AI-assisted capsule endoscopy reading in suspected small bowel bleeding: a multicentre prospective study

BACKGROUND

Capsule endoscopy reading is time consuming, and readers are required to maintain attention so as not to miss significant findings. Deep convolutional neural networks can recognise relevant findings, possibly exceeding human performances and reducing the reading time of capsule endoscopy. Our primary aim was to assess the non-inferiority of artificial intelligence (AI)-assisted reading versus standard reading for potentially small bowel bleeding lesions (high P2, moderate P1; Saurin classification) at per-patient analysis. The mean reading time in both reading modalities was evaluated among the secondary endpoints.

METHODS

Patients aged 18 years or older with suspected small bowel bleeding (with anaemia with or without melena or haematochezia, and negative bidirectional endoscopy) were prospectively enrolled at 14 European centres. Patients underwent small bowel capsule endoscopy with the Navicam SB system (Ankon, China), which is provided with a deep neural network-based AI system (ProScan) for automatic detection of lesions. Initial reading was performed in standard reading mode. Second blinded reading was performed with AI assistance (the AI operated a first-automated reading, and only AI-selected images were assessed by human readers). The primary endpoint was to assess the non-inferiority of AI-assisted reading versus standard reading in the detection (diagnostic yield) of potentially small bowel bleeding P1 and P2 lesions in a per-patient analysis. This study is registered with ClinicalTrials.gov, NCT04821349.

FINDINGS

From Feb 17, 2021 to Dec 29, 2021, 137 patients were prospectively enrolled. 133 patients were included in the final analysis (73 [55%] female, mean age 66·5 years [SD 14·4]; 112 [84%] completed capsule endoscopy). At per-patient analysis, the diagnostic yield of P1 and P2 lesions in AI-assisted reading (98 [73·7%] of 133 lesions) was non-inferior (p<0·0001) and superior (p=0·0213) to standard reading (82 [62·4%] of 133; 95% CI 3·6-19·0). Mean small bowel reading time was 33·7 min (SD 22·9) in standard reading and 3·8 min (3·3) in AI-assisted reading (p<0·0001).

INTERPRETATION

AI-assisted reading might provide more accurate and faster detection of clinically relevant small bowel bleeding lesions than standard reading.

FUNDING

ANKON Technologies, China and AnX Robotica, USA provided the NaviCam SB system.

Device-assisted enteroscopy performance measures in the United Kingdom: DEEP-UK quality improvement project

BACKGROUND

Device-assisted enteroscopy (DAE) has become a well-established diagnostic and therapeutic tool for the management of small-bowel pathology. We aimed to evaluate the performance measures for DAE across the UK against the quality benchmarks proposed by the European Society of Gastrointestinal Endoscopy (ESGE).

METHODS

We retrospectively collected data on patient demographics and DAE performance measures from electronic endoscopy records of consecutive patients who underwent DAE for diagnostic and therapeutic purposes across 12 enteroscopy centers in the UK between January 2017 and December 2022.

RESULTS

A total of 2005 DAE procedures were performed in 1663 patients (median age 60 years; 53% men). Almost all procedures (98.1%) were performed for appropriate indications. Double-balloon enteroscopy was used for most procedures (82.0%), followed by single-balloon enteroscopy (17.2%) and spiral enteroscopy (0.7%). The estimated depth of insertion was documented in 73.4% of procedures. The overall diagnostic yield was 70.0%. Therapeutic interventions were performed in 42.6% of procedures, with a success rate of 96.6%. Overall, 78.0% of detected lesions were marked with a tattoo. Patient comfort was significantly better with the use of deep sedation compared with conscious sedation (99.7% vs. 68.5%; P<0.001). Major adverse events occurred in only 0.6% of procedures.

CONCLUSIONS

Performance measures for DAE in the UK meet the ESGE quality benchmarks, with high diagnostic and therapeutic yields, and a low incidence of major adverse events. However, there is room for improvement in optimizing sedation practices, standardizing the depth of insertion documentation, and adopting marking techniques to aid in the follow-up of detected lesions.

Management of Small Bowel Neuroendocrine Tumours: 10 Years' Experience at a Tertiary Referral Centre

BACKGROUND

Neuroendocrine tumours (NET) arising from the small bowel are clinically challenging and are often diagnosed at advanced stages. Disease control with surgery alone can be demanding. Multimodal treatment concepts integrating surgery and non-surgical modalities could be of benefit.

METHOD

Retrospective review of consecutive adult patients with SB NET treated at Imperial College Healthcare NHS Trust between 1 January 2010 and 31 December 2019. Data regarding clinicopathological characteristics, treatments, and disease trajectory were extracted and summarised. Overall and progression/recurrence-free survival were estimated at 5 and 10 years.

RESULTS

154 patients were identified, with a median age of 64 years (range 33-87); 135/154 (87.7%) had stage III/IV disease at diagnosis. Surgery was used in 125 individuals (81.2%), typically with either segmental small bowel resection (60.8%) or right hemicolectomy (33.6%) and mesenteric lymphadenectomy for the primary tumour. Systemic and/or liver-directed therapies were used in 126 (81.8%); 60 (47.6%) had more than one line of non-surgical treatment. Median follow-up was 67.2 months (range 3.1-310.4); overall survival at 5 and 10 years was 91.0% (95% CI: 84.9-94.7%) and 82.5% (95% CI: 72.9-88.9%), respectively. Imaging-based median progression-free survival was 42.7 months (95% CI: 24.7 to 72.4); 5-year progression-free survival was 63.4% (95% CI: 55.0-70.6%); 10-year progression-free survival was 18.7% (95% CI: 12.4-26.1). Nineteen patients (12.3%) reached 10 years follow-up without disease recurrence and therefore were considered cured.

CONCLUSIONS

Most patients with SB NET present in a metastasised stage. Multimodal treatment concepts may be associated with excellent clinical outcomes. Future work should explore optimal approaches to treatment sequencing and patient selection.

