Validation of the Clavien-Madadi Classification for Unexpected Events in Pediatric Surgery: A Collaborative ERNICA Project

BACKGROUND

The Clavien-Madadi classification is a novel instrument for the assessment and grading of unexpected events in pediatric surgery, based on the Clavien-Dindo classification. The system has been adjusted to better fit the pediatric population in a prospective single-center study. There is a need now to validate the Clavien-Madadi classification within an international expert network.

METHODS

A pediatric surgical working group created 19 case scenarios with unexpected events in a multi-staged process. Those were circulated within the European Reference Network of Inherited and Congenital Anomalies (ERNICA) and surgeons were instructed to rate the scenarios according to the Clavien-Madadi vs. Clavien-Dindo classification.

RESULTS

59 surgeons from 12 European countries completed the questionnaire. Based on ratings of the case scenarios, the Clavien-Madadi classification showed significantly superior agreement rates of the respondents (85.9% vs 76.2%; p < 0.05) and was less frequently considered inaccurate for rating the pediatric population compared to Clavien-Dindo (2.1% vs 11.1%; p = 0.05). Fleiss' kappa analysis showed slightly higher strength of agreement using the Clavien-Madadi classification (0.74 vs 0.69). Additionally, intraclass correlation coefficient was slightly higher for the Clavien-Madadi compared to the Clavien-Dindo classification (ICCjust 0.93 vs 0.89; ICCunjust 0.93 vs 0.89). More pediatric surgeons preferred the Clavien-Madadi classification for the case scenarios (43.0% vs 11.8%; p = 0.002) and advantages of the Clavien-Madadi were confirmed by 81.4% of the surgeons.

CONCLUSION

The Clavien-Madadi classification is an accurate and reliable instrument for the grading of unexpected events in pediatric surgery. We therefore recommend its application in clinical and academic pediatric surgical practice.

LEVEL OF EVIDENCE

III.

European reference network for rare inherited congenital anomalies (ERNICA) evidence based guideline on the management of gastroschisis

BACKGROUND

The European Reference Network for rare Inherited Congenital Anomalies, ERNICA, guidelines for gastroschisis cover perinatal period to help teams to improve care.

METHOD

A systematic literature search including 136 publications was conducted. Research findings were assessed following the GRADE methodology. The evidence to decision framework was used to determine the strength and direction of recommendations.

RESULTS

The mode or timing of delivery do not impact neonatal mortality, risk of NEC or time on parenteral nutrition (PN). Intra or extra abdominal bowel dilatation predict complex gastroschisis and longer length of hospital stay but not increased perinatal mortality. Outcomes after Bianchi procedure and primary fascia closure under anesthesia are similar. Sutureless closure decreases the rate of surgical site infections and duration of ventilation compared to surgical closure. Silo-staged closure with or without intubation results in similar outcomes. Outcomes of complex gastroschisis (CG) undergoing early or delayed surgical repair are similar. Early enteral feeds starting within 14 days is associated with lower risk of surgical site infection.

RECOMMENDATIONS

The panel suggests vaginal birth between 37 and 39 w in cases of uncomplicated gastroschisis. Bianchi's approach is an option in simple gastroschisis. Sutureless closure is suggested when general anesthesia can be avoided, sutured closure. If anesthesia is required. Silo treatment without ventilation and general anesthesia can be considered. In CG with atresia primary intestinal repair can be attempted if the condition of patient and intestine allows. Enteral feeds for simple gastroschisis should start within 14 days.

Developing a core outcome set for the health outcomes for children and adults with congenital oesophageal atresia and/or tracheo-oesophageal fistula: OCELOT task group study protocol

INTRODUCTION

Heterogeneity in reported outcomes of infants with oesophageal atresia (OA) with or without tracheo-oesophageal fistula (TOF) prevents effective data pooling. Core outcome sets (COS) have been developed for many conditions to standardise outcome reporting, facilitate meta-analysis and improve the relevance of research for patients and families. Our aim is to develop an internationally-agreed, comprehensive COS for OA-TOF, relevant from birth through to transition and adulthood.

METHODS AND ANALYSIS

A long list of outcomes will be generated using (1) a systematic review of existing studies on OA-TOF and (2) qualitative research with children (patients), adults (patients) and families involving focus groups, semistructured interviews and self-reported outcome activity packs. A two-phase Delphi survey will then be completed by four key stakeholder groups: (1) patients (paediatric and adult); (2) families; (3) healthcare professionals; and (4) researchers. Phase I will include stakeholders individually rating the importance and relevance of each long-listed outcome using a 9-point Likert scale, with the option to suggest additional outcomes not already included. During phase II, stakeholders will review summarised results from phase I relative to their own initial score and then will be asked to rescore the outcome based on this information. Responses from phase II will be summarised using descriptive statistics and a predefined definition of consensus for inclusion or exclusion of outcomes. Following the Delphi process, stakeholder experts will be invited to review data at a consensus meeting and agree on a COS for OA-TOF.

