Can the Organization of a Binary Mix Be Predicted from the Surface Energy,Cohesion Parameter and Particle Size of Its Components?

Purpose. The aim of this study was to relate the organization of several binary mixes with three physical parameters (surface energy, cohesion parameter, and particle size) of various materials blended with each other. Methods. Four pharmaceutical compounds were selected for their surface energies and cohesion parameters. Binary mixes were prepared from different sieved fractions. The frequency and nature of the interactions between the particles were observed by scanning electron microscopy. Results. As expected, interactions were determined by both the energetics and the relative particle size of the two compounds blended, the latter determining the mode of interaction. However, particle size was not the only factor influencing the organization of the blends as, sometimes, small particles of a material would not adhere to the coarser particles of the other. Thus, a surface energy derived parameter ^B/A – ^A/B appears to be a valuable estimating tool of the potentiality of interaction between the particles blended. No correlation between the cohesion parameters of the compounds and the organization of the resulting blends could be found. Conclusions. Surface energy and particle size play a major role in the organization of a binary blend. However, they cannot explain separately the interactions observed between the fractions blended as reliable predictions require the use of both characteristics.     

Can the Cellular Internalization of Cargo Proteins Be Enhanced by Fusing a Tat Peptide in the Center of Proteins? A Fluorescence Study

The aim of this study was to investigate whether the cellular uptake of cargo proteins can be enhanced by fusing a Tat peptide in the center of proteins; glutathione-S-transferase (GST)-Tat-green fluorescent protein (GFP) and GST-GFP-Tat proteins were first constructed and expressed. The cellular internalization of both proteins was then evaluated and compared in HeLa cells using fluorescent microscopy and flow cytometry, as well as the transdermal delivery in human skin using confocal microscopy. Results from in vitro cell experiments showed that GST-Tat-GFP protein efficiently internalized into HeLa cells when a Tat peptide was fused in the center of proteins, whereas its efficiency is lower than that of GST-GFP-Tat protein with a Tat peptide terminal fused. Ex vivo transdermal delivery data also demonstrated that the lower efficiency of GST-Tat-GFP penetrating through human stratum corneum layer when compared with GST-GFP-Tat. Furthermore, both GST-GFP-Tat and GST-Tat-GFP presented a various degree of a mixture of cytoplasmic diffuse staining and punctate surface staining, and the pattern of distribution varied considerably in HeLa cell experiments depending on the concentration of protein used. Therefore, an improved mechanism for Tat-conjugated proteins was proposed, in which Tat-conjugated proteins were first associated with cell membrane, then accumulated on the cell surface, and finally internalized into cells by pore formation mechanism.     

The Toxicological Effects Following the Ingestion of Chinook Salmon from the Great Lakes by Sprague–Dawley Rats during a Two-Generation Feeding-Reproduction Study

A two-generation reproduction–feeding study was undertaken with Sprague–Dawley rats to ascertain the effects of ingesting chinook salmon fillets caught in the Credit River, which empties into Lake Ontario (LO), or in the Owen Sound region of Lake Huron (LH). Rats (30/sex/group) were randomly assigned to groups whose dietary protein consisted of casein and/or lyophilized salmon [Group 1: 20% casein (controls); Group 2: 15% casein + 5% LO salmon (LO-5%); Group 3: 20% LO salmon (LO-20%); Group 4: 15% casein + 5% LH salmon (LH-5%); Group 5: 20% LH salmon (LH-20%)]. After 70 days on test, the males and females were mated on a 1:1 basis within diet groups. Approximately 70 days postweaning, one F₁male and one F₁female from 24 litters were mated within diet groups, avoiding sibling matings. At weaning, the F₀and F₁adults and the F₁and F₂neonates not randomly selected for further testing were necropsied. Evaluated parameters included growth, feed consumption, organ weights, reproduction indices, serum chemistry, hematology, and coagulation times. The only statistically significant effects which were present in both generations were increased relative liver and kidney weights of both sexes in the LO-20% and LH-20% groups; the LH-20% females had lower alanine transaminase activity than the controls; the controls had lower creatinine levels than the fish groups and the LO-20% females; the LH-20% and LO-20% males had a lower blood urea nitrogen than the controls; and the LH-20% females had a heavier terminal body weight than the controls and a lower number of red blood cells, hematocrit, hemoglobin values, and mean platelet volume. There was a tendency for the fish-fed groups to grow faster, eat more feed, and have larger litters with heavier pups. Overall, there was little to suggest that the myriad of contaminants in chinook salmon from the Great Lakes presented an appreciable toxicological risk to Sprague–Dawley growth and reproduction.     

