Automatic extraction of the mid-facial plane for cranio-maxillofacial surgery planning

Recently developed computer applications provide tools for planning cranio-maxillofacial interventions based on 3-dimensional (3D) virtual models of the patient's skull obtained from computed-tomography (CT) scans. Precise knowledge of the location of the mid-facial plane is important for the assessment of deformities and for planning reconstructive procedures. In this work, a new method is presented to automatically compute the mid-facial plane on the basis of a surface model of the facial skeleton obtained from CT. The method matches homologous surface areas selected by the user on the left and right facial side using an iterative closest point optimization. The symmetry plane which best approximates this matching transformation is then computed. This new automatic method was evaluated in an experimental study. The study included experienced and inexperienced clinicians defining the symmetry plane by a selection of landmarks. This manual definition was systematically compared with the definition resulting from the new automatic method: Quality of the symmetry planes was evaluated by their ability to match homologous areas of the face. Results show that the new automatic method is reliable and leads to significantly higher accuracy than the manual method when performed by inexperienced clinicians. In addition, the method performs equally well in difficult trauma situations, where key landmarks are unreliable or absent.

Biochemical characterization of detergent-resistant membranes: a systematic approach

Lateral segregation of cholesterol- and sphingomyelin-rich rafts and glycerophospholipid-containing non-raft microdomains has been proposed to play a role in a variety of biological processes. The most compelling evidence for membrane segregation is based on the observation that extraction with non-ionic detergents leads to solubilization of a subset of membrane components only. However, one decade later, a large body of inconsistent detergent-extraction data is threatening the very concept of membrane segregation. We have assessed the validity of the existing paradigms and we show the following. (i) The localization of a membrane component within a particular fraction of a sucrose gradient cannot be taken as a yardstick for its solubility: a variable localization of the DRMs (detergent-resistant membranes) in sucrose gradients is the result of complex associations between the membrane skeleton and the lipid bilayer. (ii) DRMs of variable composition can be generated by using a single detergent, the increasing concentration of which gradually extracts one protein/lipid after another. Therefore any extraction pattern obtained by a single concentration experiment is bound to be 'investigator-specific'. It follows that comparison of DRMs obtained by different detergents in a single concentration experiment is prone to misinterpretations. (iii) Depletion of cholesterol has a graded effect on membrane solubility. (iv) Differences in detergent solubility of the members of the annexin protein family arise from their association with chemically different membrane compartments; however, these cannot be attributed to the 'brick-like' raft-building blocks of fixed size and chemical composition. Our findings demonstrate a need for critical re-evaluation of the accumulated detergent-extraction data.

Impaired calcium homeostasis, clinical impact

Abnormalities of the calcium homeostasis are, with exception of the neonatal period, not often to diagnose in childhood. However, as the clinical features may not only be quite heterogeneous but also present with a very changing pattern, abnormalities of calcium homeostasis have to be considered in many differential diagnoses. Extracellular fluid calcium or plasma calcium is very carefully controlled by fluxes of calcium, which occur between the extracellular fluid and the skeleton, as well as between gut and the kidneys. Therefore, in this review, first, the factors physiologically regulating calcium homeostasis and bone formation are summarized; and then, the situations in which the plasma calcium level should be measured in daily clinical practices are discussed.