ETHICS AND DISSEMINATION

Ethical approval was sought through the Health Research Authority via the Integrated Research Application System, registration no. 297026. However, approval was deemed not to be required, so study sponsorship and oversight were provided by Alder Hey Children's NHS Foundation Trust. The study has been prospectively registered with the COMET Initiative. The study will be published in an open access forum.

Endoscopic management of esophageal mucosal bridges in children with esophageal atresia

BACKGROUND AND STUDY AIMS

Esophageal mucosal bridge (EMB) may be diagnosed at the anastomotic site in children operated on for esophageal atresia (EA) but so far only a few cases (n = 4) have been reported. This study aimed to characterize EMB in children with EA, risk factors, and treatment.

PATIENTS AND METHODS

This retrospective multicenter study recorded patient's characteristics, EMB diagnosis circumstances, endoscopic management, follow-up, and EMB recurrence in children with EA aged less than 18 years, compared with paired EA patients without EMB.

RESULTS

Thirty patients were included (60% male, 90% EA/tracheoesophageal fistula, 43% associated malformations). Compared to 44 paired controls, EMB was associated with a history of nasogastric tube feeding (31% vs. 9.1%, p = 0.02) and severe gastroesophageal reflux disease (history of fundoplication: 41.4% vs. 13.6%, p < 0.01). 77% had symptoms (food impaction and/or dysphagia). Endoscopic management was performed in 53% of patients (83% electrocoagulation) with no technical difficulties or complications. 80% of the symptomatic patients with EMB improved after endoscopic treatment, independently of anastomotic stricture dilatation or not.

CONCLUSION

EMB endoscopic management by electrocoagulation is safe and often leads to symptom improvement.

Definition, Documentation, and Classification of Complications in Pediatric Surgical Literature-A Plea for Standardization

Severity grading systems for complications in surgical patients have been used since 1992. An increasing assessment of these instruments in pediatric surgery is also noticed, without their validation in children. To analyze the current practice, we performed a literature review with focus on the assessment and grading of complications. The review was performed according to the Preferred Reporting Items for Systematic Reviews and Meta-analyses (PRISMA) guidelines. Studies reporting on postoperative complications as a primary or secondary endpoint using a severity grading system were included. Definition for simple adverse events, classification systems used, and the time horizon of postoperative documentation were analyzed. A total of 566 articles were screened, of which 36 met the inclusion criteria. About 86.1% of the papers were retrospective and 13.9% prospective analyses. None of the studies were prospective-randomized trials. Twenty (55.6%) studies did not include a definition of adverse events, whereas the remaining 16 (44.4%) showed variations in their definitions. All studies applied the Clavien-Dindo classification, whereas five (13.9%) additionally used the Comprehensive Complication Index. One study compared alternative grading instruments with the Clavien-Dindo classification, without demonstrating the superiority of any classification in pediatric surgery. Twenty-two studies (61.1%) did not report the time horizon of perioperative complication documentation, while 8 studies (22.2%) used 30 days and 6 studies (16.7%) used 3 months of postoperative documentation. Definition and classification of postoperative complications are inconsistent in the pediatric surgical literature. Establishment of a standardized protocol is mandatory to accurately compare outcome data.

Variability in the Reporting of Baseline Characteristics, Treatment, and Outcomes in Esophageal Atresia Publications: A Systematic Review

INTRODUCTION

 As survival rates of infants born with esophageal atresia (EA) have improved considerably, research interests are shifting from viability to morbidity and longer-term outcomes. This review aims to identify all parameters studied in recent EA research and determine variability in their reporting, utilization, and definition.

MATERIALS AND METHODS

 Following PRISMA guidelines, we performed a systematic review of literature regarding the main EA care process, published between 2015 and 2021, combining the search term "esophageal atresia" with "morbidity," "mortality," "survival," "outcome," or "complication." Described outcomes were extracted from included publications, along with study and baseline characteristics.

RESULTS

 From 209 publications that met the inclusion criteria, 731 studied parameters were extracted and categorized into patient characteristics (n = 128), treatment and care process characteristics (n = 338), and outcomes (n = 265). Ninety-two of these were reported in more than 5% of included publications. Most frequently reported characteristics were sex (85%), EA type (74%), and repair type (60%). Most frequently reported outcomes were anastomotic stricture (72%), anastomotic leakage (68%), and mortality (66%).

