Scattering States and Symmetries in the Matrix Model and Two Dimensional String Theory

We study the correspondence between the linear matrix model and the interacting nonlinear string theory. Starting from the simple matrix harmonic oscillator states, we derive in a direct way scattering amplitudes of 2-dimensional strings, exhibiting the nonlinear equation generating arbitrary N-point tree amplitudes. An even closer connection between the matrix model and the conformal string theory is seen in studies of the symmetry algebra of the system.Comment: 25 pages (Phyzzx), Brown-HET-87

Compromised Blood-Brain Barrier Junctions Enhance Melanoma Cell Intercalation and Extravasation

Melanoma frequently metastasises to the brain, and a detailed understanding of the molecular and cellular mechanisms underlying melanoma cell extravasation across the blood-brain barrier (BBB) is important for preventing brain metastasis formation. Making use of primary mouse brain microvascular endothelial cells (pMBMECs) as an in vitro BBB model, we imaged the interaction of melanoma cells into pMBMEC monolayers. We observed exclusive junctional intercalation of melanoma cells and confirmed that melanoma-induced pMBMEC barrier disruption can be rescued by protease inhibition. Interleukin (IL)-1β stimulated pMBMECs or PECAM-1-knockout (-ko) pMBMECs were employed to model compromised BBB barrier properties in vitro and to determine increased melanoma cell intercalation compared to pMBMECs with intact junctions. The newly generated brain-homing melanoma cell line YUMM1.1-BrM4 was used to reveal increased in vivo extravasation of melanoma cells across the BBB of barrier-compromised PECAM-1-deficient mice compared to controls. Taken together, our data indicate that preserving BBB integrity is an important measure to limit the formation of melanoma-brain metastasis

Planning of computer assisted maxillo-facial surgery and its clinical precision

Computer assisted surgery is a relatively new development in maxillo-facial surgery which has been in use approximately since the beginning of the Millennium. It can be applied pre-, intra- or postoperatively. Preoperatively it is utilized for instance for visualizing pathologies, virtual planning of fracture repair in 3D, simulation of fracture repair and planning of tumour resections and reconstruction. Modern computer technology also allows three-dimensional visualization and planning of orthognathic surgery. Some software products even integrate 3D portrait photographies of patients and permit a realistic simulation of the postoperative changes of facial soft tissue after osteotomies of the maxilla and the mandible. Ideally, these simulations reproduce the exact outcome of surgery. Intraoperatively the predominant use of computer assisted surgery is navigation guidance for a number of different interventions, mostly for primary or secondary trauma repair. Postoperatively computer assisted imaging helps to better evaluate and visualize surgical results. This thesis gives an overview of the evolution of primarily two topics: computer assisted trauma repair and realistic orthognathic soft tissue simulation. Today, the first subject has become a daily routine application. It improves surgical outcome and patient safety. Soft tissue simulation after orthognathic surgery however is not yet ready to be used routinely

Deep neck space abscesses of dental origin: the impact of Streptococcus group Milleri

In recent years, there has been rising interest in Streptococcus group Milleri (SM) because high mortality rates have been related to it. In case of deep neck infections (DNI), whatever the origin, mortality rates as high as 26 % were reported. But there are no data available for DNI with SM of purely dental origin. The aim of our article was to describe and analyse DNI of purely dental origin involving on one hand SM and on the other hand infections without presence of SM. We compared these two groups and statistically investigated if there were differences in clinical presentation (age, mouth opening, length of hospital stay, laboratory parameters) or clinical behaviour (re-operation, re-hospitalisation, secondary osteomyelitis, stay at intensive care, length of antibiotic treatment, presence of resistances against antibiotics, incapacity to work). For this, we retrospectively searched medical records of our institution for all purulent DNI treated from 2004 till 2012. We found 81 patients meeting all inclusion criteria. Thirty-four patients had involvement of SM, 47 did not. The only statistically significant difference between the SM group and the non-SM group was the length of incapacity to work. All other parameters were non-significant. Furthermore, there were no fatalities. In conclusion, the clinical importance of this article is that patients with deep neck abscesses of purely dental origin involving SM do not need more or different care when compared to all other DNI of dental origin

