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Academic literature on the topic 'Purines'

Author: Grafiati

Published: 4 June 2021

Last updated: 29 July 2024

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Journal articles on the topic "Purines"

1

Balcells, J., J. A. Guada, C. Castrillo, and J. Gasa. "Urinary excretion of allantoin and allantoin precursors by sheep after different rates of purine infusion into the duodenum." Journal of Agricultural Science 116, no. 2 (April 1991): 309–17. http://dx.doi.org/10.1017/s002185960007773x.

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SUMMARYTwo experiments were carried out to determine endogenous losses and the response of urinary purine derivatives to increased duodenal inputs of purine bases. Four ewes each fitted with a re-entrant cannula at the proximal duodenum, and conventionally fed, were subjected to full replacement of duodenal digesta followed by the administration of a solution either free of purines (Expt 1) or enriched with increasing amounts of purines, to supply 0·48–21·27 mmol/animal per day (Expt 2). Basal daily urinary excretions of allantoin, uric acid, hypoxanthine and xanthine were 11·5 ± 0·94, 9·9 ± 0·67, 6·9 ± 0·46 and 1·2 ±0·16 mg/kg W0·75. Allantoin was the only purine derivative which increased in response to incremental inputs of duodenal purines. The relationship between allantoin excretion and infused purines showed a urinary recovery of 0·8 for purines infused at > 220 μmol/kg W0·76. Lower rates of infusion did not alter allantoin excretion. The results show urinary allantoin to be a useful index to estimate duodenal input of purines when animals are fed close to or above their energy maintenance requirements.

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2

ZINN, R. A., and F. N. OWENS. "A RAPID PROCEDURE FOR PURINE MEASUREMENT AND ITS USE FOR ESTIMATING NET RUMINAL PROTEIN SYNTHESIS." Canadian Journal of Animal Science 66, no. 1 (March 1, 1986): 157–66. http://dx.doi.org/10.4141/cjas86-017.

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A rapid method for separation and quantitation of purines was applied to ruminal and intestinal digesta for estimating net microbial protein synthesis in the rumen. The procedure combines standard literature methods for hydrolysis of nucleotides by perchloric acid followed by precipitation of free purines with silver nitrate to separate the purines from interfering compounds. Acid resolubilized purines were quantitated spectrophotometrically at 260 nm. Microbial protein was estimated by the ratio of purines to N of isolated bacteria. The procedure is rapid, simple, precise and not costly. Duodenal passage of microbial N estimated by this procedure for steers fed semipurified and purified diets containing no protein was highly correlated (R2 = 0.98; P < 0.01) with duodenal passage of tungstic acid precipitable N. Results indicate that purines may be useful as a marker for quantitating microbial protein. Key words: Purine, RNA, DNA, microbial protein

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3

Hasník, Zbyněk, Radek Pohl, Blanka Klepetářová, and Michal Hocek. "Synthesis of (purin-6-yl)acetates and their transformations to 6-(2-hydroxyethyl)- and 6-(carbamoylmethyl)purines." Collection of Czechoslovak Chemical Communications 74, no. 7-8 (2009): 1035–59. http://dx.doi.org/10.1135/cccc2009042.

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A novel approach to the synthesis of (purin-6-yl)acetates was developed based on Pd-catalyzed cross-coupling reactions of 6-chloropurines with a Reformatsky reagent. Their reduction with NaBH4 and treatment with MnO2 gave 6-(2-hydroxyethyl)purines, while reactions with amines in presence of NaCN afforded 6-(carbamoylmethyl)purines. Mesylation of the 6-(2-hydroxyethyl)purines followed by nucleophilic substitutions gave rise to several 6-(2-substituted ethyl)purines. This methodology was successfully applied to the synthesis of substituted purine bases and nucleosides for cytostatic and antiviral activity screening. None of the compounds exerted significant activity.

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Verbic, J., X. B. Chen, N. A. MacLeod, and E. R. Ørskov. "Excretion of purine derivatives by ruminants. Effect of microbial nucleic acid infusion on purine derivative excretion by steers." Journal of Agricultural Science 114, no. 3 (June 1990): 243–48. http://dx.doi.org/10.1017/s0021859600072610.

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SUMMARYTwo steers totally nourished by intragastric infusion of volatile fatty acids and casein were given an abomasal infusion of a microbial protein preparation (Pruteen) at eight rates with a purine input ranging from 0 to 170 mmol/day over 11 successive 5-day periods. The urinary excretion of purine derivatives relative to the purine input was measured. Negligible amounts of xanthine plus hypoxanthine were present in the urine. The relative contributions of allantoin and uric acid to the total excretion were not affected by the rate of purine infusion. Total purine derivative excretion (uric acid and allantoin) was linearly correlated with purine input. Recovery in the urine of the infused purines was 0·77. It is suggested that utilization of exogenous purines may only occur in the intestinal mucosa and that the remaining purines may be completely converted, before entering the liver, to uric acid and allantoin, which are subsequently eliminated by the renal and extrarenal routes. The differences between cattle and sheep in excretion of purine derivatives, and the implications of these differences for the use of purine excretion values in order to estimate microbial protein supply to the ruminant, are discussed.

