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  • 1
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    Contact dermatitis 39 (1998), S. 0 
    ISSN: 1600-0536
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Copenhagen : Munksgaard International Publishers
    Skin research and technology 6 (2000), S. 0 
    ISSN: 1600-0846
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Background/aims: The capillary bed is recognized as the site where metabolic and nutrient processes occur for living tissues at all levels. The evaluation of this vital process is a major concern in microcirculation. Unlike traditional approaches that concentrated on the extreme local properties of this process, a more global analysis toward capillary ensembles is employed here, since capillaries work as a cooperative entirety. As a first step toward ensemble analysis, the static and planar geometric parameters are investigated. Parameters such as the capillary adjacency and size information are very important in predicting and analysing certain malfunctions in the microvascular bed.Methods/results: In order to achieve an objective and accurate analysis of these vital parameters, a computerized imaging system is proposed. Not only the number of capillaries and the capillary cross-sectional areas are important in describing the microvascular bed but the planar distribution pattern of the capillaries also carries valid information. This information, unique to the ensemble analysis, can be used to reveal, visualise and quantify the clustering of capillaries; and this information, according to the Krogh model, is fundamental in estimating the tissue oxygen supply. Two spatial models, the closest neighbor and triangulation methods, have been applied to the captured images of capillary ensembles. The closest neighbor technique generates a minimal distance map or displays a distribution, which depicts the local clustering of capillaries. The triangulation technique, on the other hand, generates a mutual distance map, which is a global description of the capillary positions. Triangulation methods have been evaluated but all except the Greedy triangulation method have been rejected due to lack of robustness and model weakness. Therefore, the capillaries are triangulated by the Greedy triangulation method, and the capillary distribution uniformity is defined as one minus the coefficient of variance of the edge lengths of the mutual distance map.Conclusions: A series of advanced image processing methods have been developed that efficiently extract the capillary position, size and distribution information from the images. These results facilitate the automatic counting of capillaries and the capillary size-related pathological analysis.
    Type of Medium: Electronic Resource
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  • 3
    ISSN: 1573-4838
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine , Technology
    Notes: The surface material and surface structure of orthopaedic implants are considered to be key parameters for clinical success. The goal of this study was to assess mechanical and histological aspects of uncoated and coated polymer plugs implanted transcortically into the femurs of rabbits for 6, 9, and 12 weeks. Cylindrical plugs (diameter 3×12 mm) made of ultra-high molecular weight polyethylene (UHMW-PE) or polyoxymethylene (POM) uncoated or coated with hydroxyapatite (HA) or titanium (Ti) were analysed in a push-out test to determine the interface shear strength. Compared to uncoated PE plugs, coated PE implants were always significantly better in interface strength (up to a factor of 20). HA-coated PE plugs reached their final shear strength after a shorter period of implantation (at 6 weeks) than Ti-coated plugs, but both finally yielded the same strength (at 12 weeks). With a thin Ti-plasma coating, the increase of interface strength of POM plugs was much smaller than the increase found in PE implants coated with a different technique. Microscopic analysis suggested that interface failure initially occurred between coating and bone. Histology revealed a stable, bony integration of all plug types. The increase in interface shear strength could not be explained by histological findings and must be caused mainly by the different surface structures of the implants or coatings.
    Type of Medium: Electronic Resource
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  • 4
    ISSN: 1573-4838
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine , Technology
    Notes: Abstract The biocompatibility and osseous integration of a new composite material made of polyurethane and a calcium silicophosphate ceramic was investigated in a loaded implant model in sheep and compared to that of commercially pure titanium. Six months after implantation, interfacial shear strength was higher between the titanium and bone than between the composite and bone. After 2 years, however, the shear strength was significantly higher in the composite group. Histologically, both implants were surrounded by bone and fibrous tissue and there were no signs of inflammation. Direct contact of bone on the composite surface increased significantly with time, whereas there was no time-dependent increase of bone contact on titanium. It can be concluded that the biocompatibility and osseous integration of the composite was very good in the loaded implant model used. It is therefore suggested that the new composite is a promising biomaterial for orthopaedic implants.
