Development, Optimization, and Characterization of Solid Self-Nanoemulsifying Drug Delivery Systems of Valsartan Using Porous Carriers

The present studies entail formulation development of novel solid self-nanoemulsifying drug delivery systems (S-SNEDDS) of valsartan with improved oral bioavailability, and evaluation of their in vitro and in vivo performance. Preliminary solubility studies were carried out and pseudoternary phase diagrams were constructed using blends of oil (Capmul MCM), surfactant (Labrasol), and cosurfactant (Tween 20). The SNEDDS were systematically optimized by response surface methodology employing 3^3-Box–Behnken design. The prepared SNEDDS were characterized for viscocity, refractive index, globule size, zeta potential, and TEM. Optimized liquid SNEDDS were formulated into free flowing granules by adsorption on the porous carriers like Aerosil 200, Sylysia (350, 550, and 730) and Neusilin US2, and compressed into tablets. In vitro dissolution studies of S-SNEDDS revealed 3–3.5-fold increased in dissolution rate of the drug due to enhanced solubility. In vivo pharmacodynamic studies in Wistar rats showed significant reduction in mean systolic BP by S-SNEDDS vis-à-vis oral suspension (p < 0.05) owing to the drug absorption through lymphatic pathways. Solid-state characterization of S-SNEDDS using FT-IR and powder XRD studies confirmed lack of any significant interaction of drug with lipidic excipients and porous carriers. Further, the accelerated stability studies for 6 months revealed that S-SNEDDS are found to be stable without any change in physiochemical properties. Thus, the present studies demonstrated the bioavailability enhancement potential of porous carriers based S-SNEDDS for a BCS class II drug, valsartan.KEY WORDS: BCS, bioavailability, in vitro dissolution, porous carriers, XRD     

BioText Search Engine: beyond abstract search

The BioText Search Engine is a freely available Web-based application that provides biologists with new ways to access the scientific literature. One novel feature is the ability to search and browse article figures and their captions. A grid view juxtaposes many different figures associated with the same keywords, providing new insight into the literature. An abstract/title search and list view shows at a glance many of the figures associated with each article. The interface is carefully designed according to usability principles and techniques. The search engine is a work in progress, and more functionality will be added over time. Availability: http://biosearch.berkeley.edu.     

Mutations in exons 10 and 11 of human glucokinase result in conformational variations in the active site of the structure contributing to poor substrate binding – explains hyperglycemia in type 2 diabetic patients

Mutations in the glucokinase (GK) gene play a critical role in the establishment of type 2 diabetes. In our earlier study, R308K mutation in GK in a clinically proven type 2 diabetic patient showed, structural and functional variations that contributed immensely to the hyperglycemic condition. In the extension of this work, a cohort of 30 patients with established type 2 diabetic condition were chosen and the exons 10 and 11 of GK were PCR-amplified and sequenced. The sequence alignment showed A379S, D400Y, E300A, E395A, E395G, H380N, I348N, L301M, M298I, M381G, M402R, R308K, R394P, R397S, and S398R mutations in 12 different patients. The structural analysis of these mutated GKs, showed a variable number of β-α-β units, hairpins, β-bulges, strands, helices, helix–helix interactions, β-turns, and γ-turns along with the RMSD variations when compared to wild-type GK. Molecular modeling studies revealed that the substrate showed variable binding orientations and could not fit into the active site of these mutated structures; moreover, it was expelled out of the conformations. Therefore, these structural variations in GK due to mutations could be one of the strongest reasons for the hyperglycemic levels in these type 2 diabetic patients.     

Chemical Diversity in Himalayan Elsholtzia Species

The terpenoid composition of essential oils from the leaves of five Elsholtzia species, viz., E. eriostachya Benth ., E. cristata Willd ., E. polystachya Benth ., E. flava Benth ., and E. pilosa Benth ., collected from the Himalayan region (India), was examined by GC, GC/MS, and NMR analyses. Comparison of the results with previous reports revealed new chemotypes. Cluster analysis was carried out in order to discern the similarities and differences within the essential‐oil compositions at their subspecies/chemotype level. Based on the major constituents of the essential oils, six chemical groups were obtained.     

