Hydrophilic/hydrophobic features of TiO2 nanoparticles as a function of crystal phase, surface area and coating, in relation to their potential toxicity in peripheral nervous system.

The hydrophilic/hydrophobic properties of a variety of commercial TiO(2) nanoparticles (NP), to be employed as inorganic filters in sunscreen lotions, were investigated both as such (dry powders) and dispersed in aqueous media. Water uptake and the related interaction energy have been determined by means of adsorption microcalorimetry of H(2)O vapor, whereas dispersion features in aqueous solutions were investigated by dynamic light scattering and electrokinetic measurements (zeta potential). The optimized dispersions in cell culture medium were employed to assess the possible in vitro neuro-toxicological effect on dorsal root ganglion (DRG) cells upon exposure to TiO(2)-NP, as a function of crystal phase, surface area and coating. All investigated materials, with the only exception of the uncoated rutile, were found to induce apoptosis on DRG cells; the inorganic/organic surface coating was found not to protect against the TiO(2)-induced apoptosis. The risk profile for DRG cells, which varies for the uncoated samples in the same sequence as the photo-catalytic activity of the different polymorphs: anatase-rutile>anatase>>rutile, was found not to be correlated with the surface hydrophilicity of the uncoated/coated specimens. Aggregates/agglomerates hydrodynamic diameter was comprised in the ~200-400 nm range, compatible with the internalization within DRG cells.

Entrapping molecules in zeolites nanocavities: a thermodynamic and ab-initio study.

Adsorption enthalpies of Ar, N2, CO, H2O, CH3CN and NH3 on H-BEA and H-MFI zeolites and on Silicalite, have been measured calorimetrically at 303K in order to assess the energetic features of dispersive forces interactions (confinement effects), H-bonding interactions with surface silanols and specific interactions with Lewis and Brønsted acidic sites. The adsorption of the molecular probes with model clusters mimicking surface silanols, Lewis and Brønsted sites has been simulated at ab-initio level. The combined use of the two different approaches allowed to discriminate among the different processes contributing to the measured (-deltaadsH). Whereas CO and N2 single out contributions from Lewis and Brønsted acidic sites, Ar is only sensitive to confinement effects. For H2O, CH3CN and NH3 the adsorption on Brønsted sites is competitive with the adsorption on Lewis sites. The energy of interaction of H2O with all considered zeolites is surprisingly higher than expected on the basis of -deltaadsH vs PA correlation.

An Italian national multicenter study for the definition of reference ranges for normal values of peripheral blood lymphocyte subsets in healthy adults.

BACKGROUND AND OBJECTIVE: Reference ranges are necessary in clinical chemistry and hematology to compare an observed value and to provide meaningful information. The aim of this multicenter study was the definition of reference ranges of the relative and absolute numbers of lymphocyte subsets by evaluating a large cohort of healthy adults and by using a standard protocol to reduce the variability in both sample preparation methodology and flow cytometer operation. Other aims of this study were the evaluation of the influence of sex, age, obesity, smoking, sport and some methodological variables on lymphocyte subsets and the comparison of differential white blood cell values obtained by flow cytometry and those obtained by hematology counters. DESIGN AND METHODS: Blood samples from 1311 healthy adults (blood donors and volunteers chosen according to the Italian law for donor selection) were analyzed to study, by flow cytometry, the immunophenotype of lymphocyte subsets and their distribution in terms of percentages and absolute values. Pre-analytical and analytical phases were performed according to the guidelines of the International Federation of Clinical Chemistry (IFCC) and the Italian Group of Cytometry (GIC). T cells were defined by the expression of CD3; T subpopulations by the coexpression of CD4 or CD8 or HLA-DR; B-lymphocytes were identified by the expression of CD19 while natural killer lymphocytes were identified by positivity of CD16 and/or CD56 without CD3. We calculated, for each laboratory and for all data collected, the frequency distribution percent values and absolute values of each lymphocyte subset. The influence of age, sex, smoking, obesity and sport was calculated by the t-test. The influence of some methodological variables was calculated by the t-test and multiple regression test. RESULTS: Fifty-three flow cytometry laboratories at different institutions in Italy participated in this study. Data was obtained from 1311 healthy adults aged from 18 to 70; 968 phenotype analyses (74%) were considered eligible for statistical analysis. Significant results were found as regards sex, smoking and some methodological variables (quantity of sample, washing procedures, brand of monoclonal antibodies and kind of instruments used). The comparison between hematology counters and cytometers showed no difference for any of the parameters considered. INTERPRETATION AND CONCLUSIONS: The large number of cases, the different kinds of laboratories and their distribution throughout the country make our sample representative of the Italian adult population. The standardization criteria of pre-analytical and analytical phases (the most important issues in evaluating reference values for an indicator) assured good reproducibility among laboratories so that the obtained reference ranges may be useful for interlaboratory comparison of results. Instruments and the brand of monoclonal antibodies may represent an inevitable cause of variability.

