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Selective therapeutic hypothermia (TH) showed promising preclinical results as a neuroprotective strategy in acute ischemic stroke. We aimed to assess safety and feasibility of an intracarotid cooling catheter conceived for fast and selective brain cooling during endovascular thrombectomy in an ovine stroke model. Transient middle cerebral artery occlusion (MCAO, 3 h) was performed in 20 sheep. In the hypothermia group (n = 10), selective TH was initiated 20 minutes before recanalization, and was maintained for another 3 h. In the normothermia control group (n = 10), a standard 8 French catheter was used instead. Primary endpoints were intranasal cooling performance (feasibility) plus vessel patency assessed by digital subtraction angiography and carotid artery wall integrity (histopathology, both safety). Secondary endpoints were neurological outcome and infarct volumes. Computed tomography perfusion demonstrated MCA territory hypoperfusion during MCAO in both groups. Intranasal temperature decreased by 1.1 °C/3.1 °C after 10/60 minutes in the TH group and 0.3 °C/0.4 °C in the normothermia group (p Selective TH was feasible and safe. However, a larger number of subjects might be required to demonstrate efficacy.

Background Regarding the overall inadequate results after cardiopulmonary resuscitation, the development of new treatment concepts is urgently needed. Controlled Automated Reperfusion of the whoLe body (CARL) represents a therapy bundle to control the conditions of reperfusion and the composition of the reperfusate after cardiac arrest (CA). The aim of this study was to investigate the plasma expander’s role in the CARL priming solution and examine its mechanism of action. Methods Viscosity, osmolality, colloid osmotic pressure (COP), pH and calcium binding of different priming solutions were measured in vitro and compared to in vivo data. N = 16 pigs were allocated to receive CARL following 20 min of untreated CA with either human albumin 20% (HA, N = 8) or gelatin polysuccinate 4% (GP, N = 8). Blood gas analyses were performed during the first hour of reperfusion and catecholamine and fluid requirements were recorded. Neurological outcome was assessed by neurological deficit scoring (NDS) on the seventh day. Results In vitro, addition of HA to the CARL priming solution resulted in higher COP and higher calcium-binding than GP. In vivo, treatment with HA led to greater reduction of ionized calcium and higher extracorporeal flows within the first 30 min of reperfusion with no difference in catecholamine support and fluid requirement. Seven-day survival of 75% with no difference in NDS was observed in both groups. Conclusions Our data show that the plasma expander in the CARL priming solution has a significant effect on the initial reperfusate and can potentially influence the course of resuscitation. However, seven-day survival and NDS did not differ between groups.

Introduction: An ultra-thin, fracture-resistant and bioresorbable stent may be advantageous for provisional stenting in vessel bifurcations, if catheter passage and side-branch post-dilatation is facilitated to prevent a 'stent jail' by struts obstructing the orifice of a major side branch.Material and methods: We studied a highly radiopaque, slowly bioresorbable zinc alloy stent characterized by a novel design of a radiopaque-marked region of ultra-thin struts in the center of the stent. The stent is characterized by an extended range flexibility and high fracture resistance. Zn-stents and Zn-drug eluting stents (DES) were implanted opposite to rigid Nitinol stents into both femoral artery bifurcations of 21 juvenile pigs, followed for one and three months and studied by angiography and histomorphometry.Results and conclusion: Bare Zn-stents with thinner stent struts showed less neointimal hyperplasia compared to Zn-stents with thicker struts Neointimal formation was further reduced by 12% in Zn-alloy DES. Both, bare Zn-stents and Zn-DES, can be precisely positioned into the femoral artery bifurcation, allowing easy balloon catheter passage through the very thin strut mesh. Side branch orifices remained open after Zn-stent deployment without stent jailing. No stent fractures or particles emboli occurred after the deployment. A Zn-stent with ultra-thin center struts may be useful for provisional stenting in vessel bifurcations.

