Ventilatory care in a selection of Ontario hospitals: bigger is not necessarily better! Critical Care Research Network (CCR-Net)

Critical care nursing education and practice in Canada and Australia: a comparative review

Critical care nursing is an area of policy concern with respect to staffing projections, skill mix and educational preparation in both Canada and Australia. Despite many similarities between the health systems of these two countries, differences exist in both undergraduate and graduate specialty nursing education. In Australia, specialist education is primarily delivered via the tertiary sector as a formalised qualification, whereas the current Canadian model displays significant variation in duration, content, and mode of delivery. This paper provides a comparative perspective on the educational preparation of critical care nurses in these two countries. Consideration of alternative models of specialty nursing education may provide a method to improve recruitment and retention of staff while maintaining quality of care.

Practice Variation in Respiratory Therapy Documentation During Mechanical Ventilation

STUDY OBJECTIVES

Implementation of new ventilatory strategies such as lung-protective ventilation for ARDS will require a multidisciplinary approach with considerable physician and respiratory therapy (RT) interaction. One of the key factors in this communication is complete and accurate RT documentation of ventilator settings. Few studies have explored the quality and variability of this documentation.

DESIGN

Population-based cross-sectional study.

SETTING

Seventeen adult hospitals in King County, WA.

PARTICIPANTS/INTERVENTIONS

We compared the blank RT ICU flow sheet for each institution to the 1992 American Association for Respiratory Care (AARC) clinical practice guidelines (CPGs) for patient-ventilator system checks. We interviewed RT managers at each hospital about their practices. Finally, we reviewed selected charts of patients with acute lung injury (ALI) or ARDS from each hospital to evaluate the documentation.

MEASUREMENTS/RESULTS

We found substantial variability in RT documentation practices and in their extent of compliance with the AARC CPGs. Only 15 of 52 items recommended by the AARC CPGs were included on blank RT flow sheets of every hospital in our study, and only 26 of 52 items were found on charts of ALI/ARDS patients at most hospitals (ie, > or =10 of 17 hospitals). Only 10 of 17 RT department managers reported using the AARC CPGs as a basis for their documentation policies. Items necessary for the implementation of lung-protective ventilation for ALI/ARDS patients were recorded inconsistently and were not included in the AARC CPGs. Plateau pressure was found on all reviewed charts of ALI/ARDS patients at only 10 of 17 hospitals.

CONCLUSIONS

Considerable variability exists in RT documentation practices. We suggest that new guidelines be developed for documenting the care of patients receiving mechanical ventilation, in light of recent data on ventilator weaning and the management of ALI/ARDS, and that their effect on practice and outcomes be evaluated.

The role of Asp42 in Escherichia coli inorganic pyrophosphatase functioning

Excess of Mg2+ ions is known to inhibit the soluble inorganic pyrophosphatases (PPases). In contrast, the mutant Escherichia coli inorganic pyrophosphatase Asp42-->Asn is three times more active than native and retains its activity at high Mg2+ concentration. In this paper, another two mutant variants with Asp42 replaced by Ala or Glu were investigated to characterize the role of Asp42 in catalysis. pH-independent kinetic parameters of MgPPi hydrolysis and the dissociation constants for the activating and inhibitory Mg2+ ions were calculated. It was shown that Mg2+ inhibition of MgPPi hydrolysis by native PPase exhibited uncompetitive kinetics under the saturating substrate concentration. All three substitutions of Asp42 lead to a sharp decrease of inhibitory Mg2+ affinity to the enzyme. These findings allow determination of the sites of inhibitory and substrate Mg2+ ions binding to PPase. Common features of these mutants allow the conclusion that the function of Asp42 is to accurately coordinate the residues implicated in the substrate and the inhibitory Mg2+ ion binding to PPase active site. Structural analysis of PPase complexed with Mg2+ compared with PPase complexed with Mn2+ and reaction products confirms this supposition.

Molecular dynamics simulation of the antimicrobial salivary peptide histatin-5 in water and in trifluoroethanol: a microscopic description of the water destructuring effect

The results of 520 ps molecular dynamics simulation of histatin-5, a small peptide present in human saliva and possessing antimicrobial activity, dissolved in water and in 2,2,2-trifluoroethanol, are reported. The simulations indicate that histatin-5 is destabilized in water and begins to unfold after 250 ps, while in organic solvent it maintains a regular secondary structure throughout the trajectory. Analysis of the peptide-solvent hydrogen bonds indicates that 2,2,2-trifluoroethanol is a poorer proton acceptor than water. The fluorine atom of the alcohol is almost never engaged in a hydrogen bond and the organic solvent interacts mainly with the peptide through its hydroxyl group. For some residues analysis of the solvent residence time indicated longer values for 2,2,2-trifluoroethanol than for water. The most striking difference is related to the number of times the solvent enters and leaves the first coordination shell of the peptide. This value was more than one order of magnitude higher for water than for the alcohol, suggesting that this may be the main cause of alpha-helix destabilization perpetrated by water.

