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At least 19 recordsLinked to original sources
PubMed1992

High-performance liquid chromatography determination of polydeoxyribonucleotides in plasma: its application to the determination of defibrotide's pharmacokinetics in the rabbit.

We describe an HPLC method for the determination of whole polydeoxyribonucleotides in animal plasma. This method was compared to a colorimetric method, which evaluates the sugar moiety of polydeoxyribonucleotides, and to an agarose gel electrophoresis method, which evaluates the whole polydeoxyribonucleotides as does the HPLC method, and was found to give results very close to those obtained with these two other methods. A pharmacokinetic study of the antithrombotic, profibrinolytic, polydeoxyribonucleotidic drug defibrotide was carried out by evaluating the plasma drug levels by these three methods. The pharmacokinetic parameters calculated from the data are very similar.

Animals↗
PubMed1979

Cromatin and core particles formed from the inner histones and synthetic polydeoxyribonucleotides of defined sequence.

Chicken erythrocyte inner histones (H2A, H2B, H3 and H4) were associated with the two complementary homopolymeric polydeoxyribonucleotides and the two alternating copolymeric polydeoxyribonucleotides. No evidence for formation of chromatin-like structures was obtained for the complexes with poly(dG) . poly(dC) or poly(dA) . poly(dT). Both poly (dGdC) . poly(dGdC) and poly(dAdT) . poly(dAdT) could be folded by histones to yield material digested by DNAase I to multiples of about 10 and by staphylococcal nuclease to 146 bp core particles. Due to the lack of sequence heterogeniety in the complex of histones with poly(dAdT) . poly(dAdT), core particles with remarkable fine structural detail are obtained. The internal organization of DNA in the AT-containing and GC-containing core particles appears not to be identical.

Animals↗
PubMed1977

Interaction of cis- and trans-dichlorodiammine-platinum(II) with synthetic polydeoxyribonucleotides: effect of equilibrium buoyant densities.

Equilibrium buoyant densities in CS2SO4 of four synthetic double-stranded polydeoxyribonucleotides were compared following reaction with either cis-Pt(NH3)2Cl2, trans-Pt(NH3)2Cl2 or PtCl4. While both Pt(NH3)2Cl2 isomers caused significant increases in the buoyant densities (rho) of the two G + C polymers, the cis- isomer increased the rho of poly [d(G-C)] and the trans- isomer increased the rho of poly(dG) - poly(dC) more sharply than the corresponding isomer at low molar ratios of metal ion to polymer. Chloroplatinic acid was without effect. Only cis-Pt(NH3)2Cl2 produced substantial increases in the rho of poly[d(A-T)] and poly(dA) - poly(dT) with increasing metal ion concentrations. These increases were accompanied by a proportional decrease in the thermal transition temperature (Tm) of poly(dA)-poly(dT) and a sharp increase in the Tm of poly[d(A-T)]. Our results indicate that the cis- isomer reacts with all four polymers to produce rho changes clearly distinct from those values observed after reaction with either the trans- isomer or PtCl4. These results help explain the observation by others that the cis- isomer produces greater rho changes in native DNA than the trans- isomer. On the basis of our data and the published results of others, one may rationalize the quantitative differences between the cis- and trans-compounds of the buoyant densities of naturally occurring DNA; however, additional studies are clearly needed.

Binding Sites↗
PubMedDate not supplied

[Reaction of fluorescent labeled analogs of the antibiotic distamycin A with synthetic polydeoxyribonucleotides].

Interaction of DNA with the analogs of the antibiotic distamycin A having different numbers of pyrrolcarboxamide units and labeled with dansyl was studied. The intensity of fluorescence of these analogs increases markedly when they bind to DNA. It is shown that the introduction of dansyl into the analog molecules does not change their binding characteristics. The binding isotherms of the analogs to synthetic polydeoxyribonucleotides were obtained. Analysis of the experimental data leads to the following conclusions: 1. The free energy of binding of the analogs to poly(dA1 . poly(dT) depends linearly on the number of pyrrolcarboxamide units in the molecule of the analog whereas attachment of each pyrrolcarboxamide unit produces change of 2 kcal/mole in the free energy. 2. Attachment of a pyrrolcarboxamide unit to GC pair results in the free energy change of 0.95 kcal/mole. 3. Adenine and thymine are close but not equivalent by the energy of binding to the analogs of distamycin A. 4. The binding of analogs to poly(dA . poly(dT) is a cooperative process, presumably dependent on the conformational changes induced by the binding of analogs to DNA.

