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Background Buprenorphine is one of the most used analgesics for postoperative pain in rabbits. The recommended dose in rabbits (0.01–0.05 mg/kg) is the same for intravenous (IV), intramuscular (IM), and subcutaneous (SC) administration, despite lack of pharmacokinetic data. Five male and five female New Zealand White rabbits (mean ± SD body weight 3.1 ± 0.3 kg) were administered 0.05 mg/kg buprenorphine by the IV, IM and SC routes and 0.1 mg/kg by the SC route, in a cross-over design with two-week wash-out periods between treatments. Blood was collected before, and up to 8 h post buprenorphine injection, for determination of serum levels by UPHLC-MS/MS. Results The area under the time concentration curve (AUC0-t) was lower after SC (398 ± 155 ng/mL/min) than IM (696 ± 168 ng/mL/min, p p p = 0.006). The elimination half-life was longer after SC (260 ± 120 min) than after IM (148 ± 26 min, p = 0.002) as well as IV (139 ± 33 min) injection (p p = 0.022) and 165% in male rabbits (p p = 0.6), whereas it increased in the males (71 ± 23%, p = 0.008). Conclusions The lower bioavailability of 0.05 mg/kg buprenorphine after SC administration could explain the lack of efficacy seen in clinical pain studies in rabbits, using this route. For immediate pain relief, IV or IM administration is therefore be recommended, whereas SC administration may be useful to sustain analgesic serum levels, once efficient pain relief has been achieved. The current data do not support an increase in dose to compensate for the lower SC bioavailability.

Introduction Glucagon-like peptide-1 (GLP-1) increases insulin secretion from pancreatic beta-cells and GLP-1 receptor (GLP-1R) agonists are widely used as treatment for type 2 diabetes mellitus. Studying occupancy of the GLP-1R in various tissues is challenging due to lack of quantitative, repeatable assessments of GLP-1R density. The present study aimed to describe the quantitative distribution of GLP-1Rs and occupancy by endogenous GLP-1 during oral glucose tolerance test (OGTT) in pigs, a species that is used in biomedical research to model humans.Research design and methods GLP-1R distribution and occupancy were measured in pancreas and gastrointestinal tract by ex vivo autoradiography using the GLP-1R-specific radioligand 177Lu-exendin-4 in two groups of pigs, control or bottle-fed an oral glucose load. Positron emission tomography (PET) data from pigs injected with 68Ga-exendin-4 in a previous study were used to retrieve data on biodistribution of GLP-1R in the gastrointestinal tract.Results High homogenous uptake of 177Lu-exendin-4 was found in pancreas, and even higher uptake in areas of duodenum. Low uptake of 177Lu-exendin-4 was found in stomach, jejunum, ileum and colon. During OGTT, there was no increase in plasma GLP-1 concentrations and occupancy of GLP-1Rs was low. The ex vivo autoradiography results were highly consistent with to the biodistribution of 68Ga-exendin-4 in pigs scanned by PET.Conclusion We identified areas with similarities as well as important differences regarding GLP-1R distribution and occupancy in pigs compared with humans. First, there was strong ligand binding in the exocrine pancreas in islets. Second, GLP-1 secretion during OGTT is minimal and GLP-1 might not be an important incretin in pigs under physiological conditions. These findings offer new insights on the relevance of porcine diabetes models.

Long bone fractures are common and sometimes difficult to treat. Autologous bone (AB), bovine bone and calcium phosphates are used to stimulate bone growth with varying results. In the present study, a calcium phosphate cement (CPC) that previously showed promising grafting capabilities was evaluated for the first time in a long bone defect. A radius defect of 20 mm was created in 20 rabbits. The defect was filled by either a hollow CPC implant that had been manufactured as a replica of a rabbit radius through indirect 3D printing, or by particulate AB as control. Defect filling and bone formation was evaluated after 12 weeks by combining micro computed tomography (μCT) and scoring of 3D images, together with histomorphometry and histology. The μCT and histomorphometric evaluations showed a similar amount of filling of the defect (combining graft and bone) between the CPC and AB group, but the scoring of 3D images showed that the filling in the CPC group was significantly larger. Histologically the AB graft could not be distinguished from the new bone. The AB treated defects were found to be composed of more bone than the CPC group, including reorganised cancellous and cortical bone. Both the CPC and AB material was associated with new bone formation, also in the middle of the defect, which could result in closing of the otherwise critically sized gap. This study shows the potential for an indirectly 3D printed implant in guided bone regeneration in critically sized long bone defects. De två första författarna delar förstaförfattarskapetTitle in thesis list of papers: Guided bone tissue regeneration using a hollow calcium phosphate based implant in a critically sized rabbit radius defect

