Reversal Procedure Research Articles

Effect of diethylstilbestrol (DES) and 17 β-estradiol (E2) on growth, survival and histological structure of the internal organs in juvenile European catfish Silurus glanis (L.)

The effect of supplemented commercial diets with diethylstilbestrol (DES—15, 30 and 60 mg kg−1) and 17 β-estradiol (E2—30 and 60 mg kg−1), two chemicals commonly used in sex reversal procedure in fish, on survival and growth parameters of juvenile European catfish (Silurus glanis) was evaluated. During the two experiments, lasting 28 days each, fish were kept at temperature 25.2–26.5 °C, pH 7.4–9.3 and oxygen concentration 5.0–7.3 mg O2 dm−3. DES supplementation resulted in depressed growth rate of catfish. In experimental groups fed with E2, no negative effect on growth parameters was found. Both chemicals did not result in observed mortality. In all of the experimental DES groups, hepatosomatic index increased significantly, which suggests negative influence on physiological condition of catfish. DES supplementation significantly changed cytological factors of liver cells and caused hepatic alterations in parenchyma, such as vacuolization and blood congestion. Similarly, supplementation of E2 in food resulted in changes in cytological parameters of hepatocytes. However, E2 did not cause pathological changes within the liver tissue. Histological examination of the catfish gonads showed 19 and 38 % of sterile fish after treatment with 30 and 60 mg kg−1 of DES, respectively. The results suggest that DES served in food could be ineffective in hormonal feminization process of European catfish. No disturbances of sex differentiation process after E2 treatment were observed. However, slight feminization effect in the highest level of E2 treatment group was recorded.

Localization of aeroacoustic sound sources in viscous flows by a time reversal method

A time reversal procedure used previously for aeroacoustic source localization is extended to the viscous flows case. Successive flow configurations including steady flows and unsteady ones have been performed to test and validate the proposed procedure. It is demonstrated that it provides a useful methodology for the detection and the localization of aeroacoustic sources, not only in presence of a dissipative medium but also in unsteady flow configurations. When dealing with dissipative media, the application of time-reversal procedure allows for the recovery of both the shape and the location of the source of sound even if the source amplitude is damped due to the viscous energy loss. For unsteady flows (in presence or not of a dissipative medium), the aeroacoustic source detection method remains always effective even if some theoretical assumptions are not fully satisfied.

Prediction and surprise in human fear conditioning (Commentary on Boll et al.)

The amygdala has long been recognized as crucial for the processing of emotional information, especially fear and negative affect. In this article (Boll et al., 2012), the authors approach amygdala function in human fear conditioning with considerable subtlety. Using high-resolution functional magnetic resonance imaging, they track the updating of processing of both cues and outcomes as participants’ expectancies are first confirmed and then violated. Going beyond other recent investigations (Li et al., 2011), the authors identify subregion-specific amygdala blood oxygen level-dependent responses that separately reflect outcome prediction and prediction error signals. Pavlovian fear conditioning, in which initially meaningless conditioned stimuli (CSs) paired with noxious unconditioned stimuli (USs) acquire the ability to elicit fear, has served as a primary model for studying the neurobiological basis of learning. Much of the research generated by that model has been based on variants of the dictum of Hebb (1949), often paraphrased as ‘systems of cells that fire together, wire together’. The amygdala quickly emerged as a site at which CS and US information converged, and hence could be ‘wired together’ when CSs and USs occurred contiguously in time. However, CS–US contiguity alone is insufficient for associative learning to occur. For example, if a US is already well predicted on the basis of one CS, pairings of a compound of that CS and a new CS with the US often result in little evidence for learning about the new CS, a phenomenon known as ‘blocking’. To deal with many such observations, most learning theories of the past 40 years incorporate the idea that new learning depends critically on prediction error, the difference between expected and received outcomes. Within these models, the importance of CS–US contiguity in the establishment of associations is reaffirmed, but processing of either the CS, the US, or both, is modulated by prediction error, such that unexpected USs or the CSs that precede them (or both) are processed better than expected USs or their accompanying CSs. Considerable evidence from reward conditioning procedures supports the view that the processing of both CSs and USs is indeed modulated by prediction error, and has indicated a number of brain substrates for this modulation, including midbrain dopamine neurons and the amygdala (Holland & Maddux, 2010). In this study, participants were exposed to a discrimination reversal procedure, in which initially one CS was paired with shock and another CS was not, and later the roles of the two stimuli were reversed. Although a ‘US processing’ model, in which prediction error modulates US effectiveness, fit participants’ ratings of shock expectancy better than a random model, a ‘hybrid’ model that included effects of prediction error on both CS and US processing fared best. The authors examined the amygdala and midbrain blood oxygen level-dependent correlates of CS-induced predictions of shock and its absence, and of the prediction errors induced by the surprising omission or presentation of the shock, when the discrimination was reversed, fitted to the hybrid model. Correlates of unsigned prediction error when the US was unexpectedly presented or omitted were observed in both centromedial amygdala and substantia nigra/ventral tegmental areas, whereas the basolateral amygdala blood oxygen level-dependent response during the CSs was negatively correlated with subsequent prediction error, and hence was related to prediction accuracy. The work nicely demonstrates convergence of human and animal research concerning fundamental issues of learning in the questions posed (what are the consequences of the confirmation and violation of learned expectancies for information processing), the approaches taken (quantitative modeling based on well-documented theories of learning), and the behavioral and neural processing results obtained, despite differences in species, behavioral measures, and measures of brain activity. The use of common approaches and theoretical perspectives across human and animal studies, each with their own strengths and shortcomings, may provide a unified approach to understanding relations between cognitive and affective processing.

