Fractures of the paranasal sinuses often require surgical intervention. Persisting bone defects lead to permanent visible deformities of the facial contours. Bone substitutes for reconstruction of ...defects with simultaneous induction of new bone formation are not commercially available for the paranasal sinus. New materials are urgently needed and have to be tested in their future area of application. For this purpose critical size defect models for the paranasal sinus have to be developed. A ≥2.4 cm large bilateral circular defect was created in the anterior wall of the maxillary sinus in six sheep via an extraoral approach. The defect was filled with two types of an osteoconductive titanium scaffold (empty scaffold vs. scaffold filled with a calcium phosphate bone cement paste) or covered with a titanium mesh either. Sheep were euthanized after four months. All animals performed well, no postoperative complications occured. Meshes and scaffolds were safely covered with soft tissue at the end of the study. The initial defect size of ≥2.4 cm only shrunk minimally during the investigation period confirming a critical size defect. No ingrowth of bone into any of the scaffolds was observed. The anterior wall of the maxillary sinus is a region with low complication rate for performing critical size defect experiments in sheep. We recommend this region for experiments with future scaffold materials whose intended use is not only limited to the paranasal sinus, as the defect is challenging even for bone graft substitutes with proven osteoconductivity.
Graphical abstract
Nanoporous aluminum oxide membranes were prepared by anodic oxidation of aluminum for application as novel cell culture substrates. Self-supporting as well as mechanically stabilized nanoporous ...membranes were produced from aluminum plates and micro-imprinted aluminum foils, respectively. Membranes of two different pore sizes (70 and 260
nm) were selected to investigate cellular interactions with such nanoporous substrates using cells of hepatoma cell line HepG2. The membranes express excellent cell-growth conditions. As shown by scanning electron microscopy investigations, the cells could easily adhere to the membranes and proliferate during a 4
day cell culture period. The cells exhibit normal morphology and were able to penetrate into pores with a diameter of 260
nm by small extensions (filopodia). On mechanically stabilized aluminum oxide membranes it was observed that the cells even adhere to the walls of the small cavities. It was demonstrated experimentally that the nanoporous aluminum oxide membranes are well suited as substrates in cell culture model systems for metabolic, pharmacological/toxicological research, tissue engineering and studies on pathogens as well as bioartificial liver systems.
Large skull-base meningiomas are difficult to treat due to their proximity or adherence to critical structures. We analyzed the long-term results of patients with skull-base meningiomas treated by a ...new approach with high-precision fractionated stereotactic radiotherapy.
One hundred eighty-nine patients with benign meningiomas were treated with conformal fractionated stereotactic radiotherapy between 1985 and 1998. Patients were undergoing a course of radiotherapy either as primary treatment, following subtotal resection, or for recurrent disease. The median target volume was 52.5 mL (range, 5.2 to 370 mL). The mean radiation dose was 56.8 Gy (+/- 4.4 Gy). Follow-up examinations, including magnetic resonance imaging, were performed at 6-month intervals thereafter.
The median follow-up period was 35 months (range, 3 months to 12 years). Overall actuarial survival for patients with World Health Organization (WHO) grade I meningiomas was 97% after 5 years and 96% after 10 years. Local tumor failure was observed in three of 180 patients with WHO grade I tumors and was significantly higher in two of nine patients with WHO grade II tumors. A volume reduction of more than 50% was observed in 26 patients (14%). Preexisting cranial nerve symptoms resolved completely in 28% of the patients. Clinically significant treatment-induced toxicity was seen in 1.6% of the patients. No treatment-related deaths occurred.
The results of this study demonstrate that fractionated stereotactic radiotherapy is safe and effective in the therapy of subtotally resected or unresectable meningiomas. The overall morbidity and incidence subacute and late side effects of this conformal radiotherapy approach were low.
Lipopolysaccharide (LPS), or endotoxin, is the major mediator of septic shock, a serious complication of Gram‐negative bacterial infections in humans. Molecules that bind LPS and neutralize its ...biological effects or enhance its clearance could have important clinical applications. Limulus anti‐LPS factor (LALF) binds LPS tightly, and, in animal models, reduces mortality when administered before or after LPS challenge or bacterial infection. Here we present the high resolution structure of a recombinant LALF. It has a single domain consisting of three alpha‐helices packed against a four‐stranded beta‐sheet. The wedge‐shaped molecule has a striking charge distribution and amphipathicity that suggest how it can insert into membranes. The binding site for LPS probably involves an extended amphipathic loop, and we propose that two mammalian LPS‐binding proteins will have a similar loop. The amphipathic loop structure may be used in the design of molecules with therapeutic properties against septic shock.
Even today, treatment of Stage III NSCLC still poses a serious challenge. So far, surgical resection is the treatment of choice. Patients whose tumour is not resectable or who are unfit to undergo ...surgery are usually referred to a combined radio-chemotherapy. However, combined radio-chemotherapeutic treatment is also associated with sometimes marked side effects but has been shown to be more efficient than radiation therapy alone. Nevertheless, there is a significant subset of patients whose overall condition does not permit administration of chemotherapy in a combined-modality treatment. It could be demonstrated though, that NSCLCs often exhibit over-expression of EGF-receptors hence providing an excellent target for the monoclonal EGFR-antagonist cetuximab (Erbitux) which has already been shown to be effective in colorectal as well as head-and-neck tumours with comparatively mild side-effects.