Evaluation of a real-time computer-aided polyp detection system during screening colonoscopy: AI-DETECT study

BACKGROUND

Polyp detection and resection during colonoscopy significantly reduce long-term colorectal cancer risk. Computer-aided detection (CADe) may increase polyp identification but has undergone limited clinical evaluation. Our aim was to assess the effectiveness of CADe at colonoscopy within a bowel cancer screening program (BCSP).

METHODS

This prospective, randomized controlled trial involved all eight screening-accredited colonoscopists at an English National Health Service (NHS) BCSP center (February 2020 to December 2021). Patients were randomized to CADe or standard colonoscopy. Patients meeting NHS criteria for bowel cancer screening were included. The primary outcome of interest was polyp detection rate (PDR).

RESULTS

658 patients were invited and 44 were excluded. A total of 614 patients were randomized to CADe (n = 308) or standard colonoscopy (n = 306); 35 cases were excluded from the per-protocol analysis due to poor bowel preparation (n = 10), an incomplete procedure (n = 24), or a data issue (n = 1). Endocuff Vision was frequently used and evenly distributed (71.7 % CADe and 69.2 % standard). On intention-to-treat (ITT) analysis, there was a borderline significant difference in PDR (85.7 % vs. 79.7 %; P = 0.05) but no significant difference in adenoma detection rate (ADR; 71.4 % vs. 65.0 %; P = 0.09) for CADe vs. standard groups, respectively. On per-protocol analysis, no significant difference was observed in these rates. There was no significant difference in procedure times.

CONCLUSIONS

In high-performing colonoscopists in a BCSP who routinely used Endocuff Vision, CADe improved PDR but not ADR. CADe appeared to have limited benefit in a BCSP setting where procedures are performed by experienced colonoscopists.

Implementation of optical diagnosis with a "resect and discard" strategy in clinical practice: DISCARD3 study

BACKGROUND AND AIMS

Optical diagnosis (OD) of polyps can be performed with advanced endoscopic imaging. For high-confidence diagnoses, a "resect and discard" strategy could offer significant histopathology time and cost savings. The implementation threshold is a ≥90% OD-histology surveillance interval concordance. Here we assessed the OD learning curve and feasibility of a resect and discard strategy for ≤5-mm and <10-mm polyps in a bowel cancer screening setting.

METHODS

In this prospective feasibility study, 8 bowel cancer screening endoscopists completed a validated OD training module and performed procedures. All <10-mm consecutive polyps had white-light and narrow-band images taken and were given high- or low-confidence diagnoses until 120 high-confidence ≤5-mm polyp diagnoses had been performed. All polyps had standard histology. High-confidence OD errors underwent root-cause analysis. Histology and OD-derived surveillance intervals were calculated.

RESULTS

Of 565 invited patients, 525 patients were included. A total of 1560 <10-mm polyps underwent OD and were resected and retrieved (1329 ≤5 mm and 231 6-9 mm). There were no <10-mm polyp cancers. High-confidence OD was accurate in 81.5% of ≤5-mm and 92.8% of 6-9-mm polyps. Sensitivity for OD of a ≤5-mm adenoma was 93.0% with a positive predictive value of 90.8%. OD-histology surveillance interval concordance for ≤5-mm OD was 91.3% (209/229) for U.S. Multi-Society Task Force, 98.3% (225/229) for European Society of Gastrointestinal Endoscopy, and 98.7% (226/229) for British Society of Gastroenterology guidelines, respectively.

CONCLUSIONS

A resect and discard strategy for high-confidence ≤5-mm polyp OD in a group of bowel cancer screening colonoscopists is feasible and safe, with performance exceeding the 90% surveillance interval concordance required for implementation in clinical practice. (Clinical trial registration number: NCT04710693.).

Clinical characteristics with inflammation profiling of long COVID and association with 1-year recovery following hospitalisation in the UK: a prospective observational study

BACKGROUND

No effective pharmacological or non-pharmacological interventions exist for patients with long COVID. We aimed to describe recovery 1 year after hospital discharge for COVID-19, identify factors associated with patient-perceived recovery, and identify potential therapeutic targets by describing the underlying inflammatory profiles of the previously described recovery clusters at 5 months after hospital discharge.

METHODS

The Post-hospitalisation COVID-19 study (PHOSP-COVID) is a prospective, longitudinal cohort study recruiting adults (aged ≥18 years) discharged from hospital with COVID-19 across the UK. Recovery was assessed using patient-reported outcome measures, physical performance, and organ function at 5 months and 1 year after hospital discharge, and stratified by both patient-perceived recovery and recovery cluster. Hierarchical logistic regression modelling was performed for patient-perceived recovery at 1 year. Cluster analysis was done using the clustering large applications k-medoids approach using clinical outcomes at 5 months. Inflammatory protein profiling was analysed from plasma at the 5-month visit. This study is registered on the ISRCTN Registry, ISRCTN10980107, and recruitment is ongoing.

FINDINGS

2320 participants discharged from hospital between March 7, 2020, and April 18, 2021, were assessed at 5 months after discharge and 807 (32·7%) participants completed both the 5-month and 1-year visits. 279 (35·6%) of these 807 patients were women and 505 (64·4%) were men, with a mean age of 58·7 (SD 12·5) years, and 224 (27·8%) had received invasive mechanical ventilation (WHO class 7-9). The proportion of patients reporting full recovery was unchanged between 5 months (501 [25·5%] of 1965) and 1 year (232 [28·9%] of 804). Factors associated with being less likely to report full recovery at 1 year were female sex (odds ratio 0·68 [95% CI 0·46-0·99]), obesity (0·50 [0·34-0·74]) and invasive mechanical ventilation (0·42 [0·23-0·76]). Cluster analysis (n=1636) corroborated the previously reported four clusters: very severe, severe, moderate with cognitive impairment, and mild, relating to the severity of physical health, mental health, and cognitive impairment at 5 months. We found increased inflammatory mediators of tissue damage and repair in both the very severe and the moderate with cognitive impairment clusters compared with the mild cluster, including IL-6 concentration, which was increased in both comparisons (n=626 participants). We found a substantial deficit in median EQ-5D-5L utility index from before COVID-19 (retrospective assessment; 0·88 [IQR 0·74-1·00]), at 5 months (0·74 [0·64-0·88]) to 1 year (0·75 [0·62-0·88]), with minimal improvements across all outcome measures at 1 year after discharge in the whole cohort and within each of the four clusters.

