections. The emphasis of the present work is on recording detailed excitation functions revealing resonances in the excitation process. Resonant structures are observed at 0.2, 0.7, and 4.35 eV and calculations for different symmetries confirm their assignment as the X̃(2)A2, Ã(2)B1, and B̃(2)B1 shape resonances. As a consequence of superposition of coherent resonant amplitudes with background scattering the B̃(2)B1 shape resonance appears as a peak, a dip, or a step function in the cross sections recorded as a function of energy at different scattering angles and this effect is satisfactorily reproduced by theory. The dip and peak contributions at different scattering angles partially compensate, making the resonance nearly invisible in the integral cross section. Vibrationally integrated cross sections were also measured at 1, 5, 10 and 20 eV and the question of whether the fixed-nuclei cross sections should be compared to vibrationally elastic or vibrationally integrated cross section is discussed.

  2. Spectroscopic analysis on the binding interaction of biologically active pyrimidine derivative with bovine serum albumin

    Directory of Open Access Journals (Sweden)

    Vishwas D. Suryawanshi

    2016-02-01

    Full Text Available A biologically active antibacterial reagent, 2–amino-6-hydroxy–4–(4-N, N-dimethylaminophenyl-pyrimidine-5-carbonitrile (AHDMAPPC, was synthesized. It was employed to investigate the binding interaction with the bovine serum albumin (BSA in detail using different spectroscopic methods. It exhibited antibacterial activity against Escherichia coli and Staphylococcus aureus which are common food poisoning bacteria. The experimental results showed that the fluorescence quenching of model carrier protein BSA by AHDMAPPC was due to static quenching. The site binding constants and number of binding sites (n≈1 were determined at three different temperatures based on fluorescence quenching results. The thermodynamic parameters, enthalpy change (ΔH, free energy (ΔG and entropy change (ΔS for the reaction were calculated to be 15.15 kJ/mol, –36.11 kJ/mol and 51.26 J/mol K according to van't Hoff equation, respectively. The results indicated that the reaction was an endothermic and spontaneous process, and hydrophobic interactions played a major role in the binding between drug and BSA. The distance between donor and acceptor is 2.79 nm according to Förster's theory. The alterations of the BSA secondary structure in the presence of AHDMAPPC were confirmed by UV–visible, synchronous fluorescence, circular dichroism (CD and three-dimensional fluorescence spectra. All these results indicated that AHDMAPPC can bind to BSA and be effectively transported and eliminated in the body. It can be a useful guideline for further drug design.

  3. In Situ Structural Characterization of Ferric Iron Dimers in Aqueous Solutions

    DEFF Research Database (Denmark)

    Zhu, Mengqiang; Puls, Brendan W.; Frandsen, Cathrine

    2013-01-01

    destructively with that from paths belonging to Fe(OH2)63+ monomers that coexist with the dimers, leading to a less apparent Fe shell in the EXAFS Fourier transform. This might be a reason why the characteristic Fe–Fe distance was not detected in previous EXAFS studies. The existence of μ-oxo dimers is further...... confirmed by Mössbauer analyses of analogous quick frozen solutions. This work also explores the electronic structure and the relative stability of the μ-oxo dimer in a comparison to the dihydroxo dimer using density function theory (DFT) calculations. The identification of such dimers in aqueous solutions...

  4. Poly(alizarin red)/Graphene modified glassy carbon electrode for simultaneous determination of purine and pyrimidine

    Energy Technology Data Exchange (ETDEWEB)

    Ba Xi; Luo Liqiang [Department of Chemistry, Shanghai University, Shanghai 200444 (China); Ding Yaping, E-mail: wdingyp@sina.com [Department of Chemistry, Shanghai University, Shanghai 200444 (China); Zhang Zhen [Department of Chemistry, Shanghai University, Shanghai 200444 (China); Chu Yuliang [Instrumental Analysis and Research Center, Shanghai University, Shanghai 200444 (China); Wang Bijun; Ouyang Xiaoqian [Department of Chemistry, Shanghai University, Shanghai 200444 (China)

    2012-11-08

    Graphical abstract: DPVs of PAR/Graphene/GCE (a) and the bare GCE (c) in 0.1 M PBS containing 50.0 {mu}M G, 50.0 {mu}M A, 100.0 {mu}M T and 100.0 {mu}M C, (b) PAR/Graphene/GCE in 0.1 M PBS. Highlights: Black-Right-Pointing-Pointer The sensor exhibited well-separated peaks and low detection limit. Black-Right-Pointing-Pointer The sensor possesses high sensitivity and wide linear range. Black-Right-Pointing-Pointer The sensor was used for simultaneous detection of G, A, T and C successfully. Black-Right-Pointing-Pointer The sensor was applied in a fish sperm DNA sample with satisfactory results. Black-Right-Pointing-Pointer The proposed sensor has good stability and reproducibility. - Abstract: In this work, a poly(alizarin red)/Graphene composite film modified glassy carbon electrode (PAR/Graphene/GCE) was prepared for simultaneous determination of four DNA bases (guanine, adenine, thymine and cytosine) without any pretreatment. The morphology and interface property of PAR/Graphene films were examined by scanning electron microscopy and electrochemical impedance spectroscopy. The PAR/Graphene/GCE exhibited excellent electrocatalytic activity toward purine (guanine and adenine) and pyrimidine (thymine and cytosine) in 0.1 M phosphate buffer solution (pH 7.4). Under optimum conditions, differential pulse voltammetry was used to detect the oxidation of purine and pyrimidine. The results showed that PAR/Graphene/GCE exhibited well-separated peaks, low detection limit, high sensitivity and wide linear range for simultaneous detection of purine and pyrimidine. The proposed sensor also has good stability and reproducibility. Furthermore, the modified electrode was applied for the detection of DNA bases in a fish sperm DNA sample with satisfactory results.

