Biological responses to individualized small titanium implants for the treatment of focal full-thickness knee cartilage defects in a sheep model.

BACKGROUND: The present study aimed to evaluate the functional, radiological and histological outcome of a customized focal implant for the treatment of focal full-thickness cartilage defects in sheep. METHODS: The study used magnetic resonance imaging data as the basis for construction of the titanium implant using a three-dimensional printing technique. This was then placed on the medial condyle of the knee joint in eight sheep and left in place in vivo over a period of six months. Following euthanasia, the local biological response was analyzed using micro-computed tomography, light microscopy and histological evaluation (International Cartilage Repair Society (ICRS) score). The variables were analyzed using a generalized linear mixed model. Odds ratios were given with 95% confidence intervals. RESULTS: The osseointegration rate was 62.1% (SD 3.9%). All implants were prone to the neighboring cartilage bed (4.4-1096.1 µm). Using the IRCS score, the elements 'surface', 'matrix', 'cell distribution' and 'cell population' all showed pathological changes on the operated side, although these did not correlate with implant elevation. On average, a difference of 0.7 mm (±2 mm) was found between the digitally planned implant and the real implant. CONCLUSIONS: As a result of imprecise segmentation and difficult preparation conditions at the prosthesis bed, as well as changes at the surface of the implant over the operational lifetime of the prosthesis, it must be stated that the approach implemented here of using a customized implant for the treatment of focal full-thickness cartilage defects at the knee did not meet our expectations.

Risk of long-term anticoagulation under sustained severe arterial hypertension: A translational study comparing warfarin and the new oral anticoagulant apixaban.

New oral anticoagulants for the prevention of stroke and systemic embolism in patients with atrial fibrillation have recently been introduced. In this translational study, we explored the risk of long-term anticoagulation on intracerebral hemorrhage under sustained severe arterial hypertension. We initiated anticoagulation with warfarin or apixaban in spontaneously hypertensive rats prone to develop severe hypertension and subsequent intracerebral bleeding complications. A non-anticoagulated group served as control. During an 11-week-study period, blood pressure, anticoagulation parameters, and clinical status were determined regularly. The incidence of histopathologically proven intracerebral hemorrhage was defined as the primary endpoint. Both warfarin and apixaban anticoagulation was fairly stable during the study period, and all rats developed severe hypertension. Intracerebral hemorrhage was determined in 29% (4/14) of warfarin rats and in 10% (1/10) of apixaban rats. Controls did not show cerebral bleeding complications (chi-square not significant). Mortality rate at study termination was 33% (2/6) in controls, 43% (6/14) in the warfarin group, and 60% (6/10) in the apixaban group. Animals died from extracerebral complications in most cases. Our study describes an experimental intracerebral hemorrhage model in the context of sustained hypertension and long-term anticoagulation. Extracerebral bleeding complications occurred more often in warfarin-treated animals compared with apixaban and control rats.

Experimental subacute spinal cord compression: correlation of serial S100B and NSE serum measurements, histopathological changes, and outcome.

OBJECTIVE: To correlate serial measurements of serum S100B and neuron-specific enolase (NSE) with histopathological changes of the spinal cord and to assess their prognostic significance in a set-up of experimental spinal cord compression. METHODS: The thoracic cords of 22 rabbits were increasingly compressed and decompressed once paresis had developed. After decompression, outcome was rated as favorable or unfavorable. Following sacrifice of the animals, the cord was analyzed microscopically and morphometrically. Serum S100B and NSE were measured daily, and levels were correlated with initial degree of paresis, outcome after decompression, and histopathological changes of the cord. RESULTS: Regardless of the initial degree of paresis, animals with favorable outcome had significantly higher cell counts than animals with unfavorable outcome. The time course of S100B values following decompression was correlated with outcome. Animals with favorable outcome had either always normal levels or levels that were initially increased but normalized within 2 days. The values of animals with unfavorable outcome were elevated throughout (P<0.0001). No correlation was found between NSE levels and outcome. CONCLUSIONS: The initial degree of paresis is not a prognostic factor to predict outcome. Despite timely decompression, pronounced structural lesions of the cord may develop, resulting in an unfavorable outcome. In cases with favorable outcome, sufficient tissue is preserved to maintain function regardless of the initial extent of paresis. This different reaction of the cord may be followed indirectly with serial measurements of S100B serum levels. Thus, S100B is a reliable biochemical marker allowing for prediction of outcome. NSE does not have this prognostic significance.