INTERPRETATION

The sequelae of a hospital admission with COVID-19 were substantial 1 year after discharge across a range of health domains, with the minority in our cohort feeling fully recovered. Patient-perceived health-related quality of life was reduced at 1 year compared with before hospital admission. Systematic inflammation and obesity are potential treatable traits that warrant further investigation in clinical trials.

FUNDING

UK Research and Innovation and National Institute for Health Research.

Faecal haemoglobin concentration in adenoma, before and after polypectomy, approaches the ideal tumour marker

Background

Polypectomy may be performed at colonoscopy and then subsequent surveillance undertaken. It is thought that faecal haemoglobin concentration (f-Hb), estimated by quantitative faecal immunochemical tests (FIT), might be a useful tumour marker.

Methods

Consecutive patients enrolled in colonoscopy surveillance were approached at two hospitals. A specimen for FIT was provided before colonoscopy and, ideally after 3 weeks, a second FIT sample from those who had polypectomy. A single FIT system (OC-Sensor io, Eiken Chemical Co., Ltd) was used to generate f-Hb.

Results

1103 Patients were invited; 643 returned a FIT device (uptake: 58.3%). Four patients had known inflammatory bowel disease (IBD) and were excluded, leaving 639 (57.9%) with an age range of 25–90 years (median 64 years), 54.6% male. Of 593 patients who had a f-Hb result and completed colonoscopy, advanced neoplasia was found in 41 (6.9%); four colorectal cancer (CRC): 0.7% and 37 advanced adenoma (AA): 6.3%, and a further 127 (21.4%) had non-advanced adenoma (NAA). The median f-Hb was significantly greater in AA as compared to NAA; 6.0 versus 1.0 μg Hb/g faeces, p < 0.0001.134/164 (81.7%) of invited patients returned a second FIT device: 28 were patients with AA in whom median pre-polypectomy f-Hb was 19.2, falling to 3.5 μg Hb/g faeces post-polypectomy, p = 0.01, and 106 with NAA had median pre-polypectomy f-Hb 0.8 compared to 1.0 μg Hb/g faeces post-polypectomy, p = 0.96.

Conclusions

Quantitative FIT could provide a good tumour marker in post-polypectomy surveillance, reduce colonoscopy requirements and minimise potential risk to patients.

Different conformations of the German shepherd dog breed affect its posture and movement

The conformation of the German shepherd dog (GSD) varies considerably within the breed. These differences may result in large variation in the movement and limb loading and undesirable consequences to their musculoskeletal health. This study aimed to investigate the relationship between conformation and biomechanical measures in 60 GSDs. Full body kinematic and kinetic measures were computed from 3D motion capture and pressure data. The dogs were divided into groups based on their back slope and curvature. Correlation analysis and statistical differences between groups showed that GSDs with a greater back slope have a greater contact area in their forelimbs and place them closer together when standing (n = 60). During trot, the dogs with sloped back showed a greater vertical force in the forelimbs and a greater mid-thoracic flexion (n = 60). Unilateral differences were found in the stifle flexion, hock flexion and hock adduction, suggesting greater movement asymmetry with an increase in the back slope (n = 30). In conclusion, several biomechanical parameters are affected by the GSD's slope of the back and not by its curvature. Further studies are required to determine whether the variation in movement, posture and conformation within the breed relates to an increased susceptibility to musculoskeletal disorders.

Systematic review with meta-analysis: IBD-associated colonic dysplasia prognosis in the videoendoscopic era (1990 to present)

INTRODUCTION

The prognosis of dysplasia in patients with IBD is largely determined from observational studies from the pre-videoendoscopic era (pre-1990s) that does not reflect recent advances in endoscopic imaging and resection.

AIMS

To better understand the risk of synchronous colorectal cancer and metachronous advanced neoplasia (ie high-grade dysplasia or cancer) associated with dysplasia diagnosed in the videoendoscopic era, and to stratify risk according to a lesion's morphology, endoscopic resection status or whether it was incidentally detected on biopsy of macroscopically normal colonic mucosa (ie invisible).

METHODS

A systematic search of original articles published between 1990 and February 2020 was performed. Eligible studies reported on incidence of advanced neoplasia at follow-up colectomy or colonoscopy for IBD-dysplasia patients. Quantitative and qualitative analyses were performed.

RESULTS

Thirty-three studies were eligible for qualitative analysis (five for the meta-analysis). Pooled estimated proportions of incidental synchronous cancers found at colectomy performed for a pre-operative diagnosis of visible high-grade dysplasia, invisible high-grade dysplasia, visible low-grade dysplasia and invisible low-grade dysplasia were 13.7% (95% CI 0.0-54.1), 11.4% (95% CI 4.6-20.3), 2.7% (95% CI 0.0-7.1) and 2.4% (95% CI 0.0-8.5) respectively. The lowest incidences of metachronous advanced neoplasia, for dysplasia not managed with immediate colectomy but followed up with surveillance, tended to be reported by the studies where high definition imaging and/or chromoendoscopy was used and endoscopic resection of visible dysplasia was histologically confirmed.

CONCLUSIONS

The prognosis of IBD-dysplasia diagnosed in the videoendoscopic era appears to have been improved but the quality of evidence remains low. Larger, prospective studies are needed to guide management. PROSPERO registration no: CRD42019105736.

Faecal haemoglobin can define risk of colorectal neoplasia at surveillance colonoscopy in patients at increased risk of colorectal cancer

Background

Quantitative faecal immunochemical tests measure faecal haemoglobin concentration (f-Hb), which increases in the presence of colorectal neoplasia.

