Polymeric nanocapsules via miniemulsion polymerization using redox initiation

The effect of using a redox initiation system (hydrogen peroxide and ascorbic acid), on the morphology of the nanoparticles formed in methyl methacrylate miniemulsion polymerization reactions with lecithin as surfactant and using high amounts of miglyol 812 or castor oil as costabilizer is compared to the use of a conventional organic phase initiator (2,2′-azo-bis-isobutironitrile). It was observed that with miglyol 812 as co-stabilizer the preferential formation of the nanocapsule morphology was achieved with both evaluated initiation systems when initiator concentrations were chosen in such a way that monomer conversions of 90% were only attained after 30 min of reaction.     

Encapsulation of magnetic nickel nanoparticles via inverse miniemulsion polymerization

In this work, the encapsulation of magnetic nickel nanoparticles in polyacrylamide particles was performed via inverse miniemulsion polymerization. The dispersion of nickel nanoparticles was characterized in polar solvents including water, ethanol, and dimethyl sulfoxide using different stabilizers. The best results were obtained when the nonionic stabilizer poly(ethylene glycol) octadecyl ether (Brij 76) was used to stabilize the nickel nanoparticles in dimethyl sulfoxide. In addition, the block copolymer poly(ethylene‐co‐butylene)‐b‐poly(ethylene oxide) was used as a surfactant to create inverse miniemulsions while minimizing the coalescence of the miniemulsion droplets. Different types of salts such as zinc, nickel, and sodium nitrates were tested as lipophobes to retard Ostwald ripening. Transmission electron microscopy images of polyacrylamide/nickel particles synthesized with zinc and nickel salts as lipophobes indicate that nickel nanoparticles are embedded in the polyacrylamide matrix. Magnetization curves show that the saturation magnetization of polyacrylamide/nickel particles is only slightly below that of the pure nickel nanoparticles. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

Skeletal calcium retention in hyperthyroidism and in vitro calcitonin inactivation

A radio isotopic technique is described to measure and monitor the cerebral blood volume during a controlled arterial hypotension induced by sodium nitroprusside in anesthetised patients (neurolepanalgesia) submited to surgery for a ruptured saccular aneurysm. The study was made in 10 cases from 90 mm Hg to 30 mm Hg mean blood pressure monitored from a transducer connected to an intra humeral microcatheter. The figures obtained show an increase of the cerebral blood volume from 90 mm Hg to 50 mm Hg in every patient and a linear correlation when the pressure is lowered under 50 mm Hg level; therefore under a mean arterial pressure of 50 mm Hg the autoregulation arterial mechanism is out of work.     

Definition of essential amino acid residues in the recognition of a peptide by a mouse monoclonal antibody

A mouse monoclonal antibody reacting in ELISA with a synthetic peptide representing a linear amino acid stretch of the protein antigen was tested on all overlapping 5-mer to 9-mer fragments of the peptide, as prepared by multi-pin synthesis. Analysis of the binding data suggests that several residues in the peptide might be relatively unrelevant for recognition, while few others seem to play a critical role as key residues. On the basis of such observations, we attempted to reconstruct an alternative essential epitope by introducing multiple amino acid substitutions in the 9-mer peptide exhibiting the best binding activity, and then tested its ability to be recognized by the monoclonal antibody.     

Selective ''in synthesis'' labelling of peptides by fluorochromes

Very highly degenerate primers with short specific 3' anchor sequences and 5' adaptors were used in conjunction with nested specific primers to amplify large numbers of unknown insertion junctions of the insect retrotransposon Woot, using genomic DNA as template for the polymerase chain reaction (PCR). This technique, sometimes referred to as universal PCR, is a powerful method for molecular characterization of transposon insertions into genomes, and more generally for short-distance chromosome walking through unknown DNA. Twenty-four unique insertion junctions were cloned and sequenced from two strains of Tribolium castaneum and one strain of T. freemani. Inspection of these sequences revealed that integration of the Woot retrotransposon is cued by the insertion target motif, GTAC, in both species.