OBJECTIVES Existing surgical sealants fail to combine design requirements, such as sealing performance, on-demand activation and biocompatibility. The aim of this study was to compare the effectiveness and safety of the SETALIUM™ Vascular Sealant (SVS), a novel, on-demand activatable sealant, with the commercial sealant, BioGlue®, for the repair of vascular defects. METHODS In an in vivo porcine model, the use of SVS was compared with BioGlue, for sealing 2-mm defects of the carotid artery and jugular vein. Animals were followed for 7 days and 5 weeks (each time point and per experimental group, n = 4), respectively. The degree of stenosis and flow velocity was determined, and the local tissue response was evaluated. RESULTS In vivo incision closure succeeded in all cases, and SVS was superior in clinical usability, enabled by its on-demand activation. Unlike BioGlue, SVS use did not induce stenosis and was associated with physiological blood flow in all cases. Moreover, closure with SVS was associated with a low inflammatory reaction and no thrombus formation or intima proliferation, in contrast to BioGlue. CONCLUSIONS SVS demonstrated effective and rapid sealing of 2-mm vascular defects, with favourable biocompatibility compared to BioGlue. Thus, SVS seems to be an effective and safe vascular sealant.

Supplemental Digital Content is available in the text., Objectives: Lung-protective ventilation for acute respiratory distress syndrome aims for providing sufficient oxygenation and carbon dioxide clearance, while limiting the harmful effects of mechanical ventilation. “Flow-controlled ventilation”, providing a constant expiratory flow, has been suggested as a new lung-protective ventilation strategy. The aim of this study was to test whether flow-controlled ventilation attenuates lung injury in an animal model of acute respiratory distress syndrome. Design: Preclinical, randomized controlled animal study. Setting: Animal research facility. Subjects: Nineteen German landrace hybrid pigs. Intervention: Flow-controlled ventilation (intervention group) or volume-controlled ventilation (control group) with identical tidal volume (7 mL/kg) and positive end-expiratory pressure (9 cm H2O) after inducing acute respiratory distress syndrome with oleic acid. Measurements and Main Results: Pao2 and Paco2, minute volume, tracheal pressure, lung aeration measured via CT, alveolar wall thickness, cell infiltration, and surfactant protein A concentration in bronchoalveolar lavage fluid. Five pigs were excluded leaving n equals to 7 for each group. Compared with control, flow-controlled ventilation elevated Pao2 (154 ± 21 vs 105 ± 9 torr; 20.5 ± 2.8 vs 14.0 ± 1.2 kPa; p = 0.035) and achieved comparable Paco2 (57 ± 3 vs 54 ± 1 torr; 7.6 ± 0.4 vs 7.1 ± 0.1 kPa; p = 0.37) with a lower minute volume (6.4 ± 0.5 vs 8.7 ± 0.4 L/min; p < 0.001). Inspiratory plateau pressure was comparable in both groups (31 ± 2 vs 34 ± 2 cm H2O; p = 0.16). Flow-controlled ventilation increased normally aerated (24% ± 4% vs 10% ± 2%; p = 0.004) and decreased nonaerated lung volume (23% ± 6% vs 38% ± 5%; p = 0.033) in the dependent lung region. Alveolar walls were thinner (5.5 ± 0.1 vs 7.8 ± 0.2 µm; p < 0.0001), cell infiltration was lower (20 ± 2 vs 32 ± 2 n/field; p < 0.0001), and normalized surfactant protein A concentration was higher with flow-controlled ventilation (1.1 ± 0.04 vs 1.0 ± 0.03; p = 0.039). Conclusions: Flow-controlled ventilation enhances lung aeration in the dependent lung region and consequently improves gas exchange and attenuates lung injury. Control of the expiratory flow may provide a novel option for lung-protective ventilation.

Temporary middle cerebral artery occlusion (MCAO) in sheep allows modeling of acute large vessel occlusion stroke and subsequent vessel recanalization. However, rapid and precise imaging-based assessment of vessel occlusion and the resulting perfusion deficit during MCAO still represents an experimental challenge. Here, we tested feasibility and suitability of a strategy for MCAO verification and perfusion deficit assessment. We also compared the extent of the initial perfusion deficit and subsequent lesion size for different MCAO durations. The rete mirabile prevents reliable vascular imaging investigation of middle cerebral artery filling status. Hence, computed tomography perfusion imaging was chosen for indirect confirmation of MCAO. Follow-up infarct size evaluation by diffusion-weighted magnetic resonance imaging revealed fluctuating results, with no apparent relationship of lesion size with MCAO at occlusion times below 4 h, potentially related to the variable collateralization of the MCA territory. This underlines the need for intra-ischemic perfusion assessment and future studies focusing on the correlation between perfusion deficit, MCAO duration, and final infarct volume. Temporary MCAO and intra-ischemic perfusion imaging nevertheless has the potential to be applied for the simulation of novel recanalization therapies, particularly those that aim for a fast reperfusion effect in combination with mechanical thrombectomy in a clinically realistic scenario.\ud \ud

