Automatic fusion of lateral cephalograms and digital volume tomography data-perspective for combining two modalities in the future.

OBJECTIVES: This article investigates the combination of three-dimensional (3D) digital volume tomography data with two-dimensional (2D) cephalograms in dentomaxillofacial imaging. METHODS: An automatic hierarchical method to adjust the geometrical relations of these two modalities is presented. The approach is tested on phantom and patient case data, where the feasibility, usability and potential possibilities of the presented innovative method are highlighted. Digitally reconstructed radiographs are computed by casting rays through the 3D volume to get a 2D projection of the volume to produce realistic simulated cephalograms. Different similarity measures are considered based on variations of statistical and deterministic optimization procedures. Stability, precision and accuracy of the method are investigated. RESULTS: The presented algorithm demonstrates a reasonable solution of the corresponding 2D/3D registration problem. Exemplary results from phantom and patient case data are presented. Tooth movement could be determined, in contrast to the 2D lateral cephalogram, separated for each side in all three spatial directions. CONCLUSIONS: Achieved results are highlighted from a clinical point of view and demonstrate the clinical benefit in daily praxis.

Assessment of apical periodontitis by MRI: a feasibility study.

PURPOSE: The purpose of this clinical feasibility study was to evaluate the applicability of magnetic resonance imaging (MRI) for the assessment of apical periodontitis in direct comparison with cone beam CT (CBCT). MATERIALS AND METHODS: 19 consecutive patients (average age 43 ±â€Š13 years) with 34 lesions in total (13 molars, 14 premolars and 7 front teeth) were enrolled in this feasibility study. Periapical lesions were defined as periapical radiolucencies (CBCT) or structural changes in the spongy bone signal (MRI), which were connected with the apical part of a root and with at least twice the width of the periodontal ligament space. The location and dimension of the lesions were compared between MRI and CBCT. RESULTS: While mainly mineralized tissue components such as teeth and bone were visible with CBCT, complimentary information of the soft tissue components was assessable with MRI. The MRI images provided sufficient diagnostic detail for the assessment of the main structures of interest. Heterogeneous contrast was observed within the lesion, with often a clear enhancement close to the apical foramen and the periodontal gap.  No difference for lesion visibility was observed between MRI and CBCT. The lesion dimensions corresponded well, but were slightly but significantly overestimated with MRI. A heterogeneous lesion appearance was observed in several patients. Four patients presented with a well circumscribed hyperintense signal in the vicinity of the apical foramen. CONCLUSION: The MRI capability of soft tissue characterization may facilitate detailed analysis of periapical lesions. This clinical study confirms the applicability of multi-contrast MRI for the identification of periapical lesions. KEY POINTS: MRI can be applied for the identification of periapical lesions without ionizing radiation exposure. MRI might facilitate more detailed characterization of periapical lesions. MRI might provide more accurate lesion dimensions as X-ray-based methods.

Student distress in clinical workplace learning: differences in social comparison behaviours.

In medical education, student distress is known to hamper learning and professional development. To address this problem, recent studies aimed at helping students cope with stressful situations. Undergraduate students in clinical practice frequently use experiences of surrounding peers to estimate their abilities to master such challenging situations. This use of the experiences of others, known as social comparison, may affect student distress both positively and negatively. To find characteristics of a beneficial use of social comparison, we examined differences in comparison behaviours between students expressing low and high levels of distress. The participants in our study, response rate 93% (N = 301/321), were all medical students in their first year in clinical practice. They completed the General Health Questionnaire (GHQ-12) to measure distress, and three separate questionnaires to measure: (1) orientation to comparison, (2) motive for comparison, and (3) interpretation of comparison. Differences were analysed using multivariate analysis of variance. Although all students were oriented towards social comparison, the analyses showed that this orientation was less apparent among low-distress students. Besides, the low-distress students were less inclined to use motives indicative for comparisons with peers perceived as performing worse and were less negative in the interpretations of their comparisons. As social comparison is frequently used among all students, we recommend to make them aware of their comparison behaviours and inform them about the pros and cons of the distinguished aspects of the comparison process.