Objective

We examined the diagnostic accuracy of faecal immunochemical test (FIT)in patients at increased risk of colorectal cancer (CRC) attending for surveillance colonoscopy as per national guidelines.

Methods

A total of 1103 consecutive patients were prospectively invited to complete a FIT before their scheduled colonoscopy in two university hospitals in 2014– 2016. F-Hb was analysed on an OC-Sensor io automated analyser (Eiken Chemical Co., Ltd, Tokyo, Japan) with a limit of detection of 2 µg Hb/g faeces. The diagnostic accuracy of f-Hb for CRC and higher-risk adenoma was examined.

Results

A total of 643 patients returned a faecal test. After excluding 4 patients with known inflammatory bowel disease, 639 (57.9%) remained in the study: age range: 25–90 years (median: 64 years, interquartile range (IQR): 55–71): 54.6% male. Of 593 patients who also completed colonoscopy, 41 (6.9%) had advanced neoplasia (4 CRC, 37 higher-risk adenoma). Of the 238 patients (40.1%) who had detectable f-Hb, 31 (13.0%) had advanced neoplasia (2 CRC, 29 higher-risk adenoma) compared with 10 (2.8%) in those with undetectable f-Hb (2 CRC, 8 higher-risk adenoma). Detectable f-Hb gave negative predictive values of 99.4% for CRC and 97.2% for CRC plus higher-risk adenoma.

Conclusion

In patients at increased risk of CRC under colonoscopy surveillance, a test measuring faecal haemoglobin can provide an objective estimate of the risk of advanced neoplasia, and could enable tailored scheduling of colonoscopy.

Diagnosis and management of acute lower gastrointestinal bleeding: guidelines from the British Society of Gastroenterology

This is the first UK national guideline to concentrate on acute lower gastrointestinal bleeding (LGIB) and has been commissioned by the Clinical Services and Standards Committee of the British Society of Gastroenterology (BSG). The Guidelines Development Group consisted of representatives from the BSG Endoscopy Committee, the Association of Coloproctology of Great Britain and Ireland, the British Society of Interventional Radiology, the Royal College of Radiologists, NHS Blood and Transplant and a patient representative. A systematic search of the literature was undertaken and the quality of evidence and grading of recommendations appraised according to the GRADE(Grading of Recommendations Assessment, Development and Evaluation) methodology. These guidelines focus on the diagnosis and management of acute LGIB in adults, including methods of risk assessment and interventions to diagnose and treat bleeding (colonoscopy, computed tomography, mesenteric angiography, endoscopic therapy, embolisation and surgery). Recommendations are included on the management of patients who develop LGIB while receiving anticoagulants (including direct oral anticoagulants) or antiplatelet drugs. The appropriate use of blood transfusion is also discussed, including haemoglobin triggers and targets.

Cumulative burden of inflammation predicts colorectal neoplasia risk in ulcerative colitis: a large single-centre study

OBJECTIVE

Ulcerative colitis (UC) is a dynamic disease with its severity continuously changing over time. We hypothesised that the risk of colorectal neoplasia (CRN) in UC closely follows an actuarial accumulative inflammatory burden, which is inadequately represented by current risk stratification strategies.

DESIGN

This was a retrospective single-centre study. Patients with extensive UC who were under colonoscopic surveillance between 2003 and 2012 were studied. Each surveillance episode was scored for a severity of microscopic inflammation (0=no activity; 1=mild; 2=moderate; 3=severe activity). The cumulative inflammatory burden (CIB) was defined as sum of: average score between each pair of surveillance episodes multiplied by the surveillance interval in years. Potential predictors were correlated with CRN outcome using time-dependent Cox regression.

RESULTS

A total of 987 patients were followed for a median of 13 years (IQR, 9-18), 97 (9.8%) of whom developed CRN. Multivariate analysis showed that the CIB was significantly associated with CRN development (HR, 2.1 per 10-unit increase in CIB (equivalent of 10, 5 or 3.3 years of continuous mild, moderate or severe active microscopic inflammation); 95% CI 1.4 to 3.0; P<0.001). Reflecting this, while inflammation severity based on the most recent colonoscopy alone was not significant (HR, 0.9 per-1-unit increase in severity; 95% CI 0.7 to 1.2; P=0.5), a mean severity score calculated from all colonoscopies performed in preceding 5 years was significantly associated with CRN risk (HR, 2.2 per-1-unit increase; 95% CI 1.6 to 3.1; P<0.001).

CONCLUSION

The risk of CRN in UC is significantly associated with accumulative inflammatory burden. An accurate CRN risk stratification should involve assessment of multiple surveillance episodes to take this into account.

Allelopathic interference of alfalfa (Medicago sativa L.) genotypes to annual ryegrass (Lolium rigidum)

Alfalfa (Medicago sativa L.) genotypes at varying densities were investigated for allelopathic impact using annual ryegrass (Lolium rigidum) as the target species in a laboratory bioassay. Three densities (15, 30, and 50 seedlings/beaker) and 40 alfalfa genotypes were evaluated by the equal compartment agar method (ECAM). Alfalfa genotypes displayed a range of allelopathic interference in ryegrass seedlings, reducing root length from 5 to 65%. The growth of ryegrass decreased in response to increasing density of alfalfa seedlings. At the lowest density, Q75 and Titan9 were the least allelopathic genotypes. An overall inhibition index was calculated to rank each alfalfa genotype. Reduction in seed germination of annual ryegrass occurred in the presence of several alfalfa genotypes including Force 10, Haymaster7 and SARDI Five. A comprehensive metabolomic analysis using Quadruple Time of Flight (Q-TOF), was conducted to compare six alfalfa genotypes. Variation in chemical compounds was found between alfalfa root extracts and exudates and also between genotypes. Further individual compound assessments and quantitative study at greater chemical concentrations are needed to clarify the allelopathic activity. Considerable genetic variation exists among alfalfa genotypes for allelopathic activity creating the opportunity for its use in weed suppression through selection.

