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A model for the alkali metal bonding energy in some solid oxides based on a simplified approach of the electronegativity equalization method is proposed. From this model, no intensive numerical cal...

OBJECTIVES--To compare the usefulness of high resolution computed tomography (HRCT) with chest radiography (CR) in the diagnosis and assessment of severity of silicosis. METHODS--27 workers exposed to silica underwent CR, HRCT, and pulmonary function tests. Two experienced readers independently evaluated CR by International Labour Office classification, and grouped the results into four categories. HRCT categories of nodule profusion and the extent of emphysema were graded on a four point scale; in 20 subjects the percentage distribution of lung densities were measured by HRCT. RESULTS--Concordance between readers was higher for HRCT than for CR (K statistic = 0.49 and 0.29 respectively). There was poor concordance between CR and HRCT in the early stage of silicosis. No significant difference in pulmonary function tests was found among different CR categories, but forced expiratory volume in one second (FEV1), maximal expiratory flow at 50% and 75% of FVC (MEF50, MEF75), and diffusion capacity significantly decreased with increasing HRCT categories. Subjects with simple silicosis detected by HRCT had a lower FEV1 than subjects without silicosis, whereas subjects with conglomerated silicosis showed higher residual volume and functional residual capacity than subjects with simple silicosis. These relations were not affected by smoking or symptoms of chronic bronchitis. Different grades of emphysema detected by HRCT were significantly different in diffusion capacity. Only the HRCTs of the lowest and the highest categories of profusion of parenchymal opacities were significantly different in their distribution of density classes. CONCLUSION--HRCT is more reproducible and accurate than CR, as suggested by the higher agreement between readers and the better correlation with pulmonary function tests, irrespective of smoking and chronic bronchitis; however, these data do not support the hypothesis that HRCT is more sensitive than CR in the early detection of silicosis.

Hypertonic saline-induced sputum has recently been used for the evaluation of airway inflammation in asthma.To assess the effect of hypertonicity on airway inflammation.We compared the inflammatory cell composition of hypertonic saline-induced sputum with that of isotonic saline-induced sputum in 21 asthmatic subjects and, at baseline and 30 min after each sputum induction, we measured bronchial hyper-responsiveness to methacholine as an indirect marker to detect increased airway inflammation. On two different days, the patients inhaled hypertonic saline (3-5% NaCl) or isotonic saline (0.9% NaCl) for 30 min via an ultrasonic nebulizer, while monitoring FEV1. Sputum was collected for inflammatory cell analysis.There was no difference in inflammatory cell percentages obtained with the two methods. Eosinophils were1% in 20 subjects after hypertonic saline and in 16 subjects after isotonic saline, but this difference was not statistically significant. Intraclass correlation coefficients for sputum inflammatory cells obtained with the two methods were +0.642 for eosinophils, +0.644 for neutrophils, +0.544 for lymphocytes and +0.505 for macrophages. Hypertonic saline induced bronchoconstruction in a significantly greater number of subjects than isotonic saline. Also, hypertonic saline increased bronchial responsiveness to methacholine, while isotonic saline did not.We conclude that hypertonicity does not affect sputum cell composition, suggesting that inflammatory cells in hypertonic saline-induced sputum are probably preexisting and not acutely recruited in the airways by the hypertonic stimulus. However, the bronchoconstriction and the increase in bronchial hyper-responsiveness after hypertonic saline inhalation may imply the release of inflammatory mediators. This fact must be considered in the evaluation of soluble markers of inflammation in hypertonic saline-induced sputum.

The distribution function of pulmonary transit times (fPTT) defines contact time between blood and vascular bed, which affects gas exchange and endothelial metabolic functions. This study was undertaken to assess effects of abnormal pulmonary inflow (PPA) and outflow pressures (PLA) on fPTT. Three groups were studied: five patients with elevated PLA and passive pulmonary hypertension (LVD-Ab), eight with normal PLA (LVD-Nl), and six with pulmonary disease and various levels of PPA (PD). Empirical complex exponential functions were convoluted on right and left ventricular indicator-dilution curves to derive fPTT; mean transit time (Mo1), standard deviation (Sm2), and cube root of the third moment about Mo1 (Sm3) were calculated by standard equations. A single linear regression of Sm3 and Sm2 on Mo1 was observed for all patients, regardless of disease process. Inverse relations between Mo1, Sm2, and Sm3 and blood flow were highly significant, but dispersion volumes (DV = Mo1 x flow) were higher in patients with elevated PPA. Significant linear regressions of fPTT parameters on PPA, derived in LVD-Nl and LVD-Ab patients, failed to predict Mo1, Sm2, and Sm3 for the PD group, whereas linear regressions on PLA accurately predicted Mo1, Sm2, and Sm3 in the PD group. Relations between fPTT parameters and PLA were equally well fit by exponential equations in all 19 patients, consistent with an asymptotic pressure-volume relation of distensible vessels. Microvascular pressure (PMV), combining PPA and PLA, was not a better predictor of fPTT parameters in LVD-NL and LVD-Ab patients but provided a slightly closer estimate of relative dispersion and skewness in PD patients.(ABSTRACT TRUNCATED AT 250 WORDS)

In order to evaluate the pattern of airway response to a specific bronchial provocative test (sBPT) with an extract of Phleum pratensis standardized in biological units (BU), we studied 27 patients with seasonal asthma due to grass pollen by means of allergologic evaluations, methacholine inhalation test and sBPT, outside the pollen season in all patients and, in 10 of them, also during the pollen season. We used a DeVilbiss 646 nebulizer with a dosimeter, giving increasing doses (0.01-2.5 BU) of the allergen solution and we monitored FEV1 to assess early (EAR) and late (LAR) airway responses. Outside the pollen season sBPT elicited an isolated EAR in 16 and a dual asthmatic response (DAR) in 11 patients. We observed no significant difference between EAR and DAR patients as regards the provocative dose causing a 15% fall in FEV1 (PD15FEV1) methacholine, EAR (expressed by PD15FEV1 allergen) or allergologic data. There was a significant relationship between PD15FEV1 allergen and PD15FEV1 methacholine (r = 0.43, p less than 0.05). The reproducibility of sBPT was assessed in 11 patients outside the pollen season. The correlation coefficients between the two tests were: r = 0.91, p less than 0.001 for the total delivered dose of allergen during sBPT; r = 0.79, p less than 0.01 for PD15FEV1 allergen; r = 0.95, p less than 0.001 for the maximum percent fall in FEV1 during LAR. Ten patients repeated all tests during the grass pollen season. PD15FEV1 methacholine and baseline FEV1 decreased significantly during the pollen season, but PD15FEV1 allergen did not change significantly during the season.(ABSTRACT TRUNCATED AT 250 WORDS)

The title compound undergoes a first order phase transition at 370 K. The electrical and magnetic behaviours are consistent with a structural change from a highly dimerized structure at low temperature to a more regular one.