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5

Pons, F. W., U. Neubert, and P. Müller. "Evidence for frameshift mutations in the hisH gene of Escherichia coli causing synthesis of a partially active glutamine amidotransferase." Genetics 120, no. 3 (November 1, 1988): 657–65. http://dx.doi.org/10.1093/genetics/120.3.657.

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Abstract Among eight strains carrying acridine-induced mutations in hisH, five which mapped at four different sites in the promoter-distal region of the gene showed His+ phenotypes on media containing a purine. By complementation analysis, hisH enzyme was shown to be required for growth on purines. Purine-sensitive His+ revertants of strains able to grow on purines carried second-site mutations which in one case could be shown to map in hisG. Strains able to grow on purines were able to grow on 2-thiazolyl-DL-alanine, too. We conclude that frameshift mutations in the promoter-distal part of the hisH gene of E. coli do not completely abolish the activity of the gene product.

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6

Hristov, A. N., T. A. McAllister, D. R. Ouellet, and G. A. Broderick. "Comparison of purines and nitrogen-15 as microbial flow markers in beef heifers fed barley- or corn-based diets." Canadian Journal of Animal Science 85, no. 2 (June 1, 2005): 211–22. http://dx.doi.org/10.4141/a04-054.

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The objective of this study was to estimate the contribution of microbial purine bases to duodenal purines and to purine derivatives [allantoin and uric acid (PD)] excreted in the urine. Additionally, microbial protein (MCP) flow estimated using duodenal flow of purine bases was compared to estimates using 15N as a microbial marker. Four beef heifers were fed two diets, barley silage/barley grain/soybean meal (diet B) or corn silage/corn grain/corn gluten meal (diet C), in a cross-over design study. (15NH4)2SO4 was infused in the rumen for 8 d to label ruminal microorganisms and their purine bases. Rumen contents, duodenal digesta, urine, and feces were sampled during the last 2 d of tracer infusion and for 48 h after the infusion ceased. The animals consumed more (P < 0.01) dry matter (DM), organic matter (OM), N, and neutral detergent fiber (NDF) with diet B than with diet C. Total tract digestibilities of DM, OM, and NDF were also higher (P < 0.01) with diet B. Ruminal ammonia (P < 0.01), volatile fatty acids (P < 0.05), and acetate (P < 0.01) concentrations and xylanase activity (P < 0.05) were higher with diet B compared with diet C. Flow of MCP to the duodenum was estimated from duodenal samples using purines or 15N as microbial markers, or from urinary PD excretion. The effects of diet or method of measurement on MCP flow were not significant. However, when the urinary PD method was excluded from the analysis, MCP flow was greater (by 26%; P = 0.01) when estimated using 15N vs. the purine-based method. The difference was mainly due to underestimation of the proportion of microbial N in the liquid duodenal digesta with the purine method. Feed purines contributed from 3.5 (liquid digesta phase) to 19.7% (solid digesta phase) of the total purine flow at the duodenum. 15N enrichment of urinary PD was 1.08 of the enrichment of duodenal purines, suggesting that feed purines contributed little N to urinary allantoin and uric acid in cattle. Key words: Allantoin, cattle, microbial protein synthesis, nitrogen-15, purine derivative

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Walsh, M. J., A. Sanchez-Pozo, and N. S. Leleiko. "A regulatory element is characterized by purine-mediated and cell-type-specific gene transcription." Molecular and Cellular Biology 10, no. 8 (August 1990): 4356–64. http://dx.doi.org/10.1128/mcb.10.8.4356-4364.1990.

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Purines and purine nucleotides were found to affect transcription of the hypoxanthine-guanine phosphoribosyltransferase (HPRT) gene in whole nuclei isolated from intestinal mucosa of adult rats fed a purine- and purine nucleotide-free diet. Nuclear run-on transcription assays, performed on whole nuclei from different tissues and cell types, identified an intestine-specific decrease in the overall incorporation of [alpha-32P]UTP in HPRT transcripts from intestinal epithelial cell nuclei when exogenous purines or purine nucleotides were omitted from either the diet or culture medium. Using a 990-base-pair genomic fragment that contains the 5'-flanking region from the HPRT gene, we generated plasmid constructs with deletions, transfected the DNA into various cell types, and assayed for chloramphenicol acetyltransferase (CAT) reporter activity in vitro. We determined that an element upstream from the putative transcriptional start site is necessary to maintain the regulatory response to purine and nucleotide levels in cultured intestinal epithelial cells. These results were tissue and cell type specific and suggest that in the absence of exogenous purines, the presence of specific factors influences transcriptional initiation of HPRT. This information provides evidence for a mechanism by which the intestinal epithelium, which has been reported to lack constitutive levels of de novo purine nucleotide biosynthetic activity, could maintain and regulate the salvage of purines and nucleotides necessary for its high rate of cell and protein turnover during fluctuating nutritional and physiological conditions. Furthermore, this information may provide more insight into regulation of the broad class of genes recognized by their lack of TATA and CCAAT box consensus sequences within the region proximal to the promoter.