  5. 2, 4-Diamino-6- hydroxy pyrimidine inhibits NSAIDs induced nitrosyl-complex EPR signals and ulcer in rat jejunum

    Directory of Open Access Journals (Sweden)

    Bjarnason I

    2002-04-01

    Full Text Available Abstract Background It has been suggested that one aspect of non-steroidal anti-inflammatory drugs induced intestinal damage is due to either uncoupling of mitochondrial oxidative phosphorylation or inhibition of electron transport. We investigated the latter possibility using electron paramagnetic resonance spectroscopy. Results Electron paramagnetic studies of NSAIDS on sub-mitochondrial particles revealed that indomethacin, but not with nabumetone, bound to a site near to Complex I and ubiquinone to generate a radical species. Normal rats exhibited prominent [3Fe-4S]ox signals (g ~ 2.01 at 20 K. One hour after indomethacin there was a prominent, intense and broad absorption pattern at (g ~2.07 suggesting, appearance of radical species overlapping [3Fe-4S]ox and was unaffected by pretreatment with 2,4 diamino -6-hydroxy pyrimidine. At 24 hrs, when macroscopic ulcers were seen, there was a new signal due to a nitric oxide radical (NO•. In contrast, nabumetone and 2,4 diamino-6-hydroxy pyrimidine pre-treated animals receiving indomethacin exhibited electron paramagnetic resonance spectra identical to those of controls at 24 hrs and neither was associated with small intestinal ulcers. Indomethacin and 2,4 diamino hydroxy pyrimidine pre-treated rats, but not nabumetone, had increased intestinal permeability. Conclusion The results suggest that the in vivo effects of indomethacin modulate the mitochondrial respiratory chain directly at 1 h and 24 h through formation of nitric oxide. NO• appears to play an important role in the late pathogenic stages of NSAID enteropathy and may be the site for targeted treatment to reduce their toxicity.

  6. Infrared study of some 2-substituted-6-hydroxy-4-pyrimidine carboxylic acids. Correlation with MO-calculations

    Directory of Open Access Journals (Sweden)

    IVAN O. JURANIC

    2000-06-01

    Full Text Available The IR spectra of a series of 2-substituted-6-hydroxy-4-pyrimidine carboxylic acids (substituent = OH, SH, CH3, CH3S and NH2 were studied from the aspect of the influence of the subsitutent on the polarizability of some bonds, keto-enol tautomerism and hydrogen bond formation. The spectra were taken using solids due to the low solubility of the acids. Theoretical calculations were done using the MNDO-AM1 semiempirical molecular-orbital method. The stabilities of various tautomers were calculated simulating the dielectric continuum using the COSMO facility of the MOPAC program package. Theoretical calculations were made for all the possible tautomers of the 2-substituted-6-hydroxy-4-pyrimidine carboxylic acids. For the most stable isomers, the vibrational spectra were calculated. For the majority of the compounds the most stable isomer was identified having the structure 2-Y-6-oxo-4-carboxy-3H-pyrimidine. Besides this structure, for the 2-amino-, and 2-methyl- derivatives the zwitterionic forms have very similar stability. The 2-hydroxy compound is most stable as the 2,6-dioxo-1H, 3H isomer. The calculated vibrations for the compounds with a single stable structure correlate very well with the experimental frequencies. For the 2-methyl- and 2-amino- compounds the correlation is considerably less satisfactory. The most probable reason for this deviation is the existence of two or more tautomets in equilibrium. The correlation of the measured frequencies and the pKa values of the acids, indicate that the same tautomers exist in the solid state and in the solution.

  7. Poly(alizarin red)/Graphene modified glassy carbon electrode for simultaneous determination of purine and pyrimidine

    International Nuclear Information System (INIS)

    Ba Xi; Luo Liqiang; Ding Yaping; Zhang Zhen; Chu Yuliang; Wang Bijun; Ouyang Xiaoqian

    2012-01-01

    Graphical abstract: DPVs of PAR/Graphene/GCE (a) and the bare GCE (c) in 0.1 M PBS containing 50.0 μM G, 50.0 μM A, 100.0 μM T and 100.0 μM C, (b) PAR/Graphene/GCE in 0.1 M PBS. Highlights: ► The sensor exhibited well-separated peaks and low detection limit. ► The sensor possesses high sensitivity and wide linear range. ► The sensor was used for simultaneous detection of G, A, T and C successfully. ► The sensor was applied in a fish sperm DNA sample with satisfactory results. ► The proposed sensor has good stability and reproducibility. - Abstract: In this work, a poly(alizarin red)/Graphene composite film modified glassy carbon electrode (PAR/Graphene/GCE) was prepared for simultaneous determination of four DNA bases (guanine, adenine, thymine and cytosine) without any pretreatment. The morphology and interface property of PAR/Graphene films were examined by scanning electron microscopy and electrochemical impedance spectroscopy. The PAR/Graphene/GCE exhibited excellent electrocatalytic activity toward purine (guanine and adenine) and pyrimidine (thymine and cytosine) in 0.1 M phosphate buffer solution (pH 7.4). Under optimum conditions, differential pulse voltammetry was used to detect the oxidation of purine and pyrimidine. The results showed that PAR/Graphene/GCE exhibited well-separated peaks, low detection limit, high sensitivity and wide linear range for simultaneous detection of purine and pyrimidine. The proposed sensor also has good stability and reproducibility. Furthermore, the modified electrode was applied for the detection of DNA bases in a fish sperm DNA sample with satisfactory results.

