A Novel Algorithm for Improving the Prehospital Diagnostic Accuracy of ST-Segment Elevation Myocardial Infarction

INTRODUCTION

Early detection of ST-segment elevation myocardial infarction (STEMI) on the prehospital electrocardiogram (ECG) improves patient outcomes. Current software algorithms optimize sensitivity but have a high false-positive rate. The authors propose an algorithm to improve the specificity of STEMI diagnosis in the prehospital setting.

METHODS

A dataset of prehospital ECGs with verified outcomes was used to validate an algorithm to identify true and false-positive software interpretations of STEMI. Four criteria implicated in prior research to differentiate STEMI true positives were applied: heart rate <130, QRS <100, verification of ST-segment elevation, and absence of artifact. The test characteristics were calculated and regression analysis was used to examine the association between the number of criteria included and test characteristics.

RESULTS

There were 44,611 cases available. Of these, 1,193 were identified as STEMI by the software interpretation. Applying all four criteria had the highest positive likelihood ratio of 353 (95% CI, 201-595) and specificity of 99.96% (95% CI, 99.93-99.98), but the lowest sensitivity (14%; 95% CI, 11-17) and worst negative likelihood ratio (0.86; 95% CI, 0.84-0.89). There was a strong correlation between increased positive likelihood ratio (r2 = 0.90) and specificity (r2 = 0.85) with increasing number of criteria.

CONCLUSIONS

Prehospital ECGs with a high probability of true STEMI can be accurately identified using these four criteria: heart rate <130, QRS <100, verification of ST-segment elevation, and absence of artifact. Applying these criteria to prehospital ECGs with software interpretations of STEMI could decrease false-positive field activations, while also reducing the need to rely on transmission for physician over-read. This can have significant clinical and quality implications for Emergency Medical Services (EMS) systems.

Defining core patient descriptors for perforated peptic ulcer research: international Delphi

BACKGROUND

Perforated peptic ulcer (PPU) remains a common condition globally with significant morbidity and mortality. Previous work has demonstrated variation in reporting of patient characteristics in PPU studies, making comparison of studies and outcomes difficult. The aim of this study was to standardize the reporting of patient characteristics, by creating a core descriptor set (CDS) of important descriptors that should be consistently reported in PPU research.

METHODS

Candidate descriptors were identified through systematic review and stakeholder proposals. An international Delphi exercise involving three survey rounds was undertaken to obtain consensus on key patient characteristics for future research. Participants rated items on a scale of 1-9 with respect to their importance. Items meeting a predetermined threshold (rated 7-9 by over 70 per cent of stakeholders) were included in the final set and ratified at a consensus meeting. Feedback was provided between rounds to allow refinement of ratings.

RESULTS

Some 116 clinicians were recruited from 29 countries. A total of 63 descriptors were longlisted from the literature, and 27 were proposed by stakeholders. After three survey rounds and a consensus meeting, 27 descriptors were included in the CDS. These covered demographic variables and co-morbidities, risk factors for PPU, presentation and pathway factors, need for organ support, biochemical parameters, prognostic tools, perforation details, and surgical history.

CONCLUSION

This study defines the core descriptive items for PPU research, which will allow more robust synthesis of studies.

Normal form for the onset of collapse: The prototypical example of the nonlinear Schrödinger equation

The study of nonlinear waves that collapse in finite time is a theme of universal interest, e.g., within optical, atomic, plasma physics, and nonlinear dynamics. Here we revisit the quintessential example of the nonlinear Schrödinger equation and systematically derive a normal form for the emergence of radially symmetric blowup solutions from stationary ones. While this is an extensively studied problem, such a normal form, based on the methodology of asymptotics beyond all algebraic orders, applies to both the dimension-dependent and power-law-dependent bifurcations previously studied. It yields excellent agreement with numerics in both leading and higher-order effects, it is applicable to both infinite and finite domains, and it is valid in both critical and supercritical regimes.

O32: TRANSPARENCY IN SURGICAL RANDOMISED CONTROLLED TRIALS: CROSS-SECTIONAL, OBSERVATIONAL STUDY

Introduction

Randomised controlled trials (RCT) often provide the scientific basis on which commissioning and treatment decisions are made. It is essential that their results and methods are reported transparently. The aim of this study was to explore transparency with respect to trial registration, disclosure of funding sources, conflicts of interest (COI), and data sharing.

Method

This was a cross-sectional review of surgical RCTs. Data were extracted from RCTs in ten high-impact journals published in the years 2009, 2012, 2015, and 2018. Outcomes of interest were the incidence of reported trial registration, disclosure of funding sources, disclosure of investigator COI, and presence of a statement of data sharing plans.

Result

A total of 475 were eligible for analysis. Trial registration was present in 73 (67%) studies in 2009, 137 (84%) in 2012, 111 (89%) in 2015 and 110 (93%) in 2018. Funding statements were provided in 55%, 65%, 69.4%, and 75.4% of manuscripts, respectively. Conflicts of interest statements were provided in 49.5%, 89.1%, 94.6%, and 98.3% of manuscripts, respectively. Data sharing statements were present in only 15 (3.2%) RCTs. Eleven of these were in studies published most recently in 2018.

Conclusion

Trial registration, presence of funding statements, and disclosure of personal conflicts of interest in surgical RCTs have improved rapidly over the last 10 years. In contrast, disclosure of data sharing plans is exceptionally low. This may contribute to research waste and represents an essential target for improvement.

Take-home message

Trial registration, presence of funding statements, and disclosure of personal conflicts of interest in surgical RCTs have improved rapidly over the last 10 years. In contrast, disclosure of data sharing plans is exceptionally low. This may contribute to research waste and represents an essential target for improvement.

P14: DISCONTINUATION AND NON-PUBLICATION OF SURGICAL RANDOMISED CONTROLLED TRIALS IN THE SETTING OF ILEUS: OBSERVATIONAL STUDY

Introduction

Once regarded as an inevitable occurrence after surgery, ileus is now recognised as an unmet clinical need. Despite this, few studies have shown meaningful clinical benefit which may be due to the challenges associated with conducting trials in this setting. The aim of this study was to determine the rate of discontinuation and non-publication of randomised controlled trials (RCTs) in the setting of ileus.

Method

A systematic search of ClinicalTrials.gov was performed using the keyword “ileus”. RCTs registered between 2003-2019 involving abdominal surgery were eligible. Studies were divided according to completion status. Authors were contacted to seek information about the circumstances for discontinuation and non-publication. For completed studies, evidence of a published manuscript was sought.

