Mild and repetitive very mild axonal stretch injury triggers cystoskeletal mislocalization and growth cone collapse

Diffuse axonal injury is a hallmark pathological consequence of non-penetrative traumatic brain injury (TBI) and yet the axonal responses to stretch injury are not fully understood at the cellular level. Here, we investigated the effects of mild (5%), very mild (0.5%) and repetitive very mild (2×0.5%) axonal stretch injury on primary cortical neurons using a recently developed compartmentalized in vitro model. We found that very mild and mild levels of stretch injury resulted in the formation of smaller growth cones at the tips of axons and a significantly higher number of collapsed structures compared to those present in uninjured cultures, when measured at both 24 h and 72 h post injury. Immunocytochemistry studies revealed that at 72 h following mild injury the axonal growth cones had a significantly higher colocalization of βIII tubulin and F-actin and higher percentage of collapsed morphology than those present following a very mild injury. Interestingly, cultures that received a second very mild stretch injury, 24 h after the first insult, had a further increased proportion of growth cone collapse and increased βIII tubulin and F-actin colocalization, compared with a single very mild injury at 72 h PI. In addition, our results demonstrated that microtubule stabilization of axons using brain penetrant Epothilone D (EpoD) (100 nM) resulted in a significant reduction in the number of fragmented axons following mild injury. Collectively, these results suggest that mild and very mild stretch injury to a very localized region of the cortical axon is able to trigger a degenerative response characterized by growth cone collapse and significant abnormal cytoskeletal rearrangement. Furthermore, repetitive very mild stretch injury significantly exacerbated this response. Results suggest that axonal degeneration following stretch injury involves destabilization of the microtubule cytoskeleton and hence treatment with EpoD reduced fragmentation. Together, these results contribute a better understanding of the pathogenesis of mild and repetitive TBI and highlight the therapeutic effect of microtubule targeted drugs on distal part of neurons using a compartmentalized culturing model

Antimicrobial resistance among migrants in Europe: a systematic review and meta-analysis

BACKGROUND: Rates of antimicrobial resistance (AMR) are rising globally and there is concern that increased migration is contributing to the burden of antibiotic resistance in Europe. However, the effect of migration on the burden of AMR in Europe has not yet been comprehensively examined. Therefore, we did a systematic review and meta-analysis to identify and synthesise data for AMR carriage or infection in migrants to Europe to examine differences in patterns of AMR across migrant groups and in different settings. METHODS: For this systematic review and meta-analysis, we searched MEDLINE, Embase, PubMed, and Scopus with no language restrictions from Jan 1, 2000, to Jan 18, 2017, for primary data from observational studies reporting antibacterial resistance in common bacterial pathogens among migrants to 21 European Union-15 and European Economic Area countries. To be eligible for inclusion, studies had to report data on carriage or infection with laboratory-confirmed antibiotic-resistant organisms in migrant populations. We extracted data from eligible studies and assessed quality using piloted, standardised forms. We did not examine drug resistance in tuberculosis and excluded articles solely reporting on this parameter. We also excluded articles in which migrant status was determined by ethnicity, country of birth of participants' parents, or was not defined, and articles in which data were not disaggregated by migrant status. Outcomes were carriage of or infection with antibiotic-resistant organisms. We used random-effects models to calculate the pooled prevalence of each outcome. The study protocol is registered with PROSPERO, number CRD42016043681. FINDINGS: We identified 2274 articles, of which 23 observational studies reporting on antibiotic resistance in 2319 migrants were included. The pooled prevalence of any AMR carriage or AMR infection in migrants was 25·4% (95% CI 19·1-31·8; I2 =98%), including meticillin-resistant Staphylococcus aureus (7·8%, 4·8-10·7; I2 =92%) and antibiotic-resistant Gram-negative bacteria (27·2%, 17·6-36·8; I2 =94%). The pooled prevalence of any AMR carriage or infection was higher in refugees and asylum seekers (33·0%, 18·3-47·6; I2 =98%) than in other migrant groups (6·6%, 1·8-11·3; I2 =92%). The pooled prevalence of antibiotic-resistant organisms was slightly higher in high-migrant community settings (33·1%, 11·1-55·1; I2 =96%) than in migrants in hospitals (24·3%, 16·1-32·6; I2 =98%). We did not find evidence of high rates of transmission of AMR from migrant to host populations. INTERPRETATION: Migrants are exposed to conditions favouring the emergence of drug resistance during transit and in host countries in Europe. Increased antibiotic resistance among refugees and asylum seekers and in high-migrant community settings (such as refugee camps and detention facilities) highlights the need for improved living conditions, access to health care, and initiatives to facilitate detection of and appropriate high-quality treatment for antibiotic-resistant infections during transit and in host countries. Protocols for the prevention and control of infection and for antibiotic surveillance need to be integrated in all aspects of health care, which should be accessible for all migrant groups, and should target determinants of AMR before, during, and after migration. FUNDING: UK National Institute for Health Research Imperial Biomedical Research Centre, Imperial College Healthcare Charity, the Wellcome Trust, and UK National Institute for Health Research Health Protection Research Unit in Healthcare-associated Infections and Antimictobial Resistance at Imperial College London

