Artificial Intelligence Tools for the Diagnosis of Eosinophilic Esophagitis in Adults Reporting Dysphagia: Development, External Validation, and Software Creation for Point-of-Care Use

BACKGROUND

Despite increased awareness of eosinophilic esophagitis (EoE), the diagnostic delay has remained stable over the past 3 decades. There is a need to improve the diagnostic performance and optimize resources allocation in the setting of EoE.

OBJECTIVE

We developed and validated 2 point-of-care machine learning (ML) tools to predict a diagnosis of EoE before histology results during office visits.

METHODS

We conducted a multicenter study in 3 European tertiary referral centers for EoE. We built predictive ML models using retrospectively extracted clinical and esophagogastroduodenoscopy (EGDS) data collected from 273 EoE and 55 non-EoE dysphagia patients. We validated the models on an independent cohort of 93 consecutive patients with dysphagia undergoing EGDS with biopsies at 2 different centers. Models' performance was assessed by area under the curve (AUC), sensitivity, specificity, and positive and negative predictive values (PPV and NPV). The models were integrated into a point-of-care software package.

RESULTS

The model trained on clinical data alone showed an AUC of 0.90 and a sensitivity, specificity, PPV, and NPV of 0.90, 0.75, 0.80, and 0.87, respectively, for the diagnosis of EoE in the external validation cohort. The model trained on a combination of clinical and endoscopic data showed an AUC of 0.94, and a sensitivity, specificity, PPV, and NPV of 0.94, 0.68, 0.77, and 0.91, respectively, in the external validation cohort.

CONCLUSION

Our software-integrated models (https://webapplicationing.shinyapps.io/PointOfCare-EoE/) can be used at point-of-care to improve the diagnostic workup of EoE and optimize resources allocation.

Six-Food Elimination Diet Is Less Effective During Pollen Season in Adults With Eosinophilic Esophagitis Sensitized to Pollens

INTRODUCTION

The role of inhaled and swallowed aeroallergens in treatment outcomes of adult patients with eosinophilic esophagitis (EoE) is unclear. We hypothesized that the pollen season contributes to the failure of the 6-food elimination diet (SFED) in EoE.

METHODS

We compared outcomes of patients with EoE who underwent SFED during vs outside of the pollen season. Consecutive adult patients with EoE who underwent SFED and skin prick test (SPT) for birch and grass pollen were included. Individual pollen sensitization and pollen count data were analyzed to define whether each patient had been assessed during or outside of the pollen season after SFED. All patients had active EoE (≥15 eosinophils/high-power field) before SFED and adhered to the diet under the supervision of a dietitian.

RESULTS

Fifty-eight patients were included, 62.0% had positive SPT for birch and/or grass, whereas 37.9% had negative SPT. Overall, SFED response was 56.9% (95% confidence interval, 44.1%-68.8%). When stratifying response according to whether the assessment had been performed during or outside of the pollen season, patients sensitized to pollens showed significantly lower response to SFED during compared with outside of the pollen season (21.4% vs 77.3%; P = 0.003). In addition, during the pollen season, patients with pollen sensitization had significantly lower response to SFED compared with those without sensitization (21.4% vs 77.8%; P = 0.01).

DISCUSSION

Pollens may have a role in sustaining esophageal eosinophilia in sensitized adults with EoE despite avoidance of trigger foods. The SPT for pollens may identify patients less likely to respond to the diet during the pollen season.

Multiple staging investigations may not change management in patients with high-grade dysplasia or early esophageal adenocarcinoma

The clinical value of multiple staging investigations for high-grade dysplasia or early adenocarcinoma of the esophagus is unclear. A single-center prospective cohort of patients treated for early esophageal cancer between 2000 and 2019 was analyzed. This coincided with a transition period from esophagectomy to endoscopic mucosal resection (EMR) as the treatment of choice. Patients were staged with computed tomography (CT), endoscopic ultrasound (EUS) and 2-deoxy-2-[18F]fluoro-d-glucose (FDG) positron emission tomography(PET)/CT. The aim of this study was to assess their accuracy and impact on clinical management. 297 patients with high-grade dysplasia or early adenocarcinoma were included (endoscopic therapy/EMR n = 184; esophagectomy n = 113 [of which a 'combined' group had surgery preceded by endoscopic therapy n = 23]). Staging accuracy was low (accurate staging EMR: CT 40.1%, EUS 29.6%, FDG-PET/CT 11.0%; Esophagectomy: CT 43.3%, EUS 59.7%, FDG-PET/CT 29.6%; Combined: CT 28.6%, EUS46.2%, FDG-PET/CT 30.0%). Staging inaccuracies across all groups that could have changed management by missing T2 disease were CT 12%, EUS 12% and FDG-PET/CT 1.6%. The sensitivity of all techniques for detecting nodal disease was low (CT 12.5%, EUS 12.5%, FDG-PET/CT0.0%). Overall, FDG-PET/CT and EUS changed decision-making in only 3.2% of patients with an early cancer on CT and low-risk histology. The accuracy of staging with EUS, CT and FDG-PET/CT in patients with high-grade dysplasia or early adenocarcinoma of the esophagus is low. EUS and FDG-PET/CT added relevant staging information over standard CT in very few cases, and therefore, these investigations should be used selectively. Factors predicting the need for esophagectomy are predominantly obtained from EMR histology rather than staging investigations.

Single-centre, single-blinded, randomised, parallel group, feasibility study protocol investigating if mandibular advancement device treatment for obstructive sleep apnoea can reduce nocturnal gastro-oesophageal reflux (MAD-Reflux trial)

INTRODUCTION

Just under half of patients with obstructive sleep apnoea (OSA) also have gastro-oesophageal reflux disease (GORD). These conditions appear to be inter-related and continual positive airway pressure (CPAP) therapy, the gold standard treatment for OSA to prevent airway collapse, has been shown to reduce GORD. As the impact of mandibular advancement devices, a second-line therapy for OSA, on GORD has yet to be investigated, a feasibility study is needed prior to a definitive trial.

METHODS

This will be a single-centre, single-blinded, tertiary-care based, interdisciplinary, parallel randomised controlled study. Potential OSA participants presenting to the sleep department will be pre-screened for GORD using validated questionnaires, consented and invited to receive simultaneous home sleep and oesophageal pH monitoring. Those with confirmed OSA and GORD (n=44) will be randomly allocated to receive either CPAP (n=22) or MAD therapy (n=22). Following successful titration and 3 weeks customisation period, participants will repeat the simultaneous sleep and oesophageal pH monitoring while wearing the device. The number of patients screened for recruitment, drop-out rates, patient feedback of the study protocol, costs of interventions and clinical information to inform a definitive study design will be investigated.