Structure and characterization of the glycan moiety of L-amino-acid oxidase from the Malayan pit viper Calloselasma rhodostoma

Ophidian L-amino-acid oxidase (L-amino-acid oxygen:oxidoreductase, deaminating, EC 1.4.3.2) is found in the venom of many poisonous snakes (crotalids, elapids and viperids). This FAD-dependent glycoprotein has been studied from several snake species (e.g. Crotalus adamanteus, Crotalus atrox and Calloselasma rhodostoma) in detail with regard to the biochemical and enzymatic properties. The nature of glycosylation, however, as well as the chemical structure(s) of the attached oligosaccharide(s) are unknown. In view of the putative involvement of the glycan moiety in the biological effects of ophidian L-amino-acid oxidase, notably the apoptotic activity of the enzyme, structural knowledge is needed to evaluate its exact function. In this study we report on the glycosylation of L-amino-acid oxidase from the venom of the Malayan pit viper (Calloselasma rhodostoma). Its glycosylation is remarkably homogeneous with the major oligosaccharide accounting for approximately 90% of the total sugar content. Based on detailed analysis of the isolated oligosaccharide by 2D NMR spectroscopies and MALDI-TOF mass spectrometry the glycan is identified as a bis-sialylated, biantennary, core-fucosylated dodecasaccharide. The biological significance of this finding is discussed in light of the biological activities of the enzyme.

Complex of Burkholderia cepacia lipase with transition state analogue of 1-phenoxy-2-acetoxybutane: biocatalytic, structural and modelling study

In a series of four racemic phenoxyalkyl-alkyl carbinols, 1-phenoxy-2-hydroxybutane (1) is enantioselectively acetylated by Burkholderia cepacia (formerly Pseudomonas cepacia) lipase with an E value > or = 200, whereas for the other three racemates E was found to be < or = 4. To explain the high preference of B. cepacia lipase for (R)-(+)-1, a precursor of its transition state analogue with a tetrahedral P-atom, (R(P),S(P))-O-(2R)-(1-phenoxybut-2-yl)methylphosphonic acid chloride was prepared and crystallized in complex with B. cepacia lipase. The X-ray structure of the complex was determined, allowing to compare the conformation of the inhibitor with results of molecular modelling.

AAA+ superfamily ATPases: common structure--diverse function

The AAA+ superfamily of ATPases, which contain a homologous ATPase module, are found in all kingdoms of living organisms where they participate in diverse cellular processes including membrane fusion, proteolysis and DNA replication. Recent structural studies have revealed that they usually form ring-shaped oligomers, which are crucial for their ATPase activities and mechanisms of action. These ring-shaped oligomeric complexes are versatile in their mode of action, which collectively seem to involve some form of disruption of molecular or macromolecular structure; unfolding of proteins, disassembly of protein complexes, unwinding of DNA, or alteration of the state of DNA-protein complexes. Thus, the AAA+ proteins represent a novel type of molecular chaperone. Comparative analyses have also revealed significant similarities and differences in structure and molecular mechanism between AAA+ ATPases and other ring-shaped ATPases.

Crystal structure of Fab198, an efficient protector of the acetylcholine receptor against myasthenogenic antibodies

The crystal structure of the Fab fragment of the rat monoclonal antibody 198, with protective activity for the main immunogenic region of the human muscle acetylcholine receptor against the destructive action of myasthenic antibodies, has been determined and refined to 2.8 A resolution by X-ray crystallographic methods. The mouse anti-lysozyme Fab D1.3 was used as a search model in molecular replacement with the AMORE software. The complementarity determining regions (CDR)-L2, CDR-H1 and CDR-H2 belong to canonical groups. Loops CDR-L3, CDR-H2 and CDR-H3, which seem to make a major contribution to binding, were analyzed and residues of potential importance for antigen-binding are examined. The antigen-binding site was found to be a long crescent-shaped crevice. The structure should serve as a model in the rational design of very high affinity humanized mutants of Fab198, appropriate for therapeutic approaches in the model autoimmune disease myasthenia gravis.