Anti-Pfs25 Human Plasma Reduces Transmission of Plasmodium falciparum Isolates That Have Diverse Genetic Backgrounds

Pfs25 is a leading candidate for a malaria transmission-blocking vaccine whose potential has been demonstrated in a phase 1 trial with recombinant Pfs25 formulated with Montanide ISA51. Because of limited sequence polymorphism, the anti-Pfs25 antibodies induced by this vaccine are likely to have transmission-blocking or -reducing activity against most, if not all, field isolates. To test this hypothesis, we evaluated transmission-blocking activities by membrane feeding assay of anti-Pfs25 plasma from the Pfs25/ISA51 phase 1 trial against Plasmodium falciparum parasites from patients in two different geographical regions of the world, Thailand and Burkina Faso. In parallel, parasite isolates from these patients were sequenced for the Pfs25 gene and genotyped for seven microsatellites. The results indicate that despite different genetic backgrounds among parasite isolates, the Pfs25 sequences are highly conserved, with a single nonsynonymous nucleotide polymorphism detected in 1 of 41 patients in Thailand and Burkina Faso. The anti-Pfs25 immune plasma had significantly higher transmission-reducing activity against parasite isolates from the two geographical regions than the nonimmune controls (P < 0.0001).     

Development of Imiquimod-Loaded Mucoadhesive Films for Oral Dysplasia

Oral squamous dysplasia, which can usually be readily visualized as leukoplakia during an oral examination and confirmed by histology, is often considered a premalignant condition. Current treatments, however, focus on the final stages of disease, and treatments such as surgery can lead to postoperative disabilities. Hence, this study was designed to develop a noninvasive, mucoadhesive drug delivery system loaded with an immune response modifier, imiquimod, as a treatment for precancerous dysplastic lesions. Blends of polyvinylpyrrolidone and carboxymethylcellulose were used to prepare mucoadhesive films that were backed with poly(ethylene-co-vinyl acetate). Because of the hydrophobic nature of imiquimod, four loading methods (sonication, linoleic acid, 2-hydroxypropyl-β-cyclodextrin, and acetate buffer) were compared. The formation of imiquimod–cyclodextrin complexes and their solubility was studied by differential scanning calorimetry and phase solubility studies. All films achieved sustained release of drug for 3 h except those prepared by linoleic acid. The high solubility of imiquimod in acetate buffer facilitated high loading capacity and greater release (68%) of drug than did the other formulations (approximately 40%). In summary, a noninvasive and local approach with the potential to treat precancerous lesions may be achieved by this described mucoadhesive drug delivery system. © 2012 Wiley Periodicals, Inc. and the American Pharmacists Association J Pharm Sci 102:593–603, 2013     

Colon-specific mutual amide prodrugs of 4-aminosalicylic acid for their mitigating effect on experimental colitis in rats

Mutual amide prodrugs of 4-aminosalicylic acid with D-phenylalanine and L-tryptophan were synthesized for targeted drug delivery to the inflamed gut tissue in inflammatory bowel disease. Stability studies in aqueous buffers (pH 1.2 and 7.4) showed that the synthesized prodrugs were stable in both the buffers over a period of 10 h. In rat fecal matter the release of 4-aminosalicylic acid from the prodrugs was in the range of 86-91% over a period of 20 h, with half-lives ranging between 343 and 412 min following first order kinetics. Targeting potential of the carrier system and the ameliorating effect of the amide conjugates were evaluated in trinitrobenzenesulfonic acid-induced experimental colitis model in rats. The prodrugs were assessed for their probable damaging effects on pancreas and liver with the help of histopathological analysis and for their ulcerogenic potential by Rainsford's cold stress method. They were found to have improved safety profile than sulfasalazine, oral 4- and 5-aminosalicylic acid with similar pharmacological spectrum and advantages of sulfasalazine.     