CONCLUSION

 This study demonstrates considerable heterogeneity of studied parameters in EA research, emphasizing the need for standardized reporting to compare results of EA research. Additionally, the identified items may help develop an informed, evidence-based consensus on outcome measurement in esophageal atresia research and standardized data collection in registries or clinical audits, thereby enabling benchmarking and comparing care between centers, regions, and countries.

Growth and Duration of Inflammation Determine Short- and Long-Term Outcome in Very-Low-Birth-Weight Infants Requiring Abdominal Surgery

Necrotizing enterocolitis (NEC), spontaneous intestinal perforation (SIP) and meconium-related ileus (MI) requiring surgical intervention are associated with a high risk of severe short- and long-term complications in very-low-birth-weight (VLBW) infants including poor growth, cholestasis and neurodevelopmental impairment. This retrospective study aimed to identify risk factors for such complications in a cohort of 55 VLBW preterm infants requiring surgery with enterostomy creation due to NEC, SIP or MI. Long-term follow-up was available for 43 (78%) infants. Multiple regression analyses revealed that the duration of inflammation and longitudinal growth determined the risk of cholestasis and neurodevelopmental outcome at 2 years corrected age independent of the aetiology of the intestinal complication. Direct bilirubin increased by 4.9 μmol/L (95%CI 0.26-9.5), 1.4 μmol/L (95%CI 0.6-2.2) and 0.8 μmol/L (95%CI 0.22-1.13) with every day of elevated (Interleukin-6) IL-6, (C-reactive protein) CrP and parenteral nutrition. The mental development index at 2 years corrected age decreased by 3.8 (95%CI -7.3--0.36), 0.4 (95%CI 0.07-0.80) and 0.3 (95%CI 0.08-0.57) with every day of elevated IL-6 and every 1 point decrease in weight percentile at discharge and 2 years. These data stress the importance of optimal timing for the initial surgery in order to prevent prolonged inflammation and an early reversal of the enterostomy in case of poor growth or insufficient enteral nutrition.

Implementation and validation of a novel instrument for the grading of unexpected events in paediatric surgery: Clavien-Madadi classification

BACKGROUND

Inconsistent definitions of complications and unexpected events have limited accurate analysis of surgical outcomes. Perioperative outcome classifications currently used for adult patients have limitations when used for children.

METHODS

A multidisciplinary group of experts modified the Clavien-Dindo classification to increase its utility and accuracy in paediatric surgery cohorts. Organizational and management errors were considered in the novel Clavien-Madadi classification, which focuses on procedural invasiveness rather than anaesthetic management. Unexpected events were prospectively documented in a paediatric surgery cohort. Results of the Clavien-Dindo and Clavien-Madadi classifications were compared and correlated with procedure complexity.

RESULTS

Unexpected events were prospectively documented in a cohort of 17 502 children undergoing surgery between 2017 and 2021. The results of both classifications were highly correlated (ρ = 0.95), although the novel Clavien-Madadi classification identified 449 additional events (organizational and management errors) over the Clavien-Dindo classification, increasing the total number of events by 38 per cent (1605 versus 1158 events). The results of the novel system correlated significantly with the complexity of procedures in children (ρ = 0.756). Furthermore, grading of events > grade III according to the Clavien-Madadi classification showed a higher correlation with procedure complexity (ρ = 0.658) than the Clavien-Dindo classification (ρ = 0.198).

CONCLUSION

The Clavien-Madadi classification is a tool for the detection of surgical and non-medical errors in paediatric surgery populations. Further validation in paediatric surgery populations is required before widespread use.

How Do Young and Old Spontaneously Hypertensive Rats Respond to Antihypertensive Therapy? Comparative Studies on the Effects of Combined Captopril and Nifedipine Treatment

Numerous studies on the effects of antihypertensive treatment in young spontaneously hypertensive rats (SHRs) have shown that early-onset therapy may effectively reduce their blood pressure (BP) even to normotensive values. In contrast, only a few studies investigated the effects of treatment started at an advanced age. These studies revealed that antihypertensive effects are lower in adult or even in senescent SHRs compared with young SHRs. Even more, prevention of cardiac sequelae of hypertension such as hypertrophy and fibrosis is less effective when treatment starts late in life. Because, in patients, combination therapies with calcium antagonists are favored, we studied the efficacy of a combination therapy with captopril and nifedipine in young and old SHRs. We directly compared the treatment effects on BP as well as on cardiac hypertrophy and remodeling between these two animal cohorts. With antihypertensive treatment, significantly lower BP values were achieved in young SHRs despite a shorter treatment period compared with old SHRs. Although treatment effects on cardiac hypertrophy were greater in old than in young SHRs, cardiac fibrosis was significantly attenuated only in young but not in old SHRs. The results emphasize the value of antihypertensive therapy and particularly accentuate the importance of an early-onset therapy. With respect to problems such as late diagnosis and poor therapy adherence, these results may have great importance for the treatment of human hypertension.