ETHICS AND DISSEMINATION

Health Research Authority approval has been obtained from the Nottingham 2 Research Ethics Committee, ref:22/EM/0157 and the trial has been registered on ISRCTN (https://doi.org/10.1186/ISRCTN16013232). Definitive findings about the feasibility of doing 24 hour pH oesophageal monitoring while doing a home sleep study will be disseminated via clinical and research networks facilitating valuable insights into the simultaneous management of both conditions.

TRIAL REGISTRATION NUMBER

ISRCTN Reg No: 16013232.

How achievable are STRIDE-II treatment targets in real-world practice and do they predict long-term treatment outcomes?

Objective

The second iteration of the Selecting Therapeutic Targets in Inflammatory Bowel Disease (STRIDE-II) initiative recommends use of the Simple Endoscopic Score for Crohn's disease (SES-CD) as a treatment target for patients with CD. We aimed to assess whether the STRIDE-II endoscopic endpoints are achievable and whether the degree of mucosal healing (MH) affects long-term outcomes.

Design/method

We performed a retrospective observational study between 2015 and 2022. Patients with CD who had baseline and follow-up SES-CD scores after biological therapy initiation were included. The primary outcome was treatment failure, defined as the need for: (1) change of biological therapy for active disease (2) corticosteroid use (3) CD-related hospitalisation or (4) surgery. We compared rates of treatment failure with the degree of MH achieved. Patients were followed up until treatment failure or study end (August 2022).

Results

50 patients were included and followed up for median 39.9 (34.6-48.6) months. Baseline characteristics: 62% male, median age 36.4 (27.8-43.9) years, disease distribution (L1: 4, L2: 11, L3: 35, perianal: 18). The proportion of patients achieving STRIDE-II end-points were: SES-CD≤ 2-25 (50%) and >50% reduction in SES-CD-35 (70%). Failure to achieve SES-CD≤ 2 (HR 11.62; 95% CI 3.33 to 40.56, p=0.003) or >50% improvement in SES-CD (HR 30.30; 95% CI 6.93 to 132.40, p<0.0001) predicted treatment failure.

Conclusion

Use of SES-CD is feasible in real-world clinical practice. Achieving an SES-CD≤ 2 or a greater than 50% reduction, as set out by STRIDE-II, is associated with reduced rates of overall treatment failure including CD-related surgery.

A retrospective cohort study: pre-operative oral enteral nutritional optimisation for Crohn's disease in a UK tertiary IBD centre

BACKGROUND

Low-quality evidence suggests that pre-operative exclusive enteral nutrition (E/EN) can improve postoperative outcomes in patients with Crohn's disease (CD). It is not standard practice in most centres.

AIMS

To test the hypothesis that pre-operative EN in patients undergoing ileal/ileocolonic surgery for CD is associated with improved postoperative outcome.

METHODS

We performed a single centre retrospective observational study comparing surgical outcomes in patients receiving pre-operative EN (≥600 kcal/day for ≥2 weeks) with those who received no nutritional optimisation. Consecutive adult patients undergoing ileal/ileocolonic resection from 2008 to 2020 were included. The primary outcome was postoperative complications <30 days. Secondary outcomes included EN tolerance, specific surgical complications, unplanned stoma formation, length of stay, length of bowel resected, readmission and biochemical/anthropometric changes.

RESULTS

300 surgeries were included comprising 96 without nutritional optimisation and 204 optimised cases: oral EN n = 173, additional PN n = 31 (4 of whom had received nasogastric/nasojejunal EN). 142/204 (69.6%) tolerated EN. 125/204 (61.3%) initiated EN in clinic. Patients in the optimised cohort were younger at operation and diagnosis, with an increased frequency of penetrating disease and exposure to antibiotics or biologics, and were more likely to undergo laparoscopic surgery. The optimised cohort had favourable outcomes on multivariate analysis: all complications [OR 0.29; 0.15-0.57, p < 0.001], surgical complications [OR 0.41; 95% CI 0.20-0.87, p = 0.02], non-surgical complications [OR 0.24 95% CI 0.11-0.52, p < 0.001], infective complications [OR 0.32; 95% CI 0.16-0.66, p = 0.001].

CONCLUSIONS

Oral EN was reasonably well tolerated and associated with a reduction in 30-day postoperative complications. Randomised controlled trials are required to confirm these findings.

Positioning intestinal ultrasound in a UK tertiary centre: significant estimated clinical role and cost savings

OBJECTIVE

Intestinal ultrasound (IUS) is an inexpensive, non-invasive method of diagnosing and monitoring inflammatory bowel disease (IBD). We aimed to establish the proportion of lower gastrointestinal endoscopies (LGIEs) and magnetic resonance enterographies (MREs) that could have been performed as IUS, the potential pathology miss-rates if IUS was used and the associated cost savings.

METHODS

All MREs and LGIEs performed for either assessment of IBD activity or investigation of possible IBD, performed at a single UK tertiary centre in January 2018, were retrospectively reviewed against predetermined criteria for IUS suitability. Case outcomes were recorded and cost of investigation if IUS was performed instead was calculated.

RESULTS

73 of 260 LGIEs (28.1%) and 58 of 105 MREs (55.2%) met the criteria for IUS suitability. Among potential IUS-suitable endoscopy patients, one case each of a <5 mm adenoma and sessile serrated lesion were found; no other significant pathology that would be expected to be missed with IUS was encountered. Among IUS-suitable MRE patients, no cases of isolated upper gastrointestinal inflammation likely to be missed by IUS were found, and extraintestinal findings not expected to be seen on IUS were of limited clinical significance. The predicted cost saving over 1 month if IUS was used instead was £8642, £25 866 and £5437 for MRE, colonoscopy and flexible sigmoidoscopy patients, respectively.

CONCLUSION

There is a significant role for IUS, with annual projected cost savings of up to almost £500 000 at our centre. Non-inflammatory or non-gastrointestinal pathology predicted to be missed in this cohort was of limited clinical significance.

Transnasal endoscopy: moving from endoscopy to the clinical outpatient-blue sky thinking in oesophageal testing

BACKGROUND

COVID-19 has severely affected UK endoscopy services with an estimate 86% loss of activity during the first wave. Subsequent delays in diagnostic and surveillance procedures highlight the need for novel solutions to tackle the resultant backlog. Transnasal endoscopy (TNE) provides an attractive option compared with conventional upper gastrointestinal endoscopy given its limited use of space, no sedation and reduced nursing resources.

