Blood oxygenation-level dependent cerebrovascular reactivity imaging as strategy to monitor CSF-hemoglobin toxicity.

OBJECTIVES: Cell-free hemoglobin in the cerebrospinal fluid (CSF-Hb) may be one of the main drivers of secondary brain injury after aneurysmal subarachnoid hemorrhage (aSAH). Haptoglobin scavenging of CSF-Hb has been shown to mitigate cerebrovascular disruption. Using digital subtraction angiography (DSA) and blood oxygenation-level dependent cerebrovascular reactivity imaging (BOLD-CVR) the aim was to assess the acute toxic effect of CSF-Hb on cerebral blood flow and autoregulation, as well as to test the protective effects of haptoglobin. METHODS: DSA imaging was performed in eight anesthetized and ventilated sheep (mean weight: 80.4 kg) at baseline, 15, 30, 45 and 60 minutes after infusion of hemoglobin (Hb) or co-infusion with haptoglobin (Hb:Haptoglobin) into the left lateral ventricle. Additionally, 10 ventilated sheep (mean weight: 79.8 kg) underwent BOLD-CVR imaging to assess the cerebrovascular reserve capacity. RESULTS: DSA imaging did not show a difference in mean transit time or cerebral blood flow. Whole-brain BOLD-CVR compared to baseline decreased more in the Hb group after 15 minutes (Hb vs Hb:Haptoglobin: -0.03 ± 0.01 vs -0.01 ± 0.02) and remained diminished compared to Hb:Haptoglobin group after 30 minutes (Hb vs Hb:Haptoglobin: -0.03 ± 0.01 vs 0.0 ± 0.01), 45 minutes (Hb vs Hb:Haptoglobin: -0.03 ± 0.01 vs 0.01 ± 0.02) and 60 minutes (Hb vs Hb:Haptoglobin: -0.03 ± 0.02 vs 0.01 ± 0.01). CONCLUSION: It is demonstrated that CSF-Hb toxicity leads to rapid cerebrovascular reactivity impairment, which is blunted by haptoglobin co-infusion. BOLD-CVR may therefore be further evaluated as a monitoring strategy for CSF-Hb toxicity after aSAH.

Effects of buprenorphine, butorphanol or tramadol premedication on anaesthetic induction with alfaxalone in common marmosets (Callithrix jacchus).

OBJECTIVE: To investigate the clinical and physiological effects of intravenous (IV) alfaxalone alone or in combination with buprenorphine, butorphanol or tramadol premedication in marmosets. STUDY DESIGN: Prospective, randomized, blinded, crossover design. ANIMALS: Nine healthy marmosets (391 ± 48 g, 3.7 ± 2.2 years old). METHODS: Meloxicam 0.20 mg kg-1 subcutaneously, atropine 0.05 mg kg-1 intramuscularly (IM) and either buprenorphine 20 µg kg-1 IM (BUP-A), butorphanol 0.2 mg kg-1 IM (BUT-A), tramadol 1.5 mg kg-1 IM (TRA-A) or no additional drug (control) were administered to all marmosets as premedication. After 1 hour, anaesthesia was induced with 16 mg kg-1 alfaxalone IV. All animals received all protocols. The order of protocol allocation was randomized with a minimum 28 day wash-out period. During anaesthesia, respiratory and pulse rates, rectal temperature, haemoglobin oxygen saturation, arterial blood pressure, palpebral and pedal withdrawal reflexes and degree of muscle relaxation were assessed and recorded every 5 minutes. Quality of induction and recovery were assessed. Duration of induction, immobilization and recovery were recorded. Blood samples were analysed for aspartate aminotransferase, creatine kinase and lactate dehydrogenase concentrations. The protocols were compared using paired t tests, Wilcoxon's signed-rank test with Bonferroni's corrections and linear mixed effect models where appropriate. RESULTS: Out of nine animals, apnoea was noted in eight animals administered protocol BUP-A and two animals administered protocol BUT-A. With TRA-A and control protocols, apnoea was not observed. No other significant differences in any of the parameters were found; however, low arterial blood pressures and hypoxia occurred in TRA-A. CONCLUSIONS AND CLINICAL RELEVANCE: Our study employing different premedications suggests that the previously published dose of 16 mg kg-1 alfaxalone is too high when used with premedication because we found a high incidence of complications including apnoea (BUP-A), hypotension and hypoxaemia (TRA-A). Appropriate monitoring and countermeasures are recommended.

A novel, non-adhesive, precipitating liquid embolic implant with intrinsic radiopacity: feasibility and safety animal study.