Accumulation of Postoperative Unexpected Events Assessed by the Comprehensive Complication Index® as Prognostic Outcome Parameters for Kasai Procedure

Introduction The Kasai procedure in children with biliary atresia (BA) is associated with several complications in the short-term. The Comprehensive Complication Index (CCI®) is a validated metric in adult surgery for the analysis of complications and morbidity in surgical patients. We aimed to analyze the CCI® for the first time in BA infants and to correlate its association with outcomes. Material and Methods We conducted a retrospective review of medical records of infants with type III BA undergoing the Kasai procedure between January 2011 and December 2021 at our institution. All unexpected events were ranked according to the Clavien−Dindo classification, and the CCI® per patient was subsequently calculated. Clavien−Dindo grades, individual events, CCI®, and total event numbers per patient were correlated with one- and two-year outcomes post-surgery. Results A total of 131 events were identified in 101 patients (ranging 0−11 per patient). Forty-four Grade I (33.6%), 67 Grade II (51.1%), 18 Grade III (13.7%), and two sentinel events [>Grade IV] (1.5%) were documented according to Clavien−Dindo, including one death in a cardiac-associated BA patient. None of the complications significantly correlated with a poor outcome. Sixty-three (62.4%) CCI® scores were calculated (range 0−100). The mean CCI® score during the in-patient treatment post-surgery was significantly higher in patients with a poorer outcome than patients with native liver survival at one- and two-year follow-up (22.7 ± 21.7 vs. 13.2 ± 18.1; p = 0.02). Conclusion Not the severity of complications, but the accumulation of numerous events related to Kasai procedure were associated with a poorer outcome. Therefore, the CCI® is an excellent instrument for the postoperative morbidity assessment of BA patients.

Severity grading of unexpected events in paediatric surgery: evaluation of five classification systems and the Comprehensive Complication Index (CCI®)

Background

Postoperative adverse events may be associated with substantial morbidity and mortality. Numerous severity grading systems for these events have been introduced and validated but have not yet been systematically applied in paediatric surgery. This study aimed to analyse the advantages and disadvantages of these classifications in a paediatric cohort.

Methods

Unexpected events associated with interventional or organizational problems in the department of paediatric surgery during 2017–2020 were prospectively documented daily for all children. Events were classified according to the Clavien–Dindo grading system during monthly morbidity and mortality conferences. All events were also classified according to five additional grading systems: T92, contracted Accordion, expanded Accordion, Memorial Sloan Kettering Cancer Center, and Comprehensive Complication Index (CCI)^®.

Results

Of 6296 patients, 673 (10.7 per cent) developed adverse events and 240 (35.7 per cent) had multiple events. Overall, 1253 adverse events were identified; of these, 574 (45.2 per cent) were associated with surgical or medical interventions and 679 (54.8 per cent) included organizational problems. The grading systems demonstrated high overall correlation (r_pears = 0.9), with minor differences in sentinel events. The Clavien–Dindo classification offered the most detailed assessment. However, these details had only limited additional value. The CCI^® scores were correlated with other grading systems (r_pears = 0.9) and were useful in analysing multiple events within individual patients.

Conclusion

Grading systems demonstrated similar scoring patterns for minor and sentinel events, with none being superior for unexpected events in children. However, the CCI^® can be a major improvement in assessing morbidity in patients with multiple events. Its use is therefore recommended in prospective studies on paediatric surgery.

Antihypertensive and cardioprotective effects of different monotherapies and combination therapies in young spontaneously hypertensive rats - A pilot study

Spontaneously hypertensive rats (SHR) are an established animal model for antihypertensive treatment. The aim of this pilot study was a systematic search for two lines of antihypertensive treatment - a monotherapy and a combination of two drugs - to be applied in a future study on old SHR. Originally, representatives of three drug classes recommended for antihypertensive therapy in humans should be applied, namely captopril (CAP) as an antagonist of the renin-angiotensin-aldosterone system, nifedipine (NIF) as calcium channel blocker and propranolol (PROP) as β-adrenergic blocker. As we observed that PROP had been poorly ingested, all groups with PROP therapy were excluded from the study. CAP (60 mg kg^-1 d^-1), NIF (10 mg kg^-1 d^-1) or both were administered orally to seven-week-old SHR over 3 weeks. A further group of SHR received no treatment (SHR/CTRL). Age-matched normotensive Wistar-Kyoto rats served as normotensive controls. We examined the effect of the antihypertensive therapies on systolic blood pressure, heart weight and on histological and biochemical markers of cardiac hypertrophy and fibrosis. CAP proved to be the most effective treatment reducing blood pressure and relative heart weight significantly compared to SHR/CTRL without reaching normotensive values. Beginning cardiac fibrosis observed in SHR/CTRL was completely abrogated with CAP treatment. Similar effects were achieved with a combination of CAP and NIF. CAP as monotherapy and CAP + NIF as combination therapy were chosen for the forthcoming study on old SHR.