Endoscopic Dilatation of Crohn's Anastomotic Strictures is Effective in the Long Term, and Escalation of Medical Therapy Improves Outcomes in the Biologic Era

BACKGROUND AND AIMS

To investigate the long-term efficacy of endoscopic dilatation of Crohn's anastomotic strictures and to identify risk and protective factors associated with the need for repeat dilatation or surgery.

METHODS

A total of 54 patients who had endoscopic balloon dilatations for anastomotic Crohn's strictures between 2004 and 2009, with follow-up until June 2014, were identified from a single tertiary center. The primary end points were repeat dilatation or surgical resection, and the impact of radiology, medical therapy, and endoscopic data on these outcomes was analysed with Cox proportional hazards analysis.

RESULTS

A total of 151 dilatations were performed on patients with a median age of 52 years [interquartile range (IQR), 46-62 years]. The median duration from the first to the second dilatation was 6 years (IQR, 5-7 years). The median disease duration was 28 years (IQR, 19-32 years). At endoscopy, disease activity was reported in 50/54 (92%) cases, with a median Rutgeerts grading of i2 (range, i0-i4). A median of two (IQR 1-9) dilatations was required, with a time to repeat dilatation of 23 months (IQR 7.2-56.9). Escalation of medical therapy was adopted in 22/54 patients (41% of the study population). On multivariate analysis, only combination therapy (anti-TNFα and immunomodulator) was significantly associated with the (decreased) need for repeated dilatation [hazard ratio (HR) 0.23; 95% CI, 0.07-0.67; p = 0.01]. Anastomotic resections were performed in 10 (18%) patients, with a Rutgeerts score of i4 at initial endoscopic balloon dilatation being associated with this outcome (HR 4.55; 95% CI 1.08-19.29; p = 0.04) on multivariate analysis.

CONCLUSION

Endoscopic balloon dilatation of Crohn's anastomotic strictures is safe and effective in the long term. We demonstrate that active disease predicts for future surgery, while escalation of medical therapy may decrease the need for repeat dilatation.

Quantification of crypt and stem cell evolution in the normal and neoplastic human colon

Human intestinal stem cell and crypt dynamics remain poorly characterized because transgenic lineage-tracing methods are impractical in humans. Here, we have circumvented this problem by quantitatively using somatic mtDNA mutations to trace clonal lineages. By analyzing clonal imprints on the walls of colonic crypts, we show that human intestinal stem cells conform to one-dimensional neutral drift dynamics with a "functional" stem cell number of five to six in both normal patients and individuals with familial adenomatous polyposis (germline APC(-/+)). Furthermore, we show that, in adenomatous crypts (APC(-/-)), there is a proportionate increase in both functional stem cell number and the loss/replacement rate. Finally, by analyzing fields of mtDNA mutant crypts, we show that a normal colon crypt divides around once every 30-40 years, and the division rate is increased in adenomas by at least an order of magnitude. These data provide in vivo quantification of human intestinal stem cell and crypt dynamics.

Lineage tracing reveals multipotent stem cells maintain human adenomas and the pattern of clonal expansion in tumor evolution

The genetic and morphological development of colorectal cancer is a paradigm for tumorigenesis. However, the dynamics of clonal evolution underpinning carcinogenesis remain poorly understood. Here we identify multipotential stem cells within human colorectal adenomas and use methylation patterns of nonexpressed genes to characterize clonal evolution. Numerous individual crypts from six colonic adenomas and a hyperplastic polyp were microdissected and characterized for genetic lesions. Clones deficient in cytochrome c oxidase (CCO(-)) were identified by histochemical staining followed by mtDNA sequencing. Topographical maps of clone locations were constructed using a combination of these data. Multilineage differentiation within clones was demonstrated by immunofluorescence. Methylation patterns of adenomatous crypts were determined by clonal bisulphite sequencing; methylation pattern diversity was compared with a mathematical model to infer to clonal dynamics. Individual adenomatous crypts were clonal for mtDNA mutations and contained both mucin-secreting and neuroendocrine cells, demonstrating that the crypt contained a multipotent stem cell. The intracrypt methylation pattern was consistent with the crypts containing multiple competing stem cells. Adenomas were epigenetically diverse populations, suggesting that they were relatively mitotically old populations. Intratumor clones typically showed less diversity in methylation pattern than the tumor as a whole. Mathematical modeling suggested that recent clonal sweeps encompassing the whole adenoma had not occurred. Adenomatous crypts within human tumors contain actively dividing stem cells. Adenomas appeared to be relatively mitotically old populations, pocketed with occasional newly generated subclones that were the result of recent rapid clonal expansion. Relative stasis and occasional rapid subclone growth may characterize colorectal tumorigenesis.

Barrett's metaplasia glands are clonal, contain multiple stem cells and share a common squamous progenitor

BACKGROUND

Little is known about the stem cell organisation of the normal oesophagus or Barrett's metaplastic oesophagus. Using non-pathogenic mitochondrial DNA mutations as clonal markers, the authors reveal the stem cell organisation of the human squamous oesophagus and of Barrett's metaplasia and determine the mechanism of clonal expansion of mutations.

METHODS

Mutated cells were identified using enzyme histochemistry to detect activity of cytochrome c oxidase (CCO). CCO-deficient cells were laser-captured and mutations confirmed by PCR sequencing. Cell lineages were identified using immunohistochemistry.

RESULTS

The normal squamous oesophagus contained CCO-deficient patches varying in size from around 30 μm up to about 1 mm. These patches were clonal as each area within a CCO-deficient patch contained an identical mitochondrial DNA mutation. In Barrett's metaplasia partially CCO-deficient glands indicate that glands are maintained by multiple stem cells. Wholly mutated Barrett's metaplasia glands containing all the expected differentiated cell lineages were seen, demonstrating multilineage differentiation from a clonal population of Barrett's metaplasia stem cells. Patches of clonally mutated Barrett's metaplasia glands were observed, indicating glands can divide to form patches. In one patient, both the regenerating squamous epithelium and the underlying glandular tissue shared a clonal mutation, indicating that they are derived from a common progenitor cell.