Medical brain implants for closed-loop interaction with the cerebral cortex promise new treatment options for brain disorders, and thus great efforts are being made to develop devices for long-term application. Closed-loop interaction can be implemented using electrophysiological recording techniques, and can be used to modulate local cortical activity or long-range functional connectivity. In a case study performed in sheep chronically implanted with a novel micro-electrocorticography-based device, we show that (1) open-loop single-pulse electrical stimulation (SPES) elicited the well-known cortico-cortical evoked potentials (CCEPs), and (2) closed-loop repetitive-pulse electrical stimulation (RPES) elicited specific cortico-cortical spectral responses (CCSRs). CCSRs were spatially focalized in the gamma band, compared with beta band independent of RPES frequency. The topography of CCSRs was different compared with CCEPs, suggesting that CCEPs and CCSRs capture different aspects of cortico-cortic...

Metallic Zn alloys have recently gained interest as potential candidates for developing platforms of bioresorbable vascular stents (BVS). Previous studies revealed that Mg alloys used for BVS can degrade too early, whereas PLLA materials may fail to provide effective scaffolding properties. Here we report on results of a new bioresorbable, metallic stent made from a Zn-Ag alloy studied in a porcine animal model of thrombosis and restenosis. While the tensile strength (MPa) of Zn-3Ag was higher than that of PLLA and resembled Mg's (WE43), fracture elongation (%) of Zn-3Ag was much greater (18-fold) than the PLLA's or Mg alloy's (WE43). Zn-3Ag exposed to HAoSMC culture medium for 30 days revealed degradation elements consisting of Zn, O, N, C, P, and Na at a 6 nm surface depth. Platelet adhesion rates and blood biocompatibility did not differ between Zn-3Ag, PLLA, Mg (WE43), and non-resorbable Nitinol (NiTi) stent materials. Balloon-expandable Zn-3Ag alloy BVS implanted into iliofemoral arteries of 15 juvenile domestic pigs were easily visible fluoroscopically at implantation, and their bioresorption was readily detectable via X-ray over time. Histologically, arteries with Zn-3Ag BVS were completely endothelialized, covered with neointima, and were patent at 1, 3, and 6 months follow-up with no signs of stent thrombosis. Zn-3Ag alloy appears to be a promising material platform for the fabrication of a new generation of bioresorbable vascular stents.

The number of implantable bidirectional neural interfaces available for neuroscientific research applications is still limited, despite the rapidly increasing number of customized components. We previously reported on how to translate available components into ”ready-to-use” wireless implantable systems utilizing components off-the-shelf (COTS). The aim of the present study was to verify the viability of a micro-electrocorticographic ($\mu $ECoG) device built by this approach. Functionality for both neural recording and stimulation was evaluated in an ovine animal model using acoustic stimuli and cortical electrical stimulation, respectively. We show that auditory evoked responses were reliably recorded in both time and frequency domain and present data that demonstrates the cortical electrical stimulation functionality. The successful recording of neuronal activity suggests that the device can compete with existing implantable systems as a neurotechnological research tool.

