Characterising molecular mechanisms of Crohn’s disease-associated Escherichia coli that enable their survival and replication within macrophages.

Mucosa-associated adherent, invasive Escherichia coli (AIEC), found in increased number in Crohn’s disease (CD) ileal and colonic mucosae, can survive and replicate within underlying host immune competent cells (e.g. macrophages and dendritic cells) without triggering host cell death. The intra-macrophage environment plays an essential role in bacterial killing where engulfed bacteria are exposed to a hostile environment of low pH, high levels of proteolytic/lysosomal enzymes, high nitrosative and high oxidative stress, and the activation of a respiratory burst with generation of superoxide ions. Although a few stress response genes have been identified that likely support the paradigm ileal AIEC isolate LF82 to survive and replicate within the macrophage, the key molecular mechanisms involved in supporting Crohn’s disease (CD) mucosa-associated AIEC to resist killing by host mucosal macrophages within harsh environment of the phagolysosome still remains largely unclear. Here we aimed to compare the ability of a number of E. coli strains to survive and replicate inside macrophages, including a number of clinical isolates (from CD, colorectal cancer (CRC) and ulcerative colitis (UC) patients and other infective or non-inflamed sources), and this to toleration of growth in chemical-induced stress conditions mimicking the intra-phagolysosome environment. In addition, a focus was to further understand the molecular mechanisms responsible for acid tolerance of the paradigm CD isolates and examine their replication within macrophages defective in NF-κB pathway signalling. Finally, to also assess whether CD AIEC possess ability to alter host oxidative stress response gene expression in macrophages to support their survival/replication. Both ileal and colonic CD isolates (AIEC) were found to possess ability to either survive and/or replicate within murine macrophages (i.e. J774-A1 cell-line and wild-type (WT) C57BL/6 bone marrow derived macrophages [BMDM]) and to tolerate all stress conditions mimicking those within the phagolysosome, e.g. low nutrient, high acid, high nitrosative, high oxidative stress including exposure to superoxide ions. Interestingly pathogenic E. coli isolates from urinary tract infection (UTI) and some healthy-mucosa associated E. coli strains behaved similarly. Crohn’s AIEC were unable to survive and replicate inside Nfκb1-/- and Nfκb2-/- BMDM, whilst they survived/replicated within WT and c-Rel-/- BMDM. Thus Crohn’s AIEC survival and replication appears dependent on host NFκB signalling within the macrophage. Conversely, all CRC and UC isolates tested and the majority of laboratory E. coli strains studied were unable to survive inside murine J774-A1 macrophage phagolysosomes and they were also intolerant to most stress conditions, in particular superoxidative stress. Colonic CD AIEC isolate HM605 showed higher initial levels of expression of acid response genes gadA and gadB that may support adaptation to the intra-macrophage phagolysosome niche. Adaptation to an intra-macrophage lifestyle appeared not to be through any ability to alter host macrophage oxidative stress response to infection as no differential changes were observed in the expression of 84 host genes related to oxidative stress to that seen with non-replicating laboratory E. coli strain. Overall this study provides new insight into how CD mucosa-associated E. coli isolates resist killing by mucosal macrophages through adaptation to the acidic, high oxidative environment within the macrophage phagolysosome. The data may support future development of new therapeutic strategies that target the fundamental pathology of CD, in particular support a reduction in bacterial persistence/increased killing of intra-macrophage E. coli in CD patient mucosae

Measuring multiple residual-stress components using the contour method and multiple cuts

The conventional contour method determines one component of stress over the cross section of a part. The part is cut into two, the contour of the exposed surface is measured, and Bueckner's superposition principle is analytically applied to calculate stresses. In this paper, the contour method is extended to the measurement of multiple stress components by making multiple cuts with subsequent applications of superposition. The theory and limitations are described. The theory is experimentally tested on a 316L stainless steel disk with residual stresses induced by plastically indenting the central portion of the disk. The stress results are validated against independent measurements using neutron diffraction. The theory has implications beyond just multiple cuts. The contour method measurements and calculations for the first cut reveal how the residual stresses have changed throughout the part. Subsequent measurements of partially relaxed stresses by other techniques, such as laboratory x-rays, hole drilling, or neutron or synchrotron diffraction, can be superimposed back to the original state of the body

Laparoscopy in management of appendicitis in high-, middle-, and low-income countries: a multicenter, prospective, cohort study.

