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Background and study aims Reprocessing reusable endoscopes is challenging due to their non-sterilizable nature. Disinfection has been shown to have a significant risk of failure with serious consequences. Single-use endoscopes can eliminate contamination risk and reduce workflow delays caused by reprocessing. This study evaluated the clinical performance of single-use gastroscopes in patients undergoing esophagogastroduodenoscopy (EGD). Patients and methods In this case series, 60 patients underwent EGD using single-use gastroscopes, with 34 procedures in the endoscopy department and 26 in the intensive care unit. The primary outcome was successful completion of the intended EGD objective. Furthermore, certified endoscopists assessed device performance on a five-point Likert scale (ranging from 1-"much worse" to 5-"much better"), considering their experience with a reusable gastroscope. Results Successful completion of EGDs using only the single-use gastroscope was achieved in 58 of 60 cases (96.7%). In two cases, crossover to an ultra-slim endoscope was necessary to either reach the esophageal stenosis or to transverse the stenosis. Overall satisfaction was rated as comparable to reusable scopes in 51 of 56 cases (91.1%) and inferior in five cases (8.9%). The lower weight of the single-use gastroscope was rated as superior in 42 of 60 cases (70.0%). Drawbacks included reduced image quality (23 of 45 cases; 51.1%). Feedback included the absence of a freeze button, lens cleaning issues, and small image size. Conclusions Single-use gastroscopes exhibited a high EGD completion rate and effectiveness for various indications. Further research should focus on evaluating the implementation of single-use gastroscopes in a comprehensive context, considering clinical effectiveness, costs, and environmental impact., Competing Interests: Conflict of Interest KvdP, ADK, WJL and VP declare no conflict of interests for this article. PJFJ acted as consultant/lecturer for Boston Scientific. MCV has received research support from Boston Scientific, 3M and Pentax Medical. LA is a member of the advisory board of AMBU. MJB has received research support from Boston Scientific, Cook Medical, Pentax Medical, Mylan, ChiRoStim and acted as a consultant/lecturer for Boston Scientific, Cook Medical, Pentax Medical and AMBU., (The Author(s). This is an open access article published by Thieme under the terms of the Creative Commons Attribution License, permitting unrestricted use, distribution, and reproduction so long as the original work is properly cited. (https://creativecommons.org/licenses/by/4.0/).)

Background & Aims: The Primary Biliary Cholangitis (PBC) Obeticholic Acid (OCA) International Study of Efficacy (POISE) randomized, double-blind, placebo-controlled trial demonstrated that OCA reduced biomarkers associated with adverse clinical outcomes (ie, alkaline phosphatase, bilirubin, aspartate aminotransferase, and alanine aminotransferase) in patients with PBC. The objective of this study was to evaluate time to first occurrence of liver transplantation or death in patients with OCA in the POISE trial and open-label extension vs comparable non-OCA-treated external controls., Methods: Propensity scores were generated for external control patients meeting POISE eligibility criteria from 2 registry studies (Global PBC and UK-PBC) using an index date selected randomly between the first and last date (inclusive) on which eligibility criteria were met. Cox proportional hazards models weighted by inverse probability of treatment assessed time to death or liver transplantation. Additional analyses (Global PBC only) added hepatic decompensation to the composite end point and assessed efficacy in patients with or without cirrhosis., Results: During the 6-year follow-up, there were 5 deaths or liver transplantations in 209 subjects in the POISE cohort (2.4%), 135 of 1381 patients in the Global PBC control (10.0%), and 281 of 2135 patients in the UK-PBC control (13.2%). The hazard ratios (HRs) for the primary outcome were 0.29 (95% CI, 0.10-0.83) for POISE vs Global PBC and 0.30 (95% CI, 0.12-0.75) for POISE vs UK-PBC. In the Global PBC study, HR was 0.20 (95% CI, 0.03-1.22) for patients with cirrhosis and 0.31 (95% CI, 0.09-1.04) for those without cirrhosis; HR was 0.42 (95% CI, 0.21-0.85) including hepatic decompensation., Conclusions: Patients treated with OCA in a trial setting had significantly greater transplant-free survival than comparable external control patients., (Copyright © 2022 The Authors. Published by Elsevier Inc. All rights reserved.)

Background: After 1 year of ursodeoxycholic acid (UDCA), patients with primary biliary cholangitis (PBC) may have a normal GLOBE score despite high alkaline phosphatase (ALP) levels., Aim: To assess the association between ALP and liver transplantation (LT)-free survival according to the GLOBE score METHODS: Among patients with a normal or elevated GLOBE score in the Global PBC cohort, the association between ALP after 1 year of UDCA and the risk of LT/death was assessed. The LT-free survival was compared with that of a matched general population., Results: After 1 year of UDCA, ALP was associated with the risk of LT/death (aHR 1.31, 95% CI 1.003-1.72, p = 0.048) among 2729 patients with a normal GLOBE score. The 10-year LT-free survival among these patients with an ALP >2.0 × ULN was 94.0% (95% CI 90.1-97.9) for those <50 years, and 82.6% (95% CI 76.5-88.7) for those ≥50 years, which was significantly lower (p = 0.040) and similar (p = 0.736) to that of the matched population, respectively. The 10-year LT-free survival in patients ≥50 years with normal GLOBE score and normal ALP (90.8%, 95% CI 87.7-93.9) was significantly higher (p = 0.022) than the matched population. Among 1045 patients with an elevated GLOBE score, ALP was associated with LT/death only in those <50 years (aHR 1.38, 95% CI 1.06-1.81, p = 0.016)., Conclusion: The LT-free survival of patients with PBC with a normal GLOBE score is optimal in case of normal ALP levels, also in relation to the general population. Despite their generally favourable prognosis, an elevated ALP level may still indicate a need for add-on therapy., (© 2022 The Authors. Alimentary Pharmacology & Therapeutics published by John Wiley & Sons Ltd.)

Background & Aims: Gamma-glutamyltransferase (GGT) is a serum marker of cholestasis. We investigated whether serum level of GGT is a prognostic marker for patients with primary biliary cholangitis (PBC)., Methods: We analyzed data from patients with PBC from the Global PBC Study Group, comprising 14 centers in Europe and North America. We obtained measurements of serum GGT at baseline and time points after treatment. We used Cox model hazard ratios to evaluate the association between GGT and clinical outcomes, including liver transplantation and liver-related death., Results: Of the 2129 patients included in our analysis, 281 (13%) had a liver-related clinical endpoint. Mean age at diagnosis was 53 years and 91% of patients were female patients. We found a correlation between serum levels of GGT and alkaline phosphatase (ALP) (r = 0.71). Based on data collected at baseline and yearly for up to 5 years, higher serum levels of GGT were associated with lower hazard for transplant-free survival. Serum level of GGT at 12 months after treatment higher than 3.2-fold the upper limit of normal (ULN) identified patients who required liver transplantation or with liver-related death at 10 years with an area under the receiver operating characteristic curve of 0.70. The risk of liver transplantation or liver-related death in patients with serum level of GGT above 3.2-fold the ULN, despite level of ALP lower than 1.5-fold the ULN, was higher compared to patients with level of GGT lower than 3.2-fold the ULN and level of ALP lower than 1.5-fold the ULN (P < .05). Including information on level of GGT increased the prognostic value of the Globe score., Conclusions: Serum level of GGT can be used to identify patients with PBC at risk for liver transplantation or death, and increase the prognostic value of ALP measurement. Our findings support the use of GGT as primary clinical endpoint in clinical trials. In patients with low serum level of ALP, a high level of GGT identifies those who might require treatment of metabolic disorders or PBC treatment escalation., (Copyright © 2021 AGA Institute. Published by Elsevier Inc. All rights reserved.)