Incidence of complications, organizational problems, and errors: Unexpected events in 1605 patients

PURPOSE

Besides surgical complications, a variety of adverse events may affect patients' comfort and outcome. The purpose of this prospective study was to identify the incidence and impact of all unexpected events in pediatric surgical patients.

METHODS

All unexpected events that occurred in our department during the period of February 2017-July 2018 were prospectively assessed. Complications associated with surgery, non-surgical treatment, errors and organizational problems were included. Events were classified using a modified version of Clavien-Dindo. Sentinel events were defined as death, serious injury, or the risk thereof (grade IV-V). Organizational events were analyzed separately. All events were discussed during morbidity and mortality-conferences, and the results and measures were documented.

RESULTS

Unexpected events occurred in 297 of 1605 patients (18.5%), of whom 1124 (70%) had undergone surgery. More than half of all events were not associated with an operation (n=237; 54%). The severity of all events was mostly minor (grade I-IIIb; n=410; 94%). Twenty-eight sentinel events (IV-V) occurred (6% of all events). Twenty-two (2%) patients died; however, none of these deaths were related to surgery. The top 5 events included organizational problems in 78 instants (18%), wound healing disorders in 44 (10%), recurrence of initial problems in 36 (8%), dislocation of indwelling catheters in 26 (6%) and bleeding in 16 (4%). Errors were identified in 15 patients (3%). We derived 10 changes of concepts of management or treatment.

CONCLUSION

The incidence of unexpected events in pediatric surgical patients is high when complications associated with surgical and non-surgical treatment and organizational alterations are documented prospectively. In our study, most events were minor and did not substantially affect patients' outcomes. Prospective assessment helped to identify organizational shortcomings and develop preventive strategies.

Low gestational age is associated with less anastomotic complications after open primary repair of esophageal atresia with tracheoesophageal fistula

BACKGROUND

The aim of this study was to evaluate anastomotic complications after primary one-staged esophageal atresia (EA) repair relating to the patients` gestational age (GA).

METHODS

Retrospective data analyses of patients who underwent closure of tracheoesophageal fistula (TEF) and primary esophageal anastomosis from 01/2007 to 12/2018 in two pediatric surgical centers. Exclusion of EA other than Gross type C, long-gap EA, minimal invasive or staged approach. Postoperative complications during the first year of life were assessed. Associated malformations, the incidence of infant respiratory distress syndrome (IRDS) and intraventricular bleeding were analyzed.

RESULTS

Inclusion of 75 patients who underwent primary EA repair. Low GA was associated with significantly lower incidence of anastomotic complications (p = 0.019, r = 0.596, 95% CI 0.10-0.85). Incidence of anastomotic leakage (0% vs. 5.5%; p = 0.0416), recurrent TEF (0% vs. 5.5%; p = 0.0416) und anastomotic stricture (0% vs. 14.5%; p = 0.0019) was significantly lower in patients < 34 gestational weeks. Incidence of IRDS (55% vs. 0%; p < 0.0001) and intraventricular bleeding (25% vs. 3.6%; p = 0.0299) was significantly higher in patients < 34 gestational weeks.

CONCLUSIONS

Despite prematurity-related morbidity, low GA did not adversely affect surgical outcome after primary EA repair. Low GA was even associated with a better anastomotic outcome indicating feasibility and safety of primary esophageal reconstruction.

[Disease-specific Knowledge in Conservative Treatment of Adolescent Idiopathic Scoliosis]

BACKGROUND

The typical onset of adolescent idiopathic scoliosis falls in a sensitive stage of life. Nevertheless, conservative brace treatment requires a high degree of compliance. Disease-specific knowledge influences therapy outcome in many diseases and potentially improves patient compliance and quality of life. We analysed disease-specific knowledge and quality of life of patients with adolescent idiopathic scoliosis.

METHODS

Scoliosis patients (n = 67) undergoing conservative brace treatment were asked to answer a questionnaire with items about scoliosis-specific knowledge. This was anonymous and prior to regular interviews and examinations. The scoliosis-research-society-22 r score was determined in order to assess quality of life.