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8

Walsh, M. J., A. Sanchez-Pozo, and N. S. Leleiko. "A regulatory element is characterized by purine-mediated and cell-type-specific gene transcription." Molecular and Cellular Biology 10, no. 8 (August 1990): 4356–64. http://dx.doi.org/10.1128/mcb.10.8.4356.

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Purines and purine nucleotides were found to affect transcription of the hypoxanthine-guanine phosphoribosyltransferase (HPRT) gene in whole nuclei isolated from intestinal mucosa of adult rats fed a purine- and purine nucleotide-free diet. Nuclear run-on transcription assays, performed on whole nuclei from different tissues and cell types, identified an intestine-specific decrease in the overall incorporation of [alpha-32P]UTP in HPRT transcripts from intestinal epithelial cell nuclei when exogenous purines or purine nucleotides were omitted from either the diet or culture medium. Using a 990-base-pair genomic fragment that contains the 5'-flanking region from the HPRT gene, we generated plasmid constructs with deletions, transfected the DNA into various cell types, and assayed for chloramphenicol acetyltransferase (CAT) reporter activity in vitro. We determined that an element upstream from the putative transcriptional start site is necessary to maintain the regulatory response to purine and nucleotide levels in cultured intestinal epithelial cells. These results were tissue and cell type specific and suggest that in the absence of exogenous purines, the presence of specific factors influences transcriptional initiation of HPRT. This information provides evidence for a mechanism by which the intestinal epithelium, which has been reported to lack constitutive levels of de novo purine nucleotide biosynthetic activity, could maintain and regulate the salvage of purines and nucleotides necessary for its high rate of cell and protein turnover during fluctuating nutritional and physiological conditions. Furthermore, this information may provide more insight into regulation of the broad class of genes recognized by their lack of TATA and CCAAT box consensus sequences within the region proximal to the promoter.

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Safranow, Krzysztof, and Zygmunt Machoy. "Methylated Purines in Urinary Stones." Clinical Chemistry 51, no. 8 (August 1, 2005): 1493–98. http://dx.doi.org/10.1373/clinchem.2005.048033.

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Abstract Background: The aim of the study was to measure the content of methylated purines that appear as admixtures in uric acid stones. Methods: We analyzed urinary calculi from 48 residents of Western Pomerania who underwent surgery at the urology ward in Szczecin. Stone samples were dissolved in 0.1 mol/L NaOH. Extracts were diluted in 50 mmol/L KH2PO4 and analyzed by reversed-phase HPLC with ultraviolet detection and use of a gradient of methanol concentration and pH. Results: Uric acid was the main component of 9 stones. All 9 showed admixtures of 9 other purine derivatives: endogenous purine breakdown products (xanthine, hypoxanthine, and 2,8-dihydroxyadenine) and exogenous methyl derivatives of uric acid and xanthine (1-, 3-, and 7-methyluric acid; 1,3-dimethyluric acid; and 3- and 7-methylxanthine). Amounts of these purine derivatives ranged from the limit of detection to 12 mg/g of stone weight and showed a strong positive correlation (Spearman rank correlation coefficients, 0.63–0.94) with the uric acid content of the samples. The main methylated purine in the stones was 1-methyluric acid. Conclusions: Urinary purines at concentrations below their saturation limits may coprecipitate in samples supersaturated with uric acid and appear as admixtures in urinary stones. The amount of each purine depends on its average urinary excretion, similarity to the chemical structure of uric acid, and concentration of the latter in the stone. These findings suggest that purines in stones represent a substitutional solid solution with uric acid as solvent. Methylxanthines, which are ubiquitous components of the diet, drugs, and uric acid calculi, may be involved in the pathogenesis of urolithiasis.

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Burres, Neal S., and Carol E. Cass. "The effects of hypoxanthine on methotrexate-induced differentiation of cultured human choriocarcinoma (BeWo) cells." Biochemistry and Cell Biology 64, no. 8 (August 1, 1986): 811–15. http://dx.doi.org/10.1139/o86-109.