  8. Effects of Dimers on Cooperation in the Spatial Prisoner's Dilemma Game

    International Nuclear Information System (INIS)

    Li Haihong; Cheng Hongyan; Dai Qionglin; Ju Ping; Yang Junzhong; Zhang Mei

    2011-01-01

    We investigate the evolutionary prisoner's dilemma game in structured populations by introducing dimers, which are defined as that two players in each dimer always hold a same strategy. We find that influences of dimers on cooperation depend on the type of dimers and the population structure. For those dimers in which players interact with each other, the cooperation level increases with the number of dimers though the cooperation improvement level depends on the type of network structures. On the other hand, the dimers, in which there are not mutual interactions, will not do any good to the cooperation level in a single community, but interestingly, will improve the cooperation level in a population with two communities. We explore the relationship between dimers and self-interactions and find that the effects of dimers are similar to that of self-interactions. Also, we find that the dimers, which are established over two communities in a multi-community network, act as one type of interaction through which information between communities is communicated by the requirement that two players in a dimer hold a same strategy. (general)

  9. An unusual correlation between ppGpp pool size and rate of ribosome synthesis during partial pyrimidine starvation of Escherichia coli

    DEFF Research Database (Denmark)

    Vogel, Ulla; Pedersen, Steen; Jensen, Kaj Frank

    1991-01-01

    Escherichia coli was exposed to partial pyrimidine starvation by feeding a pyrBI strain orotate as the only pyrimidine source. Subsequently, differential rates of synthesis of rRNA and of a few ribosome-associated proteins as well as the pool sizes of nucleoside triphosphates and ppGpp were...... measured. As theorotate concentration in the medium was reduced, the growth rate decreased and the pools of pyrimidine nucleotides, particularly UTP, declined. We did not observe the normal inverse relation between concentration of ppGpp and growth rate; rather, we observed that the ppGpp pool was low...

  10. Method of orthogonally splitting imaging pose measurement

    Science.gov (United States)

    Zhao, Na; Sun, Changku; Wang, Peng; Yang, Qian; Liu, Xintong

    2018-01-01

    In order to meet the aviation's and machinery manufacturing's pose measurement need of high precision, fast speed and wide measurement range, and to resolve the contradiction between measurement range and resolution of vision sensor, this paper proposes an orthogonally splitting imaging pose measurement method. This paper designs and realizes an orthogonally splitting imaging vision sensor and establishes a pose measurement system. The vision sensor consists of one imaging lens, a beam splitter prism, cylindrical lenses and dual linear CCD. Dual linear CCD respectively acquire one dimensional image coordinate data of the target point, and two data can restore the two dimensional image coordinates of the target point. According to the characteristics of imaging system, this paper establishes the nonlinear distortion model to correct distortion. Based on cross ratio invariability, polynomial equation is established and solved by the least square fitting method. After completing distortion correction, this paper establishes the measurement mathematical model of vision sensor, and determines intrinsic parameters to calibrate. An array of feature points for calibration is built by placing a planar target in any different positions for a few times. An terative optimization method is presented to solve the parameters of model. The experimental results show that the field angle is 52 °, the focus distance is 27.40 mm, image resolution is 5185×5117 pixels, displacement measurement error is less than 0.1mm, and rotation angle measurement error is less than 0.15°. The method of orthogonally splitting imaging pose measurement can satisfy the pose measurement requirement of high precision, fast speed and wide measurement range.

  11. Association of atoms into universal dimers using an oscillating magnetic field.

    Science.gov (United States)

    Langmack, Christian; Smith, D Hudson; Braaten, Eric

    2015-03-13

    In a system of ultracold atoms near a Feshbach resonance, pairs of atoms can be associated into universal dimers by an oscillating magnetic field with a frequency near that determined by the dimer binding energy. We present a simple expression for the transition rate that takes into account many-body effects through a transition matrix element of the contact. In a thermal gas, the width of the peak in the transition rate as a function of the frequency is determined by the temperature. In a dilute Bose-Einstein condensate of atoms, the width is determined by the inelastic scattering rates of a dimer with zero-energy atoms. Near an atom-dimer resonance, there is a dramatic increase in the width from inelastic atom-dimer scattering and from atom-atom-dimer recombination. The recombination contribution provides a signature for universal tetramers that are Efimov states consisting of two atoms and a dimer.

  12. Multicomponent click synthesis of new 1,2,3-triazole derivatives of pyrimidine nucleobases: promising acidic corrosion inhibitors for steel.

    Science.gov (United States)

    González-Olvera, Rodrigo; Espinoza-Vázquez, Araceli; Negrón-Silva, Guillermo E; Palomar-Pardavé, Manuel E; Romero-Romo, Mario A; Santillan, Rosa

    2013-12-06

    A series of new mono-1,2,3-triazole derivatives of pyrimidine nucleobases were synthesized by one-pot copper(I)-catalyzed 1,3-dipolar cycloaddition reactions between N-1-propargyluracil and thymine, sodium azide and several benzyl halides. The desired heterocyclic compounds were obtained in good yields and characterized by NMR, IR, and high resolution mass spectrometry. These compounds were investigated as corrosion inhibitors for steel in 1 M HCl solution, using electrochemical impedance spectroscopy (EIS) technique. The results indicate that these heterocyclic compounds are promising acidic corrosion inhibitors for steel.

  13. Consortium analysis of gene and gene–folate interactions in purine and pyrimidine metabolism pathways with ovarian carcinoma risk

    DEFF Research Database (Denmark)

    Kelemen, Linda E; Terry, Kathryn L; Goodman, Marc T

    2014-01-01

    SCOPE: We reevaluated previously reported associations between variants in pathways of one-carbon (1-C) (folate) transfer genes and ovarian carcinoma (OC) risk, and in related pathways of purine and pyrimidine metabolism, and assessed interactions with folate intake. METHODS AND RESULTS: Odds...... was previously reported to be associated with OC, may influence risk; however, stratification by folate intake is unlikely to modify disease risk appreciably in these women. SHMT1 SNP-by-folate interactions are plausible but require further validation. Polymorphisms in selected genes in purine metabolism were...