Result

Of 262 trials identified, 81 were eligible for analysis. Amongst 27 discontinued trials, email addresses were identified for 24 (88.9%) and replies received from 6 (25.1%). The most common reasons for discontinuation were loss of clinical significance (n=2) and insufficient recruitment (n=2). Amongst 54 completed studies, manuscripts were identified for 34 (63.0%). Of these, email addresses were identified for 12 (60.0%) and replies received from 5 (41.7%). The most common reason for non-publication was a lack of time/resources/personnel (n=3).

Conclusion

One third of trials undertaken were discontinued and of those which did reach completion, less than two thirds reported results. A lack of resources and loss of clinical significance were predominant reasons. There is an urgent need to address methodological barriers in research relating to ileus to promote rigorous evaluation of new treatments.

Take-home message

One third of trials undertaken were discontinued and of those which did reach completion, less than two thirds reported results. A lack of resources and loss of clinical significance were predominant reasons. There is an urgent need to address methodological barriers in research relating to ileus to promote rigorous evaluation of new treatments.

Patient education about recovery after colorectal surgery: systematic scoping review

AIM

Enhanced recovery after surgery (ERAS) protocols aim to optimize recovery through a series of evidence-based recommendations. A key component of ERAS is the provision of patient education. Whilst the recommendation for this is strong, the evidence to inform its format, timing and delivery is unclear. The aim of this review was to describe previous educational interventions used to improve recovery after colorectal surgery and to explore opportunities for future research.

METHODS

A systematic scoping review was performed. MEDLINE and Embase databases were searched between 1 January 1990 and 12 February 2020. Studies which described or assessed the effectiveness of a patient education or information resource to improve recovery after colorectal surgery were eligible. Outcomes of interest included the format, timing and delivery of interventions, as well as key features of intervention and study design. A narrative synthesis of data was produced through a process of charting and summarizing key results.

RESULTS

A total of 1298 papers were inspected, and 11 were eligible for inclusion. Five papers were reports of randomized controlled trials, and others reported a mix of non-randomized and qualitative studies. The design of educational interventions included audio-visual resources (n = 3), smartphone device applications (n = 3) and approaches to facilitate person-to-person counselling (n = 5). Most of the counselling interventions reported positive outcomes (mainly in length of hospital stay), whereas the other types reported mixed results. Patients and the public were seldom involved as collaborators in the design of interventions.

CONCLUSIONS

Patient education is generally advantageous, but there is insufficient evidence to optimize its design and delivery in the setting of colorectal surgery.

Transparency in surgical randomized clinical trials: cross-sectional observational study

BACKGROUND

RCTs provide the scientific basis upon which treatment decisions are made. To facilitate critical review, it is important that methods and results are reported transparently. The aim of this study was to explore transparency in surgical RCTs with respect to trial registration, disclosure of funding sources, declarations of investigator conflicts and data-sharing.

METHODS

This was a cross-sectional review of published surgical RCTs. Ten high-impact journals were searched systematically for RCTs published in years 2009, 2012, 2015 and 2018. Four domains of transparency were explored: trial registration, disclosure of funding, disclosure of investigator conflicts, and a statement relating to data-sharing.

RESULTS

Of 611 RCTs, 475 were eligible for analysis. Some 397 RCTs (83.6 per cent) were registered on a trial database, of which 190 (47·9 per cent) had been registered prospectively. Prospective registration increased over time (26 per cent in 2009, 33·0 per cent in 2012, 54 per cent in 2015, and 72·7 per cent in 2018). Funding disclosure was present in 55·0, 65·0, 69·4 and 75·4 per cent of manuscripts respectively. Conflict of interest disclosure was present in 49·5, 89·1, 94·6 and 98·3 per cent of manuscripts across the same time periods. Data-sharing statements were present in only 15 RCTs (3·2 per cent), 11 of which were published in 2018.

CONCLUSION

Trial registration, disclosure of funding and disclosure of investigator conflicts in surgical RCTs have improved markedly over the past 10 years. Disclosure of data-sharing plans is exceptionally low. This may contribute to research waste and represents a target for improvement.

The outcome of pregnancy in women with cystic fibrosis: a UK population-based descriptive study

OBJECTIVE

To estimate the incidence of cystic fibrosis in pregnancy and to explore obstetric and neonatal outcomes.

DESIGN

A population-based descriptive study using the methodology of the UK Obstetric Surveillance System (UKOSS).

SETTING

All consultant-led maternity units in the UK.

POPULATION

All pregnant women with a diagnosis of cystic fibrosis who booked for antenatal care in a UK obstetric unit between March 2015 and February 2017.

METHODS

Prospective case collection identified using UKOSS monthly notification.

MAIN OUTCOME MEASURES

Incidence, maternal morbidity, maternal mortality, gestation at delivery, neonatal mortality, neonatal morbidity.

RESULTS

We report 71 pregnancies over a 2-year period. There was one early miscarriage, four terminations and three sets of twins, resulting in the live birth of 69 infants. There were no maternal deaths. One infant died following spontaneous preterm birth at 29 weeks' gestation. The mean gestation at delivery was 36.2 completed weeks. The mean birthweight centile for gestational age was the 61st centile. We report a positive correlation between both maternal lung function (FEV₁ ) and mean gestation at delivery, and between FEV₁ and mean birthweight centile for gestational age.

CONCLUSIONS

Pregnancy outcomes are generally good in women with cystic fibrosis. Successful pregnancy is possible even in those women with FEV₁ <60% predicted, although such women have higher chance of preterm delivery and a smaller baby.

TWEETABLE ABSTRACT

Pregnant women with cystic fibrosis who have poorer lung function at the beginning of pregnancy have a higher risk of having a premature or smaller baby.

Establishing core outcome sets for gastrointestinal recovery in studies of postoperative ileus and small bowel obstruction: protocol for a nested methodological study

INTRODUCTION

Gastrointestinal recovery describes the restoration of normal bowel function in patients with bowel disease. This may be prolonged in two common clinical settings: postoperative ileus and small bowel obstruction. Improving gastrointestinal recovery is a research priority but researchers are limited by variation in outcome reporting across clinical studies. This protocol describes the development of core outcome sets for gastrointestinal recovery in the contexts of postoperative ileus and small bowel obstruction.

METHOD

An international Steering Group consisting of patient and clinician representatives has been established. As overlap between clinical contexts is anticipated, both outcome sets will be co-developed and may be combined to form a common output with disease-specific domains. The development process will comprise three phases, including definition of outcomes relevant to postoperative ileus and small bowel obstruction from systematic literature reviews and nominal-group stakeholder discussions; online-facilitated Delphi surveys via international networks; and a consensus meeting to ratify the final output. A nested study will explore if the development of overlapping outcome sets can be rationalized.

DISSEMINATION AND IMPLEMENTATION

The final output will be registered with the Core Outcome Measures in Effectiveness Trials initiative. A multi-faceted, quality improvement campaign for the reporting of gastrointestinal recovery in clinical studies will be launched, targeting international professional and patient groups, charitable organizations and editorial committees. Success will be explored via an updated systematic review of outcomes 5 years after registration of the core outcome set.