CONCLUSION

In normal oesophageal squamous epithelium, a single stem cell clone can populate large areas of epithelium. Barrett's metaplasia glands are clonal units, contain multiple multipotential stem cells and most likely divide by fission. Furthermore, a single cell of origin can give rise to both squamous and glandular epithelium suggesting oesophageal plasticity.

Use of methylation patterns to determine expansion of stem cell clones in human colon tissue

BACKGROUND & AIMS

It is a challenge to determine the dynamics of stem cells within human epithelial tissues such as colonic crypts. By tracking methylation patterns of nonexpressed genes, we have been able to determine how rapidly individual stem cells became dominant within a human colonic crypt. We also analyzed methylation patterns to study clonal expansion of entire crypts via crypt fission.

METHODS

Colonic mucosa was obtained from 9 patients who received surgery for colorectal cancer. The methylation patterns of Cardiac-specific homeobox, Myoblast determination protein 1, and Biglycan were examined within clonal cell populations, comprising either part of, or multiple adjacent, normal human colonic crypts. Clonality was demonstrated by following cytochrome c oxidase-deficient (CCO⁻) cells that shared an identical somatic point mutation in mitochondrial DNA.

RESULTS

Methylation pattern diversity among CCO⁻ clones that occupied only part of a crypt was proportional to clone size; this allowed us to determine rates of clonal expansion. Analysis indicated a slow rate of niche succession within the crypt. The 2 arms of bifurcating crypts had distinct methylation patterns, indicating that fission can disrupt epigenetic records of crypt ancestry. Adjacent clonal CCO⁻ crypts usually had methylation patterns as dissimilar to one another as methylation patterns of 2 unrelated crypts. Mathematical models indicated that stem cell dynamics and epigenetic drift could account for observed dissimilarities in methylation patterns.

CONCLUSIONS

Methylation patterns can be analyzed to determine the rates of recent clonal expansion of stem cells, but determination of clonality over many decades is restricted by epigenetic drift. We developed a technique to follow changes in intestinal stem cell dynamics in human epithelial tissues that might be used to study premalignant disease.

Stem cells and inflammation in the intestine

Knowledge of stem cell biology in the intestine is increasing exponentially and it is one of the current hot topics 'of the day'. Yet it is only recently that molecules such as Lgr5 and Bmi1 have been shown to reliably mark stem cells and have revealed the stem cell location throughout the murine gastrointestinal tract. However, there is a scarcity of meaningful work within their human counterpart. Nevertheless, recent studies have demonstrated the processes of niche succession, where one stem cell takes over the entire population of stem cells within a crypt; and monoclonal conversion, whereby the entire crypt becomes a clonal population of cells, are present in the human crypt. This work has also shown how crypts themselves divide and expand in the human colon.

Evaporative cooling of antiprotons to cryogenic temperatures

We report the application of evaporative cooling to clouds of trapped antiprotons, resulting in plasmas with measured temperature as low as 9 K. We have modeled the evaporation process for charged particles using appropriate rate equations. Good agreement between experiment and theory is observed, permitting prediction of cooling efficiency in future experiments. The technique opens up new possibilities for cooling of trapped ions and is of particular interest in antiproton physics, where a precise CPT test on trapped antihydrogen is a long-standing goal.

The histogenesis of regenerative nodules in human liver cirrhosis

Here, we investigate the clonality and cells of origin of regenerative nodules in human liver cirrhosis using mitochondrial DNA (mtDNA) mutations as markers of clonal expansion. Mutated cells are identified phenotypically by deficiency in the entirely mtDNA encoded cytochrome c oxidase (CCO) enzyme by histochemical and immunohistochemical methods. Nodules were classified as either CCO-deficient or CCO-positive, and among 526 nodules from 10 cases, 18% were homogeneously CCO-deficient, whereas only 3% had a mixed phenotype. From frozen sections, hepatocytes were laser-capture microdissected from several sites within individual CCO-deficient nodules. Mutations were identified by polymerase chain reaction sequencing of the entire mtDNA genome. In all cases except for one, the nodules were monoclonal in nature, possessing up to four common mutations in all hepatocytes in a given nodule. Moreover, the identification of identical mutations in hepatic progenitor cells abutting CCO-deficient nodules proves that nodules can have their origins from such cells.

CONCLUSION

These data support a novel pathway for the monoclonal derivation of human cirrhotic regenerative nodules from hepatic progenitor cells.

Colonic crypt organization and tumorigenesis

An appreciation of colonic crypt organization has become essential to any understanding of tumorigenesis in the colon. Intestinal crypts house tissue-specific, multipotential stem cells, which are located in the niche at the base of the intestinal crypt and are capable of regenerating all intestinal cell types. Recent advances in our understanding of crypt biology, including how mutations in stem cells become fixed and expand within the epithelium, has led to new theories on the origins of colonic adenomas and cancers.

cDNA array analysis of pineal gene expression reveals circadian rhythmicity of the dominant negative helix-loop-helix protein-encoding gene, Id-1

The pineal gland is a major output of the endogenous vertebrate circadian clock, with melatonin serving as the output signal. In many species, elevated nocturnal melatonin production is associated with changes in pineal gene expression. In the current study, cDNA array analysis was used in an attempt to identify additional genes that exhibit day/night differential expression in the rat pineal gland. This revealed 38 candidate genes, including Id-1 (inhibitor of DNA binding and differentiation). Id-1 encodes a helix-loop-helix (HLH) protein that lacks a basic DNA binding domain and could affect pineal physiology via a dominant negative trans-acting regulatory activity. For this reason Id-1 was selected for further analysis. Id-1 was expressed in a major population of pineal cells and the Id-1 protein was associated with a nuclear complex. The levels of Id-1 mRNA and protein exhibit approximately six-fold day/night rhythms. In contrast, the related genes Id-2 and Id-3 do not exhibit marked day/night differences in pineal expression. Rhythmic Id-1 expression is primarily limited to a C-terminally extended splice variant of Id-1, which would restrict the functional output of the rhythm to protein binding partners of this isoform of Id-1. Our findings add to the body of evidence indicating that transcriptional regulators play a role in neuroendocrine rhythms, and extend this by introducing the concept of a dominant negative HLH involvement. The rhythm in Id-1 in the pineal gland provides an experimental opportunity to identify Id-1-binding partners which may also be involved in Id-1 activity in other functional contexts.

