Self-deconvolution and the fourth derivative of ultraviolet absorption spectra have been used to study stacked single-stranded and double-helix structures of different cytosine-containing ...polynucleotides for the first time. These compounds were studied under different solution conditions (pH and organic solvents) and at low temperatures. The red shift of the lower band (B2u band plus possibly some n-->pi* transition) of the absorption spectra in the cytosine-containing polynucleotides and the appearance of new peaks in the deconvoluted and derivative spectra in the 280-310 nm region are attributed mainly to cytosine-cytosine stacking interactions. In particular, the fourth-derivative peaks at wavelengths higher than 290 nm can be associated to coupling of electronic transitions of cytosine bases. The nature of the electronic transitions producing the absorption bands which are resolved in the aforementioned fourth-derivative peaks is discussed. It is concluded that the resolution-enhancement techniques used in this work, i.e. self-deconvolution and fourth derivative, complement each other and are useful methods to study structural changes of single-stranded and double-stranded polynucleotides allowing, at the same time, more information to be obtained about specific stacking interactions than classical absorption spectrophotometry.
The conformational changes of polyd(A-C) times polyd(G-T) induced by Hg(ClO sub(4)) sub(2) in aqueous solution have been studied using UV absorption and fourth derivative spectrophotometries, and ...FTIR spectroscopy. The UV absorption and fourth derivative spectra reflect changes in the polynucleotide stacking interactions as a result of the metal-polynucleotide interaction. The fourth derivative spectra do not indicate a Z-form either at low or at high metal-to-polynucleotide ratios. Furthermore, the infrared spectrum at high metal-to-polynucleotide ratio (r = 1.2; r = Hg(ClO sub(4)) sub(2)/nucleotide molar ratio) has the main features of an A-form, in contrast with previous CD studies which proposed that the polynucleotide adopts a Z-form under these conditions. The nature of a different conformation of the polynucleotide induced at low r-ratios (r less than or equal to 0.2) is discussed.
Fourier transform-infrared spectroscopy has been used for the study of the secondary structure of arrestin from bovine retina rod cells. Spectra have been obtained in H2O and in D2O media. Resolution ...enhancement of the amide I secondary structure-sensitive overlapped component bands has been achieved by means of Fourier self-deconvolution and Fourier derivation. In order to obtain a quantitative estimation of the proportion of amino acid residues involved in each type of secondary structure, bands at the resolved frequencies have been curve-fitted to the deconvolved amide I contour by means of a least-squares best-fitting iterative program. The analysis of the results suggests that the secondary structure of arrestin comprises 56-63% of extended strands, 12-19% of turns and bends, 15% of alpha-helices and 10% of undefined and irregular segments.
The conformational changes of polyd(A-C)·polyd(GT) induced by Hg(CiO
4)
2 in aqueous solution have been studied using UV absorption and fourth derivative spectrophotometries, and FTIR spectroscopy. ...The UV absorption and fourth derivative spectra reflect changes in the polynucleotide stacking interactions as a result of the metal-polynucleotide interaction. The fourth derivative spectra do not indicate a Z-form either at low or at high metal-to-polynucleotide ratios. Furthermore, the infrared spectrum at high metal-to-polynucleotide ratio
(r = 1.2; r =
Hg(
ClO
4)
2
nucleotide molar ratio)
has the main features of an A-form, in contrast with previous CD studies which proposed that the polynucleotide adopts a Z-form under these conditions. The nature of a different conformation of the polynucleotide induced at low
r-ratios (
r < 0.2) is discussed.
The effect of the naturally occurring polyamines spermidine and spermine on poly(amino2-dA-dT).poly(amino2dA-dT) conformation has been studied by UV, CD, and IR spectroscopies. It is shown that a ...conformational transition is induced in poly(amino2dA-dT).poly(amino2dA-dT) by micromolar concentrations of the polyamines (30 microM) in low-salt aqueous solution. The analysis of our results, in view of previously published studies on conformational properties of the amino polynucleotide, indicates the resulting conformer to be an A-form. Interestingly, the polyamine concentration at the midpoint of the transition is the same in both cases. This provides further evidence that the coordination of positively charged counterions to DNA is determined largely from the DNA structure, probably with an important role for the sequence, and less from the nature of the ions.
Autologous adipose-derived stem cells may represent a novel approach for the management of complex fistula-in-ano. After successful phase I and II clinical trials, a phase III trial was performed to ...investigate the safety and efficacy.
In this multicenter, randomized, single-blind, add-on clinical trial, 200 adult patients from 19 centers were randomly assigned to receive 20 million stem cells (group A, 64 patients), 20 million adipose-derived stem cells plus fibrin glue (group B, 60 patients), or fibrin glue (group C, 59 patients) after closure of the internal opening. Fistula healing was defined as reepithelization of the external opening and absence of collection >2 cm by MRI. If the fistula had not healed at 12 weeks, a second dose (40 million stem cells in groups A and B) was administered. Patients were evaluated at 24 to 26 weeks (primary end point) and at 1 year (long-term follow-up).
All results are according to the "blinded evaluator" assessment. After 24 to 26 weeks, the healing rate was 39.1%, 43.3%, 37.3% in groups A, B, and C (p = 0.79). At 1 year, the healing rates were 57.1%, 52.4%, and 37.3 % (p = 0.13). On analysis of the subpopulation treated at the technique's pioneer center, healing rates were 54.55%, 83.33%, and 18.18%, at 24 to 26 weeks (p < 0.001). No SAEs were reported.
In treatment of complex fistula-in-ano, a dose of 20 or 60 million adipose-derived stem cells alone or in combination with fibrin glue was considered a safe treatment, achieving healing rates of approximately 40% at 6 months and of more than 50% at 1-year follow-up. It was equivalent to fibrin glue alone. No statistically significant differences were found when the 3 groups where compared.
www.clinicaltrials.gov, identifier NCT00475410; Sponsor, Cellerix SA.
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