Search results for " nucleotides"

PURINE AND PYRIMIDINE NUCLEOTIDES IN THE BRAIN OF NORMAL AND CONVULSANT RATS

1969

— Purine and pyrimidine nucleotides were measured in the brain of normal and electroshocked rats after chromatographic separation on ion-exchange resin of mono-, di- and tri-phosphorylated derivatives. CMP, IMP and NAD did not show any significant quantitative change. Adenine nucleotides showed an abrupt change followed by a rapid return to the control value. GTP was the only purine nucleotide exhibiting a relatively slow return to its starting concentration. The greatest percentage increase after electroshock was observed in UMP, which returned to its control value only after 5 min; UDPCoenzymes (i.e. UDPA plus UDPG) showed a relatively small drop during the development of the seizure and …

Endogenous nitric oxide is responsible for the early loss of P450 in cultured rat hepatocytes

1998

AbstractLoss of P450 during the early hours of monolayer formation is known to be the more serious limitation of primary cultured hepatocytes as an adequate model for the study of drug metabolism, toxicity and P450 induction. This study reports that endogenous nitric oxide (NO) formation is activated shortly after isolation by the classical collagenase-based liver perfusion methods. Both rapid P450 loss and aerobic mitochondrial energy metabolism impairment – with subsequent changes on glucose metabolism – are directly related to the high local generation of the radical at this stage. These effects can be reverted by the sole addition of NO biosynthesis inhibitors during liver perfusion and…

Exercise and recovery in frog muscle: metabolism of PCr, adenine nucleotides, and related compounds

1996

The effects of exercise (swimming), fatigue, and recovery on the intracellular pH (pHi), energy-rich phosphates, and related metabolites were studied in the gastrocnemius muscle of common frogs (Rana temporaria) at 20 degrees C. Exercise caused a rapid decrease in the content of phosphocreatine (PCr) and a corresponding increase in that of Pi. The ATP level remained virtually constant for 1 min; its precipitous decrease during the following minute was associated with a rise in the contents of inosine 5'-monophosphate (IMP) and NH4+, indicating a marked activation of AMP deaminase. Five minutes of swimming caused severe fatigue, which was correlated with decreases in muscle PCr (-85%), ATP …

Genome-wide Association Analysis in Humans Links Nucleotide Metabolism to Leukocyte Telomere Length

2020

Leukocyte telomere length (LTL) is a heritable biomarker of genomic aging. In this study, we perform a genome-wide meta-analysis of LTL by pooling densely genotyped and imputed association results across large-scale European-descent studies including up to 78,592 individuals. We identify 49 genomic regions at a false dicovery rate (FDR) < 0.05 threshold and prioritize genes at 31, with five highlighting nucleotide metabolism as an important regulator of LTL. We report six genome-wide significant loci in or near SENP7, MOB1B, CARMIL1, PRRC2A, TERF2, and RFWD3, and our results support recently identified PARP1, POT1, ATM, and MPHOSPH6 loci. Phenome-wide analyses in >350,000 UK Biobank p…

(2'-5')Oligoadenylate and intracellular immunity against retrovirus infection.

1992

1. 1. The double-stranded RNA-dependent 2′,5′-oligoadenylate (2–5A) synthetase/ribonuclease L (RNase L) system plays an essential role in the establishment of the antiviral state of a cell exposed to virus infection. 2. 2. Until recently, the application of 2–5A derivatives to reinforce this system seemed to be limited mainly due to the low specificity of RNase L for viral RNA. 3. 3. Two new strategies have been developed which yield a selective antiviral effect of 2–5As at least against human immunodeficiency virus-1 (HIV-1) infection: (i) an “intracellular immunization” appproach using 2-5A synthetase cDNA linked to HIV trans -acting response element (TAR) and (ii) inhibition of retrovira…

Suitability of non-glucose-carbohydrates for parenteral nutrition

1975

Postoperative parenteral nutrition can only be optimally effective if the characteristics of post-traumatic metabolism are taken into account. Two main possibilities are discussed for the carbohydrate component of parenteral nutrition during this phase: glucose with high doses of insulin or non-glucose carbohydrates (sugar substitutes) possibly in a suitable combination with glucose. The risks as well as the technical and organisational problems involved in the use of them are discussed and the authors prefer the second of the two alternatives. Possible side effects of non-glucose carbohydrates are pointed out and it is shown how these can be avoided by observing dose guidelines. So far a c…

Leflunomide, a reversible inhibitor of pyrimidine biosynthesis?

1995

Influence of the xyloadenosine analogue of 2?,5?-oligoriboadenylate on poly(A)-specific, 2?,5?-oligoriboadenylate degrading 2?,3?-exoribonuclease and…

1984

The homogeneous poly(A)-specific 2′,3′-exoribonuclease from calf thymus gland, which cleaves both 3′,5′-and 2′,5′-linked oligoriboadenylates, does not degrade (xyloA2'p)2 xyloA, the xylofuranosyladenosine analogue of the 2-5A core. This oligonucleotide, which is supposed to enter intact cells rapidly, was found to possess an increased stability and an enhanced antiherpesvirus activity compared to the natural (A2'p)2A (Eppstein, D. A., Barnett, J. W., Marsh, Y. V., Gosselin, G. and Imbach, J.-L. (1983) Nature 302, 723–724). The poly(A) anabolic enzyme, poly(A) polymerase (Mn2+-dependent), from the same source, which is initiated by (A3'p)2A and its higher oligomers, does not accept 2–5A core…

On the Use of Metal Purine Derivatives (M=Ir, Rh) for the Selective Labeling of Nucleosides and Nucleotides

2014

The reactions of neutral or cationic IrIII and RhIII derivatives of phenyl purine nucleobases with unsymmetrical alkynes produce new metallacycles in a predictable manner, which allows for the incorporation of either photoactive (anthracene or pyrene) or electroactive (ferrocene) labels in the nucleotide or nucleoside moiety. The reported methodology (metalation of the purine derivative and subsequent marker insertion) could be used for the postfunctionalization and unambiguous labeling of oligonucleotides.

Arabinose nucleoside triphosphates are no inhibitors for DNA-dependent RNA polymerases.

1976

1-Beta-D-arabinofuranosylcytosine-5' -triphosphate and 9-beta-D-arabinofuranosyladenosine-5' -triphosphate were found to have no inhibitory potency for both mammalian DNA-dependent RNA polymerase II and E. coli DNA-dependent RNA polymerase.