Abnormal collagen fibrils in cartilage of matrilin-1/matrilin-3-deficient mice

Matrilins are oligomeric extracellular matrix adaptor proteins mediating interactions between collagen fibrils and other matrix constituents. All four matrilins are expressed in cartilage and mutations in the human gene encoding matrilin-3 (MATN3) are associated with different forms of chondrodysplasia. Surprisingly, however, Matn3-null as well as Matn1- and Matn2-null mice do not show an overt skeletal phenotype, suggesting a dominant negative pathomechanism for the human disorders and redundancy/compensation among the family members in the knock-out situation. Here, we show that mice lacking both matrilin-1 and matrilin-3 develop an apparently normal skeleton, but exhibit biochemical and ultrastructural abnormalities of the knee joint cartilage. At the protein level, an altered SDS-PAGE band pattern and a clear up-regulation of the homotrimeric form of matrilin-4 were evident in newborn Matn1/Matn3 and Matn1 knock-out mice, but not in Matn3-null mice. The ultrastructure of the cartilage matrix after conventional chemical fixation was grossly normal; however, electron microscopy of high pressure frozen and freeze-substituted samples, revealed two consistent observations: 1) moderately increased collagen fibril diameters throughout the epiphysis and the growth plate in both single and double mutants; and 2) increased collagen volume density in Matn1(-/-)/Matn3(-/-) and Matn3(-/-) mice. Taken together, our results demonstrate that matrilin-1 and matrilin-3 modulate collagen fibrillogenesis in cartilage and provide evidence that biochemical compensation might exist between matrilins.

A new system for computer-aided preoperative planning and intraoperative navigation during corrective jaw surgery

A new system for computer-aided corrective surgery of the jaws has been developed and introduced clinically. It combines three-dimensional (3-D) surgical planning with conventional dental occlusion planning. The developed software allows simulating the surgical correction on virtual 3-D models of the facial skeleton generated from computed tomography (CT) scans. Surgery planning and simulation include dynamic cephalometry, semi-automatic mirroring, interactive cutting of bone and segment repositioning. By coupling the software with a tracking system and with the help of a special registration procedure, we are able to acquire dental occlusion plans from plaster model mounts. Upon completion of the surgical plan, the setup is used to manufacture positioning splints for intraoperative guidance. The system provides further intraoperative assistance with the help of a display showing jaw positions and 3-D positioning guides updated in real time during the surgical procedure. The proposed approach offers the advantages of 3-D visualization and tracking technology without sacrificing long-proven cast-based techniques for dental occlusion evaluation. The system has been applied on one patient. Throughout this procedure, we have experienced improved assessment of pathology, increased precision, and augmented control.

A 3-year survey of assault-related maxillofacial fractures in central Switzerland

AIM: The aim of this study was to analyse the character of assault-related facial fractures in central Switzerland and to compare their prevalence with the data presented in similar reports from other countries. MATERIAL: The present study comprised 65 patients with assault-related maxillofacial fractures treated in the Department of Cranio-Maxillofacial Surgery, University Hospital of Bern between 2000 and 2002. METHODS: The mechanism, the causes of the injuries and the location of the fractures were analysed by reviewing emergency and hospital records. Concomitant injuries were also studied. RESULTS: The mean age of the patients was 33 years with the largest group being below 25 years. The male-to-female ratio was 56:9. The most common causes of assault-related injuries were fights, most frequently facial blows, accounting for 92.5% of all patients. Seventy-six per cent of the fractures occurred in the middle and upper facial skeleton with a predominance of 2:1 for the left side. In 39 patients (60%) surgery was necessary, with a mean hospital stay of 3.3 days. Thirty-five patients (54%) had concomitant injuries. Alcohol and drug abuse was found in 15 patients (23%). CONCLUSION: It seems that mostly young men suffer assault-related maxillofacial injuries. A contributing factor to the increased disposition for violence could be alcohol and drug abuse. Therefore, national prevention programmes for alcohol or drug abuse and addiction might have a positive effect on reducing the incidence of assault-related maxillofacial injuries.