The pig is commonly used in renal transplantation studies since the porcine kidney resembles the human kidney. To meet the requirements of intense caretaking and examination without stress, a 2-week socialisation and training programme was developed. Conventional cross-breed pigs ( n = 36) with high health status were trained for 15 min/day in a four-step training programme before kidney transplantation. The systematic training resulted in calm animals, which allowed for ultrasound examination, blood sampling and urine sampling without restraint. When a 2-methacryloyloxyethyl phosphorylcholine polymer-coated jugular catheter introduced via the auricular vein was used for post-operative blood sampling, clotting was avoided. To assess renal function, urinary output was observed and creatinine and cystatin C were measured; the latter was not found to be useful in recently transplanted pigs. The results presented contribute to the 3Rs (refine, reduce, replace).

An amendment to this paper has been published and can be accessed via the original article.

Objective To compare physiological effects of sufentanil-midazolam with sevoflurane for surgical anaesthesia in medetomidine premedicated rabbits. Study design Prospective, randomized controlled experimental study. Animals Eighteen female Himalayan rabbits, weight 2.1 ± 0.1 kg. Methods Premedication with 0.1 mg kg−1 medetomidine and 5 mg kg−1 carprofen subcutaneously, was followed by intravenous anaesthetic induction with sufentanil (2.3 μg mL−1) and midazolam (0.45 mg mL−1). After endotracheal intubation, anaesthesia was maintained with sufentanil-midazolam (n = 9) or sevoflurane (n = 9). Ovariohysterectomy was performed. Intermittent positive pressure ventilation was performed as required. Physiological variables were studied perioperatively. Group means of physiologic data were generated for different anaesthetic periods. Data were compared for changes from sedation, and between groups by anova . Post-operatively, 0.05 mg kg−1 buprenorphine was administered once and 5 mg kg−1 carprofen once daily for 2–3 days. Rabbits were examined and weighed daily until one week after surgery. Results Smooth induction of anaesthesia was achieved within 5 minutes. Sufentanil and midazolam doses were 0.5 μg kg−1 and 0.1 mg kg−1, during induction and 3.9 μg kg−1 hour−1 and 0.8 mg kg−1 hour−1 during surgery, respectively. End-tidal sevoflurane concentration was 2.1% during surgery. Assisted ventilation was required in nine rabbits receiving sufentanil-midazolam and four receiving sevoflurane. There were no differences between groups in physiologic data other than arterial carbon dioxide. In rabbits receiving sevoflurane, mean arterial pressure decreased pre-surgical intervention, heart rate increased 25% during and after surgery and body weight decreased 4% post-operatively. Post-operative problems sometimes resulted from catheterization of the ear artery. Conclusion Sevoflurane and sufentanil-midazolam provided surgical anaesthesia of similar quality. Arterial blood pressure was sustained during sufentanil-midazolam anaesthesia and rabbits receiving sevoflurane lost body weight following ovariohysterectomy. Mechanical ventilation was required with both anaesthetic regimens. Clinical relevance Anaesthesia with sufentanil-midazolam in medetomidine premedicated healthy rabbits is useful in the clinical and the research setting, as an alternative to sevoflurane.

In connection with bilateral maxillary sinus augmentation, the acute effects of the nonsteroidal anti-inflammatory drug carprofen on facial expressions and long-term effects on bone formation were evaluated in 18 male New Zealand White rabbits. A 10 × 10mm bone window was drilled in the maxilla, the sinus membrane elevated and a titanium mini-implant inserted. One of two test materials was randomly inserted unilaterally and bovine bone chips (control) on the contralateral side in the created space. Rabbits were randomly allocated to receive buprenorphine plus carprofen (n = 9) or buprenorphine plus saline (n = 9) postoperatively. Buprenorphine was administered subcutaneously every 6 h for 3 days in a tapered dose (0.05-0.01 mg/kg) and carprofen (5 mg/kg) or saline administered subcutaneously 1 h before, and daily for 4 days postoperatively. To assess pain, clinical examination, body weight recording and scoring of facial expressions from photos taken before, and 6-13 h after surgery were performed. Twelve weeks after surgery the rabbits were euthanized and sections of maxillary bones and sinuses were analysed with histomorphometry and by qualitative histology. Carprofen had no effect on mean facial expression scores,which increased from 0.0 to 3.6 (carprofen) and 4.3 (saline), of a maximum of 8.0. Neither did carprofen have an effect on bone formation or implant incorporation, whereas the test materials had. In conclusion, treatment with 5mg/kg carprofen once daily for 5 days did not reduce facial expression scores after maxillary sinus augmentation in buprenorphine treated rabbits and did not affect long term bone formation.

