Towards Harmonisation of Critical Laboratory Result Management - Review of the Literature and Survey of Australasian Practices

Timely release and communication of critical test results may have significant impact on medical decisions and subsequent patient outcomes. Laboratories therefore have an important responsibility and contribution to patient safety. Certification, accreditation and regulatory bodies also require that laboratories follow procedures to ensure patient safety, but there is limited guidance on best practices. In Australasia, no specific requirements exist in this area and critical result reporting practices have been demonstrated to be heterogeneous worldwide.Recognising the need for agreed standards and critical limits, the AACB started a quality initiative to harmonise critical result management throughout Australasia. The first step toward harmonisation is to understand current laboratory practices. Fifty eight Australasian laboratories responded to a survey and 36 laboratories shared their critical limits. Findings from this survey are compared to international practices reviewed in various surveys conducted elsewhere. For the successful operation of a critical result management system, critical tests and critical limits must be defined in collaboration with clinicians. Reporting procedures must include how critical results are identified; who can report and who can receive critical results; what is an acceptable timeframe within which results must be delivered or, if reporting fails, what escalation procedures should follow; what communication channels or systems should be used; what should be recorded and how; and how critical result procedures should be maintained and evaluated to assess impact on outcomes.In this paper we review the literature of current standards and recommendations for critical result management. Key elements of critical result reporting are discussed in view of the findings of various national surveys on existing laboratory practices, including data from our own survey in Australasia. Best practice recommendations are made that laboratories are expected to follow in order to provide high quality and safe service to patients.     

Functional Expression of Rat Nav1.6 Voltage-Gated Sodium Channels in HEK293 Cells: Modulation by the Auxiliary β1 Subunit

The Na_v1.6 voltage-gated sodium channel α subunit isoform is abundantly expressed in the adult rat brain. To assess the functional modulation of Na_v1.6 channels by the auxiliary β1 subunit we expressed the rat Na_v1.6 sodium channel α subunit by stable transformation in HEK293 cells either alone or in combination with the rat β1 subunit and assessed the properties of the reconstituted channels by recording sodium currents using the whole-cell patch clamp technique. Coexpression with the β1 subunit accelerated the inactivation of sodium currents and shifted the voltage dependence of channel activation and steady-state fast inactivation by approximately 5–7 mV in the direction of depolarization. By contrast the β1 subunit had no effect on the stability of sodium currents following repeated depolarizations at high frequencies. Our results define modulatory effects of the β1 subunit on the properties of rat Na_v1.6-mediated sodium currents reconstituted in HEK293 cells that differ from effects measured previously in the Xenopus oocyte expression system. We also identify differences in the kinetic and gating properties of the rat Na_v1.6 channel expressed in the absence of the β1 subunit compared to the properties of the orthologous mouse and human channels expressed in this system.     

Cyclo(l-Pro-d-Arg): a new antibacterial and antitumour diketopiperazine from Bacillus cereus associated with a rhabditid entomopathogenic

In continuation of our search for new antimicrobial secondary metabolites from Bacillus cereus associated with rhabditid entomopathogenic nematode, a new microbial diketopiperazine, cyclo(l-Pro-d-Arg), was isolated from the ethyl acetate extract of fermented modified nutrient broth. The chemical structures of the isolated compounds were identified based on their 1D, 2D NMR and high-resolution electrospray ionisation–mass spectroscopy data. Antibacterial activity of the compound was determined by minimum inhibitory concentration and disc diffusion method against medically important bacteria, and the compound was recorded to have significant antibacterial activity against test bacteria. The highest activity was recorded against Klebsiella pneumoniae (1 μg/mL). Cyclo(l-Pro-d-Arg) was recorded to have significant antitumor activity against HeLa cells (IC₅₀ value 50 μg/mL), and this compound was recorded to have no cytotoxicity against normal monkey kidney cells (VERO) up to 100 μg/mL). To the best of our knowledge, this is the first time that cyclo(l-Pro-d-Arg) has been isolated from a microbial natural source.     

C群脑膜炎球菌多糖纯化方法的改进

将C群脑膜炎球菌粗多糖的纯化改进为用1:1容量冷酚提取的生产工艺。结果表明,改进后的方法去除蛋白质效果同样能够达到《中国药典》2005版(三部)的要求,总体结果优于改进前。同时能扩大处理量而降低了生产成本,适合规模化生产。     

Genetic elements associated with antimicrobial resistance in enteropathogenic <Emphasis Type="Italic">Escherichia coli</Emphasis> (EPEC) from Brazil

Background  

We recently observed an association of resistance with a certain enteropathogenic Escherichia coli (EPEC) serotypes and identified a conjugative plasmid, similar to plasmid pED208, that was conserved among archival O111:H2/NM and O119:H2 strains of diverse geographical origin. In this study, we sought to determine the prevalence and distribution of this plasmid among a collection of EPEC isolates from Brazil, as well as to study the susceptibilities of these isolates to antimicrobial agents.     