In contrast to conventional mandatory ventilation, a new ventilation mode, expiratory ventilation assistance (EVA), linearises the expiratory tracheal pressure decline.We hypothesised that due to a recruiting effect, linearised expiration oxygenates better than volume controlled ventilation (VCV). We compared the EVA with VCV mode with regard to gas exchange, ventilation volumes and pressures and lung aeration in a model of peri-operative mandatory ventilation in healthy pigs.Controlled interventional trial.Animal operating facility at a university medical centre.A total of 16 German Landrace hybrid pigs.The lungs of anaesthetised pigs were ventilated with the EVA mode (n=9) or VCV (control, n=7) for 5 h with positive end-expiratory pressure of 5 cmH2O and tidal volume of 8 ml kg. The respiratory rate was adjusted for a target end-tidal CO2 of 4.7 to 6 kPa.Tracheal pressure, minute volume and arterial blood gases were recorded repeatedly. Computed thoracic tomography was performed to quantify the percentages of normally and poorly aerated lung tissue.Two animals in the EVA group were excluded due to unstable ventilation (n=1) or unstable FiO2 delivery (n=1). Mean tracheal pressure and PaO2 were higher in the EVA group compared with control (mean tracheal pressure: 11.6 ± 0.4 versus 9.0 ± 0.3 cmH2O, P 0.001 and PaO2: 19.2 ± 0.7 versus 17.5 ± 0.4 kPa, P = 0.002) with comparable peak inspiratory tracheal pressure (18.3 ± 0.9 versus 18.0 ± 1.2 cmH2O, P 0.99). Minute volume was lower in the EVA group compared with control (5.5 ± 0.2 versus 7.0 ± 1.0 l min, P = 0.02) with normoventilation in both groups (PaCO2 5.4 ± 0.3 versus 5.5 ± 0.3 kPa, P 0.99). In the EVA group, the percentage of normally aerated lung tissue was higher (81.0 ± 3.6 versus 75.8 ± 3.0%, P = 0.017) and of poorly aerated lung tissue lower (9.5 ± 3.3 versus 15.7 ± 3.5%, P = 0.002) compared with control.EVA ventilation improves lung aeration via elevated mean tracheal pressure and consequently improves arterial oxygenation at unaltered positive end-expiratory pressure (PEEP) and peak inspiratory pressure (PIP). These findings suggest the EVA mode is a new approach for protective lung ventilation.

Blood collection is a common experimental, procedure for which there are many different methods, each with its own advantages and disadvantages. Researchers should use methods that minimize pain, suffering, distress and lasting harm to animals while meeting study requirements. The authors evaluated stress, activity and tissue damage in BALB/c01aHsd mice after collecting blood using one of six methods: retrobulbar bleeding with thin or thick capillaries, tail vein bleeding, saphenous vein bleeding, facial vein bleeding or jugular vein bleeding. The authors compared in-cage activity, corticosterone concentration and performance in open-field tests between treatment groups and collected histologic samples at 1 h, 3 d and 14 d after bleeding. Mice that underwent retrobulbar bleeding with a thick capillary had a smaller change in corticosterone concentration and higher in-cage activity immediately after blood collection, whereas mice that underwent jugular vein bleeding had a greater change in corticosterone concentration and lower in-cage activity and open-field activity. Mice that underwent saphenous vein bleeding had a high incidence of histological change at 1 h, 3 d and 14 d after blood collection, but few indicators of histological change were present in other groups at 14 d after blood collection. These results suggest that, when collecting a small volume of blood, retrobulbar bleeding with a thick capillary and without anesthesia causes the least stress in mice, whereas jugular vein bleeding and facial vein bleeding cause the most stress and saphenous vein bleeding causes the most lasting damage in mice.

PURPOSE Classic tissue engineering consists of three components: scaffold, cells, and growth or differentiation factors. Currently, expensive bone morphogenetic proteins are the most common substance used for hard tissue regeneration. An alternative could be gamma-aminobutyric acid/lactam (GABA-lactam) analogs. MATERIALS AND METHODS The effects of gabapentin-lactam, cis- and trans-8-tertbutyl-GABA-pentinlactam (trans-TB-GBP-L), and phenyl-GABA-lactam were tested in this study on ovine mesenchymal stem cell (MSC) proliferation. MSCs were selected from bone marrow aspirate concentrate by plastic adherence and amplified. Aliquots of the cells were incubated in medium, with four different concentrations of the GABA-lactam analogs dissolved in dimethyl sulfoxide. Cells in medium with and without dimethyl sulfoxide served as controls. Cell proliferation was tested with a nonradioactive assay. Before and after GABA-lactam analog influence, the MSC character was evaluated by the ability of the cells to differentiate into osteoblasts, chondrocytes, and adipocytes. RESULTS Proliferation was significantly increased under the influence of the analogs, depending on their concentration. MSCs cultured in 1 nmol/L trans-TB-GBP-L showed the highest proliferation rate. The MSC character was not altered. CONCLUSIONS GABA-lactam analogs could be suited to stimulate MSC proliferation for tissue engineering applications. Further in vivo studies are necessary to evaluate the possible clinical potential of GABA-lactam analogs for hard tissue regeneration.

