Amino acid-modified spray-dried powders with enhanced aerosolisation properties for pulmonary drug delivery

In this study, the amino acids arginine, aspartic acid, leucine, phenylalanine and threonine were investigated as 'dispersibility enhancers' in spray-dried powders for inhalation. Parameters such as spray-dried yield, tapped density, and Carr's Index were not predictive of aerosolisation performance. In addition, whilst the majority of amino acid-modified powders displayed suitable particle size distribution for pulmonary administration and potentially favourable low moisture content, in vitro particle deposition was only enhanced for the leucine-modified powder. In summary, leucine can be used to enhance the dispersibility and aerosolisation properties of spray-dried powders for pulmonary drug delivery. © 2007 Elsevier B.V. All rights reserved.

Gingipains from Porphyromonas gingivalis increase the chemotactic and respiratory burst-priming properties of the 77-amino-acid interleukin-8 variant

Porphyromonas gingivalis, a gram-negative anaerobe which is implicated in the etiology of active periodontitis, secretes degradative enzymes (gingipains) and sheds proinflammatory mediators (e.g., lipopolysaccharides [LPS]). LPS triggers the secretion of interleukin-8 (IL-8) from immune (72-amino-acid [aa] variant [IL-8(72aa)]) and nonimmune (IL-8(77aa)) cells. IL-8(77aa) has low chemotactic and respiratory burst-inducing activity but is susceptible to cleavage by gingipains. This study shows that both R- and K-gingipain treatments of IL-8(77aa) significantly enhance burst activation by fMLP and chemotactic activity (P < 0.05) but decrease burst activation and chemotactic activity of IL-8(72aa) toward neutrophil-like HL60 cells and primary neutrophils (P < 0.05). Using tandem mass spectrometry, we have demonstrated that R-gingipain cleaves 5- and 11-aa peptides from the N-terminal portion of IL-8(77aa) and the resultant peptides are biologically active, while K-gingipain removes an 8-aa N-terminal peptide yielding a 69-aa isoform of IL-8 that shows enhanced biological activity. During periodontitis, secreted gingipains may differentially affect neutrophil chemotaxis and activation in response to IL-8 according to the cellular source of the chemokine.

Sex steroids and intestinal amino acid transport in rainbow trout, Salmo airdneri Richardson

The effects of sane anabolic and naturally-occuring sex steroids on intestinal transport of leucine have been studied in rainbow trout (Sallno gairdneri), in vivo (gut perfusion), and in vitro (everted gut sacs or intestinal strips). Administration of 17a-methyltestosterone (Mr) by injection for a prolo03ed period of time, enhanced intestinal transport and accumulation of leucine. 11-ketotestosterone (KT) or MT treatment in vitro, by direct addition to incubation media, elicited significant short-term increases in active transport of leucine, without effecting intestinal accumulation. Luminal administration of Mr in vivo similarly elicited short-term responses, without effecting leucine accumulation in the intestine or other peripheral tissues. However; neither MT nor KT significantly affected intestinal transport of water in trout. Although long term injection of oestradiol (E2) enhanced intestinal transport and accumulation of leucine, E2 treatment in vitro was without effect. Addition of ouabain or 2,4,dinitrophenol in the presence of MT abolished steroid-stimulated leucine transform, in vitro. No significant differences were observed between immature male or female trout with respect to either transport of leucine and water, or intestinal granular cell density. However, 'apparent' Na+ absorption and percentage fold height were higher in females, while total intestinal thickness and enterocyte heights were greater in males. These sex differences were essentially abolished. after gonadectany. It is suggested that the short-term effects of the androgenic steroids might be partly mediated through increased activity of Na+,K+,ATPase, and that steroid-induced growth promotion in fish may,to sane extent, be a consequence of enhanced efficiency of intestinal function.

Structure-function analysis of amino acid 74 of human RAMP1 and RAMP3 and its role in peptide interactions with adrenomedullin and calcitonin gene-related peptide receptors

The receptors for calcitonin gene-related peptide (CGRP) and adrenomedullin (AM) are complexes of the calcitonin receptor-like receptor (CLR) and receptor activity-modifying proteins (RAMP). The CGRP receptor is a CLR/RAMP1 pairing whereas CLR/RAMP2 and CLR/RAMP3 constitute two subtypes of AM receptor: AM(1) and AM(2), respectively. Previous studies identified Glu74 in RAMP3 to be important for AM binding and potency. To further understand the importance of this residue and its equivalent in RAMP1 (Trp74) we substituted the native amino acids with several others. In RAMP3, these were Trp, Phe, Tyr, Ala, Ser, Thr, Arg and Asn; in RAMP1, Glu, Phe, Tyr, Ala and Asn substitutions were made. The mutant RAMPs were co-expressed with CLR in Cos7 cells; receptor function in response to AM, AM(2)/intermedin and CGRP was measured in a cAMP assay and cell surface expression was determined by ELISA. Phe reduced AM potency in RAMP3 but had no effect in RAMP1. In contrast, Tyr had no effect in RAMP3 but enhanced AM potency in RAMP1. Most other substitutions had a small effect on AM potency in both receptors whereas there was little impact on CGRP or AM(2) potency. Overall, these data suggest that the geometry and charge of the residue at position 74 contribute to how AM interacts with the AM(2) and CGRP receptors and confirms the role of this position in dictating differential AM pharmacology at the AM(2) and CGRP receptors.

On the utility of alternative amino acid scripts

In this work we propose the hypothesis that replacing the current system of representing the chemical entities known as amino acids using Latin letters with one of several possible alternative symbolic representations will bring significant benefits to the human construction, modification, and analysis of multiple protein sequence alignments. We propose ways in which this might be done without prescribing the choice of actual scripts used. Specifically we propose and explore three ways to encode amino acid texts using novel symbolic alphabets free from precedents. Primary orthographic encoding is the direct substitution of a new alphabet for the standard, Latin-based amino acid code. Secondary encoding imposes static residue groupings onto the orthography of the alphabet by manipulating the shape and/or orientation of amino acid symbols. Tertiary encoding renders each residue as a composite symbol; each such symbol thus representing several alternative amino acid groupings simultaneously. We also propose that the use of a new group-focussed alphabet will free the colouring of amino acid residues often used as a tool to facilitate the representation or construction of multiple alignments for other purposes, possibly to indicate dynamic properties of an alignment such as position-wise residue conservation.

Investigation of formulation and process of lyophilised orally disintegrating tablet (ODT) using novel amino acid combination

Lyophilised orally disintegrating tablets (ODTs) have achieved a great success in overcoming dysphagia associated with conventional solid dosage forms. However, the extensive use of saccharides within the formulation limits their use in treatment of chronic illnesses. The current study demonstrates the feasibility of using combination of proline and serine to formulate zero sacharide ODTs and investigates the effect of freezing protocol on sublimation rate and tablets characteristics. The results showed that inclusion of proline and serine improved ODT properties when compared to individual counterparts. Additionally, annealing the ODTs facilitated the sublimation process and shortened the disintegration time. © 2010 by the authors; licensee Molecular Diversity Preservation International, Basel, Switzerland.