SEARCH · PubMed Health

Results for “Polydeoxyribonucleotides”

Explore indexed PubMed citations for clinical trials, systematic reviews and public health research. Read source abstracts and follow each citation to its original PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 145 records · Page 8Linked to original sources

PubMed1996

Defibrotide mediated inhibition of serotonin, endothelin-I, thromboxane, and serum induced contraction of canine femoral and pulmonary arterial rings.

Defibrotide is a polydeoxyribonucleotide derived agent with a weight average of 15 to 18 kDa. By virtue of its chemical nature, this polyelectrolyte agent exerts multiple pharmacologic actions at various plasmatic and cellular sites. In recent studies, this agent has been demonstrated to exhibit cardioprotective and vasomodulatory actions. To test the effect of defibrotide on the vascular smooth muscle contractile responses, its effects were evaluated on contractile response induced by agonists in canine femoral and pulmonary arterial smooth muscle preparation. These arterial preparations were harvested from anesthetized and anticoagulated (Heparinized 3-5 U/ml) dogs. Defibrotide was administered to dogs at 10 mg/kg, i.v. and segments of canine arteries were harvested at 30 minutes after the administration of this agent. The control and defibrotide treated canine arterial ring preparations were tested against serotonin, endothelin-I, serum and control platelet rich plasma(PRP) with arachidonic acid(AA). The contractile response of arterial rings obtained for treated groups were measured using serotonin, endothelin-I, serum and PRP/AA as agonists. The contractile action of serotonin, endothelin-I, serum and PRP/AA were inhibited by pretreatment of the animal with defibrotide. The arterial ring isolated from dogs treated with defibrotide exhibited a weaker contraction. These studies support the hypothesis that defibrotide modulates endothelial function and the response to the contractile actions of various agonists may be related to this effect.

Animals↗

PubMed1983

Reaction of apurinic/apyrimidinic sites with [14C]methoxyamine. A method for the quantitative assay of AP sites in DNA.

A simple and rapid method is described for the determination of AP (apurinic/apyrimidinic) sites in DNA. The method involves the reaction of [14C]methoxyamine with the aldehyde group present in the deoxyribose moiety after a base loss. Studies with alkylated-depurinated DNA and with uracil-containing polydeoxyribonucleotides depyrimidinated by uracil-DNA glycosylase show that methoxyamine reacts with both apurinic and apyrimidinic sites in a rapid and exhaustive way. Under standard conditions (30-min incubation with 5 mM methoxyamine at 37 degrees C, pH 7.2) untreated DNA is almost unreactive and the [14C]methoxyamine incorporation in DNA is proportional to the number of AP sites. Since the methoxyamine reaction is free from any degradative effect on DNA, AP sites may be estimated from a simple determination of the acid-insoluble radioactivity.

Alkylation↗

PubMed1987

Inactivation of de novo DNA methyltransferase activity by high concentrations of double-stranded DNA.

The activity of eukaryotic DNA methyltransferase diminishes with time when the enzyme is incubated with high concentrations (200-300 micrograms/ml) of unmethylated double-stranded Micrococcus luteus DNA. Under similar conditions, single-stranded DNA induces only a limited decrease of enzyme activity. The inactivation process is apparently due to a slowly progressive interaction of the enzyme with double-stranded DNA that is independent of the presence of S-adenosyl-L-methionine. The inhibited enzyme cannot be reactivated either by high salt dissociation of the DNA-enzyme complex or by extensive digestion of the DNA. Among synthetic polydeoxyribonucleotides both poly(dG-dC).poly(dG-dC) and poly(dA-dT).poly(dA-dT), but not poly(dI-dC).poly(dI-dC), cause inactivation of DNA methyltransferase. This inactivation process may be of interest in regulating the 'de novo' activity of the enzyme.

DNA↗

PubMed1978

Effect of tetramethylammonium ions on conformational changes of DNA in the premelting temperature range.