OBJECTIVES: To evaluate a novel, ready-to-use, iodinated polyvinyl alcohol polymer embolic implant. METHODS: Under good laboratory practice conditions, 26 pigs were investigated. A complex arteriovenous malformation (AVM) model was created in 16 animals, and a simple rete model was used in the remaining 10 animals. The novel material was used for embolization in 22 animals, and a commercially available liquid embolic material in 4 animals as a control group. Animals were killed at 2 days, 3 months and 6 months. Feasibility, efficacy and safety were evaluated radiologically, clinically and histologically. RESULTS: Preparation was easy, without risk of catheter clogging or adhesiveness. Embolic delivery was well controlled under subtracted fluoroscopy. Visibility was homogeneous throughout the injection and the material behaved cohesively upon delivery. Best lesion penetration was obtained with the use of proximal microballoon occlusion. Unforeseen over-dilution of the test material by DMSO prefilled in the microballoon hub changed the material properties and caused inadvertent cerebral embolization leading to death in five animals. This phenomenon was avoided by practical measures. The casts produced no beam-hardening artefacts on CT scans. Histology showed excellent biocompatibility. CONCLUSIONS: Embolization with this novel, iodinated, precipitating polymer was feasible and effective. Care should be taken during delivery to avoid over-dilution of the material by prefilled DMSO. The material is promising for embolization of AVMs and hypervascular lesions. KEY POINTS: • The intrinsically opaque precipitating polymer has adequate fluoroscopic visibility • The polymer does not induce shading or beam-hardening artefacts on CT • The novel liquid embolic material does not require lengthy preparation • Lack of implant adherence reduces the risk of entrapment of the delivery catheter.

Clinical evaluation of intranasal medetomidine-ketamine and medetomidine-S(+)-ketamine for induction of anaesthesia in rabbits in two centres with two different administration techniques.

OBJECTIVE: The aim was to compare efficacy and side effects of induction with medetomidine-ketamine or medetomidine-S(+)-ketamine by intranasal (IN) instillation in rabbits and to evaluate both protocols during subsequent isoflurane anaesthesia. STUDY DESIGN: Prospective, blinded, randomized experimental study in two centres. ANIMALS: Eighty-three healthy New Zealand White rabbits undergoing tibial or ulnar osteotomy. METHODS: Medetomidine (0.2 mg kg-1) with 10 mg kg-1 ketamine (MK) or 5 mg kg-1 S(+)-ketamine (MS) was administered IN to each rabbit in a randomized fashion. In Centre 1 (n = 42) rabbits were held in sternal recumbency, and in Centre 2 (n = 41) in dorsal recumbency, during drug instillation. Adverse reactions were recorded. If a rabbit swallowed during endotracheal intubation, half of the initial IN dose was repeated and intubation was re-attempted after 5 minutes. Anaesthesia was maintained with isoflurane. Heart rate, blood pressure, endtidal carbon dioxide concentration and blood gases were recorded. Data were analysed using Student's t-test, Mann-Whitney test and Fisher's exact test. RESULTS: In all, 39 animals were assigned to the MK group and 44 to the MS group. Two rabbits in the MS group held in dorsal recumbency died after instillation of the drug. Eight (MK) and 11 rabbits (MS) were insufficiently anaesthetized and received a second IN dose. One rabbit in MK and three in MS required an isoflurane mask induction after the second IN dose. There were no significant differences between treatments for induction, intraoperative data, blood gas values and recovery data. CONCLUSION AND CLINICAL RELEVANCE: This study indicated that medetomidine-ketamine and medetomidine-S(+)-ketamine were effective shortly after IN delivery, but in dorsal recumbency IN administration of S(+)-ketamine led to two fatalities. Nasal haemorrhage was noted in both cases; however, the factors leading to death have not been fully elucidated.

Plasma concentrations of transdermal fentanyl and buprenorphine in pigs (Sus scrofa domesticus).

OBJECTIVE: To determine the absorption characteristics of fentanyl and buprenorphine administered transdermally in swine. STUDY DESIGN: A randomized comparative experimental trial. ANIMALS: Twenty-four Yorkshire gilts weighing 27.8±2.2 kg (mean±standard deviation). METHODS: Animals were randomly assigned to different doses of transdermal patches (TPs) of fentanyl (50 µg hour-1, 75 µg hour-1 and 100 µg hour-1) or buprenorphine (35 µg hour-1 and 70 µg hour-1), once or twice. Thirteen blood samples were obtained for each TP applied. Plasma concentrations were determined, and the area under the curve, peak serum concentration (Cmax) and time to Cmax were calculated. RESULTS: Fentanyl: Cmax was observed at different time points: for the first TP application: 30 hours for 50 µg hour-1, 6 hours for 75 µg hour-1 and 100 µg hour-1 patches; and for the second TP application: 30 hours for 50 µg hour-1 and 36 hours for 75 µg hour-1 patches. Buprenorphine: serum concentrations were not detected for the 35 µg hour-1 patch; Cmax was observed at different times for the 70 µg hour-1 patch: 18 hours (n = 1), 24 hours (n = 3), 30 hours (n = 1) and 42 hours (n = 1) after application of the first patch and 12 hours after the second patch. CONCLUSIONS AND CLINICAL RELEVANCE: A relevant serum concentration obtained with fentanyl TP dosed at 75 µg hour-1 or 100 µg hour-1suggests that TPs could represent an analgesia option for laboratory pigs weighing 25-30 kg. As concentrations of buprenorphine were variable, this study does not support the use of buprenorphine TPs in pigs. Consecutive fentanyl or buprenorphine TPs did not provide reliable serum concentrations. Further pharmacokinetic studies and analgesiometric tests in swine are needed to confirm the clinical adequacy of TPs.