Evidence-based practice for individuals or groups: let's make a difference.

The aim of applying science into practice is to deliver high-quality health care. Thinking about teaching the necessary accompanying skills, a distinction can be made between using evidence for individual patient care and using scientific knowledge for the development of protocols or guidelines for groups of patients or professionals. In this paper, these two ways of applying science into practice are being considered. We plea for explicating the differences between the individual patient and a group of patients or professionals when applying scientific knowledge in the decision-making process. The acknowledgment of these differences facilitates the teaching of the accompanying competences and different CanMEDS roles.

Ultrashort echo time (UTE) MRI for the assessment of caries lesions.

OBJECTIVE: Direct in vivo MRI of dental hard tissues by applying ultrashort echo time (UTE) MRI techniques has recently been reported. The objective of the presented study is to clinically evaluate the applicability of UTE MRI for the identification of caries lesions. METHODS: 40 randomly selected patients (mean age 41 ± 15 years) were enrolled in this study. 39 patients underwent a conventional clinical assessment, dental bitewing X-ray and a dental MRI investigation comprising a conventional turbo-spin echo (TSE) and a dedicated UTE scan. One patient had to be excluded owing to claustrophobia. In four patients, the clinical treatment of the lesions was documented by intraoral pictures, and the resulting volume of the cavity after excavation was documented by dental imprints and compared with the MRI findings. RESULTS: In total, 161 lesions were identified. 157 (97%) were visible in the UTE images, 27 (17%) in the conventional TSE images and 137 (85%) in the X-ray images. In total, 14 teeth could not be analysed by MR owing to artefacts caused by dental fillings. All lesions appear significantly larger in the UTE images as compared with the X-ray and TSE images. In situ measurements confirm the accuracy of the lesion dimensions as observed in the UTE images. CONCLUSION: The presented data provide evidence that UTE MR imaging can be applied for the identification of caries lesions. Although the current data suggest an even higher sensitivity of UTE MRI, some limitations must be expected from dental fillings.

Peer influence on students' estimates of performance: social comparison in clinical rotations.

CONTEXT: During clinical rotations, students move from one clinical situation to another. Questions exist about students' strategies for coping with these transitions. These strategies may include a process of social comparison because in this context it offers the student an opportunity to estimate his or her abilities to master a novel rotation. These estimates are relevant for learning and performance because they are related to self-efficacy. We investigated whether student estimates of their own future performance are influenced by the performance level and gender of the peer with whom the student compares him- or herself. METHODS: We designed an experimental study in which participating students (n = 321) were divided into groups assigned to 12 different conditions. Each condition entailed a written comparison situation in which a peer student had completed the rotation the participant was required to undertake next. Differences between conditions were determined by the performance level (worse, similar or better) and gender of the comparison peer. The overall grade achieved by the comparison peer remained the same in all conditions. We asked participants to estimate their own future performance in that novel rotation. Differences between their estimates were analysed using analysis of variance (ANOVA). RESULTS: Students' estimates of their future performance were highest when the comparison peer was presented as performing less well and lowest when the comparison peer was presented as performing better (p < 0.001). Estimates of male and female students in same-gender comparison conditions did not differ. In two of three opposite-gender conditions, male students' estimates were higher than those of females (p < 0.001 and p < 0.05, respectively). CONCLUSIONS: Social comparison influences students' estimates of their future performance in a novel rotation. The effect depends on the performance level and gender of the comparison peer. This indicates that comparisons against particular peers may strengthen or diminish a student's self-efficacy, which, in turn, may ease or hamper the student's learning during clinical rotations. The study is limited by its experimental design. Future research should focus on students' comparison behaviour in real transitions.

Human cathelicidin peptide LL37 inhibits both attachment capability and biofilm formation of Staphylococcus epidermidis.

