Glutamate transporters in platelets: EAAT1 decrease in aging and in Alzheimer's disease.

Platelets release glutamate upon activation and are an important clearance system of the amino acid from blood, through high-affinity glutamate uptake, similar to that described in brain synaptosomes. Since platelet glutamate uptake is decreased in neurodegenerative disorders, we performed a morphological and molecular characterization of platelet glutamate transporters. The three major brain glutamate transporters EAAT1, EAAT2 and EAAT3 are expressed in platelets, with similar molecular weight, although at lower density than brain. A Na(+)-dependent-high-affinity glutamate uptake was competitively inhibited by known inhibitors but not by dihydrokainic acid, suggesting platelet EAAT2 does not play a major role in glutamate uptake at physiological conditions. We observed decreased glutamate uptake V(max), without modification of transporter affinity, in aging, which could be linked to the selective decrease of EAAT1 expression and mRNA. Moreover, in AD patients we found a further EAAT1 reduction compared to age-matched controls, which could explain the decrease of platelet uptake previously described. Platelet glutamate transporters may be used as peripheral markers to investigate the role of glutamate in patients with neuropsychiatric disorders.

3D-QSAR studies on 4-Hydroxyphenylpyruvate Dioxygenase inhibitors by comparative molecular field analysis (CoMFA)

A comparative molecular field analysis (CoMFA) of alkanoic acid 3-oxo-cyclohex-1-enyl ester and 2-acylcyclohexane-1,3-dione derivatives of 4-hydroxyphenylpyruvate dioxygenase inhibitors has been performed to determine the factors required for the activity of these compounds. The substrate's conformation abstracted from dynamic modeling of the enzyme-substrate complex was used to build the initial structures of the inhibitors. Satisfactory results were obtained after an all-space searching procedure, performing a leave-one out (LOO) cross-validation study with cross-validation q(2) and conventional r(2) values of 0.779 and 0.989, respectively. The results provide the tools for predicting the affinity of related compounds, and for guiding the design and synthesis of new HPPD ligands with predetermined affinities.

A new lead for nonpeptidic active-site-directed inhibitors of the severe acute respiratory syndrome coronavirus main protease discovered by a combination of screening and docking methods.

The coronavirus main protease, Mpro, is considered to be a major target for drugs suitable for combating coronavirus infections including severe acute respiratory syndrome (SARS). An HPLC-based screening of electrophilic compounds that was performed to identify potential Mpro inhibitors revealed etacrynic acid tert-butylamide (6a) as an effective nonpeptidic inhibitor. Docking studies suggested a binding mode in which the phenyl ring acts as a spacer bridging the inhibitor's activated double bond and its hydrophobic tert-butyl moiety. The latter is supposed to fit into the S4 pocket of the target protease. Furthermore, these studies revealed etacrynic acid amide (6b) as a promising lead for nonpeptidic active-site-directed Mpro inhibitors. In a fluorimetric enzyme assay using a novel fluorescence resonance energy transfer (FRET) pair labeled substrate, compound 6b showed a Ki value of 35.3 M. Since the novel lead compound does not target the S1', S1, and S2 subsites of the enzyme's substrate-binding pockets, there is room for improvement that underlines the lead character of compound 6b.

Functional and Physiological Determinants of Perceived Disability in Individuals Diagnosed with Osteoarthritis of the Hip

Objectives: The main objective of this pilot study was to investigate which standardized functional and physiological test best predicted perceived disability in a single group of 21 individuals diagnosed with osteoarthritis of the hip. Design: Men and women between 60 and 70 years old with osteoarthritis of the hip were selected. If participants passed study criteria, the Western Ontario McMaster University questionnaire (WOMAC), 6 Minute Walk Test (6MWT) and Timed up and Go (TUG), strength testing and aerobic testing were obtained in one single assessment. Results: Regression analysis revealed that wait time, hip abduction strength of the affected side, Aerobic Capacity (VO2 Peak), hip Extension Peak Torque, hip Flexion Peak Torque, TUG and 6MWT were significantly correlated with the WOMAC. Yet, the 6MWT had the highest significant correlation (r = -0.86, p ≤ 0.0001); R2 = 0.75 or 75% with the WOMAC total scores, (r = -0.82, p ≤ 0.0001); R2 = 0.67 or 67% with the WOMAC function and (r = -0.60, p = .002); R2 = 0.36 or 36% with the WOMAC stiffness. While the VO2 Peak revealed the highest significant correlation (r = 0.76, p ≤ .0001); R2 = 0.57 or 57% with the WOMAC pain. Conclusions: The 6MWT and the VO2 Peak seem to be essential functional and physiological assessment tools to determine perceived disability in individuals with hip OA. The perceived disability may provide new or comprehensive knowledge of the disability problems experienced by individuals with osteoarthritis of the hip, and the association of patient perception with objective measures of functional and physiological capacity might strengthen the clinical value of this knowledge.