The reversible conformational change of DNAs and polydeoxyribonucleotides occurring before melting was followed by circular dichroism. deltatheta/deltaT, the rate of change of ellipticity theta with temperature, was used mainly as a measure of this premelting phenomenon. If sodium ions were replaced by tetramethylammonium ions deltatheta/deltaT decreased for poly (dA) poly (dT) and poly (dA.dT) poly (dT.dA), but increased for poly (dG.dC) poly (dC.dG). DNAs of different base composition showed no more premelting (deltatheta/deltaT approximately 0) even at low molarities of TMACl provided the Na/TMA ratio was very small. For all cases studied the theta values at 0 degrees C and at a given ionic strength were smaller in NaCl than in TMACl. When studying the series of ammonium ions from NH4+ to (C2H5)4N+, the deltatheta/deltaT values first decreased, going through zero with TMA+ ions, and then increased again. A tentative and qualitative explanation of our results can be given: (a) Hydration of the polymers increases in presence of TMA ions and their average stability decreases; locally, however, (AT) pairs are preferentially stabilized by TMA ions owing to a specific interaction at the level of O2 of thymine. (b) In order to explain the different behaviour of (AT) polymers and DNA, it is assumed that only the B structure is able to accommodate TMA ions in the small groove of the double stranded helix.

Chemical Phenomena↗

PubMed1996

Characterization and quantitation of the active polynucleotide fraction (PDRN) from human placenta, a tissue repair stimulating agent.

The polydeoxyribonucleotide (PDRN) fraction is an extract which forms the active component in a new formulation of the drug Placentex (a tissue repair stimulating agent), obtained from human placenta through an original proprietory extraction method. From a comparison of the UV, NMR and IR spectra of this fraction (before and after nuclease treatment) with that of a similar standard (Sigma D1501), it was shown that the active substances in the PDRN fraction mainly consist of a mixture of DNA fragments. By gel electrophoresis, the molecular weights of the DNA fragments were shown to range from 50 to 2000 base pairs. Finally, an HPLC method is described, based on an anion-exchange material capable of determining the amount of PDRN in different batches of the extract, which varied from 80 to 90%.

Chromatography, High Pressure Liquid↗

PubMed1985

Local base dynamics and local structural features in RNA and DNA duplexes.

Local base motion and local structural base information are derived with a simple motional model from site specifically spin-labeled polyribo- and polydeoxyribonucleotides. The model was developed earlier for some nucleic acids and has now been applied to analyze 22 different nucleic acid systems. We conclude that the base motion of the spin-labeled nucleotide in single-stranded RNA, DNA, or non-base-paired bases in duplexes is of the order of 1 ns and that its base mobility decreases by about a factor of 4 upon base pairing. Also, the tether motion of the probe is slower in an RNA than in a DNA duplex.

DNA↗

PubMed1980

Fluorescence relaxation of proflavin-deoxyribonucleic acid interaction. Kinetic properties of a base-specific reaction.

The kinetics of proflavin binding to Micrococcus lysodeicticus deoxyribonucleic acid (DNA [(G-C) content 72%], to Bacillus megaterium DNA [(A-T) content 70%], and to the polydeoxyribonucleotides poly[d(G-C)] and poly[d(A-T)] was studied with fluorescence temperature-jump methods. Poly[d(A-T)] binds proflavin in a two-step reaction with a preequilibrium. Poly[d(G-C)] is characterized by a bimolecular reaction. The binding of acridines to natural DNAs is shown to be characterized by different types of sites whose properties depend on the base composition. The sites have considerable enthalpic differences which result in exchange of dye molecules between them when the temperature is changed. Also, on natural DNAs A-T base pairs are associated with a rapidly equilibrating external complex which is absent or much weaker for G-C base pairs.

Acridines↗

PubMed1999

Defibrotide as salvage therapy for refractory veno-occlusive disease of the liver complicating allogeneic bone marrow transplantation.