OUR EXPERIENCE

We describe piloting and then establishing an outpatient model TNE service in the pandemic era and the implications on resource allocation, training and workforce. We also discuss our experiences and outline ways in which services can evolve to undertake more complex endoscopic diagnostic and therapeutic work. Over 90% of patients describe no discomfort and those who have previously experienced conventional transoral endoscopy preferred the transnasal approach. We describe a low complication rate (0.8%) comprising two episodes of mild epistaxis. The average procedure duration was reasonable (9.9±5.0 min) with full adherence to Joint Advisory Group quality standards. All biopsies assessed were deemed sufficient for diagnosis including those for surveillance procedures.

DISCUSSION

TNE can offer a safe, tolerable, high-quality service outside of a conventional endoscopy setting. Expanding procedural capacity without impacting on the current endoscopy footprint has great potential in recovering endoscopy services following the COVID-19 pandemic. Looking forward, TNE has potential to be used both within the endoscopy suite as part of therapeutic procedures, or outside of the endoscopy unit in outpatient clinics, community hospitals, or mobile units and to achieve this in a more sustainable and environmentally friendly way.

Regular feedback to individual endoscopists is associated with improved adenoma detection rate and other key performance indicators for colonoscopy

OBJECTIVE

Monitoring of key performance indicators (KPIs) is a vital element of endoscopy quality improvement. Adenoma detection rate (ADR) is considered the best marker for colonoscopic quality as it inversely correlates with subsequent colonic cancer incidence and mortality, while polyp detection rate (PDR) is an easier-to-calculate surrogate for ADR. This study assessed whether regular feedback to individual endoscopists about their KPIs improved departmental performance.

METHODS

Individual KPIs were calculated for a period of 8 years (January 2012-December 2019) and fed back to all endoscopists at 6 monthly intervals, alongside anonymised indicators for other endoscopists, aggregate departmental performance data and benchmarks. An automated natural language processing software (EndoMineR) was used to identify adenomas in pathology reports and calculate ADR. Linear regressions were calculated for departmental ADR, PDR and other KPIs at 6 monthly intervals.

RESULTS

39 359 colonoscopies (average 2460 in every 6-month period, range 1799-3059) were performed by an average of 42 (range 34-50) endoscopists. A continuous improvement in collective performance including ADR (12.7%-21.0%, R² 0.92, p<0.001) and PDR (19.0%-29.6%, R² 0.77, p<0.001) was observed throughout the study. Other KPIs showed similar improvement. The detection of non-neoplastic polyps did not increase. When analysed separately, ADR and PDR appeared to improve for gastroenterologists and nurse endoscopists but not for surgeons.

CONCLUSION

Regular feedback with individual and departmental KPIs was associated with improved ADR and overall performance throughout the 8-year study period. Concomitant monitoring of ADR and PDR may prevent 'gaming' behaviour and ensure that genuine improvement is achieved.

P-OGC21 Patient perspectives on symptoms of importance and preferences for follow-up after major upper gastro-intestinal cancer surgery

Background

Long-lasting symptoms and reductions in quality of life are common after oesophago-gastric surgery. Post-operative follow-up has traditionally focussed on tumour recurrence and survival, but there is a growing need to also identify and treat functional sequelae to improve patients’ recovery.

Methods

An electronic survey was circulated via a British national charity for patients undergoing oesophago-gastric surgery and their families. Patients were asked about post-operative symptoms they deemed important to their quality of life, as well as satisfaction and preferences for post-operative follow-up.   Differences between satisfied and dissatisfied patients with reference to follow-up were assessed.

Results

Among 362 respondents with a median follow-up of 58 months since surgery (range 3-412), 36 different symptoms were reported as being important to recovery and quality of life after surgery, with a median 13 symptoms per patient. Most (84%) respondents indicated satisfaction with follow-up. Unsatisfied patients were more likely to have received shorter follow-up than 5 years  (27% among unsatisfied patient vs. 60% among satisfied patients, p &lt; 0.001and were less likely to have seen a dietitian as part of routine follow-up (37% vs. 58%, p = 0.005).

Conclusions

This patient survey highlights preferences with regard to follow-up after oesophago-gastrectomy. Longer follow-up and dietician involvement improved patient satisfaction. Patients reported being concerned by a large number of gastrointestinal and non-gastrointestinal symptoms, highlighting the need for multidisciplinary input and a consensus on how to manage the poly-symptomatic patient.  

Validation of the Lyon classification for GORD diagnosis: acid exposure time assessed by prolonged wireless pH monitoring in healthy controls and patients with erosive oesophagitis

OBJECTIVE

Acid exposure time (AET) from ambulatory pH studies and reflux oesophagitis are independent measurements used by the Lyon classification to diagnose GORD. This study aimed to validate AET reference ranges and diagnostic thresholds by analysis of 96-hour wireless pH studies from healthy, asymptomatic controls (HCs) and patients with and without oesophagitis.

DESIGN

HC and consecutive patients referred for wireless pH studies (off acid suppressants for >7 days) underwent 96-hour pH studies at two tertiary referral centres. Erosive oesophagitis was categorised by the Los Angeles (LA) classification. Linear regression and receiver operating curve (ROC) analysis were performed to define optimal diagnostic cut-offs.

RESULTS

Prolonged, 96-hour pH studies were completed in 39 HCs (age 28 (18-53) years, 72% female) and 944 patients (age 46 (16-85) years, 65% female), of whom 136 (14.5%) had reflux oesophagitis. Median AET in HC was 1.3% (upper 95th percentile 4.6%) for any study day and 2.6% (upper 95th percentile 6.9%) for the worst day (24-hour period) during the study. ROC analysis for average AET differentiated HC from patients with moderate-to-severe oesophagitis (LA BCD; sensitivity 87%, specificity 95%, positive predictive value (PPV) 59%, negative predictive value 99% for a cut-off AET of 4.3%; area under the receiver operating curve 0.95). Specificity was higher, but PPV was substantially lower for severe oesophagitis (LA CD). 'Worst-day' analysis provided similar results; however, day-to-day variability was high.

CONCLUSION

Diagnostic thresholds for average AET were identified that accurately discriminate between HCs and patients with erosive oesophagitis. The findings provide conditional support for diagnostic criteria for GORD proposed by the Lyon Consensus.

Occurrence of a human-associated microbial source tracking marker and its relationship with faecal indicator bacteria in an urban estuary

One of the main impacts of urban sprawl in rapidly growing countries has been contamination of coastal environments by waterborne pathogens, posing a critical risk to ecosystem and human health. Microbial source tracking (MST) has been a robust tool to identify the origin of these pathogens globally. This study compared the occurrence of a human-associated Bacteroides marker (BT-α) with faecal indicator bacteria (FIB) in an urban estuary (Golden Horn, Istanbul, Turkey). Faecal coliform (culture method), enterococci (both culture and qPCR method) concentrations and physicochemical variables were compared with the BT-α concentrations in monthly collected samples for a year (n = 108). Enterococci concentrations detected by culture and qPCR were positively correlated (r = 0·86, P < 0·01) suggesting that qPCR can be an alternative method for monitoring. BT-α marker was positive for 30% of the samples and positively correlated with enterococci (r = 0·61 and r = 0·64 for culture and qPCR methods respectively, P < 0·01). Rainfall had a moderate positive correlation with all faecal/MST indicators suggesting combined sewer overflows also severely impacted estuarine water quality. The high FIB and BT-α concentrations at upper estuary suggested that faecal pollution mainly originated from the peri-urban settlements around two creeks entering the estuary.

