Salvinorin A reduces mechanical allodynia and spinal neuronal hyperexcitability induced by peripheral formalin injection

ABSTRACT: BACKGROUND: Salvinorin A (SA), the main active component of Salvia Divinorum, is a non-nitrogenous kappa opioid receptor (KOR) agonist. It has been shown to reduce acute pain and to exert potent antinflammatory effects. This study assesses the effects and the mode of action of SA on formalin-induced persistent pain in mice. Specifically, the SA effects on long-term behavioural dysfuctions and changes in neuronal activity occurring at spinal level, after single peripheral formalin injection, have been investigated. Moreover, the involvement of microglial and glial cells in formalin-induced chronic pain condition and in SA-mediated effects has been evaluated. RESULTS: Formalin induced a significant decrease of mechanical withdrawal threshold at the injected and contralateral paw as well as an increase in the duration and frequency, and a rapid decrease in the onset of evoked activity of the nociceptive neurons 7 days after formalin injection. SA daily treatment significantly reduced mechanical allodynia in KOR and cannabinoid receptor 1 (CB1R) sensitive manner. SA treatment also normalized the spinal evoked activity. SA significantly reduced the formalin-mediated microglia and astrocytes activation and modulated pro and anti-inflammatory mediators in the spinal cord. CONCLUSION: SA is effective in reducing formalin-induced mechanical allodynia and spinal neuronal hyperactivity. Our findings suggest that SA reduces glial activation and contributes in the establishment of dysfunctions associated with chronic pain with mechanisms involving KOR and CB1R. SA may provide a new lead compound for developing anti-allodynic agents via KOR and CB1R activation.     

Mutation of Glutamic Acid 103 of Toluene o-Xylene Monooxygenase as a Means To Control the Catabolic Efficiency of a Recombinant Upper Pathway for Degradation of Methylated Aromatic Compounds

Toluene o-xylene monooxygenase (ToMO) and phenol hydroxylase (PH) of Pseudomonas stutzeri OX1 act sequentially in a recombinant upper pathway for the degradation of aromatic hydrocarbons. The catalytic efficiency and regioselectivity of these enzymes optimize the degradation of growth substrates like toluene and o-xylene. For example, the sequential monooxygenation of o-xylene by ToMO and PH leads to almost exclusive production of 3,4-dimethylcatechol (3,4-DMC), the only isomer that can be further metabolized by the P. stutzeri meta pathway. We investigated the possibility of producing ToMO mutants with modified regioselectivity compared with the regioselectivity of the wild-type protein in order to alter the ability of the recombinant upper pathway to produce methylcatechol isomers from toluene and to produce 3,4-DMC from o-xylene. The combination of mutant (E103G)-ToMO and PH increased the production of 4-methylcatechol from toluene and increased the formation of 3,4-DMC from o-xylene. These data strongly support the idea that the products and efficiency of the metabolic pathway can be controlled not only through mutations that increase the catalytic efficiency of the enzymes involved but also through tuning the substrate specificity and regioselectivity of the enzymes. These findings are crucial for the development of future metabolic engineering strategies.     

Monodispersity of recombinant Cre recombinase correlates with its effectiveness in vivo

Background  

Cre recombinase is a common reagent used for the in vivo on/off switching of the expression of target genes flanked by loxP sites. In particular, recombinant TAT-Cre fusion constructs purified from bacteria have been used to promote the cell uptake of the enzyme. However, the recovery of active TAT-Cre remains a demanding process and its specific activity varies significantly among batches, making difficult data comparison.     

High cleavage specificity of a subtilisin-like protease from a hyperthermophilic archaeon under extreme conditions

The cleavage specificity of Pernisine, a subtilisin-like protease from the hyperthermophilic archaeon Aeropyrum pernix, was established by mass spectrometry, analysing the peptides generated by digestion of oxidised bovine insulin B chain. The specificity was explored by changing several factors such as substrate/enzyme ratio, temperature and reaction media. Using a S/E ratio of 1000 (w/w) and a temperature of 60 °C, five primary cleavage sites in the insulin B chain were detected suggesting a broad specificity of Pernisine, which is different from that found for other bacterial subtilisin-like proteases. When the S/E ratio and/or temperature were increased, a higher selectivity of Pernisine was observed with a unique cleavage site occurring between Leu15 and Tyr16. In addition, the influence on the enzymatic hydrolysis of different organic solvent concentrations was investigated. The results demonstrated that Pernisine could specifically digest the peptide substrate even in the presence of 80% acetonitrile solution or 30% dimethyl sulfoxyde. Thereby the cleavage specificity of Pernisine can be opportunely modulated by controlling the in vitro digestion conditions, suggesting that this enzyme could be an attractive candidate to use in a variety of biotechnological applications.     

Pharmacological studies on the sedative and hypnotic effect of Kava kava and Passiflora extracts combination

Kava kava extract, Passiflora extract and a combination of both extracts, administered to mice, caused a significant decrease of the amphetamine-induced hypermotility and significant prolongation of sleeping phase induced by subcutaneous injection of barbiturates. Due to a synergism of both extracts, simultaneously administered the pharmacologically registered effect in both in vivo experiments was found to be superior over the sum of the single separately administered extracts.     

