Mlck1a is expressed in zebrafish thrombocytes and is an essential component of thrombus formation.

BACKGROUND: We have used the advantages of the zebrafish model system to demonstrate which of the vertebrate myosin light chain kinase (MLCK) genes is expressed in thrombocytes and important for thrombus formation. METHODS AND RESULTS: Here we report that Mlck1a is an essential component of thrombus formation. Phylogenetic data revealed four zebrafish orthologous for three human MLCK genes. To investigate expression of the zebrafish mlck genes in thrombocytes we compared GFP-tagged platelets with other cells by microarray analysis, and showed that mlck1a expression was 4.5-fold enriched in platelets. Furthermore, mlck1a mRNA and mRNA for the platelet-specific cd41 co-localized in thrombi. Expression of other mlck subtypes was lower in GFP-tagged platelets (mlck1b; 0.77-fold enriched) and absent in thrombi (mlck1b, -2, -3). To investigate the role of Mlck1a in thrombus formation, we knocked down mlck1a using two morpholinos. This resulted in impaired morphology changes of platelets adhering on fibrinogen. In a thrombosis model, in which thrombocytes adhere to the vessel wall damaged by laser irradiation, thrombus formation was slowed down in mlck1a-deficient embryos. CONCLUSION: We conclude that Mlck1a is the subtype of MLCK that contributes to platelet shape change and thrombus formation.

The prevalence of intolerance for low-dose acetylsalicylacid in the secondary prevention of atherothrombosis.

Daily low-dose acetylsalicylacid (ASA) is prescribed to patients with atherothrombosis frequently to prevent vascular complications. In reports on complications and side effects of low-dose ASA use in the literature there is a range of definitions. We explored the incidence, characteristics and consequences of symptoms suggestive of ASA intolerance in patients on low-dose ASA. General practitioners and specialists in 105 centres were asked to review their patient files for the last 10 consecutive patients who were prescribed ASA. Participating patients completed a questionnaire about their current ASA use (doctors completed the questionnaire together with the patients), use of co-medication and symptoms suggestive of ASA intolerance. A total of 947 patients were included in this study. Sixty patients (6.6%) had ceased ASA treatment, predominantly because of the occurrence of side effects suspected to be caused by ASA use. A quarter of the patients concomitantly used an anti-acid agent. Of the 947 patients, 271 (30.6%) indicated symptoms during ASA intake. The most common symptoms were related to the gastrointestinal tract (25.1%). In patients prescribed a low-dose of ASA monotherapy, side effects suggestive of intolerance are common. More awareness should be created to detect and treat these symptoms, because the occurrence of side effects is the most important reason for patients to discontinue ASA treatment.

Construct validity of the LapSim: can the LapSim virtual reality simulator distinguish between novices and experts?

BACKGROUND: Virtual reality simulators may be invaluable in training and assessing future endoscopic surgeons. The purpose of this study was to investigate if the results of a training session reflect the actual skill of the trainee who is being assessed and thereby establish construct validity for the LapSim virtual reality simulator (Surgical Science Ltd., Gothenburg, Sweden). METHODS: Forty-eight subjects were assigned to one of three groups: 16 novices (0 endoscopic procedures), 16 surgical residents in training (>10 but <100 endoscopic procedures), and 16 experienced endoscopic surgeons (>100 endoscopic procedures). Performance was measured by a relative scoring system that combines single parameters measured by the computer. RESULTS: The higher the level of endoscopic experience of a participant, the higher the score. Experienced surgeons and surgical residents in training showed statistically significant higher scores than novices for both overall score and efficiency, speed, and precision parameters. CONCLUSIONS: Our results show that performance of the various tasks on the simulator corresponds to the respective level of endoscopic experience in our research population. This study demonstrates construct validity for the LapSim virtual reality simulator. It thus measures relevant skills and can be integrated in an endoscopic training and assessment program.

Controversies in paraesophageal hernia repair: a review of literature.

BACKGROUND: The surgical repair of paraesophageal hiatal hernias (PHH) can be performed by endoscopic means, but the procedure is not standardized and results have not been evaluated systematically so far. The aim of this review article was to clarify controversial subjects on the surgical approach and technique, i.e., recurrence rate after conventional versus laparoscopic PHH treatment, results of mesh reinforcement of the cruroplasty, the necessity for additional antireflux surgery, and indications for an esophageal lengthening procedure. METHODS: An electronic Medline search was performed to identify all publications reporting on laparoscopic and conventional PHH surgery. The computer search was followed by additional hand searches in books, journals, and related articles. All types of publications were evaluated because of a lack of high-level evidence studies such as randomized controlled trials. Critical analysis followed for all articles describing a study population of >10 patients and those reporting postoperative outcome. RESULTS: A total of 32 publications were reviewed. Randomized controlled trials comparing laparoscopic and open techniques could not be identified. Nineteen of the publications described the results of retrospective series. Therefore, most of the studies retrieved were low in hierarchy of evidence (level II-c or lower). The overall median hospital time as published was 3 days for patients operated laparoscopically and 10 days in the conventional group. Postoperative complications, such as pneumonia, thrombosis, hemorrhage, and urinary and wound tract infections, appeared to be more frequent after conventional surgery. Follow-up was longer for conventional surgery (median 45 months versus 17.5 months after the laparoscopic technique). Recurrence rates reported were higher in patients operated conventionally (median 9.1% versus 7.0% for patients operated laparoscopically). Recurrences after PHH repair may decrease with usage of mesh in the hiatus, although uniform criteria for this procedure are lacking. No conclusions could be drawn regarding the necessity for an additional antireflux procedure. Furthermore, uniform specific indications for the need of an esophageal lengthening procedure or preoperative assessment methods for shortened esophagus could not be detected. CONCLUSION: Treatment based on standardized protocols for preoperative assessment and postoperative follow-up is required to clarify the current controversies.