A 30-year-old woman developed veno-occlusive disease of the liver during an allogeneic BMT for acute leukemia. Treatment with recombinant human tissue plasminogen activator and heparin resulted in an incomplete and transient response followed by progressive disease. The patient was then given defibrotide (DF), a mammalian tissue-derived polydeoxyribonucleotide developed for the treatment of a number of vascular disorders, which has thrombolytic and anti-thrombotic properties. No significant bleeding or other major toxicities were observed during treatment and she made a full recovery. At 6 months after the onset of VOD her liver function tests and color flow Doppler ultrasound scan are normal. Our experience supports the preliminary results already obtained with DF. Its efficacy should be evaluated in a prospective randomized fashion.

Adult↗

PubMed2004

Defibrotide in the treatment of children with veno-occlusive disease (VOD): a retrospective multicentre study demonstrates therapeutic efficacy upon early intervention.

Veno-occlusive disease (VOD) of the liver is a complication observed particularly in patients undergoing hematopoietic stem cell transplantation (HSCT). Defibrotide (DF) is a polydeoxyribonucleotide with aptameric activity on endothelium. We evaluated in a retrospective analysis the efficacy of DF in pediatric patients developing hepatic VOD after HSCT.A total of 45 patients between 0.2 and 20 years (median age: 8.2 years) with hepatic VOD were treated with DF: 22 patients (49%) met risk criteria for severe or progressive disease and 23 (51%) for moderately severe and mild disease. The median duration of DF treatment was 17 days. In all, 34 patients (76%) achieved complete response (CR) with a survival rate of 64% at day 100. CR rate in patients with severe disease was 50% with long-term survival of 36%. The average DF dose in the CR group was 45 mg/kg/day and in the no responder (NR) group 27 mg/kg/day. The use of additional drugs besides DF to treat VOD made no difference in the outcome compared to DF alone. The average interval from diagnosis to start of DF was 1 day in the CR and 5.5 days in NR group. In multivariate analysis, early intervention remained the only significant factor for a CR.

Adolescent↗

PubMed2003

Defibrotide reduces procoagulant activity and increases fibrinolytic properties of endothelial cells.

Defibrotide (DF), a polydeoxyribonucleotide with antithrombotic properties, has recently proven effective in patients with severe hepatic veno-occlusive disease (VOD), a life-threatening complication of high-dose chemo/radiotherapy regimens for stem cell transplantation. To understand the mechanism of its beneficial effect, we studied the impact of DF on the expression of tissue factor (TF) and fibrinolytic proteins (PAI-1 and t-PA) on endothelial cells. The in vitro response to DF of two types of human endothelial cells (ECs) of different origins, that is from macrovascular (HUVEC) and microvascular (HMEC-1 cell line) beds, was evaluated in the presence or absence of a proinflammatory stimulus (ie bacterial endotoxin, LPS). The results show that DF was able to significantly reduce the LPS-induced TF expression by HMEC-1, and less prominently by HUVEC. In addition, DF importantly influenced the fibrinolytic properties of both HMEC-1 and HUVEC. Specifically, it dose-dependently counteracted the LPS-induced increase in PAI-1 levels and decrease in t-PA activity expression. It also significantly incremented t-PA antigen in resting EC. Decreasing the procoagulant activity and increasing the fibrinolytic potential of EC favors an anticoagulant phenotype of the endothelium, which may protect from fibrin deposition and vascular occlusion.

Blood Coagulation Factors↗

PubMed1988

Enzyme-linked immunosorbent assays for Z-DNA.

