Angela Dawson

Transposition of the Drosophila element mariner into the chicken germ line

The ability of the Drosophila transposable element mariner to transpose in the chicken was tested using a plasmid carrying an active mariner element injected into chick zygotes. Surviving embryos and chicks were analyzed for presence of mariner. Analysis of embryos that survived for at least 12 days of development indicated that mariner had transposed at high frequency into the chicken genome. Germline transmission of mariner from one of three surviving birds confirmed transposition. Analysis of the first-generation (G1) chicks showed that they each contained between one and three copies of mariner. Six different transposition events were represented in the G1 birds, and the transposition was catalyzed by expression of the mariner elements transposase gene. Transmission from G1 to G2 occurred at a 1:1 ratio. Mariner therefore has potential for development as a vector for transgenesis in avian species.

Mechanism of Mos1 transposition: insights from structural analysis.

We present the crystal structure of the catalytic domain of Mos1 transposase, a member of the Tc1/mariner family of transposases. The structure comprises an RNase H‐like core, bringing together an aspartic acid triad to form the active site, capped by N‐ and C‐terminal α‐helices. We have solved structures with either one Mg2+ or two Mn2+ ions in the active site, consistent with a two‐metal mechanism for catalysis. The lack of hairpin‐stabilizing structural motifs is consistent with the absence of a hairpin intermediate in Mos1 excision. We have built a model for the DNA‐binding domain of Mos1 transposase, based on the structure of the bipartite DNA‐binding domain of Tc3 transposase. Combining this with the crystal structure of the catalytic domain provides a model for the paired‐end complex formed between a dimer of Mos1 transposase and inverted repeat DNA. The implications for the mechanisms of first and second strand cleavage are discussed.

Excision of the Drosophila mariner transposon Mos1: Comparison with bacterial transposition and V(D)J recombination

It has been proposed that the modern immune system has evolved from a transposon in an ancient vertebrate. While much is known about the mechanism by which bacterial transposable elements catalyze double-strand breaks at their ends, less is known about how eukaryotic transposable elements carry out these reactions. We have examined the mechanism by which mariner, a eukaryotic transposable element, performs DNA cleavage. We show that the nontransferred strand is cleaved initially, unlike prokaryotic transposons which cleave the transferred strand first. First strand cleavage is not tightly coupled to second strand cleavage and can occur independently of synapsis, as happens in V(D)J recombination but not in transposition of prokaryotic transposons. Unlike V(D)J recombination, however, second strand cleavage of mariner does not occur via a hairpin intermediate.

A LINE-like transposable element in Drosophila, the I factor, encodes a protein with properties similar to those of retroviral nucleocapsids.

I factors are members of the LINE‐like family of transposable elements and move by reverse transcription of an RNA intermediate. Complete I factors contain two open reading frames. The amino acid sequence encoded by the first of these, ORF1, includes the motif CX2CX4HX4C that is characteristic of the nucleocapsid domain of retroviral gag polypeptides followed by a copy of the slightly different sequences CX2CX4HX6C and CX2CX9HX6C. The function of this protein is unknown. We have expressed this protein in Escherichia coli and Spodoptera frugiperda cells and have shown that it binds both DNA and RNA but without any evidence for sequence specificity. The properties of deletion derivatives of the protein indicate that more than one region is responsible for DNA binding and that the CCHC motif is not essential for this. The ORF1 protein expressed in either E.coli or Spodoptera cells forms high molecular weight structures that require the region of the protein including the CCHC motif for their formation. This protein can also accelerate the annealing of complementary single‐stranded oligonucleotides. These results suggest that this protein may associate with the RNA transposition intermediates of the I factor to form particles that enter the nucleus during transposition and that it may stimulate both the priming of reverse transcription and integration. This may be generally true for the product of the first open reading frame of LINE‐like elements.