The effects of COVID-19 on IBD prescribing and service provision in a UK tertiary centre

BACKGROUND

To quantify the effects of COVID-19 on our inflammatory bowel disease (IBD) unit, including service provision, prescribing practices and use of therapeutic drug monitoring (TDM).

METHODS

We performed a single centre retrospective observational cohort study. Data was extracted from our IBD database, electronic patient records and radiology/endoscopy reporting systems between 16/3/20-17/4/20 and the corresponding period in 2019.

RESULTS

A similar number of patients commenced biologic therapy before COVID-19 (n = 37) and during the pandemic (n = 36). Patients in the pre-COVID-19 cohort were older (median 36 vs 29 years, P = 0.009) with a longer median disease duration (9.3 vs 5.2 years, P = 0.02). During COVID-19 there was a nonsignificant increase in prescribing of vedolizumab (8/37, 22% vs 14/36, 39%, P = 0.13) and a higher proportion of patients were anti-TNF-naïve (3/17, 18% vs 18/24, 74%, P = 0.0004). There was a reduction in use of concomitant immunomodulators (22/29, 76% vs 4/34, 12%, P < 0.0001) and increased biologic use in thiopurine-naïve patients (3/37, 8% vs 15/36, 42%, P = 0.001). Use of TDM fell by 75% (240 vs 59 tests). Outpatient appointments fell by 68% and were conducted via telemedicine. MRI scanning, endoscopy, luminal surgery and inpatient numbers fell by 87%, 85%, 100% and 82% respectively. IBD Clinical Nurse Specialist and Pharmacist helpline contacts increased by 76% and 228% respectively.

CONCLUSIONS

We observed prescribing differences during COVID-19, bypassing the initiation of immunomodulators and/or anti-TNF therapy in favour of vedolizumab with a reduction in immunomodulator prescribing. We also observed a rapid reorganisation of service provision, including a shift towards telemedicine and online solutions.

Prediction of a positive circumferential resection margin at surgery following neoadjuvant chemotherapy for adenocarcinoma of the oesophagus

Background

A positive circumferential resection margin (CRM) has been associated with higher rates of locoregional recurrence and worse survival in oesophageal cancer. The aim of this study was to establish if clinicopathological and radiological variables might predict CRM positivity in patients who received neoadjuvant chemotherapy before surgery for oesophageal adenocarcinoma.

Methods

Multivariable analysis of clinicopathological and CT imaging characteristics considered potentially predictive of CRM was performed at initial staging and following neoadjuvant chemotherapy. Prediction models were constructed. The area under the curve (AUC) with 95% confidence intervals (c.i.) from 1000 bootstrapping was assessed.

Results

A total of 223 patients were included in the study. Poor differentiation (odds ratio (OR) 2·84, 95 per cent c.i. 1·39 to 6·01) and advanced clinical tumour status (T3-4) (OR 2·93, 1·03 to 9·48) were independently associated with an increased CRM risk at diagnosis. CT-assessed lack of response (stable or progressive disease) following chemotherapy independently corresponded with an increased risk of CRM positivity (OR 3·38, 1·43 to 8·50). Additional CT evidence of local invasion and higher CT tumour volume (14 cm3) improved the performance of a prediction model, including all the above parameters, with an AUC (c-index) of 0·76 (0·67 to 0·83). Variables associated with significantly higher rates of locoregional recurrence were pN status (P = 0·020), lymphovascular invasion (P = 0·007) and poor response to chemotherapy (Mandard score 4-5) (P = 0·006). CRM positivity was associated with a higher locoregional recurrence rate, but this was not statistically significant (P = 0·092).

Conclusion

The presence of advanced cT status, poor tumour differentiation, and CT-assessed lack of response to chemotherapy, higher tumour volume and local invasion can be used to identify patients at risk of a positive CRM following neoadjuvant chemotherapy.

A biomarker panel predicts progression of Barrett's esophagus to esophageal adenocarcinoma

Progression from Barrett's esophagus (BE) to esophageal adenocarcinoma (EAC) is uncommon but the consequences are serious. Predictors of progression are essential to optimize resource utilization. This study assessed the utility of a promising panel of biomarkers applicable to routine paraffin embedded biopsies (FFPE) to predict progression of BE to EAC in a large population-based, nested case-control study.We utilized the Amsterdam-based ReBus nested case-control cohort. BE patients who progressed to high-grade dysplasia (HGD)/EAC (n = 130) and BE patients who never progressed (n = 130) were matched on age, sex, length of the BE segment, and duration of endoscopic surveillance. All progressors had minimum 2 years of endoscopic surveillance without HGD/EAC to exclude prevalent neoplasia. We assessed abnormal DNA content, p53, Cyclin A, and Aspergillus oryzae lectin (AOL) in FFPE sections. We performed conditional logistic regression analysis to estimate odds ratio (OR) of progression based on biomarker status.Expert LGD (OR, 8.3; 95% CI, 1.7-41.0), AOL (3 vs. 0 epithelial compartments abnormal; OR, 3.6; 95% CI, 1.2-10.6) and p53 (OR, 2.3; 95% CI, 1.2-4.6) were independently associated with neoplastic progression. Cyclin A did not predict progression and DNA ploidy analysis by image cytometry was unsuccessful in the majority of cases, both were excluded from the multivariate analysis. The multivariable biomarker model had an area under the receiver operating characteristic curve of 0.73.Expert LGD, AOL, and p53 independently predict neoplastic progression in BE patients and are applicable to routine practice. These biomarkers can aid in selecting patients for endoscopic ablation or more intensive surveillance.

Uvular necrosis following diagnostic gastroscopy

Uvular necrosis is an extremely rare complication of gastroscopy. We describe the fifth published case of uvular necrosis following an uncomplicated diagnostic gastroscopy in a young man. Presentation with severe sore throat and inability to swallow saliva occurred within 24 hours of gastroscopy and resolved with conservative treatment.