A new-generation, low-permeability flow diverting device for treatment of saccular aneurysms.

OBJECTIVES: We report a preclinical comparative study of a 96-strand braided flow diverter. METHODS: The 96-strand braided device was compared with the currently commercially available flow diverter with 48 strands. The devices were implanted across the neck of 12 elastase-induced aneurysms in New Zealand White rabbits and followed for 1 and 3 months (n = 6 respectively). Aneurysm occlusion rates, parent artery stenosis and patency of jailed branch occlusions were assessed by angiography, histology and scanning electron microscopy studies. RESULTS: It was feasible to navigate and implant the 96-strand device over the aneurysm orifice in all cases. At follow-up two aneurysms in the 48-strand vs. one in the 96-strand group were not occluded. This aneurysm from the 96-strand group however had a tracheal branch arising from the sac and showed a reverse remodelling of the vascular pouch at 3 months. In the occluded aneurysms, the parent artery was always completely reconstructed and the aneurysm orifice was sealed with neointimal tissue. No in-stent stenosis or jailed branch artery occlusion was observed. CONCLUSIONS: The 96-strand flow diverter proved to be safe, biocompatible and haemodynamically effective, induced stable occlusion of aneurysms and led to reverse remodelling of the parent artery. KEY POINTS: • Flow diversion has been introduced to improve endovascular treatment of cerebral aneurysms • A new low-permeability flow diverter is feasible for parent artery reconstruction. • The Silk 96 flow diverter appears effective at inducing aneurysm healing. • The covered branches remained patent at follow-up.

Preliminary study on carprofen concentration measurements after transcutaneous treatment with Vetdrop® in a microfracture joint defect model in sheep.

BACKGROUND: The present preliminary study describes concentration time courses of the NSAID carprofen in the plasma and synovial fluid in a microfrature sheep model after transcutaneous treatments with a novel application device (Vetdrop®). To treat circumscribed inflammatory processes a transcutaneous application device could potentially be beneficial. After transcutaneous application normally lower systemic concentrations are measured which may reduce the incidence of side effects, whereas efficacy is still maintained. In this study carprofen was used based on its capacity to provide analgesia after orthopaedic procedures in sheep and it is considered that it may have a positive influence on the healing of cartilage in low concentrations. RESULTS: In all transcutaneously treated animals, carprofen plasma concentrations exceeded those of synovial fluid, although plasma levels remained significantly reduced (300-fold) as compared to carprofen administered intravenously. Furthermore, in contrast to the intravenously treated animals, a modest accumulation of carprofen in plasma and synovial fluid was observed in the transcutaneously treated animals over the 6-week treatment period. CONCLUSIONS: The transcutaneously administered carprofen using the Vetdrop® device penetrated the skin and both, plasma- and synovial concentrations could be measured repeatedly over time. This novel device may be considered a valuable transcutaneous drug delivery system.

Studying Edema Formation After Release of the Infraspinatus Muscle as an Experimental Model of Rotator Cuff Lesions in Sheep: A Histological Analysis.

BACKGROUND: Muscle edema formation and inflammatory processes are early manifestations of acute rotator cuff lesions in sheep. Histological analysis of affected muscles revealed edema formation, inflammatory changes, and muscle tissue disruption in MRs. HYPOTHESIS: Edema contributes to inflammatory reactions and early muscle fiber degeneration before the onset of fatty infiltration. STUDY DESIGN: Controlled laboratory study. METHODS: Osteotomy of the greater tuberosity, including the insertion of the infraspinatus tendon, was performed on 14 sheep. These experimental animal models were divided into 2 groups: a nontrauma group with surgical muscle release alone (7 sheep) and a trauma group with standardized application of additional trauma to the musculotendinous unit (7 sheep). Excisional biopsy specimens of the infraspinatus muscle were taken at 0, 3, and 4 weeks. RESULTS: Edema formation was histologically demonstrated in both groups and peaked at 3 weeks. At 3 weeks, signs of muscle fiber degeneration were observed. At 4 weeks, ingrowth of loose alveolar and fibrotic tissue between fibers was detected. Fatty tissue was absent. The diameter of muscle fibers increased in both groups, albeit to a lesser degree in the trauma group, and practically normalized at 4 weeks. Immunohistology revealed an increase in macrophage types 1 and 2, as well as inflammatory mediators such as prostaglandin E2 and nuclear factor kappa-light-chain-enhancer of activated B cells. CONCLUSION: Early muscle edema and concomitant inflammation precede muscle fiber degeneration and fibrosis. Edema formation results from tendon release alone and is only slightly intensified by additional trauma. CLINICAL RELEVANCE: This study illustrates that early edema formation and inflammation elicit muscle fiber degeneration that precedes fatty infiltration. Should this phenomenon be applicable to human traumatic rotator cuff tears, then surgery should be performed as soon as possible, ideally within the first 21 days after injury.