Minimally invasive versus open surgery for reversal of tubal sterilization.

Although tubal sterilization procedures are considered to be permanent, requests for reversal of the procedure (re-canalisation) are not infrequent. The reversal procedure can be done either by an open laparotomy or by minimally invasive surgery (laparoscopic or robotic approach). To compare the relative effectiveness and safety of reversal of tubal sterilization by open laparotomy, laparoscopy and robotically assisted endoscopy. On 23 October 2012 we searched the Cochrane Menstrual Disorders and Subfertility Review Group Specialised Register; the Cochrane Central Register of Controlled Trials (CENTRAL) in The Cochrane Library (Issue 10, 2012); MEDLINE; EMBASE; LILACS; clinical trials registries; regional databases; conference proceedings; and references for relevant published, unpublished and ongoing trials. Randomised trials comparing the different methods of surgical reversal of tubal sterilisation. No trials that met the selection criteria were identified. No data for evaluation were obtained Currently there is no evidence from randomised controlled trials to recommend or refute the use of a minimally invasive surgical approach (laparoscopic or robotic) or open surgery for reversal of tubal sterilization. There is a need for well conducted and reported randomised clinical trials to generate reliable evidence to inform clinical practice.

Surgical Access Through the Stoma for Laparoscopic Reversal of Hartmann Procedures

The rate of stoma reversal after Hartmann procedure is low, principally because of the technically demanding nature of the reversal procedure and preexisting comorbid disease frequently present in this patient group. Laparoscopic reversal of Hartmann procedure is an attractive alternative that can reduce perioperative morbidity but the feasibility of completing the procedure laparoscopically is often limited by extensive adhesion formation present after the initial open operation. We describe a technique for laparoscopic reversal of Hartmann procedure where the stoma is mobilized externally and a pneumoperitoneum established through this preexisting defect. Results for the first 7 cases show a median operative duration of 132 minutes and length of hospital stay of 6 days with no conversions. Insertion of the operating ports under direct vision and a more limited dissection to facilitate the anastomosis represents an alternative operative strategy that can be performed successfully, even in patients with comorbid disease.

Total Laparoscopic Reversal of Hartmann's Procedure

Hartmann's procedure is still performed in those cases in which colorectal anastomosis might be unsafe. Reversal of Hartmann's procedure (HR) is considered a major surgical procedure with a high morbidity (55 to 60%) and mortality rate (0 to 4%). To decrease these rates, laparoscopic Hartmann's reversal procedure was successfully experienced. We report our totally laparoscopic Hartmann's reversal technique. Between 2004 and 2010 we performed 27 HRs with a totally laparoscopic approach. The efficacy and safety of this technique were demonstrated evaluating the operative data, postoperative complications, and the outcome of the patients. There were no open conversions or major intraoperative complications. Anastomotic leaking occurred in one patient requiring an ileostomy; one patient needed a blood transfusion and one had a nosocomial pneumonia. The mean postoperative hospitalization was 5.7 days. Laparoscopic HR is a feasible and safe procedure and can be considered a valid alternative to open HR.