Swimming in a crystal

We study catalytic Janus particles and Escherichia coli bacteria swimming in a two-dimensional colloidal crystal. The Janus particles orbit individual colloids and hop between colloids stochastically, with a hopping rate that varies inversely with fuel (hydrogen peroxide) concentration. At high fuel concentration, these orbits are stable for 100s of revolutions, and the orbital speed oscillates periodically as a result of hydrodynamic, and possibly also phoretic, interactions between the swimmer and the six neighbouring colloids. Motile E. coli bacteria behave very differently in the same colloidal crystal: their circular orbits on plain glass are rectified into long, straight runs, because the bacteria are unable to turn corners inside the crystal.

Genes Required for Growth at High Hydrostatic Pressure in Escherichia coli K-12 Identified by Genome-Wide Screening

Despite the fact that much of the global microbial biosphere is believed to exist in high pressure environments, the effects of hydrostatic pressure on microbial physiology remain poorly understood. We use a genome-wide screening approach, combined with a novel high-throughput high-pressure cell culture method, to investigate the effects of hydrostatic pressure on microbial physiology in vivo. The Keio collection of single-gene deletion mutants in Escherichia coli K-12 was screened for growth at a range of pressures from 0.1 MPa to 60 MPa. This led to the identification of 6 genes, rodZ, holC, priA, dnaT, dedD and tatC, whose products were required for growth at 30 MPa and a further 3 genes, tolB, rffT and iscS, whose products were required for growth at 40 MPa. Our results support the view that the effects of pressure on cell physiology are pleiotropic, with DNA replication, cell division, the cytoskeleton and cell envelope physiology all being potential failure points for cell physiology during growth at elevated pressure.

Exploring the DNA mimicry of the Ocr protein of phage T7

DNA mimic proteins have evolved to control DNA-binding proteins by competing with the target DNA for binding to the protein. The Ocr protein of bacteriophage T7 is the most studied DNA mimic and functions to block the DNA-binding groove of Type I DNA restriction/modification enzymes. This binding prevents the enzyme from cleaving invading phage DNA. Each 116 amino acid monomer of the Ocr dimer has an unusual amino acid composition with 34 negatively charged side chains but only 6 positively charged side chains. Extensive mutagenesis of the charges of Ocr revealed a regression of Ocr activity from wild-type activity to partial activity then to variants inactive in antirestriction but deleterious for cell viability and lastly to totally inactive variants with no deleterious effect on cell viability. Throughout the mutagenesis the Ocr mutant proteins retained their folding. Our results show that the extreme bias in charged amino acids is not necessary for antirestriction activity but that less charged variants can affect cell viability by leading to restriction proficient but modification deficient cell phenotypes.