    Type of Medium: Electronic Resource
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  • 5
    ISSN: 1573-4838
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine , Technology
    Notes: Abstract The aim of this study was to evaluate the healing capacity of proximal anterior cruciate ligament (ACL) ruptures following primary repair with and without a bioresorbable augmentation. The ACL was transected at the femoral origin in the right knee joint of 24 sheep. The ACL was repaired in eight sheep (group B) without, and in eight sheep (group C) with a bioresorbable augmentation. Eight sheep without repair served as a control (group A). No immobilization was performed in any group. The sheep were sacrificed 13 weeks post-operatively. Macroscopically, all repaired ACLs were healed. The augmentation device was broken in all cases, but not completely degraded. In group A, none of the transected ACLs had healed. The anterior drawer under a load of 50 N was significantly lower in group C than in group A (p〈0.01). No significant difference was seen between groups B and A. The distribution and extent of chondromalacia (CM) in the operated knees depended on the type of operative treatment (p〈0.01). Groups A and B showed significantly more CM in the operated knee than in the non-operated knee (each p〈0.05). Proximal ACL ruptures can heal in sheep after both non-augmented and augmented ACL repair with free-functional rehabilitation. However, augmented repair leads to significantly better stability of the knee joint compared to transected controls and better limits the development of degenerative changes.
    Type of Medium: Electronic Resource
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  • 6
    ISSN: 1573-4838
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine , Technology
    Type of Medium: Electronic Resource
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  • 7
    Electronic Resource
    Electronic Resource
    Springer
    Langenbeck's archives of surgery 350 (1979), S. 83-93 
    ISSN: 1435-2451
    Keywords: Abdominal wall ; Hernia ; Carbon cloth ; Alloplastic replacement
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Zusammenfassung Kohlenstoffgewebe ist ein Material, das sich als Ersatz von Stütz- und Bindegewebe beim Menschen wegen der guten physikalischen und biologischen Eigenschaften anbietet. An 20 Kaninchen wurde ein gewebtes Tuch aus Kohlenstoffasern zur Überbrückung eines Bauchwanddefektes implantiert. 10 weitere Tiere mit operativ gesetzten Bauchwanddefekten dienten als Kontrollgruppe. Das Material heilte gut ein, Hernien traten bei den implantierten Tieren nicht auf. Histologisch konnte gezeigt werden, daß nach 3 Monaten ein kollagenes Fasergewebe in das Kohlenstofftuch eingewachsen war und sich so ein fester, belastungsfähiger Bauchdeckenersatz gebildet hatte. Eine Zugfestigkeitsprüfung zeigte eine sehr gute Verankerung im natürlichen Gewebe und eine hohe Festigkeit der neuen Bauchdecken.
    Notes: Summary Carbon cloth is a new biomaterial which is suitable for the replacement of ligaments and connective tissues, because of its biological and physical properties. In 30 rabbits a defect was cut into the abdominal wall. In 20 the defect was covered by an implanted carbon cloth. The other 10 animals were used as controls. After implantation wound healing was excellent. No herniation could be observed in the group with the implants. After 3 months histological examinations revealed the ingrowth of collagen fibres into the carbon cloth. It had become a strong and resilient abdominal wall replacement. A physical-strength test showed stability of the newly formed abdominal wall with good anchorage to normal tissue.
    Type of Medium: Electronic Resource
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  • 8
    Electronic Resource
    Electronic Resource
    Springer
    Calcified tissue international 60 (1997), S. 194 -199 
    ISSN: 1432-0827
    Keywords: Key Words: Fracture repair — Biomechanics — Quantitative computed tomography — Histology — Radiography.