■ REVIEW : Parallel Processing, Asynchronous Perception, and a Distributed System of Consciousness in Vision

The primate visual brain is characterized by a set of parallel, multistage systems that are specialized to process different attributes of the visual scene. They occupy spatially distinct positions in the visual brain and do not project to a unique common area. These processing systems are also perceptual systems, because the result of activity in each leads to the perception of the relevant visual attribute. But the different processing-perceptual systems require different times to complete their tasks, thus leading to another char acteristic of the visual brain, a temporal hierarchy for perception. Together, these two characteristics—of parallel processing and temporal hierarchy—suggest that each processing-perceptual system can act with fair autonomy. Studies of the diseased human brain show that activity in separate processing-perceptual systems—especially those concerned with color and motion—can lead to the perception of the relevant attribute even when the other processing systems are inactive and that activity in individual processing- perceptual systems has a conscious experience as a correlate, which suggests that consciousness itself is a modular, distributed system. NEUROSCIENTIST 4:365-372, 1998

The Conscious Vision of the Blind

The most fundamental function of the visual brain is to acquire knowledge about the constant, essential properties of the visual world, in conditions in which the information reaching the brain is never constant from moment to moment. This requires the brain to undertake complex operations on the incoming visual signals, discounting all that is not essential for it to acquire knowledge about the world, selecting that which is important, and subjecting the latter to operations that make the brain independent of the continually changing and non-essential information reaching it. One strategy that the brain uses in undertaking this task is that of functional specialisation, through which different essential features, such as motion and colour, are extracted in specialised and geographically distinct visual areas lying outside the primary visual cortex area V1. Our recent psychophysical experiments show that, just as the processing systems for different attributes of vision are separate, so are the final perceptual systems, since different attributes of the visual scene such as colour, form, and motion are perceived at different times, with colour being ahead of motion by about 80 ms, thus leading to a perceptual asynchrony in terms of real time. The end-result of the operations in these individual areas is the acquisition of knowledge. But knowledge can only be acquired in the conscious state. A conscious awareness is therefore the corollary of activity in the specialised areas. Recent experiments using imaging and time resolution methods as well as patients blinded by lesions either in V1 or in more extensive parts of the visual cortex show that the activity in one or a small number of visual areas, without involvement of V1, can give rise to both conscious experience and a crude knowledge about the visual world. This leads us to the conclusion that consciousness itself may be modular.

Genomics of Esophageal Cancer and Biomarkers for Early Detection

In-depth molecular characterization of esophageal oncogenesis has improved over the recent years. Advancement in molecular biology and bioinformatics has led to better understanding of its genomic landscape. More specifically, analysis of its pathogenesis at the genetic level has uncovered the involvement of a number of tumor suppressor genes, cell cycle regulators, and receptor tyrosine kinases. Due to its poor prognosis, the development of clinically applicable biomarkers for diagnosis, progression, and treatment has been the focus of many research studies concentrating on upper gastrointestinal malignancies. As in other cancers, early detection and subsequent intervention of the preneoplastic condition significantly improves patient outcomes. Currently, clinically approved surveillance practices heavily depend on expensive, invasive, and sampling-error-prone endoscopic procedures. There is, therefore, a great demand to establish clearly reliable biomarkers that could identify those patients at higher risk of neoplastic progression and hence would greatly benefit from further monitoring and/or intervention. This chapter will present the most recent advances in the analysis of the esophageal cancer genome serving as basis for biomarker development.

Targeting care in Barrett's oesophagus

Barretts oesophagus represents the most significant risk factor for the development of oesophageal adenocarcinoma (OAC), although the majority of patients will not develop cancer. However, early detection of OAC and its precursors significantly improves outcome and underlines the importance of endoscopic surveillance programmes. Clearly there is a discrepancy between the small number of people who need to undergo surveillance because they are at significant progression risk, and the large number that do. Research is therefore now concentrated on risk stratification. Currently such stratification is currently based on clinical findings, endoscopic diagnosis and histopathological grade. Histopathology can be imperfect and is likely to require molecular confirmation of different grades, thus molecular stratification is becoming more important in this regard and p53 immunohistochemistry is already clinically useful, with other molecular biomarkers likely to prove beneficial in the future. The hope is that non-endoscopic methods, such as the Cytosponge may be able to combine molecular biomarkers with histopathology and therefore perhaps benefit a population screening as well as a surveillance programme.

Crypt dysplasia in Barrett's oesophagus shows clonal identity between crypt and surface cells

Epithelial dysplasia is an important histological diagnosis signifying the presence of pre-invasive disease, usually needing intervention. However, the specific genetic changes responsible for the induction of this phenotypic change are unknown. Moreover, recent reports indicate that the dysplastic phenotype may not be immutable: in basal crypt dysplasia (CD), unequivocal dysplastic changes are seen in the crypts in Barrett's oesophagus and other pre-invasive lesions in the gastrointestinal tract, but the upper crypts and surface epithelium associated with these dysplastic crypts show the definitive morphology of a differentiated epithelium. The genotypic relationship between CD and the differentiated surface epithelium is presently unclear. We obtained 17 examples of CD: the lower and upper crypts and surface epithelium were differentially laser-microdissected from formalin-fixed, paraffin-embedded sections and mutations were sought in tumour suppressor genes frequently associated with progression in Barrett's oesophagus. We found two patients who both showed a c. C238T mutation in the CDKN2A (CDKN2AInk4A) gene and where the precise microanatomical relationships could be discerned: this mutation was present in both the CD at the crypt base and in the upper crypt and surface epithelium. We conclude that, in CD, the dysplastic basal crypt epithelium and the upper crypt and surface epithelium show clonal CDKN2A mutations, thus showing definitively that the surface epithelium is derived from the dysplastic crypt epithelium: the dysplastic phenotype is therefore not fixed and can be reversed. The mechanism of this change is unclear but may be related to the possibility that dysplastic cells can, probably early in their progression, respond to differentiation signals. However, it is also clear that a heavy mutational burden can be borne by crypts in the gastrointestinal tract without the development of phenotypic dysplasia. We are evidently some way from understanding the plasticity and the genotypic correlates of the dysplastic phenotype.

The brain's specialized systems for aesthetic and perceptual judgment

We recorded brain activity when 21 subjects judged the beauty (aesthetic or affective judgment) and brightness (perceptual or cognitive judgment) of simultaneously presented paintings. Aesthetic judgments engaged medial and lateral subdivisions of the orbitofrontal cortex as well as subcortical stations associated with affective motor planning (globus pallidus, putamen-claustrum, amygdala, and cerebellar vermis), whereas the motor, premotor and supplementary motor areas, as well as the anterior insula and the dorsolateral prefrontal cortex, were engaged by both kinds of judgment. The results lead us to conclude: (i) that there is a functional specialization for judgment, with aesthetic judgments engaging distinct systems, in addition to those that they share with perceptual judgments; (ii) that the systems engaged by affective judgments are those in which activity correlates with polar experiences (e.g. love-hate, beauty-ugliness, and attraction-repulsion); and (iii) that there is also a functional specialization in the motor pathways, with aesthetic judgments engaging motor systems not engaged by perceptual judgments, in addition to those engaged by both kinds of judgment.

