2-amino-1-propanol versus 1-amino-2-propanol: valence band and C 1s core-level photoelectron spectra.

Valence band and C 1s core-level photoelectron spectra of S-(+)-2-amino-1-propanol (alaninol) and S-(+)-1-amino-2-propanol (isopropanolamine) have been studied by means of synchrotron radiation photoelectron spectroscopy in gas phase. The alaninol, the reduced derivative of the alanine, is a good test system of amino acid-like structures. The isopropanolamine, presenting the inversion of the two functional groups of the alaninol at the chiral carbon, offers the opportunity to study the effect of -OH and -NH(2) structural position on the photoelectron spectra. The influence of the conformational contribution on the electronic structure and the photoelectron spectra has been interpreted using density functional and ab initio theoretical calculations. Agreement has been achieved by taking into account the presence, in gas phase, of two conformers with different population ratios in both chiral systems. The C 1s core-level spectra of alaninol and isopropanolamine are reported and the peak positions of the three carbon atoms of the molecules are assigned.

Spin-flop ordering from frustrated ferro- and antiferromagnetic interactions: a combined theoretical and experimental study of a Mn/Fe(100) monolayer.

The occurrence of a noncollinear magnetic structure at a Mn monolayer grown epitaxially on Fe(100) is predicted theoretically, using spinor density-functional theory, and observed experimentally, using x-ray magnetic circular dichroism (XMCD) and linear dichroism (XMLD) spectroscopies. The combined use of XMCD and XMLD at the Mn-absorption edge allows us to assess the existence of ferromagnetic and antiferromagnetic order at the interface, and also to determine the moment orientations with element specificity. The experimental results thus obtained are in excellent agreement with the magnetic structure determined theoretically.

[Anti-Pseudomonas aeruginosa antibodies, circulating immune complexes, and anticytoplasm antibodies of neutrophils in patients with cystic fibrosis with and without Pseudomonas aeruginosa colonization]. / Anticorpi anti-Pseudomonas aeruginosa, immunocomplessi circolanti ed anticorpi anticitoplasma dei neutrofili in pazienti affetti da fibrosi cistica colonizzati e non da Pseudomonas aeruginosa.

Chronic lung infections, mainly due to Pseudomonas aeruginosa (Pa), account for the most of the morbidity and mortality in CF patients. The pathogenic factors predisposing to airway colonization are still nuclear. Host's immune response is not only poorly protective but can also act as a damaging factor in the development of the disease. Moreover, clinical manifestations of an overactive immune response, including vasculitis and arthropathy, have been recently described in the CF population. To deepen factors involved in the pathogenesis of lung injury, we evaluated the presence of anti-Pa precipitating antibodies, circulating immune complexes (CIC) and antineutrophil cytoplasmic antibodies (ANCA) in sera from 50 CF patients colonized and not by Pa. Number of anti-Pa precipitins was significantly different in chronically and in not colonized patients (p < 0.001; t = 7.75). Anti-Pa antibodies were positively correlated to age (p = 0.002, r = 0.42) and inversely correlated to lung function parameters (p = 0.031 r = -0.35 with respect to FVC). Mean C3-CIC levels in the sera were statistically higher in chronically colonized patients (p = 0.013; t = 2.57); while there was not a significant difference with respect to C1q-CIC values. Four patients, all chronically colonized by Pa, were ANCA-positive at indirect immunofluorescence, showing a cytoplasmic pattern. All 50 patients were found to be negative when tested for anti-mpo and anti-pr3 antibodies with ELISA. In conclusion, our data demonstrate that persistence of Pa provides a stimulus for chronic inflammation and the immune response in CF patients, leading to anti-Pa antibodies and CIC production. Even in the face of further research, we speculate that c-ANCA production is secondary to neutrophil activation with a consequent release of cytoplasmic enzymes that perpetuate and increase the inflammatory process. Since anti-mpo and anti-pr3 antibodies rarely occur in CF patients we suggest that other antigenic specificities may be involved in ANCA production.

Some anti-thyroperoxidase antibodies positive sera give a pANCA pattern on ethanol-fixed human neutrophils: cross-reactivity or false positives?

Fifty-six sera from patients with autoimmune thyroiditis and 33 sera from patients with MPO-ANCA were examined in order to ascertain whether a cross reactivity between MPO-ANCA and anti-thyroperoxidase (aTPO) was present. Sera from 20 healthy donors aTPO and aMPO negative were used as control. About 95% of heat inactivated sera from patients with autoimmune thyroiditis and from controls gave positive results (atypical pANCA pattern) on ethanol-fixed neutrophils. The prevalence of positive results was significantly lower when unheated aTPO positive sera were used (17.8%). On the other hand, only 9% of sera with MPO-ANCA were positive on cryostatic sections of human thyroid. Indirect immunofluorescence tests (IF) on human neutrophils with MPO defect were negative with sera from patients with MPO-ANCA, but uninactivated sera with aTPO and positive for pANCA on normal neutrophils showed a very high prevalence of positive results (90%). According to our data only few sera positive for aTPO recognize "normal" MPO, but the majority of sera from patients with autoimmune thyroiditis and positive for pANCA on normal neutrophils recognize also an "abnormal" MPO. On the other hand MPO-ANCA usually recognize epitopes presently only on the normal enzyme, a small proportion of these autoantibodies can react with TPO. Heat inactivated sera give false positive results for pANCA on ethanol fixed human neutrophils.