Painting with light-powered bacteria

External control of the swimming speed of ‘active particles’ can be used to self assemble designer structures in situ on the μm to mm scale. We demonstrate such reconfigurable templated active self assembly in a fluid environment using light powered strains of Escherichia coli. The physics and biology controlling the sharpness and formation speed of patterns is investigated using a bespoke fast-responding strain. Microand nano-fabrication can revolutionise many areas of technology, including personalised medicine. There are two conceptually distinct ways to construct structures on the 10 nm to 10 μm scale: lithography, which uses ‘scalpels’ such as chemical etching or electron beams, or self assembly[1], in which microscopic ‘Lego components’ move themselves into position. Both equilibrium phase transitions (e.g. crystallization) and nonequilibrium processes are exploited for self assembly. In either case, external templates can be used to direct the process, with reconfigurable templates offering programmability. Self assembly was originally inspired by chemistry and biology, where the components are individual molecules. Increasingly, colloidal building blocks are used, with bespoke particle shape, size and interaction, e.g. ‘patchy particles’ with heterogeneous surface chemistry[2]. Active, or self-propelled, colloids open up further opportunities. We show how to assemble structures on the μm to mm scale that are reconfigurable in real time using Escherichia coli bacteria – ‘living active colloids’ – that swim only when illuminated[3]. The process is directed by a smart, or programmable, external template applied by a spatial light modulator. Active colloids, or self-propelled micro-swimmers, are attracting significant recent attention[4] as ‘active matter’[5, 6]. They violate time-reversal symmetry[7], and may be used, e.g., to transport colloidal ‘cargos’[8]. For both fundamental physics and applications, external control of swimming, e.g. using particles with lightactivated self-propulsion[9, 10, 11, 12], opens up many new possibilities. Thus, e.g., light-activated motile bacteria can be used to actuate and control micro-machinery [13]. ∗Electronic address: j.arlt@ed.ac.uk; Corresponding author 1 ar X iv :1 71 0. 08 18 8v 1 [ co nd -m at .s of t] 2 3 O ct 2 01 7 The self assembly of micro-swimmers into clusters of tens of particles has already been demonstrated[14, 15, 12]. Recent simulations[16] suggest that the patterned illumination of light-activated swimmers can be used for the templated self assembly[1] of designer structures comprising 10-10 particles. Real-time reconfiguration of the light field then allows smart templated active self assembly (STASA), which we here implement for the first time using light-controlled motile bacteria. E. coli bacteria[17] (cell body ≈ 2 μm×1 μm) swim by turning ≈ 7-10 μm long helical flagella using membraneembedded rotary motors powered by a protonmotive force (PMF) that arises from active pumping of H to the extracellular medium[18]. Unlike all synthetic active colloids to date and most bacteria, E. coli can generate PMF in nutrient-free motility buffer[19] by utilising internal resources and oxygen (O2) to produce energetic electron pairs. These release their energy stepwise along an electrochemical potential ladder of respiratory enzymes located in the inner cell membrane, generating a PMF of ≈ −150 mV. The electron pair ultimately passes to and reduces O2 to water. Thus, with no O2, PMF = 0 and swimming ceases[17]. If cells under anaerobic conditions can express proteorhodopsin (PR)[3], a green-photon-driven proton pump[20], then they will swim only when suitably illuminated: these are living analogues of synthetic light-activated colloidal swimmers.[9, 10, 11, 12] We show below that the speed with which such cells respond to changes in illumination is crucial for successful bacterial STASA. For this work, we constructed a PR-bearing mutant (AD10) that stops much faster when illumination ceases than previously-reported[3, 21], by deleting the unc gene cluster[22] encoding the F1FoATPase membrane protein complex (see SI §1.1), so that these enzymes cannot act in reverse in darkness to continue to export protons and sustain a PMF[23]. We suspended cells in phosphate motility buffer at optical density OD . 8 (cell-body volume fraction ≈ 1.1%)[17] and sealed 2 μL into 20 μm high flat capillaries, where cells swim in two dimensions but have enough room to ‘overtake’ each other in all three spatial dimensions. Differential dynamic microscopy (DDM)[24] returned an averaged speed v̄ ≈ 30 μm s−1 and β ≈ 20% of non-motile organisms at OD=1 under fully-oxygenated conditions. (Note that ‘non-motile’ = cells that can never swim; ‘stationary’ = non-swimming cells capable of motility when illuminated.) Motile cells were allowed to swim until O2 was depleted and v̄ dropped abruptly to zero after a few minutes[17] (see SI §1.2 and Fig. S1(a)). After these cells were left in the dark for ≈ 10 min, green illumination was turned on (510 – 560 nm, intensity I ≈ 5 mW cm−2 at the sample). The stationary cells accelerated uniformly before saturating, Fig. 1. Fitting the data to v̄(t) = v̄satt/(t+τon) gives v̄sat = 9.5 μm s−1, τon = 30 s. When illumination ceased, v̄ dropped within τoff . 1 s, but never quite to zero – it is unclear why a few cells (< 1%) continued to swim. v̄sat increased with I, Fig. 1 (inset), up to . 27 μm s−1. {v̄, β, vsat, τon} changed over hours as cells aged. The discharging of the PMF through the membrane (capacitance C & 10−14 F) and rotary motors (total resistance R . 10 Ω) upon cessation of illumination should take RC ∼ 1 s (see SI §1.3 for details), which explains the observed τoff . Consistent with this interpretation, τoff is approximately independent of the starting speed of decelerating cells (see SI §1.2 and Fig. S2(a)). The observed τon ≈ 30 s is likely controlled by the rate constant[25] for stator units to come on and off motors, kstator ≈ 0.04 s−1 ∼ τ−1 on . In sustained darkness, motors disassemble in PR-bearing E. coli, and full ‘motor resurrection’ upon illumination takes[21] ∼ 200 s, in agreementSelf-assembly is a promising route for micro- and nano-fabrication with potential to revolutionise many areas of technology, including personalised medicine. Here we demonstrate that external control of the swimming speed of microswimmers can be used to self assemble reconfigurable designer structures in situ. We implement such ‘smart templated active self assembly’ in a fluid environment by using spatially patterned light fields to control photon-powered strains of motile Escherichia coli bacteria. The physics and biology governing the sharpness and formation speed of patterns is investigated using a bespoke strain designed to respond quickly to changes in light intensity. Our protocol provides a distinct paradigm for self-assembly of structures on the 10 μm to mm scale.The ability to generate microscale patterns and control microswimmers may be useful for engineering smart materials. Here Arlt et al. use genetically modified bacteria with fast response to changes in light intensity to produce light-induced patterns.

