Development of an opto-electronic positioning device for serial direct digital images of oral structures.

The aim of this study was to develop and test in vitro an opto-electronic positioning device for serial direct digital images of oral structures, i.e. to associate direct digital imaging with the principles of computer-aided surgery.

Frameless computer-aided surgery system for revision endoscopic sinus surgery.

To increase the intraoperative safety factor and to acquire anatomic assistance during revision endoscopic sinus surgery (RESS), we used an optical computer-aided surgery (CAS) system that we developed collaboratively in Bern, Switzerland. During 1 year, 25 RESSs were performed with CAS: recurrent polyposis (n = 20), recurrent frontal recess stenosis (n = 3), and recurrent frontal recess stenosis with mucocele (n = 2). These patients were compared with a control group of 10 patients undergoing RESS without CAS.

On array design for matched-field processing.

Conventional plane-wave beamforming array design guidelines are motivated by the desire to obtain particular beampattern characteristics, such as main lobe width and side lobe levels. These design guidelines are appropriate for arrays employed for beamforming, where a plane-wave signal model is utilized to derive both the array design parameters and the beamforming algorithm. However, matched-field processing utilizes full-field acoustic propagation models to exploit the complexities of ocean acoustic propagation.

A new approach to computer-aided spine surgery: fluoroscopy-based surgical navigation.

A new computer-based navigation system for spinal surgery has been designed. This was achieved by combining intraoperative fluoroscopy-based imaging using conventional C-arm technology with free-hand surgical navigation principles. Modules were developed to automate digital X-ray image registration.

A comparative biomechanical investigation of anterior lumbar interbody cages: central and bilateral approaches.

Background: Some biomechanical studies have been performed to evaluate the stabilization provided by interbody cages, but there are virtually no comparative data for the different designs. Furthermore, most investigators have used animal models, which may have led to different results due to morphological variation in the end plates and articular facets. The objectives of the current study were to evaluate whether two different anterior cage designs (BAK and SynCage) performed differently with respect to immediate stabilization of the spine, whether the cages stabilized the spine significantly compared with its intact condition, and whether the addition of supplementary translaminar screw fixation further stabilized the spine.

Increased expression of GLUT-4 and hexokinase in rat epitrochlearis muscles exposed to AICAR in vitro.

Exercise acutely stimulates muscle glucose transport and also brings about an adaptive increase in the capacity of muscle for glucose uptake by inducing increases in GLUT-4 and hexokinase.(1) Recent studies have provided evidence that activation of AMP protein kinase (AMPK) is involved in the stimulation of glucose transport by exercise. The purpose of this study was to determine whether activation of AMPK is also involved in mediating the adaptive increases in GLUT-4 and hexokinase.

Load-sharing characteristics of stabilized lumbar spine segments.

Study Design: Load sharing in stabilized spinal segments was evaluated using sequential injury and stabilization with a posterior instrumentation system under an in vitro flexibility protocol.

Objective: To analyze the partitioning of applied loads between anatomic and implanted structures of lumbar functional spinal units stabilized with a posterior instrumentation system. To identify surgical indications for which the risk of fixator breakage in vivo is high.

Three-dimensional measurement of cemented femoral stem stability: an in vitro cadaver study.

Objective: To compare the in vitro stability of two cemented hip stem designs: Stem I was a collarless, double-tapered, highly polished implant; Stem II had a collar and matt finish.

Background: Stability of the femoral component of a hip implant is important for its long-term clinical success. Excessive migration or cyclic motion can increase the risk of early implant failure.

The "Bernese" frameless optical computer aided surgery system.

Objective: We report on two years of clinical experience with a frameless Computer Aided Surgery system developed in Bern, Switzerland.

Material And Methods: Our navigation system is based on a preoperative computer-tomography (CT) scan (without markers) and an intraoperative optical tracking of head movements and of the surgical instruments. Using landmark and surface-based registration, the skull can be accurately correlated to the CT images.

A pilot study on computer-assisted optimal contouring of orthopedic fixation devices.

Bending and shaping of longitudinal orthopedic fixation devices like rods and plates is often a difficult and time-consuming process to perform during surgery under sterile conditions. This study presents a novel device for implant contouring and introduces two strategies to obtain parameters necessary for the bending process. The first strategy is based on surgical navigation techniques as established within the framework of computer-assisted orthopedic surgery.

Fluoroscopy as an imaging means for computer-assisted surgical navigation.

Objective: Intraoperative fluoroscopy is a valuable tool for visualizing underlying bone and surgical tool positions in orthopedic procedures. Disadvantages of this technology include the need for continued radiation exposure for visual control, and cumbersome means of alignment. The purpose of this article was to highlight a new concept for a computer-assisted freehand navigation system that uses single intraoperatively acquired fluoroscopic images as a basis for real-time navigation of surgical tools.

[Surgery of the skull base and paranasal sinuses assisted by a computerized navigation system without external orientation support].

Objective: To present a new concept in computer-assisted surgery for the base of the skull and paranasal sinuses using a frameless navigation system.

Method And Materials: This system is based on computer tomography images, which are displayed online on a workstation monitor. Using specially mounted infrared instruments, the patient's anatomic landmarks are visualized on the monitor.

Changes in glucose transport and protein kinase Cbeta(2) in rat skeletal muscle induced by hyperglycaemia.

Aims/hypothesis: We have previously reported that hyperglycaemia activates glucose transport in skeletal muscle by a Ca(2+)-dependent pathway, which is distinct from the insulin-signalling pathway. The aim of this study was to explain the signalling mechanism by which hyperglycaemia autoregulates glucose transport in skeletal muscle.