Randomized controlled trial of plain English and visual abstracts for disseminating surgical research via social media

BACKGROUND

Patients are increasingly taking an active role in the design and delivery of surgical research. Public communication of results should also be encouraged, but this is often limited to non-expert commentary. This study assessed the role of plain English abstracts disseminated via social media in engaging patients and clinicians in the communication of surgical research.

METHODS

A three-arm randomized controlled trial with crossover of two intervention arms was performed. Manuscripts accepted for publication in BJS were allocated to one of three arms and disseminated via Twitter: plain English abstracts, visual abstracts and standard tweets. The primary outcome was online engagement (a composite of tweets, replies and likes) by members of the public within 14 days. The secondary outcome was online engagement by healthcare professionals.

RESULTS

Forty-one manuscripts were randomized to plain English abstracts (14), visual abstracts (14) and standard tweets (13). The number of public engagements was low, with a mean of 1·8 (range 0-8), 2·5 (0-11), and 1·2 (0-4) for plain English abstracts, visual abstracts and standard tweets respectively. The mean number of engagements by healthcare professionals was 29·4 (6-66), 45·3 (6-161) and 28·8 (10-52) respectively. Overall, visual abstracts attracted a significantly greater number of engagements than plain English ones (P < 0·001).

CONCLUSION

Online, public engagement with surgical research was low. Overall engagement (predominantly from healthcare professionals) was enhanced by the use of visual abstracts.

Research waste in surgical randomized controlled trials

BACKGROUND

Research waste is a major challenge for evidence-based medicine. It implicates misused resources and increased risks for research participants. The aim of this study was to quantify constituent components of waste in surgical RCTs and explore targets for improvement.

METHODS

ClinicalTrials.gov was searched for RCTs registered between January 2011 and December 2012 using the keyword 'surgery'. The primary outcome was research waste, defined as non-publication, inadequate reporting or presence of an avoidable design limitation. Serial systematic searches of PubMed and Scopus databases were performed to determine publication status. Adequacy of reporting was assessed using the CONSORT checklist. Avoidable design limitations were evaluated according to the presence of bias and/or the absence of a cited systematic review of the literature.

RESULTS

Of 5617 registered RCTs, 304 met all eligibility criteria. Overall, 259 of 304 (85·2 per cent) demonstrated at least one feature of waste. Of these, 221 (72·7 per cent) were published in a peer-reviewed journal and 219 were accessible for full-text review. Only 73 of 131 (55·7 per cent) RCTs with a pharmacological intervention and 24 of 88 (27 per cent) with a non-pharmacological intervention were reported adequately, and 159 of 219 (72·6 per cent) demonstrated an avoidable design limitation. Multicentre (odds ratio 0·31, 95 per cent c.i. 0·11 to 0·88) and externally funded (OR 0·35, 0·15 to 0·82) RCTs were less associated with research waste.

CONCLUSION

This study identified a considerable burden of research waste in surgical RCTs. Future initiatives should target improvements in single-centre, poorly supported RCTs.

Systematic review of definitions and outcome measures for return of bowel function after gastrointestinal surgery

Background

Ileus is common after gastrointestinal surgery and has been identified as a research priority. Several issues have limited previous research, including a widely accepted definition and agreed outcome measure. This review is the first stage in the development of a core outcome set for the return of bowel function after gastrointestinal surgery. It aims to characterize the extent of variation in current outcome reporting.

Methods

A systematic search of MEDLINE, Embase, CINAHL (Cumulative Index to Nursing and Allied Health Literature) and the Cochrane Library was performed for 1990–2017. RCTs of adults undergoing gastrointestinal surgery, including at least one reported measure relating to return of bowel function, were eligible. Trial registries were searched across the same period for ongoing and completed (but not published) RCTs. Definitions of ileus and outcome measures describing the return of bowel function were extracted.

Results

Of 5670 manuscripts screened, 215 (reporting 217 RCTs) were eligible. Most RCTs involved patients undergoing colorectal surgery (161 of 217, 74·2 per cent). A total of 784 outcomes were identified across all published RCTs, comprising 73 measures (clinical: 63, 86 per cent; radiological: 6, 8 per cent; physiological: 4, 5 per cent). The most commonly reported outcome measure was ‘time to first passage of flatus’ (140 of 217, 64·5 per cent). The outcomes ‘ileus’ and ‘prolonged ileus’ were defined infrequently and variably.

Conclusion

Outcome reporting for the return of bowel function after gastrointestinal surgery is variable and not fit for purpose. An agreed core outcome set will improve the consistency, reliability and clinical value of future studies.

Systematic review of the stage of innovation of biological mesh for complex or contaminated abdominal wall closure

Background

Achieving stable closure of complex or contaminated abdominal wall incisions remains challenging. This study aimed to characterize the stage of innovation for biological mesh devices used during complex abdominal wall reconstruction and to evaluate the quality of current evidence.

Methods

A systematic review was performed of published and ongoing studies between January 2000 and September 2017. Eligible studies were those where a biological mesh was used to support fascial closure, either prophylactically after midline laparotomy, or for reinforcement after repair of incisional hernia with midline incision. The primary outcome measure was the IDEAL framework stage of innovation. The key secondary outcome measure was the GRADE criteria for study quality.

Results

Thirty‐five studies including 2681 patients were included. Four studies considered mesh prophylaxis, 23 considered hernia repair, and eight reported on both. There was one published randomized trial (IDEAL stage 3), none of which was of high quality; the others were non‐randomized studies (IDEAL stage 2a). A detailed description of surgical technique was provided in most studies (27 of 35); however, no study reported outcomes according to the European Hernia Society consensus statement and only two described quality control of surgical technique during the study. From 21 ongoing randomized trials and observational studies, 11 considered repair of incisional hernia and 10 considered prophylaxis (seven in elective settings).

Conclusion

The evidence base for biological mesh is limited, and better reporting and quality control of surgical techniques are needed. Although results of ongoing trials over the next decade will improve the evidence base, further study is required in the emergency and contaminated settings.

Postoperative ileus following major colorectal surgery

BACKGROUND

Postoperative ileus (POI) is characterized by delayed gastrointestinal recovery following surgery. Current knowledge of pathophysiology, clinical interventions and methodological challenges was reviewed to inform modern practice and future research.

METHODS

A systematic search of MEDLINE and Embase databases was performed using search terms related to ileus and colorectal surgery. All RCTs involving an intervention to prevent or reduce POI published between 1990 and 2016 were identified. Grey literature, non-full-text manuscripts, and reanalyses of previous RCTs were excluded. Eligible articles were assessed using the Cochrane tool for assessing risk of bias.