AIMS: The aim of this work was to investigate the possible effect of human cathelicidin antimicrobial peptide LL37 on biofilm formation of Staphylococcus epidermidis, a major causative agent of indwelling device-related infections. METHODS AND RESULTS: We performed initial attachment assay and biofilm formation solid surface assay in microtitre plates, as well as growth experiment in liquid medium using laboratory strain Staph. epidermidis ATCC35984. We found that already a low concentration of the peptide LL37 (1 mg l(-1)) significantly decreased both the attachment of bacteria to the surface and also the biofilm mass. No growth inhibition was observed even at 16 mg l(-1) concentration of LL37, indicating a direct effect of the peptide on biofilm production. CONCLUSIONS: As biofilm protects bacteria during infections in humans and allows their survival in a hostile environment, inhibition of biofilm formation by LL37 may have a key role to prevent bacterial colonization on indwelling devices. SIGNIFICANCE AND IMPACT OF THE STUDY: Our findings suggest that this host defence factor can be a potential candidate in prevention and treatment strategies of Staph. epidermidis infections in humans.

Learning strategies during clerkships and their effects on clinical performance.

BACKGROUND: Previous research revealed relationships between learning strategies and knowledge acquisition. During clerkships, however, students' focus widens beyond mere knowledge acquisition as they further develop overall competence. This shift in focus can influence learning strategy use. AIM: We explored which learning strategies were used during clerkships and their relationship to clinical performance. METHODS: Participants were 113 (78%) clerks at the university hospital or one of six affiliated hospitals. Learning strategies were assessed using the 'Approaches to Learning at Work Questionnaire' (deep, surface-rational and surface-disorganised learning). Clinical performance was calculated by taking the mean of clinical assessment marks. The relationship between learning strategies and clinical performance was explored using regression analysis. RESULTS: Most students (89%) did not clearly prefer a single learning strategy. No relationship was found between learning strategies and clinical performance. DISCUSSION: Since overall competence comprises integration of knowledge, skills and professional behaviour, we assume that students without a clear preference use more than one learning strategy. Finding no relationship between learning strategies and clinical performance reflects the complexity of clinical learning. Depending on circumstances it may be important to obtain relevant information quickly (surface-rational) or understand material thoroughly (deep). In future research we will examine when and why students use different learning strategies.

Bacteria isolated from the different developmental stages and larval organs of the obligate parasitic fly, Wohlfahrtia magnifica (Diptera: Sarcophagidae).

Wohlfahrtia magnifica (Diptera: Sarcophagidae) is the major myiasis-causing fly species in the whole of Eurasia for most important domestic animals. The aim of the present work was to obtain data on the culturable bacteria isolated under aerobic conditions from this fly: bacteria were isolated from all developmental stages (larvae, pupa, and imago) of Wohlfahrtia magnifica, and the third-stage larval organs were also sampled. To determine the possible antagonistic effects between the dominant bacterial groups, an antibiosis assay was carried out. Plating and isolation of bacteria was performed by classical microbiological methods. Characterization of the isolated strains was carried out via a polyphasic approach; classical phenotypic tests, chemotaxonomical examinations, and 16S rDNA sequence analyses were also applied. In the case of maggot macerate samples, members of the family Enterobacteriaceae were characteristic. Members of a new genus (Schineria) belonging to the gamma subdivision of proteobacteria were also isolated. According to our data, the shifts in the Schineria and Proteus populations within the larvae are strongly influenced by their interactions with each other and among the members of the family Enterobacteriaceae. The pupa and imago samples contained several other Gram-negative bacteria (Stenotrophomonas, Brevundimonas, etc.). Among Gram-positive bacteria, in all maggot macerate samples, members of the genus Bacillus and the Arthrobacter-Micrococcus group of actinobacteria were dominant (neither of them was a producer or sensitive to the compounds of other microorganisms), and bacteria related to the genus Corynebacterium were also found. From the larvae Aureobacterium liquefaciens and Enterococcus faecalis were isolated, and from the pupae Dietzia maris and Enterococcus faecalis. In the samples of third-stage larval organs, the dominant groups were the same as in the third-stage larval macerate sample; however, several additional genera/species were observed (Rhodococcus fascians, Streptomyces sp., Rathayibacter sp., Bacillus thuringiensis/cereus).

