Host-guest chemistry of a bis-calix[4]pyrrole derivative containing a trans/cis-switchable azobenzene unit with several aliphatic bis-carboxylates.

The azobenzene unit used as a photochemically and thermally switchable linker in the assembly of a bis-calix[4]pyrrole receptor provides a means to modulate the binding of bis-carboxylates of significant biological importance in cancer research. Conversely, the complexation of different bis-anionic guests has significant kinetic effects on both the photochemical and thermal trans/cis isomerization of the azobenzene unit.

Auxin induces cell proliferation in an experimental model of mammalian renal tubular epithelial cells.

Indole-3-acetic acid is the main auxin produced by plants and plays a key role in the plant growth and development. This hormone is also present in humans where it is considered as a uremic toxin deriving from tryptophan metabolism. However, beyond this peculiar aspect, the involvement of auxin in human pathophysiology has not been further investigated. Since it is a growth hormone, we evaluated its proliferative properties in an in vitro model of mammalian renal tubular epithelial cells. We employed an experimental model of renal tubular epithelial cells belonging to the LLC-PK1 cell line that is derived from the kidney of healthy male pig. Growth effects of auxin against LLC-PK1 cell lines were determined by a rapid colorimetric assay. Increasing concentrations of auxin (to give a final concentration from 1 to 1000 ng/mL) were added and microplates were incubated for 72 h. Each auxin concentration was assayed in four wells and repeated four times. Cell proliferation significantly increased, compared to control cells, 72 h after addition of auxin to cultured LLC-PK1 cells. Statistically significant values were observed when 100 ng/mL (p < 0.01) and 1000 ng/mL (p < 0.05) were used. In conclusion, auxin influences cell growth not only in plants, where its role is well documented, but also in mammalian cell lines. This observation opens new scenarios in the field of tissue regeneration and may stimulate a novel line of research aiming at investigating whether this hormone really influences human physiology and pathophysiology and in particular, kidney regeneration.

Sevalamer Hydrochloride, Sevelamer Carbonate and Lanthanum Carbonate: In Vitro and In Vivo Effects on Gastric Environment.

Hyperphosphatemia is common in patients with chronic renal failure. Phosphate binders are associated with gastric intolerance, representing the main reason of drug discontinuation. The aim of this study was to compare the effects in vitro and in vivo of sevelamer hydrochloride (SH), sevelamer carbonate (SC) and lanthanum carbonate (LC) on gastric microenvironment. We have also evaluated the efficacy and tolerability of these drugs in hemodialysis (HD) patients. In vitro analysis: Dissolution time, ability to uptake phosphorus, changes in pH starting from gastric milieu and the amount of carbon dioxide (CO(2)) produced were the variables analyzed. In vivo analysis: 24-h esophago-gastric pH measurement was evaluated in 24 HD patients treated with phosphate binders and proton pump inhibitor (PPI). In vitro: LC dissolved over a longer time compared with SC (58 ± 2.4 vs. 12 ± 0.6 min; P < 0.001) and SH (58 ± 2.4 vs. 10.3 ± 0.8 min; P < 0.001), determining the most alkaline pH. SC had the highest chelation power, binding 4.00 × 10(-9) mol/L of phosphoric acid. CO2 volume released was increased in LC solution (53.2 ± 7.8) compared to SC (33.9 ± 6.2; P < 0.001) and SH (2.3 ± 1.8; P < 0.001). In vivo: gastric pH increased after administration of phosphate binder. The most alkaline pH was recorded in patients treated with SC. The alkalinization of the gastric environment was not prevented by PPI therapy. 424 episodes of esophageal reflux were registered, 74% of them were alkaline. The LC group was characterized by the highest number of episodes. Sevelamer carbonate had a greater capacity and rapidity to chelate phosphorus, with a mild tolerability, due to its low CO(2) production. Sevelamer HCl was the most tolerated chelator because it did not produce CO(2), while lanthanum carbonate was the least soluble.

Correlation between quality of life assessment and a personality neurobiologic model in dialyzed patients.