RESULTS

Of 5614 studies screened, 86 eligible articles describing 88 RCTs were identified. Current knowledge of pathophysiology acknowledges neurogenic, inflammatory and pharmacological mechanisms, but much of the evidence arises from animal studies. The most common interventions tested were chewing gum (11 trials) and early enteral feeding (11), which are safe but of unclear benefit for actively reducing POI. Others, including thoracic epidural analgesia (8), systemic lidocaine (8) and peripheral μ antagonists (5), show benefit but require further investigation for safety and cost-effectiveness.

CONCLUSION

POI is a common condition with no established definition, aetiology or treatment. According to current literature, minimally invasive surgery, protocol-driven recovery (including early feeding and opioid avoidance strategies) and measures to avoid major inflammatory events (such as anastomotic leak) offer the best chances of reducing POI.

Ileus Management International (IMAGINE): protocol for a multicentre, observational study of ileus after colorectal surgery

AIM

The management of postoperative ileus following colorectal surgery remains controversial. It is the commonest complication after elective colorectal resection and is associated with an increased incidence of postoperative adverse events. The prevention and management of postoperative ileus remains unstandardized. This study aims to describe an international profile of gastrointestinal recovery after colorectal surgery and will assess the role of non-steroidal anti-inflammatory drugs, when used as postoperative analgesia, in expediting the return of gastrointestinal function.

METHODS

A multicentre, student- and trainee-led, prospective cohort study will be conducted across both Europe and Australasia. Adult patients undergoing elective colorectal resection during 2-week data collection periods between January and April 2018 will be included. A site-specific questionnaire will capture compliance to Enhanced Recovery after Surgery components at participating centres. The primary outcome is time to gastrointestinal recovery, measured using a composite outcome of bowel function and oral tolerance. The impact of non-steroidal anti-inflammatory drugs on gastrointestinal recovery will be evaluated along with safety data with respect to anastomotic leak, acute kidney injury and complications within 30 days of surgery.

DISCUSSION

This protocol describes the methodology of an international, observational assessment of gastrointestinal recovery after colorectal surgery. It discusses key challenges and describes how the results will impact on future investigation. The study will be conducted across a large student- and trainee-led collaborative network, with prospective quality assurance and data validation strategies.

#colorectalsurgery

BACKGROUND

The use of social media platforms among healthcare professionals is increasing. A Twitter social media campaign promoting the hashtag #colorectalsurgery was launched with the aim of providing a specialty-specific forum to collate discussions and science relevant to an engaged, global community of coloproctologists. This article reviews initial experiences of the early adoption, engagement and utilization of this pilot initiative.

METHODS

The hashtag #colorectalsurgery was promoted via the online microblogging service Twitter across a 180-day interval. Data on all tweets containing the #colorectalsurgery hashtag were analysed using online analytical tools. Data included total number of tweets, number of views, and user engagement since registration and launch of the campaign. Content of tweet and user demographic analysis was undertaken.

RESULTS

The number of tweets using #colorectalsurgery grew rapidly following the launch on 24 April 2016; #colorectalsurgery was used in 15 708 tweets, which resulted in 65 398 696 impressions and involved 1863 individual Twitter accounts. Increased volumes of #colorectalsurgery tweets were noted in association with the timing of three major international colorectal surgical conferences, and geographical trends were noted. Some 88·4 per cent of all posts were by male users. The top 25 users by volume of #colorectalsurgery tweets had considerable influence and posted 8023 tweets (51·1 per cent).

CONCLUSION

Online global communities formed via healthcare-related hashtags, such as #colorectalsurgery, unify social media posts, scientists, surgeons and authors who have an interest in coloproctology. Furthermore, they facilitate greater connectivity among geographically separate users.

Cross-sectional observational study of the availability of evidence supporting novel implantable devices used in gastrointestinal surgery

BACKGROUND

Evidence supporting the implementation of novel surgical devices is unstandardized, despite recommendations for assessing novel innovations. This study aimed to determine the proportion of novel implantable devices used in gastrointestinal surgery that are supported by evidence from RCTs.

METHODS

A list of novel implantable devices placed intra-abdominally during gastrointestinal surgery was produced. Systematic searches were performed for all devices via PubMed and clinical trial registries. The primary outcome measure was the availability of at least one published RCT for each device. Published RCTs were appraised using the Cochrane tool for assessing risk of bias.

RESULTS

A total of 116 eligible devices were identified (implantable mesh 42, topical haemostatics 22, antiadhesion barriers 10, gastric bands 8, suture and staple-line reinforcement 7, artificial sphincters 5, other 22). One hundred and twenty-eight published RCTs were found for 33 of 116 devices (28·4 per cent). Most were assessed as having a high risk of bias, with only 12 of 116 devices (10·3 per cent) supported by a published RCT considered to be low risk. A further 95 ongoing and 23 unpublished RCTs were identified for 42 of 116 devices (36·2 per cent), but many (64 of 116, 55·2 per cent) had no evidence from published, ongoing or unpublished RCTs. The highest stage of innovation according to the IDEAL Framework was stage 1 for 11 devices, stage 2a for 23 devices, stage 2b for one device and stage 3 for 33 devices. The remaining 48 devices had no relevant clinical evidence.

CONCLUSION

Only one in ten novel implantable devices available for use in gastrointestinal surgical practice is supported by high-quality RCT evidence.

Longitudinal analysis of reporting and quality of systematic reviews in high-impact surgical journals

BACKGROUND

The PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) Statement aims to optimize the reporting of systematic reviews. The performance of the PRISMA Statement in improving the reporting and quality of surgical systematic reviews remains unclear.

METHODS

Systematic reviews published in five high-impact surgical journals between 2007 and 2015 were identified from online archives. Manuscripts blinded to journal, publication year and authorship were assessed according to 27 reporting criteria described by the PRISMA Statement and scored using a validated quality appraisal tool (AMSTAR, Assessing the Methodological Quality of Systematic Reviews). Comparisons were made between studies published before (2007-2009) and after (2011-2015) its introduction. The relationship between reporting and study quality was measured using Spearman's rank test.

RESULTS

Of 281 eligible manuscripts, 80 were published before the PRISMA Statement and 201 afterwards. Most manuscripts (208) included a meta-analysis, with the remainder comprising a systematic review only. There was no meaningful change in median compliance with the PRISMA Statement (19 (i.q.r. 16-21) of 27 items before versus 19 (17-22) of 27 after introduction of PRISMA) despite achieving statistical significance (P = 0·042). Better reporting compliance was associated with higher methodological quality (r_s  = 0·70, P < 0·001).

CONCLUSION

The PRISMA Statement has had minimal impact on the reporting of surgical systematic reviews. Better compliance was associated with higher-quality methodology.