A Randomised Controlled Trial of High-Dose Immunosuppression in Paraquat Poisoning

Objective: To survey the availability of antidotes in acute hospitals in the United Kingdom following the publication of joint College of Emergency Medicine and National Poisons Information Service guidelines on antidote stocking in 2008. Methods: A questionnaire was sent to the Chief Pharmacist in 224 hospitals with emergency departments in the UK in July 2010 requesting information on the availability of 28 antidotes categorised in 3 groups: available immediately (category A), available within 1 hour (category B) and available supra-regionally (category C). Results: Completed questionnaires were received from 196 (87.5%) of the 224 hospitals by the survey completion date of 31st January 2011. In the category A list of antidotes, commonly used antidotes such as acetylcysteine, activated charcoal, naloxone, fl umazenil were available for immediate use in more than 90% of hospitals surveyed but the availability of cyanide antidotes was much lower. Dicobalt edetate, currently recommended as the antidote of choice for severe confi rmed cyanide poisoning, was available immediately in 144 (74%) and was not stocked in 29 (15%) hospitals. Hydroxocobalamin, sodium nitrite and sodium thiosulphate were available for immediate use in 21%, 57% and 66% of hospitals respectively. In the category B list, dantrolene, desferrioxamine and phytomenadione (vitamin K) were available for use within 1 hour in more than 90% of hospitals but there was poor availability of cyproheptadine (45%), viper venom antiserum (45%), pralidoxime (30%) and antidotes used for the treatment of toxic alcohol poisoning, with intravenous ethanol being available within 1 hour in 72%, oral ethanol in 28% and fomepizole in 18% of hospitals. Antidotes which are rarely used and recommended for supra-regional stocking were stocked in few hospitals, ranging from 4% for DMSA and DMPS, 20% for botulinum antitoxin and 25% for sodium calcium edetate. Conclusion: Commonly indicated antidotes are widely available but there is inconsistent stocking of less commonly used antidotes, for example those used to treat poisoning with organophosphorus insecticides, cyanide and toxic alcohols. This is of concern because these agents are frequently associated with severe morbidity and mortality and the timely use of an appropriate antidote may be life-saving in these situations.Objective: The indications for, and availability of, laboratory assays required for the effective management of the poisoned patient are described. Methods: Currently recommended assays, their indications and their availability were reviewed within the United Kingdom by the National Poisons Information Service and the Association for Clinical Biochemistry. Results: Laboratory assays for toxins and/or their metabolites are a very important part of the management of patients with potentially serious poisoning. However, there is evidence that laboratory toxicological investigations are overused by medical staff. There is also evidence that the availability of these investigations varies between hospitals, particularly when required outside normal working hours. This may present problems in management. Indications for laboratory assays include: confi rmation of the diagnosis of poisoning when this is in doubt; to infl uence patient management, (e.g. the need for further investigations, antidotes, haemodialysis or other extracorporeal methods of elimination, or to stop treatment) and to plan the re-institution of chronic therapy. They are also of use in the diagnosis of brain death, in assessing the suitability of potential organ donors and for medico-legal or forensic reasons. In addition to supportive investigations which are widely available (e.g. urea and electrolytes, glucose, calcium, magnesium, creatine kinase, liver function tests, clotting studies, anion gap, osmolarity, blood gas analysis), specialist assays should be available at hospitals admitting acutely poisoned patients. These specifi c assays may be divided into two groups. Group 1 should be available on a 24 hour basis in all hospitals that admit patients with acute poisoning (Table 1). Group 2 includes those assays that are important in patient management but which are infrequently needed (Table 1). For these, arrangements need to be in place so that the assays can be obtained from specialist laboratories if they are not available on site. This may involve an arrangement