Alterations in Left Ventricular Preload Dynamically Regulate Cardiac Fibroblast Signaling

Left ventricular (LV) hemodynamic volume overload (VO) inhibits cardiac fibrosis in vivo. However, the effects of hemodynamic load changes on connective tissue growth factor (CTGF) and TGF‐β1induced extracellular matrix (ECM) proteins are poorly understood. This study investigated the impact of load‐driven changes on cardiac fibroblast (CF) phenotype and signaling.MethodsSprague‐Dawley rats underwent sham/aortocaval fistula (ACF) surgery to induce VO heart failure for 4 weeks (compensatory stage), followed by a load reversal procedure in a subset of rats. Primary cultured LV CFs were obtained at 5 day post VO reversal, and ECM signaling molecules were studied by protein and gene expression profiling.ResultsCollagen 1 secretion was decreased in both ACF and reversal CFs, while CTGF mRNA expression decreased only in ACF CFs, consistent with an anti‐fibrotic phenotype. Interestingly, ACF and reversal CFs demonstrated increased TGF‐β1 mRNA expression and similar Smad activation in response to exogenous TGF‐ β1. However, β1‐integrin expression and downstream AKT signaling was suppressed in ACF CFs compared to sham, but normalized following VO reversal.ConclusionThese data suggest that hemodynamic load modulates CF signaling and secretion of ECM proteins. Molecular profiling is necessary to understand how LV hemodynamic changes impact CF‐dependent ECM regulation.

1995 THE NEED FOR EPIDIDYMOVASOSTOMY AT VASECTOMY REVERSAL PLATEAUS IN OLDER VASECTOMIES

INTRODUCTION AND OBJECTIVES: Most vasectomy reversals require vasovasostomy (VV) for successful repair. However, as the obstructive interval after vasectomy lengthens, so does the rate of epididymal obstruction and the need for epididymovasostomy (EV). Since spermatid counts are lower in testes with chronic obstruction after vasectomy (Jarow et al, NEJM, 1985), we hypothesized that decreased sperm production associated with older vasectomy age could protect the system from epididymal blowout. With this in mind, we sought to better define how the need for EV changes with obstructive interval after vasectomy. METHODS: In a retrospective review of consecutive vasectomy reversals performed by a single surgeon, the relationship between the type of reversal procedure was correlated with age of vasectomy and the age of the patient. An EV was performed in the presence of occasional sperm fragments with creamy fluid (Silber score 4 fluid) or complete vasospermia (Silber score 5). RESULTS: Among 165 patients who underwent reversal and who had adequate follow-up, 65 men had either unilateral (n 39) or bilateral EV’s (n 29) for an overall rate of 40% (65/165) of reversals. Among all cases, the mean patient age was 44 / 7 years. Median vasectomy age was 10 years (range 1 to 37). The rate of needing either unilateral (EV/VV) or bilateral EV increased linearly over vasectomy ages 1-21 years, but plateaus off (combined rate between 56%-75% of cases) from vasectomy ages 22-37 years (Figure). CONCLUSIONS: Although the rate of needing either unilateral or bilateral EV at vasectomy reversal increases with vasectomy age, this relationship does not remain linear throughout all vasectomy ages. The rate of EV actually plateaus after 22 years of vasectomy, suggesting that downregulated sperm production or sufficient storage capacity exists to protect some older vasectomies from “blowout.”

Needlescopic video-assisted thoracic surgery for reversal of thoracic sympathectomy

Thoracic sympathectomy is a commonly performed surgical procedure for the treatment of palmar hyperhidrosis. However, one major complication of such a procedure is compensatory truncal hyperhidrosis. We describe an extreme case of compensatory truncal hyperhidrosis and anhidrosis over the head and neck region which led to a heatstroke. Bilateral reoperative needlescopic video-assisted thoracic surgery was performed for the reversal of thoracic sympathectomy with an interposition intercostal nerve graft. The patient's truncal hyperhidrosis resolved gradually over 1 month following the reversal procedure.