RESULTS

The major sources of information for the patients were the attending physicians and the world wide web. The majority stated that they understood the nature of scoliosis, although their answers to more detailed questions revealed a major lack of knowledge. A significant gap in provision of information was found, especially in the field of therapy regimen and treatment goals. The expected duration of the therapy was unclear to most patients. Nevertheless, higher quality of life correlated with high compliance and patients who regarded alleviation of the disturbing appearance of their trunk as a main treatment aim also experienced a lower quality of life in the section of self image.

CONCLUSIONS

Our study revealed a significant lack of disease-specific knowledge in patients with idiopathic scoliosis. Facilitation of knowledge might improve quality of life and therapy outcome in the future. As the attending physicians are the main source of information, it is up to us to improve this situation.

Effects of the atrial antiarrhythmic drug AVE0118 on cardiac ion channels

Previous studies in pigs and goats have demonstrated that AVE0118 prolongs atrial refractoriness without any effect on the QT-interval. The purpose of the present study was to investigate the effect of the compound on various cardiac ion channels. AVE0118 blocked the pig Kv1.5 and the human Kv1.5 expressed in Xenopus oocytes with IC(50) values of 5.4+/-0.7 microM and 6.2+/-0.4 microM respectively. In Chinese hamster ovary (CHO) cells, AVE0118 decreased the steady-state hKv1.5 current with an IC(50) of 1.1+/-0.2 microM. The hKv4.3/KChIP2.2 current in CHO cells was blocked by AVE0118 by accelerating the apparent time-constant of inactivation ( tau(inact)), and the integral current was inhibited with an IC(50) of 3.4+/-0.5 microM. At 10 microM AVE0118 tau(inact) decreased from 9.3+/-0.6 ms ( n=8, control) to 3.0+/-0.3 ms ( n=8). The K(ACh) current was investigated in isolated pig atrial myocytes by application of 10 microM carbachol. At a clamp potential of -100 mV the I(KACh) was half-maximally blocked by 4.5+/-1.6 microM AVE0118. In the absence of carbachol, AVE0118 had no effect on the inward current recorded at -100 mV. Effects on the I(Kr) current were investigated on HERG channels expressed in CHO cells. AVE0118 blocked this current half-maximally at approximately 10 microM. Comparable results were obtained in isolated guinea pig ventricular myocytes, where half-maximal inhibition of the I(Kr) tail current occurred at a similar concentration of AVE0118. Other ionic currents, like the I(Ks), I(KATP) (recorded in guinea pig ventricular myocytes), and L-type Ca(2+) (recorded in pig atrial myocytes) were blocked by 10 microM AVE0118 by 10+/-3% ( n=6), 28+/-7% ( n=4), and 22+/-13% ( n=5) respectively. In summary, AVE0118 preferentially inhibits the atrial K(+) channels I(Kur), I(to) and I(KACH). This profile may explain the selective prolongation of atrial refractoriness described previously in pigs and goats.

Synthesis and activity of novel and selective I(Ks)-channel blockers

Since the discovery of the I(Ks)-potassium channel as the slowly activating component of the delayed rectifier current (I(k)) in cardiac tissue, the search for blockers of this current has been intense. During the screening of K(ATP)-channel openers of the chromanol type we found that chromanol 293B was able to block I(Ks). Chromanol 293B is a sulfonamide analogue of the K(ATP)-channel openers but had no activity on this target. Experiments were initiated to improve the activity and properties based on this lead compound. As a screening model we used Xenopus oocytes injected with human minK (KCNE1). Variations of the aromatic substituent and the sulfonamide group were prepared, and their activity was evaluated. We found that the greatest influence on activity was found in the aromatic substituents. The most active compounds were alkoxy substituted. We chose HMR1556 ((3R, 4S)-(+)-N-[-3-hydroxy-2,2-dimethyl-6-(4,4,4-trifluorobutoxy)chroman-4-yl]-N-methyl-ethanesulfonamide) 10a for development as an antiarrhythmic drug. The absolute configuration, resulting from an X-ray single-crystal structure analysis, was determined.

Characterization of a novel Kv1.5 channel blocker in Xenopus oocytes, CHO cells, human and rat cardiomyocytes