Pediatric craniofacial trauma

PURPOSE: Maxillofacial and skull fractures occur with concomitant injuries in pediatric trauma patients. The aim of this study was to determine the causes and distributions of maxillofacial and skull fractures as well as concomitant injuries of pediatric patients in Switzerland. Results were compared with worldwide studies. MATERIALS AND METHODS: A retrospective review was conducted of 291 pediatric patients with maxillofacial and skull fractures presenting to a level-I trauma center over a 3-year span. Data concerning the mechanism of the accident and the topographic location of the injuries were analyzed. RESULTS: The most common causes were falls (64%), followed by traffic (22%) and sports-related accidents (9%). Fifty-four percent of the fractures occurred in the skull vault and 37% in the upper and middle facial third. One third of the patients (n = 95) suffered concomitant injuries, mostly cerebral concussions (n = 94). CONCLUSIONS: The spectrum of craniofacial injuries is related to the specific developmental stage of the craniofacial skeleton. It is probable that national prevention programs will have a positive effect on reducing the incidence of falls. Standardization of studies is needed for international comparison.

Cervical soft tissue imaging using a mobile CBCT scanner with a flat panel detector in comparison with corresponding CT and MRI data sets

OBJECTIVE: The aim of this study was to evaluate soft tissue image quality of a mobile cone-beam computed tomography (CBCT) scanner with an integrated flat-panel detector. STUDY DESIGN: Eight fresh human cadavers were used in this study. For evaluation of soft tissue visualization, CBCT data sets and corresponding computed tomography (CT) and magnetic resonance imaging (MRI) data sets were acquired. Evaluation was performed with the help of 10 defined cervical anatomical structures. RESULTS: The statistical analysis of the scoring results of 3 examiners revealed the CBCT images to be of inferior quality regarding the visualization of most of the predefined structures. Visualization without a significant difference was found regarding the demarcation of the vertebral bodies and the pyramidal cartilages, the arteriosclerosis of the carotids (compared with CT), and the laryngeal skeleton (compared with MRI). Regarding arteriosclerosis of the carotids compared with MRI, CBCT proved to be superior. CONCLUSIONS: The integration of a flat-panel detector improves soft tissue visualization using a mobile CBCT scanner.

3D C-arm as an alternative modality to CT in postmortem imaging: technical feasibility

OBJECT: The aim of our study was to demonstrate the image quality of the new device using human cadavers, extending the horizon of available imaging modalities in forensic medicine. MATERIALS AND METHODS: Six human cadavers were examined, revealing C-arm data sets of the head, neck thorax, abdomen and pelvis. High-resolution mode was performed with 500 fluoroscopy shots during a 190 degrees orbital movement with a constant tube voltage of 100 kV and a current of 4.6 mA. Based on these data sets subsequent three-dimensional reconstructions were generated. RESULTS: Reconstructed data sets revealed high-resolution images of all skeletal structures in a near-CT quality. The same image quality was available in all reconstruction planes. Artefacts caused by restorative dental materials are less accentuated in CBCT data sets. The system configuration was not powerful enough to generate sufficient images of intracranial structures. CONCLUSION: After the here-demonstrated encouraging preliminary results, the forensic indications that would be suitable for imaging with a 3D C-arm have to be defined. Promising seems the visualization local limited region of interest as the cervical spine or the facial skeleton.

Evaluation of 41calcium as a new approach to assess changes in bone metabolism: effect of a bisphosphonate intervention in postmenopausal women with low bone mass