Haptoglobin Attenuates Cerebrospinal Fluid Hemoglobin-Induced Neurological Deterioration in Sheep.

Secondary brain injury (SBI) occurs with a lag of several days post-bleeding in patients with aneurysmal subarachnoid hemorrhage (aSAH) and is a strong contributor to mortality and long-term morbidity. aSAH-SBI coincides with cell-free hemoglobin (Hb) release into the cerebrospinal fluid. This temporal association and convincing pathophysiological concepts suggest that CSF-Hb could be a targetable trigger of SBI. However, sparse experimental evidence for Hb's neurotoxicity in vivo defines a significant research gap for clinical translation. We modeled the CSF-Hb exposure observed in aSAH patients in conscious sheep, which allowed us to assess neurological functions in a gyrencephalic species. Twelve animals were randomly assigned for 3-day bi-daily intracerebroventricular (ICV) injections of either Hb or Hb combined with the high-affinity Hb scavenger protein haptoglobin (Hb-Hp, CSL888). Repeated CSF sampling confirmed clinically relevant CSF-Hb concentrations. This prolonged CSF-Hb exposure over 3 days resulted in disturbed movement activity, reduced food intake, and impaired observational neuroscores. The Hb-induced neurotoxic effects were significantly attenuated when Hb was administered with equimolar haptoglobin. Preterminal magnetic resonance imaging (MRI) showed no CSF-Hb-specific structural brain alterations. In both groups, histology demonstrated an inflammatory response and revealed enhanced perivascular histiocytic infiltrates in the Hb-Hp group, indicative of adaptive mechanisms. Heme exposure in CSF and iron deposition in the brain were comparable, suggesting comparable clearance efficiency of Hb and Hb-haptoglobin complexes from the intracranial compartment. We identified a neurological phenotype of CSF-Hb toxicity in conscious sheep, which is rather due to neurovascular dysfunction than structural brain injury. Haptoglobin was effective at attenuating CSF-Hb-induced neurological deterioration, supporting its therapeutic potential.

Effects of shape and structure of a new 3D-printed personalized bioresorbable tracheal stent on fit and biocompatibility in a rabbit model.

To date, several types of airway stents are available to treat central airway obstructions. However, the ideal stent that can overcome anatomical, mechanical and microbiological issues is still awaited. In addition, therapeutic effect and self-elimination of these stents are desirable properties, which pose an additional challenge for development and manufacturing. We aimed to create a prototype bioresorbable tracheal stent with acceptable clinical tolerance, fit and biocompatibility, that could be tested in a rabbit model and in the future be further optimized to enable drug-elution and ensure local therapeutic effect. Twenty-one New Zealand White Rabbits received five different types of bioresorbable tracheal stents, 3D-printed from poly(D,L-lactide-co-ε-caprolactone) metacrylates. Various configurations were tested for their functionality and improved until the best performing prototype could undergo detailed in vivo assessment, regarding clinical tolerance, migration and biocompatibility. Previously tested types of 3D printed stents in our preliminary study required improvement due to several problems, mainly related to breakage, unreliable stability and/or migration within the trachea. Abandoned or refined pre-prototypes were not analyzed in a comparative way. The final best performing prototype stent (GSP2 (Group Stent Prototype 2), n = 8) allowed a transoral application mode and showed good clinical tolerance, minimal migration and acceptable biocompatibility. The good performance of stent type GSP2 was attributed to the helix-shaped surface structure, which was therefore regarded as a key-feature. This prototype stent offers the possibility for further research in a large animal model to confirm the promising data and assess other properties such as bioresorption.

Transplantation and tracking of human-induced pluripotent stem cells in a pig model of myocardial infarction: assessment of cell survival, engraftment, and distribution by hybrid single photon emission computed tomography/computed tomography of sodium iodide symporter transgene expression.

