Chitosan contribution on wool treatments with enzyme

In a previous research work, it was observed that the application of biopolymer chitosan (CHT) on wool fabrics before the enzymatic treatment promotes an increase of the weight loss. In order to deep on the role played by CHT, several experimental conditions have been selected according to a hybrid experimental design and different parameters, such as weight loss and shrink-resist properties, have been controlled. To enhance the CHT sorption on the wool fibre surface, wool was submitted previously to a water-vapour low-temperature plasma treatment. The weight loss results reveal that the enzyme effect increases by increasing the CHT concentration applied to untreated wool. However, CHT concentration does not have any influence when wool has been previously treated with plasma. It is deduced that the surface free energy of wool fibres plays an important role on the enzyme activity. Therefore, the results obtained reveal that the main contribution of CHT on hydrophobic surface of untreated wool fibres is to confer hydrophilicity to wool. Furthermore, CHT tends to coat the wool fibres by film formation reducing apparently the fibre damage promoted by enzyme treatment and also reducing the wool shrinkage.     

Cold microgradients elicit adaptive behavior in isotropically cooled, inert populations of Oxytricha bifaria (Ciliophora, Hypotrichida)

To complete our investigations on the oriented behavioral response of isotropically cooled, inert populations of Oxytricha bifaria to a warm thermal gradient, their physiological potentialities under cold microgradient conditions arising at 8.5 degrees C were studied. We monitored the behavior of the experimental populations, both at the level of the passing cold wave front, and afterwards when the thermal gradient stabilized, evaluating (i) their distribution in general, (ii) their relative centroids, (iii) the percentage of both backward creeping and immobile ciliates, and (iv) the numerical indices and rates of their creeping tracks. At the arrival of the cold wave front, the oxytrichas react immediately to the thermal stimulus, creep backwards at very high velocity along uninterrupted linear tracks, and thus move away from the cooling source. No specific behavioral response was ever observed in the static microgradient conditions. At 8.5 degrees C, despite their inertness, the ciliates are still able to behave adaptively, reacting immediately and orientatedly, once a directional factor (the cold-repelling thermal gradient) arises in an isotropic environment. This is similar to their behavior in the symmetric warm attracting thermal gradient.     

Linkage of proton binding to the thermal dissociation of triple helix complex

The effects of cytosine protonation on the thermodynamic properties of parallel pyrimidine motif DNA triplex were investigated and characterized by different techniques, such as circular dichroism (CD), ultraviolet spectroscopy (UV) and differential scanning calorimetry (DSC). A thermodynamic model was developed which, by linking the cytosine ionization equilibrium to the dissociation process of the triplex, is able to rationalize the experimental data and to reproduce the pH dependence of the free energy, enthalpy and entropy changes associated with the triplex formation. The results are useful to systematically introduce the effect of pH in a more general model able to predict the stability of DNA triplexes on the basis of the sequence alone.     

The locomotion of living organisms. Some hints for an evolutionistic reconsideration of biology's "foregone" topics.

From the analysis of the behaviour it is evidenced that the biological peculiarities of the Hypotrichs depend on the close linking between the adaptive strategies they have found to environmental problems. The loss of the envelope surface of the other ciliates was followed, in the Ciliates evolution, by the acquisition of the "cirrus and membranelle" propulsive logic. Furthermore they acquire a strong-and-easy-to-release adhesion system to creep on the substrate. The eco-ethological approach showed that they are capable of adapting to an environment characterised by new dimensional scales, new micro-environments and also new stimuli.     

Biophysical properties of quadruple helices of modified human telomeric DNA

Telomeric DNA of a variety of vertebrates including humans contains the tandem repeat d(TTAGGG)n. The guanine rich strand can fold into four-stranded G-quadruplex structures, which have recently become attractive for biomedical research. Indeed, the aptamers based on the quadruplex motif may prove useful as tools aimed at binding and inhibiting particular proteins, catalyzing various biochemical reactions, or even serving as pharmaceutically active agents. The incorporation of modified bases into oligonucleotides can have profound effects on their folding and may produce useful changes in physical and biological properties of the resulting DNA fragments. In this work, the adenines of the human telomeric repeat oligonucleotide d(TAGGGT) and d(AGGGT) were substituted by 2'-deoxy-8-(propyn-1-yl)adenosine (A-->APr) or by 8-bromodeoxyadenosine (A-->ABr). The biophysical properties of the resulting quadruplex structures were compared with the unmodified quadruplexes. NMR and CD spectra of the studied sequences were characteristic of parallel-stranded, tetramolecular quadruplexes. The analysis of the equilibrium melting curves reveals that the modifications stabilize the quadruplex structure. The results are useful when considering the design of novel aptameric nucleic acids with diverse molecular recognition capabilities that would not be present using native RNA/DNA sequences.     

Note: Microbial resistance of wool fabric treated with bis-Quats compounds

In this paper, the antibacterial activity against Bacillus pumilus, Staphylococcus aureus, Escherichia coli and Pseudomonas aeruginosa of the wool fabrics treated with new antimicrobial bis-quaternary surfactants, DABK and DABB, is studied. The activity was established on the basis of the agar diffusion and protective antibacterial test results and on the basis of scanning electron microscopy (SEM) observation. The results were compared with the HTAB, a monoquaternary surfactant of conventional use. The results from the agar diffusion and protective antibacterial tests do not enable us to confirm whether these compounds are potentially useful antimicrobial agents for the protection of textiles. However, SEM observations show clearly the efficacy of these compounds to protect the wool fabrics against the micro-organisms. SEM has been a useful technique for the assessment of antibacterial activity in textiles.     

Illustrations pratiques – Produits de contraste iodés (PCI)

Iodinated Contrast Agent (ICA) may be used in nuclear medicine for level 3 and 4 CT level. The use of ICA in SPECT/CT or PET/CT is driven, for each patient, by the clinical context, the benefit/risk ratio and the availability and the date of the previous injected CT. The improvement in diagnostic performance of the exam is the main goal of the ICA injection during a hybrid NM procedure.