The inhibitory effects of the novel Kv1.5 channel blocker, S9947 (2'-(benzyloxycarbonylaminomethyl)biphenyl-2-carboxylic acid 2-(2-pyridyl)ethylamide), on cloned human Kv1.5 (hKv1.5), expressed in both Xenopus oocytes and Chinese hamster ovary (CHO) cells, and on native cardiac ultrarapid delayed rectifier potassium currents (IKur) in rat (ventricle myocytes) and human (atrial myocytes) were investigated. The influence of S9947 on the action potential was examined in rat ventricular myocytes. Using the two-electrode voltage-clamp technique in Xenopus oocytes and the patch-clamp technique (whole cell configuration) in CHO cells, hKv1.5 was inhibited by S9947 with IC50 values of 0.65 microM and 0.42 microM, respectively. In addition, inhibition of human Kv4.3 (hKv4.3) and HERG by 10 microM S9947 was low (approximately 20%) and absent, respectively. Using the patch-clamp technique in the whole cell configuration, IKur currents in rat ventricular (rIKur) cardiomyocytes and human atrial (hIKur) cardiomyocytes were inhibited by S9947 with IC50 values of 0.96 microM and 0.07 microM, respectively. In contrast, rat cardiac inward rectifier current (rIK1) and rat (rIto) and human (hIto) cardiac transient outward currents were only inhibited by approximately 20% with 10 microM S9947. In rat cardiomyocytes, using the patch-clamp technique, action potential duration was increased by S9947 in a concentration-dependent (0.3-10 microM) and rate-independent manner. The data show that S9947 suppresses both cloned (Kv1.5) and native (IKur) cardiac potassium currents. Furthermore, S9947 prolongs rat action potential in a rate-independent manner.

Inhibition of IKs channels by HMR 1556

Chromanol HMR 1556 [(3R,4S)-(+)-N-[3-hydroxy-2,2-dimethyl-6-(4,4,4-trifluorobutoxy)chroman-4-yl]-N-methylmethanesulfonamide], a novel inhibitor of the slow component of the delayed outward current in heart muscle cells (IKs), has been characterized in several in-vitro systems. mRNA encoding for the human protein minK was injected into Xenopus oocytes, leading to the expression of IKs channels. HMR 1556 inhibited this current half-maximally at a concentration of 120 nmol/l (IC50). Expression of the K+ channels Herg, Kv 1.5, Kv 1.3 and Kir2.1, and also the cationic current HCN2, were blocked little or not at all by 10 micromol/l HMR 1556. In isolated ventricular myocytes from the guinea pig the whole-cell patch-clamp method revealed inhibition of the IKs current with an IC50, of 34 nmol/l. Other current components, like IKr and IK1. were only slightly blocked at an HMR 1556 concentration of 10 micromol/l, whereas 10 micromol/l HMR 1556 inhibited the transient outward current I(to) and the sustained outward current I(sus) in rat ventricular myocytes by 25% and 36%, respectively. The L-type Ca2+ channel in guinea pig cardiomyocytes was blocked by 10 micromol/l HMR 1556 by 31%. Guinea pig right papillary muscles were investigated by the micropuncture technique at various pacing rates. In the frequency range of 0.5-7 Hz HMR 1556 (1 micromol/l) caused a prolongation of the action potential duration at 90% repolarization (APD90) by 19%-27%. In the presence of isoproterenol (10 micromol/l) the prolongation of the APD90 was more pronounced at low pacing rates (47% at 0.5 Hz and 35% at 1 Hz, compared with 25% at 7 Hz). The monophasic action potential was recorded in Langendorff-perfused guinea pig hearts. In spontaneously beating preparations, HMR 1556, at 0.1 micromol/l and 1 micromol/l, prolonged the MAPD90 by 3% and 10%, respectively, with no further prolongation at 10 micromol/l. The prolongation was much greater at low pacing rates [25% at 100 beats per min (bpm) and 13% at 150 bpm] than at fast pacing rates (9% at 350 bpm). The left ventricular pressure LVPmax was not affected at 1 micromol/l HMR 1556, but it decreased by 15% at 10 micromol/l. Other parameters, like the heart rate and coronary flow, were only slightly decreased at 1 micromol/l HMR 1556. In conclusion, HMR 1556 is a potent and selective inhibitor of the IKs current in guinea pig ventricular myocytes. The prolongation of the action potential duration is maintained at fast pacing rates.

Molecular impact of MinK on the enantiospecific block of I(Ks) by chromanols

Slowly activating I:(Ks) (KCNQ1/MinK) channels were expressed in Xenopous: oocytes and their sensitivity to chromanols was compared to homomeric KCNQ1 channels. To elucidate the contribution of the ss-subunit MinK on chromanol block, a formerly described chromanol HMR 1556 and its enantiomer S5557 were tested for enantio-specificity in blocking I:(Ks) and KCNQ1 as shown for the single enantiomers of chromanol 293B. Both enantiomers blocked homomeric KCNQ1 channels to a lesser extent than heteromeric I:(Ks) channels. Furthermore, we expressed both WT and mutant MinK subunits to examine the involvement of particular MinK protein regions in channel block by chromanols. Through a broad variety of MinK deletion and point mutants, we could not identify amino acids or regions where sensitivity was abolished or strikingly diminished (>2.5 fold). This could indicate that MinK does not directly take part in chromanol binding but acts allosterically to facilitate drug binding to the principal subunit KCNQ1.