  14. Injuries caused by firewood splitting machines.

    Science.gov (United States)

    Hellstrand, P H

    1989-01-01

    The aim of this paper is to present the types of injury caused by firewood splitting machines and also to elucidate the accident mechanism. The study is based on 15 cases. The machine has a rotating spiral cone, and usually the victims' gloved fingertips were caught by the point of the cone. This led to either amputations, usually of radial fingers and/or penetrating wounds through the middle of the hand. In most cases the accidents could not be blamed on bad working techniques. The study of the mechanisms of injury points to insufficient protective devices in a machine construction which has a potentially dangerous working principle.

  15. Emergence of a Dimer-Dimer Interaction in the Low-Energy Effective Quantum-Dimer Model of a Diamond-Like-Decorated Square-Lattice Heisenberg Antiferromagnets with Further Neighbor Couplings

    Science.gov (United States)

    Hirose, Yuhei; Oguchi, Akihide; Fukumoto, Yoshiyuki

    2017-12-01

    We study spin-1/2 Heisenberg antiferromagnets on a diamond-like-decorated square lattice perturbed by two kinds of further neighbor couplings. In our previous study [https://doi.org/10.7566/JPSJ.85.094002" xlink:type="simple">J. Phys. Soc. Jpn. 85, 094002 (2016)], the second-order effective Hamiltonian for the Heisenberg model perturbed by a further neighbor coupling was found to be a square-lattice quantum-dimer model with a finite hopping amplitude, t > 0, and no dimer-dimer interaction, v = 0. In this study, we introduce another kind of further neighbor coupling and show that it leads to an attractive interaction between dimers, which suggests the stabilization of the columnar phase of the square-lattice quantum-dimer model. The calculated v/t is presented as a function of the ratio of the two exchange parameters in the Heisenberg model.

  16. Solution structure of the dimeric cytoplasmic domain of syndecan-4

    DEFF Research Database (Denmark)

    Shin, J; Lee, W; Lee, D

    2001-01-01

    cytoplasmic domain is dependent on its oligomeric status, the conformation of the syndecan-4 cytoplasmic domain itself is important in the understanding of its biological roles. Gel filtration results show that the syndecan-4 cytoplasmic domain (4L) itself forms a dimer stabilized by ionic interactions......The syndecans, transmembrane proteoglycans which are involved in the organization of cytoskeleton and/or actin microfilaments, have important roles as cell surface receptors during cell-cell and/or cell-matrix interactions. Since previous studies indicate that the function of the syndecan-4...... in the center of the dimeric twist similar to our previously reported 4V structure. The overall topology of the central variable region within the 4L structure is very similar to that of 4V complexed with the phosphatidylinositol 4,5-bisphosphate; however, the intersubunit interaction mode is affected...

  17. Dimers on two types of lattices on the Klein bottle

    Science.gov (United States)

    Lu, Fuliang; Zhang, Lianzhu

    2012-12-01

    The problem of enumerating close-packed dimers, or perfect matchings, on two types of lattices (the so-called 8.8.4 and 8.8.6 lattices) embedded on the Klein bottle is considered, and we obtain the explicit expression of the number of close-packed dimers and entropy. Our results imply that 8.8.4 lattices have the same entropy under three different boundary conditions (cylindrical, toroidal and Klein bottle) and 8.8.6 lattices have the same property. This article is part of ‘Lattice models and integrability’, a special issue of Journal of Physics A: Mathematical and Theoretical in honour of F Y Wu's 80th birthday.

  18. Stability of gold atoms and dimers adsorbed on graphene

    International Nuclear Information System (INIS)

    Varns, R; Strange, P

    2008-01-01

    We report density functional theory (DFT) calculations for gold atoms and dimers on the surface of graphene. The calculations were performed using the plane wave pseudopotential method. Calculations were performed for a variety of geometries, and both the graphene surface and gold atoms were allowed to fully relax. In agreement with experiment, our results show that the gold-gold interaction is considerably stronger than the gold-graphene interaction, implying that uniform coverage could not be attained. The minimum energy configuration for a single gold atom is found to be directly above a carbon atom, while for the dimer it is perpendicular to the surface and directly above a carbon-carbon bond. Our results are consistent with previous similar calculations

  19. Oxidative catalytic dimerization of methane: Syngas process alternative

    International Nuclear Information System (INIS)

    Salvi, G.

    1991-01-01

    A review of research progress relative to the direct conversion of methane into liquid hydrocarbons through oxidative catalytic dimerization indicates that high carbon (C 2 ) yields can be obtained in experimental conditions in which there is a high linear gas velocity, i.e., velocities greater than 0.45 m/s, at temperatures ranging between 800 and 850 degrees C, and with volumetric methane/oxygen ratios of 2 to 10. The high linear velocities have the function of preventing back-mixing phenomena and consequent product degradation. The suitable integration of dimerization (exothermic) with cracking (endothermic) of ethane to ethylene and higher olefins, as well as, oligomerization of the olefins to liquid hydrocarbons (synthesis fuels) can allow for the development of an very interesting process from both technical and economic points of view, especially for those countries with a mix of abundant natural gas reserves and scarce petroleum resources

  20. A new phenylspirodrimane dimer from the fungus Stachybotrys chartarum.

    Science.gov (United States)

    Ding, Zhang-Gui; Ding, Jian-Hai; Zhao, Jiang-Yuan; Chunyu, Wei-Xun; Li, Ming-Gang; Gu, Shao-Jie; Wang, Fei; Wen, Meng-Liang

    2018-03-01

    A new phenylspirodrimane dimer, named stachartarin A (1), was isolated from cultures of the tin mine tailings-associated fungus Stachybotrys chartarum. Its structures were elucidated by means of spectroscopic methods. At the same time, the compound was tested for its cytotoxicity against HL-60, SMMC-7721, A-549, MCF-7, and SW480 cells. Copyright © 2018 Elsevier B.V. All rights reserved.