Dual-energy computed tomography for the detection of late enhancement in reperfused chronic infarction: a comparison to magnetic resonance imaging and histopathology in a porcine model.

OBJECTIVES: To evaluate the performance of late enhancement dual-energy CT (LE-DECT) for the detection of infarcted myocardium as compared with 1.5-T late enhancement magnetic resonance imaging (LE-MRI) in a porcine model of reperfused chronic myocardial infarction (MI), using histopathology as standard of reference. MATERIALS AND METHODS: In 8 healthy minipigs, MI was induced by 30-minute balloon occlusion of the left anterior descending coronary artery. Sixty-one ± 4 days after left anterior descending coronary artery occlusion, LE-DECT was performed 5, 10, and 15 minutes subsequent to contrast material injection. Therefore, a dual-source CT scanner (Somatom Definition, Siemens Healthcare, Forchheim, Germany) was used in dual-energy mode with the following protocol: tube potential/current 140 kV/95 mAs on tube A and 100 kV/165 mAs on tube B, collimation 2 × 32 × 0.6 mm, 1.5 mL/kg contrast material injected at 3 to 4 mL/s. Myocardial iodine distribution was calculated from the dual-energy data and superimposed on the gray scale multiplanar reformats of the heart in short-axis view. Fifty ± 12 minutes after LE-DECT imaging, 1.5-T LE-MRI (Magnetom Avanto, Siemens Healthcare, Forchheim, Germany) was performed 10 minutes successive to injection of contrast material using phase-sensitive inversion recovery sequences. For all pigs investigated, 2,3,5-triphenyltetrazolium chloride staining and histopathology of stained-tissue samples were acquired. Two experienced radiologists assessed all imaging studies in a random manner and were blinded to the results of the other techniques for the presence of late enhancement (LE). The American Heart Association 17-segment model was used to compare the results of LE-DECT, 100 kV grayscale LE images, LE-MRI, and histopathology. Size of MI was calculated for histopathological findings, LE-MRI, LE-DECT, and 100 kV grayscale LE images 10 minutes after contrast agent injection. Agreement between infarct size assessed with imaging modalities and histopathology was evaluated with Bland-Altman analysis. RESULTS: Of the 136 myocardial segments in 8 minipigs, histopathology found MI in 27 segments. Diagnostic per-segment sensitivities and specificities for 100 kV grayscale LE images, LE-DECT images, and MR images obtained 10 minutes after contrast agent injection for both the readers were 0.62, 0.77, 0.79 and 0.97, 0.92, 0.94, respectively. Although sensitivities were higher for LE-DECT and LE-MRI than for 100 kV grayscale images, no statistically significant difference for the diagnostic accuracies of 100 kV grayscale LE images, LE-DECT images, and MR images (0.9, 0.89, 0.9) existed 10 minutes successive to contrast agent injection (all P > 0.05). Infarct size for LE-MRI, LE-DECT, and 100 kV grayscale LE images correlated well with histopathological findings (r = 0.97, 0.96, and 0.94; all P < 0.01). CONCLUSIONS: This feasibility study shows a high accuracy and a good correlation of LE-DECT and LE-MRI to histopathology for the detection of LE in a porcine model of reperfused chronic MI.

[Experimental studies on the wounding capacity of recently developed shuriken/throwing stars and their legal categorization--an interdisciplinary view]. / Experimentelle Studien zur Gefährlichkeit von neu entwickelten Shuriken/Wurfsternen und deren rechtliche Einordnung-- eine interdisziplinäre Darstellung.

Shuriken/throwing stars are traditional Japanese weapons for close combat situations. They vary greatly in shape and mode of action. Due to their wounding capacity traditional shuriken made of steel were prohibited in Germany in the 1980's. In the present study three recently developed types of shuriken were examined to determine their wounding capacity. Type 1 was made of plastic, whereas type 2 was a so-called cyclone shuriken equipped with three knives protruding from a discoidal center due to centrifugal force during the flight. Type 3 consisted of three traditional metal shuriken with blunt edges and peaks produced for decorative purposes. Experiments using pig carcasses were carried out for types 1 and 2. An experiment using human skin was performed with type 3 shuriken. An experienced thrower performed throws from a distance of 1, 2, 3, and 4 m with the shuriken made of plastic. For the cyclone shuriken a distance of 4 m was chosen to ensure the unfolding of the shuriken during flight. Type 3 shuriken were tested using a distance of 2 m. Penetration depths of the shuriken made of plastic reached up to 8 mm in pig skin. The experiment with the cyclone shuriken revealed a penetration depth of up to 2.5 cm cutting through the entire abdominal tissue and opening up an intestinal loop whereas type 3 shuriken yielded maximal penetration depths between 0.9 and 2.3 cm. This study indicates that all three types of shuriken may inflict lethal wounds upon opponents in close combat. The findings of this study should promote a public discussion whether the ban on traditional shuriken should be extended to the recently developed types.

