Synthesis, Kinetic Evaluation and Utilization of a Biotinylated Dipeptide Proline Diphenyl Phosphonate for the Disclosure of Dipeptidyl Peptidase IV-like Serine Proteases

In this study, we report on the synthesis, kinetic characterisation, and application of a novel biotinylated and active site-directed inactivator of dipeptidyl peptidase IV (DPP-IV). Thus, the dipeptide-derived proline diphenyl phosphonate NH(2)-Glu(biotinyl-PEG)-Pro(P)(OPh)(2) has been prepared by a combination of classical solution- and solid-phase methodologies and has been shown to be an irreversible inhibitor of porcine DPP-IV, exhibiting an over all second-order rate constant (k(i)/K(i)) for inhibition of 1.57 x 10(3) M(-1) min(-1). This value compares favourably with previously reported rates of inactivation of DPP-IV by dipeptides containing a P(1) proline diphenyl phosphonate grouping [B. Boduszek, J. Oleksyszyn, C.M. Kam, J. Selzler, R.E. Smith, J.C. Powers, Dipeptide phophonates as inhibitors of dipeptidyl peptidase IV, J. Med. Chem. 37 (1994) 3969-3976; B.F. Gilmore, J.F. Lynas, C.J. Scott, C. McGoohan, L. Martin, B. Walker, Dipeptide proline diphenyl phosphonates are potent, irreversible inhibitors of seprase (FAPalpha), Biochem, Biophys. Res. Commun. 346 (2006) 436-446.], thus demonstrating that the incorporation of the side-chain modified (N-biotinyl-3-(2-(2-(3-aminopropyloxy)-ethoxy)-ethoxy)-propyl) glutamic acid residue at the P(2) position is compatible with inhibitor efficacy. The utilisation of this probe for the detection of both purified dipeptidyl peptidase IV and the disclosure of a dipeptidyl peptidase IV-like activity from a clinical isolate of Porphyromonas gingivalis, using established electrophoretic and Western blotting techniques previously developed by our group, is also demonstrated.

Coexistence among native and introduced freshwater amphipods (Crustacea); habitat utilization patterns in littoral habitats

Studies of biological invasions predominantly stress threats to biodiversity through the elimination and replacement of native species. However, we must realise that resident communities may often be capable of integrating invaders, leading to patterns of coexistence. Within the past ninety years, three freshwater amphipod species have invaded Northern Ireland the North American Gammarus tigrinus and Crangonyx pseudogracilis, plus the European G. pulex. These species have come into contact with the ubiquitous native species, G. duebeni celticus. This study examined spatiotemporal patterns of stability of single and mixed species assemblages in an invaded lake. Lough Beg and its associated rivers were surveyed in summer 1994 and winter 1995, and a selection of stations re-sampled in summer one and five years later. All possible combinations of the four amphipod species were found. Although species presence/absence was stable between seasons at the scale of the whole lough, it was extremely fluid at the scale of individual sites, 82% of which changed in species composition between seasons. Overall mean amphipod abundance was similar across 5 distinguishable habitat types, but there were differences in species compositions among these habitats. In addition, although co-occurrences of Gammarus species did not differ from random, there was a strong negative association between Gammarus spp. and C. pseudogracilis. This latter pattern was at least in part generated by the better tolerance of C. pseudogracilis to lower water quality. A review of previous studies indicates that the exclusion of C. pseudogracilis by Gammarus species from high water quality areas is likely to involve biotic interaction. Thus, overall, co-existence of the four species, which is clearly dynamic and scale-dependent, appears promoted by spatial and temporal habitat heterogeneity. However, biotic interactions may also play a role in local exclusions. Since the three introduced species have not eliminated the native species, and each successive invasion has not replaced the previous invader, this study demonstrates that freshwater invaders may integrate with native communities leading to coexistence and increased species diversity.