  1. A new dimeric anthraquinone from endophytic Talaromyces sp. YE3016.

    Science.gov (United States)

    Xie, Xiao-Song; Fang, Xiao-Wei; Huang, Rong; Zhang, Shou-Peng; Wei, Hong-Xia; Wu, Shao-Hua

    2016-08-01

    A new unsymmetrical dimeric anthraquinone, 3-demethyl-3-(2-hydroxypropyl)-skyrin (1) was isolated from the solid-state fermentation extract of an endophytic fungal strain Talaromyces sp. YE 3016, together with five known compounds, skyrin (2), oxyskyrin (3), emodin (4), 1,3,6-trihydroxy-8-methyl-anthraquinone (5) and ergosterol (6). The structure of the new compound was elucidated on the basis of spectroscopic analysis. Compounds 1-3 exhibited moderate cytotoxic activities against MCF-7 cell line.

  2. Plasmonic dimer antennas for surface enhanced Raman scattering.

    Science.gov (United States)

    Höflich, Katja; Becker, Michael; Leuchs, Gerd; Christiansen, Silke

    2012-05-11

    Electron beam induced deposition (EBID) has recently been developed into a method to directly write optically active three-dimensional nanostructures. For this purpose a metal-organic precursor gas (here dimethyl-gold(III)-acetylacetonate) is introduced into the vacuum chamber of a scanning electron microscope where it is cracked by the focused electron beam. Upon cracking the aforementioned precursor gas, 3D deposits are realized, consisting of gold nanocrystals embedded in a carbonaceous matrix. The carbon content in the deposits hinders direct plasmonic applications. However, it is possible to activate the deposited nanostructures for plasmonics by coating the EBID structures with a continuous silver layer of a few nanometers thickness. Within this silver layer collective motions of the free electron gas can be excited. In this way, EBID structures with their intriguing precision at the nanoscale have been arranged in arrays of free-standing dimer antenna structures with nanometer sized gaps between the antennas that face each other with an angle of 90°. These dimer antenna ensembles can constitute a reproducibly manufacturable substrate for exploiting the surface enhanced Raman effect (SERS). The achieved SERS enhancement factors are of the order of 10⁴ for the incident laser light polarized along the dimer axes. To prove the signal enhancement in a Raman experiment we used the dye methyl violet as a robust test molecule. In future applications the thickness of such a silver layer on the dimer antennas can easily be varied for tuning the plasmonic resonances of the SERS substrate to match the resonance structure of the analytes to be detected.

  3. Synthesis and anti-inflammatory activity of phenylbutenoid dimer analogs

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Sung Soo; Fang, Yuan Ying; Park, Hae Eil [Kangwon National University, Chuncheon (Korea, Republic of)

    2015-06-15

    Several phenylbutenoid dimer (PBD) analogs were synthesized and evaluated for their inhibitory activities against nitric oxide (NO) production and TNF-α release. The PBD analogs were synthesized via Diels–Alder and subsequent Schlosser reactions as key steps. Among the tested compounds, two analogs (8c, 8f) exhibited much stronger inhibitory activity against LPS-stimulated NO production and TNF-α release in RAW 264.7 cells than that of wogonin.

  4. Antimicrobial Oligophenalenone Dimers from the Soil Fungus Talaromyces stipitatus

    OpenAIRE

    Zang , Yi; Genta-Jouve , Grégory; Escargueil , Alexandre E.; Larsen , Annette K.; Guedon , Laura; Nay , Bastien; Prado , Soizic

    2016-01-01

    International audience; New polyketide-derived oligophenalenone dimers, 9a-epi-bacillisporin E (1) and bacillisporins F–H (2–5), along with the known bacillisporin A (6), were isolated from the fungus Talaromyces stipitatus. Their structures and absolute configurations were determined on the basis of spectroscopic analyses, electronic circular dichroism, and GIAO NMR shift calculation followed by DP4 analysis. The antimicrobial activity of these compounds was evaluated against a panel of huma...

  5. Dimerization effect of sucrose octasulfate on rat FGF1

    International Nuclear Information System (INIS)

    Kulahin, N.; Kiselyov, V.; Kochoyan, A.; Kristensen, O.; Kastrup, Jette S.; Berezin, V.; Bock, E.; Gajhede, M.

    2008-01-01

    The work describes the sucrose octasulfate-mediated dimerization of rat FGF1 by gel-filtration experiments and crystal structure determination. Fibroblast growth factors (FGFs) constitute a family of at least 23 structurally related heparin-binding proteins that are involved in regulation of cell growth, survival, differentiation and migration. Sucrose octasulfate (SOS), a chemical analogue of heparin, has been demonstrated to activate FGF signalling pathways. The structure of rat FGF1 crystallized in the presence of SOS has been determined at 2.2 Å resolution. SOS-mediated dimerization of FGF1 was observed, which was further supported by gel-filtration experiments. The major contributors to the sulfate-binding sites in rat FGF1 are Lys113, Lys118, Arg122 and Lys128. An arginine at position 116 is a consensus residue in mammalian FGF molecules; however, it is a serine in rat FGF1. This difference may be important for SOS-mediated FGF1 dimerization in rat

  6. On the photophysics and photochemistry of the water dimer

    Energy Technology Data Exchange (ETDEWEB)

    Segarra-Marti, Javier; Merchan, Manuela [Instituto de Ciencia Molecular, Universitat de Valencia, P.O. Box 22085, 46071 Valencia (Spain); Roca-Sanjuan, Daniel; Lindh, Roland [Department of Chemistry - Angstroem, Theoretical Chemistry Program, Uppsala University, Box 518, 75120 Uppsala (Sweden)