Optimisation of methods for selecting candidate genes from cDNA array screens: application to rat brain punches and pineal

DNA arrays are potentially powerful experimental tools within neuroscience but application of this technology to in vivo paradigms may, in practice, be limited by the sensitivity of transcript detection and inter-screen variation. Here we describe the use of brain punch micro-sampling, used in combination with commercially available cDNA arrays, for profiling brain gene expression in a mutant strain of rat (GAERS model of absence epilepsy). Furthermore, we describe a multi-step optimisation of analysis methods which provides for improved sensitivity and absence of bias in the selection of candidate genes which may be differentially expressed in the mutant. Our method has been validated through application to a second paradigm, rhythmic gene expression in the rat pineal gland. Our experimental design, and analysis method should therefore be generally applicable to subtle discriminations of transcript abundance within discrete brain areas.

Tissue-specific transgenic knockdown of Fos-related antigen 2 (Fra-2) expression mediated by dominant negative Fra-2

Fos-related antigen 2 (Fra-2) is a member of the Fos family of immediate-early genes, most of which are rapidly induced by second messengers. All members of this family act by binding to AP-1 sites as heterodimeric complexes with other proteins. However, each appears to have a distinct role. The role and biology of Fra-2 are less well understood than those of its relatives c-Fos, Fra-1, and FosB; moreover, Fra-2 target genes remain largely unknown, as does the basis of its selective effects on transcriptional activity. To pursue these issues, we created a transgenic rat line (NATDNF2) in which a dominant negative fra-2 (DNF2) gene is strongly expressed in the pineal gland; tissue selectivity was achieved by putting the DNF2 gene under the control of the rat arylalkylamine N-acetyltransferase (AANAT) regulatory region, which targets gene expression to a very restricted set of tissues (pineal gland >> retina). Expression of AANAT is normally turned on after the onset of darkness in the rat; as a result, pineal DNF2 expression occurs only at night. This was associated with marked suppression of the nocturnal increase in fra-2 mRNA and protein levels, indicating that DNF2 expression inhibits downstream effects of Fra-2, including the maintenance of high levels of fra-2 gene expression. Analysis of 1,190 genes in the NATDNF2 pineal gland, including the AANAT gene, identified two whose expression is strongly linked to fra-2 expression: the genes encoding type II iodothyronine deiodinase and nectadrin (CD24).

Reversal of metabolic block in glycolysis by enzyme replacement in triosephosphate isomerase-deficient cells

Inherited deficiency of the housekeeping enzyme triosephosphate isomerase (TPI) is the most severe clinical disorder of glycolysis. Homozygotes manifest congenital hemolytic anemia and progressive neuromuscular impairment, which in most cases pursues an inexorable course with fatal outcome in early childhood. No effective therapy is available. Hitherto specific enzyme replacement has not been attempted in disorders of glycolysis. Primary skeletal muscle myoblasts and Epstein-Barr virus (EBV)-transformed lymphoblastoid cell lines generated from homozygous TPI-deficient patients were cultured in the presence of exogenous enzyme or cocultured with human K562 erythroleukemia cells as an exogenous source of TPI. Uptake of active enzyme by TPI-deficient cells resulted in reversal of intracellular substrate accumulation, with a reduction in dihydroxyacetone phosphate (DHAP) concentration to levels seen in TPI-competent cells. Evidence of successful metabolic correction of TPI deficiency in vitro establishes the feasibility of enzyme replacement therapy, and has important implications for the potential role of allogeneic bone marrow transplantation and gene therapy as a means of sustained delivery of functional enzyme in vivo.

Ancestral origin of variation in the triosephosphate isomerase gene promoter

A high frequency of nucleotide substitutions -5A/G, -8G/A, -24T/G in the triosephosphate isomerase (TPI) gene promoter has been demonstrated in African-Americans. The biological significance of these promoter variants, two of which, -8G/A and -24T/G, occur within regulatory elements essential for transcription, is controversial. The geographical distribution and frequency of allelic variation in the TPI promoter was determined in 378 unrelated normal subjects from sub-Saharan African (n = 103), Caribbean (n = 26), Northern European (n = 57), Mediterranean (n = 55), Middle Eastern (n = 42), Asian Indian (n = 48) and Oriental (n = 47) populations. Five haplotypes were identified: the common haplotype, -5A-8G-24T, -5G, -8A, -5G-8A, and -5G-8A-24G. All, with the exception of the -8A haplotype, were present in geographically dispersed populations. The -5G allele, which was found at varying frequency in all groups, has attained high frequency in the African, Caribbean and Oriental populations. Phylogenetic comparison suggests this may represent the ancestral promoter haplotype. Homozygosity for the -5G-8A haplotype identified in four subjects confirms that these variants are not responsible for a null allele as formerly postulated. Linkage disequilibrium between related TPI promoter haplotypes, -5G, -5G-8A and -5G-8A-24G, and a single nucleotide polymorphism at nt2262 of the TPI gene supports a single ancestral origin for these mutations which precedes the separation of African and non-African populations.