Utilization of the three-dimensional volcano surface to understand the chemistry of multiphase systems in heterogeneous catalysis

CO hydrogenation is used as a model system to understand why multiphase catalysts are chemically important in heterogeneous catalysis. By including both adsorption and subsequent surface reactions, kinetic equations are derived with two fundamental properties, the chemisorption energies of C and O (Delta H-C and Delta H-O, respectively). By plotting the activity against Delta H-C and Delta H-O, a 3-D volcano surface is obtained. Because of the constraint between Delta H-C and Delta H-O on monophase systems, a maximum can be achieved. However, if multiphase systems are used, such a constraint can be released and the global maximum may be achieved.

Utilization of analgesics, sedatives, and pain scores in infants with a prolonged hospitlaization: A prospective descriptive cohort study

Aim
Describe the utilization of analgesic and sedative medications and documentation of pain scores in a cohort of critically ill infants in a neonatal intensive care unit.

Method
A prospective, longitudinal, cohort study of infants with a predicted length of stay =28 days. Dosages and routes of administration of analgesic and sedative medications and documentation of pain scores were collected on a daily basis.

Results
55 infants were enrolled into the study. Oral sucrose was administered to all 55 infants, 51 infants (93%) were administered enteral acetaminophen and 50 (91%) infants were administered morphine during their hospitalization. Sedatives were administered to 42 infants (76%); 36 (65%) were administered chloral hydrate and 32 (58%) were administered intravenous midazolam. With the exception of the first week of admission, when there was highest utilization of opioids and lower use of sucrose, acetaminophen and sedatives, the pattern of administration of analgesic and sedative agents remained relatively constant throughout the hospitalization. Pain scores were documented for 36 (65%) infants during their hospitalisation, however for these 36 infants, pain scores were infrequently recorded.

Conclusion
There was substantial and varied analgesic and sedative use in this cohort of infants, yet infrequent documentation of pain assessment scores. These practices highlight important clinical implications for sick infants requiring careful consideration of pain and distress management.

Potential for phosphonoacetate utilization by marine bacteria in temperate coastal waters

Phosphonates are organic compounds that contain a C-P bond and are a poorly characterized component of the marine phosphorus cycle. They may represent a potential source of bioavailable phosphorus, particularly in oligotrophic conditions. This study has investigated the distribution of the phnA gene which encodes phosphonoacetate hydrolase, the enzyme that mineralizes phosphonoacetate. Using newly designed degenerate primers targeting the phnA gene we analysed the potential for phosphonoacetate utilization in DNA and cDNA libraries constructed from a phytoplankton bloom in the Western English Channel during July 2006. Total RNA was isolated and reverse transcribed and phosphonoacetate hydrolase (phnA) transcripts were PCR amplified from the cDNA with the degenerate primers, cloned and sequenced. Phylogenetic analysis demonstrated considerable diversity with 14 sequence types yielding five unique phnA protein groups. We also identified 28 phnA homologues in a 454-pyrosequencing metagenomic and metatranscriptomic study from a coastal marine mesocosm, indicating that > 3% of marine bacteria in this study contained phnA. phnA homologues were also present in a metagenomic fosmid library from this experiment. Finally, cultures of four isolates of potential coral pathogens belonging to the Vibrionaceae contained the phnA gene. In the laboratory, these isolates were able to grow with phosphonoacetate as sole P and C source. The fact that the capacity to utilize phosphonoacetate was evident in each of the three coastal environments suggests the potential for widespread utilization of this bioavailable P source.

Hydrophobic ionic liquids incorporating N-alkylisoquinolinium cations and their utilization in liquid-liquid separations

The first examples of Room Temperature Ionic Liquids (RTIL) containing fused polycyclic N-alkylisoquinolinium cations ([C(n)isoq](+)) in combination with the bis(perfluoroethylsulfonyl) imide anion ([BETI](-)) have been synthesized, characterized, and utilized in liquid-liquid partitioning from water; these salts have unexpectedly low melting points and give high distribution ratios for aromatic solutes, especially chlorobenzenes, between the RTIL and water.