An Assessment of Growth Media Enrichment on Lipid Metabolome and the Concurrent Phenotypic Properties of Candida albicans

A critical question among the researchers working on fungal lipid biology is whether the use of an enriched growth medium can affect the lipid composition of a cell and, therefore, contribute to the observed phenotypes. One presumption is that enriched medias, such as YPD (yeast extract, peptone and dextrose), are likely to contain lipids, which may homogenize with the yeast lipids and play a role in masking the actual differences in the observed phenotypes or lead to an altered phenotype altogether. To address this issue, we compared the lipids of Candida albicans, our fungus of interest, grown in YPD or in a defined media such as YNB (yeast nitrogen base). Mass spectrometry-based lipid analyses showed differences in the levels of phospholipids, including phosphatidylinositol, phosphatidylglycerol, lyso-phospholipids; sphingolipids, such as mannosyldiinositolphosphorylceramide; and sterols, such as ergostatetraenol. Significant differences were observed in 70 lipid species between the cells grown in the two media, but the two growth conditions did not affect the morphological characteristics of C. albicans. The lipid profiles of the YNB- and YPD-grown C. albicans cells did vary, but these differences did not influence their response to the majority of the tested agents. Rather, the observed differences could be attributed to the slow growth rate of the Candida cells in YNB compared to YPD. Notably, the altered lipid changes between the two media did impact the susceptibility to some drugs. This data provided evidence that changes in media can lead to certain lipid alterations, which may affect specific pathways but, in general, do not affect the majority of the phenotypic properties of C. albicans. It was determined that either YNB or YPD may be suitable for the growth and lipid analysis of C. albicans, depending upon the experimental requirements, but additional precautions are necessary when correlating the phenotypes with the lipids.     

Venom Concentrations and Clotting Factor Levels in a Prospective Cohort of Russell’s Viper Bites with Coagulopathy

Background

Russell’s viper envenoming is a major problem in South Asia and causes venom induced consumption coagulopathy. This study aimed to investigate the kinetics and dynamics of venom and clotting function in Russell’s viper envenoming.

Methodology/Principal Findings

In a prospective cohort of 146 patients with Russell’s viper envenoming, we measured venom concentrations, international normalised ratio [INR], prothrombin time (PT), activated partial thromboplastin time (aPTT), coagulation factors I, II, V, VII, VIII, IX and X, and von Willebrand factor antigen. The median age was 39y (16–82y) and 111 were male. The median peak INR was 6.8 (interquartile range[IQR]:3.7 to >13), associated with low fibrinogen [median,<0.01g/L;IQR:<0.01–0.9g/L), low factor V levels [median,<5%;IQR:<5–4%], low factor VIII levels [median,40%;IQR:12–79%] and low factor X levels [median,48%;IQR:29–67%]. There were smaller reductions in factors II, IX and VII over time. All factors recovered over 48h post-antivenom. The median INR remained >3 at 6h post-antivenom but had reduced to <2, by 24h. The aPTT had also returned to close to normal (<50sec) at 24h. Factor VII, VIII and IX levels were unusually high pre-antivenom, median peak concentrations of 393%, 307% and 468% respectively. Pre-antivenom venom concentrations and the INR (r = 0.20, p = 0.02) and aPTT (r = 0.19, p = 0.03) were correlated (non-parametric Spearman analysis).

Conclusions

Russell’s viper coagulopathy results in prolonged aPTT, INR, low fibrinogen, factors V, VIII and X which recover over 48h. Severity of clotting abnormalities was associated with venom concentrations.     

Gelatin grafted poly(D,L-lactide) as an inhibitor of protein aggregation: An in vitro case study

Amyloids are a group of proteins that are capable of forming aggregated amyloid fibrils, which is responsible for many neurodegenerative diseases including Alzheimer's disease (AD). In our previous study, synthesis and characterization of star-shaped poly(D,L-lactide)-b-gelatin (ss-pLG) have been reported. In the present work, we have extended our work to study ss-pLG against protein aggregation. To the best of our knowledge, this is the first report on the inhibition of amyloid fibrillation by protein grafted poly(D,L-lactide). Bovine serum albumin (BSA) was chosen as the model protein, which readily forms fibril under high temperature. We found that ss-pLG efficiently suppressed the fibril formation of BSA compared with gelatin (Gel), which was supported by Thioflavin T assay, circular dichroism (CD) spectroscopy and atomic force microscopy (AFM). In addition, ss-pLG significantly curtailed amyloid-induced hemolysis. We also found that incubation of ss-pLG with neuroblastoma cells (MC65) protected the cells from fibril-induced toxicity. The rescuing efficiency of ss-pLG was better than Gel, which could be attributed to the reduced lamella thickness in branched ss-pLG. These results suggest the significance of gelatin grafting, which probably allows gelatin to interact with the key residues of the amyloidogenic core of BSA effectively.