with a supra-regional specialist toxicology laboratory or a subregional centre. It is the responsibility of each individual hospital to ensure that appropriate arrangements are in place and that staff can follow these arrangements when the need arises, including outside normal working hours. Laboratory staff should have contact details readily available for specialist laboratories providing these assays, together with information on how samples should be collected and transported. Clinical staff should discuss the use of group two assays with a local clinical biochemist and consider seeking advice from a Poisons Information Centre. In a national survey of major hospitals in the United Kingdom, most Group 1 assays were available at all times. However, this was not the case for Group 2 assays. In this group assays for pharmaceuticals were more readily available than other assays: in particular, the availability of assays for cholinesterase, cyanide and heavy metals was poor. It is essential to be aware of the type of sample required and the units in which results are specifi ed. A consensus meeting held by the Association for Clinical Biochemists agreed that concentrations for drugs should be reported in mass units per litre with the exception of iron, lithium, methotrexate and thyroxine. To avoid confusion it is recommended that, with the exception of these four agents, laboratories that report in molar units should also provide the result in mass units and should be encouraged for patient safety reasons to adopt the recommended use of mass units. Reference: 1. National Poisons Information Service; Association of Clinical Biochemists. Laboratory analyses for poisoned patients: joint position paper. Ann Clin Biochem 2002; 39:328 – 39.Objective: ‘ Steatoda nobilis ’ , commonly known as the false black widow spider, is an immigrant spider originating from the Canary Islands. Closely related to the black widow species but lacking its distinctive red spot, this spider was fi rst reported in the UK in 1879. It has since become acclimatised along the south coast of England although National Poisons Information Service (NPIS) call records indicate that it has been witnessed as far north as Yorkshire. While the spider is not considered aggressive, it possesses large venomous fangs that can instigate ‘ instant ’ severe pain, described as being worse than a wasp sting. Methods: A case study is reported and enquiries to NPIS concerning false black widow spider bites between August 2007 and August 2011 were analysed with regard to location and features. Case report: A 41-year-old male presented to the accident and emergency department two days after being bitten on the calf by a spider subsequently identifi ed as ‘ Steatoda nobilis ’ . He was treated prophylactically with co-amoxiclav. The skin around the bite was warm and discoloured with acute swelling at the puncture site. NPIS advised that apart from appropriate analgesia further treatment was unlikely to be required and that localised features from the envenomation would subside with time. Other than mild cellulitis in the calf and a raised CRP (31 mg/L), this patient exhibited no systemic complications and was discharged the same day. Results: NPIS received 21 enquiries involving ‘ Steatoda nobilis ’ throughout the study period. The majority of enquiries were from southern England with a few as far north as Yorkshire and Suffolk. Localised oedema was the most signifi cant feature along with hypoaesthesia, paraesthesia and skin rash. Systemic features such as tachycardia, chest tightness, vomiting, anxiety with increased sweating and fever were also reported in fi ve cases. Conclusion: It has been reported that ‘ Steatoda nobilis ’ bites may be neurotoxic and affect the parasympathetic nervous system. 1 Nevertheless, NPIS experience suggests that these bites, although sometimes medically signifi cant, can be managed successfully with supportive care and analgesia. Reference: 1. Warrell DA, Shaheen J, Hillyard PD, et al. Neurotoxic envenoming by an immigrant spider (Steatoda Nobilis) in southern England. Toxicon 1991; 29:1263 – 5.Objective: Prescription stimulant abuse is on the rise in the United States (US). Abuse in other countries is not well studied. The objective of this study is to characterize human exposures to specifi c prescription stimulants reported to poison centres from multiple countries over a four year study period. Methods: Human exposures to methylphenidate and