Characterization of a Stable 2,2′-Azobis(2-Methylpropanenitrile) Degradant and Its Use to Monitor the Oxidative Environment During Forced Degradation Studies by Liquid Chromatography/Mass Spectrometry

Azo compounds are commonly used to study radical-mediated degradation of pharmaceutical compounds. The favorable chemical and physical properties of 2,2′-azobis(2-methylpropanenitrile) (AIBN) have made it one of the most widely used compound for these type of studies. This article describes the characterization of a stable product, N-(1-cyano-1-methylethyl)-2-methylpropanamide, formed during the decomposition of AIBN. This product is easily detected by liquid chromatography/mass spectrometry and can serve as a marker to confirm the AIBN is working as intended and to monitor the kinetic formation of free radical species.     

Blockade of Tau Hyperphosphorylation and Aβ1–42 Generation by the Aminotetrahydrofuran Derivative ANAVEX2-73, a Mixed Muscarinic and σ1 Receptor Agonist,in a Nontransgenic Mouse Model of Alzheimer's Disease

The main objective of the present study was to establish whether the mixed σ₁/muscarinic ligand ANAVEX2-73, shown to be neuroprotective in Alzheimer''s disease (AD) models in vivo and currently in clinical phase I/IIa, could have the ability to reduce the appearance of hyperphosphorylated Tau and amyloid-β_1–42 (Aβ_1–42) in the Aβ_25–35 mouse model of AD. We therefore first confirmed that Aβ_25–35 injection induced hyperphosphorylation of Tau protein, by showing that it rapidly decreased Akt activity and activated glycogen synthase kinase-3β (GSK-3β) in the mouse hippocampus. Second, we showed that the kinase activation, and resulting Tau alteration, directly contributed to the amyloid toxicity, as co-administration of the selective GSK-3β inhibitor 2-thio(3-iodobenzyl)-5-(1-pyridyl)-[1,3,4]-oxidiazole blocked both Tau phosphorylation and Aβ_25–35-induced memory impairments. Third, we analyzed the ANAVEX2-73 effect on Tau phosphorylation and activation of the related kinase pathways (Akt and GSK-3β). And fourth, we also addressed the impact of the drug on Aβ_25–35-induced Aβ_1–42 seeding and observed that the compound significantly blocked the increase in Aβ_1–42 and C99 levels in the hippocampus, suggesting that it may alleviate amyloid load in AD models. The comparison with PRE-084, a selective and reference σ₁ receptor agonist, and xanomeline, a muscarinic ligand presenting similar profile as ANAVEX2-73 on M1 and M2 subtypes, confirmed that both muscarinic and σ₁ targets are involved in the ANAVEX2-73 effects. The drug, acting synergistically on both targets, but with moderate affinity, presents a promising pharmacological profile.     

The exposure of highly toxic aconitine does not significantly impact the activity and expression of cytochrome P450 3A in rats determined by a novel ultra performance liquid chromatography–tandem mass spectrometric method of a specific probe buspirone

Aconitum species are widely used to treat rheumatism, cardiovascular diseases, and tumors in China and other Asian countries. The herbs are always used with drugs such as paclitaxel. Aconitine (AC) is one of the main bioactive/high-toxic alkaloids of Aconitum roots. AC is metabolized by cytochrome P450 (CYP) 3A. However, whether AC inhibits/induces CYP3A, which causes drug–drug interaction (DDI) is unclear. Our study aims to explore the potent effects of AC, as a marker component of Aconitum, on CYP3A using the probe buspirone in rats. The effects of oral AC on pharmacokinetics of buspirone were evaluated. CYP3A activity and protein levels in rat liver microsomes pretreated with oral AC were also measured using in vitro buspirone metabolism and Western blot. Buspirone and its major metabolites 1-(2-pyrimidinyl)piperazine and 6′-hydroxybuspirone were determined using a newly validated UPLC–MS/MS method. Single dose and 7-day AC administration at 0.125 mg/kg had no effect on CYP3A activity since no change in the formation of 1-(2-pyrimidinyl)piperazine and 6′-hydroxybuspirone. CYP3A activity and protein levels in liver microsomes were also not affected by 7-day AC pretreatment at 0.125 mg/kg. Therefore, AC neither inhibits nor induces CYP3A in rats, indicating AC does not cause CYP3A-related DDI in the liver.