Rapid changes in genes regulating cardiac remodeling following reversal of LV volume overload

Molecular changes involved in cardiac remodeling following reversal of volume overload are relatively unknown. This study evaluated the expression of genes known to regulate cardiac remodeling following acute reversal of volume overload-induced heart failure. Methods Sprague-Dawley rats underwent sham/aortocaval fistula (ACF) surgery to induce volume overload heart failure for 4 wks (compensatory stage), followed by a reversal procedure in a subset of sham and ACF rats. Left ventricular (LV) structure and function were studied at 2–5d post-reversal by echocardiography while gene expression profiling was studied by qRT-PCR. Results At 5d post-reversal, increased LV end-diastolic dimension in ACF was normalized. Fractional shortening was reduced both in ACF and ACF+Rev compared to that of sham. Increased gene expression of proteins involved in extracellular matrix remodeling (collagen1a1, collagen3a1, elastin, periostin, TIMP-1 and TIMP-2) in ACF was normalized by reversal. On the other hand, hypertrophic marker β-myosin heavy chain was elevated by reversal compared to sham and ACF, while the expression of genes involved in excitation contraction coupling (b1-Adrenergic receptor and SERCA2) were decreased in ACF. Conclusion These results reveal multiple gene changes following hemodynamic reversal, suggesting a role in reverse LV structural and functional remodeling.

Impact detection in anisotropic materials using a time reversal approach

This article presents an in situ imaging method able to detect in real-time the impact source location in reverberant complex composite structures using only one passive sensor. This technique is based on the time reversal acoustic method applied to a number of waveforms stored in a database containing the impulse response (Green’s function) of the structure. The proposed method allows achieving the optimal focalization of the acoustic emission source in the time and spatial domain as it overcomes the drawbacks of other ultrasonic techniques. This is mainly due to the dispersive nature of guided Lamb waves as well as the presence of multiple scattering and mode conversion that can degrade the quality of the focusing, causing poor localization. Conversely, using the benefits of a diffuse wave field, the imaging of the source location can be obtained through a virtual time reversal procedure, which does not require any iterative algorithms and a priori knowledge of the mechanical properties and the anisotropic group speed. The efficiency of this method is experimentally demonstrated on a stiffened composite panel. The results showed that the impact source location can be retrieved with a high level of accuracy in any position of the structure (maximum error was less than 3%).

Efectos del reforzamiento de respuestas fragmentarias en el "uso" del género del artículo en niños preescolares.

The correct “usa ge” of thc article’s gen áer in pAirases was experimentally studiecl on three preschool chilclren. The operant level of lhe grammatical particle was recorded in dic absence of either prompting or reinforccment. The experimental treatment invulvcd reinforcing the association of those frag­mentar» responses which were cornponents of both the article and the noun. .4 reversal procedure was used lo evaiuate the experimental effects. Results showed an increase from zero tu one hstndreá percent in performance from baseline to the experimental treatment. Results are analyzed in terms of the acquisition of extended idiomatic segments, instead of tite analysis implied by traditional molecular hypotheses which postulate pro found or behavioral generative processes.

Reversing entanglement change by a weak measurement

Entanglement of a system changes due to interactions with the environment. A typical type of interaction is amplitude damping. If we add a detector to monitor the environment and only select the no-damping outcome, this amplitude damping is modified into a weak measurement. Here we show that the entanglement change of a two-qubit state due to amplitude damping or weak measurement can be probabilistically reversed. For the amplitude-damping case, the entanglement partially recovers under most conditions. For the weak-measurement case, the recovery of the initial entangled state is exact. The reversal procedure involves another weak measurement, preceded and followed by bit flips applied to both qubits. We propose a linear optics scheme for the experimental demonstration of these procedures.

Intervenção Analítico-Comportamental em Tricotilomania.

O presente estudo objetivou analisar funcionalmente o comportamento-problema de puxar os fios de cabelo de uma pessoa diagnosticada com tricotilomania, por meio do procedimento de reversão do hábito. A participante era uma jovem solteira de 21 anos, estudante universitária e encontravase em tratamento médico e farmacológico desde os 12 anos de idade. Para demonstrar o controle experimental dos procedimentos, foi utilizado o delineamento de Reversão-Replicação no formato ABAB, seguido por follow-up. O programa de intervenção foi efetivo na redução do comportamento de arrancar os fios de cabelos, que se manteve no follow-up.