Transdermal delivery of fentanyl from matrix and reservoir systems: Effect of heat and compromised skin

The United States Food and Drug Administration (FDA) has received numerous reports of serious adverse events, including death, in patients using fentanyl transdermal systems (FTS). To gain a better understanding of these problems, the current research focuses on the in vitro characterization of fentanyl reservoir (Duragesic®) and matrix (Mylan) systems with respect to drug release and skin permeation under conditions of elevated temperature and compromised skin. In addition, different synthetic membrane barriers were evaluated to identify the one that best simulates fentanyl skin transport, and thus may be useful as a model for these systems in future studies. The results indicate that reservoir and matrix FTS are comparable when applied to intact skin at normal skin temperature but the kinetics of drug delivery are different in the two systems. At 40°C, the permeation rate of fentanyl was twice that seen at 32°C over the first 24 h in both systems; however, the total drug permeation in 72 h is significantly higher in the reservoir FTS. When applied to partially compromised skin, matrix FTS has a greater permeation enhancement effect than reservoir FTS. The intrinsic rate limiting membrane of the reservoir system served to limit drug permeation when the skin (barrier) permeability was compromised. Different ethylene vinyl acetate membranes were shown to have fentanyl permeability values encompassing the variability in human skin. Results using the in vitro model developed using synthetic membranes suggest that they mimic the effect of compromised skin on fentanyl permeability. Especially for highly potent drugs such as fentanyl, it is important that patients follow instructions regarding application of heat and use of the product on compromised skin. © 2009 Wiley‐Liss, Inc. and the American Pharmacists Association J Pharm Sci 99: 2357–2366, 2010     

RGS14 is a natural suppressor of both synaptic plasticity in CA2 neurons and hippocampal-based learning and memory

Learning and memory have been closely linked to strengthening of synaptic connections between neurons (i.e., synaptic plasticity) within the dentate gyrus (DG)–CA3–CA1 trisynaptic circuit of the hippocampus. Conspicuously absent from this circuit is area CA2, an intervening hippocampal region that is poorly understood. Schaffer collateral synapses on CA2 neurons are distinct from those on other hippocampal neurons in that they exhibit a perplexing lack of synaptic long-term potentiation (LTP). Here we demonstrate that the signaling protein RGS14 is highly enriched in CA2 pyramidal neurons and plays a role in suppression of both synaptic plasticity at these synapses and hippocampal-based learning and memory. RGS14 is a scaffolding protein that integrates G protein and H-Ras/ERK/MAP kinase signaling pathways, thereby making it well positioned to suppress plasticity in CA2 neurons. Supporting this idea, deletion of exons 2–7 of the RGS14 gene yields mice that lack RGS14 (RGS14-KO) and now express robust LTP at glutamatergic synapses in CA2 neurons with no impact on synaptic plasticity in CA1 neurons. Treatment of RGS14-deficient CA2 neurons with a specific MEK inhibitor blocked this LTP, suggesting a role for ERK/MAP kinase signaling pathways in this process. When tested behaviorally, RGS14-KO mice exhibited marked enhancement in spatial learning and in object recognition memory compared with their wild-type littermates, but showed no differences in their performance on tests of nonhippocampal-dependent behaviors. These results demonstrate that RGS14 is a key regulator of signaling pathways linking synaptic plasticity in CA2 pyramidal neurons to hippocampal-based learning and memory but distinct from the canonical DG–CA3–CA1 circuit.     

Colon-specific prodrugs of 4-aminosalicylic acid for inflammatory bowel disease

Despite the advent of biological products,such as antitumor necrosis factor-αmonoclonal antibodies(infliximab and adalimumab),for treatment of moderate to severe cases of inflammatory bowel disease(IBD),most patients depend upon aminosalicylates as the conventional treatment option.In recent years,the increased knowledge of complex pathophysiological processes underlying IBD has resulted in development of a number of newer pharmaceutical agents like low-molecular-weight heparin,omega-3 fatty acids,probiotics and innovative formulations such as high-dose,oncedaily multi-matrix mesalamine,which are designed to minimize the inflammatory process through inhibition of different targets.Optimization of delivery of existing drugs to the colon using the prodrug approach is another attractive alternative that has been utilized and commercialized for 5-aminosalicylic acid(ASA)in the form of sulfasalazine,balsalazide,olsalazine and ipsalazine,but rarely for its positional isomer 4-ASA-a wellestablished antitubercular drug that is twice as potent as 5-ASA against IBD,and more specifically,ulcerativecolitis.The present review focuses on the complete profile of 4-ASA and its advantages over 5-ASA and colon-targeting prodrugs reported so far for the management of IBD.The review also emphasizes the need for reappraisal of this promising but unexplored entity as a potential treatment option for IBD.