Formulation and development of ophthalmic in situ gel for the treatment ocular inflammation and infection using application of quality by design concept

Context: The conventional liquid ophthalmic delivery systems exhibit short pre-corneal residence time and the relative impermeability to the cornea which leads to poor ocular bioavailability.

Objective: The aim of this study was to apply quality by design (QbD) for development of dexamethasone sodium phosphate (DSP) and tobramycin sulfate (TS)-loaded thermoresponsive ophthalmic in situ gel containing Poloxamer 407 and hydroxyl propyl methyl cellulose (HPMC) K4M for prolonging the pre-corneal residence time, ocular bioavability and decreases the frequency of administration of dosage form. The material attributes and the critical quality attributes (CQA) of the in situ gel were identified. Central composite design (CCD) was adopted to optimize the formulation.

Materials and methods: The ophthalmic in situ forming gels were prepared by cold method. Materials attributes were the amount of Poloxamer 407 and HPMC and CQA identified were Gel strength, mucoadhesive index, gelation temperature and % of drug release of both drug.

Results and discussion: Optimized batch (F*) containing 16.75% poloxamer 407 and 0.54% HPMC K4M were exhibited all results in acceptable limits. Compared with the marketed formulation, optimized in situ gel showed delayed T_max, improved C_max and AUC in rabbit aqueous humor, suggesting the sustained drug release and better corneal penetration and absorption.

Conclusion: According to the study, it could be concluded that DSP and TS would be successfully formulated as in situ gelling mucoadhesive system for the treatment of steroid responsive eye infections with the properties of sustained drug release, prolonged ocular retention and improved corneal penetration.     

Moment Distribution around Circular/Elliptical/Triangular Cutouts in Infinite Symmetric Laminated Plate

In this article, a general solution for moment distribution around a circular/elliptical/triangular shaped hole in a laminated composite plate subjected to a bending/twisting moment at infinity is presented. The numerical results are obtained for graphite/epoxy, glass/epoxy, boron/epoxy, etc. The effect of loading factor, stacking sequence, material parameters, and hole geometry on moment distribution is studied for cross ply and angle ply laminates. The results are compared with existing literature and found to be in good agreement.     

Additional modules for versatile and economical PCR-based gene deletion and modification in Saccharomyces cerevisiae

An important recent advance in the functional analysis of Saccharomyces cerevisiae genes is the development of the one-step PCR-mediated technique for deletion and modification of chromosomal genes. This method allows very rapid gene manipulations without requiring plasmid clones of the gene of interest. We describe here a new set of plasmids that serve as templates for the PCR synthesis of fragments that allow a variety of gene modifications. Using as selectable marker the S. cerevisiae TRP1 gene or modules containing the heterologous Schizosaccharomyces pombe his5⁺ or Escherichia coli kan^r gene, these plasmids allow gene deletion, gene overexpression (using the regulatable GAL1 promoter), C- or N-terminal protein tagging [with GFP(S65T), GST, or the 3HA or 13Myc epitope], and partial N- or C-terminal deletions (with or without concomitant protein tagging). Because of the modular nature of the plasmids, they allow efficient and economical use of a small number of PCR primers for a wide variety of gene manipulations. Thus, these plasmids should further facilitate the rapid analysis of gene function in S. cerevisiae. © 1998 John Wiley & Sons, Ltd.     

Brominated flame retardants in US food

We and others recently began studying brominated flame retardant levels in various matrices in the US including human milk and other food. This paper reviews the food studies. In our studies, ten to thirteen polybrominated diphenyl ether (PBDE) congeners were measured, usually including BDE 209. All US women's milk samples were contaminated with PBDEs from 6 to 419 ng/g, lipid, orders of magnitude higher than levels reported in European studies, and are the highest reported worldwide. We compared our market basket studies of meat, fish and dairy products with other US food studies of meat and fish. US studies showed somewhat higher levels of PBDEs than reported elsewhere. Fish were most highly contaminated (median 616 pg/g), then meat (median190 pg/g) and dairy products (median 32.2 pg/g). However, unlike some European countries where fish predominates, dietary intake of PBDEs in the US is mostly from meat, then fish and then dairy products. Broiling can decrease the amount of PBDEs per serving. We also measured levels of hexabromocyclododecane (HBCD), another brominated flame retardant, in human milk. The levels are lower than PBDEs, 0.16-1.2 ng/g, similar to European levels, unlike PBDEs where US levels are much higher than European levels.     