Pregnancy outcomes in cystic fibrosis: a 10-year experience from a UK centre

BACKGROUND

Cystic fibrosis manifests as a multisystem disease, despite this female fertility is relatively preserved with levels approaching that of the non-cystic fibrosis population. We reviewed pregnancies in cystic fibrosis patients over a 10-year period from a UK adult cystic fibrosis centre by considering maternal and fetal outcomes.

METHODS

We conducted a retrospective case-note review of pregnancies during 2003-2013 using respiratory and obstetric records.

RESULTS

We observed moderate falls in lung function immediately after delivery, which persisted at 12 months postpartum. We found that a decline in lung function at delivery was a marker for further decline in function during the subsequent postpartum period. We found baseline lung function was predictive of gestational age at delivery. We observed a high incidence of haemoptysis.

CONCLUSION

Consistent with current guidance we found pregnancy is feasible and well tolerated in the majority of patients with cystic fibrosis. There was a high incidence of haemoptysis, which warrants further study.

Analytical results for front pinning between an hexagonal pattern and a uniform state in pattern-formation systems

In pattern-forming systems, localized patterns are states of intermediate complexity between fully extended ordered patterns and completely irregular patterns. They are formed by stationary fronts enclosing an ordered pattern inside an homogeneous background. In two dimensions, the ordered pattern is most often hexagonal and the conditions for fronts to stabilize are still unknown. In this Letter, we show how the locking of these fronts depends on their orientation relative to the pattern. The theory rests on general asymptotic arguments valid when the spatial scale of the front is slow compared to that of the hexagonal pattern. Our analytical results are confirmed by numerical simulations with the Swift-Hohenberg equation, relevant to hydrodynamical and buckling instabilities, and a nonlinear optical cavity model.

The effects of cryoablation on renal cell carcinoma perfusion and glomerular filtration rate measured using dynamic contrast-enhanced MRI: a feasibility study

AIM

To assess the effect of cryoablation on renal cell carcinoma (RCC) perfusion and single kidney (SK) glomerular filtration rate (GFR) using dynamic contrast-enhanced (DCE) magnetic resonance imaging (MRI).

MATERIALS AND METHODS

Eighteen patients undergoing percutaneous cryoablation of a solitary RCC between August 2010 and November 2011 were evaluated with DCE-MRI immediately before and 1 month post-cryoablation. DCE-MRI data were acquired with 2 s temporal resolution in a coronal plane during the first pass of a 0.1 mmol/kg bolus dose of Gd-DOTA. Perfusion of the RCC (in ml/min/100 ml tissue) was estimated using a maximum slope technique. An index of SK GFR (SK-GFRi) was assessed using data acquired every 30 s for the following 3 min in the axial plane and analysed using Rutland-Patlak plots. This was compared to the GFR estimated by creatinine clearance (eGFR).

RESULTS

Perfusion in the zone of ablation decreased significantly (p<0.001) from a mean of 98.0 ± 37.5 ml/min/100 ml pre-cryoablation to 11.6 ± 4.1 ml/min/100 ml post-cryoablation; a mean decrease of 88.2%. Functional analysis was performed in seventeen patients. eGFR was underestimated by SK-GFRi which decreased significantly in tumour-bearing (-31.7%, p = 0.011), but not in contralateral kidneys (-4.4%, p = 0.14).

CONCLUSION

It is feasible to measure RCC perfusion pre- and post-cryoablation using DCE-MRI. The significant decrease within the zone of ablation suggests that this technique may be useful for assessment of treatment response. Further work is required to address the underestimation of eGFR by SK-GFRi and to validate the perfusion findings.

Bacteriophage therapy for refractory Pseudomonas aeruginosa urinary tract infection

We describe the success of adjunctive bacteriophage therapy for refractory Pseudomonas aeruginosa urinary tract infection in the context of bilateral ureteric stents and bladder ulceration, after repeated failure of antibiotics alone. No bacteriophage-resistant bacteria arose, and the kinetics of bacteriophage and bacteria in urine suggest self-sustaining and self-limiting infection.

Variable renewal rate and growth properties of cell populations in colon crypts

A nonlinear mathematical model is used to investigate the time evolution of the cell populations in colon crypts (stem, semidifferentiated and fully differentiated cells). To mimic pathological alteration of the biochemical pathways leading to abnormal proliferative activity of the population of semidifferentiated cells their renewal rate is assumed to be dependent on the population size. Then, the effects of such perturbation on the population dynamics are investigated theoretically. Using both theoretical methods and numerical simulations it is shown that the increase in the renewal rate of semidifferentiated cells strongly impacts the dynamical behavior of the cell populations.

Influence of boundaries on localized patterns

We analytically study the influence of boundaries on distant localized patterns generated by a Turing instability. To this end, we use the Swift-Hohenberg model with arbitrary boundary conditions. We find that the bifurcation diagram of these localized structures generally involves four homoclinic snaking branches, rather than two for infinite or periodic domains. Second, steady localized patterns only exist at discrete locations, and only at the center of the domain if their size exceeds a critical value. Third, reducing the domain size increases the pinning range.

NFKBIZ polymorphisms and susceptibility to pneumococcal disease in European and African populations

The proinflammatory transcription factor nuclear factor-kappaB (NF-kappaB) has a central role in host defence against pneumococcal disease. Both rare mutations and common polymorphisms in the NFKBIA gene encoding the NF-kappaB inhibitor, IkappaB-alpha, associate with susceptibility to bacterial disease, but the possible role of polymorphisms within the related IkappaB-zeta gene NFKBIZ in the development of invasive pneumococcal disease (IPD) has not been reported previously. To investigate this further, we examined the frequencies of 22 single-nucleotide polymorphisms spanning NFKBIZ in two case-control studies, comprising UK Caucasian (n=1008) and Kenyan (n=723) individuals. Nine polymorphisms within a single UK linkage disequilibrium (LD) block and all four polymorphisms within the equivalent, shorter Kenyan LD block displayed either a significant association with IPD or a trend towards association. For each polymorphism, heterozygosity was associated with protection from IPD when compared with the combined homozygous states (for example, for rs600718, Mantel-Haenszel 2 x 2 chi(2)=7.576, P=0.006, odds ratio (OR)=0.67, 95% confidence interval (95% CI) for OR: 0.51-0.88; for rs616597, Mantel-Haenszel 2 x 2 chi(2)=8.715, P=0.003, OR=0.65, 95% CI: 0.49-0.86). We conclude that multiple NFKBIZ polymorphisms associate with susceptibility to IPD in humans. The study of multiple populations may aid in fine mapping of associations within extensive regions of strong LD ('transethnic mapping').