Pigs are commonly used in diabetes research due to their many physiological similarities to humans. They are especially useful in imaging procedures because of their large size. However, to achieve imaging procedures the pig must lie completely still, and thus needs to be anaesthetized. Most anaesthetic drugs used in laboratory animals affect carbohydrate metabolism by the inhibition of insulin release. The aim of this pilot study was primarily to develop an anaesthetic protocol for pigs that did not have an effect on blood glucose levels throughout the 3 h of anaesthesia; and secondly, to evaluate the most promising protocol in combination with an oral glucose tolerance test (OGTT). Two anaesthetic protocols were used in four growing pigs. Intravenous propofol infusion caused hyperglycaemia in three out of four pigs within 5–10 min after induction and was therefore excluded. Intravenous infusion with tiletamine, zolazepam and butorphanol (TZB) for 3 h did not affect blood glucose levels. The pigs underwent OGTT twice, once without anaesthesia and once with TZB induction after glucose intake. Anaesthesia during OGTT resulted in a lower area under the curve (AUC) of glucose ( P

The aim of this study was to investigate if a synthetic granular calcium phosphate compound (CPC) and a composite bisphosphonate-linked hyaluronic acid-calcium phosphate hydrogel (HABP·CaP) induced similar or more amount of bone as bovine mineral in a modified sinus lift rabbit model.Eighteen adult male New Zeeland White rabbits, received randomly one of the two test materials on a random side of the face, and bovine mineral as control on the contralateral side. In a sinus lift, the sinus mucosa was elevated and a titanium mini-implant was placed in the alveolar bone. Augmentation material (CPC, HABP·CaP or bovine bone) was applied in the space around the implant. The rabbits were euthanized three months after surgery and qualitative and histomorphometric evaluation were conducted. Histomorphometric evaluation included three different regions of interest (ROIs) and the bone to implant contact on each installed implant.Qualitative assessment (p = .05), histomorphometric evaluations (p = .01), and implant incorporation (p = .05) showed that CPC and bovine mineral induced similar amount of bone and more than the HABP·CaP hydrogel.CPC induced similar amount of bone as bovine mineral and both materials induced more bone than HABP·CaP hydrogel.The CPC is suggested as a synthetic alternative for augmentations in the maxillofacial area.

Eighteen female New Zealand White rabbits (3.9 ± 0.4 kg) were anaesthetized with sufentanil–midazolam by intravenous infusion (SUF–MID, n = 9) or isoflurane (ISO, n = 9) for bilateral creation of an osteochondral defect in the medial femur condyle. Subcutaneous premedication with 0.1 mg/kg medetomidine and anaesthesia induction by intravenous infusion of 1.1 µg/kg sufentanil and 0.2 mg/kg midazolam were identical in both groups. During surgery (60 min), the effects on respiratory and circulatory variables serum lactate, total protein and blood glucose were examined. Intermittent positive pressure ventilation (IPPV) was initiated if apnoea lasted>30 s or if end-tidal CO2 ≥8 kPa. The righting reflex was lost in 3 min. IPPV was necessary during most of the anaesthesia for most of the rabbits. Maintenance doses during surgery were 2.0 µg/kg/h sufentanil and 0.4 mg/kg/h midazolam, and 1.4% isoflurane, respectively. Mean arterial blood pressure (MAP) was higher in group SUF–MID than group ISO during surgery (63 ± 12 vs 50 ± 8 mmHg). In group ISO the heart rate was higher during surgery than before anaesthesia (197 ± 26 vs 158 ± 40 bpm) as was blood glucose (9 ± 2 vs 12 ± 3 mmol/L). Serum lactate levels remained unchanged whereas total protein decreased in both groups. Time to recover from anaesthesia did not differ between groups (20 min). Intravenous sufentanil–midazolam infusion provided surgical anaesthesia with a higher MAP than isoflurane anaesthesia. The protocol can be useful in situations in which gas anaesthesia cannot be used or in animals with limited cardiovascular reserves. However, IPPV is necessary.

Currently used anticoagulants prevent thrombosis but increase bleeding. We show an anticoagulation therapy without bleeding risk based on a plasma protease factor XII function-neutralizing antibody. We screened for antibodies against activated factor XII (FXIIa) using phage display and demonstrated that recombinant fully human antibody 3F7 binds into the FXIIa enzymatic pocket. 3F7 interfered with FXIIa-mediated coagulation, abolished thrombus formation under flow, and blocked experimental thrombosis in mice and rabbits. We adapted an extracorporeal membrane oxygenation (ECMO) cardiopulmonary bypass system used for infant therapy to analyze clinical applicability of 3F7 in rabbits. 3F7 provided thromboprotection as efficiently as heparin, and both drugs prevented fibrin deposition and thrombosis within the extracorporeal circuit. Unlike heparin, 3F7 treatment did not impair the hemostatic capacity and did not increase bleeding from wounds. These data establish that targeting of FXIIa is a safe mode of thromboprotection in bypass systems, and provide a clinically relevant anticoagulation strategy that is not complicated by excess bleeding.