Chemical Phenomena↗
PubMed1976

Effect of mercuric and silver ions on cesium sulfate equilibrium buoyant densities of synthetic polydeoxyribonucleotides.

The effect of Hg2+ and Ag+ on the buoyant density (rho) of four synthetic DNA polymers, poly[d(A-T)]; poly(dA) - poly(dT); oikt[d(G-C)]; and poly(dG) - poly(dC), was investigated. The buoyant density of poly[d(A-T)] in Cs2SO4 increased dramatically after complexing with Hg2+, but little change in the buoyant density of other polymers resulted except at very high molar ratios of Hg2+/DNA-P (rf). Hg2+ raised the thermal transition temperature (Tm) of alternating polymers and lowered the Tm of homopolymers. Measurements in the preparative ultracentrifuge indicated that lowered Tm correlated with Hg2+-induced strand separation of one homopolymer [poly(dA) - poly(dT)], but strand separation was not observed with another homopolymer [poly(dG) - poly(dC)] complexed with Hg2+. When Ag+ was mixed with the polymers, the buoyant density of poly(dG) - poly(dC) increased most markedly. A substantial increase in the buoyant density of poly[d(A-T)] and a small increase in the buoyant density of poly[d(G-C)] were also observed. The Tm changes induced by Ag+ were not related in any obvious way to buoyant density changes. These findings indicate that nucleotide sequence as well as overall base composition is of importance in understanding the buoyant density changes induced by metal ions. Although these data do not allow construction of a detailed molecular model of polymer-metal ion interactions, they may be used to explain much of the behavior of naturally occurring DNA sequences, such as heterochromatic satellite sequences and 5 S and rRNA sequences, in Hg2+/Cs2SO4 and Ag+/Cs2SO4 gradients.

Base Sequence↗
PubMed1977

DNA polymerase from mesophilic and thermophilic bacteria. III. Lack of fidelity in the replication of synthetic polydeoxyribonucleotides by DNA polymerase from Bacillus licheniformis and Bacillus stearothermophilus.

1. DNA polymerase from the mesophile Bacillus licheniformis and the thermophile Bacillus stearothermophilus has been used to study the replication of poly(dA-dT)-poly(dA-dT) and poly(dC)-poly(dG) templates at 37, 45, and 55 degrees C. 2. Incorporation of non-complementary deoxyribonucleoside triphosphates (misincorporation) occurred with both enzymes and both templates. Non-specific incorporation (de novo polynucleotide synthesis, random attachment to existing strands, and tritium exchange of nucleotides) accounted for, at most, a small fraction of the total observed misincorporation. The error rates at 37 degrees C for the complete system were as follows:: B. licheniformis: dATP, 1/61; dCTP, 1/830; dGTP, 1/360; dTTP, 1/65; B. stearothermophilus: dATP, 1/68; dCTP, 1/1430; dGTP, 1/440; dTTP, 1/67. For both organisms, the error rate for dCTP and dGTP was independent of incubation temperature; the error rate for dATP and dTTP was 5-50-fold greater than that for dCTP or dGTP and increased significantly from 37 to 55 degrees C. 3. The ratio of dATP to dTTP incorporation with the poly(dA-dT)-poly-(dA-dT) template was independent of temperature and close to unity. The ratio of dCTP to dGTP incorporation with the poly(dC)-poly(dG) template decreased from approx. 0.2 to 0.05 for the mesophile and from approx. 0.06 to 0.03 for the thermophile as the temperature increased from 37 to 55 degrees C.

