SUMMARY Results are given of a preliminary research aimed at the molecular investigation of dryness of horse chestnut leaves incited by Guignardia aesculi and environmental pollution. Modifications due to pathology and physio- logical disorders are characterized. Leaves showing pathologies or a physiological disorder compared to sound leaves were investigated by FTIR Spectroscopy. The spectra showed a weakening of the aromatic do- main bands (1650-1500 cm -1 ) and intensity inversion of two bands of this domain (1650, 1610 cm -1 ) passing from the sound leaves to those affected with a physio- logical disorder. Moreover in the spectrum of these leaves, the 1300 cm -1 band disappears, the carbonylic esteric band (1730 cm -1 ) decreases while the band at 1400 cm -1 is enhanced probably because of partial hy- drolysis of the esteric groups. These bands could be a spectroscopic marker of the disease. The results show that FTIR spectroscopy is a promising technique helping to unravel the processes involving the biological macromolecules of plant tis- sues.

In this work calcium phosphate (CaP) compounds with different PO(3-)(4)/HPO(2-)(4) R molar ratios in the 0.65-149 range were synthesized. In fact, all these CaPs contain different amounts of HPO(2-)(4) and PO(3-)(4) ions as well as the amorphous precursors (tricalcium phosphate and octacalcium phosphate) of hydroxyapatite deposition, which was shown by in vitro and in vivo measurements. Spectroscopical IR and Raman results showed the presence of bands whose intensity ratio can be related to the molar ratio R; in particular, the Raman I(962)/I(987) and the IR I(1035)/I(1125) intensity ratios were characterized as markers of the molar ratio. For these CaP compounds a nucleation model, which was based on the ability of HPO(2-)(4) ions to form strong H bonds with PO(3-)(4) ions, was proposed.

In this work Raman microspectrometry was used to evaluate the crystallinity changes of hip cups made of ultra-high molecular weight polyethylene (UHMWPE). In vitro experiments were carried out using hip joint movement-wear simulators, run for five million cycles in water or bovine calf serum. The hip cups were subjected to mechanical friction with ceramic femoral heads (alumina–zirconia blend). The crystallinity of the polymer hip cups was studied as a function of inner surface position and thickness, from the stressed surface to the unstressed outer one. The Partial Least Square (PLS-l) calibration was used to correlate the Raman spectra with the crystallinity of the polymer measured with DSC calorimetry.

A reversed-phase high-performance liquid chromatographic technique for the determination of free amino acids in five biopsies of human brain tumors (two meningiomas, one glioblastoma and two oligodendrogliomas) is described. The frozen tissues were homogenized, deproteinized with perchloric acid and neutralized with potassium hydroxide. Aliquots of the supernatant containing the physiological amino acids are used for pre-column derivatization with phenylisothiocyanate. The derivatized PTC-amino acids (phenylthiocarbamyl derivatives) are stable for a five day period if stored as a powder at -20 degrees C in an inert atmosphere and they can be analyzed on a reversed-phase column (PicoTag) using a gradient of two eluents with absorption detection at a wavelength of 254 nm. Good resolution of several amino acids (>30) is achieved within ca. 60 min. For most amino acids this method is suitable for an accurate measurement over a wide range of physiological concentrations (50-400 pmol) starting from a very small amount of sample.

In this study an in vitro Magnetic Resonance Spectroscopic characterization of water soluble metabolites and the lipid fraction obtained from 31 tumors (14 glioblastomas, 3 anaplastic astrocitomas, 2 anaplastic oligodendrogliomas, 2 oligodendrogliomas and 10 meningiomas) is reported. The 1H MR spectrum of normal brain tissue is also shown, it is characterized by a low Cho/Cr signal intensity ratio and an intense NAA resonance. The regional metabolic heterogeneity of glioblastomas is documented. For these tumors, specific molecular composition by MRS cannot be defined. Oligodendrogliomas and anaplastic oligodendrogliomas showed typical Cho/Cr and Ala/Cr metabolite ratios. The degree of histological endothelial proliferation of the malignant astrocitomas and oligodendrogliomas was correlated to the presence of Cholesteryl esters in the 13C Magnetic Resonance spectrum of the lipid fraction obtained from these tumors. Meningiomas are mainly characterized by high Cho/Cr and Ala/Cr ratios.

Several derivatives of 1,3,5-triazine leg atrazine, prometryn) are effective herbicides and have been extensively used in agriculture. A study of prometryn (Prom)-phospholipid (PL), with different charges, was carried out by means of calorimetric and spectroscopic techniques. The Prom-dipalmitoylphosphatidylcholine (DPPC) and Prom-dipalmitoylphosphatidic acid (DPPA) water suspensions systems at pH values ranging from 5 to 9 were investigated. The results show that From does not significantly perturb the hydrophobic core of the lipid bilayer and suggest that the herbicide localizes near the glycerol backbone of the lipid, perturbing the environment of the carbonyls of the two ester groups. At pH 5 the vibrational band attributable to N-H stretch of From disappears thus suggesting that the absorption into the bilayer modifies the physicochemical properties of the herbicide. The two PL considered behave similarly and the effect of the charge is not noticeable. The strength of the Prom-PL interaction decreases with decreasing pH. (C) 1999 Society of Chemical Industry.