In vitro rearing of the screwworm fly Wohlfahrtia magnifica.

Wohlfahrtia magnifica (Schiner) (Diptera: Sarcophagidae) is the main agent of traumatic myiasis in many European, African and Asian countries. Although it can be reared in vivo without technical difficulty, such rearing presents ethical problems. Studies were therefore made of in vitro rearing to facilitate development of laboratory colonies that could be used in a wide range of biological, physiological and applied studies of W. magnifica, particularly in the long period of the year when natural populations of the fly are unavailable for study. Parental colonies of W. magnifica were established from larvae collected from natural infestations of sheep and cattle in central Hungary. First stage larvae were harvested from gravid females and were reared in groups of 5-20 on one of six artificial diets. The diets were based on various combinations of five to seven of eight ingredients: water, agar, blood (heparinized or dried), ground meat, egg yolk, low-fat milk powder, yeast and 10% formol. The larvae were incubated on the diets at 37 degrees C. There was no mortality of first stage larvae, which appeared to feed together in foci, in a natural manner. However, during the second stage, and especially after renewal of diet associated with disturbance of the larvae, many larvae began to disperse, crawling over the surface of the media and feeding less intensively. Mortality of larvae during all larval stadia was 64-98%, compared to 33% in batches of third stage larvae collected from natural infestations. The mean weights of puparia from artificial diets ranged from 38.7 to 59.3 mg, compared to 92.2 mg of puparia from larvae collected from natural infestations. There was a high mortality in the pupal stage, from 61 to 100%. Only a maximum of 6% of first stage larvae were successfully reared to the adult stage. Further studies are needed to identify factors present or absent in the diets that contributed to the present poor development of W. magnifica in vitro.

Laparoscopic surgical concepts of morbid obesity.

BACKGROUND: According to the WHO, obesity and obesity with associated morbidity constitute a chronic, multi-factorial condition requiring treatment. Conservative treatment has been shown in long-term studies to be ineffective in morbid obesity. Surgical treatments break down into restrictive, malabsorptive, combined restrictive and malabsorptive or motility-reducing procedures. METHOD AND RESULTS: Laparoscopic implantation of an adjustable gastric band is an efficient restrictive measure for treating the majority of patients with this condition. The adjustable gastric band enables weight loss and food intake to be adapted to the individual patient's need. Of these patients, 80-90% can expect to lose 55-70% of their excess weight. Vertical banded gastroplasty is losing ground among the restrictive options. Preliminary experiences are encouraging, but the long-term results are disappointing when assessed by the standard criteria. Gastric bypass is gaining ground in Europe and is a standard procedure in the USA. This operation is estimated to give a 70-80% loss in excess weight, and provides a better quality of life than do restrictive procedures. The biliopancreatic diversion with duodenal switch combines a sleeve gastrectomy with a duodeno-ileal switch to achieve maximum weight loss. Consistent excess weight loss of between 70% and 80% is achieved, with acceptable decreased long-term nutritional complications. The laparoscopic approach to this procedure has successfully created a surgical technique with optimum benefit and minimal morbidity, especially in the super-obese patient. Intra-gastric stimulation is the least invasive surgical procedure at present. However, the excess weight loss is lowest with this method, at only 32% in the first 2 years after the operation. CONCLUSION: Provided that safety recommendations are observed, laparoscopic operations for obesity have a fairly low risk. The mortality rate in centres with experienced staff is less than 0.3%. The death rate due to untreated morbid obesity is significantly higher than in a comparable group of patients after surgery.

[Development, state of the art and future perspectives of surgery for morbid obesity]. / Entwicklung, heutiger Stand und Zukunftsaussichten der Adipositaschirurgie.

Obesity is the most common form of malnutrition and morbid obesity is increasingly recognized as a major health concern. Drug treatments of the morbid obese have entirely failed in the long run. These circumstances have constituted incentives for surgeons to develop techniques resulting in malabsorptive or restrictive effects on food intake. Several techniques achieve weight loss through both these mechanisms and most likely also by changing the gastrointestinal signalling system. Within the last 50 years surgery for morbid obesity has been developed stepwise, like other surgical methods. More than 50 surgical anti-obesity techniques have been described. Half a dozen techniques have been left over and are performed mainly laparoscopically now a days. The outcome of these techniques over the last 30 years is reported in this article. It is the aim to illustrate that bariatric surgery is safe and so far more long-term efficient than any other technique available for the treatment of morbid obesity.