Background & Aims: Patients usually receive a diagnosis of primary biliary cholangitis (PBC) at an early stage, based on biochemical analyses. We investigated the proportion of patients who progress to moderate or advanced PBC and factors associated with progression and patient survival., Methods: We obtained data from 1615 patients (mean age, 55.4 y) with early stage PBC (based on their normal levels of albumin and bilirubin), collected at the time of initial evaluation or treatment, from the Global PBC Study Group database (comprising patients at 19 liver centers in North American and European countries). We collected data from health care evaluations on progression to moderate PBC (abnormal level of bilirubin or albumin) or advanced-stage PBC (abnormal level of both). The median follow-up time was 7.9 years. The composite end point was decompensation, hepatocellular carcinoma, liver transplantation, or death., Results: Of the 1615 patients identified with early stage PBC, 904 developed moderate PBC and 201 developed advanced disease over the study period. The proportions of patients who transitioned to moderate PBC at 1, 3, and 5 years were 12.9%, 30.2%, and 45.8%. The proportions of these patients who then transitioned to advanced PBC at 1, 3, and 5 years later were 3.4%, 12.5%, and 16.0%, respectively. During the follow-up period, 236 patients had a clinical event. The proportions of patients with moderate PBC and event-free survival were 97.9%, 95.1%, and 91.5% at 1, 3, and 5 years, respectively, and the proportions of patients with advanced PBC and event-free survival were 90.6%, 71.2%, and 58.3% at 1, 3, and 5 years later, respectively. Variables associated with transition from early to moderate PBC included baseline levels of bilirubin, albumin, and alkaline phosphatase; aspartate to alanine aminotransferase ratio; platelet count; and treatment with ursodeoxycholic acid. Transitions from early to moderate PBC and from moderate to advanced PBC were associated with higher probabilities of a clinical event (time-dependent hazard ratios, 3.0; 95% CI, 2.0-4.5; and 4.6; 95% CI, 3.5-6.2)., Conclusions: Approximately half of patients with early stage PBC progress to a more severe stage within 5 years. Progression is associated with an increased risk of a clinical event, so surveillance is important for patients with early stage PBC., (Copyright © 2020 AGA Institute. Published by Elsevier Inc. All rights reserved.)

Background: Fibrosis stage predicts prognosis in patients with chronic liver disease independent of aetiology, although its precise role in risk stratification in patients with primary biliary cholangitis (PBC) remains undefined., Aim: To assess the utility of baseline fibrosis stage in predicting long-term outcomes in the context of biochemical risk stratification METHODS: In a large and globally representative cohort of patients with PBC, liver biopsies performed from 1980 to 2014 were evaluated. The predictive ability of histologic fibrosis stage in addition to treatment response at 1 year (Toronto/Paris-II criteria), as well as non-invasive markers of fibrosis (AST/ALT ratio [AAR], AST to platelet ratio index [APRI], FIB-4), for transplant-free survival was assessed with Cox proportional-hazards models., Results: There were 1828 patients with baseline liver biopsy. Advanced histologic fibrosis (stage 3/4) was an independent predictor of survival in addition to non-invasive measures of fibrosis with the hazard ratios ranging from 1.59 to 2.73 (P < .001). Patients with advanced histologic fibrosis stage had worse survival despite biochemical treatment response, with a 10-year survival of 76.0%-86.6% compared to 94.5%-95.1% depending on the treatment response criteria used. Poor correlations were observed between non-invasive measures of fibrosis and histologic fibrosis stage., Conclusion: Assessment of fibrosis stage grants prognostic value beyond biochemical treatment response at 1 year. This highlights the need to incorporate fibrosis stage in individual risk stratification in patients with PBC, partly to identify those that may derive benefit from novel therapies., (© 2019 John Wiley & Sons Ltd.)

Background & Aims: Primary biliary cholangitis (PBC) predominantly affects middle-aged women; there are few data on disease phenotypes and outcomes of PBC in men and younger patients. We investigated whether differences in sex and/or age at the start of ursodeoxycholic acid (UDCA) treatment are associated with response to therapy, based on biochemical markers, or differences in transplant-free survival., Methods: We performed a longitudinal retrospective study of 4355 adults in the Global PBC Study cohort, collected from 17 centers across Europe and North America. Patients received a diagnosis of PBC from 1961 through 2014. We evaluated the effects of sex and age on response to UDCA treatment (based on GLOBE score) and transplant-free survival using logistic regression and Cox regression analyses, respectively., Results: Male patients were older at the start of treatment (58.3±12.1 years vs 54.3±11.6 years for women; P<.0001) and had higher levels of bilirubin and lower circulating platelet counts (P<.0001). Younger patients (45 years or younger) had increased serum levels of transaminases than older patients (older than 45 years). Patients older than 45 years at time of treatment initiation had increased odds of a biochemical response to UDCA therapy, based on GLOBE score, compared to younger patients. The greatest odds of response to UDCA were observed in patients older than 65 years (odds ratio compared to younger patients 45 years or younger, 5.48; 95% CI, 3.92-7.67; P<.0001). Risk of liver transplant or death (compared to a general population matched for age, sex, and birth year) decreased significantly with advancing age: hazard ratio for patients 35 years or younger, 14.59 (95% CI, 9.66-22.02) vs hazard ratio for patients older than 65 years, 1.39 (95% CI, 1.23-1.57) (P<.0001). On multivariable analysis, sex was not independently associated with response or transplant-free survival., Conclusion: In longitudinal analysis of 4355 adults in the Global PBC Study, we associated patient age, but not sex, with response to UDCA treatment and transplant-free survival. Younger age at time of treatment initiation is associated with increased risk of treatment failure, liver transplant, and death., (Copyright © 2019 AGA Institute. Published by Elsevier Inc. All rights reserved.)

The GLOBAL Primary Biliary Cholangitis (PBC) Study Group and United Kingdom-PBC (UK-PBC) Consortium have demonstrated that dichotomous response criteria are not as accurate as continuous equations at predicting mortality or liver transplantation in PBC. The aim of this analysis was to assess the clinical utility of the GLOBE and UK-PBC risk scores using data from POISE, a phase 3 trial investigating obeticholic acid (OCA) in patients with PBC. Data (N = 216) at baseline and month 12 were used to calculate the GLOBE and UK-PBC risk scores to assess the projected change in risk with OCA versus placebo. Additionally, the benefit of OCA was assessed in patients not meeting the POISE primary endpoint. Both the GLOBE and UK-PBC risk scores predicted a significant reduction in long-term risk of death and liver transplantation after OCA treatment ( P < 0.0001). The differences in the relative risk reduction from baseline in the 10-year event risk after 1 year for OCA 10 mg versus placebo was 26% (GLOBE) and 37% (UK-PBC). The scores also predicted a significantly decreased risk in patients treated with OCA who did not meet POISE response criteria after 1 year of treatment compared to an increased risk with placebo ( P < 0.0001). Conclusion: This analysis demonstrates the use of the GLOBE and UK-PBC risk scores to assess risk reduction of a cohort treated with OCA. While validation of this risk reduction in studies with clinical outcomes is needed, this study highlights the potential use of these scores in individualizing risk prediction in PBC both in clinical practice and therapeutic trials. ( Hepatology Communications 2018;2:683-692).

