New methods for estimation of surface tension and viscosity of pure component organic chemicals are presented. The surface tension is estimated at 298 K while the viscosity is estimated at 300 K. For both properties, the combined group contribution-atom connectivity index approach has been employed, where the same set of experimental data is used for a group contribution (GC)-based model and an atom connectivity index (CI)-based method and then the model parameters for the atom-CI method are used to predict the missing parameters of the GC method. In this way, using the same set of experimental data, the application range of the GC method is enlarged through the combined GC-CI method. Group contributions for surface tension (98, 39, and 8 for first, second, and third order groups, respectively) and for viscosity (108, 39, and 12 for first, second, and third order groups, respectively) have been regressed using two collected sets of experimental data consisting of 420 compounds for surface tension and 445 for viscosity, including C, H, N, O, F, Cl, Br, and S atoms, some of which are complex polycyclic compounds. The new methods have been compared with other GC methods, and their use in mixture property models have also been highlighted through illustrative examples.
Metallothioneins (MTs) are low-molecular weight cysteine- and metal-rich proteins with unquestionable metal binding capacity, antioxidant and anti-inflammatory properties, and a clear involvement in diverse physiological actions as inhibition of proapoptotic mechanisms, enhancement of cell survival, and tissue regeneration. Concurrent with this wide array of functions, MT-1/2 have been implicated in neuroprotection and neuroregeneration. The zinc binding capacity and antioxidant properties of MTs may account for most of their physiological features in the brain. However, some receptor-mediated actions of MT-1/2 have also been reported recently, a subject to be fully elucidated. This review analyses and updates the current knowledge on the actions of MTs related to neuroprotection and neuroregeneration in an effort to distinguish receptor-mediated actions of MTs from those arising from its zinc binding capacity and its antioxidant properties.
Transthyretin (TTR) is a carrier for thyroid hormones and retinol binding protein. Several mutated forms of TTR cause familial amyloidotic polyneuropathy, an inheritable lethal disease. On the other hand, wild-type TTR has a protective role against Alzheimer's disease. Despite its overall importance in normal animal physiology and in disease, few studies have focused on its regulation. An in silico analysis of the rat TTR gene revealed a glucocorticoid responsive element in the 3' region of the first intron. Thus, we hypothesised that TTR could be regulated by glucocorticoid hormones and investigated the regulation of TTR expression in response to hydrocortisone in a rat choroid plexus cell line (RCP) and in primary cultures of choroid plexus epithelial cells (CPEC). In addition, the effect of psychosocial stress on TTR expression was analysed in rat liver, choroid plexus (CP) and cerebrospinal fluid (CSF). In RCP and CPEC cultures hydrocortisone upregulated TTR expression, an effect suppressed by glucocorticoid receptor and mineralocorticoid receptor antagonists. Moreover, induction of psychosocial stress increased TTR expression in liver, CP and CSF of animals subjected to acute and chronic stress conditions. Overall, we conclude that stress upregulates TTR expression in CP.
Transthyretin (TTR), an amyloid-beta (Abeta) scavenger protein, and metallothioneins 2 and 3 (MT2 and MT3), low molecular weight metal-binding proteins, have recognized impacts in Abeta metabolism. Because TTR binds MT2, an ubiquitous isoform of the MTs, we investigated whether it also interacts with MT3, an isoform of the MTs predominantly expressed in the brain, and studied the role of MT2 and MT3 in human TTR-Abeta binding. The TTR-MT3 interaction was characterized by yeast two-hybrid assays, saturation-binding assays, co-immunolocalization and co-immunoprecipitation. The effect of MT2 and MT3 on TTR-Abeta binding was assessed by competition-binding assays. The results obtained clearly demonstrate that TTR interacts with MT3 with a K(d) of 373.7 +/- 60.2 nm. Competition-binding assays demonstrated that MT2 diminishes TTR-Abeta binding, whereas MT3 has the opposite effect. In addition to identifying a novel ligand for TTR that improves human TTR-Abeta binding, the present study highlights the need to clarify whether the effects of MT2 and MT3 in human TTR-Abeta binding observed in vitro have a relevant impact on Abeta deposition in animal models of Alzheimer's disease.
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