BACKGROUND: Evaluation of novel cellular therapies in large-animal models and patients is currently hampered by the lack of imaging approaches that allow for long-term monitoring of viable transplanted cells. In this study, sodium iodide symporter (NIS) transgene imaging was evaluated as an approach to follow in vivo survival, engraftment, and distribution of human-induced pluripotent stem cell (hiPSC) derivatives in a pig model of myocardial infarction. METHODS AND RESULTS: Transgenic hiPSC lines stably expressing a fluorescent reporter and NIS (NIS(pos)-hiPSCs) were established. Iodide uptake, efflux, and viability of NIS(pos)-hiPSCs were assessed in vitro. Ten (±2) days after induction of myocardial infarction by transient occlusion of the left anterior descending artery, catheter-based intramyocardial injection of NIS(pos)-hiPSCs guided by 3-dimensional NOGA mapping was performed. Dual-isotope single photon emission computed tomographic/computed tomographic imaging was applied with the use of (123)I to follow donor cell survival and distribution and with the use of (99m)TC-tetrofosmin for perfusion imaging. In vitro, iodide uptake in NIS(pos)-hiPSCs was increased 100-fold above that of nontransgenic controls. In vivo, viable NIS(pos)-hiPSCs could be visualized for up to 15 weeks. Immunohistochemistry demonstrated that hiPSC-derived endothelial cells contributed to vascularization. Up to 12 to 15 weeks after transplantation, no teratomas were detected. CONCLUSIONS: This study describes for the first time the feasibility of repeated long-term in vivo imaging of viability and tissue distribution of cellular grafts in large animals. Moreover, this is the first report demonstrating vascular differentiation and long-term engraftment of hiPSCs in a large-animal model of myocardial infarction. NIS(pos)-hiPSCs represent a valuable tool to monitor and improve current cellular treatment strategies in clinically relevant animal models.

Bone augmentation for cancellous bone- development of a new animal model.

BACKGROUND: Reproducible and suitable animal models are required for in vivo experiments to investigate new biodegradable and osteoinductive biomaterials for augmentation of bones at risk for osteoporotic fractures. Sheep have especially been used as a model for the human spine due to their size and similar bone metabolism. However, although sheep and human vertebral bodies have similar biomechanical characteristics, the shape of the vertebral bodies, the size of the transverse processes, and the different orientation of the facet joints of sheep are quite different from those of humans making the surgical approach complicated and unpredictable. Therefore, an adequate and safe animal model for bone augmentation was developed using a standardized femoral and tibia augmentation site in sheep. METHODS: The cancellous bone of the distal femur and proximal tibia were chosen as injection sites with the surgical approach via the medial aspects of the femoral condyle and proximal tibia metaphysis (n = 4 injection sites). For reproducible drilling and injection in a given direction and length, a custom-made c-shaped aiming device was designed. Exact positioning of the aiming device and needle positioning within the intertrabecular space of the intact bone could be validated in a predictable and standardized fashion using fluoroscopy. After sacrifice, bone cylinders (Ø 32 mm) were harvested throughout the tibia and femur by means of a diamond-coated core drill, which was especially developed to harvest the injected bone area exactly. Thereafter, the extracted bone cylinders were processed as non-decalcified specimens for µCT analysis, histomorphometry, histology, and fluorescence evaluation. RESULTS: The aiming device could be easily placed in 63 sheep and assured a reproducible, standardized injection area. In four sheep, cardiovascular complications occurred during surgery and pulmonary embolism was detected by computed tomography post surgery in all of these animals. The harvesting and evaluative methods assured a standardized analysis of all samples. CONCLUSIONS: This experimental animal model provides an excellent basis for testing new biomaterials for their suitability as bone augmentation materials. Concomitantly, similar cardiovascular changes occur during vertebroplasties as in humans, thus making it a suitable animal model for studies related to vertebroplasty.

Combined electric and magnetic field therapy for bone repair and regeneration: an investigation in a 3-mm and an augmented 17-mm tibia osteotomy model in sheep.

BACKGROUND: Therapies using electromagnetic field technology show evidence of enhanced bone regeneration at the fracture site, potentially preventing delayed or nonunions. METHODS: Combined electric and magnetic field (CEMF) treatment was evaluated in two standardized sheep tibia osteotomy models: a 3-mm non-critical size gap model and a 17-mm critical size defect model augmented with autologous bone grafts, both stabilized with locking compression plates. CEMF treatment was delivered across the fracture gap twice daily for 90 min, starting 4 days postoperatively (post-OP) until sacrifice (9 or 12 weeks post-OP, respectively). Control groups received no CEMF treatment. Bone healing was evaluated radiographically, morphometrically (micro-CT), biomechanically and histologically. RESULTS: In the 3-mm gap model, the CEMF group (n = 6) exhibited higher callus mineral density compared to the Control group (n = 6), two-fold higher biomechanical torsional rigidity and a histologically more advanced callus maturity (no statistically significant differences). In the 17-mm graft model, differences between the Control (n = 6) and CEMF group (n = 6) were more pronounced. The CEMF group showed a radiologically more advanced callus, a higher callus volume (p = 0.003) and a 2.6 × higher biomechanical torsional rigidity (p = 0.024), combined with a histologically more advanced callus maturity and healing. CONCLUSIONS: This study showed that CEMF therapy notably enhanced bone healing resulting in better new bone structure, callus morphology and superior biomechanical properties. This technology could transform a standard inert orthopedic implant into an active device stimulating bone tissue for accelerated healing and regeneration.

