New insights on the mechanism of oxidation of D-galacturonic acid by hypervalent chromium.

The pollutant Cr(VI) is known to be very carcinogenic. In conditions of excess of Cr(VI), oxidation of D-galacturonic acid (Galur), the major metabolite of pectin, yields d-galactaric acid (Galar) and Cr(III). The redox reaction takes place through a multistep mechanism involving formation of intermediate Cr(II/IV) and Cr(V) species. The mechanism combines one- and two-electron pathways for the reduction of Cr(IV) by the organic substrate: Cr(VI)→ Cr(IV)→ Cr(II) and Cr(VI)→ Cr(IV)→ Cr(III). This is supported by the observation of the optical absorption spectra of Cr(VI) esters, free radicals, CrO(2)(2+) (superoxoCr(III) ion) and oxo-Cr(V) complexes. Cr(IV) cannot be directly detected; however, formation of CrO(2)(2+) provides indirect evidence for the intermediacy of Cr(II/IV). Cr(IV) reacts with Galur much faster than Cr(V) and Cr(VI) do. The analysis of the reaction kinetics via optical absorption spectroscopy shows that the Cr(IV)-Galur reaction rate inversely depends on [H(+)]. Nevertheless, high [H(+)] still does not facilitate accumulation of Cr(IV) in the Cr(VI)-Galur mixture. Cr(VI) and the intermediate Cr(V) react with Galur at comparable rates; therefore the build-up and decay of Cr(V) accompany the decay of Cr(VI). The complete rate laws for the Cr(VI), Cr(V) and Cr(IV)-Galur redox reaction are here derived in detail. Furthermore, the nature of the five-co-ordinated oxo-Cr(V) bischelate complexes formed in Cr(VI)-Galur mixtures at pH 1-5 is investigated using continuous-wave and pulsed electron paramagnetic resonance (EPR) and density functional theory (DFT).

Clinical and inflammatory features of occupational asthma caused by persulphate salts in comparison with asthma associated with occupational rhinitis.

BACKGROUND: The relationships between asthma and rhinitis are still a crucial point in respiratory allergy and have scarcely been analysed in occupational setting. We aimed to compare the clinical and inflammatory features of subjects with occupational asthma only (OA) to subjects with OA associated to occupational rhinitis (OAR) caused by persulphate salts. METHODS: The clinical charts of 26 subjects diagnosed in our Unit as respiratory allergy caused by ammonium persulphate (AP), confirmed by specific inhalation challenge (SIC), were reviewed. Twenty-two out of twenty-six patients underwent pre-SIC-induced sputum challenge test (IS) and 24/26 underwent nasal secretion collection and processing. RESULTS: Twelve out of twenty-six patients received a diagnosis of OA-only and 14/26 of OAR. Duration of exposure before diagnosis, latency period between the beginning of exposure and asthma symptom onset, basal FEV(1), airway reactivity to methacholine and asthma severity did not differ in the two groups. Eosinophilic inflammation of upper and lower airways characterized both groups. Eosinophil percentage in IS tended to be higher in OAR [11.9 (5.575-13.925)%] than in OA-only [2.95 (0.225-12.5)%] (P = 0.31). Eosinophilia in nasal secretions was present both in subjects with OAR [55 (46-71)%] and in subjects with OA-only [38 (15-73.5)%], without any significant difference. DISCUSSION: Our results indicate that OA because of ammonium persulphate coexists with occupational rhinitis in half of the patients. Unexpectedly, rhinitis did not seem to have an impact on the natural history of asthma. The finding of nasal inflammation in subjects with OA-only without clinical manifestations of rhinitis supports the united airway disease concept in occupational respiratory allergy as a result of persulphates.

[Immunotherapy with low-dose subcutaneous interleukin-2 in metastatic renal carcinoma]. / Immunoterapia con basse dosi di interleuchina-2 per via sottocutanea nel carcinoma renale metastatico.

The intravenous injection of interleukin-2 (IL-2) has appeared to induce tumor regression in metastatic renal cell carcinoma (RCC). IL-2 given subcutaneously has also appeared to be effective when it is administered in association with interferon-alpha (INF), but with a lower toxicity in comparison to the intravenous route of administration. The present study was carried out to evaluate the efficacy of a subcutaneous immunotherapy with IL-2 alone in metastatic RCC. The study included 30 consecutive patients affected by metastatic RCC, 14 of whom had been pretreated with INF plus vinblastine, while the other 16 patients received IL-2 as a first line therapy of their metastatic disease. IL-2 was given subcutaneously at a dose of 3 million IU twice/day for 5 days/week for 6 consecutive weeks, corresponding to one cycle of immunotherapy. No complete response was obtained. A partial response (PR) was achieved in 10/30 (33%) patients (median duration: 7 months, range 5-25), without any significant difference between patients pretreated with IFN and nonpretreated patients (4/14 vs 6/16). Response rate was significantly higher in nephrectomized patients than in those who did not undergo nephrectomy (10/25 vs 0/5; P < 0.01). Moreover, response rate was significantly higher in patients with performance status (PS) greater than 40% than in those with PS lower than 40% (10/23 vs 0/7; P < 0.01). A stable disease (SD) was obtained in 12/30 (40%) patients (median duration 5 months, range 3-13), while the remaining 8/30 (27%) progressed. The increase in lymphocyte and eosinophil mean number was significantly higher in patients with PR or SD than in the progressed ones.(ABSTRACT TRUNCATED AT 250 WORDS)