    2012-12-28

    The photochemistry of the water dimer irradiated by UV light is studied by means of the complete active space perturbation theory//complete active space self-consistent field (CASPT2//CASSCF) method and accurate computational approaches like as minimum energy paths. Both electronic structure computations and ab initio molecular dynamics simulations are carried out. The results obtained show small shifts relative to a single water molecule on the vertical excitation energies of the dimer due to the hydrogen bond placed between the water donor (W{sub D}) and the water acceptor (W{sub A}). A red-shift and a blue-shift are predicted for the W{sub D} and W{sub A}, respectively, supporting previous theoretical and experimental results. The photoinduced chemistry of the water dimer is described as a process occurring between two single water molecules in which the effect of the hydrogen bond plays a minor role. Thus, the photoinduced decay routes correspond to two photodissociation processes, one for each water molecule. The proposed mechanism for the decay channels of the lowest-lying excited states of the system is established as the photochemical production of a hydrogen-bonded H{sub 2}O Horizontal-Ellipsis HO species plus a hydrogen H atom.

  7. Cooperative Formation of Icosahedral Proline Clusters from Dimers

    Science.gov (United States)

    Jacobs, Alexander D.; Jovan Jose, K. V.; Horness, Rachel; Raghavachari, Krishnan; Thielges, Megan C.; Clemmer, David E.

    2018-01-01

    Ion mobility spectrometry-mass spectrometry and Fourier transform infrared spectroscopy (FTIR) techniques were combined with quantum chemical calculations to examine the origin of icosahedral clusters of the amino acid proline. When enantiopure proline solutions are electrosprayed (using nanospray) from 100 mM ammonium acetate, only three peaks are observed in the mass spectrum across a concentration range of five orders of magnitude: a monomer [Pro+H]+ species, favored from 0.001 to 0.01 mM proline concentrations; a dimer [2Pro+H]+ species, the most abundant species for proline concentrations above 0.01 mM; and, the dimer and dodecamer [12Pro+2H]2+ for 1.0 mM and more concentrated proline solutions. Electrospraying racemic D/ L-proline solutions from 100 mM ammonium acetate leads to a monomer at low proline concentrations (0.001 to 0.1 mM), and a dimer at higher concentrations (>0.09 mM), as well as a very small population of 8 to 15 Pro clusters that comprise species from 2Pro. [Figure not available: see fulltext.

  8. Correlative SEM SERS for quantitative analysis of dimer nanoparticles.

    Science.gov (United States)

    Timmermans, F J; Lenferink, A T M; van Wolferen, H A G M; Otto, C

    2016-11-14

    A Raman microscope integrated with a scanning electron microscope was used to investigate plasmonic structures by correlative SEM-SERS analysis. The integrated Raman-SEM microscope combines high-resolution electron microscopy information with SERS signal enhancement from selected nanostructures with adsorbed Raman reporter molecules. Correlative analysis is performed for dimers of two gold nanospheres. Dimers were selected on the basis of SEM images from multi aggregate samples. The effect of the orientation of the dimer with respect to the polarization state of the laser light and the effect of the particle gap size on the Raman signal intensity is observed. Additionally, calculations are performed to simulate the electric near field enhancement. These simulations are based on the morphologies observed by electron microscopy. In this way the experiments are compared with the enhancement factor calculated with near field simulations and are subsequently used to quantify the SERS enhancement factor. Large differences between experimentally observed and calculated enhancement factors are regularly detected, a phenomenon caused by nanoscale differences between the real and 'simplified' simulated structures. Quantitative SERS experiments reveal the structure induced enhancement factor, ranging from ∼200 to ∼20 000, averaged over the full nanostructure surface. The results demonstrate correlative Raman-SEM microscopy for the quantitative analysis of plasmonic particles and structures, thus enabling a new analytical method in the field of SERS and plasmonics.

  9. Dissociative Ionization of Argon Dimer by Intense Femtosecond Laser Pulses.

    Science.gov (United States)

    Cheng, Qian; Xie, Xiguo; Yuan, Zongqiang; Zhong, Xunqi; Liu, Yunquan; Gong, Qihuang; Wu, Chengyin

    2017-05-25

    We experimentally and theoretically studied dissociative ionization of argon dimer driven by intense femtosecond laser pulses. In the experiment, we measured the ion yield and the angular distribution of fragmental ions generated from the dissociative ionization channels of (1,1) (Ar 2 2+ → Ar + + Ar + ) and (2,1) (Ar 2 3+ → Ar 2+ + Ar + ) using a cold target recoil ion momentum spectroscopy. The channel ratio of (2,1)/(1,1) is 4.5-7.5 times of the yield ratio of double ionization to single ionization of argon monomer depending on the laser intensity. The measurement verified that the ionization of Ar + is greatly enhanced if there exists a neighboring Ar + separated by a critical distance. In addition, the fragmental ions exhibit an anisotropic angular distribution with the peak along the laser polarization direction and the full width at half maximum becomes broader with increasing laser intensity. Using a full three-dimensional classical ensemble model, we calculated the angle-dependent multiple ionization probability of argon dimer in intense laser fields. The results show that the experimentally observed anisotropic angular distribution of fragmental ions can be attributed to the angle-dependent enhanced ionization of the argon dimer in intense laser fields.

  10. Randomized clinical trial comparing fixed-time split dosing and split dosing of oral Picosulfate regimen for bowel preparation.