Oral Use of Therapeutic Carbon Monoxide for Anyone, Anywhere, and Anytime.

Carbon monoxide (CO) is a therapeutic gas with therapeutic potential in intestinal bowel disease. Therapeutic efficacy in the gastrointestinal tract (GIT) must be paired with safe and convenient use. Therefore, we designed an oral CO releasing system (OCORS) pairing tunable CO release into the GIT while preventing the release of any other molecule from within the device, causing safety concerns. The dimensions of the device, which is manufactured from 3D printed components, are within compendial limits. This is achieved by controlling CO decarbonylation from a molybdenum complex with a FeCl3 solution. OCORS' surrounding silicon membranes control release rates, as does the loading with carbonylated molybdenum complex and FeCl3 solution. Herein we describe the development of the system, the characterization of the CO releasing molecule (CORM), and the CO release kinetics of the overall system. Neither the CORM nor isocyanoacetate as a potential reaction byproduct were cytotoxic. Finally, we demonstrated by design validation in an in vivo porcine model that, except for the release of the therapeutic CO, OCORS isolates all components during transit through the stomach. We could show that OCORS generated and released CO locally into the stomach of the animals without systemic exposure, measured as the carboxyhemoglobin content in the blood of the pigs. In conclusion, OCORS derisks oral development by limiting patient exposure to (desirable) CO while preventing contact with any further (undesirable) chemical, by-, or degradation products. CO generating devices come in reach, which now can be used by anyone, anywhere, and anytime.

Osseointegration and biocompatibility of different metal implants--a comparative experimental investigation in sheep.

BACKGROUND: In the present study, 4 different metallic implant materials, either partly coated or polished, were tested for their osseointegration and biocompatibility in a pelvic implantation model in sheep. METHODS: Materials to be evaluated were: Cobalt-Chrome (CC), Cobalt-Chrome/Titanium coating (CCTC), Cobalt-Chrome/Zirconium/Titanium coating (CCZTC), Pure Titanium Standard (PTST), Steel, TAN Standard (TANST) and TAN new finish (TANNEW). Surgery was performed on 7 sheep, with 18 implants per sheep, for a total of 63 implants. After 8 weeks, the specimens were harvested and evaluated macroscopically, radiologically, biomechanically (removal torque), histomorphometrically and histologically. RESULTS: Cobalt-Chrome screws showed significantly (p = 0.031) lower removal torque values than pure titanium screws and also a tendency towards lower values compared to the other materials, except for steel. Steel screws showed no significant differences, in comparison to cobalt-chrome and TANST, however also a trend towards lower torque values than the remaining materials. The results of the fluorescence sections agreed with those of the biomechanical test. Histomorphometrically, there were no significant differences of bone area between the groups. The BIC (bone-to-implant-contact), used for the assessment of the osseointegration, was significantly lower for cobalt-chrome, compared to steel (p = 0.001). Steel again showed a lower ratio (p = 0.0001) compared to the other materials. CONCLUSION: This study demonstrated that cobalt-chrome and steel show less osseointegration than the other metals and metal-alloys. However, osseointegration of cobalt-chrome was improved by zirconium and/or titanium based coatings (CCTC, TANST, TAN, TANNEW) being similar as pure titanium in their osseointegrative behavior.

Biodegradable sleeves for metal implants to prevent implant-associated infection: an experimental in vivo study in sheep.

OBJECTIVE: To evaluate biocompatibility of biodegradable sleeves containing antimicrobial agents, designed for local drug delivery to prevent implant-related infection. STUDY DESIGN: Synthetic polyester sleeves (a copolymer of glycolide, caprolactone, trimethylene carbonate, lactide) were cast as thin films. The antimicrobial agents incorporated in the sleeves included gentamicin sulfate, triclosan, or a combination of these drugs. ANIMALS: Adult sheep (n = 15). METHODS: Two limited contact dynamic compression plates (LC-DCP) with or without sleeves were implanted on tibiae (bilateral) of 15 sheep. Sleeves were placed over the plates before implantation. Beneath half of the plates, 5-mm drill hole defects were made in the near cortex. Samples were harvested 4 weeks later for histology and microradiography. RESULTS: Macroscopically, no irritation of bone or adjacent tissue was seen. Small remnants of sleeves were visible on histology, and positively correlated with the presence of macrophages and foreign body cells. Thick sections showed no difference between the test samples and controls in terms of fibrous capsule formation, periosteal remodeling, and defect remodeling. Inflammatory cells, macrophages, and foreign body cells were more prominent in sections with sleeves, but were not statistically significantly different from controls. Cell numbers were within normal physiologic limits normally seen as cellular response to foreign bodies consisting of polymers. CONCLUSION: The normal healing response indicated that the biodegradable sleeves demonstrate tissue biocompatibility.