Physicochemical properties of crystalline silica dusts and their possible implication in various biological responses.

The effect of grinding, heating, and etching was investigated on polymorphs of silicon dioxide exhibiting different biological responses. Diatomaceous earths were converted into cristobalite at 1000 degrees C. Dusts obtained by grinding crystalline minerals exhibited different micromorphology and a propensity to originate surface radicals which decrease in the sequence cristobalite --> quartz --> coesite --> stishovite. The production of surface radicals was suppressed by grinding in the presence of water. Thermal treatments selectively quenched the radicals and decreased surface hydrophilicity. Quartz treated with aluminum lactate exhibited higher surface acidity when compared with pure quartz, with a reduction in fibrogenicity. Etching by hydrofluoric acid smoothed the particles with loss of specific surface. Adsorption of water on three cristobalite dusts of different origin (ground mineral, ex-diatomite, heated quartz) indicated a loss in heated quartz (1300 degrees C) that was relatable to the corresponding reduction in fibrogenicity.

[An etiological definition of a case of mixed pneumoconiosis due to silicates and coal in the absence of anamnestic data]. / Definizione etiologica di un caso di pneumoconiosi mista da silicati e carbone in assenza del dato anamnestico.

A case of pneumoconiosis with unknown occupational history was examined both pathologically and mineralogically by means of a variety of techniques, including analytical scanning and transmission electron microscopy with electron diffraction and energy dispersive x-ray analysis, and electron resonance spectroscopy. The pathologic features consisted of a diffuse interstitial fibrosis with deposits of amorphous and crystalline particles and granulomatous reaction. The identification of minerals, mainly talc, halloysite, coal and chlorite, allowed a definite diagnosis of mixed silicate pneumoconiosis to be made. This is an example of complete pathologic, mineralogic and physico-chemical analysis of a case of pneumoconiosis.

What is the relationship between hemolytic potential and fibrogenicity of mineral dusts?

The hemolytic reaction to a dust is often used as a potential indicator of fibrogenicity of silicon dioxide polymorphs. However, occasionally the hemolytic response may not correlate with the observed fibrotic response in vivo. For example, amorphous silicas are very hemolytic but have little or no fibrogenic activity. In our study, heat treatment was used to alter alpha-cristobalite, a known fibrogenic dust, to a more hydrophobic surface. Comparisons were made between heated and unheated alpha-cristobalite for hemolytic activity in vitro and for lung response in vivo. Heat treatment resulted in decreased hemolytic response, but no change in the fibrotic response occurred in vivo. In addition, the heat treatment resulted in increased initial dust accumulation, reduced short-term clearance, and enhanced long-term clearance in vivo. Increased inflammatory cell recruitment was also observed in lungs of animals exposed to alpha-cristobalite. Thus, whereas heat-induced surface changes in alpha-cristobalite markedly altered the hemolytic activity of the particles, no changes were observed in the fibrotic response.

Chemical functionalities at the silica surface determining its reactivity when inhaled. Formation and reactivity of surface radicals.

Reactive radicals at the surface of quartz or other SiO2 polymorphs have been studied by EPR in relation to their possible role in pathogenicity. All the examined dusts bear the characteristic radicals of silica ground in air: Si, SiO., SiO.2 (peroxyradical) and O2.- (superoxide ion), but some also show additional spectral lines belonging to other radical forms. Comparison of standard quartz dusts (DQ-12, Min-u-sil 5) with a natural quartz and with what obtained by grinding a very pure quartz crystal indicates that to a higher purity corresponds a higher radical population. Cristobalite and vitreous silica exhibit similar spectra, with larger proportion by respect to quartz, of partially reduced oxygen forms. The reactivity of the silica surface towards O2 and NaClO aqueous solutions are investigated by examining the modification in the EPR spectra induced by these treatments. A possible mechanism for fibrogenicity is proposed whereby, within the activated macrophage, a catalytic reaction occurs between surface functionalities and macrophage oxygen metabolites. This reaction would trigger the abnormal production of fibroblast stimulating factors, ending up with silicosis.