Dot blot and transblot enzyme-linked immunosorbent assays (e.l.i.s.a.) are described which provide sensitive non-radioactive methods for screening Z-DNA-specific antisera and for detecting Z-DNA in polydeoxyribonucleotides and supercoiled plasmids. In the alkaline phosphatase dot blot e.l.i.s.a., Z-DNA, Br-poly(dG-dC).poly(dG-dC), or B-DNA, poly(dG-dC).poly(dG-dC), poly(dA-dT).poly(dA-dT), Br-poly(dI-dC).poly(dI-dC), or salmon sperm DNA were spotted onto nitrocellulose discs and baked. The e.l.i.s.a. was conducted in 48-well culture dishes at 37 degrees C using a rabbit polyclonal antiserum developed against Br-poly(dG-dC).poly(dG-dC), an alkaline phosphatase-conjugated second antibody, and p-nitrophenol as the substrate. Under conditions where antibody concentrations were not limiting, alkaline phosphatase activity was linear for 2 h. Dot blot e.l.i.s.a. conditions are described which allow quantification of Z-DNA [Br-poly(dG-dC).poly(dG-dC)] within the range 5-250 ng. Dot blot and transblot horseradish peroxidase e.l.i.s.a. are described that detect Z-DNA within supercoiled plasmid DNAs immobilized on diazophenylthioether (DPT) paper. In the transblot e.l.i.s.a., plasmid pUC8 derivatives containing 16, 24, or 32 residues of Z-DNA were electrophoresed in agarose gels and electrophoretically transferred to DPT paper. Z-DNA-antibody complexes were detected by the horseradish peroxidase-catalysed conversion of 4-chloro-1-naphthol to a coloured product that was covalently bound to the DPT paper. Z-DNA antibody reactivity was specific for supercoiled Z-DNA containing plasmids after removal of the antibodies cross-reactive with B-DNA by absorption onto native DNA-cellulose. The transblot e.l.i.s.a. was sensitive enough to detect 16 base pairs of alternating G-C residues in 100 ng of pUC8 DNA.

Alkaline Phosphatase↗

PubMed2000

Defibrotide for the treatment of hepatic veno-occlusive disease: results of the European compassionate-use study.

Severe hepatic veno-occlusive disease (VOD) is a recognized complication of autologous and allogeneic stem cell transplantation (SCT) that is often fatal. Defibrotide (DF) is a polydeoxyribonucleotide that has been found to have anti-thrombotic, anti-ischaemic and thrombolytic properties without causing significant anticoagulation. Preliminary studies have demonstrated activity for DF in the treatment of VOD, with minimal associated toxicity. In the present study, 40 patients who fulfilled established criteria for VOD were treated with DF on compassionate grounds in 19 European centres; 28 patients met risk criteria predicting progression of VOD and fatality or had evidence of multiorgan failure (MOF), and were defined as 'poor-risk'. DF was commenced intravenously at a median of 14 d (range, -2 d to 53 d) post SCT at doses ranging from 10 to 40 mg/kg. The median duration of therapy was 18 d (range, 2--71 d). Twenty-two patients showed a complete response (CR) (bilirubin < 34.2 micromol/l and resolution of signs/symptoms of VOD and end-organ dysfunction) [CR = 55%, confidence interval (CI) 40--70%] and 17 patients (43%) are alive beyond d +100. Ten poor-risk patients showed a complete response (CR = 36%, CI 21--51%). These results demonstrate that DF is an active treatment for VOD following SCT and a randomized trial is now underway in order to further evaluate its role.

Acute Disease↗

PubMed2002

Effects of defibrotide, a novel oligodeoxyribonucleotide, on ischaemia and reperfusion injury of the rat liver.