Bacillus↗
PubMed1977

Adduct formation between the carcinogen N-acetoxy-2-acetylaminofluorene and synthetic polydeoxyribonucleotides.

The chemical carcinogen N-acetoxy-2-acetylaminofluorene (NA-AAF) was reacted with poly(dG-dC) - poly(dG-dC); poly dG - poly dC; poly(dA-dT) - poly (dA-dT); and poly dA - poly dT under a variety of conditions. Poly (dG-homo GC polymer and 10--20 more reactive the A + T polymers. Lowering the ionic strength increased the extent of reaction, while pH change (8.9 vs. 5.5) had only a small effect. If ionic strength was adjusted so that the two guanine-containing polymers showed equal thermal stability (as judged by Tm) then the alternating copolymer was 7 times as reactive as the homopolymer. In aggreement with previous investigators, the major product was found to be 8-(N-2-fluorenylacetamido) deoxyguanosine.

Acetoxyacetylaminofluorene↗
PubMedDate not supplied

[Thermal properties of DNA and polydeoxyribonucleotides in a wide range of ionic concentration of neutral salts and a polymer].

deltaHm, deltaT, Tm of melting of polydesoxyribonucletides polydAdT,, polyd(A--T)d(A--T), polyd(A--C)d(T--G) and DNA with different basic composition in a wide range of (10-2--4.0 M) ions (C2H5)4N+, Cs+ and Na+ were determined by the method microcalorimetry. It was established that the difference in melting heats of deltaHpolydAdT--deltaHpolyd(A--T)d(A--T) being approximately 0.6 kcal/mol b. p. represents that part of the energy which is caused by the heterogeneity of Stacking of interaction between (formula: see text) pairs. It is shown that the narrowing of deltaTm with increasing DNA concentration is connected with the decrease of the difference of polyGC and poly AT melting temperatures, what is with the parameter TGC--TAT which characterizes the melting of a free macromolecule.

Animals↗
PubMed1976

Template activity of synthetic deoxyribonucleotide polymers in the eukaryotic DNA-dependent RNA polymerase reaction.

Template specificities of the eukaryotic DNA-dependent RNA polymerases A and B from rat liver, pea, and cauliflower have been investigated using synthetic polydeoxyribonucleotides. Polymerases A and B from the three species exhibit different specificities for single-stranded homopolymers: polymerase A preferentially reads poly(dT) and poly (dC). and polymerase B poly (dC). This preferential reading appears to be a property of eukaryotic DNA-dependent RNA polymerases. Polymerases A and B transcribe synthetic polyribonucleotides also, but at a reduced rate. The polyribonucleotides which can be read by DNA-dependent RNA polymerases have a base sequence similar to that of the polydeoxyribonucleotides, which are effeciently transcribed, suggesting that the base sequence of the template rather than its conformation is crucial in the template specificity for synthetic polymers. Competition experiments with polydeoxyribonucleotides indicate that the enzymes have different binding specificities, which are not the same as their template specificities.

Animals↗
PubMedDate not supplied

[The inhibition by the tumor necrosis factor of the death and DNA fragmentation of lymphoid cells in irradiated rats].

The influence of a tumor necrosis factor, administered 16 h before irradiation of rats, on the radiation response of thymus and bone marrow cells has been investigated. Three and 6 h after irradiation the following indices were analyzed: the number of apoptotic cells in the thymus; the accumulation of polydeoxyribonucleotides and the appearance of single-strand breaks in DNA of bone marrow and thymus cells; and the electrophoretic properties of thymocyte DNA. The injection of a tumor necrosis factor reduced the number of polydeoxyribonucleotides, inhibited internucleosome DNA fragmentation, and did not influence the formation of single-strand breaks in DNA.

Animals↗
PubMedDate not supplied

[Effect of space flight conditions on deoxyribonucleoprotein and nucleic acid concentrations in rat tissues].