Studying Edema Formation After Release of the Infraspinatus Tendon as an Experimental Model of Rotator Cuff Tears in Sheep: A Preliminary Imaging and Morphological Analysis.

BACKGROUND: The cause, extent, and role of muscle edema for muscle degeneration are unknown and not considered in the current literature. In vivo experiments were designed to prove muscle edema formation in the early period in a sheep model of acute rotator cuff tears. HYPOTHESIS: Muscle edema occurs after tendon release with or without additional stretching trauma and may be associated with muscle retraction and subsequent muscle degeneration. STUDY DESIGN: Controlled laboratory study. METHODS: A sheep model with acute release of the infraspinatus tendon was used. An osteotomy of the greater tuberosity, including the insertion of the infraspinatus tendon, was performed in 14 sheep. To demonstrate presence of edema, magnetic resonance imaging scans were performed at 0, 2, and 4 weeks using T1-weighted, T2-weighted, proton density-weighted, and Dixon sequences. Excisional biopsy specimens were taken at 0, 3, and 4 weeks (histological results will be reported in a later publication). Two injury models were created: a nontrauma group that consisted of muscle release alone and a trauma group that included additional standardized traction to the musculotendinous unit. Evaluation of T1- and T2-weighted images included calculation of pennation angle, muscle fiber length, signal intensity (edema), and muscle volume. Muscle wet weight and volume were measured at sacrifice. RESULTS: Edema formation was shown in all sheep and slightly more pronounced in the trauma group, where muscle intensity increased significantly between time point 0 (200 Grey Value (GV)) and weeks 2, 3, and 4 (300 GV). Edema formation started early after tendon release with a plateau between 3 and 4 weeks. Deterioration of muscle fiber bundles began also after tendon release with a peak at 4 weeks. Muscle volume decreased steadily over time. CONCLUSION: Muscle edema appeared early after rotator cuff tendon release, was more pronounced in the trauma group, and reached a plateau after 3 to 4 weeks. Muscle fatty content decreased within the short period of 4 weeks owing to a dilution effect. Muscle edema seems to be an essential factor in cuff tears and subsequent muscle retraction and degeneration. CLINICAL RELEVANCE: This study demonstrates a new type of muscle edema of retraction and describes the characteristics of edema associated with a retracted rotator cuff tear.

Multilingual validation of the short form of the Unesp-Botucatu Feline Pain Scale (UFEPS-SF).

Background: Pain is the leading cause of animal suffering, hence the importance of validated tools to ensure its appropriate evaluation and treatment. We aimed to test the psychometric properties of the short form of the Unesp-Botucatu Feline Pain Scale (UFEPS-SF) in eight languages. Methods: The original scale was condensed from ten to four items. The content validation was performed by five specialists in veterinary anesthesia and analgesia. The English version of the scale was translated and back-translated into Chinese, French, German, Italian, Japanese, Portuguese and Spanish by fluent English and native speaker translators. Videos of the perioperative period of 30 cats submitted to ovariohysterectomy (preoperative, after surgery, after rescue analgesia and 24 h after surgery) were randomly evaluated twice (one-month interval) by one evaluator for each language unaware of the pain condition. After watching each video, the evaluators scored the unidimensional, UFEPS-SF and Glasgow composite multidimensional feline pain scales. Statistical analyses were carried out using R software for intra and interobserver reliability, principal component analysis, criteria concurrent and predictive validities, construct validity, item-total correlation, internal consistency, specificity, sensitivity, the definition of the intervention score for rescue analgesia and diagnostic uncertainty zone, according to the receiver operating characteristic (ROC) curve. Results: UFEPS-SF intra- and inter-observer reliability were ≥0.92 and 0.84, respectively, for all observers. According to the principal component analysis, UFEPS-SF is a unidimensional scale. Concurrent criterion validity was confirmed by the high correlation between UFEPS-SF and all other scales (≥0.9). The total score and all items of UFEPS-SF increased after surgery (pain), decreased to baseline after analgesia and were intermediate at 24 h after surgery (moderate pain), confirming responsiveness and construct validity. Item total correlation of each item (0.68-0.83) confirmed that the items contributed homogeneously to the total score. Internal consistency was excellent (≥0.9) for all items. Both specificity (baseline) and sensitivity (after surgery) based on the Youden index was 99% (97-100%). The suggestive cut-off score for the administration of analgesia according to the ROC curve was ≥4 out of 12. The diagnostic uncertainty zone ranged from 3 to 4. The area under the curve of 0.99 indicated excellent discriminatory capacity of UFEPS-SF. Conclusions: The UFEPS-SF and its items, assessed by experienced evaluators, demonstrated very good repeatability and reproducibility, content, criterion and construct validities, item-total correlation, internal consistency, excellent sensitivity and specificity and a cut-off point indicating the need for rescue analgesia in Chinese, French, English, German, Italian, Japanese, Portuguese and Spanish.