Inflammation is a crucial defense mechanism that protects the body from the devastating effects of invading pathogens. However, an unrestrained inflammatory reaction may result in systemic manifestations with dire consequences to the host. The extent of activation of the inflammatory response is tightly regulated through immunological and neural pathways. Previously, we demonstrated that cholinergic stimulation confers enhanced protection in experimental animals orally infected with virulent Salmonella enterica serovar Typhimurium. In this study, we investigated the mechanism by which this enhanced protection takes place. Cholinergic stimulation was induced by a 3-week pretreatment with paraoxon, a highly specific acetylcholinesterase (AChE) inhibitor. This treatment enhanced host survival following oral-route infection and this correlated with significantly reduced bacterial load in systemic target organs. Enhanced protection was not due to increased gut motility or rapid bacterial clearance from the gastrointestinal tract. Moreover, protection against bacterial infection was not evident when the animals were infected systemically, suggesting that acetylcholine-mediated protective effect was mostly confined to the gut mucosal tissue. In vivo imaging demonstrated a more localized infection and delay in bacterial dissemination into systemic organs in mice pretreated with paraoxon. Morphological analysis of the small intestine (ileum) showed that AChE inhibition induced the degranulation of goblet cells and Paneth cells, two specialized secretory cells involved in innate immunity. Our findings demonstrate a crucial pathway between neural and immune systems that acts at the mucosal interface to protect the host against oral pathogens.

Background: The fibrous structure of the myometrium has previously been characterised at high resolutions in small tissue samples (< 100 mm3) and at low resolutions (∼500 μm per voxel edge) in whole-organ reconstructions. However, no high-resolution visualisation of the myometrium at the organ level has previously been attained., Methods and Results: We have developed a technique to reconstruct the whole myometrium from serial histological slides, at a resolution of approximately 50 μm per voxel edge. Reconstructions of samples taken from human and rat uteri are presented here, along with histological verification of the reconstructions and detailed investigation of the fibrous structure of these uteri, using a range of tools specifically developed for this analysis. These reconstruction techniques enable the high-resolution rendering of global structure previously observed at lower resolution. Moreover, structures observed previously in small portions of the myometrium can be observed in the context of the whole organ. The reconstructions are in direct correspondence with the original histological slides, which allows the inspection of the anatomical context of any features identified in the three-dimensional reconstructions., Conclusions and Significance: The methods presented here have been used to generate a faithful representation of myometrial smooth muscle at a resolution of ∼50 μm per voxel edge. Characterisation of the smooth muscle structure of the myometrium by means of this technique revealed a detailed view of previously identified global structures in addition to a global view of the microarchitecture. A suite of visualisation tools allows researchers to interrogate the histological microarchitecture. These methods will be applicable to other smooth muscle tissues to analyse fibrous microarchitecture.

Background: Criteria assessing biochemical response to ursodeoxycholic acid (UDCA) are established risk stratification tools in primary biliary cholangitis (PBC). We aimed to evaluate to what extent liver tests influenced patient management during a three decade period, and whether this changed over time., Methods: 851 Dutch PBC patients diagnosed between 1988 and 2012 were reviewed to assess patient management in relation to liver test results during UDCA treatment. To do so, biochemical response at one year was analysed retrospectively according to Paris-1 criteria., Results: Response was assessable for 687/851 (81%) patients; 157/687 non-responders. During a follow-up of 8.8 years (IQR 4.8-13.9), 141 died and 30 underwent liver transplantation. Transplant-free survival of non-responders (60%) was significantly worse compared with responders (87%) (p < 0.0001). Management was modified in 46/157 (29%) non-responders. The most frequent change observed, noted in 26/46 patients, was an increase in UDCA dosage. Subsequently, 9/26 (35%) non-responders became responders within the next two years. Steroid treatment was started in one patient; 19 patients were referred to a tertiary centre. No trend towards more frequent changes in management over time was observed (p = 0.10)., Conclusion: Changes in medical management occurred in a minority of non-responders. This can largely be explained by the lack of accepted response criteria and of established second-line treatments for PBC. Nevertheless, the observation that response-guided management did not increase over time suggests that awareness of the concept of biochemical response requires further attention,particularly since new treatment options for PBC will soon become available.

The pregnant uterus is a smooth muscle organ whose pattern of contraction is dictated by the propagation of electrical impulses. Such electrical activity may originate from one or more pacemakers, but the location of these sites has not yet been determined. To detect the location of the pacemaker in the gravid uterus, two approaches were used: 1) determine the site from where the contraction started using isolated uteri from the pregnant guinea pig, and videotape their contractions; and 2) record, in isolated uteri from pregnant term rats, with 240 extracellular electrodes simultaneously, and determine where the electrical bursts started. In both the contractile and electrophysiological experiments, there was not a single, specific pacemaker area. However, most contractions (guinea pig 87%) and bursts (rat 76%) started close to the mesometrial border (mean 2.7 ± 4.0 mm SD in guinea pigs and 1.3 ± 1.4 mm in rats). In addition, in the rat, most sites of initiations were located closer to the ovarial end of the horn (mean distance from the ovarial end 6.0 ± 6.2 mm SD), whereas such an orientation was not seen in the guinea pig. In both guinea pig and rat uteri at term, there is not one specific pacemaker area. Rather, contractile and electrical activity may arise from any site, with the majority starting close to the mesometrial border. Furthermore, in the rat, most activities started at the ovarial end of the horn. This may suggest a slightly different pattern of contraction in both species., (Copyright © 2015 the American Physiological Society.)

Background & Aims: Approaches to risk stratification for patients with primary biliary cirrhosis (PBC) are limited, single-center based, and often dichotomous. We aimed to develop and validate a better model for determining prognoses of patients with PBC., Methods: We performed an international, multicenter meta-analysis of 4119 patients with PBC treated with ursodeoxycholic acid at liver centers in 8 European and North American countries. Patients were randomly assigned to derivation (n = 2488 [60%]) and validation cohorts (n = 1631 [40%]). A risk score (GLOBE score) to predict transplantation-free survival was developed and validated with univariate and multivariable Cox regression analyses using clinical and biochemical variables obtained after 1 year of ursodeoxycholic acid therapy. Risk score outcomes were compared with the survival of age-, sex-, and calendar time-matched members of the general population. The prognostic ability of the GLOBE score was evaluated alongside those of the Barcelona, Paris-1, Rotterdam, Toronto, and Paris-2 criteria., Results: Age (hazard ratio = 1.05; 95% confidence interval [CI]: 1.04-1.06; P < .0001); levels of bilirubin (hazard ratio = 2.56; 95% CI: 2.22-2.95; P < .0001), albumin (hazard ratio = 0.10; 95% CI: 0.05-0.24; P < .0001), and alkaline phosphatase (hazard ratio = 1.40; 95% CI: 1.18-1.67; P = .0002); and platelet count (hazard ratio/10 units decrease = 0.97; 95% CI: 0.96-0.99; P < .0001) were all independently associated with death or liver transplantation (C-statistic derivation, 0.81; 95% CI: 0.79-0.83, and validation cohort, 0.82; 95% CI: 0.79-0.84). Patients with risk scores >0.30 had significantly shorter times of transplant-free survival than matched healthy individuals (P < .0001). The GLOBE score identified patients who would survive for 5 years and 10 years (responders) with positive predictive values of 98% and 88%, respectively. Up to 22% and 21% of events and nonevents, respectively, 10 years after initiation of treatment were correctly reclassified in comparison with earlier proposed criteria. In subgroups of patients aged <45, 45-52, 52-58, 58-66, and ≥66 years, age-specific GLOBE-score thresholds beyond which survival significantly deviated from matched healthy individuals were -0.52, 0.01, 0.60, 1.01 and 1.69, respectively. Transplant-free survival could still be accurately calculated by the GLOBE score with laboratory values collected at 2-5 years after treatment., Conclusions: We developed and validated scoring system (the GLOBE score) to predict transplant-free survival of ursodeoxycholic acid-treated patients with PBC. This score might be used to select strategies for treatment and care., (Copyright © 2015 AGA Institute. Published by Elsevier Inc. All rights reserved.)

