Low molecular weight proteins in urines from healthy subjects as well as diabetic,nephropathic and diabetic‐nephropathic patients: a MALDI study

Urine samples from healthy subjects as well as diabetic, nephropathic and diabetic‐nephropathic patients were analyzed by matrix assisted laser desorption/ionization (MALDI) mass spectrometry in order to establish evidence of some possible differences in the peptide profile related to the pathological states. Multivariate analysis suggested the possibility of a distinction among the considered groups of patients. Some differences have been found, in particular, in the relative abundances of three ions at m/z 1912, 1219 and 2049. For these reasons, further investigation was carried out by MALDI/TOF/TOF to determine the sequence of these peptides and, consequently, to individuate their possible origin. By this approach, the peptide at m/z 1912 was found to originate from uromodulin, and its lower expression in the case of nephropathy can be well related to the pathological condition. Ions at m/z 2049 and 1219 originate from the collagen α‐1(I) chain precursor and from the collagen α‐5 (IV) chain precursor, respectively, and, also in this case, their different expressions can be related to the pathologies under investigation. The obtained data seem to indicate that urine is an interesting biological fluid to investigate on the peptide profile and to obtain, consequently, information on the dismetabolism activated by specific pathologies. Copyright © 2009 John Wiley & Sons, Ltd.     

ESR study of some solvent effects of the Cu(II)-aspirinate complex

Powder ESR spectra of the [Cu₂(Asp)₄](H₂O)₂ complex show the existence of Cu(II) acetate like dimers characterized by a strong antiferromagnetic exchange interaction (J=?288 cm^?1). In pyridine-dimethylformamide solutions the monomeric species prevail. Two different monomeric species, the Cu(DMF)₄ of planar-distorted tetrahedral (T_d) symmetry and the Cu(Asp)₂(DMF)₂ with elongated tetrahedral-octahedral symmetry were evidenced in DMF solution adsorbed on NaY zeolite. In 40 % Py+60 % DMF solution two monomeric species were also identified. These are Cu(Asp)₂(DMF)₂ and Cu(Asp)₂(Py)₂, the last species having a CuN₂O₂ chromophore in atrans squareplanar arrangement. In pyridine Cu(II)-aspirinate solution only the Cu(Py)₄ monomeric species of CuN₄ chromophore was evidenced.     

Effect of cyclodextrins on the physicochemical properties of chlorophyll a in aqueous solution

The interactions between chlorophyll a and two beta-cyclodextrins, that have the same cavity size but different substituents, were studied in aqueous solutions. These supramolecular host-guest complexes were examined by a combination of UV/vis absorption, circular dichroism, NMR, and steady-state and time-resolved fluorescence measurements. The results indicate that all cyclodextrins solubilize the pigment mainly in monomeric form in water. The pigment forms 1:1 complexes with the heptakis(2,3,6-tri-O-methyl)-beta-cyclodextrin and 1:2 complexes with the hydroxypropyl-beta-cyclodextrin. In such complexes the methyl groups of the cyclodextrin inner cavity are involved in the interaction with the pigment as evidenced by NMR measurements. We also measured the luminescence of singlet oxygen photosensitized by chlorophyll a in the inclusion complexes.     

Photophysical and electrochemical properties of chlorophyll a-cyclodextrins complexes

In this work, we have studied the interactions between two different cyclodextrins (CDs) and chlorophyll a (Chl a) in the presence of electrolyte by means of absorption, fluorescence spectroscopy, circular dichroism and cyclic voltammetry. The results obtained indicate that the presence of both CDs gives rise to an increase of Chl a solubility in water. In particular, heptakis-(2,3,6-tri-O-methyl)-beta-cyclodextrin (TRIMEB) favours the dissolution of Chl a monomer in aqueous solution, whereas the presence of hydroxypropyl-beta-cyclodextrin (beta-HP-CD) promotes the pigment aggregation.     

Effect of β-cyclodextrin on spectroscopic properties of ochratoxin A in aqueous solution

Ochratoxin A (OTA) is a nephrotoxic mycotoxin produced by several fungal species, mainly Aspergillus ochraceus, A. carbonarius and Penicillium verrucosum. It contaminates many foodstuffs, particularly cereals and their derivatives, coffee, beer, wine and cocoa, and represents a serious health threat both to humans and animals. Spectroscopic properties of OTA solutions depend on the pH, solvent polarity and can be influenced by the presence of cyclodextrins (CDs). In this work, the effect of β-CD on spectroscopic properties of OTA in aqueous solutions has been investigated by means of absorption and steady-state fluorescence at different pHs (range 3.5–9.5). Binding constants of OTA/β-CD inclusion complexes have been determined by applying modified Benesi-Hildebrand equation. A 1:1 stoichiometry of OTA/β-CD complexes has been observed at all tested pHs.     