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When cultured human choriocarcinoma (BeWo) cells arc exposed to methotrexate, proliferation ceases and cells undergo a complex differentiative response that resembles development of normal trophoblast. Although thymidylate starvation has been shown to be causative in methotrexate-induced expression of syncytiotrophoblastic markers by BeWo cells, the role of purine deprivation is uncertain since previous studies utilized growth media containing exogenous purines. This work investigated the effects of hypoxanthine on methotrexate-induced cell enlargement, expression of placental alkaline phosphatase, and morphological differentiation to the syncytiotrophoblast-like phenotype. When methotrexate exposures (1 μM, 48 h) were conducted in a purine-frec basal medium supplemented with dialyzed fetal bovine serum, RNA synthesis was greatly reduced and cell enlargement did not occur. Specific methods for removing purines (charcoal extraction and xanthine oxidase treatment) decreased the ability of serum to support cell enlargement during methotrexate exposures, whereas addition of hypoxanthine to culture fluids restored its ability to support maximal increases in cell mass, confirming that purines were the factors lost during dialysis. In contrast, morphological differentiation to the syncytiotrophoblast-like phenotype and increased expression of placental alkaline phosphatase were unaffected by the availability of purines during exposure to methotrexate.

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Dissertations / Theses on the topic "Purines"

1

Denis, Valérie. "Régulation des gènes de la biosynthèse des purines chez la levure Saccharomyces Cerevisiae." Bordeaux 2, 1999. http://www.theses.fr/1999BOR28660.

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2

Fairhurst, Neil. "Synthesis of modified purines." Thesis, Imperial College London, 1990. http://hdl.handle.net/10044/1/46294.

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Petrilli, Camila Lopes. "Regulação da atividade da glândula pineal por estimulação purinérgica." Universidade de São Paulo, 2012. http://www.teses.usp.br/teses/disponiveis/41/41135/tde-01052013-140517/.

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A biossíntese de MEL pela pineal envolve a conversão da serotonina a NAS pela enzima AA-NAT, seguida demetilação da NAS pela enzima HIOMT gerando a MEL. A ativação β-adrenérgica é essencial e a co-estimulação de receptores P2Y1 potencia a produção de NAS induzida por noradrenalina. Neste trabalho avaliamos o efeito da estimulação de receptores P2Y1 sobre a produção de MEL induzida pela estimulação β-adrenérgica. A co-estimulação purinérgica com ADP, levou a potenciação da produção de NAS induzida por ISO e a inibição do conteúdo de MEL de maneira dependente de concentração. Em extratos nucleares de pineais estimuladas com ADP, a translocação nuclear de AP-1 foi observada, não havendo alteração significativa na translocação nuclear dos dímeros NF-κB p50/p50 e p50/RelA. PDTC, inibidor de NF-κB, não alterou o conteúdo de NAS e MEL em pineais em cultura estimuladas com ISO e ADP. A expressão gênica e a atividade enzimática de AA-NAT e HIOMT não foram alteradas pela co-estimulação com ISO e ADP. O bloqueio seletivo dos receptores P2Y1 por A3\'P5\'P inibiu de maneira dependente de concentração o efeito potenciador do ADP sobre a produção de NAS induzida por ISO, mas não reverteu a inibição observada nos níveis de melatonina. Estes resultados apontam para um mecanismo diferencial de modulação da produção de NAS e MEL abrindo novas perspectivas ao estudo dos mecanismos regulatórios da produção de MEL e seus metabólitos
The biosynthesis of MEL by the pineal gland involves the conversion of serotonin to NAS by the enzyme AA-NAT, followed by methylation of NAS by the enzyme HIOMT generating MEL. The activation of β-adrenergic receptors is essential and the co-stimulation of P2Y1 receptors potentiates noradrenaline-induced NAS production. In this study we evaluated the effect of P2Y1 receptors stimulation on the production of MEL synthesis induced by β-adrenergic stimulation. Purinergic co-stimulation with ADP potentiated ISO-induced NAS production and inhibited melatonin content in a concentration dependent manner. In nuclear extracts from stimulated pineal glands with ADP, the nuclear translocation of AP-1 was observed, with no significant change in the nuclear translocation of the NF-κB dimers p50/p50 and p50/RelA. PDTC, an inhibitor of NF-κB, did not alter the content of NAS and MEL in cultured pineal glands co-stimulated with ISO and ADP. ISO and ADP co-stimulation did not alter the transcript and enzyme activity of AA-NAT and HIOMT. The selective blockade of P2Y1 receptors by A3\'P5\'P inhibited, in a concentration-dependent manner, the potentiating effect of ADP on ISO-induced NAS production but did not change the inhibition observed on MEL levels. These results suggest a differential mechanism on the modulation of NAS and MEL production opening new perspectives to the study of the regulatory mechanisms involved in the biosynthesis of MEL and its metabolites

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Worthington, Rebecca A. (Ann). "Structure-function studies of P2X receptors." Thesis, The University of Sydney, 2001. https://hdl.handle.net/2123/27719.