1. The purpose of this study was to investigate the protective effects of defibrotide, a single-stranded polydeoxyribonucleotide, on ischaemia-reperfusion injury to the liver using a rat model. 2. Ischaemia of the left and median lobes was created by total inflow occlusion for 30 min followed by 60 min of reperfusion. Hepatic injury was assessed by the release of liver enzymes (alanine transferase, ALT and lactic dehydrogenase, LDH). Hepatic oxidant stress was measured by superoxide production, lipid peroxidation and nitrite/nitrate formation. Leukocyte-endothelium interaction and Kupffer cell mobilization were quantified by measuring hepatic myeloperoxidase (MPO), polymorphonuclear leukocyte adherence to superior mesenteric artery (SMA) and immunostaining of Kupffer cell. 3. Defibrotide treatment resulted in a significant inhibition of postreperfusion superoxide generation, lipid peroxidation, serum ALT activity, serum LDH activity, MPO activity, serum nitrite/nitrate level, leukocyte adherence to SMA, and Kupffer cell mobilization, indicating a significant attenuation of hepatic dysfunction. 4. A significant correlation existed between liver ischaemia/reperfusion and hepatic injury, suggesting that liver ischaemia/reperfusion injury is mediated predominantly by generation of oxygen free radicals and mobilization of Kupffer cells. 5. We conclude that defibrotide significantly protects the liver against liver ischaemia/reperfusion injury by interfering with Kupffer cell mobilization and formation of oxygen free radicals. This study provides strong evidence that defibrotide has important beneficial effects on acute inflammatory tissue injury such as that occurring in the reperfusion of the ischaemic liver.

Animals↗

PubMed2002

Defibrotide modulates prostaglandin production in the rat mesenteric vascular bed.

Defibrotide 1 microM, a polydeoxyribonucleotide extracted from mammalian organs, reduced the contractile responses to noradrenaline (NA) in the rat isolated and perfused mesenteric vascular bed, in intact as well as in de-endothelialized preparations. Defibrotide was without effect on the acetylcholine-induced relaxations of U-46619-precontracted mesenteric vascular beds. Moreover, defibrotide increased 6-keto prostaglandin (PG) F(2alpha) (stable metabolite of prostacyclin) release sixfold in the presence, but not in the absence of the endothelium, with no modification on the release of other prostanoids. Defibrotide also inhibited the NA-induced increase in PGF(2alpha) release, in both intact and de-endothelialized mesenteric vascular beds. In conclusion, the present results show that defibrotide modulates PG production in the mesenteric bed and that the observed inhibition of the contractile responses should be due to the impairment of the NA-induced increase in PGF(2alpha) release.

Acetylcholine↗

PubMed1995

Defibrotide reduces monocyte PAI-2 and procoagulant activity.

Defibrotide is a polydeoxyribonucleotide-derived anti-ischemic drug with multiple sites of action involving both plasmatic and cellular targets. This agent has been demonstrated to produce profibrinolytic, cytoprotective, and vaso-facilatory actions. Since monocytes are increased in the mediation of some of the pathophysiologic responses seen in ischemic disorders, the functional properties of these cells were investigated in experimental conditions to evaluate their behavior during resting and stimulated states. Defibrotide was supplemented in these systems to determine its modulatory action. In this investigation Defibrotide was found to decrease the PAI-1 levels and may indicate that this may be the mechanism for its profibrinolytic actions. Defibrotide was also found to reduce the procoagulant activity of monocytes in these experimental settings. Both PAI and procoagulant factors play an important role in the pathophysiology of inflammation, DIC, and ischemia. Defibrotide induced reduction of these two factors represents the mechanism whereby this agent produces its therapeutic action.

Blood Coagulation Factors↗

PubMed1991

Absorption through the peritoneum of the macromolecular profibrinolytic drug defibrotide in the rabbit.

Defibrotide is the sodium salt of a polydeoxyribonucleotide extracted from mammalian lungs by controlled depolymerization. This macromolecular compound (mean molecular weight 20,000 d) has profibrinolytic activity. It also is antithrombotic after both intravenous and oral administration. The purpose of this study was to see whether defibrotide could activate the fibrinolytic system after intraperitoneal administration, because it has been observed that in ascitic patients treated intraperitoneally with defibrotide, no occlusion of the peritoneal-jugular catheter valve draining the ascitic fluid (according to LeVeen et al.) occurred. The profibrinolytic activity of defibrotide and its plasma levels were dose dependent, with a statistically significant correlation between the fibrinolytic activities and the AUC of the plasma levels of defibrotide. No rebound effect was observed during the duration of the experiments (24 hours). We hypothesize that the fibrinolytic activity elicited by defibrotide prevented the deposition of fibrin in the catheter valve, enabling normal drainage of the ascitic fluid. The lack of rebound makes defibrotide a safe drug. The mechanism by which this macromolecular compound is absorbed is still unknown.