Coronary optical frequency domain imaging (OFDI) for in vivo evaluation of stent healing: comparison with light and electron microscopy.

AIMS: Coronary late stent thrombosis, a rare but devastating complication, remains an important concern in particular with the increasing use of drug-eluting stents. Notably, pathological studies have indicated that the proportion of uncovered coronary stent struts represents the best morphometric predictor of late stent thrombosis. Intracoronary optical frequency domain imaging (OFDI), a novel second-generation optical coherence tomography (OCT)-derived imaging method, may allow rapid imaging for the detection of coronary stent strut coverage with a markedly higher precision when compared with intravascular ultrasound, due to a microscopic resolution (axial approximately 10-20 microm), and at a substantially increased speed of image acquisition when compared with first-generation time-domain OCT. However, a histological validation of coronary OFDI for the evaluation of stent strut coverage in vivo is urgently needed. Hence, the present study was designed to evaluate the capacity of coronary OFDI by electron (SEM) and light microscopy (LM) analysis to detect and evaluate stent strut coverage in a porcine model. METHODS AND RESULTS: Twenty stents were implanted into 10 pigs and coronary OFDI was performed after 1, 3, 10, 14, and 28 days. Neointimal thickness as detected by OFDI correlated closely with neointimal thickness as measured by LM (r = 0.90, P < 0.01). The comparison of stent strut coverage as detected by OFDI and SEM analysis revealed an excellent agreement (r = 0.96, P < 0.01). In particular, stents completely covered by OFDI analysis were also completely covered by SEM analysis. All incompletely covered stents by OFDI were also incompletely covered by SEM. Analyses of fibrin-covered stent struts suggested that these may rarely be detected as uncovered stent struts by OFDI. Importantly, optical density measurements revealed a significant difference between fibrin- and neointima-covered coronary stent struts [0.395 (0.35-0.43) vs. 0.53 (0.47-0.57); P < 0.001], suggesting that differences in optical density provide information on the type of stent strut coverage. The sensitivity and specificity for detection of fibrin vs. neointimal coverage was evaluated using receiver-operating characteristic analysis. CONCLUSION: The present study demonstrates that OFDI is a highly promising tool for accurate evaluation of coronary stent strut coverage, as supported by a high agreement between OFDI and light and electron microscopic analysis. Furthermore, our data indicate that optical density measurements can provide additional information with respect to the type of stent strut coverage, i.e. fibrin vs. neointimal coverage. Therefore, coronary OFDI analysis will provide important information on the biocompatibility of coronary stents.

Industrial Development of Standardized Fetal Progenitor Cell Therapy for Tendon Regenerative Medicine: Preliminary Safety in Xenogeneic Transplantation.

Tendon defects require multimodal therapeutic management over extensive periods and incur high collateral burden with frequent functional losses. Specific cell therapies have recently been developed in parallel to surgical techniques for managing acute and degenerative tendon tissue affections, to optimally stimulate resurgence of structure and function. Cultured primary human fetal progenitor tenocytes (hFPT) have been preliminarily considered for allogeneic homologous cell therapies, and have been characterized as stable, consistent, and sustainable cell sources in vitro. Herein, optimized therapeutic cell sourcing from a single organ donation, industrial transposition of multi-tiered progenitor cell banking, and preliminary preclinical safety of an established hFPT cell source (i.e., FE002-Ten cell type) were investigated. Results underlined high robustness of FE002-Ten hFPTs and suitability for sustainable manufacturing upscaling within optimized biobanking workflows. Absence of toxicity or tumorigenicity of hFPTs was demonstrated in ovo and in vitro, respectively. Furthermore, a 6-week pilot good laboratory practice (GLP) safety study using a rabbit patellar tendon partial-thickness defect model preliminarily confirmed preclinical safety of hFPT-based standardized transplants, wherein no immune reactions, product rejection, or tumour formation were observed. Such results strengthen the rationale of the multimodal Swiss fetal progenitor cell transplantation program and prompt further investigation around such cell sources in preclinical and clinical settings for musculoskeletal regenerative medicine.