[Bariatric surgery -- stereotypes and paradigms]. / Adipositaschirurgie im interdisziplinären und rechtlichen Spannungsfeld.

Many physicians regard obesity as a sin and treat fat patients with disdain befitting a moral leper. Non-bariatric physicians, being a product of our culture, seem more likely to have an obesity paradigm close to that of the public. Many members of the public regard obesity surgery as dangerous. Many insurers reject morbid obese patients from bariatric surgical treatment with the paradigmal statement that obesity is totally the fault of a fat person. These medical experts do not accept obesity as a disease (which WHO does) and therefore social courts also reject applications of patients who want to undergo bariatric surgery. Morbid obesity is a multifactorial problem with genetic, biochemical, hormonal, environmental, behavioral and cultural elements. It is recognized as an extreme health hazard which is rarely the result of an aberrant moral problem or true addictive behavior. We need to change effectively the negative paradigms towards obesity and its surgery from some of our colleagues, hospital administration, medical insurers and the public. The existing prejudices are not acceptable.

[Criteria for selection of patients for bariatric surgery]. / Kriterien zur Selektion von Patienten für bariatrische Eingriffe.

Because of the high prevalence of co-morbid conditions and poor life expectancy a Body Mass Index (BMI) of 40 kg/m(2) or more is an indication for surgery in a fully informed, consenting adult in optimal medical condition to tolerate general anaesthesia. Patients with BMI of 35-40 kg/m(2) and the existence of one or more serious obesity-related conditions ameliorated by weight loss, such as hypertension, pulmonary insufficiency, non-insulin-dependent diabetes mellitus etc., are also candidates for surgical treatment. The bariatric surgeon should use these international criteria as guidelines only, not strict rules. Attempts on the part of internists and more frequently insurance carriers to require documented failure of previous non-operative treatment is not meaningful.

[Restrictive procedures in the treatment of morbid obesity -- vertical banded gastroplasty vs. adjustable gastric banding]. / Gastrorestriktive Operationstechniken zur Behandlung der morbiden Adipositas -- Vertikale bandverstärkte Gastroplastik vs. bandverstellbare Gastroplastik.

Vertical banded gastroplasty (VBG) has been in clinical use since 1979 and the adjustable gastric banding (AGB) since 1985. The aim of this study was to compare the outcome, short- and long-term complications of the two procedures. Within a period of 9 years (1992-2001) 1 011 gastric restrictive procedures were performed by two surgeons in the course of a prospective nonrandomized comparative trial. 563 VBG's via laparotomy and 448 laparoscopic AGB's were included into the study. The mean BMI of the patients was 46 kg/m 2 in both groups. The mean duration of follow up was 60 months (range 6 to 108 months). No statistical significant difference in outcome in terms of weight loss, reduction of co-morbidity and improvement in quality of life following ASGB or VBG was observed. The hospital mortality rate was 0.3 % (2 VBG, 1 AGB). The overall reintervention rate for long-term complications was 15.6 % for the VBG and 7 % for the AGB group (p < 0.0001). The AGB is entirely reversible and the less invasive procedure preserving an intact anatomy of the stomach. A trend in favour of the AGB is observed.

[Malabsorption methods in bariatric surgery]. / Malabsorptionsmethoden in der bariatrischen Chirurgie.

In Europe, the incidence of morbid obesity amounts approximately 1% of a nation's population. At the time being, a surgical procedure represents the only effective long-term therapy of morbid obesity. In this regard, the gastric bypass is the most common surgical method in the USA, also gaining relevancy in Europe. The development, the basic principle and the actual operation technique are shown. The mode of functioning, complications, surgical alternatives, risks, results and outcome are discussed. Over the past years, bariatric procedures and techniques have been improved, which resulted in a reduction of the risk and in an improvement of the results. Long- term success can be achieved regarding weight reduction and decrease of comorbidities. The gastric bypass is a safe and effective surgical procedure in the treatment of morbid obesity.