The consequence of nucleotide substitutions in the triosephosphate isomerase (TPI) gene promoter

Mutations at -5A-->G, -8-->GA within the cap proximal element (CPE), and -24T-->G within the TATA box of the triosephosphate isomerase (TPI) gene promoter have been identified in populations with a wide geographical distribution. These mutations lie within, or in close proximity to, known cis-active elements in the TPI gene promoter. To determine the functional significance of mutation at these sites, which remains controversial, their effect on the expression of erythrocyte TPI enzyme activity was studied in 110 healthy unrelated subjects. The -5G mutation did not alter erythrocyte TPI level, whereas the -8A mutation was accompanied by a significant reduction in enzyme activity to around 90% and 76% of normal erythrocyte TPI activity in heterozygotes and homozygotes, respectively. The -8A -24G genotype was associated with 75% of normal TPI activity in a heterozygote studied, implying that substitution of G at position -24 within the canonical TATA motif causes an additive decrease in TPI gene transcription in erythroid cells. A DNA-protein complex of 125kDa which was competitively blocked by specific unlabelled oligomers was demonstrated at the CPE and TATA box by electrophoretic mobility shift analysis. These findings provide direct evidence that TPI promoter mutations are linked to a reduction of TPI enzyme activity in vivo.

Regulation of triosephosphate isomerase (TPI) gene expression in TPI deficient lymphoblastoid cells

The metabolic defect of triosephosphate isomerase (TPI) deficiency is reversible in deficient lymphoblastoid cells when cultured in the presence of human K562 erythroleukemia cells or plasma as exogenous source of functional enzyme. However, plasma contains a variety of undefined biological response modifiers whose effects on TPI gene expression are unknown. In the present study, TPI deficient lymphoblastoid cells were cultured in serum-free medium for 24 h (controls) and stimulated with fresh frozen plasma (FFP) at final concentrations of 20, 40, and 60% for 9 h. Changes in TPI mRNA expression were monitored by slot and Northern blot hybridisations using a specific human TPI cDNA probe. For equivalent loading of total RNA, TPI mRNA expression in FFP-treated lymphoblastoid cells exceeded that for controls by on average 20-fold. Additional studies with the transcription inhibitor, actinomycin D, revealed a rapid degradation of TPI mRNA in controls compared to FFP-treated cells, indicating that the stability of the TPI transcript was affected by plasma. These data suggest that functional or regulatory elements within the TPI gene promoter can be modulated by biological response modifiers. An understanding of the transcriptional control of TPI may provide useful insights into the development of gene therapy strategies for TPI deficiency.

The feasibility of replacement therapy for inherited disorder of glycolysis: triosephosphate isomerase deficiency (review)

Triosephosphate isomerase (TPI, EC 5.3.1.1) is an ubiquitously expressed enzyme that catalyses the interconversion of dihydroxyacetone phosphate (DHAP) and glyceraldehyde-3-phosphate in the energy-generating glycolytic pathway. Inherited defects in the TPI gene are characterised biochemically by markedly reduced TPI enzyme activity in all tissues resulting in metabolic block in glycolysis, with accumulating DHAP particularly in red cells. Clinical TPI deficiency is a rare autosomal recessive multi-system disorder characterised by non-spherocytic haemolytic anaemia, recurrent infections, cardiomyopathy, severe and fatal neuromuscular dysfunctions. Reviews of current literature show that after 30 years since TPI deficiency was first described, the disease still remains without effective therapy. However, several potential therapeutic strategies exist for the treatment of inherited metabolic disorders such as TPI deficiency. Development of an effective therapy for TPI deficiency presents a fascinating and formidable challenge for basic laboratory and clinical research. The major aim of this overview is to discuss the current knowledge of TPI deficiency with special emphasis on research efforts directed towards reversing the metabolic effects of the disorder.

Metabolic correction of triose phosphate isomerase deficiency in vitro by complementation

Inherited deficiency of triose phosphate isomerase (TPI), the enzyme that catalyses the interconversion of dihydroxyacetone phosphate (DHAP) and glyceraldehyde-3-phosphate, is characterised by an accumulation of intracellular DHAP and markedly reduced enzyme activity in cells and tissues, resulting in progressive, usually fatal neuromuscular dysfunction. Since specific enzyme replacement for TPI deficiency is not currently available, the secretion and recapture of the missing enzyme was investigated in a co-culture model comprising K562 human erythroleukaemia cells and lymphoblastoid cells taken from a TPI deficient patient. A sevenfold reduction in intracellular DHAP with concomitant increase in intracellular TPI activity from 7.25 +/- 0.1 to 197.2 +/- 10 units/mg protein was achieved for co-cultured lymphoblastoid cells. These novel results confirm the existence of a transport mechanism which permits transfer of active TPI from K562 cells to deficient cells, and may have important implications for developing different therapeutic approaches for TPI deficiency and other metabolic disorders of glycolysis.

Familial exudative vitreoretinopathy linked to D11S533 in a large Asian family with consanguinity

Familial exudative vitreoretinopathy (FEVR) is a disorder characterised by peripheral retinal vascularisation with subsequent traction of retinal vessels and detachment. Recently, autosomal dominant FEVR (ad FEVR) has been mapped to 11q13 by linkage in four northern European families. We describe a large consanguineous Asian family in which the severity of the proband's eye disease suggested homozygosity for a disease allele. Thirty family members were assessed by ophthalmological examination and fluorescein angiography. Thirteen had unequivocal features of FEVR. A further two were classified as unknown. Two point linkage analysis for DIIS533 and FEVR generated a lod score of 5.55 at a recombination fraction of 0.00. This supports autosomal dominant inheritance and demonstrates genetic homogeneity for the ad FEVR disease locus. The severely affected proband was heterozygous for alleles at this closely linked locus. Other causes, including non-genetic factors, should be considered to explain the extreme variability characteristic of ad FEVR.

Right atrial thrombus formation following central venous dialysis catheter placement

Silicone rubber central venous dialysis catheters are used to provide vascular access in acute renal failure patients and in chronic dialysis patients in whom conventional vascular access cannot be achieved or maintained. The use of these catheters is not without hazard. The first reported case of right atrial thrombus formation associated with the use of a double lumen silicone rubber central hemodialysis catheter is described. This patient's course points out another potential complication of this type of vascular access and emphasizes the importance of removing such catheters in a timely fashion when they are no longer required for dialysis.