UVB radiation induced effects on cells studied by FTIR spectroscopy

We have made a preliminary analysis of the results about the effects on tumoral cell line (lymphoid T cell line Jurkat) induced by UVB radiation (dose of 310 mJ/cm²) with and without a vegetable mixture. In the present study, we have used two techniques: Fourier transform infrared spectroscopy (FTIR) and flow cytometry. FTIR spectroscopy has the potential to provide the identification of the vibrational modes of some of the major compounds (lipid, proteins and nucleic acids) without being invasive in the biomaterials. The second technique has allowed us to perform measurements of cytotoxicity and to assess the percentage of apoptosis. We already studied the induction of apoptotic process in the same cell line by UVB radiation; in particular, we looked for correspondences and correlations between FTIR spetroscopy and flow cytometry data finding three highly probable spectroscopic markers of apoptosis (Pozzi et al. in Radiat Res 168:698–705, 2007). In the present work, the results have shown significant changes in the absorbance and spectral pattern in the wavenumber protein and nucleic acids regions after the treatments.     

Differential response to hepatic differentiation stimuli of amniotic epithelial cells isolated from four regions of the amniotic membrane

Human Amniotic Epithelial Cells (hAEC) isolated from term placenta are a promising source for regenerative medicine. However, it has long been debated whether the hAEC population consists of heterogeneous or homogeneous cells. In a previous study, we investigated the characteristics of hAEC isolated from four different regions of the amniotic membrane finding significant heterogeneity. The aim of this study was to evaluate the hepatic differentiation capability of hAEC isolated from these four regions. Human term placentae were collected after caesarean section and hAEC were isolated from four regions of the amniotic membrane (R1-R4, according to their relative distance from the umbilical cord) and treated in hepatic differentiation conditions for 14 days. hAEC-derived hepatocyte-like cells showed marked differences in the expression of hepatic markers: R4 showed higher levels of Albumin and Hepatocyte Nuclear Factor (HNF) 4α whereas R1 expressed higher Cytochrome P450 enzymes, both at the gene and protein level. These preliminary results suggest that hAEC isolated from R1 and R4 of the amniotic membrane are more prone to hepatic differentiation. Therefore, the use of hAEC from a specific region of the amniotic membrane should be taken into consideration as it could have an impact on the outcome of therapeutic applications.     

Identification and purification of overlapping cosmid clones of the region Xq24-qter of human X chromosome using HPLC.

The assembly of a large physical map of genomes requires simultaneous analysis of many cosmid clones for overlapping regions. The search for overlapping regions may be achieved by various means. High-performance liquid chromatography (HPLC) provides an alternative to gel electrophoresis since microgram amounts of each DNA fragment may be collected into individual test tubes for further analysis. HPLC has been used to identify overlapping cosmid clones from a pool of cosmid DNA containing the terminal portion of the long arm of the human X chromosome (Xq24-qter). Among 400 cosmids analyzed, 3 were shown to overlap.     

Intramolecularly hydrogen-bonded peptide conformations

Over the past few years the possible occurrence of intramolecularly hydrogen-bonded structures in linear and cyclic peptides has attracted increasing attention. In this review emphasis is given to solid-state studies, particularly by X-ray diffraction and infrared absorption techniques. Conformational energy calculations are also considered. The discussion is focused both on model peptides and biological activity polypeptide molecules. The tetrapeptide system (Formula: see text), examined allows one to discuss the extended C5 structure and the various folded conformations, namely the C7 (gamma-turn), C8, C10 (beta-turn), C11, and C13 conformations. The four latter forms may include cis peptide configurations. The oxy-analogs to the C7, C10, and C13 conformations and structures containing bifurcated hydrogen bonds are also discussed. The last sections describe intramolecularly hydrogen-bonded peptide structures involving: (1) a side-chain group, (2) the N-protecting group (in synthetic model compounds), and (3) a beta-amino acid.     

