Treatment with afobazole at delayed time points following ischemic stroke improves long-term functional and histological outcomes.

There is currently a significant lack of therapeutic options for acute ischemic stroke, and no drug has been approved for treating patients at delayed time points (≥6h post-stroke). Afobazole, an anxiolytic currently used clinically in Russia, has been shown to reduce neuronal and glial cell injury in vitro following ischemia. Experiments using the permanent middle cerebral artery occlusion (MCAO) rat model were carried out to determine if afobazole can reduce ischemic stroke damage in vivo and expand the therapeutic window for stroke treatment. Post-stroke (24h) application of afobazole (0.3-3mg/kg) significantly decreased infarct volume at 96h post-surgery, as determined by Fluoro-Jade and NeuN staining of brain sections. Moreover, afobazole helped preserve both the levels and normal histological distribution of myelin basic protein, indicating a reduction in white matter injury. A time-dependence study showed that either pre-treatment or treatment started 6 to 48h post-stroke with the drug yields improved outcomes at 96h. The decrease in infarct volume produced by afobazole was blocked by the application of either a σ-1 (BD 1063, 30mg/kg) or a σ-2 (SM-21, 1mg/kg) antagonist, indicating that both receptor subtypes are involved in the effects of afobazole. Treatment with afobazole starting at 24h post-stroke resulted in enhanced survival one month following surgery. Behavioral testing of animals 28-32days post-surgery using the elevated body swing and forelimb grip-strength tests revealed that treatment with afobazole starting 24h post-stroke significantly reduces behavioral deficits caused by ischemic stroke. The increase in survival and improved functional outcomes are accompanied by a reduction in infarct volume, as determined by thionin staining of brain sections. Taken together, our data support the use of afobazole as a post-stroke pharmacological agent to expand the current therapeutic window.

Effect of interactions between amino acid residues 43 and 61 on thermal stability of bacterial formate dehydrogenases.

NAD+-dependent formate dehydrogenases (EC 1.2.1.2, FDH) of methylotrophic bacteria Pseudomonas sp. 101 (PseFDH) and Mycobacterium vaccae N10 (MycFDH) exhibit high homology. They differ in two amino acid residues only among a total of 400, i.e., Ile35 and Glu61 in MycFDH substitute for Thr35 and Lys61 as in PseFDH. However, the rate constant for MycFDH thermal inactivation in the temperature range of 54-65 degrees C is 4-6-times higher than the corresponding rate constant for the enzyme from Pseudomonas sp. 101. To clarify the role of these residues in FDH stability the dependence of the apparent rate constant for enzyme inactivation on phosphate concentration was studied. Kinetic and thermodynamic parameters for thermal inactivation were obtained for both recombinant wild-type and mutant forms, i.e., MycFDH Glu61Gln, Glu61Pro, Glu61Lys and PseFDH Lys61Arg. It has been shown that the lower stability of MycFDH compared to that of PseFDH is caused mainly by electrostatic repulsion between Asp43 and Glu61 residues. Replacement of Lys61 with an Arg residue in the PseFDH molecule does not result in an increase in stability.