An integrative computational model for intestinal tissue renewal

OBJECTIVES

The luminal surface of the gut is lined with a monolayer of epithelial cells that acts as a nutrient absorptive engine and protective barrier. To maintain its integrity and functionality, the epithelium is renewed every few days. Theoretical models are powerful tools that can be used to test hypotheses concerning the regulation of this renewal process, to investigate how its dysfunction can lead to loss of homeostasis and neoplasia, and to identify potential therapeutic interventions. Here we propose a new multiscale model for crypt dynamics that links phenomena occurring at the subcellular, cellular and tissue levels of organisation.

METHODS

At the subcellular level, deterministic models characterise molecular networks, such as cell-cycle control and Wnt signalling. The output of these models determines the behaviour of each epithelial cell in response to intra-, inter- and extracellular cues. The modular nature of the model enables us to easily modify individual assumptions and analyse their effects on the system as a whole.

RESULTS

We perform virtual microdissection and labelling-index experiments, evaluate the impact of various model extensions, obtain new insight into clonal expansion in the crypt, and compare our predictions with recent mitochondrial DNA mutation data.

CONCLUSIONS

We demonstrate that relaxing the assumption that stem-cell positions are fixed enables clonal expansion and niche succession to occur. We also predict that the presence of extracellular factors near the base of the crypt alone suffices to explain the observed spatial variation in nuclear beta-catenin levels along the crypt axis.

Interaction of spiral waves in the complex Ginzburg-Landau equation

Solutions of the general cubic complex Ginzburg-Landau equation comprising multiple spiral waves are considered, and laws of motion for the centers are derived. The direction of the motion changes from along the line of centers to perpendicular to the line of centers as the separation increases, with the strength of the interaction algebraic at small separations and exponentially small at large separations. The corresponding asymptotic wave number and frequency are also determined, which evolve slowly as the spirals move.

Positive replication and linkage disequilibrium mapping of the chromosome 21q22.1 malaria susceptibility locus

Four cytokine receptor genes are located on Chr21q22.11, encoding the alpha and beta subunits of the interferon-alpha receptor (IFNAR1 and IFNAR2), the beta subunit of the interleukin 10 receptor (IL10RB) and the second subunit of the interferon-gamma receptor (IFNGR2). We previously reported that two variants in IFNAR1 were associated with susceptibility to malaria in Gambians. We now present an extensive fine-scale mapping of the associated region utilizing 45 additional genetic markers obtained from public databases and by sequencing a 44 kb region in and around the IFNAR1 gene in 24 Gambian children (12 cases/12 controls). Within the IFNAR1 gene, a newly studied C --> G single-nucleotide polymorphism (IFNAR1 272354c-g) at position -576 relative to the transcription start was found to be more strongly associated with susceptibility to severe malaria. Association was observed in three populations: in Gambian (P=0.002), Kenyan (P=0.022) and Vietnamese (P=0.005) case-control studies. When all three studies were combined, using the Mantel-Haenszel test, the presence of IFNAR1 -576G was associated with a substantially elevated risk of severe malaria (N=2444, OR=1.38, 95% CI: 1.17-1.64; P=1.7 x 10(-4)). This study builds on previous work to further highlight the importance of the type-I interferon pathway in malaria susceptibility and illustrates the utility of typing SNPs within regions of high linkage disequilibrium in multiple populations to confirm initial positive associations.

Asymptotics of large bound states of localized structures

We analyze stationary fronts connecting uniform and periodic states emerging from a pattern-forming instability. The size of the resulting periodic domains cannot be predicted with weakly nonlinear methods. We show that what determine this size are exponentially small (but exponentially growing in space) terms. These can only be computed by going beyond all orders of the usual multiple-scale expansion. We apply the method to the Swift-Hohenberg equation and derive analytically a snaking bifurcation curve. At each fold of this bifurcation curve, a new pair of peaks is added to the periodic domain, which can thus be seen as a bound state of localized structures. Such scenarios have been reported with optical localized structures in nonlinear cavities and localized buckling.

A mathematical model for simultaneous spatio-temporal dynamics of calcium and inositol 1,4,5-trisphosphate in Madin-Darby canine kidney epithelial cells

The landmark paper by Hirose et al. (Hirose, K., Kadowaki, S., Tanabe, M., Takeshima, H., Iino, M., Science 284:1527-1530, 1999) presented experimental investigations to show that not only can calcium upregulate IP(3), but that it can also have an inhibitory effect on IP(3). In this paper, we present a preliminary model, which is consistent with these experiments. This model includes positive and negative feedback between calcium and IP(3) and is able to reproduce more precisely the data presented in Hirose et al. (Hirose, K., Kadowaki, S., Tanabe, M., Takeshima, H., Iino, M., Science 284:1527-1530, 1999). In the second part of the paper, the intracellular and intercellular calcium movement in Madin-Darby canine kidney epithelial cells is investigated. With the aid of the model we are able to identify the aspects of IP(3) and calcium signalling, which should be studied further experimentally before refining the model.

Interaction of two modulational instabilities in a semiconductor resonator

The interaction of two neighboring modulational instabilities in a coherently driven semiconductor cavity is investigated. First, an asymptotic reduction of the general equations is performed in the limit of a nearly vertical input-output characteristic. Next, a normal form is derived in the limit where the two instabilities are close to one other. An infinity of branches of periodic solutions are found to emerge from the unstable portion of the homogeneous branch. These branches have a nontrivial envelope in the bifurcation diagram that can either smoothly join the two instability points or form an isolated branch of solutions.

Edge diffraction of creeping rays

Explicit formulas are derived for waves modeled by the scalar two-dimensional Helmholtz equation for the field that is diffracted when surface creeping rays encounter an infinitely sharp edge. Both Neumann and Dirichlet boundary conditions are analyzed, and the diffracted field is found to be an order to magnitude smaller in the latter case.

Benefits of maternal corticosteroid therapy in infants weighing </=1000 grams at birth after preterm rupture of the amnion

OBJECTIVE

The aim of the study was to determine the effects of antenatal maternal corticosteroid treatment on selected neonatal outcomes in infants weighing </=1000 g at birth after preterm rupture of membranes.

STUDY DESIGN

In a 1-year (1992-1993) prospective observational study, the National Institute of Child Health and Human Development Maternal-Fetal Medicine Units Network collected outcome data for 766 infants who did not have a major fetal anomaly and who had a birth weight </=1000 g (378 were born after preterm rupture of membranes). Only fetuses deemed potentially viable by the obstetrician were included in our analysis. Selected neonatal outcomes were compared between mothers who did and did not receive antenatal corticosteroids. Logistic regression variables included birth weight, sex, race, amnionitis, tocolytic therapies, mode of delivery, and surfactant use.