Aim: To evaluate and characterize motility patterns from small intestinal gut segments depending on different perfusion media and pressures., Methods: Experiments were carried out in a custom designed perfusion chamber system to validate and standardise the perfusion technique used. The perfusion chamber was built with a transparent front wall allowing for optical motility recordings and a custom made fastener to hold the intestinal segments. Experiments with different perfusion and storage media combined with different luminal pressures were carried out to evaluate the effects on rat small intestine motility. Software tools which enable the visualization and characterization of intestinal motility in response to different stimuli were used to evaluate the videotaped experiments. The data collected was presented in so called heatmaps thus providing a concise overview of form and strength of contractility patterns. Furthermore, the effect of different storage media on tissue quality was evaluated. Haematoxylin-Eosin stainings were used to compare tissue quality depending on storage and perfusion mode., Results: Intestinal motility is characterized by different repetitive motility patterns, depending on the actual situation of the gut. Different motility patterns could be recorded and characterized depending on the perfusion pressure and media used. We were able to describe at least three different repetitive patterns of intestinal motility in vitro. Patterns with an oral, anal and oro-anal propagation direction could be recorded. Each type of pattern finalized its movement with or without a subsequent distension of the wavefront. Motility patterns could clearly be distinguished in heatmap diagrams. Furthermore undirected motility could be observed. The quantity of the different patterns varies and is highly dependent on the perfusion medium used. Tissue preservation varies depending on the perfusion medium utilized, therefore media with a simple composition as Tyrode solution can only be recommended for short time experiments. The more complex media, MEM-HEPES medium and especially AQIX(®) RS-I tissue preservation reagent preserved the tissue much better during perfusion., Conclusion: Perfusion media have to be carefully chosen considering type and duration of the experiments. If excellent tissue quality is required, complex media are favorable. Perfusion pressure is also of great importance due to the fact that a minimum amount of luminal pressure seems to be necessary to trigger intestinal contractions.

Background & Aims: Noninvasive surrogate end points of long-term outcomes of patients with primary biliary cirrhosis (PBC) are needed to monitor disease progression and evaluate potential treatments. We performed a meta-analysis of individual patient data from cohort studies to evaluate whether patients' levels of alkaline phosphatase and bilirubin correlate with their outcomes and can be used as surrogate end points., Methods: We performed a meta-analysis of data from 4845 patients included in 15 North American and European long-term follow-up cohort studies. Levels of alkaline phosphatase and bilirubin were analyzed in different settings and subpopulations at different time points relative to the clinical end point (liver transplantation or death)., Results: Of the 4845 patients, 1118 reached a clinical end point. The median follow-up period was 7.3 years; 77% survived for 10 years after study enrollment. Levels of alkaline phosphatase and bilirubin measured at study enrollment (baseline) and each year for 5 years were strongly associated with clinical outcomes (lower levels were associated with longer transplant-free survival). At 1 year after study enrollment, levels of alkaline phosphatase that were 2.0 times the upper limit of normal (ULN) best predicted patient outcome (C statistic, 0.71) but not significantly better than other thresholds. Of patients with alkaline phosphatase levels ≤ 2.0 times the ULN, 84% survived for 10 years compared with 62% of those with levels >2.0 times the ULN (P < .0001). Absolute levels of alkaline phosphatase 1 year after study enrollment predicted patient outcomes better than percentage change in level. One year after study enrollment, a bilirubin level 1.0 times the ULN best predicted patient transplant-free survival (C statistic, 0.79). Of patients with bilirubin levels ≤ 1.0 times the ULN, 86% survived for 10 years after study enrollment compared with 41% of those with levels >1.0 times the ULN (P < .0001). Combining levels of alkaline phosphatase and bilirubin increased the ability to predict patient survival times. We confirmed the predictive value of alkaline phosphatase and bilirubin levels in multiple subgroups, such as patients who had not received treatment with ursodeoxycholic acid, and at different time points after study enrollment., Conclusions: Levels of alkaline phosphatase and bilirubin can predict outcomes (liver transplantation or death) of patients with PBC and might be used as surrogate end points in therapy trials., (Copyright © 2014 AGA Institute. Published by Elsevier Inc. All rights reserved.)

There is little knowledge about macroscopic electrical propagation in the wall of the urinary bladder. Recording simultaneously from a large number of extracellular electrodes is one technology that could be used to study the patterns of macroscopic electrical propagations. The urinary bladders from 14 guinea pigs were isolated and placed in an organ bath. A 16 × 4-electrode array was positioned at various sites on the serosal bladder surface, and recordings were performed at different intravesical volumes. In four experiments, carbachol (CCH; 10(-6) M), nifedipine (10 mM), or tetrodotoxin (TTX; 10(-6) M) was added to the superfusing fluid. After the experiments, the extracellular signals were analyzed and propagation maps were constructed. Electrical waves were detected at all sites on the bladder surface and propagated for a limited distance before terminating spontaneously. The majority of waves (>90%) propagated in the axial direction (i.e., from dome to base or vice versa). An increase in vesicle volume significantly decreased the conduction velocity (from 4.9 ± 1.5 to 2.7 ± 0.7 cm/s; P < 0.05). CCH increased, nifedipine decreased, while TTX had little effect on electrical activities. In addition, a new electrical phenomenon, termed a "patch," was discovered whereby a simultaneous electrical deflection was detected across an area of the bladder surface. Two types of electrical activities were detected on the bladder surface: 1) electrical waves propagating preferentially in the axial direction and 2) electrical patches. The propagating electrical waves could form the basis for local spontaneous contractions in the bladder during the filling phase., (Copyright © 2014 the American Physiological Society.)

Primary biliary cirrhosis (PBC) is a slowly progressive autoimmune liver disease that may ultimately result in liver failure and premature death. Predicting outcome is of key importance in clinical management and an essential requirement for patients counselling and timing of diagnostic and therapeutic interventions. The following factors are associated with progressive disease and worse outcome: young age at diagnosis, male gender, histological presence of cirrhosis, accelerated marked uctopenia in relation to the amount of fibrosis, high serum bilirubin, low serum albumin levels, high serum alkaline phosphatase levels, esophageal varices, hepatocellular carcinoma (HCC) and lack of biochemical response to ursodeoxycholic acid (UDCA). The prognostic significance of symptoms at diagnosis is uncertain. UDCA therapy and liver transplantation have a significant beneficial effect on the outcome of the disease. The Mayo risk score in PBC can be used for estimating individual prognosis. The Newcastle Varices in PBC Score may be a useful clinical tool to predict the risk for development of esophageal varices. Male gender, cirrhosis and non-response to UDCA therapy in particular, are risk factors for development of HCC.

