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Results for “Base Composition”

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At least 703 records · Page 39Linked to original sources
PubMed1975

Number of genes and base composition of mitochondrial tRNA from Saccharomyces cerevisiae.

Increasing amounts of mitochondrial [32P] tRNA (4S fraction), were hybridized with mitochondrial DNA OF Saccharomyces cerevisiae. At saturation, the calculated number of genes for 4S mitochondrial RNA was 20. Mitochondrial [32P] tRNA eluted from the hydrids obtained either with an excess of tRNA or an excess of DNA showed, after alkaline hydrolysis and chromatography, a G+C content of 28 and 35 p. cent respectively. This last value is similar to that found with the total 4S fraction. The odd nucleotides T (about 1T per sequence), U, hU are present in mitochondrial tRNA. Some sequence may begin with pG.

Autoradiography↗
PubMed1976

Base composition heterogeneity of mammalian DNAs in CsCl-netropsin density gradient.

DNAs of 15 mammals and some lower organisms were analysed by CsCl-netropsin density gradient centrifugation. Increased resolving power of this method enabled to detect many new components in mammalian DNAs. Distinct components were detected in the density range of the main band. These components found in different mammalian DNAs have probably limited variation in the G+C content. Most of other components seems to be species specific. The DNAs of lower organisms form homogeneous band even in the presence of netropsin. The relation between densities in CsCl-netropsin and CsCl density gradient is nonlinear. This result supports a hypothesis that in high ionic strength netropsin is preferentially bound to (dA.dT) clusters.

Animals↗
PubMed1985

Alcohol induced B-A transition of DNAs with different base compositions studied by circular dichroism.

The circular dichroic (CD) spectra of natural DNAs (from Cl. perfringens, T2 phage, calf thymus, E. coli, and M. lysodeikticus) as well as duplexes of synthetic DNAs (poly(dA) X poly(dT), poly(dA-dT), and poly(dG-dC] were measured in water-ethanol mixtures with 0.3 mM NaCl. A conformational change from the B to the A form was observed for the natural DNAs on adding ethanol. The ethanol concentration that induces the transition and the extent of the change in the CD spectrum are different for the five natural DNAs depending on their GC contents. The higher the GC content is, the more easily the transition to the A form takes place. The results indicate that the GC content of a DNA is an important factor for induction of the B-A transition. The results for the synthetic DNAs show that their properties cannot be inferred by simple extrapolation of those of natural DNAs. Coexisting ions and the molecular weight of a DNA were also found to affect the induction of the B-A transition.

Animals↗
PubMed1991

Orbital augmentation by hydroxylapatite-based composites. A rabbit study and comparative analysis.

Hydroxylapatite, a synthetic bone mineral, was implanted alone or as a composite with either calcium sulfate (plaster of Paris) or Avitene (microfibrillar collagen hemostatic agent) into the orbital bony defects and orbital soft tissues of 23 rabbits. Plain Avitene was also placed into these bony and soft tissue sites and bone defects with no additives served as controls. Additionally, each implant material was placed into subcutaneous tissues to determine its relative inflammatory potential. New bone formation was noted in bony defects as early as 10 days. Bone ingrowth was greatest when hydroxylapatite was in direct apposition to bone. Material implanted away from bone showed predominantly connective tissue ingrowth. Minimal inflammatory reaction was noted early on in the hydroxylapatite and hydroxylapatite/calcium sulfate samples and had resolved by 2 months when placed in both soft and bony tissues. Samples of Avitene and the hydroxylapatite/Avitene composite demonstrated an intense inflammatory response, and in several cases large granulomas were seen after 2 months.

Animals↗
PubMed2004

Comparison of a plasma-based composite biologic sealant with fibrin glue (Tisseel) for vascular anastomoses.

Biologic sealants are needed in numerous, more and more demanding, procedures--especially with developments occurring in endovascular and laparoscopic vascular techniques. An initial pilot study in dogs showed that a 4-cm aortotomy closed with a polyester patch sutured in place by a 4-mm-spaced running suture consistently led to massive hemorrhage. We then designed a study using five dogs where two aortotomies were done to compare the effect of Tisseel to that of an autologous sealant prepared in our laboratory. Arterial pressures and heparinization were maintained throughout the surgical procedure. Both biologic sealants prevented hemorrhage from the arteriotomy at unclamping. Macroscopic and histologic assessments were performed. At killing, one week later, the autologous sealant exhibited less blood saturation of the collagen sponge compared with Tisseel. The use of autologous plasma combined with other adhesive components could be an efficient alternative to allogenic fibrin glue. Further studies are needed to confirm these observations.

Fibrin Tissue Adhesive↗