Utilizing DNA mutations to trace epithelial cell lineages in human tissues

Epithelial stem cells are typically multipotential and are likely the cell of origin of epithelial cancers. Tracing the expansion of a single stem cell's progeny, identifying and characterizing these cells in human tissue has proven difficult. Invasive labeling studies, which have led to much success in model organisms, are impracticable in humans. Instead, human studies must rely upon naturally occurring clonal markers: typically somatic DNA alterations that uniquely identify a population of cells with the same ancestry. In normal epithelium, nonpathogenic mitochondrial DNA mutations have proven useful. In premalignant and malignant disease, genomic DNA mutations within tumor suppressor genes or oncogenes can be used to trace the spread of mutant clones.

Risk factors for severe disease in adults with falciparum malaria

BACKGROUND

Over a 16-year period, we conducted a clinical study of malaria acquired worldwide in adults from malaria-nonendemic countries, to determine risk factors for severe Plasmodium falciparum malaria.

METHODS

All patients with confirmed malaria who were managed by our unit from 1991 to 2006 were prospectively evaluated. Factors predicting disease severity according to (1) strict World Health Organization (WHO) criteria, (2) a composite measure of unfavorable outcome, and (3) length of hospital stay were identified by logistic and linear regression analyses.

RESULTS

We evaluated 676 episodes of malaria, 482 (71%) due to P. falciparum and 194 (29%) due to nonfalciparum parasites. Black patients had a significantly reduced risk of developing WHO-defined severe falciparum malaria, with Asian patients having odds of severe falciparum malaria that were 8.05-fold (95% confidence interval [CI], 2.93-22.1-fold) higher and white patients having odds that were 8.20-fold (95% CI, 2.94-22.9-fold) higher. Black patients also had a reduced risk of an unfavorable outcome and of a prolonged stay in the hospital, compared with the risks for white or Asian patients. Of 6 patients with falciparum malaria who died, none were black. In univariate analysis, patients with parasitemias of >or= 2% had odds of severe falciparum malaria 12-fold higher than those of patients with parasitemias of <2% (73% vs. 19%). Patients with a history of previous clinical malaria, regardless of ethnicity, had a significantly reduced risk of WHO-defined severe falciparum malaria (odds ratio, 0.35 [95% CI, 0.15-0.80]).

CONCLUSIONS

The findings of this study demonstrate that ethnicity and parasitemia are important independent risk factors for severe falciparum malaria in adults from malaria-nonendemic countries and that a history of previous clinical malaria significantly reduces the risk of WHO-defined severe falciparum malaria.

An obstructing mass in a young ulcerative colitis patient

We present a case of a 19-year-old female who developed subacute obstruction due to giant inflammatory polyps, having undergone treatment for left-sided ulcerative colitis. This is followed by a review of the literature.

A thought experiment with positron emission tomography

This paper describes a thought experiment. The experiment supposes that the technique of positron emission tomography (PET), as we known it today, was available in 1920 and had been applied then to a study of the visual cortex of man. The 'results' of the experiment show that such an approach would have generated new concepts about the functioning of the visual cortex, and that PET can therefore be considered to be an hypothesis-generating technique.

Natural vision reveals regional specialization to local motion and to contrast-invariant, global flow in the human brain

Visual changes in feature movies, like in real-live, can be partitioned into global flow due to self/camera motion, local/differential flow due to object motion, and residuals, for example, due to illumination changes. We correlated these measures with brain responses of human volunteers viewing movies in an fMRI scanner. Early visual areas responded only to residual changes, thus lacking responses to equally large motion-induced changes, consistent with predictive coding. Motion activated V5+ (MT+), V3A, medial posterior parietal cortex (mPPC) and, weakly, lateral occipital cortex (LOC). V5+ responded to local/differential motion and depended on visual contrast, whereas mPPC responded to global flow spanning the whole visual field and was contrast independent. mPPC thus codes for flow compatible with unbiased heading estimation in natural scenes and for the comparison of visual flow with nonretinal, multimodal motion cues in it or downstream. mPPC was functionally connected to anterior portions of V5+, whereas laterally neighboring putative homologue of lateral intraparietal area (LIP) connected with frontal eye fields. Our results demonstrate a progression of selectivity from local and contrast-dependent motion processing in V5+ toward global and contrast-independent motion processing in mPPC. The function, connectivity, and anatomical neighborhood of mPPC imply several parallels to monkey ventral intraparietal area (VIP).

The neurobiology of love

Romantic and maternal love are highly rewarding experiences. Both are linked to the perpetuation of the species and therefore have a closely linked biological function of crucial evolutionary importance. The newly developed ability to study the neural correlates of subjective mental states with brain imaging techniques has allowed neurobiologists to learn something about the neural bases of both romantic and maternal love. Both types of attachment activate regions specific to each, as well as overlapping regions in the brain's reward system that coincide with areas rich in oxytocin and vasopressin receptors. Both deactivate a common set of regions associated with negative emotions, social judgment and 'mentalizing' that is, the assessment of other people's intentions and emotions. Human attachment seems therefore to employ a push-pull mechanism that overcomes social distance by deactivating networks used for critical social assessment and negative emotions, while it bonds individuals through the involvement of the reward circuitry, explaining the power of love to motivate and exhilarate. Yet the biological study of love, and especially romantic love, must go beyond and look for biological insights that can be derived from studying the world literature of love, and thus bring the output of the humanities into its orbit.

The Sightless View: Neural Correlates of Occluded Objects

The relationship between neural activity and object perception has received considerable attention using stimulus manipulations such as masking or dichoptic presentation. Here we investigate the same problem by occluding objects with an opaque screen that acts to dissociate the direct perception of the object from the awareness of its presence. We used functional magnetic resonance imaging to measure brain activity when subjects viewed objects (faces and houses) that underwent occlusion and found that the response of the majority of the fusiform face area (FFA) and lateral occipital cortex is the same whether the object is visible or occluded. This suggests that when objects are directly viewed, activity within object-selective regions may reflect the awareness of presence, not the direct perception, of the object. Additionally, we identify a region of premotor cortex that is selectively activated by occlusion of either object type, suggesting its generic involvement with processing occluded objects.