A new technique was evaluated to identify changes in bone metabolism directly at high sensitivity through isotopic labeling of bone Ca. Six women with low BMD were labeled with 41Ca up to 700 days and treated for 6 mo with risedronate. Effect of treatment on bone could be identified using 41Ca after 4-8 wk in each individual. INTRODUCTION: Isotopic labeling of bone using 41Ca, a long-living radiotracer, has been proposed as an alternative approach for measuring changes in bone metabolism to overcome current limitations of available techniques. After isotopic labeling of bone, changes in urinary 41Ca excretion reflect changes in bone Ca balance. The aim of this study was to validate this new technique against established measures. Changes in bone Ca balance were induced by giving a bisphosphonate. MATERIALS AND METHODS: Six postmenopausal women with diagnosed osteopenia/osteoporosis received a single oral dose of 100 nCi 41Ca for skeleton labeling. Urinary 41Ca/40Ca isotope ratios were monitored by accelerator mass spectrometry up to 700 days after the labeling process. Subjects received 35 mg risedronate per week for 6 mo. Effect of treatment was monitored using the 41Ca signal in urine and parallel measurements of BMD by DXA and biochemical markers of bone metabolism in urine and blood. RESULTS: Positive response to treatment was confirmed by BMD measurements, which increased for spine by +3.0% (p = 0.01) but not for hip. Bone formation markers decreased by -36% for bone alkaline phosphatase (BALP; p = 0.002) and -59% for procollagen type I propeptides (PINP; p = 0.001). Urinary deoxypyridinoline (DPD) and pyridinoline (PYD) were reduced by -21% (p = 0.019) and -23% (p = 0.009), respectively, whereas serum and urinary carboxy-terminal teleopeptides (CTXs) were reduced by -60% (p = 0.001) and -57.0% (p = 0.001), respectively. Changes in urinary 41Ca excretion paralleled findings for conventional techniques. The urinary 41Ca/40Ca isotope ratio was shifted by -47 +/- 10% by the intervention. Population pharmacokinetic analysis (NONMEM) of the 41Ca data using a linear three-compartment model showed that bisphosphonate treatment reduced Ca transfer rates between the slowly exchanging compartment (bone) and the intermediate fast exchanging compartment by 56% (95% CI: 45-58%). CONCLUSIONS: Isotopic labeling of bone using 41Ca can facilitate human trials in bone research by shortening of intervention periods, lowering subject numbers, and having easier conduct of cross-over studies compared with conventional techniques.

Management of fragility fractures in Switzerland: results of a nationwide survey

A nationwide survey was conducted in Switzerland to assess the quality level of osteoporosis management in patients aged 50 years or older presenting with a fragility fracture to the emergency ward of the participating hospitals. Eight centres recruited 4966 consecutive patients who presented with one or more fractures between 2004 and 2006. Of these, 3667 (2797 women, 73.8 years old and 870 men, 73.0 years old in average) were considered as having a fragility fracture and included in the survey. Included patients presented with a fracture of the upper limbs (30.7%), lower limbs (26.4%), axial skeleton (19.5%) or another localisation, including malleolar fractures (23.4%). Thirty-two percent reported one or more previous fractures during adulthood. Of the 2941 (80.2%) hospitalised women and men, only half returned home after discharge. During diagnostic workup, dual x-ray absorptiometry (DXA) measurement was performed in 31.4% of the patients only. Of those 46.0% had a T-score < or =-2.5 SD and 81.1% < or =-1.0 SD. Osteoporosis treatment rate increased from 26.3% before fracture to 46.9% after fracture in women and from 13.0% to 30.3% in men. However, only 24.0% of the women and 13.8% of the men were finally adequately treated with a bone active substance, generally an oral bisphosphonate, with or without calcium / vitamin D supplements. A positive history of previous fracture vs none increased the likelihood of getting treatment with a bone active substance (36.6 vs 17.9%, ? 18.7%, 95% CI 15.1 to 22.3, and 22.6 vs 9.9%, ? 12.7%, CI 7.3 to 18.5, in women and men, respectively). In Switzerland, osteoporosis remains underdiagnosed and undertreated in patients aged 50 years and older presenting with a fragility fracture.

Loss of alpha10beta1 integrin expression leads to moderate dysfunction of growth plate chondrocytes

Integrin alpha10beta1 is a collagen-binding integrin expressed on chondrocytes. In order to unravel the role of the alpha10 integrin during development, we generated mice carrying a constitutive deletion of the alpha10 integrin gene. The mutant mice had a normal lifespan and were fertile but developed a growth retardation of the long bones. Analysis of the skeleton revealed defects in the growth plate after birth characterized by a disturbed columnar arrangement of chondrocytes, abnormal chondrocyte shape and reduced chondrocyte proliferation. Electron microscopy of growth plates from newborn mice revealed an increased number of apoptotic chondrocytes and reduced density of the collagen fibrillar network compared to these structures in control mice. These results demonstrate that integrin alpha10beta1 plays a specific role in growth plate morphogenesis and function.