amfetamines reported to poison centres from 2007 – 2010 were obtained using a standardized data template with written defi nitions. Rates are reported as number of exposures reported to poison centre per 100,000 population. Results: Seven countries participated; Australia, Germany (G o ttingen), Italy, Netherlands, Switzerland, United Kingdom (UK) and US. All centres manage calls from health care providers. Australia, Italy, Germany, Switzerland and US manage calls from the public as well. Methylphenidate: Five of 7 countries reported an increase during the study period (range 17 – 137%; Table 1). The UK reported a decrease of 28%. Amfetamine: US reported the highest rate and surpassed second ranked Netherlands by almost 4-fold. While US, Netherlands and Australia reported increased amfetamine rates (range 18 – 221%), the remaining countries suggesting a downward trend from 8 to 45%. There are no prescription amphetamines available in Switzerland. Conclusions: Methylphenidate exposures per person increased in the majority of participating countries. Amfetamine exposures were less commonly reported to participating non-US centres, which indicated less than 50% change during the study period. While these data illustrate rates over time within each country, one cannot compare rates between countries due to variation of data collection methods (some centres accept calls from the public, some do not). Additional data is required on reporting bias, drug availability, drug supply source, and perhaps cultural differences that may contribute to these fi ndings.Objective: Ambulance paramedics, often the fi rst point of contact with poisoned patients, need to make rapid assessments and instigate appropriate emergency treatment plans. To do so effectively they require speedy access to relevant information. This outreach programme was established to ensure that all ambulance personnel in Wales and South West England are familiar with the full range of resources offered by The National Poisons Information Service (NPIS). Methods: All ambulance stations in Wales and the South West (173) were contacted by letter and/or telephone and provided with the following information: 1. General information about NPIS and a request that all ambulance crews be made aware of the NPIS 24/7 poisons enquiry telephone number. 2. Information relating to TOXBASE ® , the primary toxicology database of the NPIS, and an encouragement to each station to apply for free registration. (Telephone number and website information were also provided in the form of stickers and postcards for ease of dissemination and availability to individual crews) 3. NPIS (Cardiff) offers free hands-on training for ambulance personnel in the effi cient use of TOXBASE ® . Consultant clinical toxicologists are also available to provide training in the basic management of poisoned patients including recognition of toxidromes and signs and symptoms relating to the severity of poisoning; training courses often being structured to the specifi c requirements of individual cohorts. Results: Since the outreach programme began, TOXBASE ® registrations from ambulance stations have increased 31% in Wales and 44% in the South West. There has also been a very positive response to the offer of specialist training; overall 217 ambulance personnel have received training from poisons information specialists and clinical toxicologists on the effi cient use of TOXBASE ® and other aspects of poisoning in 13 separate training sessions. Six specialist training sessions have also been held for 42 members of the South West England Hazardous Area Response Team (HART). Conclusion: Specialised training greatly enhances the confi dence of paramedics when dealing with poisoned patients. In cases where there remains uncertainty regarding the potential toxicity of agents, access to TOXBASE ® or the poisons enquiry line provides invaluable reassurance and markedly reduces the costs associated with unnecessary transport and accident and emergency admission.Objective: To investigate the circumstances and etiology of ranitidine overdose in patients aged under 3 years old reported to the UK National Poisons Information Service (NPIS) between November 2008 and October 2011. Disproportionately high levels of therapeutic error have been noted during calls to NPIS centres. The causes of this are investigated. Methods: Using data extracted from UKPID, a centralised NPIS telephone enquiry database, we reviewed the number and