    Science.gov (United States)

    Jun, Jae Hyuck; Han, Koon Hee; Park, Jong Kyu; Seo, Hyun Il; Kim, Young Don; Lee, Sang Jin; Jun, Baek Gyu; Hwang, Min Sik; Park, Yoon Kyoo; Kim, Myeong Jong; Cheon, Gab Jin

    2017-08-28

    To compare the efficacy of fixed-time split dose and split dose of an oral sodium picosulfate for bowel preparation. This is study was prospective, randomized controlled study performed at a single Institution (2013-058). A total of 204 subjects were assigned to receive one of two sodium picosulfate regimens ( i.e ., fixed-time split or split) prior to colonoscopy. Main outcome measurements were bowel preparation quality and subject tolerability. There was no statistical difference between the fixed-time split dose regimen group and the split dose regimen group (Ottawa score mean 2.57 ± 1.91 vs 2.80 ± 2.51, P = 0.457). Cecal intubation time and physician's satisfaction of inspection were not significantly different between the two groups ( P = 0.428, P = 0.489). On subgroup analysis, for afternoon procedures, the fixed-time split dose regimen was equally effective as compared with the split dose regimen (Ottawa score mean 2.56 ± 1.78 vs 2.59 ± 2.27, P = 0.932). There was no difference in tolerability or compliance between the two groups. Nausea was 21.2% in the fixed-time split dose group and 14.3% in the split dose group ( P = 0.136). Vomiting was 7.1% and 2.9% ( P = 0.164), abdominal discomfort 7.1% and 4.8% ( P = 0.484), dizziness 1% and 4.8% ( P = 0.113), cold sweating 1% and 0% ( P = 0.302) and palpitation 0% and 1% ( P = 0.330), respectively. Sleep disturbance was two (2%) patients in the fixed-time split dose group and zero (0%) patient in the split dose preparation ( P = 0.143) group. A fixed-time split dose regimen with sodium picosulfate is not inferior to a split dose regimen for bowel preparation and equally effective for afternoon colonoscopy.

  11. An efficient synthesis of novel pyrano[2,3-d]- and furopyrano[2,3-d]pyrimidines via indium-catalyzed multi-component domino reaction

    Directory of Open Access Journals (Sweden)

    Gohain Mukut

    2006-06-01

    Full Text Available Abstract Various novel pyrano [2,3-d]pyrimidines 5 and furopyrano [2,3-d]pyrimidines 7 were synthesized in 80–99% yields via a multicomponent domino Knoevenagel/hetero-Diels-Alder reaction of 1,3-dimethyl barbituric acid with an aromatic aldehyde and ethyl vinyl ether/2,3-dihydrofuran in presence of 1 mol% of indium(III chloride. The reaction also proceeds in aqueous media without using any catalyst, but the yield is comparatively less (65–70%.

  12. Apparent involvement of purines in the control of expression of Salmonella typhimurium pyr genes: analysis of a leaky guaB mutant resistant to pyrimidine analogs

    DEFF Research Database (Denmark)

    Jensen, Kaj Frank

    1979-01-01

    A leaky guaB mutant of Salmonella typhimurium LT-2 was obtained during a selection for mutants resistant to a combination of the two pyrimidine analogs, 5-fluorouracil and 5-fluorouridine. In the absence of exogenous guanine compounds, the growth rate of this mutant is limited by the endogenous s......%, respectively. The pyrimidine metabolism of the guaB mutant is restored completely by addition of guanine (or xanthine) to the growth medium. The data indicate purine nucleotide involvement in the regulation of expression of the pyr genes of S. typhimurium....

  13. The Regularity of Functions on Dual Split Quaternions in Clifford Analysis

    Directory of Open Access Journals (Sweden)

    Ji Eun Kim

    2014-01-01

    Full Text Available This paper shows some properties of dual split quaternion numbers and expressions of power series in dual split quaternions and provides differential operators in dual split quaternions and a dual split regular function on Ω⊂ℂ2×ℂ2 that has a dual split Cauchy-Riemann system in dual split quaternions.

  14. Splitting of the weak hypercharge quantum

    International Nuclear Information System (INIS)

    Nielsen, H.B.; Brene, N.

    1990-12-01

    The ratio between the weak hypercharge quantum for particles having no coupling to the gauge bosons corresponding to the semisimple component of the gauge group and the smallest hypercharge quantum for particles that do have such couplings is exceptionally large for the standard model, considering its rank. To compare groups with respect to this property we propose a quantity χ which depends on the rank of the group and the splitting ratio of the hypercharge(s) to be found in the group. The quantity χ has maximal value for the gauge group of the standard model. This suggest that the hypercharge splitting may play an important role either in the origin of the gauge symmetry at a fundamental scale or in some kind of selection mechanism at a scale perhaps nearer to the experimental scale. Such selection mechanism might be what we have called confusion which removes groups with many (so called generalized) automorphisms. The quantity χ tends to be large for groups with few generalized automorphisms. (orig.)

  15. Strong CP, flavor, and twisted split fermions

    International Nuclear Information System (INIS)

    Harnik, Roni; Perez, Gilad; Schwartz, Matthew D.; Shirman, Yuri

    2005-01-01

    We present a natural solution to the strong CP problem in the context of split fermions. By assuming CP is spontaneously broken in the bulk, a weak CKM phase is created in the standard model due to a twisting in flavor space of the bulk fermion wavefunctions. But the strong CP phase remains zero, being essentially protected by parity in the bulk and CP on the branes. As always in models of spontaneous CP breaking, radiative corrections to theta bar from the standard model are tiny, but even higher dimension operators are not that dangerous. The twisting phenomenon was recently shown to be generic, and not to interfere with the way that split fermions naturally weaves small numbers into the standard model. It follows that out approach to strong CP is compatible with flavor, and we sketch a comprehensive model. We also look at deconstructed version of this setup which provides a viable 4D model of spontaneous CP breaking which is not in the Nelson-Barr class. (author)

  16. An Iterative Algorithm for the Split Equality and Multiple-Sets Split Equality Problem

    Directory of Open Access Journals (Sweden)

    Luoyi Shi

    2014-01-01

    Full Text Available The multiple-sets split equality problem (MSSEP requires finding a point x∈∩i=1NCi, y∈∩j=1MQj such that Ax=By, where N and M are positive integers, {C1,C2,…,CN} and {Q1,Q2,…,QM} are closed convex subsets of Hilbert spaces H1, H2, respectively, and A:H1→H3, B:H2→H3 are two bounded linear operators. When N=M=1, the MSSEP is called the split equality problem (SEP. If  B=I, then the MSSEP and SEP reduce to the well-known multiple-sets split feasibility problem (MSSFP and split feasibility problem (SFP, respectively. One of the purposes of this paper is to introduce an iterative algorithm to solve the SEP and MSSEP in the framework of infinite-dimensional Hilbert spaces under some more mild conditions for the iterative coefficient.