Effects of delayed freezing on content of phosphagens in human skeletal muscle biopsy samples

The concentrations of ATP, phosphocreatine (PCr), creatine, and lactate were determined in muscle biopsy samples frozen immediately or after a delay of 1-6 min. During the delay the samples were exposed to normal air or a gas mixture of 6.5% CO2-93.5% O2. The ATP content was unchanged, but PCr increased significantly from 72 mmol after rapid freezing to 85 mmol X kg dry muscle-1 during the 1st min in air. The lactate concentration increased (2.8 to 5.2 mmol X kg-1). If muscles were made anoxic by circulatory occlusion for 4-6 min before sampling, no increase in PCr was observed. Direct homogenization of fresh tissue in perchloric acid gave the same ATP, PCr, and lactate contents as frozen samples. It is concluded that the ATP and PCr contents in muscle are unaffected by freezing but that the biopsy procedure activates the energy utilization processes resulting in PCr decrease. It is suggested that the muscle PCr content after a 1-min delay in tissue freezing corresponds to the level in resting fresh muscle.     

Molecular evolution of olfactomedin

Olfactomedin is a secreted polymeric glycoprotein of unknown function, originally discovered at the mucociliary surface of the amphibian olfactory neuroepithelium and subsequently found throughout the mammalian brain. As a first step toward elucidating the function of olfactomedin, its phylogenetic history was examined to identify conserved structural motifs. Such conserved motifs may have functional significance and provide targets for future mutagenesis studies aimed at establishing the function of this protein. Previous studies revealed 33% amino acid sequence identity between rat and frog olfactomedins in their carboxyl terminal segments. Further analysis, however, reveals more extensive homologies throughout the molecule. Despite significant sequence divergence, cysteines essential for homopolymer formation such as the CXC motif near the amino terminus are conserved, as is the characteristic glycosylation pattern, suggesting that these posttranslational modifications are essential for function. Furthermore, evolutionary analysis of a region of 53 amino acids of fish, frog, rat, mouse, and human olfactomedins indicates that an ancestral olfactomedin gene arose before the evolution of terrestrial vertebrates and evolved independently in teleost, amphibian, and mammalian lineages. Indeed, a distant olfactomedin homolog was identified in Caenorhabditis elegans. Although the amino acid sequence of this invertebrate protein is longer and highly divergent compared with its vertebrate homologs, the protein from C. elegans shows remarkable similarities in terms of conserved motifs and posttranslational modification sites. Six universally conserved motifs were identified, and five of these are clustered in the carboxyl terminal half of the protein. Sequence comparisons indicate that evolution of the N-terminal half of the molecule involved extensive insertions and deletions; the C-terminal segment evolved mostly through point mutations, at least during vertebrate evolution. The widespread occurrence of olfactomedin among vertebrates and invertebrates underscores the notion that this protein has a function of universal importance. Furthermore, extensive modification of its N-terminal half and the acquisition of a C-terminal SDEL endoplasmic-reticulum- targeting sequence may have enabled olfactomedin to adopt new functions in the mammalian central nervous system.      

Prolonged exposure to GABA activates GABA-gated chloride channels in the presence of channel-blocking convulsants.

1. In assays of 36Cl- uptake into mouse brain vesicles, 100 microM GABA markedly increased both the initial rate of 36Cl- uptake and the total amount of chloride taken up over a 120-sec incubation period. Specific GABA-dependent 36Cl- uptake (the difference between total and background uptake) was essentially complete within 15 sec of incubation. 2. Incubation with GABA following preincubation with 10 microM endrin, a polychlorocycloalkane insecticide and established blocker of GABA-gated chloride channels, showed a stimulation of uptake over background levels that was much slower in onset than that observed with GABA alone but nevertheless achieved virtually the same level of stimulation above background levels after 90 sec of incubation with GABA. 3. In electrophysiological assays of GABA receptors expressed in Xenopus oocytes following injection with rat brain mRNA, endrin (20 microM) effectively blocked the transient currents elicited by brief exposure of oocytes to GABA (200 microM). However, prolonged exposure to GABA in the absence of perfusion produced a large, slowly-developing inward current. 4. The actions of several known GABA antagonists were also compared as inhibitors of GABA-dependent 36Cl- uptake into mouse brain vesicles at short (4 sec) and long (120 sec) incubation times using concentrations of inhibitors known to produce approximately 70-90% inhibition of GABA-dependent chloride uptake in 4-sec incubations. Picrotoxinin and TBPS, like endrin, were completely ineffective as inhibitors in 120-sec incubations. In contrast, bicuculline was almost as effective at 120 sec as at 4 sec, and avermectin Bla produced approximately 50% inhibition of the GABA response after 120 sec.(ABSTRACT TRUNCATED AT 250 WORDS)