Animals↗

PubMed1986

Reaction of nucleic acids and cis-diamminedichloroplatinum(II) in the presence of intercalating agents.

The reaction of cis-diamminedichloroplatinum(II) and several synthetic or natural double-stranded polydeoxyribonucleotides has been carried out in the presence of such intercalating agents as ethidium bromide, proflavine, and acridine. After incubation of the reaction mixtures at 37 degrees C for 24 hr, some ethidium or proflavine, but no acridine, molecules are tightly bound to nucleic acids. Tight binding is defined by resistance to extraction with butanol, assayed by filtration at acid pH or by thin-layer chromatography at basic pH. In the ternary complexes, there is about one tightly bound ethidium (or proflavine) per platinum residue. At 37 degrees C, but not at 4 degrees C, tightly bound ethidium exchanges with free ethidium, whereas platinum residues do not exchange. The binding and the release of tightly bound ethidium are very slow (several hours). It is suggested that in the ternary complexes, nucleic acid-cis-Pt(NH3)2-intercalating agent, a bidentate adduct (guanine-ethidium or -proflavine)-cis-Pt(NH3)2, is formed. No tightly bound ethidium or proflavine is found when cis-diamminedichloroplatinum(II) is replaced by trans-diamminedichloroplatinum(II). Competition experiments between cis-diamminedichloroplatinum(II), poly(dG-dC), and poly(dG)-poly(dC) or poly(dA-dT) show that the presence of ethidium bromide, proflavine, or acridine interferes with the distribution of platinum between the polynucleotides. These results might help to explain the synergism for drugs used in combination with cis-diamminedichloroplatinum(II) and in the design of new chemotherapeutic agents.

Acridines↗

PubMed1985

Comparison between poly(dG-dC).poly(dG-dC) and DNA modified by cis-diamminedichloroplatinum (II): immunological and spectroscopic studies.

The importance of the base composition and of the conformation of nucleic acids in the reaction with the drug cis-diamminedichloroplatinum(II) has been studied by competition experiments between the drug and several double-stranded polydeoxyribonucleotides. Binding to poly(dG).poly(dC) is larger than to poly (dG-dC).poly(dG-dC). There is no preferential binding in the competition between poly(dG-dC).poly(dG-dC), poly(dA-dC).poly(dG-dT) and poly(dA-dG).poly(dC-dT). In the competition between poly(dG-dC).poly (dG-dC) (B conformation) and poly(dG-br5dC).poly(dG-br5dC) (Z conformation), the drug binds equally well to both polynucleotides. In natural DNA, modification of guanine residues in (GC)n.(GC)n sequences by the drug has been revealed by the inhibition of cleavage of these sequences by the restriction enzyme BssHII. By means of antibodies to platinated poly(dG-dC), it is shown that some of the adducts formed in platinated poly(dG-dC) are also formed in platinated pBR322 DNA. The type of adducts recognized the antibodies is not known. Thin layer chromatography of the products after chemical and enzymatic hydrolysis of platinated poly(dG-dC) suggests that interstrand cross-links are formed. Finally, the conformations of poly(dG-dC) modified either by cis-diamminedichloroplatinum(II) or by trans-diamminedichloroplatinum (II) have been compared by circular dichroism. Both the cis-isomer and the trans-isomer stabilize the Z conformation when they bind to poly(dG-m5dC) in the Z conformation. When they bind to poly(dG-m5dC) in the B conformation, the conformations of poly(dG-m5dC) modified by the cis or the trans-isomer are different. Moreover, the cis-isomer facilitates the B form-Z form transition of the unplatinated regions while the trans-isomer makes it more difficult.

Binding, Competitive↗