Mutations in SCN5A, the gene encoding the pore-forming subunit of cardiac Na(+) channels, cause a spectrum of arrhythmic syndromes. Of these, sinoatrial node (SAN) dysfunction occurs in patients with both loss- and gain-of-function SCN5A mutations. We explored for corresponding alterations in SAN function and intracardiac conduction and clarified possible mechanisms underlying these in an established mouse long QT syndrome type 3 model carrying a mutation equivalent to human SCN5A-ΔKPQ. Electrophysiological characterizations of SAN function in living animals and in vitro sinoatrial preparations were compared with cellular SAN and two-dimensional tissue models exploring the consequences of Scn5a+/ΔKPQ mutations. Scn5a+/ΔKPQ mice showed prolonged electrocardiographic QT and corrected QT intervals confirming long QT phenotypes. They showed frequent episodes of sinus bradycardia, sinus pause/arrest, and significantly longer sinus node recovery times, suggesting compromised pacemaker activity compared with wild-type mice. Electrocardiographic waveforms suggested depressed intra-atrial, atrioventricular node, and intraventricular conduction in Scn5a+/ΔKPQ mice. Isolated Scn5a+/ΔKPQ sinoatrial preparations similarly showed lower mean intrinsic heart rates and overall slower conduction through the SAN to the surrounding atrium than did wild-type preparations. Computer simulations of both single SAN cells as well as two-dimensional SAN-atrial models could reproduce the experimental observations of impaired pacemaker and sinoatrial conduction in terms of changes produced by both augmented tail and reduced total Na(+) currents, respectively. In conclusion, the gain-of-function long QT syndrome type 3 murine Scn5a+/ΔKPQ cardiac system, in overlap with corresponding features reported in loss-of-function Na(+) channel mutations, shows compromised SAN pacemaker and conduction function explicable in modeling studies through a combination of augmented tail and reduced peak Na(+) currents.

In a few recent studies, the presence of arrhythmias based on reentry and circus movement of the slow wave have been shown to occur in normal and diseased stomachs. To date, however, reentry has not been demonstrated before in any other part of the gastrointestinal system. No animals had to be killed for this study. Use was made of materials obtained during the course of another study in which 11 rats were treated with streptozotocin and housed with age-matched controls. After 3 and 7 mo, segments of duodenum, jejunum, and ileum were isolated and positioned in a tissue bath. Slow wave propagation was recorded with 121 extracellular electrodes. After the experiment, the propagation of the slow waves was reconstructed. In 10 of a total of 66 intestinal segments (15%), a circus movement of the slow wave was detected. These reentries were seen in control (n = 2) as well as in 3-mo (n = 2) and 7-mo (n = 6) diabetic rats. Local conduction velocities and beat-to-beat intervals during the reentries were measured (0.42 ± 0.15 and 3.03 ± 0.67 cm/s, respectively) leading to a wavelength of 1.3 ± 0.5 cm and a circuit diameter of 4.1 ± 1.5 mm. This is the first demonstration of a reentrant arrhythmia in the small intestine of control and diabetic rats. Calculations of the size of the circuits indicate that they are small enough to fit inside the intestinal wall. Extrapolation based on measured velocities and rates indicate that reentrant arrhythmias are also possible in the distal small intestine of larger animals including humans.

The number of myenteric interstitial cells of Cajal (ICC-MY), responsible for the generation and propagation of the slow wave in the small intestine, has been shown to decrease in diabetes, suggesting impairment of slow-wave (SW) propagation and related motility. To date, however, this expected decrease in SW propagation has neither been recorded nor analysed. Eleven rats were treated with streptozotocin and housed in pairs with 11 age-matched control animals. After 3 or 7 months, segments of duodenum, jejunum and ileum were isolated and divided into two parts. One part was processed for immediate freezing, cryosectioning and immunoprobing using anti-c-Kit antibody to quantify ICC-MY. The second part was superfused in a tissue bath, and SW propagation was recorded with 121 extracellular electrodes. In addition, a cellular automaton was developed to study the effects of increasing the number of inactive cells on overall propagation. The number of ICC-MY was significantly reduced after 3 months of diabetes, but rebounded to control levels after 7 months of diabetes. Slow-wave frequencies, velocities and extracellular amplitudes were unchanged at any stage of diabetes. The cellular automaton showed that SW velocity was not linearly related to the number of inactive cells. The depletion of ICC-MY is not as severe as is often assumed and in fact may rebound after some time. In addition, at least in the streptozotocin model, the initial reduction in ICC-MY is not enough to affect SW propagation. Diabetic intestinal dysfunction may therefore be more affected by impairments of other systems, such as the enteric system or the muscle cells.

Slow waves coordinate gastric motility, and abnormal slow-wave activity is thought to contribute to motility disorders. The current understanding of normal human gastric slow-wave activity is based on extrapolation from data derived from sparse electrode recordings and is therefore potentially incomplete. This study employed high-resolution (HR) mapping to reevaluate human gastric slow-wave activity. HR mapping was performed in 12 patients with normal stomachs undergoing upper abdominal surgery, using flexible printed circuit board (PCB) arrays (interelectrode distance 7.6 mm). Up to six PCBs (192 electrodes; 93 cm(2)) were used simultaneously. Slow-wave activity was characterized by spatiotemporal mapping, and regional frequencies, amplitudes, and velocities were defined and compared. Slow-wave activity in the pacemaker region (mid to upper corpus, greater curvature) was of greater amplitude (mean 0.57 mV) and higher velocity (8.0 mm/s) than the corpus (0.25 mV, 3.0 mm/s) (P < 0.001) and displayed isotropic propagation. A marked transition to higher amplitude and velocity activity occurred in the antrum (0.52 mV, 5.9 mm/s) (P < 0.001). Multiple (3-4) wavefronts were found to propagate simultaneously in the organoaxial direction. Frequencies were consistent between regions (2.83 +/- 0.35 cycles per min). HR mapping has provided a more complete understanding of normal human gastric slow-wave activity. The pacemaker region is associated with high-amplitude, high-velocity activity, and multiple wavefronts propagate simultaneously. These data provide a baseline for future HR mapping studies in disease states and will inform noninvasive diagnostic strategies.

Gastric pacing has been investigated as a potential treatment for gastroparesis. New pacing protocols are required to improve symptom and motility outcomes; however, research progress has been constrained by a limited understanding of the effects of electrical stimulation on slow-wave activity. This study introduces high-resolution (HR) "entrainment mapping" for the analysis of gastric pacing and presents four demonstrations. Gastric pacing was initiated in a porcine model (typical amplitude 4 mA, pulse width 400 ms, period 17 s). Entrainment mapping was performed using flexible multielectrode arrays (

Slow waves are known to originate orally in the stomach and to propagate toward the antrum, but the exact location of the pacemaker and the precise pattern of propagation have not yet been studied. Using assemblies of 240 extracellular electrodes, simultaneous recordings of electrical activity were made on the fundus, corpus, and antrum in open abdominal anesthetized dogs. The signals were analyzed off-line, pathways of slow wave propagation were reconstructed, and slow wave velocities and amplitudes were measured. The gastric pacemaker is located in the upper part of the fundus, along the greater curvature. Extracellularly recorded slow waves in the pacemaker area exhibited large amplitudes (1.8 +/- 1.0 mV) and rapid velocities (1.5 +/- 0.9 cm/s), whereas propagation in the remainder of the fundus and in the corpus was slow (0.5 +/- 0.2 cm/s) with low-amplitude waveforms (0.8 +/- 0.5 mV). In the antrum, slow wave propagation was fast (1.5 +/- 0.6 cm/s) with large amplitude deflections (2.0 +/- 1.3 mV). Two areas were identified where slow waves did not propagate, the first in the oral medial fundus and the second distal in the antrum. Finally, recordings from the entire ventral surface revealed the presence of three to five simultaneously propagating slow waves. High resolution mapping of the origin and propagation of the slow wave in the canine stomach revealed areas of high amplitude and rapid velocity, areas with fractionated low amplitude and low velocity, and areas with no propagation; all these components together constitute the elements of a gastric conduction system.