The Short Form 36 Health Survey (SF-36) is a self-administered scoring system that has been widely used and validated as a quality of life (QOL) assessment tool. In our study, a cluster analysis of SF-36 scores was performed in 50 healthy volunteers (controls) and 50 neurobiologically asymptomatic patients on maintenance hemodialysis (MHD). Firstly, we assayed the tendency to form clusters from each of the investigated dimensions. Statistic analysis was performed using the Student's t-test for independent measurements and multiple regression analysis. Secondly, we attempted to evaluate if the MHD to apply to both groups a general psychobiological personality model developed by Cloninger in 1987. Cloninger describes three independent personality dimensions: novelty seeking (NS), harm avoidance (HA)and reward dependence (RD). Each personality dimension would be the expression of hereditary variations integrating the three main brain systems, respectively: dopaminergic, serotoninergic and noradrenergic. Finally, we then aimed to investigate possible interferences among the seric concentrations of the neuromodulators and SF-36 scores, in the attempt to identify, using a simple approach, the complex personality structure of MHD patients. QOL self-assessment and seric neuromodulators were measured in both groups, choosing an interdialytic day for MHD patients. We found that MHD patients perceived a significant worsening in their QOL in all investigated dimensions with respect to the controls. In addition, they showed significantly lower dopamine and serotonine concentrations and significantly higher noradrenaline concentrations. Therefore, our study, confirmed data reported previously in the literature, that cluster analysis of SF-36 scores provides different results in the MHD population in comparison to normal subjects. In fact, comparing the hierarchical trees of both groups, it appeared evident that in MHD patients, cluster dimensions were greater than in the controls. In cluster compositions showed differences between the two groups. In fact, in MHD patients there were only a few of the clusters that were observed in the controls (mental health and social functioning, vitality and general health), while role-physical and role-emotional dimensions aligned outside the hierarchical tree, with a considerable linkage distance. In our opinion, it is fascinating that the three Cloninger neuromodulators could suggest that HD patient personalities are potentially cyclothymiac, altering the disposition of the two role functions inside the hierarchical tree.

Variable-ionic strength kinetic experiments in drug stability studies.

The dependence of the pseudo-first-order rate constant on the ionic strength for the alkaline hydrolysis of indomethacin has been obtained, for the first time, in a single kinetic experiment carried out by varying with time the salt concentration inside the reaction vessel. The kinetic profile obtained was processed using as a mathematical model the variable-parameter kinetic equation containing the Bronsted-Bjerrum equation as the dependence function. The results are in good agreement with those obtained by the traditional method but the experimental time is reduced to about one-tenth.

Fast drug stability determination by LC variable-parameter kinetic experiments.

Variable-parameter kinetic experiments were carried out using HPLC as analytical instrument. The hydrolysis of aspirin was followed both at variable-temperature and at variable-pH conditions. The peak areas relative to salicylic acid were processed by direct fit to a mathematical model and/or by differential method obtaining, by single experiments, the values of the apparent rate constant in the whole range of temperature and pH studied. The results, although the discontinuity of this kind of analysis, are in agreement with those obtained by constant-parameter kinetics but saving experimental time.

Temperature-rate profiles by polarimetric variable-temperature kinetic experiments to study racemization reactions.

The racemization of (-)-adrenaline was followed by polarimetric variable-temperature kinetic experiments obtaining activation parameters and k(obs)(T) profile in one tenth of the time usually spent for traditional kinetic runs. A polarimeter connected to a computer for the acquisition and processing of the analytical data was used. The kinetic profiles were processed by both an integral method and a differential method. The results are in good agreement with each other and with those obtained by constant-temperature kinetics.

The discrimination potential of ultraviolet-visible spectrophotometry, thin layer chromatography, and Fourier transform infrared spectroscopy for the forensic analysis of black and blue ballpoint inks.

The knowledge of the discriminating power of analytical techniques used for the differentiation of writing inks can be useful when interpreting results. Ultraviolet-visible (UV-VIS) spectrophotometry, thin layer chromatography (TLC), and diffuse reflectance Fourier transform infrared spectroscopy (FT-IR) were used to examine a population of 21 black and 12 blue ballpoint writing inks. Based on corroborative results of these methods, the discrimination power for UV-VIS, TLC, and FT-IR was determined to be 100% and 98% for the black and blue inks, respectively. Generally, TLC and UV-VIS can be used to differentiate the colorant components (i.e., dyes and some pigments) found in inks. As FT-IR can be utilized to identify some of the noncolorant components, it was determined to be an excellent complementary technique that can be implemented into an analytical scheme for ink analysis.