Spectroscopic and magnetic investigation of one uranium(IV)-polyoxotungstate complex

The polyoxotungstate K₁₉[U₂KAs₄W₄₀O₁₄₀]^.42H₂O was synthesized and investigated by spectroscopic and magnetic susceptibility measurements. The IR spectrum of the complex contains the n_as(U–O)»1133 cm^–1 band due to the uranium coordination at {AsW₉} units and WO₆ binding octahedra. Electronic spectra indicate a ³H₄ ground state for the uranium(IV) in a quasicubic configuration. ESR spectra show a small orthorhombic distortion from the cubic symmetry (g _x = 2.045, g _y = 2.050, g _z = 2.085, D = 18.31^.10^{–4 .}cm^–1, E = 5.99^.10^{–4 .}cm^–1). The uranium ions are antiferromagnetically coupled for T>200 K (m_eff = 1.3 m_B at room temperature).     

Local structure analysis of Cu(II)-diazepam complexes by ESR spectroscopy

CuL(2)X(2) (L = 7-chloro-1,3-dihydro-1-methyl-5-phenyl-3H-1,4-benzodiazepin-2-one, also known as diazepam, X = Cl, Br) complexes have been prepared and investigated by ESR spectroscopy. Powder ESR spectra of these complexes suggest a planar-rhombic distorted local symmetry. The CH(3)Cl solutions spectra show the presence of pseudo-tetrahedral species with a 3d(xy)+4p(z) mixture ground state for the paramagnetic electron. The anisotropic spectra obtained for the Cu(II)-diazepam solution adsorbed on NaY zeolite confirm the existence of a CuN(2)X(2) chromophore.     

Random terpolymers for electroluminescent devices: Synthesis and characterization of new cyano‐containing poly(fluorenylene‐vinylene)s

The synthesis of new random poly(2,7‐fluorenylene‐vinylene)s was achieved by a Suzuki–Heck cascade polymerization reaction. The poly(fluorenylene‐vinylene) base structure was modified by the regio‐random incorporation of 1‐cyano‐2,5‐phenylene as electron withdrawing unit ( CN‐PFV1 ) and its properties were compared with terpolymers also embodying 1,4‐dioctyloxy‐2,5‐phenylene ( CN‐PFV2 ) or 3,6‐N‐octylcarbazole ( CN‐PFV3 ) as electron‐donating moieties. Thermal analysis revealed a high thermal stability (T_d > 389 °C) and the absence of glass transitions for all polymers. Cyclic voltammetry indicated a high electron affinity of the materials (2.96–3.21 eV) attributed to the presence of the cyano‐containing comonomer. In dilute solutions, the copolymers showed a broad green fluorescence with quantum yields ranging from 0.42 to 0.79, while in the solid state, a relatively narrow emission centered at ～ 560 nm, governed by the low‐energy segments within the π‐conjugated backbone, was observed. The electroluminescence properties of the materials were tested in OLED devices of ITO/PEDOT‐PSS/ CN‐PFV1‐3 /Ca/Al or ITO/PEDOT‐PSS/ CN‐PFV1‐3 /Alq₃/Ca/Al configurations, showing a bright green‐yellow emission that, in the case of CN‐PFV2 , reached 1403 cd/m² with efficiencies as high as 0.13 cd/A. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 6051–6063, 2008     

A further investigation on a MALDI‐based method for evaluation of markers of renal damage

The validity of the urinary protein profile to characterize the pathological states of diabetic, nephropathic and diabetic–nephropathic patients was considered on the basis of previously obtained results by MALDI/MS, showing a different abundance ratio of the collagen α1 and α5 chain precursor fragments at m/z 1219 and 2049 and of the uromodulin precursor fragment at m/z 1912 observed in healthy subjects and patients; a larger number of subjects was examined and the obtained results were statistically evaluated. The p values related to the observed differences indicate that they are statistically significant when comparing all patients versus healthy controls, diabetic with normo or microalbuminuria versus nephropathic with advanced renal disease patients and diabetic with normo or microalbuminuria versus diabetic with advanced nephropathy patients. The scatter plot matrix gives evidence of the strict inverse relationship between the abundances of ions at m/z 1912 and 1219, the correlation coefficient being particularly high (r = 0.921, p < 0.001). The relationship between the true positive rate (sensitivity) and false positive rate (1—specificity) for every possible cutoff value in abundance of the considered ionic species was investigated through the receiver‐operating characteristic (ROC) curve. The obtained data indicate that a good differentiation of nephropathic patients with advanced renal disease and diabetic patients with advanced nephropathy versus healthy subjects can be easily obtained by this approach. Copyright © 2009 John Wiley & Sons, Ltd.