Peristaltic motor activity of the gut is an essential activity to sustain life. In each gut organ, a multitude of overlapping mechanisms has developed to acquire the ability of coordinated contractile activity under a variety of circumstances and in response to a variety of stimuli. The presence of several simultaneously operating control systems is a challenge for investigators who focus on the role of one particular control activity since it is often not possible to decipher which control systems are operating or dominant in a particular situation. A crucial advantage of multiple control systems is that gut motility control can withstand injury to one or more of its components. Our efforts to increase understanding of control mechanism are not helped by recent attempts to eliminate proven control systems such as interstitial cells of Cajal (ICC) as pacemaker cells, or intrinsic sensory neurons, nor does it help to view peristalsis as a simple reflex. This review focuses on the role of ICC as slow-wave pacemaker cells and places ICC into the context of other control mechanisms, including control systems intrinsic to smooth muscle cells. It also addresses some areas of controversy related to the origin and propagation of pacemaker activity. The urge to simplify may have its roots in the wish to see the gut as a consequence of a single perfect design experiment whereas in reality the control mechanisms of the gut are the messy result of adaptive changes over millions of years that have created complementary and overlapping control systems. All these systems together reliably perform the task of moving and mixing gut content to provide us with essential nutrients.

Background & Aims: Gastric arrhythmias occur in humans and experimental animals either spontaneously or induced by drugs or diseases. However, there is no information regarding the origin or the propagation patterns of the slow waves that underlie such arrhythmias., Methods: To elucidate this, simultaneous recordings were made on the antrum and the distal corpus during tachygastrias in open abdominal anesthetized dogs using a 240 extracellular electrode assembly. After the recordings, the signals were analyzed, and the origin and path of slow wave propagations were reconstructed., Results: Several types of arrhythmias could be distinguished, including (1) premature slow waves (25% of the arrhythmias), (2) single aberrant slow waves (4%), (3) bursts (18%), (4) regular tachygastria (11%), and (5) irregular tachygastria (10%). During regular tachygastria, rapid, regular slow waves emerged from the distal antrum or the greater curvature, whereas, during irregular tachygastria, numerous variations occurred in the direction of propagation, conduction blocks, focal activity, and re-entry. In 12 cases, the arrhythmia was initiated in the recorded area. In each case, after a normal propagating slow wave, a local premature slow wave occurred in the antrum. These premature slow waves propagated in various directions, often describing a single or a double loop that re-entered several times, thereby initiating additional slow waves., Conclusions: Gastric arrhythmias resemble those in the heart and share many common features such as focal origin, re-entry, circular propagation, conduction blocks, and fibrillation-like behavior.

The aim of this study was to characterize the role of the late Na+ current (I(Na,L)) as a mechanism for induction of both tachy and bradyarrhythmias in murine heart and sino-atrial node tissue. The sea anemone toxin ATX-II and ranolazine were used to increase and inhibit, respectively, I(Na,L). In sixteen hearts studied, exposure to 1-10nM ATX-II caused a slowing of intrinsic heart rate and prolongations of the P-R and QT intervals, the duration of the monophasic action potential, and the sinus node recovery time, accompanied by frequent occurrences of early after depolarisations, delayed after depolarisations and rapid, repetitive ventricular tachy and sino-atrial bradyarrhythmias. ATX-II also slowed sinus node pacemaking, and induced bradycardic arrhythmias in isolated sino-atrial preparations (n=5). The ATX-II-induced alteration of electrophysiological properties and occurrence of arrhythmic events were significantly attenuated by 10 microM ranolazine in intact hearts (n=11) and isolated sino-atrial preparations (n=5). In conclusion, the I(Na,L) enhancer ATX-II causes both tachy and bradyarrhythmias in the murine heart, and these arrhythmias are markedly attenuated by the I(Na,L) blocker, ranolazine (10 microM). The results suggest that I(Na,L) blockade may be the mechanism underlying the reductions of both brady and tachyarrhythmias by ranolazine that were observed during the MERLIN-TIMI clinical outcomes trial.

Previous studies have reported on propagation of individual spikes in isolated segments of the pregnant uterus, but there is no information on patterns of spike propagation in the intact organ. There is also no information on propagation of myometrial burst. The aim of this study was to record, at high resolution, patterns of propagation of electrical activities in the pregnant uterus. Sixteen timed-pregnant guinea pigs were euthanized at term, and their uteruses isolated. Fetuses were removed and replaced by an equal amount of Tyrode. A 240-electrode array was positioned at various locations along the organ, all signals were recorded simultaneously, and the electrical propagations were reconstructed. In the intact pregnant uterus at term, spikes propagated with high velocity in longitudinal (6.8 +/- 2.4 cm/s) and slower velocity in circular direction (2.8 +/- 1.0 cm/s; P < 0.01). Direction of propagation and frequency of activity were highly variable but showed similar patterns at the ovary or cervical end and along the anterior, posterior, and antimesometrial borders. Along mesometrium, spike propagation was sparse and fractionated. Migration of burst (0.6 +/- 0.4 cm/s) was significantly much slower than that of individual spikes (P < 0.001). Initial burst activity was located at variable locations along the ovarial end of the antimesometrial border, while the latest excitation occurred at the cervical end (1.2 +/- 0.9 min). In conclusion, high resolution electrical mapping of the intact pregnant uterus reveals fundamental properties in spatial and temporal patterns of spike and burst propagation that determine the contraction of the organ.

The pattern of propagation of slow waves in the small intestine is not clear. Specifically, it is not known whether propagation is determined by a single dominant ICC-MP (Interstitial cells of Cajal located in the Myenteric Plexus) pacemaker unit or whether there are multiple active pacemakers. To determine this pattern of propagation, waveforms were recorded simultaneously from 240 electrodes distributed along the whole length of the intact isolated feline small intestine. After the experiments, the propagation patterns of successive individual slow waves were analysed. In the intact small intestine, there was only a single slow wave pacemaker unit active, and this was located at or 6-10 cm from the pyloric junction. From this site, slow waves propagated in the aboral direction at gradually decreasing velocities. The majority of slow waves (73%) reached the ileocaecal junction while the remaining waves were blocked. Ligation of the intestine at one to four locations led to: (a) decrease in the distal frequencies; (b) disappearance of distal propagation blocks; (c) increase in velocities; (d) emergence of multiple and unstable pacemaker sites; and (e) propagation from these sites in the aboral and oral directions. In conclusion, in the quiescent feline small intestine a single pacemaker unit dominates the organ, with occasional propagation blocks of the slow waves, thereby producing the well-known frequency gradient.

Background: Spatio-temporal (ST) maps provide a method for visualizing a temporally evolving and spatially varying field, which can also be used in the analysis of gastrointestinal motility. However, it is not always clear what the underlying contractions are that are represented in ST maps and whether some types of contractions are poorly represented or possibly not at all., Methods: To analyze the translation from stationary or propagating rhythmic contractions of the intestine to ST maps, a simulation program was used to represent different patterns of intestinal contraction and to construct their corresponding ST maps. A number of different types of contractions were simulated and their ST maps analyzed., Results: Circular strong contractions were well represented in ST maps as well as their frequency and velocity. Longitudinal contractions were not detected at all. Combinations of circular and longitudinal contractions were, to a limited extent detectable at a point in space and time. The method also enabled the construction of specific ST-patterns to mimic real-life ST maps and the analysis of the corresponding contraction patterns., Conclusion: Spatio-temporal simulations provide a method to understand, teach and analyze ST maps. This approach could be useful to determine characteristics of contractions under a variety of circumstances.

