The carbonation kinetics of calcium hydroxide nanoparticles: A Boundary Nucleation and Growth description

HYPOTHESIS

The reaction of Ca(OH)₂ with CO₂ to form CaCO₃ (carbonation process) is of high interest for construction materials, environmental applications and art preservation. Here, the "Boundary Nucleation and Growth" model (BNGM) was adopted for the first time to consider the effect of the surface area of Ca(OH)₂ nanoparticles on the carbonation kinetics.

EXPERIMENTS

The carbonation of commercial and laboratory-prepared particles' dispersions was monitored by Fourier Transform Infrared Spectroscopy, and the BNGM was used to analyze the data. The contributions of nucleation and growth of CaCO₃ were evaluated separately.

FINDINGS

During carbonation the boundary regions of the Ca(OH)₂ particles are densely populated with CaCO₃ nuclei, and transform early with subsequent thickening of slab-like regions centered on the original boundaries. A BNGM limiting case equation was thus used to fit the kinetics, where the transformation rate decreases exponentially with time. The carbonation rate constants, activation energies, and linear growth rate were calculated. Particles with larger size and lower surface area show a decrease of the rate at which the non-nucleated grains between the boundaries transform, and an increase of the ending time of Ca(OH)₂ transformation. The effect of temperature on the carbonation kinetics and on the CaCO₃ polymorphs formation was evaluated.

Thymosin alpha-1 with peginterferon alfa-2a/ribavirin for chronic hepatitis C not responsive to IFN/ribavirin: an adjuvant role?

This study was conducted to determine whether the adding thymosin alpha-1 to standard of care for re-treatment of nonresponding hepatitis C infections can improve sustained viral response (SVR) rates. Patients (n = 552) with hepatitis C infections not responding to the combination of Peginterferon alfa-2a or 2b with ribavirin (RBV)were randomized to receive peginterferon alfa-2a 180 mg/week with RBV 800-1200 mg/daily plus either thymosin alpha-1 1.6 mg SC twice weekly (n = 275) or placebo (n = 277) for 48 weeks. Eighty-eight per cent of patients had HCV genotype 1, 6.6% type 4, 2.2% type 2 and 3.6% type 3. SVR rates in the intention to treat population were similar between thymosin alpha-1 and placebo (12.7%vs 10.5%; P = 0.407). Among patients who completed all 48 weeks of therapy, the SVR rate was significantly higher in the thymosin alpha-1 group at 41.0% (34/83) compared with 26.3% (26/99) in the placebo group (P = 0.048). No significant difference was observed between treatment groups in the incidence of adverse events. The addition of thymosin alpha-1 to the standard of care did not increase the on-treatment HCV viral response. Thymosin alpha-1 seems to play no role in the primary therapy of the disease. This study raises the hypothesis that thymosin alpha-1 may have a secondary therapeutic role as an adjuvant in the prevention of relapses in patients achieving a virologic response during therapy.

Randomised clinical trial: the efficacy and safety of propionyl-L-carnitine therapy in patients with ulcerative colitis receiving stable oral treatment

BACKGROUND

Ulcerative colitis (UC) is characterised by impaired fatty-acid oxidation; l-carnitine has a key role in fatty-acid metabolism and short-chain fatty acids such as butyrate and propionate are important energy source for intestinal epithelial cells.

AIM

To evaluate efficacy and safety of colon-release propionyl-L-carnitine (PLC) in patients with mild-to-moderate UC receiving stable oral aminosalicylate or thiopurine therapy.

METHODS

In a multicentre, phase II, double-blind, parallel-group trial, patients were randomised to receive PLC 1 g/day, PLC 2 g/day or placebo. Main inclusion criteria were as follows: age 18-75; disease activity index (DAI) score 3-10 inclusive, be under oral stable treatment with aminosalicylate or thiopurine. The primary endpoint was clinical/endoscopic response, defined as a decrease in DAI score ≥ 3 points or remission, defined as a DAI score ≤ 2 with no individual sub-score > 1.

RESULTS

Of 121 patients who were randomised, 57 of 79 (72%) patients receiving PLC (combined 1 g and 2 g cohort) had a clinical/endoscopic response vs. 20 of 40 (50%) receiving placebo (P = 0.02). Specifically, in PLC 1 g/day group, 30 of 40 (75%) patients had clinical/endoscopic response (P = 0.02 vs. placebo) and 27 of 39 (69%) in the PLC 2 g/day group (P = 0.08 vs. placebo). Rates of remission were 22/40 (55%), 19/39 (49%), 14/40 (35%) in the PLC 1 g, PLC 2 g, and placebo groups, respectively. PLC had a similar safety profile to placebo; the most common adverse events were gastrointestinal.

CONCLUSION

Propionyl-L-carnitine 1 g/day should be investigated further as a co-treatment for mild-to-moderate ulcerative colitis (NCT-01026857).