This study was aimed at measuring shear moduli in vivo in mechanically ventilated rats and comparing them to global lung mechanics. Wistar rats ( n = 28) were anesthetized, tracheally intubated, and mechanically ventilated in supine position. The animals were randomly assigned to the healthy control or the lung injury group where lung injury was induced by bronchoalveolar lavage. The respiratory system elastance Ers was analyzed based on the single compartment resistance/elastance lung model using multiple linear regression analysis. The shear modulus (G) of alveolar parenchyma was studied using a newly developed endoscopic system with adjustable pressure at the tip that was designed to induce local mechanostimulation. The data analysis was then carried out with an inverse finite element method. G was determined at continuous positive airway pressure (CPAP) levels of 15, 17, 20, and 30 mbar. The resulting shear moduli of lungs in healthy animals increased from 3.3 ± 1.4 kPa at 15 mbar CPAP to 5.8 ± 2.4 kPa at 30 mbar CPAP ( P = 0.012), whereas G was ∼2.5 kPa at all CPAP levels for the lung-injured animals. Regression analysis showed a negative correlation between G and relative Ers in the control group ( r = −0.73, P = 0.008 at CPA P = 20 mbar) and no significant correlation in the lung injury group. These results suggest that the locally measured G were inversely associated with the elastance of the respiratory system. Rejecting the study hypothesis the researchers concluded that low global respiratory system elastance is related to high local resistance against tissue deformation.

Objectives: In mechanical ventilation, normoventilation in terms of PCO2 can be achieved by titration of the respiratory rate and/or tidal volume. Although a linear relationship has been found between changes in respiratory rate and resulting changes in end-tidal cO2 (△PetCO2) as well as between changes in respiratory rate and equilibration time (teq) for mechanically ventilated patients without lung injury, it is unclear whether a similar relationship holds for acute lung injury or altered hemodynamics. Design: We performed a prospective randomized controlled animal study of the change in PetCO2 with changes in respiratory rate in a lung-healthy, lung-injury, lung-healthy + altered hemodynamics, and lung-injury + altered hemodynamics pig model. Setting: University research laboratory. Subjects: Twenty mechanically ventilated pigs. Interventions: Moderate lung injury was induced by injection of oleic acid in 10 randomly assigned pigs, and after the first round of measurements, cardiac output was increased by approximately 30% by constant administration of noradrenalin in both groups. Measurements and Main Results: We systematically increased and decreased changes in respiratory rate according to a set protocol: +2, -4, +6, -8, +10, -12, +14 breaths/min and awaited equilibration of Petco2. We found a linear relationship between changes in respiratory rate and △PetCO2 as well as between changes in respiratory rate and teq. A two-sample t test resulted in no significant differences between the lung injury and healthy control group before or after hemodynamic intervention. Furthermore, exponential extrapolation allowed prediction of the new PetCO2 equilibrium and teq after 5.7 ± 5.6 min. Conclusions: The transition between PetCO2 equilibria after changes in respiratory rate might not be dependent on moderate lung injury or cardiac output but on the metabolic production or capacity of cO2 stores. Linear relationships previously found for lung-healthy patients and early prediction of PetCO2 equilibration could therefore also be used for the titration of respiratory rate on the PetCO2 for a wider range of pathologies by the physician or an automated ventilation system.

To evaluate the viability and biocompatibility of a novel, patented bioadhesive system for intrarenal embedding and retrieval of residual fragments after endoscopic lithotripsy. Complete stone clearance via active removal of residual fragments (RF) after intracorporeal laser lithotripsy may be time-consuming and fail in many cases. Therefore, the novel adhesive has been developed and evaluated for the first time in an in vivo pig model in the present work. Four female domestic pigs underwent flexible ureteroscopy (RIRS) or percutaneous nephrolithotomy (PNL) under general anesthesia (8 kidneys, 4 × RIRS, 4 × PNL) evaluating the bioadhesive system. Interventions: RIRS without adhesive system (sham procedure, kidney I); 3 × RIRS using the bioadhesive system (kidneys II–IV); and 4 × PNL using the bioadhesive system (V–VIII). We endoscopically inserted standardized human stone probes followed by comminution using Ho:YAG lithotripsy. The bioadhesive (kidney II–VIII) was then applied and the adhesive-stone fragment complex extracted. After nephrectomy, all kidneys were evaluated by two independent, blinded pathologists. Endpoints were the procedure’s safety and adhesive system’s biocompatibility. We observed no substantial toxic effects. We were able to embed and remove 80–90% of fragments. However, because of the pig’s hampering pyelocaliceal anatomy, a quantified, proportional assessment of the embedded fragments was compromised. For the first time, we demonstrated the proven feasibility and safety of this novel bioadhesive system for embedding and endoscopically removing small RF in conjunction with a lack of organ toxicity in vivo.