Since the development of knockout animals, the mouse has become an important model to study gastrointestinal motility. However, little information is available on the electrical and contractile activities induced by distension in the murine small intestine. Spatiotemporal electrical mapping and mechanical recordings were made from isolated intestinal segments from different regions of the murine small intestine during distension. The electrical activity was recorded with 16 extracellular electrodes while motility was assessed simultaneously by tracking the border movements with a digital camera. Distension induced propagating oscillatory contractions in isolated intestinal segments. These propagating contractions were dictated by the underlying propagating slow wave with superimposed spikes. The frequencies, velocities, and direction of the propagating oscillations strongly correlated with the frequencies (r = 0.86), velocities (r = 0.84), and direction (r = 1) of the electrical slow waves. N(omega)-nitro-L-arginine methyl ester decreased the maximal diameter of the segment and reduced the peak contraction amplitude of the propagating oscillatory contractions, whereas atropine and verapamil blocked the propagating oscillations. Tetrodotoxin had little effect on the maximal diameter and peak contraction amplitude. In conclusion, distension in the murine small intestine does not initiate peristaltic reflexes but induces a propagating oscillatory motor pattern that is determined by propagating slow waves with superimposed spikes. These spikes are cholinergic and calcium dependent.

In contrast to the mechanisms of segmental and peristaltic contractions in the small intestine, not much is known about the mechanism of pendular contractions. High-resolution electrical and mechanical recordings were performed from isolated segments of the rabbit ileum during pendular contractions. The electrical activities were recorded with 32 extracellular electrodes while motility was assessed simultaneously by video tracking the displacements of 20-40 serosal markers. The electrical activities consisted of slow waves, followed by spikes, that propagated in either the aboral or oral direction. The mechanical activity always followed the initial electrical activity, describing a contraction phase in one direction followed by a relaxation phase in the opposite direction. Pendular displacements were always in rhythm with the slow wave, whereas the direction of the displacements was dictated by the origin of the slow wave. If the slow wave propagated aborally, then the pendular displacement occurred in the oral direction, whereas if the slow wave propagated in the oral direction, then the displacement occurred in the aboral direction. In the case of more complex propagation patterns, such as in the area of pacemaking or collision, direction of displacements remained always opposite to the direction of the slow wave. In summary, the direction and pattern of propagation of the slow wave determine the rhythm and the direction of the pendular motility. The well-known variability in pendular movements is caused by the variability in the propagation of the underlying slow wave.

The frequency and propagation velocity of distension-induced peristaltic contractions in the antrum and duodenum are distinctly different and depend on activation of intrinsic excitatory motoneurons as well as pacemaker cells, the interstitial cells of Cajal associated with Auerbach's plexus (ICC-AP). Because ICC are critical for coordination of motor activities along the long axis of many regions in the gut, the role of ICC in antroduodenal coordination was investigated. We used immunohistochemistry, electron microscopy, simultaneous multiple electrical recordings in vitro, and videofluoroscopy in vivo in mice and rats. A strongly reduced number of ICC-AP with loss of network characteristics was observed in a 4-mm area in the rat and a 1-mm area in the mouse pyloric region. The pyloric region showed a slow wave-free gap of 4.1 mm in rats and 1.3 mm in mice. Between antrum and duodenum, there was no interaction of electrical activities and in the absence of gastric emptying, there was no coordination of motor activities. When the pyloric sphincter opened, 2.4 s before the front of the antral wave reached the pylorus, the duodenum distended after receiving gastric content and aboral duodenal peristalsis was initiated, often disrupting other motor patterns. The absence of ICC-AP and slow wave activity in the pyloric region allows the antrum and duodenum to have distinct uncoordinated motor activities. Coordination of aborally propagating peristaltic antral and duodenal activity is initiated by opening of the pylorus, which is followed by distention-induced duodenal peristalsis. Throughout this coordinated motor activity, the pacemaker systems in antrum and duodenum remain independent.

In an open-abdominal anesthetized and fasted canine model of the intact small intestine, the presence, location, shape, and frequency of spike patches were investigated. Recordings were performed with a 240-electrode array (24 x 10, 2-mm interelectrode distance) from several sites sequentially, spanning the whole length of the small intestine. All 240 electrograms were recorded simultaneously during periods of 5 min and were analyzed to reconstruct the origin and propagation of individual spikes. At every level in the small intestine, spikes propagated in all directions before stopping abruptly, thereby activating a circumscribed area termed a "patch." Two types of spikes were found: longitudinal spikes, which propagated predominantly in the longitudinal direction and occurred most often in the duodenum, and a second type, circumferential spikes, which propagated predominantly in the circular direction and occurred much more frequently in the jejunum and ileum. Circumferential spikes conducted faster than longitudinal spikes (17 +/- 6 and 7 +/- 2 cm/s, respectively; P < 0.001). Circumferential spikes originated in >90% of all cases from the antimesenteric border, whereas longitudinal spikes were initiated all around the circumference of the intestinal tube. Finally, the spatial sequence of spike patches after the slow wave was very irregular in the upper part of the intestine but much more regular in the lower part. In conclusion, spikes and spike patches occur throughout the small intestine, whereas their type, sites of origin, extent of propagation, and frequencies of occurrence differ along the length of the small intestine, suggesting differences in local patterns of motility.

The relationship between slow waves and peristaltic reflexes has not been well analyzed. In this study, we have recorded the electrical activity of slow waves together with that generated by spontaneous peristaltic contractions at 240 extracellular sites simultaneously. Recordings were made from five isolated tubular and six sheet segments of feline duodenum superfused in vitro. In all preparations, slow waves propagated as broad wave fronts along the longitudinal axis of the preparation in either the aborad or the orad direction. Electrical potentials recorded during peristalsis (peristaltic waves) also propagated as broad wave fronts in either directions. Peristaltic waves often spontaneously stopped conducting (46%), in contrast to slow waves that never did. Peristaltic waves propagated at a lower velocity than the slow waves (0.98 +/- 0.25 and 1.29 +/- 0.28 cm/s, respectively; P < 0.001; n = 24) and in a direction independent of the preceding slow wave direction (64% in the same direction, 46% in the opposite direction). In conclusion, slow waves and peristaltic waves in the isolated feline duodenum seem to constitute two separate electrical events that may drive two different mechanisms of contraction in the small intestine.

In the small intestines, the major task of the slow wave is to induce mechanical movements in the intestinal wall by generating local calcium spikes. High resolution electrical mapping reveals fundamental differences in propagation between slow waves and calcium spikes. These differences suggest that slow waves and spikes are propagated by different mechanisms through different cell networks.

Asynchrony of spikes has made it difficult to study the spatial and temporal behavior of spikes in the gastrointestinal system. By simultaneously recording from a large number of closely spaced electrodes, we investigated the propagation of individual spikes. Recordings were performed from the serosal surface of the isolated feline duodenum at 240 sites simultaneously. Analysis of the tracings made it possible to reconstruct the propagation of individual spikes. Spikes propagate in the longitudinal and circumferential directions in self-limiting areas or "patches." Conduction within patches may occur in the orad or aborad direction irrespective of the direction of the slow wave. Most of the patches are smaller (<40 mm(2)), although inhomogeneous activation by the preceding slow wave may increase their size. Stimulation by ACh, TTX, or tetraethylammonium does not affect the average patch size but does increase significantly their number and distribution in the duodenum [from 26% (control) to 56%, 61%, and 72%, respectively]. In conclusion, individual spikes activate limited areas or patches in the small intestine, and pharmacological stimulation increases the number and distribution of these patches. In the small intestine, this pattern of activation would induce localized contractions. Contraction could be modulated by the size, number, and distribution of spike patches.