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P2X receptors are fast, ATP-gated cation ion channels. To date seven subtypes of P2X receptors have been cloned and identified, PZXH. The membrane topology of the P2X subunit consists of intracellular amino- and carboxy-termini, two transmembrane spanning domains and a large extracellular loop. Despite similar membrane topology, within this family of receptors the P2X subtypes possess different functional characteristics. They exhibit different sensitivities to agonists and antagonists, are modulated differently by extracellular ions, and have different pore forming abilities. The regions that are responsible for differences in function between P2X subtypes have not been elucidated. This thesis aims to further knowledge regarding the relationship between the structure of the P2X family and differences in the function of the various receptor subtypes. Examination of the primary structure of the P2X receptor family led to the identification of epitope regions suitable for antibody production. This suite of antibodies was tested for specificity and the distribution of P2X receptors was examined in a range of rat tissues and two cell lines. The pathophysiological involvement of the P2X7 receptor was examined in B-CLL patients. Two polymorphisms as well as a loss of function mutation were identified in both normal and leukaemic populations. The site of agonist binding is believed to be within the extracellular loop. Examination of the primary structure of the human cytolytic receptor P2X7 led to the identification of two noncontiguous regions that could potentially be involved in binding ATP. Three amino acid residues that lie within the extracellular loop were targeted and their involvement in ATP binding was determined. Two lysine residues at positions 193 and 31 1 and a proline residue at 210 were each exchanged with alanine. An abolition of function of human receptors with mutations at positions 193 or 311 was observed, consistent with a disruption of the ATP binding domain, although alterations in transduction or gating cannot be dismissed. The P2X receptor appears to be comprised of a trimeric subunit arrangement, and Hill coefficients of between 1 and 3 reported for ATP binding suggest that there is more than one ATP binding site per functional receptor. Modelling of the putative binding cleft of the hP2X7 subunit was performed and the residues important for ATP binding were highlighted. The fimctional trimeric receptor appears to possess three intersubunit ATP binding sites. In an attempt to isolate regions of the extracellular domain that contribute to or control various channel properties, chimaeras between subtypes P2X], P2X4 and P2X7 were constructed and their properties examined. Each of the six chimaeras has been shown to be correctly inserted into the cell membrane and functional. These constructs will continue to be investigated and form the basis for extensive future work.

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5

Ghérardi, Arnaud. "Toxoplasma gondii : étude de la purine nucléoside phosphorylase." Lyon 1, 2001. http://www.theses.fr/2001LYO1T208.

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La 4e de couverture indique : "Toxoplasma gondii est un protozoaire Apicomplexa responsable de toxoplasmose congénitale et cérabrale. Cette dernière est une importante cause de morbidité et de mortalité chez l'immunodéprimé. Comme la majorité des protozoaires, T. Gondii est incapable de synthétiser ses propres purines et dépend donc entièrement de celles de son hôte. Il dispose des enzymes pour interconvertir celles-ci de façon à former les bases puriques qui intégreront divers métabolimes et constitueront les acides nucléiques. Le dosage de six enzymes de la voie des purines a montré que la purine nucléoside phosphorylase (PNP Ec 2. 4. 2. 1) présentait l'activité enzymatique la plus élevée dans le cerveau murin et dans la forme tachyzoi͏̈te de la souche ME49 du parasite isolé de culture cellulaire. L'enzyme de cerveaux de souris saines et de souris parasitées par la souche avirulente DUR de T. Gondii a été purifiée d'un facteur 40. La PNP de tachyzoi͏̈tes de la souche virulente RH et avirulente ME49 isolés de culture cellulaire a été purifiée d'un facteur 11 et la détermination des paramètres cinétiques montre une différence entre l'enzyme du parasite et celle de l'hôte. Des composés chimiques inhibiteurs de la PNP de protozoaires et des composés de formules originales, synthétisés par le laboratoire de Chimie Organique, ont été testés, et l'activité enzymatique de l'enzyme a été dosée par chromatographie liquide haute performance afin de déterminer les IC50 et les Ki des inhibiteurs. La révélation histoenzymatique par précipitation du plomb a été réalisée. L'activité PNP sur des coupes de kyste cérébral de souris et sur des tachyzoi͏̈tes de la souche ME49 de T. Gondii isolés de culture cellulaire a été mise en évidence par microscopie électronique. La localisation de la PNP est cytoplasmique et est particulièrement importante dans les tachyzoi͏̈tes par rapport à leur cellules hôtes. Une intense activité intracytoplasmique péri-membranaire a été observée dans ces formes. "

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6

Kahn, Kalju. "Kinetic and mechanistic characterization of the urate oxidase reaction /." free to MU campus, to others for purchase, 1998. http://wwwlib.umi.com/cr/mo/fullcit?p9924895.

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Wong, Cecilia Sui Si. "A study of the purinergic receptors : A1R and P2Y1R in their homodimerization and receptor signaling /." View abstract or full-text, 2005. http://library.ust.hk/cgi/db/thesis.pl?BICH%202005%20WONG.

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8

Tyagi, Surendera Kumar. "Electrochemical and enzyme-catalyzed oxidation chemistry of some biologically important purine derivatives (uric acid, 9-B-D-ribofuranosyluric acid and xanthosine) /." Full-text version available from OU Domain via ProQuest Digital Dissertations, 1986.