Utility of thymosin alpha-1 (Zadaxin) as a co-adjuvant in influenza vaccines: a review

Influenza constitutes a serious problem for healthcare and social services worldwide, owing to its pattern and the severity of its complications in some categories of subjects at risk, such as the elderly and immunocompromised individuals. The only really effective means of combating influenza is vaccination. The elderly and immunocompromised subjects are refractory or low responders to vaccination. The need for ever more immunogenic and efficacious influenza vaccines, especially for subjects at risk, has prompted the development of adjuvated vaccines. With a view to enhancing the immune response in the elderly and in subjects at risk, the possibility of co-administering immunostimulants as Thymosin alpha-1 (Talpha1) with influenza vaccines has been investigated. Talpha1 is a biologically active peptide made up of 28 amino acids that can enhance T-cells, dendritic cell and antibody responses, modulate cytokines and chemokines production. Several studies were conducted and showed that Talpha1 ameliorate the performanc of influenza vaccination in elderly and subjects at risk. Although further studies on co-adjuvants are necessary, the future prospects of producing ever more efficacious influenza vaccines appear very promising.

A large first-line, randomized, dose-finding, phase II study on thymosin-alpha 1 (T-alpha 1) plus dacarbazine (DTIC) with or without interferon-alpha (IFN-alpha) compared to DTIC plus IFN-alpha in stage IV melanoma. Tumor response and survival results

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Background: Thymosin alpha 1 is an immunomodulatory compound that promotes T cell maturation and upregulates T cell response. Ta1 showed clinical potential benefit in a previous pilot study in melanoma patients. Methods: Phase II, randomized, stratified, open-study testing different doses of Ta1 in association with DTIC and IFNa, as first-line therapy in stage IV melanoma patients (AJCC 2001) without brain metastases. The primary endpoint is tumor response and secondary overall survival. Four arms were initially planned: DTIC + IFNa + 1.6 or 3.2 mg Ta1, DTIC + 3.2 mg Ta1, and DTIC + IFNa (control group). A dose-response effect in a preliminary analysis on 142 patients led to the addition of a fifth arm with DTIC + IFNa + 6.4 mg Ta1. Ninety-five patients were allocated to each arm to test the hypothesis that P0 = 0.05 vs the alternative hypothesis that P1 = 0.15 (alpha = 5%, within-group statistical analysis, power = 95%). The five groups were analyzed independently one from the other, nine responses representing the minimal threshold for rejecting the null hypothesis Patients received DTIC (800 mg/m2) iv on day 1, Ta1 (1.6, 3.2 or 6.4 mg) sc on days 8–11 and 15–18, and IFNa (3 MIU) sc on days 11 and 18 during 28d cycles. Tumor response was evaluated every two cycles according to RECIST criteria, utilizing a central review. Results: Data of 483 pts (62% M1c; 25% M1b; 13% M1a) from 64 European sites are given in the table . Thirteen and 10 confirmed responses were observed for the DTIC+ 3.2 mg Ta1 and DTIC+ IFNa + 3.2 mg Ta1 arms (vs 5 in the control group) thus rejecting the null hypothesis that P0 = 0.05. No additional toxicity with the addition of Ta1 was observed. Conclusions: These results suggest a potential survival advantage with the addition of Ta1 to ‘standard‘ treatment of stage IV melanoma patients. The role of Interferon alpha in this therapeutic association is debatable.

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Effects of zileuton, a new 5-lipoxygenase inhibitor, in experimentally induced colitis in rats

The efficacy of zileuton, a new 5-lipoxygenase inhibitor, was investigated in comparison with sulphasalazine in an experimental model of rat colitis. Under light anaesthesia with ether, male rats were subjected to intracolonic administration of trinitrobenzene sulfonic acid (TNB) in 50% ethanol and were then sacrificed 2, 4 and 7 days after colitis induction. Untreated rats exhibited elevated colonic levels of leukotriene B4 (LTB4) and 6-keto-PGF1 alpha, and an increase in colonic myeloperoxidase (MPO) activity (investigated as an index of leukocyte adhesion and accumulation). Moreover, ulceration and inflammation of the distal colon with formation of granuloma and pathologic connections were observed. Treated rats received zileuton or sulphasalazine (50 mg/kg per os twice a day) 24 h before the induction of colitis until they were sacrificed. Treatment with the specific 5-lipoxygenase inhibitor, zileuton, resulted in significant reductions of colonic leukotriene B4 and 6-keto-PGF1 alpha synthesis, macroscopic and histological colonic damage and colonic inflammation as assessed by the measurement of MPO activity. In contrast, sulphasalazine had a lower effect than zileuton on LTB4 and MPO levels (p < 0.05), while it was able to reduce colonic damage and 6-keto-PGF1 alpha levels as well as zileuton. This study shows, therefore, that zileuton is effective in attenuating the lesions in an experimental model of colitis. Furthermore, the results are consistent with the hypothesis that leukotrienes play an important role in the pathogenesis of intestinal bowel diseases (IBD).