The NEAR trial is a prospective phase II feasibility study combining a monoclonal EGF-receptor antibody with loco-regional irradiation in patients with stage III NSCLC. This trial aims at testing the combination's efficacy and rate of development of distant metastases with an accrual of 30 patients. Patients receive weekly infusions of cetuximab (Erbitux) plus loco-regional radiation therapy as intensity-modulated radiation therapy. After conclusion of radiation treatment patients continue to receive weekly cetuximab for 13 more cycles.
The primary objective of the NEAR trial is to evaluate toxicities and feasibility of the combined treatment with cetuximab (Erbitux) and IMRT loco-regional irradiation. Secondary objectives are remission rates, 3-year-survival and local/systemic progression-free survival.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
In this study, two different extraction approaches were compared in order to evaluate the cytotoxicity of 7 different acrylic bone cements, mainly developed for spinal applications, to osteoblastic ...cells. Firstly, a static extraction was carried out continuously over 24h, a method widely used in literature. Secondly, a quasi-dynamic extraction method that allowed the investigation of time-dependent cytotoxic effects of curing acrylic bone cements to cells was introduced. In both cases the extraction of the cements was started at a very early stage of the polymerization process to simulate the conditions during clinical application. Data obtained by the quasi-dynamic extraction method suggest that the cytotoxicity of the setting materials mainly originates from the release of toxic components during the first hour of the polymerization reaction. It was also shown that a static extraction over 24h generally represents this initial stage of the curing process. Furthermore, compared to the static extraction, time-dependent cytotoxicity profiles could be detected using the quasi-dynamic extraction method. Specifically, a modification of commercial Osteopal®V with castor oil as a plasticizer as well as a customized cement formulation showed clear differences in cytotoxic behavior compared to the other materials during the setting process. In addition, it was observed that unreacted monomer released from the castor oil modified cement was not the main component affecting the toxicity of the material extracts. The quasi-dynamic extraction method is a useful tool to get deeper insight into the cytotoxic potential of curing acrylic bone cements under relevant biological conditions, allowing systematic optimization of materials under development.
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•Cytotoxicity of low-modulus PMMA bone cements was evaluated using material extracts.•A quasi-dynamic extraction method was established.•Cytotoxicity of curing acrylic bone cements is a time dependent variable.•Modification of PMMA bone cements can alter their cytotoxic potential.
Abstract
A new experimental test facility was designed to test vapor compression chillers of up to 145.9 refrigeration tons (approximately 513 kW). To implement such a large-capacity test facility in ...a university laboratory research environment, the system design is based on regenerative shell and tube heat exchangers. The capacity load on the chiller can be controlled via a bypass valve that allows a flow change over the internal heat exchangers. In addition to the internal sensors of the chiller, a variety of sensors in the system ensures a detailed recording of data as well as an automation of the test procedure.
The test facility is constructed and commissioned to execute the performance according the AHRI Standard 550/590. The chiller has been tested in full load and part load rating conditions to achieve a characteristic performance line of the machine. Recorded data is averaged and evaluated according to the requirements of the AHRI standard. The results of the baseline testing and the data processing are presented in this paper. A detailed analysis of the outcomes allows a comparison with the manufacturer rated efficiency values.
Finally, the potential instabilities of the test systems that caused problems during the test runs and their reasons are discussed, as well as possibilities to overcome them. The given ability of the test facility for a rapid change between different load conditions allows the arrangement of test cycles to investigate the performance degradation of the twin-screw chiller over time.
The treatment of early-stage lung cancers is a primary domain of thoracic surgery, leading to persuasive results. In patients with medical contraindications, radiotherapy is an alternative, although ...with considerably worse outcome. Radiotherapy is associated with the risk of severe acute side effects and a permanent decrease of lung function. By the introduction of an extracranial stereotactic treatment technique, the amount of normal tissue in the high-dose region can be reduced, allowing the performance of single-dose treatment with high, biologically effective doses.
Between October 1998 and May 2001, 10 patients with histologically confirmed Stage I non–small-cell lung cancer were treated with stereotactic single-dose radiotherapy. A self-developed stereotactic frame was used for patient positioning and navigation. Total doses applied ranged from 19 to 26 Gy. After treatment, regular CT-based follow-up was performed.
During a median follow-up period of 14.9 months, the tumors in 8 of 10 patients were locally controlled. The actuarial overall survival was 80% and 64%, respectively, 12 and 24 months after therapy. Actuarial local recurrence–free survival reached 88.9% and 71.1%, respectively. Therapy-related perifocal normal-tissue reaction occurred in 70% of all treated patients, although no major clinical symptoms were seen. In 5 patients, systemic metastases were found during follow-up; 1 patient developed suspect mediastinal lymph nodes.
Stereotactic single-fraction radiotherapy is a feasible, safe, and effective procedure for the treatment of Stage I non–small-cell lung cancer. It promises high local control with a reduced overall treatment time. However, further investigation in a larger patient collective with extended follow-up is necessary.
Abstract
Enabling autonomous and Beyond Visual Line of Sight (BVLOS) operation of Unmanned Aerial Vehicles (UAVs) in the Very Low Level (VLL) airspace requires further advancement of technologies ...such as sensing the environment or secure and reliable communication. This paper addresses these challenges by presenting solutions developed within the project Airborne Data Collection on Resilient System Architectures (ADACORSA). Here, findings from cross-sectional areas such as the automotive industry are being further enhanced to fulfill the demands of aviation, in particular for use in the UAV domain. The developed technologies include an advanced Ethernet-based deterministic network for reliable onboard communication, a multi-sensor architecture for sensing the spatial environment as well as a multi-link communication gateway that provides reliable communication to the ground and a secure handover architecture.
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