Power generation and organics removal from wastewater using activated carbon nanofiber (ACNF) microbial fuel cells (MFCs)

Carbon-based materials are the most commonly used electrode material for anodes in microbial fuel cell (MFC), but are often limited by their surface areas available for biofilm growth and subsequent electron transfer process. This study investigated the use of activated carbon nanofibers (ACNF) as the anode material to enhance bacterial biofilm growth, and improve MFC performance. Qualitative and quantitative biofilm adhesion analysis indicated that ACNF exhibited better performance over the other commonly used carbon anodes (granular activated carbon (GAC), carbon cloth (CC)). Batch-scale MFC tests showed that MFCs with ACNF and GAC as anodes achieved power densities of 3.50 ± 0.46 W/m³ and 3.09 ± 0.33 W/m³ respectively, while MFCs with CC had a lower power density of 1.10 ± 0.21 W/m³ In addition, the MFCs with ACNF achieved higher contaminant removal efficiency (85 ± 4%) than those of GAC (75 ± 5%) and CC (70 ± 2%). This study demonstrated the distinct advantages of ACNF in terms of biofilm growth and electron transport. ACNF has a potential for higher power generation of MFCs to treat wastewaters.     

Investigation of solid supported dendrimers for water disinfection

Polystyrene copolymer beads supported dendrimer was synthesized and investigated for its biological applications. Macroporous cross‐linked polystyrene copolymer beads were synthesized using suspension polymerization. Two successive generations of di(chloroethyl) amine‐type end group functionality was formed on the polystyrene copolymer beads. Elemental analysis, Fourier transform infrared spectra, and solid state ¹³C NMR spectra were employed to characterize the polymer bound dendrimer. The polymer bound dendrimer was tested for antibacterial action against both Gram‐positive and Gram‐negative bacteria. The activity against both types of organism increased with an increase in the nitrogen atoms in the polymer back bone. The dendritic structure containing both amino and di(chloroethyl) groups showed significant reduction in the bacterial count when kept in 20 mL autoclaved water with bacterial cultures having an initial count in the range of 12–83 × 10⁶ CFU/mL. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

Varietal Selection of Some Indica Rice for Production of Puffed Rice

Puffed rice is one of the popular snacks in India, which is prepared from pregelatinized milled rice usually by sand roasting method. Twelve varieties of indica rice were screened for the best puffing quality based on their chemical composition and physical characteristics such as amylose content, protein content, length, width, thickness, hardness, husk content, true density, and bulk density. The data were analyzed using Pearson’s correlation, and a strong positive correlation was found to exist between amylose content and expansion ratio. At the same time, protein content was found to be negatively related with amylose content, length expansion ratio, and volume expansion ratio. From the analysis Gurjari, Jaya, GR-5, and GR-6 varieties were found to be suitable for puffing.     

Designing carbon materials with unique shapes using polymer blending and coating techniques

Three carbon materials having unique and precise shapes were prepared using a polymer blend technique and coating as an auxiliary technique. The polymer blend consists essentially of two kinds of polymers, i.e. a carbon precursor polymer and a decomposable polymer which disappears by pyrolysis without leaving a carbon residue. One of the carbon materials prepared is a carbon fiber including many thin pores, with diameters of sub-μm to 1 μm, elongated along the fiber axis. The next is a carbon tube including a large amount of thin carbon fibers aligned densely along the tube surface. The last one is a microscopic multi-walled carbon tube consisting of three or four walls. The preparation procedures and SEM photographs of these materials are presented and possible applications are discussed briefly.