BACKGROUND: Appendicitis is the most common abdominal surgical emergency worldwide. Differences between high- and low-income settings in the availability of laparoscopic appendectomy, alternative management choices, and outcomes are poorly described. The aim was to identify variation in surgical management and outcomes of appendicitis within low-, middle-, and high-Human Development Index (HDI) countries worldwide. METHODS: This is a multicenter, international prospective cohort study. Consecutive sampling of patients undergoing emergency appendectomy over 6 months was conducted. Follow-up lasted 30 days. RESULTS: 4546 patients from 52 countries underwent appendectomy (2499 high-, 1540 middle-, and 507 low-HDI groups). Surgical site infection (SSI) rates were higher in low-HDI (OR 2.57, 95% CI 1.33-4.99, p = 0.005) but not middle-HDI countries (OR 1.38, 95% CI 0.76-2.52, p = 0.291), compared with high-HDI countries after adjustment. A laparoscopic approach was common in high-HDI countries (1693/2499, 67.7%), but infrequent in low-HDI (41/507, 8.1%) and middle-HDI (132/1540, 8.6%) groups. After accounting for case-mix, laparoscopy was still associated with fewer overall complications (OR 0.55, 95% CI 0.42-0.71, p < 0.001) and SSIs (OR 0.22, 95% CI 0.14-0.33, p < 0.001). In propensity-score matched groups within low-/middle-HDI countries, laparoscopy was still associated with fewer overall complications (OR 0.23 95% CI 0.11-0.44) and SSI (OR 0.21 95% CI 0.09-0.45). CONCLUSION: A laparoscopic approach is associated with better outcomes and availability appears to differ by country HDI. Despite the profound clinical, operational, and financial barriers to its widespread introduction, laparoscopy could significantly improve outcomes for patients in low-resource environments. TRIAL REGISTRATION: NCT02179112

Pooled analysis of WHO Surgical Safety Checklist use and mortality after emergency laparotomy

Background The World Health Organization (WHO) Surgical Safety Checklist has fostered safe practice for 10 years, yet its place in emergency surgery has not been assessed on a global scale. The aim of this study was to evaluate reported checklist use in emergency settings and examine the relationship with perioperative mortality in patients who had emergency laparotomy. Methods In two multinational cohort studies, adults undergoing emergency laparotomy were compared with those having elective gastrointestinal surgery. Relationships between reported checklist use and mortality were determined using multivariable logistic regression and bootstrapped simulation. Results Of 12 296 patients included from 76 countries, 4843 underwent emergency laparotomy. After adjusting for patient and disease factors, checklist use before emergency laparotomy was more common in countries with a high Human Development Index (HDI) (2455 of 2741, 89.6 per cent) compared with that in countries with a middle (753 of 1242, 60.6 per cent; odds ratio (OR) 0.17, 95 per cent c.i. 0.14 to 0.21, P <0001) or low (363 of 860, 422 per cent; OR 008, 007 to 010, P <0.001) HDI. Checklist use was less common in elective surgery than for emergency laparotomy in high-HDI countries (risk difference -94 (95 per cent c.i. -11.9 to -6.9) per cent; P <0001), but the relationship was reversed in low-HDI countries (+121 (+7.0 to +173) per cent; P <0001). In multivariable models, checklist use was associated with a lower 30-day perioperative mortality (OR 0.60, 0.50 to 073; P <0.001). The greatest absolute benefit was seen for emergency surgery in low- and middle-HDI countries. Conclusion Checklist use in emergency laparotomy was associated with a significantly lower perioperative mortality rate. Checklist use in low-HDI countries was half that in high-HDI countries.Peer reviewe

Global variation in anastomosis and end colostomy formation following left-sided colorectal resection

Background End colostomy rates following colorectal resection vary across institutions in high-income settings, being influenced by patient, disease, surgeon and system factors. This study aimed to assess global variation in end colostomy rates after left-sided colorectal resection. Methods This study comprised an analysis of GlobalSurg-1 and -2 international, prospective, observational cohort studies (2014, 2016), including consecutive adult patients undergoing elective or emergency left-sided colorectal resection within discrete 2-week windows. Countries were grouped into high-, middle- and low-income tertiles according to the United Nations Human Development Index (HDI). Factors associated with colostomy formation versus primary anastomosis were explored using a multilevel, multivariable logistic regression model. Results In total, 1635 patients from 242 hospitals in 57 countries undergoing left-sided colorectal resection were included: 113 (6·9 per cent) from low-HDI, 254 (15·5 per cent) from middle-HDI and 1268 (77·6 per cent) from high-HDI countries. There was a higher proportion of patients with perforated disease (57·5, 40·9 and 35·4 per cent; P < 0·001) and subsequent use of end colostomy (52·2, 24·8 and 18·9 per cent; P < 0·001) in low- compared with middle- and high-HDI settings. The association with colostomy use in low-HDI settings persisted (odds ratio (OR) 3·20, 95 per cent c.i. 1·35 to 7·57; P = 0·008) after risk adjustment for malignant disease (OR 2·34, 1·65 to 3·32; P < 0·001), emergency surgery (OR 4·08, 2·73 to 6·10; P < 0·001), time to operation at least 48 h (OR 1·99, 1·28 to 3·09; P = 0·002) and disease perforation (OR 4·00, 2·81 to 5·69; P < 0·001). Conclusion Global differences existed in the proportion of patients receiving end stomas after left-sided colorectal resection based on income, which went beyond case mix alone

Evisceration

Evisceration is defined as the removal of the intraocular contents while leaving the sclera intact. It has theoretical advantages over enucleation, including better motility and less volume loss owing to leaving the extraocular muscle scleral attachments intact and not disrupting the deep orbital tissues. However, there are also potential disadvantages including a small risk of sympathetic ophthalmia due to exposure of uveal tissue to the circulation and the possible inadvertent spread of an undiagnosed intraocular neoplasm such as a small uveal melanoma. Controversies regarding this surgery include the timing and type of orbital implant placement. This chapter covers these topics as well as describes the surgical technique of evisceration