Growth hormone supplementation increased latency to tumourigenesis in Atm-deficient mice.

Growth hormone (GH) is important for cell growth and differentiation, has multiple effects on lymphoid tissue and may promote blast cell proliferation and cancer development. We studied the effect of GH on longevity and tumour formation in Atm-deficient mice, an established model of the human cancer prone syndrome ataxia telangiectasia (AT). AT is a devastating recessive disorder that is characterized by progressive cerebellar ataxia, immunodeficiency, chromosomal instability and cancer susceptibility. Since AT patients also show endocrinological abnormalities the question has been raised as to whether GH therapy could be beneficial and/or increase the cancer risk in AT. We found that treatment with GH significantly increased longevity of Atm-deficient mice. In addition, GH ameliorated locomotoric behaviour and improved T-cell immunity. Thus, our data demonstrated that GH treatment is not necessarily accompanied by increased cancer development in diseases with chromosomal instability and cancer susceptibility and might be beneficial for AT patients.

Improved short-term survival with polyethylene glycol modified hemoglobin liposomes in critical normovolemic anemia.

OBJECTIVE: To investigate the efficacy of a polyethylene glycol (PEG) modified formulation of liposome-encapsulated hemoglobin (LEH) as an oxygen-carrying blood substitute in the treatment of critical normovolemic anemia. DESIGN AND SETTING: Prospective, controlled, randomized experimental study in a university research facility. SUBJECTS: 14 anesthetized and mechanically ventilated beagle dogs. INTERVENTIONS: Animals were splenectomized and hemodiluted by exchange of whole blood for iso-oncotic hetastarch (HES). Target parameter of the hemodilution protocol was the individual critical hemoglobin concentration (Hb(crit)) corresponding with the onset of O(2) supply dependency of total body O(2) consumption. At Hb(crit) animals were randomized to receive a bolus infusion (20[Symbol: see text]ml/kg) of either LEH (n = 7) or normal saline (NS; n = 7). Subsequently animals were observed without further intervention. MEASUREMENTS AND RESULTS: The primary endpoint was survival time after the completion of treatment; secondary endpoints were parameters of central hemodynamics, O(2) transport and tissue oxygenation. Animals in the LEH group survived significantly longer after completion of treatment (149 +/- 109 vs. 43+/- 56 min). Immediately after treatment LEH-treated animals presented with a more stable cardiovascular condition. After 30 min tissue O(2) tension on the surface of a skeletal muscle was significantly higher in the LEH group (23+/-8 vs. 9 +/- 2 mmHg). Nevertheless, treatment with LEH did not decrease mortality within the observation period. CONCLUSIONS: In this present experimental study the infusion of a PEG-modified LEH provided adequate tissue oxygenation, hemodynamic stability, and a prolongation of survival time after critical anemia. However, these effects were sustained for only a short period of time.

Influence of surfactants, polymer and doxorubicin loading on the anti-tumour effect of poly(butyl cyanoacrylate) nanoparticles in a rat glioma model.

Poly(n-butyl cyanoacrylate) nanoparticles coated with polysorbate-80 can enable the transport of bound drugs across the blood-brain barrier (BBB) after i.v. injection. In the present study the influence of different formulation parameters on the anti-tumoural effects of doxorubicin nanoparticles against glioblastoma 101/8 was investigated. The manufacturing parameters of poly(alkyl cyanoacrylate) doxorubicin-loaded nanoparticles were optimized concerning drug loading. The nanoparticles were coated with different surfactants and injected intravenously on days 2, 5 and 8 after intra-cranial implantation of glioblastoma 101/8 to rats. The survival times of all doxorubicin containing preparations, including a doxorubicin solution, increased the survival times significantly compared to untreated tumour-bearing rats. The most pronounced increase in survival was obtained with the poly(n-butyl cyanoacrylate) doxorubicin-loaded nanoparticles coated with polysorbate 80 and 35% of these animals survived for over 180 days (termination of the experiments). The other nanoparticle preparations yielded lower survival times. Poly(n-butyl cyanoacrylate) doxorubicin-loaded nanoparticles coated with polysorbate 80-coated proved to be very efficient against glioblastoma 101/8. The data suggest that the interaction of nanoparticles with the blood after injection as well as the enhanced permeability and retention effect (EPR effect) contributed differently to the anti-tumoural efficacy depending on nanoparticle formulation and surface properties.