RESULTS

Two hundred fourteen of the 378 infants whose mothers had preterm rupture of membranes were deemed potentially viable; 62 of these mothers received antenatal steroids and 152 did not. Groups were similar with respect to gestational age, birth weight, race, amnionitis, and delivery mode. Women who received antenatal steroids were more likely to have received tocolysis (P <.001). Univariate and regression analyses controlling for multiple confounders confirmed no neonatal benefits of maternal corticosteroid use.

CONCLUSIONS

Corticosteroid treatment in women with preterm rupture of membranes was of no apparent benefit to neonates weighing </=1000 g.

Production and distribution of endoglucanase, cellobiohydrolase, and beta-glucosidase components of the cellulolytic system of Volvariella volvacea, the edible straw mushroom

The edible straw mushroom, Volvariella volvacea, produces a multicomponent enzyme system consisting of endo-1,4-beta-glucanase, cellobiohydrolase, and beta-glucosidase for the conversion of cellulose to glucose. The highest levels of endoglucanase and cellobiohydrolase were recorded in cultures containing microcrystalline cellulose (Avicel) or filter paper, while lower but detectable levels of activity were also produced on carboxymethyl cellulose, cotton wool, xylitol, or salicin. Biochemical analyses of different culture fractions in cultures exhibiting peak enzyme production revealed that most of the endoglucase was present either in the culture filtrate (45.8% of the total) or associated with the insoluble pellet fraction remaining after centrifugation of homogenized mycelia (32.6%). Cellobiohydrolase exhibited a similar distribution pattern, with 58.9% of the total enzyme present in culture filtrates and 31.0% associated with the pellet fraction. Conversely, most beta-glucosidase activity (63.9% of the total) was present in extracts of fungal mycelia whereas only 9.4% was detected in culture filtrates. The endoglucanase and beta-glucosidase distribution patterns were confirmed by confocal laser scanning microscopy combined with immunolabelling. Endoglucanase was shown to be largely cell wall associated or located extracellularly, with the highest concentrations being present in a region 1 to 2 microm wide immediately adjacent to the outer surface of (and possibly including) the hyphal wall and extending 60 to 70 microm from the hyphal tip. Immunofluorescence patterns indicated little if any intracellular endoglucanase. Most beta-glucosidase was located intracellularly in the apical area extending 60 to 70 microm below the hyphal tip, although enzyme was also evident in the extracellular region extending approximately 15 microm all around the hyphal tip and trailing back along the length of the hypha. The regions of the hypha located some distance from the apical region appeared to be devoid of intracellular beta-glucosidase, and the enzyme appears to be associated almost exclusively with, or located on the outside surface of, the hyphal wall.

Varicella in pregnancy

Varicella-zoster virus may cause serious infection, particularly pneumonia, in adult women. Women of child-bearing age should be questioned about immunity to varicella preconceptually, and offered serological testing, and VARIVAX vaccine if indicated. All pregnant patients should be questioned about immunity to varicella during their first prenatal appointment. Susceptible patients should be counseled to avoid contact with individuals who have chickenpox. If exposure occurs, VZIG should be administered within 96 hours in an attempt to prevent maternal infection. Varicella embryopathy may occur as a result of maternal infection particularly in the first half of pregnancy with an incidence of 1% to 2%. Varicella of the newborn is a life-threatening illness that may occur when a newborn is delivered within 5 days of the onset of maternal illness or after postdelivery exposure to varicella. Susceptible neonates should receive VZIG. Acyclovir is active against the varicella-zoster virus, and treatment is indicated in seriously ill adults and neonates.

Randomized trial of single-dose versus multiple-dose cefotetan for the postpartum treatment of intrapartum chorioamnionitis

OBJECTIVE

Our purpose was to determine whether a single postpartum dose of a cephalosporin would effectively treat women with intrapartum chorioamnionitis and decrease the length of hospitalization.

STUDY DESIGN

After vaginal delivery consenting women who had received antibiotics for chorioamnionitis were assigned to postpartum treatment with either a single 2 gm intravenous dose of cefotetan or to cefotetan 2 gm given intravenously every 12 hours for a minimum of 48 hours. Chorioamnionitis was defined as an intrapartum temperature of > or = 100.4 degrees F and maternal or fetal tachycardia, maternal leukocytosis, or uterine tenderness. Patients were discharged when they had received their assigned dosage of cefotetan, were afebrile (temperature < 100.4 degrees F) and > or = 24 hours from delivery.

RESULTS

We studied 109 women (55 single dose, 54 multiple dose) with chorioamnionitis. The two groups were similar with regard to demographic and intrapartum characteristics. The median (range) interval from delivery to discharge was 24 hours lower in the single-dose group (33 [16 to 190] vs 57 [36 to 190] hours, p = 0.0001). The incidence of failed therapy was similar (single dose: 6/55, 11%, vs multiple dose: 2/54, 3.7%, p = 0.27).

CONCLUSIONS

A single postpartum dose of cefotetan appears to be effective treatment for intrapartum chorioamnionitis after a vaginal delivery and decreases the length of hospital stay.

Pregnancy outcomes following false-positive multiple marker screening tests

Pregnancy outcomes in women with a false-positive midtrimester multiple marker screening test (MMST) were reviewed. A genetic database was used to identify all women > or = age 30 who had a MMST at 15-20 weeks of gestation, a targeted ultrasound, and amniocentesis, and complete pregnancy outcome data. All patients with an abnormal fetal ultrasound (US) or karyotype were excluded. The incidence of adverse outcomes (defined as fetal death, preterm delivery, or a birth weight less than the 10th percentile for gestational age), in those women with a positive MMST (risk of Down's syndrome > or = 1:190) was compared to the incidence of adverse outcomes in control women with negative MMST. Chi-square analysis and Fisher's exact tests were used for comparisons as appropriate. Complete data was available from 1135 women. Seventy-seven percent were over age 35. Two hundred and forty-six women (22%) had a positive multiple marker test. No significant differences in outcomes were discovered after comparisons to controls: fetal death 1 of 246 (0.4%) versus 12 of 889 (1.3%), p = 0.32; preterm delivery 32 of 246 (13.0%) versus 147 of 889 (16.5%), p = 0.17; birth weight less than the 10th percentile, 9 of 246 (3.7%) versus 30 of 889 (3.4%), p = 0.83. Our data suggest that women > or = age 30 with a false-positive MMST and a normal midtrimester obstetrical sonogram are not at an increased risk for adverse pregnancy outcomes in later gestation.

One- versus two-layer closure of a low transverse cesarean: the next pregnancy

OBJECTIVE

To determine whether a low transverse cesarean closure method in one or two layers affects subsequent pregnancy outcome.

METHODS

In a prospective trial reported previously, 906 women were assigned randomly to either one- or two-layer uterine closure. One hundred sixty-four women had a subsequent pregnancy and delivery (18 weeks' gestation or longer) at our institution. Maternal and neonatal outcomes were ascertained by medical chart review and compared between the one- and two-layer closure groups.