Methods: Isolated rat soleus muscle was incubated in the presence of various concentrations of glucose or 3-O-methylglucose and protein kinase C and phospholipase C inhibitors.

Interface shear strength of titanium implants with a sandblasted and acid-etched surface: a biomechanical study in the maxilla of miniature pigs.

The purpose of the present study was to evaluate the interface shear strength of unloaded titanium implants with a sandblasted and acid-etched (SLA) surface in the maxilla of miniature pigs. The two best documented surfaces in implant dentistry, the machined and the titanium plasma-sprayed (TPS) surfaces served as controls. After 4, 8, and 12 weeks of healing, removal torque testing was performed to evaluate the interface shear strength of each implant type.

Decreased insulin-stimulated GLUT-4 translocation in glycogen-supercompensated muscles of exercised rats.

It was recently found that the effect of an exercise-induced increase in muscle GLUT-4 on insulin-stimulated glucose transport is masked by a decreased responsiveness to insulin in glycogen-supercompensated muscle. We evaluated the role of hexosamines in this decrease in insulin responsiveness and found that UDP-N-acetyl hexosamine concentrations were not higher in glycogen-supercompensated muscles than in control muscles with a low glycogen content. We determined whether the smaller increase in glucose transport is due to translocation of fewer GLUT-4 to the cell surface with the 2-N-4-(1-azi-2,2,2-trifluroethyl)-benzoyl-1, 3-bis(D-mannose-4-yloxy)-2-propylamine (ATB-[2-3H]BMPA) photolabeling technique.

Biomechanical properties of sterilized human auditory ossicles.

Bone allograft material is treated with sterilization methods to prevent the transmission of diseases from the donor to the recipient. The effect of some of these treatments on the integrity of the bone is unknown. This study was performed to evaluate the effect of several sterilization methods on the mechanical behaviour of human middle ear bones.

[The method of computer-assisted orthopedic surgery based on two-dimensional fluoroscopy: the principles of action].

Surgical instruments play a major role in orthopedic surgery; usually they are controlled visually at the operation. In certain situations additional device to control instrument is needed. The aim of this paper is to present theoretical foundations, create prototype and give initial assessment of computer assisted orthopedic surgery system.

Insulin resistance of muscle glucose transport in male and female rats fed a high-sucrose diet.

It has been reported that, unlike high-fat diets, high-sucrose diets cause insulin resistance in the absence of an increase in visceral fat and that the insulin resistance develops only in male rats. This study was done to 1) determine if isolated muscles of rats fed a high-sucrose diet are resistant to stimulation of glucose transport when studied in vitro and 2) obtain information regarding how the effects of high-sucrose and high-fat diets on muscle insulin resistance differ. We found that, compared with rat chow, semipurified high-sucrose and high-starch diets both caused increased visceral fat accumulation and insulin resistance of skeletal muscle glucose transport.

Mechanical tensile properties of the quadriceps tendon and patellar ligament in young adults.

We analyzed mechanical tensile properties of 16 10-mm wide, full-thickness central parts of quadriceps tendons and patellar ligaments from paired knees of eight male donors (mean age, 24.9 years). Uniaxial tensile testing was performed in a servohydraulic materials testing machine at an extension rate of 1 mm/sec.

[Computer-assisted surgical navigation with a dynamic mobile framework for the nasal fossae, sinuses and base of the skull].

Surgery of the skull base and of the paranasal sinuses is often difficult because of the complex anatomy and the delicate structures; serious complications (loss of vision, cerebral lesion) have been reported. To improve the safety of such operations, computer-assisted navigation surgery is increasingly being put to use. We introduce the system which was developed in Berne.

The role of supplemental translaminar screws in anterior lumbar interbody fixation: a biomechanical study.

The immediate stabilization provided by anterior interbody cage fixation is often questioned. Therefore, the role of supplementary posterior fixation, particularly minimally invasive techniques such as translaminar screws, is relevant. The purpose of this biomechanical study was to determine the immediate three-dimensional flexibility of the lumbar spine, using six human cadaveric functional spinal units, in four different conditions: (1) intact, (2) fixed with translaminar screws (TLS), (3) instrumented with anterior interbody cage insertion with the BAK system and (4) instrumented with BAK cage with additional TLS fixation.

Removal torque values of titanium implants in the maxilla of miniature pigs.

The purpose of this study was to compare side-by-side two different titanium screw-type implants in the maxillae of miniature pigs. The test implants had a machined and acid-etched surface (Osseotite) whereas the control implants were sandblasted and acid-etched (SLA). After 4, 8, and 12 weeks of healing, removal torque testing was performed to evaluate the shear strength of the bone-implant interface for both implant types.

Removal of adenosine decreases the responsiveness of muscle glucose transport to insulin and contractions.

Adenosine in the extracellular space modulates stimulated glucose transport in striated muscle. In the heart and in adipocytes, adenosine potentiates insulin-stimulated glucose transport. There is controversy regarding the effect of adenosine in skeletal muscle, with reports of both an inhibitory effect and no effect, on insulin-stimulated glucose transport.

Increased GLUT-4 translocation mediates enhanced insulin sensitivity of muscle glucose transport after exercise.

The purpose of this study was to determine whether the increase in insulin sensitivity of skeletal muscle glucose transport induced by a single bout of exercise is mediated by enhanced translocation of the GLUT-4 glucose transporter to the cell surface. The rate of 3-O-[3H]methyl-D-glucose transport stimulated by a submaximally effective concentration of insulin (30 microU/ml) was approximately twofold greater in the muscles studied 3.5 h after exercise than in those of the sedentary controls (0.