A novel dynamic model for experimental spinal cord compression.

OBJECT: The goal of this study was to develop a novel dynamic model for experimental spinal cord compression that closely approximates neoplastic epidural compression of the spinal cord in humans. METHODS: In 30 New Zealand white rabbits, the thoracic spine was exposed via a posterior approach. On each side of one vertebral lamina a small hole was drilled caudal to the articular process. A silicone band was passed through these holes, forming a loop. The spinal dura mater was exposed via an interlaminar approach. The loop was brought into contact with the dura mater and fixed in its position encircling 270 degrees of the circumference of the spinal cord. Thereafter, the loop was gradually tightened at set times by pulling at the ends of the band and fixing them again in their new position. The spinal cord was thus increasingly compressed in a circular and dynamic manner. Neurological deficits of various degrees were created in all animals in the compression group, and the compressive effect of the loop was reliably demonstrated on MR imaging. After decompression of the spinal cord, the neurological deficits were reversible in the majority of animals, and MR imaging revealed either no signal changes or only circumscribed ones within the cord. In contrast, MR images obtained in animals that did not recover revealed the occurrence of extensive chronic myelopathy. CONCLUSIONS: This novel model features reproducibility of paresis and neurological recovery. It is a dynamic model simulating circular tumor growth and is characterized by its easy, straightforward, and cost-saving applicability.

In vivo inhibition of neutrophil activity by a FAS (CD95) stimulating module: arterial in-line application in a porcine cardiac surgery model.

OBJECTIVE: Cardiac surgery with cardiopulmonary bypass is associated with aberrant neutrophil activation and potentially severe pathogenic sequelae. This experimental study was done to evaluate a leukocyte inhibition module that rapidly inactivates neutrophils through CD95 stimulation. METHODS: German landrace pigs (4 groups, each n = 5) underwent cardiac surgery without cardiopulmonary bypass (group I), with cardiopulmonary bypass (group II), with cardiopulmonary bypass plus a leukocyte filter (group III), and with cardiopulmonary bypass plus a leukocyte inhibition module (group IV). The leukocyte filter or leukocyte inhibition module was introduced into the arterial line of the heart-lung machine. RESULTS: Leukocyte counts were decreased by up to 43% in group IV compared with values in group II (P =.023). In group IV, but not in groups I to III, no delay in spontaneous neutrophil apoptosis was observed after annexin V-propidium iodide staining. Late apoptotic (11.7%) or necrotic neutrophils (9.3%) were detected in 2 animals (group IV). Tumor necrosis factor alpha serum levels increased over time in groups I to III (>2-fold) but remained at baseline levels in group IV (P <.05). Interleukin 8-mediated chemotactic neutrophil transmigration activity increased over time in groups I to III but was totally abrogated in group IV at any time point. The perioperative increase of creatine kinase and creatine kinase MB levels was lower in groups III (1.5-fold and 1.3-fold, respectively) and IV (1.2-fold and 1.5-fold, respectively) compared with values in group II (both 1.9-fold). CONCLUSIONS: The leukocyte inhibition module downregulated cardiopulmonary bypass-related neutrophil activity and thus might be beneficial in cardiac surgery and other clinical settings with unappreciated neutrophil activation.

Standardized qualitative evaluation of scar tissue properties in an animal wound healing model.

There is a great need to establish reproducible methods for evaluative studies of wound treatment and wound healing. Validation of the healing process through optical techniques, as well as histologic and immunohistochemical methodologies, have been improved and to some extent have become well-established assays. Data relating to biomechanical properties, e.g., evaluation of the tensile strength of scar tissue that forms in experimental wound treatment strategies, are less widely available. We chose the domestic pig as an animal model in which to examine epidermal wound healing. We implanted specially made chambers that served to isolate the wounds and prevent epidermal migration from the edges. We performed histologic and immunohistochemical analyses as well as evaluation of biomechanical qualities of scar tissue using laser tensiometry. Pig skin is well suited for wound healing studies, and wound creation, implantation of the chambers, and the regular changing of dressings could all be carried out in the operating theater. In addition to established macroscopic evaluation and microscopic documentation, the need for objective biomechanical assessment of scar tissue by measuring tensile strength has been met using laser tensiometry. By optimizing methods for measuring tensile strength, it is possible to evaluate the biomechanical quality of scar tissue formed following different courses of wound treatment, as well as histologic assessment.