Surgical site infection after gastrointestinal surgery in high-income, middle-income, and low-income countries: a prospective, international, multicentre cohort study

Background: Surgical site infection (SSI) is one of the most common infections associated with health care, but its importance as a global health priority is not fully understood. We quantified the burden of SSI after gastrointestinal surgery in countries in all parts of the world. Methods: This international, prospective, multicentre cohort study included consecutive patients undergoing elective or emergency gastrointestinal resection within 2-week time periods at any health-care facility in any country. Countries with participating centres were stratified into high-income, middle-income, and low-income groups according to the UN's Human Development Index (HDI). Data variables from the GlobalSurg 1 study and other studies that have been found to affect the likelihood of SSI were entered into risk adjustment models. The primary outcome measure was the 30-day SSI incidence (defined by US Centers for Disease Control and Prevention criteria for superficial and deep incisional SSI). Relationships with explanatory variables were examined using Bayesian multilevel logistic regression models. This trial is registered with ClinicalTrials.gov, number NCT02662231. Findings: Between Jan 4, 2016, and July 31, 2016, 13 265 records were submitted for analysis. 12 539 patients from 343 hospitals in 66 countries were included. 7339 (58·5%) patient were from high-HDI countries (193 hospitals in 30 countries), 3918 (31·2%) patients were from middle-HDI countries (82 hospitals in 18 countries), and 1282 (10·2%) patients were from low-HDI countries (68 hospitals in 18 countries). In total, 1538 (12·3%) patients had SSI within 30 days of surgery. The incidence of SSI varied between countries with high (691 [9·4%] of 7339 patients), middle (549 [14·0%] of 3918 patients), and low (298 [23·2%] of 1282) HDI (p < 0·001). The highest SSI incidence in each HDI group was after dirty surgery (102 [17·8%] of 574 patients in high-HDI countries; 74 [31·4%] of 236 patients in middle-HDI countries; 72 [39·8%] of 181 patients in low-HDI countries). Following risk factor adjustment, patients in low-HDI countries were at greatest risk of SSI (adjusted odds ratio 1·60, 95% credible interval 1·05–2·37; p=0·030). 132 (21·6%) of 610 patients with an SSI and a microbiology culture result had an infection that was resistant to the prophylactic antibiotic used. Resistant infections were detected in 49 (16·6%) of 295 patients in high-HDI countries, in 37 (19·8%) of 187 patients in middle-HDI countries, and in 46 (35·9%) of 128 patients in low-HDI countries (p < 0·001). Interpretation: Countries with a low HDI carry a disproportionately greater burden of SSI than countries with a middle or high HDI and might have higher rates of antibiotic resistance. In view of WHO recommendations on SSI prevention that highlight the absence of high-quality interventional research, urgent, pragmatic, randomised trials based in LMICs are needed to assess measures aiming to reduce this preventable complication

Integrated Microfluidic Devices Fabricated in Poly (Methyl Methacrylate) (PMMA) for On-site Therapeutic Drug Monitoring of Aminoglycosides in Whole Blood

On-site therapeutic drug monitoring (TDM) is important for providing a quick and accurate dosing to patients in order to improve efficacy and minimize toxicity. Aminoglycosides such as amikacin, gentamicin, and tobramycin are important antibiotics that have been commonly used to treat infections of chronic bacterial infections in the urinary tract, lung, and heart. However, these aminoglycosides can lead to vestibular and auditory dysfunction. Therefore, TDM of aminoglycosides is important due to their ototoxicity and nephrotoxicity. Here, we have developed a hot embossed poly (methyl methacrylate) (PMMA) microfluidic device featuring an electrokinetic size and mobility trap (SMT) to purify, concentrate, and separate the aminoglycoside antibiotic drugs amikacin, gentamicin, and tobramycin. These drugs were separated successfully from whole blood within 3 min, with 30-fold lower detection limits compared to a standard pinched injection. The limit of detections (LOD) were 3.75 &#181;g/mL for gentamicin, 8.53 &#181;g/mL for amikacin, and 6.00 &#181;g/mL for tobramycin. These are sufficient to cover the therapeutic range for treating sepsis of 6&#8315;10 &#956;g/mL gentamicin and tobramycin and 12&#8315;20 &#956;g/mL of amikacin. The device is simple and could be mass produced via embossing or injection molding approaches