nature of incidents involving ranitidine from November 2008 to October 2011. Results: 244 calls were made to the NPIS between 01/11/2008 and 31/10/2011 regarding poisoning with ranitidine alone. One hundred and ninety- six incidents (80.3%) involved children aged under 3 and 205 (84.0%) involved children aged under 5; by contrast, in the fi nancial year 2010 – 2011, only 28.8% of all calls made to the NPIS involved children aged under 5 (p � 0.0001). In those patients aged under 3, 86.7% (170/196) of ranitidine overdoses were due to therapeutic error, compared to 7.0% of all calls for the same age group taken in the same time period (p � 0.0001). Of those patients who overdosed as a result of therapeutic error, 146 (85.9%) ingested ranitidine syrup, and 43 of these patients (29.5%) were given a 10 times overdose of 75 mg/5 mL syrup. Medical intervention was required in 19.4% (38/196) of all patients under 3, most commonly investigations (16/38 or 42.1% of patients). 11/196 patients (5.6%) were referred to A&E and 12/196 patients (6.1%) were referred to their GP. 85.2% (167/196) patients were asymptomatic; 10.2% (20/196) patients had minor features, and 1 patient (0.5%) had moderate features (multiple episodes of vomiting and diarrhoea). Conclusion: Ranitidine overdose is a common enquiry to the NPIS. Although usually asymptomatic these cases often required some sort of medical intervention. Cases frequently involved paediatric patients. Overdose commonly occurred due to administration of 10x the prescribed dose of ranitidine syrup, suggesting a preventable dosing error by carers. Although the consequences of ranitidine overdose are usually benign, these results suggest that formulation changes could reduce risk and prevent unnecessary presentations to health professionals.bearing on the assigned triage category. The existence of poisons information centres (PIC) within a healthcare system has signifi cant implications on emergency triage presentations. 5 The ability to fi lter the majority of trivial and minor exposures with out-of-hospital management selects higher acuity patients for ED presentation. PICs also play a key role in ambulance triage at the scene as well as in ambulance control systems that decide on transportation of potentially poisoned patients. ED triage offi cers may also choose to contact a PIC during or at the completion of triage in order to modify risk stratifi cation. Experienced triage offi cers are able to appropriately triage poisoned patients with symptoms and signs, particularly those involving agents that cause reduced level of consciousness or coma. Diffi culties in triage are more common with the well-looking patient whose toxidrome has yet to develop or does not manifest in altered sensorium, gastrointestinal upset or dyspnoea. Common triage pitfalls include ingestions of cardiac medications, heavy metals, oral hypoglycaemic agents, unusual chemicals, sustained-release preparations and paediatric patients. 6,7 Emergency triage systems, in their current form, do not necessarily take into account a risk assessment of the potential toxicity of the agent ingested. As such, they may fail to predict precipitous clinical deterioration in a minority of cases. Furthermore, failure to recognise potentially severe complications of specifi c agents, such as calcium channel blockers, may delay early life-saving interventional strategies. The triage offi cer has an additional role in instituting decontamination, if appropriate. Conclusion: Emergency triage of the poisoned patient is a crucial decision point in their medical management – ultimately, it can mean the difference between life and death. Several emergency triage systems are utilised around the world, each with its own limitations in risk assessment. The existence of poisons information centres within a healthcare system has signifi cant bearing on ED presentations of poisoning and envenomation. There are uncommon and dangerous toxicological presentations that require an astute and experienced triage offi cer to recognise the potential for life-threatening toxicity. References: 1. Australasian College for Emergency Medicine. The Australasian Triage Scale. www.acem.org.au [accessed 23 Jan 2012]. 2. Mackway-Jones K, Marsden J, Windle J, eds. Emergency Triage. Manchester Triage Group. 2nd ed. Oxford, England: Blackwell Publishing. BMJ Books, 2005. 3. Grouse AI, Bishop RO, Bannon AM. The Manchester Triage System provides good reliability in an Australian emergency department. Emerg Med J 2009; 26:484 –6. 