Optimization of formulation variables of benzocaine liposomes using experimental design

This study aimed to optimize, by means of an experimental design multivariate strategy, a liposomal formulation for topical delivery of the local anaesthetic agent benzocaine. The formulation variables for the vesicle lipid phase uses potassium glycyrrhizinate (KG) as an alternative to cholesterol and the addition of a cationic (stearylamine) or anionic (dicethylphosphate) surfactant (qualitative factors); the percents of ethanol and the total volume of the hydration phase (quantitative factors) were the variables for the hydrophilic phase. The combined influence of these factors on the considered responses (encapsulation efficiency (EE%) and percent drug permeated at 180 min (P%)) was evaluated by means of a D-optimal design strategy. Graphic analysis of the effects indicated that maximization of the selected responses requested opposite levels of the considered factors: For example, KG and stearylamine were better for increasing EE%, and cholesterol and dicethylphosphate for increasing P%. In the second step, the Doehlert design, applied for the response-surface study of the quantitative factors, pointed out a negative interaction between percent ethanol and volume of the hydration phase and allowed prediction of the best formulation for maximizing drug permeation rate. Experimental P% data of the optimized formulation were inside the confidence interval (P < 0.05) calculated around the predicted value of the response. This proved the suitability of the proposed approach for optimizing the composition of liposomal formulations and predicting the effects of formulation variables on the considered experimental response. Moreover, the optimized formulation enabled a significant improvement (P < 0.05) of the drug anaesthetic effect with respect to the starting reference liposomal formulation, thus demonstrating its actually better therapeutic effectiveness.     

A novel keratinase from Clostridium sporogenes bv. pennavorans bv. nov., a thermotolerant organism isolated from solfataric muds

A bacterium which can grow on chicken feathers and which exhibits keratinolytic activity was isolated from solfataric muds. It was classified as belonging to the genus Clostridium and closely related to C. sporogenes. Based on its unique capability to degrade chicken feathers, it was designated as Clostridium sporogenes bv. pennavorans bv. nov. The keratinase purified from the culture supernatant is a monomer of 28.7kDa molecular mass. The enzyme is relatively thermostable and is active over a broad range of temperature and pH. Specific enzymatic assays demonstrate that keratinase can act on a large variety of soluble and insoluble protein substrates.     

Sphingolipid metabolic flow controls phosphoinositide turnover at the trans‐Golgi network

Sphingolipids are membrane lipids globally required for eukaryotic life. The sphingolipid content varies among endomembranes with pre‐ and post‐Golgi compartments being poor and rich in sphingolipids, respectively. Due to this different sphingolipid content, pre‐ and post‐Golgi membranes serve different cellular functions. The basis for maintaining distinct subcellular sphingolipid levels in the presence of membrane trafficking and metabolic fluxes is only partially understood. Here, we describe a homeostatic regulatory circuit that controls sphingolipid levels at the trans‐Golgi network (TGN). Specifically, we show that sphingomyelin production at the TGN triggers a signalling pathway leading to PtdIns(4)P dephosphorylation. Since PtdIns(4)P is required for cholesterol and sphingolipid transport to the trans‐Golgi network, PtdIns(4)P consumption interrupts this transport in response to excessive sphingomyelin production. Based on this evidence, we envisage a model where this homeostatic circuit maintains a constant lipid composition in the trans‐Golgi network and post‐Golgi compartments, thus counteracting fluctuations in the sphingolipid biosynthetic flow.     

Sulfonamide inhibition profile of the γ-carbonic anhydrase identified in the genome of the pathogenic bacterium Burkholderia pseudomallei the etiological agent responsible of melioidosis

A new γ-carbonic anhydrase (CA, EC 4.1.1.1) was cloned and characterized kinetically in the genome of the bacterial pathogen Burkholderia pseudomallei, the etiological agent of melioidosis, an endemic disease of tropical and sub-tropical regions of the world. The catalytic activity of this new enzyme, BpsCAγ, is significant with a k_cat of 5.3 × 10⁵ s^?1 and k_cat/K_m of 2.5 × 10⁷ M^?1 × s^?1 for the physiologic CO₂ hydration reaction. The inhibition constant value for this enzyme for 39 sulfonamide inhibitors was obtained. Acetazolamide, benzolamide and metanilamide were the most effective (K_Is of 149–653 nM) inhibitors of BpsCAγ activity, whereas other sulfonamides/sulfamates such as ethoxzolamide, topiramate, sulpiride, indisulam, sulthiame and saccharin were active in the micromolar range (K_Is of 1.27–9.56 μM). As Burkholderia pseudomallei is resistant to many classical antibiotics, identifying compounds that interfere with crucial enzymes in the B. pseudomallei life cycle may lead to antibiotics with novel mechanisms of action.