Using the CD-ROM system of MEDLINE, which contains the origins of articles that are published in about 3500 international medical journals, a survey was performed on the medical publications from the six countries in the Gulf Cooperating Council (GCC) over a period of five years (1990-1994). The Kingdom of Saudi Arabia was the largest producer of publications, with approximately 400 papers each year. In the same period the output from Kuwait declined from about 200 to a lower number, an effect probably caused by the invasion. In contrast, the United Arab Emirates, and to a lesser extent the Sultanate of Oman, have shown a growth in their publication record due to the initiation of new medical schools in these two countries. In the six GCC countries, all the colleges of medicine together were responsible for 34% of the total number of publications, hospitals and health centers published 45% of all papers, while non-medical colleges and other institutions published smaller amounts (10% and 11% respectively).

In 30 isolated, spontaneously beating right atrial preparations of the rabbit, the arrhythmogenic actions of ouabain were studied with microelectrodes. Ouabain (10(-6) M) uniformly produced the following events: (1) a gradual increase in sinus rate with periods of alternation of beta-to-beat atrial intervals, (2) a rapid rate and regular rhythm, (3) severe irregularity of rhythm, (4) total atrial arrest. Cycle length decreased from 394 msec +/- 43 (mean +/- SD) during control to 229 msec +/- 26 during the period of rapid rate and regular rhythm (P less than 0.001). Pretreatment with atropine or propranolol did not abolish this positive chronotropic action of ouabain. Maps of the spread of activation in the area of the sinus node in eight experiments revealed that the speeding up of rate is accompanied by a shift of dominant pacemaker site toward the sinoatrial border. In explanation, it is shown that sinoatrial border fibers develop strong diastolic depolarization, whereas dominant pacemaker fibers do so to a lesser extent or not at all. The atrial arrhythmias--best to be described as "digitalis-induced sinus tachycardia"--may represent the experimental counterpart of the so-called "paroxysmal atrial tachycardia with block" described as a common manifestation of digitalis intoxication in man.

In this study we investigated the response of the isolated rabbit sinus node to ectopic atrial premature beats elicited late in the atrial cycle. In three experiments the response of at least 45 different fibers of the sinus node was recorded, whereas, in other experiments, investigation was less extensive. In this way the spread of activation of the total pacemaker area could be mapped accurately both during spontaneous beating and the induction of ectopic atrial beats of different degrees of prematurity. We found that: (1) The conduction of an impulse from the dominant pacemaker area to the atrium during spontaneous rhythm (antegrade conduction) is slower than the conduction of an ectopic atrial impulse towards the center of the sinus node (retrograde conduction). (2) The action potential of the dominant pacemaker fibers in the sinus node is shortened because of premature activation caused by an ectopic impulse from the atrium. Late premature beats had no effect on diastolic depolarization. If the retrograde activation wave did not reach the area of the dominant pacemaker before the spontaneous discharge of these fibers, there was electrotonic influence demonstrable over a distance of about 0.5 mm. (3) Comparison of the true sinoatrial conduction time with the estimated sinoatrial conduction calculated indirectly from the length of the postextrasystolic atrial cycle revealed that, in the isolated rabbit heart, the calculated value is a serious underestimation of the true antegrade sinoatrial conduction time.

The sinus node is not only important for the generation of the cardiac impulse but also as conductor of this impulse from the site of origin toward the atrium. An easy method to investigate conduction properties of sinus nodal tissue directly is described. The isolated right atrium of the rabbit was divided--via an incision perpendicular to the crista terminalis--into two halves connected only by a bridge of sinus nodal tissue. By means of two atrial surface electrodes conduction through the sinus node bridge was monitored. It appeared that conduction in the sino-atrial border zone is many times slower than in the atrium and refractory period markedly longer. In the center of the sinus node conduction is again slower and refractory period longer than in the border zone. Validity of the method was tested by reconstruction of the conduction route of stimulated impulses using microelectrode recordings. Applications of the method were demonstrated by studying the effects of rate and rhythm, hypothermia, hypoxia, acetylcholine and norepinephrine as well as verapamil. The model is suitable for investigation of the effects of drugs and other interventions on impulse conduction in sinus nodal tissue.

We calculated the wavelength of the atrial impulse in chronically instrumented conscious dogs by measuring both conduction velocity and refractory period: wavelength = refractory period X conduction velocity. Implantation of multiple stimulating and recording electrodes allowed wavelength determination at four different areas: the right and left parts of Bachmann's bundle and the free walls of the right and left atria. During programmed electrical stimulation, three types of arrhythmias were observed: rapid repetitive responses, atrial flutter, and atrial fibrillation. During normal rhythm, the wavelength of the atrial impulse varied between 14 and 18 cm. Premature beats had a shorter wavelength, depending on the degree of prematurity. Premature beats that evoked rapid repetitive responses showed a critical shortening of the wavelength below 12.3 cm. Episodes of atrial flutter were induced at a wavelength below 9.7 cm, while fibrillation occurred at wavelengths shorter than 7.8 cm. We correlated the induction of these arrhythmias with the values of refractory period, conduction velocity, and wavelength during control and during administration of several drugs. Intravenous administration of acetylcholine shortened the wavelength by 30-40%, mainly because of refractory period shortening. Both propafenone and lidocaine had strong but opposite effects on refractoriness and conduction and, consequently, little effect on the wavelength. Quinidine markedly prolonged the refractory period, but prolongation of wavelength was less because of a simultaneous decrease in conduction velocity. d-Sotalol also increased refractory period, but because it had no appreciable effect on conduction velocity, this drug was the most effective in prolongation of wavelength. Linear discriminant analysis of the data showed that the refractory period and the conduction velocity each were poor parameters to predict the occurrence of the different arrhythmias (predictive value 48% and 38%, respectively). The combination of both properties, however, as expressed in the wavelength, was a more reliable index that predicted the induction of the different arrhythmias correctly in 75% of the cases. We conclude that the wavelength is a useful parameter for evaluating antiarrhythmic drugs.

In the isolated blood-perfused canine heart we produced episodes of rapid atrial flutter by continuous infusion of acetylcholine and rapid pacing. The spread of excitation during atrial flutter was mapped with the aid of two endocavitary mapping electrodes containing 960 leads and recording from 192 different sites simultaneously. The flutter maps clearly showed that intra-atrial reentry was the mechanism responsible for the arrhythmia. However, the localization and size of the intra-atrial circuits differed from case to case even in the same heart. The orifices of the venae cavae or the atrioventricular ring did not serve as a central anatomic obstacle for circus movement. We also failed to identify a special role of the internodal pathways in the formation of the loop. Instead, the intra-atrial circuits could be found everywhere, provided sufficient atrial mass was available to accommodate the circuit. The diameter of the circuits varied between 1.5 and 3 cm at a cycle length between 65 and 155 msec. The average conduction velocity of the circulating impulse varied between 60 and 80 cm/sec. Spontaneous termination of atrial flutter frequently occurred and was based on local conduction block in a narrow part of the circuit. Another interesting aspect of these studies is the finding that during continuous circus movement of the impulse, the amount of myocardium that is activated may vary considerably. This marked periodicity in excited tissue mass during atrial flutter could adequately explain the continuously undulating baseline or typical sawtoothlike F waves as seen in the surface electrocardiogram during atrial flutter.