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Notes: Abstract. An experimental fracture model was used to assess bone mineral density at the fracture site by peripheral computed tomography and to compare the model with biomechanical, histological, and radiographic methods for the quantification of the fracture repair process. Transverse osteotomies in the mid-diaphysis of 28 tibia of sheep were externally fixed and mineral densities, cross-sectional areas, flexural rigidities, tissue composition, and projected callus area were calculated after 9 weeks of healing time. BMD measured by pQCT was strongly correlated with histologically determined percentages of mineralized tissue in the osteotomy gap (R 2= 0.71) and in the periosteal callus (R 2= 0.62). The percentage of mineralized tissue in the osteotomy gap was the best predictor of the flexural rigidity of the tibiae (R 2= 0.74). Because of high correlations with the histological findings, the volumetric BMD at the level of the osteotomy gap was also strongly correlated with the biomechanical findings (R 2= 0.70). Neither the cross-sectional area in pQCT nor the projected callus area in plane film radiography were positively correlated to the flexural rigidity of the tibiae. Quantitative computed tomography proved to be a successful estimator for the prediction of the mechanical stability of healing bones. The noninvasive procedure is a reliable tool for the quantification of the fracture repair process in experimental studies and may be useful for treatment decisions in particular clinical situations.
    Type of Medium: Electronic Resource
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  • 9
    ISSN: 1432-0932
    Keywords: Spinal biomechanics Stiffness ; Motion ; Calf ; In vitro testing
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract The availability of human cadaveric spine specimens for in vitro tests is limited and the risk of infection is now of vital concern. As an alternative or supplement, calf spines have been used as models for human spines, in particular to evaluate spinal implants. However, neither qualitative nor quantitative biomechanical data on calf spines are available for comparison with data on human specimens. The purpose of this study was to determine the fundamental biomechanical properties of calf spines and to compare them with existing data from human specimens. Range of motion, neutral zone, and stiffness properties of thoracolumbar calf spines (T6-L6) were determined under pure moment loading in flexion and extension, axial left/right rotation and right/left lateral bending. Biomechanical similarities were observed between the calf and reported human data, most notably in axial rotation and lateral bending. Range of motion in the lumbar spine in flexion and extension was somewhat less in the calf than that typically reported for the human, though still within the range. These results suggest that the calf spine can be considered on a limited basis as a model for the human spine in certain in vitro tests.
    Type of Medium: Electronic Resource
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  • 10
    ISSN: 1432-0932
    Keywords: Key words Posterior instrumentation ; Occipito-cervical spine ; Biomechanical testing, in vitro
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Posterior instrumentation of the occipito-cervical spine has become an established procedure in a variety of indications. The use of rod-screw systems improved posterior instrumentation as it allows optimal screw positioning adapted to the individual anatomic situation. However, there are still some drawbacks concerning the different implant designs. Therefore, a new modular rod-screw implant system has been developed to overcome some of the drawbacks of established systems. The aim of this study was to evaluate whether posterior internal fixation of the occipito-cervical spine with the new implant system improves primary biomechanical stability. Three different internal fixation systems were compared in this study: the CerviFix System, the Olerud Cervical Rod Spinal System and the newly developed Neon Occipito Cervical System. Eight human cervical spine C0/C5 specimens were instrumented from C0 to C4 with occipital fixation, transarticular screws in C1/C2 and lateral mass or pedicle screws in C3 and C4. The specimens were tested in flexion/extension, axial rotation, and lateral bending using pure moments of ± 2.5 Nm without axial preload. After testing the intact spine, the different instrumentations were tested after destabilising C0/C2 and C3/C4. Primary stability was significantly increased, in all load cases, with the new modular implant system compared to the other implant systems. Pedicle screw instrumentation tended to be more stable compared to lateral mass screws; nevertheless, significant differences were observed only for lateral bending. As the experimental design precluded any cyclic testing, the data represent only the primary stability of the implants. In summary, this study showed that posterior instrumentation of the cervical spine using the new Neon Occipito Cervical System improves primary biomechanical stability compared to the CerviFix System and the Olerud Cervical Rod Spinal System.
    Type of Medium: Electronic Resource
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