RESULTS

Of the 164 subsequent deliveries, 83 had previous closure in one layer, whereas 81 had involved a two-layer closure. The demographic characteristics of these two groups were similar. Nineteen women (12%) underwent elective repeat cesareans without labor, and the remaining 145 experienced labor. Length of labor, mode of delivery, duration of hospital stay, gestation at delivery, and the incidences of uterine scar dehiscence, chorioamnionitis, postpartum metritis, hemorrhage, transfusion, and abnormal placentation did not differ significantly between the groups. Selected neonatal outcomes, including Apgar scores, cord pH, birth weight, and perinatal death, were similar between groups as well.

CONCLUSIONS

These findings suggest that the type of low transverse cesarean closure does not significantly affect the outcome of the next pregnancy.

Complications of midtrimester pregnancy termination: the effect of prior cesarean delivery

OBJECTIVE

Our purpose was to determine whether a prior cesarean delivery affects the incidence of complications in women having an indicated midtrimester medical pregnancy termination.

STUDY DESIGN

A retrospective review of women who underwent a midtrimester medical termination of pregnancy from January 1980 to July 1995 ascertained obstetric history, uterotonic agent(s), and the occurrence of uterine rupture, blood transfusion, or curettage. The frequencies of maternal complications were compared in women with and without a prior cesarean section.

RESULTS

Our study population included 606 women with a mean gestational age of 21.1 +/- 3.1 weeks and a mean maternal age of 26.3 +/- 7 years. Seventy-nine (13%) had undergone a prior cesarean section. There was no significant difference in the need for curettage between women with and without a prior cesarean section. However, there was an increased need for blood transfusions in women with a prior cesarean delivery (11.4% vs 5.3%, odds ratio 2.3, 95% confidence interval 1.1 to 5.0, p = 0.04). The incidence of uterine rupture was significantly higher among women with a prior cesarean (3.8% vs 0.2%, odds ratio 20.8, 95% confidence interval 14.1 to 104, p = 0.008).

CONCLUSION

Our data suggest that a prior cesarean section is a risk factor for uterine rupture and blood transfusion in women having a midtrimester pregnancy termination.

Epidermolysis bullosa simplex (Dowling-Meara type) is a genetic disease characterized by an abnormal keratin-filament network involving keratins K5 and K14

The distribution and morphology of tonofilament (TF) clumps were examined by light and electron microscopy in skin samples from a total of 17 patients with the Dowling-Meara (DM) form of epidermolysis bullosa simplex (EBS). TF clumps extending from the basal to the upper-spinous epidermal layer were seen in all lesional skin samples and in the majority of peri-lesional and non-lesional skin samples. TF clumps were also noted in adnexal epithelia, including outer hair root sheaths, sweat ducts, and sebaceous glands. Cultured keratinocytes from two patients also demonstrated characteristic TF clumps. All these epithelial cells have in common their expression of the keratin pair K5 and K14. Post-embedding immunogold electron microscopy using antibodies to K5, K14, and K10 showed similar expressed keratins in DM-EBS skin from four patients compared with normal skin, with K5 and K14 predominantly in the basal cell layer and K10 in the suprabasal layers. The clumped TF in DM-EBS samples were labeled strongly with anti-K5 and K14 antibodies in the basal and suprabasal layers. In contrast, the suprabasal clumps were only slightly reactive with anti-K10 antibodies and labeling was usually restricted to the periphery of the clumps. We conclude that DM-EBS is associated with an intrinsic abnormality of the keratin-filament network involving the K5 and K14 pair that is likely to result in impaired resistance of basal epidermal cells to external shearing forces, leading to the characteristic intraepidermal blisters. DM-EBS may become the first genetic skin disease to be recognized as having a specific keratin abnormality.

Sugars protect desmosome and corneosome glycoproteins from proteolysis

Adhesional glycoproteins of desmosomes possess asparagine-linked, complex oligosaccharide side chains. We investigated the potential of these sugars to protect the core proteins of desmosomes and corneosomes (modified stratum corneum desmosomes) against proteolysis. Isolated pig ear epidermis was exposed sequentially to individual hydrolases, and their effect monitored ultrastructurally. Two major steps were employed: (1) glycosidases, to remove stepwise the sugars in a typical complex oligosaccharide chain; and (2) proteolysis using both endopeptidases and an exopeptidase. Controls were exposed to the same sequence of buffers, but without enzymes. Proteases alone induced no major changes in desmosomes or corneosomes compared with controls. Glycosidases alone, or proteases followed by glycosidases, caused mild fragmentation of the desmosomal interspace, but no widening. However, dramatic changes occurred when glycosidase treatment was followed by proteolysis. The interspace of both desmosomes and corneosomes was extensively digested, and consequently widened, causing loose packing of the epidermis. These findings indicate that sugars are potentially anti-proteolytic in both desmosomes and corneosomes. Sugars may, therefore, be a factor in preventing premature desquamation, by protecting desmosomes and corneosomes against extracellular proteases derived from membrane-coating granules.

Is erythrokeratoderma one disorder? A clinical and ultrastructural study of two siblings

Two sisters with erythrokeratoderma are described. In the younger sister the clinical appearance corresponded to erythrokeratoderma variabilis (EKV), whereas in the older sister it corresponded to progressive symmetrical erythrokeratoderma (PSEK). Ultrastructural findings in both cases were identical. We suggest that EKV and PSEK are different manifestations of a single condition.

Lipids, proteins and corneocyte adhesion

Three factors were examined for their relative contribution to corneocyte cohesion in normal adult pig ear: (1) extracellular lipids derived from membrane-coating granules (MCG); (2) corneosomes (modified stratum corneum desmosomes); and (3) corneocyte covalently bound lipid envelopes. Cohesion strength of the outer stratum corneum was measured directly by cohesometry, then altered by removing MCG lipids with solvents of varying potency. Cohesion changes were related to degree of lipid removal and ultrastructural alterations. Trypsin was also used to see if proteolysis of corneosomes promoted squame shedding. Potent solvents increased cohesion in relation to the amount of MCG lipid extracted. Tighter cohesion was due to fusion of the outer leaflets from covalently bound lipid envelopes on adjacent corneocytes. However, lipid envelopes are unlikely to mediate normal stratum corneum cohesion since MCG lipids play a significant anti-cohesive role preventing their apposition. Mild solvents partially removed MCG lipids causing a slight decrease in cohesion compared with untreated samples. This suggests a minor cohesive role for MCG lipids, consistent with maintaining their barrier function. We believe that corneosomes are the major determinant of stratum corneum cohesiveness because, in untreated skin, both cohesion and the number of corneosomes increased from the surface towards the granular layer. Furthermore, corneosome digestion with trypsin induced superficial squame shedding.