The temporal order of binding visual attributes

The brain processes distinct attributes such as colour and motion in anatomically largely segregated systems. Moreover, these two attributes are perceived with different latencies. Here, we show that the time required to bind these two attributes differs too. In psychophysical experiments, we determined minimal presentation times required to perceptually pair spatially separate pairs of stimuli consisting of colour or motion. Binding two colours required longer presentation times than binding the directions of two moving stimuli. Cross-attribute binding between colour and motion took longer than within-attribute binding. This was so even when the relative perceptual delay between colour and motion was compensated for, which accelerated colour-motion binding. Moreover, stimuli could be discriminated but not bound at fast presentation rates. Our results thus show that spatial binding is an attribute-specific process and faster within the same than across different attributes. Furthermore, the time required to bind attributes is independent of that required to process them, since colour is perceived before motion but requires longer time for binding. Finally, our results suggest that binding acts on attribute-specific neural representations of the stimuli at a late, perceptually explicit stage. These results lead us to conclude that spatial binding is separate from, and subsequent to, stimulus processing and that it is an attribute-dependent and post-conscious process.

The Integration of Colour and Motion by the Human Visual Brain

Objects in the visual scene are defined by different cues such as colour and motion. Through the integration of these cues the visual system is able to utilize different sources of information, thus enhancing its ability to discriminate objects from their backgrounds. In the following experiments, we investigate the neural mechanisms of cue integration in the human. We show, using functional magnetic resonance imaging (fMRI), that both colour and motion defined shapes activate the lateral occipital complex (LOC) and that shapes defined by both colour and motion simultaneously activate the anterior-ventral margins of this area more strongly than shapes defined by either cue alone. This suggests that colour and motion cues are integrated in the LOC and possibly a neighbouring, more anterior, region. We support this result using an fMR adaptation technique, demonstrating that a region of the LOC adapts on repeated presentations of a shape regardless of the cue that is used to define it and even if the cue is varied. This result raises the possibility that the LOC contains cue-invariant neurons that respond to shapes regardless of the cue that is used to define them. We propose that such neurons could integrate signals from different cues, making them more responsive to objects defined by more than one cue, thus increasing the ability of the observer to recognize them.

Preface

The legal process is often invoked to resolve scientific or economic problems such as may arise when a bridge collapses, or an aeroplane crashes, or a ship sinks; or when a mishap occurs on the operating table; or when patent protection is sought for an invention claimed to be novel; or when it is necessary to assess the effect of a commercial practice on competition in a market; or when a baby dies, for no apparent reason, in its cot; or when it is sought to identify a fingerprint on a murder weapon.

The disunity of consciousness

Attempts to decode what has become known as the (singular) neural correlate of consciousness (NCC) suppose that consciousness is a single unified entity, a belief that finds expression in the term 'unity of consciousness'. Here, I propose that the quest for the NCC will remain elusive until we acknowledge that consciousness is not a unity, and that there are instead many consciousnesses that are distributed in time and space.

The processing of kinetic contours in the brain

This work investigates whether the brain assigns special cortical areas for the processing of kinetic contours. In human imaging experiments, we compared the brain activity produced in the so-called 'kinetic occipital' area ('KO') when humans perceive shapes generated from kinetic boundaries or from equiluminant colors. 'KO' was activated whenever subjects perceived shapes, no matter how they were derived; it is therefore not specialized for the processing of kinetic contours. The application of independent component analysis (ICA) to imaging data obtained when subjects viewed 22 min of an action movie showed that the time course of activity in 'KO' correlates better with activity in area V3 than with activity in two adjacent areas, V5 and LO. We thus consider 'KO' to be part of the V3 family of areas, and use the terminology of Smith et al. (J Neurosci 18:3816-3830, 1998), to refer to it as area V3B. Recordings from orientation-selective cells in the macaque V3 complex show that the great majority have the same orientational specificity when tested with oriented lines generated from kinetic stimuli or from luminance differences. We conclude that there is no present evidence for a visual area specialized for the processing of kinetic contours in the primate visual brain.

The Organization of Connections between Areas V5 and V2 in Macaque Monkey Visual Cortex

Area V2 of the cerebral cortex of higher primates has a complex cytochrome oxidase architecture whose most characteristic element is a set of stripes running orthogonal to its long axis. These stripes can be related to the segregation between the various pathways in which V2 participates. In the macaque monkey the more metabolically active stripes are alternately thick and thin and only one set, the thick stripes, is found to possess clusters of labelled cells following injections of horseradish peroxidase - wheatgerm agglutinin into area V5. Some of these clusters, but not all, coincide with substructures inside the thick stripes. V2 of the owl monkey has a similar organization except that the diversification into thick and thin stripes is less prominent, both in terms of their appearance and in that more than every alternate stripe is connected to area MT, the likely homologue of V5. The return projection from V5 to V2 is more widespread than the origin of the forward projection. It extends not only between the clusters of V5-efferent cells within the thick stripes but also across the intervening thin stripes and less active interstripes. Because the latter subserve functions different from those of the thick stripes it would seem that their receipt of a back projection from an area to which they do not project, V5, may be relevant to the process of intergration of signals relating to different attributes of vision.

Modular Connections between Areas V2 and V4 of Macaque Monkey Visual Cortex

We have studied the connections between two visual areas of macaque monkey cortex, V2 and V4, by injecting wheat-germ agglutinin horseradish peroxidase (HRP-WGA) into V4 and examining the distribution of labelled cells and terminals in V2, in relation to its characteristically striped cytochrome oxidase architecture. The cells projecting from V2 to V4 are arranged in bands and the number of bands per cycle of cytochrome oxidase stripes varies (one cycle consists of a thin stripe, a thick stripe and two interstripes). In the Type 1 connectivity pattern, there is just one band per cycle, centred over the thin stripes but normally spreading into the neighbouring interstripes. In the Type 2 connectivity pattern there are two bands per cycle, generally rather narrower and centred over the interstripes. Thick stripes are mostly free of labelled cells. The return projection from V4 to V2, whilst being concentrated in the vicinity of the labelled cells, is more diffusely distributed and invades the territory of all the stripes.

The Organization of Connections between Areas V5 and V1 in Macaque Monkey Visual Cortex

Area V5 or MT of primate extrastriate visual cortex is specialized for involvement in the analysis of motion and receives input from two layers, 4B and 6, of the striate cortex or V1. Injections of horseradish peroxidase - wheatgerm agglutinin into V5 reveal a patchy distribution of labelled cells and axonal terminals in layer 4B, suggesting the presence of a segregated and functionally specialized subsystem within the layer. The patches are similar in size and frequency to the cytochrome oxidase blobs of layers 2 and 3, but bear little systematic relationship to them. V5-efferent cells in layer 6, however, tend to avoid the cores of the blobs. The back projection from V5 is continuously distributed in layers 6 and 1, though it is absent inside representations of the central 10 degrees in the latter; it is also diffusely distributed between the patches in layer 4B and over a territory wider than that occupied by labelled cells. It is thus inferred that the back projection probably influences (a) V5-efferent cells other than those projecting to the injected site in V5, and (b) cells projecting to locations other than V5. There are no major changes in the cortical frequency of V5-efferent cells with eccentricity in the visual field representation. The V5-efferent cells of layer 6 are tenfold less frequent than those of layer 4B and as a population may therefore be involved with only a limited sector of directions of movement. Furthermore, their topographic distribution does not always coincide exactly with that of the layer 4B population, as if a site in V5 receives information about slightly non-corresponding regions of the visual field from the two layers.

