Fine-Particle Ethylcellulose as a Tablet Binder in Direct Compression, Immediate-Release Tablets

Ethylcellulose has traditionally been used in tablets as a binder in an alcohol solution form. In the present study, fine-particle ethylcellulose (FPEC) was used as a binder to manufacture immediate-release tablets by the direct compression technique. The binding potential of FPEC is compared to that of commercially available coarse-particle ethylcellulose at the same viscosity grade and to that of hydrophilic binders. The compression force setting was kept constant for all batches. The concentration of the binder was varied from 5% to 25%. Acetaminophen was used as a model drug because capping is a problem frequently observed during high-speed compaction and further processing of acetaminophen tablets. In this study, there would be an increase in the contact area with FPEC and hence greater bond formation. This greater bond formation should be able to reduce the problem of capping in tablets containing highly elastic materials such as acetaminophen. Tablets were evaluated based on the following tests: weight variation, extent of capping, hardness, friability, disintegration, and dissolution. Based on the results of these tests, FPEC proved to be an effective binder for directly compressed acetaminophen tablets. The 10% and 15% formulations of FPEC passed all the tests and also produced the hardest tablets.     

High-level expression of bovine beta-lactoglobulin in Pichia pastoris and characterization of its physical properties

Bovine beta-lactoglobulin (BLG) variant A has been expressed in the methylotropic yeast Pichia pastoris by fusion of the cDNA to the sequence coding for the alpha-mating factor prepro-leader peptide from Saccharomyces cerevisiae. P. pastoris Mut+ transformants were obtained by single cross-over integration of the BLG-containing vector into the AOX1 locus. In a fed-batch fermenter, a cell density of approximately 300 mg/ml was achieved by controlled glycerol feeding for a total of 24 h. After 72 h of methanol induction, the secreted BLG reached levels of > 1 g/l. The secreted protein could be purified to homogeneity by ion-exchange chromatography. Amino-terminal sequencing of the secreted BLG revealed that the Glu-Ala spacer repeats inserted between the mature protein and the alpha-factor prepro-leader were still present. The purified protein was characterized by a number of methods, including CD spectroscopy, guanidine-HCl unfolding, crystallization and two-dimensional 1H-NMR spectroscopy. By all of these measures, the physical characteristics of recombinant BLG were indistinguishable from those of the native purified bovine BLG, making it useful as a model for protein folding and other biophysical studies.     

NH4Zr2V3O12 proton conductor

NH₄Zr₂V₃O₁₂, a new proton conductor, has been synthesized by flux, melt and hydrothermal methods. The crystals were subjected to X-ray diffraction, differential thermal analysis, infrared spectroscopy and impedance measurements.     

Two-point constraint approximation in structural optimization

The use of constraint approximations is recognized as a primary means of achieving computational efficiency in structural optimization. Existing approximation methods are based upon the value of the constraint function and its derivatives at a single point. The present paper explores the use of approximations based upon the value of the constraint and its derivative at two points. Several candidate approximations are suggested and tested for randomly generated rational constraint functions. Several of the approximations prove to be superior to the single-point approximations.     

Nanoporous biocapsules for the encapsulation of insulinoma cells:biotransport and biocompatibility considerations

This study investigates whether nanoporous micromachined biocapsules, with uniform membrane pore sizes of 24.5-nm, can be used to encapsulate insulin-secreting cells in vitro. This approach to cell encapsulation is based on microfabrication technology whereby immunoisolation membranes are bulk and surface micromachined to present uniform and well-controlled pore sizes as small as 10 nm, tailored surface chemistries, and precise microarchitectures. This study evaluates the behavior of insulinoma cells with micromachined membranes, the effect of matrix configurations within the biocapsule on cell behavior, as well as insulin and glucose transport through the biocapsule membranes.     

Maternal High‐Fat‐Diet Programs Rat Offspring Liver Fatty Acid Metabolism

In offspring exposed in utero to a maternal diet high in fat (HF), we have previously demonstrated that despite similar birth weights, HF adult offspring at 6 months of age had significantly higher body weights, greater adiposity, and increased triacylglycerol (TAG) levels as compared to controls. We hypothesized that a maternal HF diet predisposes to offspring adiposity via a programmed increase in the synthesis of monounsaturated fatty acids in the liver and hence increased substrate availability for liver TAG synthesis. We further hypothesized that programmed changes in offspring liver fatty acid metabolism are associated with increased liver expression of the lipogenic enzyme stearoyl‐CoA desaturase‐1 (SCD‐1). Female rats were maintained on a HF diet rich in monounsaturated fatty acids (MUFA) prior to and throughout pregnancy and lactation. After birth, newborns were nursed by the same dam, and all offspring were weaned to control diet. Plasma and liver fatty acid compositions were determined using gas chromatography/mass spectrometry. Fatty acid C16 desaturation indices of palmitoleic/palmitic and (vaccenic + palmitoleic)/palmitic and the C18 desaturation index of oleic/stearic were calculated. Liver protein abundance of SCD‐1 was analyzed in newborns and adult offspring. Plasma and liver C16 desaturation indices were decreased in HF newborns, but increased in the adult offspring. Liver SCD‐1 expression was increased in the HF adult offspring. These data show that the maternal HF diet during pregnancy and lactation increases offspring liver SCD‐1 protein abundance and alters the liver C16 desaturase pathway.     

Dielectric barrier discharge plasma induced surface modification of polyester/cotton blended fabrics to impart water repellency using HMDSO

Continuous treatment of polyester/cotton blended fabric samples was carried with hexamethyldisiloxane (HMDSO) plasma on the pilot scale atmospheric pressure plasma reactor. The mixture of helium and argon was used as carrier gas for generating dielectric barrier discharge plasma. The effect of discharge power and treatment time on the water repellent properties of samples were evaluated with contact angle (CA) and spray test measurements. Spray test and CA results showed improved resistance to wetting with water. The effect of discharge conditions on the surface morphology and surface chemistry of plasma treated samples were investigated by scanning electron microscopy (SEM) and Fourier transform infrared (FTIR) spectroscopic analysis, respectively. The presence of Si‐O‐Si and Si‐CH₃ groups in the structure of plasma polymer deposited at the surface of P/C samples was revealed by FTIR spectroscopy. Further, structural differences in HMDSO plasma polymer deposited under different discharge conditions were reported with reference to organic/inorganic nature of plasma polymer. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011.