Dental injuries in association with facial fractures

PURPOSE: The aim of the study was to investigate the association between dental injuries and facial fractures. MATERIALS AND METHODS: We performed a prospective study of 273 patients examined at a level 1 trauma center in Switzerland from September 2005 until August 2006 who had facial fractures. Medical history and clinical and radiologic examination findings were recorded to evaluate demographics, etiology, presentation, and type of facial fracture, as well as its relationship to dental injury site and type. RESULTS: In 273 patients with dentition, we recorded 339 different facial fractures. Of these patients, 130 (47.5%) sustained a fracture in the non-tooth-bearing region, 44 (16%) had a fractured maxilla, and 65 (24%) had a fractured mandible. Among 224 patients with dentition who had a facial fracture in only 1 compartment, 140 injured teeth were found in 50 patients. Of 122 patients with an injury limited to the non-tooth-bearing facial skeleton, 12 sustained dental trauma (10%). In patients with fractures limited to the maxilla (n = 41), 6 patients had dental injuries (14.5%). In patients with fractures to the mandible (n = 61), 24 sustained dental injuries (39%). When we compared the type of tooth lesion and the location, simple crown fractures prevailed in both jaws. Patients with a fracture of the mandible were most likely to have a dental injury (39.3%). The highest incidence of dental lesions was found in the maxilla in combination with fractures of the lower jaw (39%). This incidence was even higher than the incidence of dental lesions in the lower jaw in combination with fractures of the mandible (24%). CONCLUSIONS: Knowledge of the association of dental injuries and maxillofacial fractures is a basic tool for their prevention. Our study showed that in cases of trauma with mandibular fracture, the teeth in the upper jaw might be at higher risk than the teeth in the lower jaw. Further larger-scale studies on this topic could clarify this finding and may provide suggestions for the amelioration of safety devices (such as modified bicycle helmets).

QSAR Studies on Thiazolidines: A Biologically Privileged Scaffold

A large number of drugs and biologically relevant molecules contain heterocyclic systems. Often the presence of hetero atoms or groupings imparts preferential specificities in their biological responses. Amongst the heterocyclic systems, thiazolidine is a biologically important scaffold known to be associated with several biological activities. Some of the prominent biological responses attributed to this skeleton are antiviral, antibacterial, antifungal, antihistaminic, hypoglycemic, anti-inflammatory activities. This diversity in the biological response profiles of thiazolidine has attracted the attention of many researchers to explore this skeleton to its multiple potential against several activities. Many of these synthetic and biological explorations have been subsequently analyzed in detailed quantitative structure-activity relationship (QSAR) studies to correlate the respective structural features and physicochemical properties with the activities to identify the important structural components in deciding their activity behavior. In this, drugs or any biologically active molecules may be viewed as structural frames consisting of strategically positioned functional groups that will interact effectively with the complementary groups/sites of the receptor. With this in focus, the present article reviews the QSAR studies of diverse biological activities of the thiazolidines published during the past decade.

Automatic Data Normalization and Parameterization for Optical Motion Tracking

Methods for optical motion capture often require timeconsuming manual processing before the data can be used for subsequent tasks such as retargeting or character animation. These processing steps restrict the applicability of motion capturing especially for dynamic VR-environments with real time requirements. To solve these problems, we present two additional, fast and automatic processing stages based on our motion capture pipeline presented in [HSK05]. A normalization step aligns the recorded coordinate systems with the skeleton structure to yield a common and intuitive data basis across different recording sessions. A second step computes a parameterization based on automatically extracted main movement axes to generate a compact motion description. Our method does not restrict the placement of marker bodies nor the recording setup, and only requires a short calibration phase.