  17. Theoretical investigation on the 2e/12c bond and second hyperpolarizability of azaphenalenyl radical dimers: Strength and effect of dimerization

    Science.gov (United States)

    Zhong, Rong-Lin; Xu, Hong-Liang; Sun, Shi-Ling; Qiu, Yong-Qing; Zhao, Liang; Su, Zhong-Min

    2013-09-01

    An increasing number of chemists have focused on the investigations of two-electron/multicenter bond (2e/mc) that was first introduced to describe the structure of radical dimers. In this work, the dimerization of two isoelectronic radicals, triazaphenalenyl (TAP) and hexaazaphenalenyl (HAP) has been investigated in theory. Results show TAP2 is a stable dimer with stronger 2e/12c bond and larger interaction energy, while HAP2 is a less stable dimer with larger diradical character. Interestingly, the ultraviolet-visible absorption spectra suggest that the dimerization induces a longer wavelength absorption in visible area, which is dependent on the strength of dimerization. Significantly, the amplitude of second hyperpolarizability (γyyyy) of HAP2 is 1.36 × 106 a.u. that is larger than 7.79 × 104 a.u. of TAP2 because of the larger diradical character of HAP2. Therefore, the results indicate that the strength of radical dimerization can be effectively detected by comparing the magnitude of third order non-linear optical response, which is beneficial for further theoretical and experimental studies on the properties of complexes formed by radical dimerization.

  18. Qualitative point-of-care D-dimer testing compared with quantitative D-dimer testing in excluding pulmonary embolism in primary care

    NARCIS (Netherlands)

    Lucassen, W. A. M.; Erkens, P. M. G.; Geersing, G. J.; Büller, H. R.; Moons, K. G. M.; Stoffers, H. E. J. H.; van Weert, H. C. P. M.

    2015-01-01

    General practitioners can safely exclude pulmonary embolism (PE) by using the Wells PE rule combined with D-dimer testing. To compare the accuracy of a strategy using the Wells rule combined with either a qualitative point-of-care (POC) D-dimer test performed in primary care or a quantitative

  19. Neutral dipole-dipole dimers: A new field in science

    Science.gov (United States)

    Kosower, Edward M.; Borz, Galina

    2018-03-01

    Dimer formation with dipole neutralization produces species such as low polarity water (LPW) compatible with hydrophobic surfaces (Phys. Chem. Chem. Phys. 2015, 17, 24895-24900) Dimerization and dipole neutralization occurs for N-methylacetamide on polyethylene, a behavior drastically different from its contortions in acetonitrile on AgBr:AgCl planar crystals (AgX) (ChemPhysChem 2014, 15, 3598-3607). The weak infrared absorption of the amide dimer on polyethylene is shown experimentally. Dimerization of palmitic acid is shown along with some of the many ramifications for intracellular systems. Polyoligomers of water are present on polyethylene surfaces. Some high resolution spectra of three of the polyoligomers of water are shown along with a mechanistic scheme for polyoligomer formation and dissolution. The structures of some of the oligomers are known from spectroscopic studies of water on AgX. The scope of the article begins with PE, generally accepted as hydrophobic. The IR of PE revealed not only that water was present but that it appeared in two forms, oligomers (O) and polyoligomers (PO). How did we recognize what they were? These species had been observed as especially strong "marker" peaks in the spectra1 of water placed on planar AgX, a platform developed by Katzir and his coworkers [6]. But there was a problem: the proximity to PE of oligomers with substantial (calculated) dipole moments and thus polarity, including cyclic hexamers of water (chair and boat forms), the cyclic pentamer, the books I and II, and the cyclic trimer [7a]. Another link was needed, a role perfectly fit by the already cited low polarity water (LPW). The choice was experimentally supported by the detection of low intensity absorption in the bending region.Some important generalities flow from these results. What other dimers might be present in the biological or chemical world? Palmitic acid dimer (PAD) would be a candidate for decreasing the polarity of the acid (PA). Another

  20. Aquachlorido(2-{[6-(dimethylaminopyrimidin-4-yl]sulfanyl}pyrimidine-4,6-diaminecopper(II chloride hydrate

    Directory of Open Access Journals (Sweden)

    Tristen E. Moyaert

    2017-10-01

    Full Text Available A copper(II complex of the non-symmetric bidentate ligand 2-{[6-(dimethylaminopyrimidin-4-yl]sulfanyl}pyrimidine-4,6-diamine (L1 is reported. The single-crystal X-ray structure of aqua[aqua/chlorido(0.49/0.51](2-{[6-(dimethylaminopyrimidin-4-yl]sulfanyl}pyrimidine-4,6-diaminecopper(II 0.49-chloride 1.51-hydrate, [CuCl1.51(C10H13N7S(H2O1.49]Cl0.49·1.51H2O or [(L1Cl1.51(H2O1.49Cu]0.49Cl·1.51H2O, exhibits distorted square-pyramidal geometry around the metal centre, with disorder in the axial position, occupied by chloride or water. The six-membered metal–chelate ring is in a boat conformation, and short intermolecular S...S interactions are observed. In addition to its capacity for bidentate metal coordination, the ligand has the ability to engage in further supramolecular interactions as both a hydrogen-bond donor and acceptor, and multiple interactions with lattice solvent water molecules are present in the reported structure.