Microfluidic device for studying traumatic brain injury

Throughout the world, traumatic brain injury (TBI), for example, as a result of motor vehicle accident, is a major cause of mortality and lifelong disability in children and young adults. Studies show that axonal pathology and degeneration can cause significant functional impairment and can precede, and sometimes cause, neuronal death in several neurological disorders including TBI, creating a compelling need to understand the mechanisms of axon degeneration. Microfluidic devices that allow manipulation of fluids in channels with typical dimensions of tens to hundreds of micrometers have emerged as a powerful platform for such studies due to their ability to isolate and direct the growth of axons. Here, we describe a new microfluidic platform that can be used to study TBI by applying very mild (0.5%) and mild (5%) stretch injury to individual cortical axons through the incorporation of microfluidic valve technology into a compartmented microfluidic-culturing device. This device is unique due to its ability to study the neuronal response to axonal stretch injury in a fluidically isolated microenvironment

Mild and repetitive very mild axonal stretch injury triggers cystoskeletal mislocalization and growth cone collapse

<div><p>Diffuse axonal injury is a hallmark pathological consequence of non-penetrative traumatic brain injury (TBI) and yet the axonal responses to stretch injury are not fully understood at the cellular level. Here, we investigated the effects of mild (5%), very mild (0.5%) and repetitive very mild (2×0.5%) axonal stretch injury on primary cortical neurons using a recently developed compartmentalized <i>in vitro</i> model. We found that very mild and mild levels of stretch injury resulted in the formation of smaller growth cones at the tips of axons and a significantly higher number of collapsed structures compared to those present in uninjured cultures, when measured at both 24 h and 72 h post injury. Immunocytochemistry studies revealed that at 72 h following mild injury the axonal growth cones had a significantly higher colocalization of <i>β</i>III tubulin and F-actin and higher percentage of collapsed morphology than those present following a very mild injury. Interestingly, cultures that received a second very mild stretch injury, 24 h after the first insult, had a further increased proportion of growth cone collapse and increased <i>β</i>III tubulin and F-actin colocalization, compared with a single very mild injury at 72 h PI. In addition, our results demonstrated that microtubule stabilization of axons using brain penetrant Epothilone D (EpoD) (100 nM) resulted in a significant reduction in the number of fragmented axons following mild injury. Collectively, these results suggest that mild and very mild stretch injury to a very localized region of the cortical axon is able to trigger a degenerative response characterized by growth cone collapse and significant abnormal cytoskeletal rearrangement. Furthermore, repetitive very mild stretch injury significantly exacerbated this response. Results suggest that axonal degeneration following stretch injury involves destabilization of the microtubule cytoskeleton and hence treatment with EpoD reduced fragmentation. Together, these results contribute a better understanding of the pathogenesis of mild and repetitive TBI and highlight the therapeutic effect of microtubule targeted drugs on distal part of neurons using a compartmentalized culturing model.</p></div

Graphs showing the mean percentages of collapse growth cone and the extent of colocalizatuon of F actin and <i>β</i>III tubulin in growth cones of control cultures and cultures after 0.5% stretched, 5% stretched and repetitive very mild (2×0.5%) stretched axons at different time point.

<p><b>(A)</b> Stretch injury induced increased axonal growth cone collapsed at both 24 h and 72 h PI compared to the control. In addition, repetitive very mild (2×0.5%) stretch injury induced more collapsed growth cones when compared to single 0.5% stretched axon at 72 h PI. <b>(B)</b> The growth cones in 5% stretched axon had significantly higher colocalization value of <i>β</i>III tubulin and F-actin compared to both the growth cones in control and 0.5% stretched axon at 72 h PI. However, there was no significant difference between the growth cones in control, 0.5% stretched or 5% stretched axon at 24 h PI. The growth cones in 2×0.5% repetitive stretched axon has significantly higher colocalization value of <i>β</i>III tubulin and F-actin if compare to both the growth cones in control and single 0.5% stretched axon at 72 h PI. *p<0.05. Error bar = mean ± SEM.</p

Tau (microtubule marker) immunofluorescence labeling demonstrating the effect of EpoD exposure on 5% stretched axons at 7 DIV.

<p><b>(A)</b> Representative fluorescence images of unstretched and stretched culture 24 h after the indicated treatment. <b>(B)</b> EpoD (100 nM) applied to axon compartment alone for 24 h induced a significant decrease in degenerative index in the axon compartment when compared to vehicle- treated cultures following injury. The arterisk indicates the difference from paired control. *<i>p</i><0.05. Error bar = mean ± SEM. Scale bar = 30 <i>μ</i>m.</p