Decoherence suppression by quantum measurement reversal

We show that qubit decoherence due to zero-temperature energy relaxation can be almost completely suppressed by using the quantum uncollapsing (measurement reversal) procedure. To protect a qubit state, a partial quantum measurement moves it toward the ground state, where it is kept during the storage period, while the second partial measurement restores the initial state. This procedure preferentially selects the cases without energy decay events. Stronger decoherence suppression requires smaller selection probability; a desired point in this trade-off can be chosen by varying the measurement strength. The experiment can be realized in a straightforward way using the superconducting phase qubit.

ASSESSMENT OF THE RELATIVE EFFECTS OF ATTENTION AND ESCAPE ON NONCOMPLIANCE

The current study presents a method for assessing the relative effects of attention and escape on noncompliance in preschoolers. Attention and escape conditions were alternated in a multielement design, and a contingency reversal procedure, in which one test condition served as a control for the other, was used to demonstrate control. For all 3 participants, noncompliance was maintained, at least in part, by social attention. Functional analyses of noncompliance such as the one described here may be valuable for developing function-based treatments.

Treatment of idiopathic toe-walking in children with autism using GaitSpot Auditory Speakers and simplified habit reversal

This study aimed to examine the effectiveness of a simplified habit reversal procedure (SHR) using differential reinforcement of incompatible behaviour (DRI) and a stimulus prompt (GaitSpot Auditory Squeakers) to reduce the frequency of idiopathic toe-walking (ITW) and increase the frequency of correct heel-to-toe-walking in three children with autism. The study involved a delayed multiple baseline changing criterion design across individuals. Firstly, a baseline phase was conducted to determine the number of intervals where ITW occurred. Secondly, the GaitSpot Auditory Squeakers were paired with reinforcers. Thirdly, children wore GaitSpot squeakers over the heels of their feet under their shoes for a small number of 10 min sessions and when weight was placed on their heel, a squeak was emitted which was subsequently reinforced. Fourthly, the length of time the children wore the GaitSpot Auditory Squeakers was extended. Finally, the GaitSpot Auditory Squeakers were faded out and tests for generalisation and maintenance of heel-to-toe walking were conducted. The intervention produced substantial reductions in ITW across all participants though degree of reduction differed. The role of SHR and additional modifications for the treatment of ITW are discussed.

Thoracoscopic sympathetic clipping for hyperhidrosis: Long-term results and reversibility

The study objectives were to assess 1) postoperative satisfaction and the occurrence of compensatory sweating after endoscopic thoracic sympathetic clipping in a consecutive series of patients and 2) the reversibility of adverse effects by removing the surgical clips. Between June 1998 and March 2006, 727 patients undergoing bilateral endoscopic thoracic sympathetic clipping for hyperhidrosis or facial blushing were prospectively followed for postoperative satisfaction and subjective compensatory sweating. The effect of removing the surgical clips was assessed in 34 patients who underwent a subsequent reversal procedure after endoscopic thoracic sympathetic clipping. Satisfaction and compensatory sweating were assessed using a visual analogue scale ranging from 0 to 10, with 10 indicating the highest degree. Follow-up was complete in 666 patients (92%). The median age was 26.9 years, and 383 (53%) were men. The level of sympathetic clipping was T2 in 399 patients (55%), T2+3 in 55 patients (8%), and T3+4 in 273 patients (38%). Median follow-up was 10.4 months (range 0-83 months). Excellent satisfaction (8-10 on visual analogue scale) was seen at last follow-up in 288 (74%) of the T2 group, 33 (62%) of the T2+3 group, and 184 (85%) of the T3+4 group. Postoperative satisfaction was significantly higher in the T3+4 group when compared with the T2 or T2+3 groups (P < .01). Severe compensatory sweating (8-10 on the visual analogue scale) was reported in 42 (13%) of the T2 group, 11 (28%) of the T2+3 group, and 17 (8%) of the T3+4 group. Postoperative compensatory sweating was significantly lower in the T3+4 group when compared with the T2 or T2+3 groups (P < .05). Thirty-four patients have subsequently undergone removal of the surgical clips after endoscopic thoracic sympathetic clipping. Follow-up was complete in 31 patients. The reasons for removal included severe compensatory sweating in 32 patients, anhydrosis of the upper limb in 4 patients, lack of improvement or recurrence of hyperhidrosis in 5 patients, and other adverse symptoms in 5 patients. The reversal procedure was done after a median time of 11.0 months (range 1-57 months) after endoscopic thoracic sympathetic clipping. The initial level of clipping was T2 in 21 patients, T2+3 in 7 patients, and T3+4 in 6 patients. There was a trend toward fewer subsequent reversal procedures in the T3+4 group when compared with the T2 or T2+3 groups (P = .06). Fifteen patients (48%) reported a substantial decrease in their compensatory sweating (5-10 on the visual analogue scale) after reversal. Thirteen patients (42%) reported that their initial hyperhidrosis or facial blushing has remained well controlled (8-10 on the visual analogue scale) after reversal. There was no significant relationship between the original level of clipping and the interval between endoscopic thoracic sympathetic clipping and the subsequent reversal and reversibility of symptoms. When compared with endoscopic thoracic sympathetic clipping at the T2 or T2+3 levels, endoscopic thoracic sympathetic clipping at the T3+4 level was associated with a higher satisfaction rate, a lower rate of severe compensatory sweating, and a trend toward fewer subsequent reversal procedures. Subjective reversibility of adverse effects after endoscopic thoracic sympathetic clipping was seen in approximately half of the patients who underwent endoscopic removal of surgical clips. Although yet to be supported by electrophysiologic studies, reversal of sympathetic clipping seems to provide acceptable results and should be considered in selected patients.