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9

Longthorne, Darren Stuart. "Thieno-extended purines and related ring systems." Thesis, University of Salford, 1994. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.261839.

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10

Oliveira, Lisandre de. "Métodos em nutrição de ruminantes: uso de índices fecais para estimar consumo e estimativa da síntese proteica microbiana ruminal." Universidade Federal de Santa Maria, 2009. http://repositorio.ufsm.br/handle/1/10733.

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Conselho Nacional de Desenvolvimento Científico e Tecnológico
This study was carried out to evaluate methods in ruminant nutrition: use of fecal index to estimate intake and use of purine or purine derivatives to estimate rumen microbial protein synthesis. Data from three digestibility trials conducted with castrated male lambs fed ryegrass (Lolium multiflorum, Lam) or Cynodon (Cynodon dactylon var dactylon) at different levels of intake were compiled. Intake data were related to faecal excretion of different chemical compounds through regression analysis. Significant regressions with high R2 were used to calculate estimated intake values, which were compared to observed values by paired t test. Organic matter (OM) intake (g/day) had significant (P<0.01) relation to faecal excretion (g/day) of N and/or acid detergent fiber (ADF) in ryegrass trial (R2 varied from 0.69 to 0.85) while N, ADF and neutral detergent fiber (NDF) had significant (P<0.01) relation to OM intake in Cynodon trials (R2 varied from 0.51 to 0.56). It is concluded that faecal excretion of N and/or ADF had high potential to estimate intake by grazing animals. Rumen microbial protein synthesis estimated either by duodenal purines or urine purines derivatives was different (P<0.01). Moreover, these estimates were highly affected by purines:microbial N proportion used in calculations.
O objetivo deste trabalho foi avaliar métodos em nutrição de ruminantes: o uso de índices fecais para estimar consumo e uso de purinas no duodeno ou de derivados de purinas na urina para estimar a síntese de nitrogênio microbiano ruminal. Foram compilados dados de três ensaios de digestibilidade in vivo utilizando ovinos machos castrados não fistulados ou fistulados no duodeno alimentados com azevém (Lolium multiflorum, Lam) ou capim-paulista (Cynodon dactylon var dactylon) fornecidos verde a diferentes níveis de consumo. Os dados de consumo foram relacionados à excreção fecal de diferentes componentes químicos. As equações de regressão com coeficientes de correlação mais significativos foram utilizadas para calcular consumos estimados, os quais foram comparados pelo teste t para dados pareados com os consumos observados. O consumo de MO foi significativamente (P<0,01) relacionado com a excreção fecal de N e/ou fibra em detergente ácido (FDA) no ensaio com azevém (R2 variou de 0,69 a 0,85) e com a excreção fecal de N, FDA ou fibra em detergente neutro (FDN) nos ensaios com Cynodon (R2 variou de 0,51 a 0,56). Conclui-se que a excreção fecal de FDA e/ou N tem um alto potencial para estimar consumo por animais em pastejo. A síntese de nitrogênio microbiano ruminal estimado pela metodologia das purinas duodenais ou dos derivados de purinas excretados na urina não foi similar (P<0,01). Adicionalmente, estas estimativas foram altamente influenciadas pela relação purinas:N microbiano utilizada nos cálculos.

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Books on the topic "Purines"

1

Stone, T. W., ed. Purines. London: Palgrave Macmillan UK, 1985. http://dx.doi.org/10.1007/978-1-349-07564-5.

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2

Lister, John Henry. The purines. New York: Wiley, 1996.

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3

Burnstock, Geoffrey, James G. Dobson, Bruce T. Liang, and Joel Linden, eds. Cardiovascular Biology of Purines. Boston, MA: Springer US, 1998. http://dx.doi.org/10.1007/978-1-4615-5603-9.

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Abd-Elfattah, Anwar-Saad A., and Andrew S. Wechsler, eds. Purines and Myocardial Protection. Boston, MA: Springer US, 1996. http://dx.doi.org/10.1007/978-1-4613-0455-5.

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Jacobson, Kenneth A., John W. Daly, and Vincent Manganiello, eds. Purines in Cellular Signaling. New York, NY: Springer New York, 1990. http://dx.doi.org/10.1007/978-1-4612-3400-5.

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A, Abd-Elfattah Anwar-Saad, and Wechsler Andrew, eds. Purines and myocardial protection. Boston: Kluwer Academic Publishers, 1996.

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Geoffrey, Burnstock, ed. Cardiovascular biology of purines. Norwell, Mass: Kluwer Academic Publishers, 1998.

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8

Stone, T. W., and H. A. Simmonds. Purines: Basic and Clinical Aspects. Dordrecht: Springer Netherlands, 1991. http://dx.doi.org/10.1007/978-94-011-3911-3.

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W, Stone T., and IUPHAR International Congress of Pharmacology, (9th : 1984 : London), eds. Purines: Pharmacology and physiological roles. Basingstoke: Macmillan, 1985.