4. Commonwealth of Australia. Emergency Triage Education Kit, 2009. www.health. gov.au [accessed 23 Jan 2012]. 5. Benson BE, Smith CA, McKinney PE, et al. Do poison center triage guidelines affect healthcare facility referrals? J Toxicol Clin Toxicol 2001; 39:433 – 8. 6. Bartlett D. Tricky toxic presentations at triage. J Emerg Nurs 2005; 31:403 – 4. 7. Wolf L. Considerations in triage for the intoxicated patient. J Emerg Nurs 2008; 34:272 – 3. The Role of the ECG in Risk Assessment of the 2. Poisoned Patient Manini AF. Division of Medical Toxicology, Department of Emergency Medicine, Mount Sinai School of Medicine, Elmhurst Hospital Centre, New York, US Background: Poisoning is the leading cause of cardiac arrest in patients under 40 years of age 1 and the second-leading cause of injury-related fatality across all age groups in the US 2 . The ECG represents a rapidly available clinical tool that can help clinicians manage poisoned patients. Specifi c myocardial effects of cardiotoxic drugs have well-described electrocardiographic manifestations. The objectives of this review are: (a) to summarize specifi c toxic effects on the myocardium that can cause characteristic ECG changes; (b) to review the approach to the ECG in acutely poisoned patients and ECG-toxidrome pearls; and (c) to integrate ECG interpretation with management decisions in the poisoned patient. Discussion: Clinicians should adopt a systematic approach to ECG interpretation for poisoned patients that includes analysis of rhythm, intervals (QRS, QT, etc), and ischemic changes (ST and T wave changes). Common patterns of ECG manifestations may serve as pearls to aid clinicians in diagnosis and management of poisoning. In the setting of poisoning, drug classes that cause characteristic ECG manifestations include ion channel antagonists (sodium, potassium, calcium), cardioactive steroids (sodium-potassium ATPase), and beta adrenergic antagonists. Recent data suggests that initial ECG interpretation may predict in-hospital prognosis for patients with undifferentiated poisonings in the emergency department. 3 Poisoned patients suffering from cardiac arrest should be treated according to Advanced Cardiac Life Support (ACLS) guidelines with consideration of toxicology-specifi c antidotes as adjunctive therapy. 4 Conclusion: In medical toxicology, the ECG plays an important role in the evaluation of the poisoned patient to identify or exclude cardiotoxicity, as well as to take fundamental initial steps in initial management. A sound understanding of ECG interpretation and the characteristics of cardiotoxicity is necessary to establish a basis for the utility of the ECG in drug overdose. A systematic approach to the ECG in poisoned patients based on patterns of cardiotoxicity may help clinicians identify management strategies to ameliorate cardiotoxicity. References: 1. ECC Committee, Subcommittees and Task Forces of the American Heart Association. 2005 American Heart Association guidelines for cardiopulmonary resuscitation and emergency cardiovascular care. Circulation C lin ic al T ox ic ol og y D ow nl oa de d fr om in fo rm ah ea lth ca re .c om b y U ni ve rs ity o f Z ue ri ch o n 04 /3 0/ 12 Fo r pe rs on al u se o nl y.

Bacteria as living patchy colloids: Phenotypic heterogeneity in surface adhesion

Genetically identical bacteria possess varying numbers of surface-adhering patches. Understanding and controlling the surface adhesion of pathogenic bacteria is of urgent biomedical importance. However, many aspects of this process remain unclear (for example, microscopic details of the initial adhesion and possible variations between individual cells). Using a new high-throughput method, we identify and follow many single cells within a clonal population of Escherichia coli near a glass surface. We find strong phenotypic heterogeneities: A fraction of the cells remain in the free (planktonic) state, whereas others adhere with an adhesion strength that itself exhibits phenotypic heterogeneity. We explain our observations using a patchy colloid model; cells bind with localized, adhesive patches, and the strength of adhesion is determined by the number of patches: Nonadherers have no patches, weak adherers bind with a single patch only, and strong adherers bind via a single or multiple patches. We discuss possible implications of our results for controlling bacterial adhesion in biomedical and other applications.