Influence of Particle Size and Concentration on Rheological Behaviour of Reconstituted Apple Purees

This work investigates the impact of structural parameters on the rheological behaviour of apple purees. Reconstructed apple purees from 0 g/100 g up to 2.32 g/100 g of insoluble solids content and varying in particle size were prepared. Three different particle size distributions were obtained by mechanical treatment only, to modify both size and morphology of the particles without modifying the intrinsic rigidity of the cell walls. Rheological measurements showed that the insoluble solids content have a first order effect on the rheological behaviour of the suspensions: three concentrations domains were observed in both dynamic and flow measurements. A model is proposed for each domain. The existence of a weak network between particles is clearly shown over a critical concentration of insoluble solids (cell walls) depending on particle size distribution (semi-diluted domain). In a concentrated domain, particles are on close packing conditions and their apparent volume begin to shrink. Particle size and shape also play an important role on the rheological behaviour of reconstructed apple puree. Due to their irregular shape, cell clusters clog the medium at lower concentration compared to individual cells.     

Allylic palladium(II) triazenido complexes: synthesis and spectroscopic studies

Reaction of [Pd(1-3-η-allyl)Cl]₂ with lithium triazenide (triazenide = p-XC₆H₄NN-NC₆H₄X-p; X = Cl, H, CH₃) affords dimeric complexes of the type [Pd(1-3-η-allyl)(triazenide)]₂. In the solid state the triazenido ligands are bridging two palladium atoms with their terminal nitrogen atoms, as shown by a preliminary X-ray determination of the complex with X = CH₃. The allyl groups are stereochemically equivalent. ¹H NMR spectra demonstrate the presence of two conformers in solution. The major component has the same configuration found in the solid. The other conformer has stereochemically non equivalent allyl groups. The concentration ratio of the two conformers is independent of the temperature, suggesting the absence of intramolecular processes and of palladium- triazenido bond breaking. This point is discussed also by comparing the (1-3-η-allyl)(triazenide)palladium (II) dimers with the closely related(1-3-η-allyl)(acetate)palladium(II) complexes.     

Conformational aspects of polypeptides. XXIX. Conformational assignments for some aromatic polypeptides by far-UV Cotton effects. New results

Recent improvements in apparatus permit the examination of circular dichroism (CD) and optical rotatory dispersion (ORD) spectra to 185 mμ. In addition, new solvents which are transparent to 185 mμ have become available for synthetic polypeptides. The spectral region 185–250 mμ is extremely important for the amide (peptide) chromophore, because of the presence at these wavelengths of the n–π* and π–π* bands,¹ and of another transition, the assignment of which remains unsettled.²     

Energy-dependent formation of free ATP in yeast submitochondrial particles, and its stimulation by oligomycin

Yeast submitochondrial particles, in a P_i- and NADH-dependent reaction, produced low concentrations of free ATP in the absence of added ADP. This formation of free ATP, as measured by the luciferin-luciferase method, was strongly stimulated by oligomycin. For maximal stimulation, oligomycin was to be added not earlier than 5–10 min after the addition of NADH. Upon addition of antimycin or FCCP the system was completely inhibited. The amount of free ATP formed corresponded to one-third of the amount of bound ATP in submitochondrial particles. The stimulatory effect of oligomycin disappeared if the submitochondrial particles were spun down after oligomycin stimulation and then resuspended in the reaction medium, whereas submitochondrial particles with no oligomycin added initially were stimulated by oligomycin after the same procedure. A different picture emerged with addition of ADP. If the submitochondrial particles were preenergized with NADH in the presence of oligomycin before the addition of ADP the formation of free ATP upon subsequent addition of ADP was inhibited by oligomycin. In the presence of oligomycin, but lacking preenergization with NADH, a stimulation of free ATP formation was achieved with added ADP. A possible explanation for the stimulating effect of oligomycin on ATP formation in the absence of added ADP is that it enhances the release of bound ATP in an energy-requiring process. The release of only about one-third of the bound ATP could indicate that one of three nucleotide-binding subunits involved in the mechanism of ATP formation by ATP synthase is in a state suitable for such an energy-dependent release of ATP.