The relationship between cortical activation and perception investigated with invisible stimuli

The aim of this work was to study the relationship between cortical activity and visual perception. To do so, we developed a psychophysical technique that is able to dissociate the visual percept from the visual stimulus and thus distinguish brain activity reflecting the perceptual state from that reflecting other stages of stimulus processing. We used dichoptic color fusion to make identical monocular stimuli of opposite color contrast "disappear" at the binocular level and thus become "invisible" as far as conscious visual perception is concerned. By imaging brain activity in subjects during a discrimination task between face and house stimuli presented in this way, we found that house-specific and face-specific brain areas are always activated in a stimulus-specific way regardless of whether the stimuli are perceived. Absolute levels of cortical activation, however, were lower with invisible stimulation compared with visible stimulation. We conclude that there is no terminal "perceptual" area in the visual brain, but that the brain regions involved in processing a visual stimulus are also involved in its perception, the difference between the two being dictated by a higher level of activity in the specific brain region when the stimulus is perceived.

Responses of spectrally selective cells in macaque area V2 to wavelengths and colors

We have recorded from wavelength-selective cells in macaque monkey visual area V2, interposed between areas V1 and V4 of the color-specialized pathway, to learn whether their responses correlate with perceived colors or are determined by the wavelength composition of light reflected from their receptive fields. All the cells we recorded from were unselective for the orientation and direction of motion of the stimulus, and all were histologically identified to be in the thin cytochrome oxidase stripes. Using multi-colored "Mondrian" scenes of the appropriate spatial configuration, areas of different color were placed in the receptive field of each cell and the entire scene illuminated by three projectors, passing long-, middle-, and short-wave light, respectively, in various combinations. Our results show that wavelength-selective cells in V2 respond to an area of any color depending on whether or not it reflects a sufficient amount of light of their preferred wavelength. In addition, the responses of a third of the cells tested were also influenced by the wavelength composition of their immediate surrounds, thus signaling the result of a local spatial comparison with respect to the amount of their preferred wavelength present. The responses of all also depended on the sequence with which their receptive fields were illuminated with light of the three different wavebands: cells were activated when there was an increase (and inhibited when there was a decrease) in the amount of their preferred wavelength with respect to the other two; the temporal route taken was therefore a determining factor, and, depending on it, cells would either respond or not to a particular combination of wavelengths. We conclude that although spatiotemporal wavelength comparisons are taking place in the color-specialized subdivisions of area V2, the determination of complete color-constant behavior at the neuronal level requires further processing, in other areas.

Functional organization of macaque V3 for stereoscopic depth

Recordings were made from single and small groups of cells in prestriate area V3 of the visual cortex of the Cynomolgus macaque (Macaca fascicularis). The majority of cells in V3 were selective for orientation and stereoscopic depth, these cells being segregated into two sets of functionally distinct columns. Orientation columns in V3 have been previously demonstrated; here we show that V3 also contains columns of segregated disparity-selective cells. On the basis of its cellular properties, functional organization, and intra-cortical connections, we propose that V3 contributes to the processing of stereoscopic depth information and that the parietal areas to which it projects use this information for the analysis of object depth and three-dimensional form.

Localization and globalization in conscious vision

The primate visual brain consists of many separate, functionally specialized processing systems, each consisting of several apparently hierarchical stages or nodes. The evidence reviewed here leads me to speculate (a) that the processing systems are autonomous with respect to one another, (b) that activity at each node reaches a perceptual end point at a different time, resulting in a perceptual asynchrony in vision, and (c) that, consequently, activity at each node generates a microconsciousness. Visual consciousness is therefore distributed in space and time, with the universal organizing principle of abstraction applied separately within each processing system. The consequence of spatially and temporally distributed microconsciousnesses is that their integration is a multistage, nonhierarchical process that may involve a neural "glue."

Hepatocellular oxidative DNA injury induced by macrophage-derived nitric oxide

Previous studies have indicated that splenic macrophages migrate into the liver and play a role in endotoxin-induced hepatic damage. The present study was designed to elucidate the mechanisms of hepatocyte injury induced by activated splenic macrophages, focusing especially on endogenously released NO and oxidative DNA alterations in hepatocytes. Splenic macrophages isolated from Wistar rats were incubated with either lipopolysaccharide (LPS) or interferon-gamma (IFN-gamma) and cocultured with hepatocytes. Nitrite and nitrate levels in the culture medium were measured, and inducible-type NO synthase (iNOS) and nitrotyrosine were determined by immunofluorescence staining. The ratio of 8-hydroxy-deoxyguanosine (8-OH-dG) to deoxyguanosine (dG) was measured by high-performance liquid chromatography, and single-stranded DNA in hepatocytes was detected with acridine orange. NO release and nitrotyrosine expression in hepatocytes increased after 8 h of coculture with activated macrophages, and this coculture also induced increases in the 8-OH-dG/dG ratio and single-stranded DNA in the hepatocytes. These alterations were attenuated by superoxide dismutase (SOD) and NO synthesis inhibitors. A similar pattern of alterations was observed in hepatocytes incubated with SIN-1, and these changes were also prevented by SOD. These results suggest that activated macrophage-derived NO and its oxidative metabolite, peroxynitrite, play key roles in hepatocyte injury during inflammation, and cause subsequent DNA damage in surviving hepatocytes.

The neural basis of romantic love

The neural correlates of many emotional states have been studied, most recently through the technique of fMRI. However, nothing is known about the neural substrates involved in evoking one of the most overwhelming of all affective states, that of romantic love, about which we report here. The activity in the brains of 17 subjects who were deeply in love was scanned using fMRI, while they viewed pictures of their partners, and compared with the activity produced by viewing pictures of three friends of similar age, sex and duration of friendship as their partners. The activity was restricted to foci in the medial insula and the anterior cingulate cortex and, subcortically, in the caudate nucleus and the putamen, all bilaterally. Deactivations were observed in the posterior cingulate gyrus and in the amygdala and were right-lateralized in the prefrontal, parietal and middle temporal cortices. The combination of these sites differs from those in previous studies of emotion, suggesting that a unique network of areas is responsible for evoking this affective state. This leads us to postulate that the principle of functional specialization in the cortex applies to affective states as well.