Image guided surgical navigation integrating "mirroring" computational planning based on intra-operative cone-beam CT imaging: a promising new approach for management of primary bilateral midfacial fractures

Cosmetic and functional re-establishment following primary or secondary treatment of comminuted and complex midfacial fractures remains a challenge for surgeons. Computer Assisted Surgery (CAS) has revolutionized the conceptualization and approach to these reconstructions and has become a reliable part of the surgical armamentarium. Computer aided design/modeling (CAD/CAM) software that allows "mirroring" planning coupled to navigation systems has dramatically improved surgical strategies in reconstructive surgery of the craniomaxillofacial skeleton, particularly with respect to the prediction of suitable symmetric bone repositioning. So far, however, use of this approach has been limited to unilateral cases, with a non-fractured contralateral side being considered the condition sine qua non for the application of such a technique and the "mirroring" planning being performed on pre-operative CT imaging. We report a case of complex primary reconstruction in a patient presenting with bilateral midfacial fractures, using complete intra-operative sequence processing with a navigation system integrating "mirroring" computational planning based on a mobile C-arm cone-beam computed tomography (CBCT) scan with a flat-panel detector. To the best of our knowledge, no similar cases have yet been reported involving the use of this sequencing method in the primary management of bilateral midfacial fracture reconstruction

Blood supply of the digital sheath

One hundred upper extremities from fresh human cadavers aged 20 to 80 years were injected with coloured latex or Indian ink and gelatin. Under the dissecting microscope two main and one occasional source of vascularization of the digital sheath were identified. Originating from the digitopalmar arches, from the proper palmar digital arteries and occasionally from the arcus palmaris superficialis, a complex arterial system supplies the various parts of the digital sheath. The best vascularized area is the floor of the sheath, while the pulleys and the palmar surface of the sheath are less well vascularized. These data may be of interest to those involved in reconstruction of the tendons of the digital flexor muscles

Précision des prédictions morphologiques en chirurgie orthognatique. Evaluation d'un procédé de fusion d'images 3D.

The CT/CBCT data allows for 3D reconstruction of skeletal and untextured soft tissue volume. 3D stereophotogrammetry technology has strongly improved the quality of facial soft tissue surface texture. The combination of these two technologies allows for an accurate and complete reconstruction. The 3D virtual head may be used for orthognatic surgical planning, virtual surgery, and morphological simulation obtained with a software dedicated to the fusion of 3D photogrammetric and radiological images

18F-DOPA PET/CT unravels malignant paraganglioma mimicking temporomandibular joint disorder

This report presents a 29-year-old patient with severe temporomandibular joint (TMJ) pain. Anamnesis and clinical examination led us to the diagnosis of TMJ disorder. He was also in control for a malignant paraganglioma originating from the right carotid body. After initial surgery 8.5 years ago and the removal of metastases 2 years ago he was deemed disease free. An (18)F-3,4-dihydroxyphenylalanine (DOPA) positron emission tomography (PET)/CT scan was obtained during follow-up 6 months before he was presented to our clinic. Suspicious of a connection between the actual pain and the tumour, we scrutinized these images. We found a tiny pathological tracer uptake in the right jugular foramen but no correlating finding in the matching CT. We repeated the DOPA PET/CT and found several metastases including the previously detected lesion. Further thin-slice CT and MRI showed a 5 mm paraganglioma located anteriorly to the jugular bulb within the jugular foramen. The lesion was in close relation to the Arnold's nerve, a branch of the vagus nerve which carries sensory information from the external tympanic membrane, external auditory canal and the external ear and explained the severe pain in our patient. He then underwent radiotherapy (45 Gy) during which the pain diminished considerably. In a variety of neuroendocrine tumours, including paraganglioma, DOPA PET/CT allows primary diagnosis, staging and restaging with a higher detection rate than conventional radiological imaging. Owing to low anatomical resolution however, high resolution contrast-enhanced CT and MRI are necessary to complete the investigations