Articular cartilage has a limited capacity for self-repair in adult humans, and methods used to stimulate regeneration often result in re-growth of fibrous cartilage, which has lower durability. No current treatment option can provide complete repair. The possibility of growth factor delivery into the joint for cartilage regeneration after injury would be an attractive treatment option. A full thickness osteochondral defect of 4 mm in diameter and 2 mm deep was created by mechanical drilling in the medial femoral condyle in 20 female adult New Zealand White rabbits. In an attempt to improve regeneration a hyaluronic hydrogel system, with or without bone morphogenetic protein-2 (BMP-2) was delivered intraarticularly. The contralateral joint defect was treated with saline as control. Throughout the study, rabbits were clinically examined and after 12 ( n = 6) or 24 ( n = 9) weeks, the rabbits were euthanized and the joints evaluated by histology. The defects healed with fibrocartilage like tissue, and the filling of the defects ranged from less than 25% to complete. The healing of the defects varied both inter- and intra-group wise. Treatment with hyaluronan gel with or without BMP-2 had no effect on cartilage regeneration compared with controls. Instead, severe ectopic bone formation was found in seven joints treated with BMP-2. In conclusion, the present study shows that neither treatment with hyaluronic gel alone, nor in combination with BMP-2, improves the healing of an induced cartilage defect in rabbits. It further shows that BMP-2 can induce ectopic bone formation, which severely affects the functionality of the joint.

The present work describes the feasibility of a cross-linkable injectable hyaluronan hydrogel for cartilage repair. The hydrogel used is a two-component system based on aldehyde-modified hyaluronan and hydrazide-modified polyvinyl alcohol, which are rapidly cross-linked in situ upon mixing. The in vitro study showed that chondrocytes and mesenchymal cells cultured in the gel form cartilage-like tissue, rich in glycosaminoglycans, collagen type II and aggrecan. In a rabbit animal model the injection of the hydrogel improved the healing of a full-thickness cartilage defect created in the knee as compared to non-treated controls. This rabbit study showed that the regenerated cartilage defects stained more intensely for type II collagen upon treatment with the hydrogel. The hyaluronan-based hydrogel may be used as a delivery vehicle for both growth factors and/or cells for cartilage repair. The in vivo study also indicated that the hydrogel alone has a beneficial effect on cartilage regeneration.

Background Anaesthesia in rabbits is associated with a high mortality rate, compared to that in cats and dogs. Total intravenous anaesthesia (TIVA) with drugs that provide cardiovascular stability and are rapidly metabolised could be of benefit for use in rabbits. The aim was to evaluate cardiorespiratory effects of TIVA with sufentanil-midazolam in eight New Zealand White rabbits. Subcutaneous premedication with medetomidine (0.1 mg/kg BW) was followed by IV administration of a mixture of 2.5 μg/mL sufentanil and 0.45 mg/mL midazolam at a rate of 0.3 mL/kg BW/h for anaesthetic induction. Additionally, intravenous boluses of 0.1 mL of the mixture were administered every 20 s until the righting reflex was lost. Following endotracheal intubation, anaesthesia was maintained for 60 min with an infusion rate adjusted to supress the pedal withdrawal reflex. Air and oxygen (1:2) were delivered at 3 L/min. Physiological variables were recorded before induction and at predefined time points during and after anaesthesia. Results Righting and pedal withdrawal reflexes were lost within 3 and 5 min, respectively. Doses of sufentanil and midazolam were 0.48 μg/kg BW and 0.09 mg/kg BW for induction, and 0.72 μg/kg BW/h and 0.13 mg/kg BW/h for maintenance. Apnoea occurred in two rabbits. Induction of anaesthesia caused a significant increase in heart rate, cardiac output and arterial CO2 partial pressure and a decrease in mean arterial pressure, respiratory rate and pH. Mean time from stopping the infusion to endotracheal extubation was 5 min, and to return of the righting reflex 7 min. Anaesthesia was characterized by induction and recovery without excitation, with muscle relaxation, and absence of the pedal withdrawal reflex. Conclusions TIVA with sufentanil-midazolam provided smooth induction and recovery of anaesthesia in rabbits but with marked hypotension and respiratory depression, requiring mechanical ventilation. Further evaluation is needed to establish if the protocol is useful for rabbits undergoing surgery.