Quantum cryptography using entangled photons in energy-time bell states

We present a setup for quantum cryptography based on photon pairs in energy-time Bell states and show its feasibility in a laboratory experiment. Our scheme combines the advantages of using photon pairs instead of faint laser pulses and the possibility to preserve energy-time entanglement over long distances. Moreover, using four-dimensional energy-time states, no fast random change of bases is required in our setup: Nature itself decides whether to measure in the energy or in the time base, thus rendering eavesdropper attacks based on "photon number splitting" less efficient.

Cardiovascular actions of the furoxan CAS 1609, a novel nitric oxide donor

1. This study examines the cardiovascular effects of CAS 1609 (4-hydroxymethyl-furoxan-3-carboxamide) in vitro as well as in vivo in various animal models. 2. CAS 1609 relaxed guinea-pig pulmonary artery strips without endothelium with IC50-values of 0.9 microM (phenylephrine contracted) and 15 microM (KCl-depolarized). This effect was inhibited by oxyhaemoglobin. In these arteries CAS 1609 significantly increased (+192%) guanosine 3':5'-cyclic monophosphate levels, which indicates that the compound acts as a donor of nitric oxide (NO). 3. In the anaesthetized pig, CAS 1609 (0.3-1.0 mg kg-1, i.d.) significantly lowered blood pressure and left ventricular end-diastolic pressure. Left ventricular contractility was slightly reduced and heart rate remained almost unchanged. 4. In anaesthetized dogs, i.v. or i.d. administration of CAS 1609 (0.3-3.0 mg kg-1) decreased, in a dose-related fashion, preload and afterload of the heart, cardiac output, left ventricular work and myocardial oxygen consumption. This haemodynamic profile is similar to that of known NO-donors. 5. In anaesthetized dogs with acute heart failure due to intracoronary injection of microspheres, CAS 1609 (0.3 mg kg-1, i.v.) improved the haemodynamic condition and reduced mortality by 80%. 6. In conscious dogs, oral treatment with a dose of 0.5 mg kg-1 given twice daily at 07 h 00 min and 19 h 00 min (each dose had a duration of action > or = 12 h) for 5 days showed no signs of tolerance to the haemodynamic effects of the drug. 7. All these data indicate that CAS 1609 is a potent, long-lasting orally active donor of NO, devoid of tolerance development.

Studies of desensitization and cross-desensitization to immunologic and nonimmunologic stimuli that evoke contraction and histamine release in superfused guinea pig trachea

This study examined the possibility that there is cross-desensitization between immunologic and nonimmunologic stimuli that evoke contraction and histamine release (HR) in the isolated guinea pig trachea. Compound 48/80 and D-tubocurarine were found to cause homologous and heterologous desensitization for both contraction and HR from superfused trachea. Specific antigen challenge of trachea obtained from animals sensitized with either IgG1 (ovalbumin [OA]) or IgE (oxazalone-human serum albumin [OX-HSA]) also resulted in homologous desensitization for both contraction and HR. However, in experiments with animals sensitized with both IgG1 and IgE antibodies, prechallenge with OA resulted in cross-desensitization to OX-HSA, whereas the reverse sequence was ineffective in eliciting this phenomenon. This may be related to the type of desensitization produced by each antigen (specific versus nonspecific) or to heterogeneity of mast cells in the tissue. Prechallenge of the trachea with compound 48/80 or D-tubocurarine failed to alter subsequent effects of antigen after active sensitization with OA or passive sensitization with either IgG1 or IgE antibodies. Small but statistically significant decreases in tracheal responses to D-tubocurarine were observed after antigen prechallenge to active both IgG1 and IgE antibodies. This is the first study to demonstrate a cross-desensitization between compound 48/80 and D-tubocurarine and the first to examine cross-desensitization with IgG1 and IgE antibodies in the guinea pig trachea. The overall conclusion is that there is no major overlap in the desensitization mechanisms between immunologic and nonimmunologic stimuli in the guinea pig trachea.

Isolation of guinea pig basophils using anti-leukocyte antibody and density gradient centrifugation on Percoll

Peripheral blood basophils were isolated from guinea pigs using a 2-step procedure. Initial enrichment of basophils was achieved by treating leukocyte preparations obtained from whole blood with antibody to contaminating granulocytes and mononuclear cells. Basophil populations of 82% purity (mean; range 65-99%) were obtained by subsequent application of the antibody treated preparation to discontinuous Percoll gradients. The isolated basophils were viable and shown to be functional by histamine release upon stimulation with various secretogogues.