The spleen of rats flown for 19.5 days aboard the biosatellite Cosmos-782 showed a significant increase of polydeoxyribonucleotides and a decrease of DNP and DNA. The spleen of synchronous rats did not exhibit any differences. This suggests that the increase of polydeoxyribonucleotides in flight rats immediately post-recovery was a result of the so-called gravity stress. The liver and white blood cells did not display any significant changes in DNP or nucleic acids. The changes in the content of nucleic acids in the thymus and bone marrow were insignificant.

Animals↗
PubMed1979

Methods for limiting the action of SP3 DNAase and for the determination of the direction of hydrolysis of processive exonucleases.

The action of the exonuclease SP3 DNAase is inhibited by chemical modification of DNA with the cation N-cyclohexyl-N'-beta-(4-methylmorpholinium)-ethylcarbodiimide (CME). The limited activity of the enzyme on CMA-modified DNA makes it possible to demonstrate that the enzyme also initiates its attack on polydeoxyribonucleotides at the 5'-termini. This was determined by the analysis of the products from the digestion of CME-modified DNA containing labeled 5'-terminal phosphate groups. Such procedure can be adopted as a general approach for the determination of the direction of hydrolysis of other processive exonucleases. SP3 DNAase has been shown able to degrade oligo- and polydeoxyribonucleotides with or without 5'-terminal phosphate groups with equal efficiency (Aposhian, H.V., Friedman, N., Nichihara M., Heimer, E.P., and Nussbaum, A.L. (1970) J. Mol. Biol. 49, 367-379). The present work also shows that the enzyme can even hydrolyze oligo- and polynucleotides containing derivatized phosphate groups.

Bacillus subtilis↗
PubMed1992

Effect of oral defibrotide on tissue-plasminogen activator and tissue-plasminogen activator inhibitor balance.

Defibrotide, a polydeoxyribonucleotide of mammalian origin, has been shown to reduce the blood level of the plasminogen activator inhibitor, and so to increase the activity of tissue plasminogen activator without any adverse effect. A randomized, double-blind, placebo-controlled study has been done in 22 patients, 14 with peripheral vascular disease, 6 with coronary heart disease and 2 with cerebrovascular disease. Patients were given defibrotide 400 mg b.d. or identical placebo for 30 days and the parameters of fibrinolysis were evaluated before and after the treatment. A significant increase in tissue plasminogen activator activity at rest and after venostasis was observed after defibrotide; tissue plasminogen activator antigen at rest and after venostasis was not affected by either treatment. Defibrotide significantly reduced plasminogen activator inhibitor activity and antigen at rest. Only one patient complained of gastric pain after placebo treatment. The study shows that defibrotide has profibrinolytic property and that it could be used to explore the role of plasminogen activator inhibitor in venous and arterial thrombosis.

Administration, Oral↗
PubMed1978

Electrostatic complexes of mitomycin C with nucleic acids and polyanions.

Reductively activated mitomycin C exhibits strong, non-covalent electrostatic binding to polyanions such as polyvinylsulfate and polyphosphate. The protonated C-2 amino group generated by the reduction is most likely responsible for this type of interaction. At moderate drug and salt concentrations only covalent binding to nucleic acids is observable. This is shown to be guanine-specific in DNA for the first time, as well as in synthetic polyribo- and polydeoxyribonucleotides at 10--20 times higher binding levels than previously tested. At higher mitomycin C concentration, however, strong non-covalent electrostatic binding to nucleic acids also occurs, resulting in a binding ratio up to 1 mol drug bound per mol mononucleotide, although this non-specific binding is relatively inhibited compared to polyvinylsulfate. Salts also have an inhibitory effect on the non-specific binding to nucleic acids. A series of mitomycin derivatives were compared for their binding and cross-linking abilities using DNA as substrate, with the following results: (a) the presence of a basic nitrogen . funtion at C-2 promotes binding, both covalent and electrostatic, presumably by kinetically facilitating the approach between positively charged nitrogen and DNA. (b) The aziridine ring is the major covalent binding site, indispensable for crosslinking and determines the guanine-specificity of the binding.

Anions↗