The FT-Raman and FT-IR spectra of amorphous 1:2.5 piroxicam (P): β-cyclodextrin (βCD) inclusion compound (PβCD) are presented and discussed in comparison with the spectra of the three main modifications of piroxicam (α,β and monohydrate). In the 1700–1200cm−1 FT-Raman spectrum of 1:2.5 PβCD inclusion compound the bands of βCD are weak and covered by those stronger of piroxicam, differently from the FT-IR spectrum where the bands of βCD are stronger, so covering a large part of the spectrum. Typical FT-Raman marker bands are assigned for the characterization of the three modifications of piroxicam. The FT-Raman spectrum of 1:2.5 PβCD inclusion compound predominantly shows the bands at about 1465 and 1400cm−1 of the monohydrate, indicating that piroxicam assumes the zwitterionic structure stabilized by interaction with βCD via electrostatic and hydrogen bonds. The dipolar character of 1:2.5 PβCD inclusion compound improves the solubility and the dissolution rate of piroxicam and thus its rate of absorption.

The results of a Raman and solid state 13C-NMR spectroscopic investigation aimed at studying the conformation of piroxicam (P) and its interaction with beta-cyclodextrin (betaCD) in 1 : 1 amorphous PbetaCD inclusion compound are reported. The 1700-1200 cm(-1) FT-Raman and the 13C CP/MAS NMR spectra of 1 : 1 PbetaCD inclusion compound are discussed and assigned in comparison with those of the three main modifications of piroxicam (alpha, beta, and monohydrate). The FT-Raman and 13C-NMR results show that in 1 : 1 PbetaCD inclusion compound piroxicam mainly assumes the zwitterionic structure typical of monohydrate, even if the presence of a different structure, that is, beta form, is not excluded. Piroxicam monohydrate, differently from alpha and beta forms, is characterized by a zwitterionic structure with an internal proton transfer and an increased charge delocalization, as shown by our spectroscopic results. The charge delocalization characteristic of this zwitterionic structure gives rise to the interaction with betaCD via electrostatic and hydrogen bonds. The possibility of a host-guest interaction between piroxicam and betaCD is not excluded; the guest molecule can be accommodated in betaCD cavity by interaction via hydrophobic bonds.

This study was focused on the conformational characterization of Bombyx mori silk fibroin in film, fiber and powder form by means of Fourier transform Raman spectroscopy. Native and regenerated silk fibroin films prepared by casting dilute silk fibroin solutions (<1%, w/v) display characteristic conformationally sensitive bands at 1660 cm(-1) (amide I), in the range 1276-1244 cm(-1) (a complex amide III region with multiple detectable maxima) and at 1107 and 938 cm(-1). This spectral pattern can be related to a prevalently random coil conformation, with traces of alpha-helix. Liquid silk, prepared by casting the silk gland content (fibroin concentration 20-25%, w/v), shows almost the same wavenumbers in the amide I and III ranges, while differences appear below 1000 cm(-1), where three bands at 952, 930 and 867 cm(-1) increase in intensity. The spectral differences between films and liquid silk are discussed with a view to identifying possible markers for silk I structure, a crystalline modification of silk fibroin. The treatment of both native and regenerated films with 50% (v/v) methanol solution induces the conformational transition to a beta-sheet structure, as demonstrated by the shift of amide I to 1665 cm(-1) and the appearance of new maxima at 1262 and 1236 cm(-1) (amide III) and at 1084 cm(-1). When liquid silk is cast at above 50 degrees C, the prevailing conformation taken by silk fibroin is beta-sheet, whatever the rate of drying. By comparing the Raman spectra of silk fibroin fiber and powder, both having a beta-sheet structure, a difference in the tyrosine doublet bands and in the amide I band can be observed. The value of the I-853/I-830 (R-tyr) intensity ratio increases in the powder while amide I shifts to lower wavenumbers, suggesting that the hydrogen bonds involving the tyrosil residues are weaker in the powder than in the fiber. (C) 1998 John Wiley & Sons, Ltd.

In this study we report an in vitro 1H magnetic resonance spectroscopy (MRS) characterization of water soluble metabolites obtained from 17 low grade extra and intracerebral human tumors (8 meningiomas, 5 oligodendrogliomas, 2 subependimomas and 2 ependimomas). In addition, the in vivo localized 1H MRS results for 4 of the meningiomas are reported. The main metabolic features characterizing low grade tumors were investigated. Meningiomas are characterized by high Cho/Cr and Ala/Cr ratios; in many cases both in the in vitro and the in vivo spectra these ratios cannot be evaluated, due to the absence of the Cr metabolite. Low grade oligodendrogliomas are characterized by low Cho/Cr ratios. High amounts of myo-inositol are found in the spectra of ependimomas and subependimomas which are distinguished by different Cho/Cr ratio values and by a different Ala content.