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W, Stone T., International Union of Pharmacology, and International Congress of Pharmacology (9th : 1984 : London, England), eds. Purines: Pharmacology and physiological roles. Weinheim, Federal Republic of Germany: VCH, 1985.

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Book chapters on the topic "Purines"

1

Broadley, Kenneth J. "Purines." In Airways Smooth Muscle: Neurotransmitters, Amines, Lipid Mediators and Signal Transduction, 271–307. Basel: Birkhäuser Basel, 1995. http://dx.doi.org/10.1007/978-3-0348-7504-2_8.

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Brown, E. G. "Purines." In Ring Nitrogen and Key Biomolecules, 128–66. Dordrecht: Springer Netherlands, 1998. http://dx.doi.org/10.1007/978-94-011-4906-8_6.

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Mehlhorn, Heinz. "Purines." In Encyclopedia of Parasitology, 1–3. Berlin, Heidelberg: Springer Berlin Heidelberg, 2015. http://dx.doi.org/10.1007/978-3-642-27769-6_2606-2.

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Mehlhorn, Heinz. "Purines." In Encyclopedia of Parasitology, 2293–95. Berlin, Heidelberg: Springer Berlin Heidelberg, 2016. http://dx.doi.org/10.1007/978-3-662-43978-4_2606.

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Stone, T. W. "Summary of a Symposium Discussion on Purine Receptor Nomenclature." In Purines, 1–4. London: Palgrave Macmillan UK, 1985. http://dx.doi.org/10.1007/978-1-349-07564-5_1.

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White, Thomas D. "Release of ATP from Central and Peripheral Nerve Terminals." In Purines, 95–105. London: Palgrave Macmillan UK, 1985. http://dx.doi.org/10.1007/978-1-349-07564-5_10.

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Barberis, C., V. Leviel, and J. L. Daval. "Metabolism and Release of Purines from Nervous Tissue." In Purines, 107–14. London: Palgrave Macmillan UK, 1985. http://dx.doi.org/10.1007/978-1-349-07564-5_11.

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Chaudry, Irshad H., Mark G. Clemens, and Arthur E. Baue. "Uptake of ATP by Tissues." In Purines, 115–24. London: Palgrave Macmillan UK, 1985. http://dx.doi.org/10.1007/978-1-349-07564-5_12.

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Berne, Robert M. "Adenosine and the Cardiovascular System: Some of the Problems and Controversies." In Purines, 125–30. London: Palgrave Macmillan UK, 1985. http://dx.doi.org/10.1007/978-1-349-07564-5_13.

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Winn, H. Richard. "Metabolic Regulation of Cerebral Blood Flow by Adenosine." In Purines, 131–41. London: Palgrave Macmillan UK, 1985. http://dx.doi.org/10.1007/978-1-349-07564-5_14.

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Conference papers on the topic "Purines"

1

Čerňa, Igor, and Michal Hocek. "Direct C–H arylation of purines and purine nucleosides." In XIVth Symposium on Chemistry of Nucleic Acid Components. Prague: Institute of Organic Chemistry and Biochemistry, Academy of Sciences of the Czech Republic, 2008. http://dx.doi.org/10.1135/css200810327.

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Zucolotto Cocca, Leandro H., André G. Pelosi, Sandrine Piguel, Cleber Renato Mendonça, and Leonardo De Boni. "Two - photon Brightness is increased in push-pull purines nucleobases." In Latin America Optics and Photonics Conference. Washington, D.C.: Optica Publishing Group, 2022. http://dx.doi.org/10.1364/laop.2022.tu4a.54.

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Nowadays, purines nucleobases have received great attention owing their capacity to be employed as fluorescent bioprobes for nucleic acid spectroscopic studies. Here we determine the fluorescence quantum yield and two-photon brightness in four purines nucleobases.

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Robins, Morris J. "Transformation chemistry with nucleic acid purines." In XIVth Symposium on Chemistry of Nucleic Acid Components. Prague: Institute of Organic Chemistry and Biochemistry, Academy of Sciences of the Czech Republic, 2008. http://dx.doi.org/10.1135/css200810028.

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Šilhár, Peter, Radek Pohl, Ivan Votruba, and Michal Hocek. "Synthesis and transformations of 6-(hydroxymethyl)purines." In XIIIth Symposium on Chemistry of Nucleic Acid Components. Prague: Institute of Organic Chemistry and Biochemistry, Academy of Sciences of the Czech Republic, 2005. http://dx.doi.org/10.1135/css200507221.

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Mondal, Sayan, Spriha Gogia, Namrata Jayanth, Mrinalini Puranik, P. M. Champion, and L. D. Ziegler. "Purines as Interrogators of Local Environment in Proteins and DNA." In XXII INTERNATIONAL CONFERENCE ON RAMAN SPECTROSCOPY. AIP, 2010. http://dx.doi.org/10.1063/1.3482546.