[Intragastric stimulation (IGS) for treatment of morbid obesity]. / Intragastrale Stimulation als erste nichtrestriktive und nichtmalabsorptive Behandlungsmethode der morbiden Adipositas.

The technique of implantable gastric stimulator (IGS(R)) placement for treatment of morbid obesity is described. There are three components of the IGS, the programming system, the lead and the electrical stimulator itself. It is placed in the anterior abdominal wall. It is connected to the bioplar lead that is positioned in the muscle wall of the stomach. The nominal parameters were: pulse width 208 micro sec 24 hours per day, pulse rate 40 Hertz and amplitude 6.2-10.0 mA. Fourty eight patients have been treated using techniques that were developed and refined around the world in a prospective open study. 32 and 7 patients, resp. were available for investigation after 6 and 15 months. Twenty-seven (56 %) intra-operative gastric penetrations occurred, as noted on operative gastroscopy, without any clinical sequelae. Six patients (12 %) showed lead dislodgements and a new procedure for lead replacement. There were no operative deaths. All procedures were successfully completed laparoscopically. Two connections required revision (4 %) because the leads were not fully inserted into the lead connector of the generator. No abscess formation or severe complication were noted. The excessive weight loss after 15 months ranged to 32 %. The operation for IGS placement is safe and simple to perform. Attention to technical details is essential for safe performance of the procedure.

A common polymorphism in the promoter of UCP2 is associated with decreased risk of obesity in middle-aged humans.

Obesity is the most common nutritional disorder in Western society. Uncoupling protein-2 (UCP2) is a recently identified member of the mitochondrial transporter superfamily that is expressed in many tissues, including adipose tissue. Like its close relatives UCP1 and UCP3, UCP2 uncouples proton entry in the mitochondrial matrix from ATP synthesis and is therefore a candidate gene for obesity. We show here that a common G/A polymorphism in the UCP2 promoter region is associated with enhanced adipose tissue mRNA expression in vivo and results in increased transcription of a reporter gene in the human adipocyte cell line PAZ-6. In analyzing 340 obese and 256 never-obese middle-aged subjects, we found a modest but significant reduction in obesity prevalence associated with the less-common allele. We confirmed this association in a population-based sample of 791 middle-aged subjects from the same geographic area. Despite its modest effect, but because of its high frequency (approximately 63%), the more-common risk allele conferred a relatively large population-attributable risk accounting for 15% of the obesity in the population studied.

Evaluation of health status and quality of life after bariatric surgery: comparison of standard Roux-en-Y gastric bypass, vertical banded gastroplasty and laparoscopic adjustable silicone gastric banding.

BACKGROUND: This study is a trial to compare the effects and outcomes of three different bariatric procedures performed in two centers. Standard Roux-en-Y gastric bypass was performed by Dr. Norman Samuels in Fort Lauderdale (Florida); vertical banded gastroplasty and laparoscopic adjustable silicone gastric banding were done in Hallein (Salzburg) by Dr. Emanuel Hell and Dr. Karl Miller. METHODS: In a prospective comparative study 30 matched patients from each group were followed to assess post-operative improvement in health status and quality of life, to compare the three different techniques. The Bariatric Analysis and Reporting Outcome System (BAROS) as described by Oria and Moorehead has been used for evaluation. RESULTS: The observation time was at least 3 years (3 to 8 years) in each individual case. A significant increase in quality of life and health status in 75% of the surgically-treated patients was observed when compared with a non-operated control group of morbidly obese patients. CONCLUSIONS: By utilizing BAROS it has been found possible to compare the results of different procedures done by different surgeons with different techniques, utilizing patients from different cultures and with different languages. The results of this comparative study favor the standard gastric bypass for the treatment of morbid obesity. This operation is superior to purely gastric restrictive procedures in weight loss and improvement of quality of life.