Dramatically Decreased Cocaine Self-Administration in Dopamine But Not Serotonin Transporter Knock-Out Mice

There has been much interest in the relative importance of dopamine and serotonin transporters in the abuse-related-effects of cocaine. We tested the hypotheses that mice lacking the dopamine transporter (DAT(-/-)), the serotonin transporter (SERT(-/-)), or both (DAT(-/-)SERT(-/-)) exhibit decreased reinforcing effects of cocaine. We also assessed whether observed effects on self-administration are specific to cocaine or if operant behavior maintained by food or a direct dopamine agonist are similarly affected. We used a broad range of experimental conditions that included acquisition without previous training, behavior established with food training and subsequent testing with food, cocaine or a direct dopamine agonist as reinforcers, fixed ratio and progressive ratio schedules of reinforcement, and a reversal procedure. Wild-type mice readily acquired cocaine self-administration and showed dose-response curves characteristic of the schedule of reinforcement that was used. While some DAT(-/-) mice appeared to acquire cocaine self-administration transiently, almost all DAT(-/-) mice failed to self-administer cocaine reliably. Food-maintained behaviors were not decreased by the DAT mutation, and IV self-administration of a direct dopamine agonist was robust in the DAT(-/-) mice. In contrast to those mice, cocaine's reinforcing effects were not diminished in SERT(-/-) mice under any of the conditions tested, except for impaired initial acquisition of both food- and cocaine-maintained behavior. These findings support the notion that the DAT, but not the SERT, is critical in mediating the reinforcing effects of cocaine.

The effect of 4% icodextrin solution on adhesiolysis surgery time at the Hartmann’s reversal: a pilot, multicentre, randomized control trial vs lactated Ringer’s solution

A pilot randomized controlled clinical multicentre trail was established to compare intraperitoneal 4% icodextrin (ID) solution with lactated Ringer's solution (LRS) on adhesion formation after Hartmann's procedure. The adhesiolysis surgery time during Hartman's reversal was used as a marker of the severity of adhesions. Patients scheduled for Hartmann's resection were randomized at surgery to either of the two study solutions used as an irrigant during the operation and instilled (1000 ml) at the end of surgery. During the reversal procedure, the time for small bowel adhesiolysis was recorded. On completion of 17 eligible patients, an interim analysis was performed. There were no complications following the use of 4% ID solution. The mean (SD) total adhesiolysis times in patients treated with 4% ID solution and LRS were 30.8 (18.0) min and 47.6 (45.7) min, respectively. The mean reduction of 16.8 min, although greater than expected, was not statistically significant (P = 0.33) because of the large variance in adhesiolysis times. Further statistical analysis showed that to achieve significance for the observed differences and variance, a minimum of 240 patients in each group would be required. Icodextrin treatment resulted in a decreasing trend in adhesiolysis time. The use of 4% ID solution in peritonitis patients seemed to be safe. Because of larger than expected variations in adhesiolysis times, this pilot study was underpowered to meet the study end-point and further statistical modelling estimated that significance cannot be reached within a reasonable time scale. Other models should be used to evaluate the efficacy of anti-adhesive agents.