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Rathod, Pravinsinh I., A. T. Oza, P. Predeep, Mrinal Thakur, and M. K. Ravi Varma. "Infrared Spectroscopy of Charge Transfer Complexes of Purines and Pyrimidines." In OPTICS: PHENOMENA, MATERIALS, DEVICES, AND CHARACTERIZATION: OPTICS 2011: International Conference on Light. AIP, 2011. http://dx.doi.org/10.1063/1.3643633.

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Hořejší, Kateřina, Radek Pohl, and Antonín Holý. "Tricyclic etheno analogs of purines derived from 2-amino-6-chloropurine." In XIIIth Symposium on Chemistry of Nucleic Acid Components. Prague: Institute of Organic Chemistry and Biochemistry, Academy of Sciences of the Czech Republic, 2005. http://dx.doi.org/10.1135/css200507403.

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Šišuļins, Andrejs, Irina Novosjolova, Māris Turks, and Ērika Bizdēna. "Synthesis of new fluorescent 9-alkyl-6-amino-2-triazolyl purines." In XVIth Symposium on Chemistry of Nucleic Acid Components. Prague: Institute of Organic Chemistry and Biochemistry, Academy of Sciences of the Czech Republic, 2014. http://dx.doi.org/10.1135/css201414231.

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Khancheuski, M. А., V. N. Lesik, and E. I. Kvasyuk. "SYNTHESIS OF 8-BROMOADENOSINE AT DIFFERENT PH VALUES." In SAKHAROV READINGS 2021: ENVIRONMENTAL PROBLEMS OF THE XXI CENTURY. International Sakharov Environmental Institute of Belarusian State University, 2021. http://dx.doi.org/10.46646/sakh-2021-2-132-135.

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This article shows methods for the preparation of 8-bromoadenosine which is an important intermediate in the syntheses of analogs of purines nucleosides and nucleotides with a broad spectrum of biological activity. The influence of the pH values of the medium on the yield of 8-bromoadenosine was studied. It was showed that pH 4.3 is optimal for the preparation of 8-bromoadenosine by reaction of adenosine with a solution of bromine in water.

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Patel, Kavita A., Stephanie D. Davis, Robin Johnson, and Charles R. Esther Jr. "Exhaled Breath Condensate Purines Correlate With Lung Function In Infants And Preschoolers." In American Thoracic Society 2011 International Conference, May 13-18, 2011 • Denver Colorado. American Thoracic Society, 2011. http://dx.doi.org/10.1164/ajrccm-conference.2011.183.1_meetingabstracts.a6159.

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Reports on the topic "Purines"

1

Schwarzschild, Michael A. Protection by Purines in Toxin Models of Parkinson's Disease. Fort Belvoir, VA: Defense Technical Information Center, August 2014. http://dx.doi.org/10.21236/ada608811.

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Schwarzschild, Michael A. Protection by Purines in Toxin Models of Parkinson's Disease. Fort Belvoir, VA: Defense Technical Information Center, July 2013. http://dx.doi.org/10.21236/ada602446.

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Wallace, Susan S. Structure/Function Analysis of DNA-glycosylases That Repair Oxidized Purines and Pyrimidines and the Influence of Surrounding DNA Sequence on Their Interactions. Office of Scientific and Technical Information (OSTI), August 2005. http://dx.doi.org/10.2172/900301.

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Nair, Vasu. Rare 2-Substituted Purine Nucleosides. Fort Belvoir, VA: Defense Technical Information Center, October 1987. http://dx.doi.org/10.21236/adb119120.

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Nair, Vasu. Rare 2-Substituted Purine Nucleosides. Fort Belvoir, VA: Defense Technical Information Center, May 1989. http://dx.doi.org/10.21236/adb132700.

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Kim, Kami. Evaluation of Purine Salvage as a Chemotherapeutic Target in the Plasmodium yoelii Rodent Model. Fort Belvoir, VA: Defense Technical Information Center, March 2008. http://dx.doi.org/10.21236/ada486586.

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Kim, Kami. Evaluation of Purine Salvage as a Chemotherapeutic Target in the Plasmodium yoelli Rodent Model. Fort Belvoir, VA: Defense Technical Information Center, March 2007. http://dx.doi.org/10.21236/ada517113.

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DeMoll, E. The role of purine degradation in methane biosynthesis and energy production in Methanococcus vannielii. Office of Scientific and Technical Information (OSTI), October 1990. http://dx.doi.org/10.2172/6215366.

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DeMoll, E. The role of purine degradation in methane biosynthesis and energy production in Methanococcus vannielii. Office of Scientific and Technical Information (OSTI), October 1989. http://dx.doi.org/10.2172/7101119.

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DeMoll, E. The role of purine degradation in methane biosynthesis and energy production in Methanococcus vannielii. Progress report. Office of Scientific and Technical Information (OSTI), November 1998. http://dx.doi.org/10.2172/674902.

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