Objective To compare the efficacy of the new reusable vessel-sealing device MarSeal (KLS Martin, Tuttlingen, Germany) with the conventional standard disposable LigaSure device (Covidien-Valleylab, Boulder, CO) in an in vivo animal model. Design Prospective animal study. Setting Center of Experimental Surgery at a university hospital. Animals Thirteen sheep. Intervention(s) The carotid and femoral arteries were dissected bilaterally and sealed randomly with MarSeal unilaterally and consecutively with LigaSure contralaterally in vivo. Afterward the burst pressure was determined for each artery. Main Outcome Measure(s) Sealing time, failure rate, and burst pressure. Result(s) The mean diameter of all arteries sealed did not differ significantly between the two groups (MarSeal 5.40 mm vs. LigaSure 5.35 mm). The mean sealing time was significantly shorter with use of the reusable device (MarSeal 5.2 seconds vs. LigaSure 9.1 seconds). We did not find a significant difference in sealing failure rates between the groups (MarSeal 7.0% vs. LigaSure 9.1%). In addition, analysis of mean burst pressure did not reveal a significant difference between the different devices (MarSeal 429 mm Hg vs. LigaSure 484 mm Hg). There was no significant difference with respect to lateral thermal damage (MarSeal 0.91 cm vs. LigaSure 0.93 cm). Conclusion(s) In our in vivo animal study, the new reusable MarSeal device appears to be equivalently effective for vessel sealing when compared with the conventional disposable LigaSure device.

Several studies have reported certain bone morphogenic proteins (BMPs) to have positive effects on bone generation. Although some investigators have studied the effects of human recombinant BMP (rhBMP-2) in sinus augmentation in sheep, none of these studies looked at the placement of implants at the time of sinus augmentation. Furthermore, no literature could be found to report on the impact that different implant systems, as well as the positioning of the implants had on bone formation if rhBMP-2 was utilized in sinus-lift procedures.The aim of this study was to compare sinus augmentation with rhBMP-2 on a poly-d, l-lactic-co-glycolic acid gelatine (PLPG) sponge with sinus augmentation with autologous pelvic cancellous bone in the maxillary sinus during the placement of different dental implants.Nine adult female sheep were submitted to bilateral sinus-floor elevation. In one side (test group) the sinus lift was performed with rhBMP-2 on a PLPG-sponge, while the contralateral side served as the control by using cancellous bone from the iliac crest. Three different implants (Bränemark(®), 3i(®) and Straumann(®)) were inserted either simultaneously with the sinus augmentation or as a two staged procedure 6 weeks later. The animals were sacrificed at 6 and 12 weeks for histological and histomorphometrical evaluations during which bone-to-implant contact (BIC) and bone density (BD) were evaluated.BD and BIC were significantly higher at 12 weeks in the test group if the implants were placed at the time of the sinus lift (p0.05). No difference was observed between the different implant systems or positions.The use of rhBMP-2 with PLPG-sponge increased BIC as well as BD in the augmented sinuses if compared to autologous bone. Different implant systems and positions of the implants had no effect on BIC or BD.

Our aim was to compare the osteogenic potential of mononuclear cells harvested from the iliac crest combined with bovine bone mineral (BBM) (experimental group) with that of autogenous cancellous bone alone (control group). We studied bilateral augmentations of the sinus floor in 6 adult sheep. BBM and mononuclear cells (MNC) were mixed and placed into one side and autogenous bone in the other side. Animals were killed after 8 and 16 weeks. Sites of augmentation were analysed radiographically and histologically. The mean (SD) augmentation volume was 3.0 (1.0) cm 3 and 2.7 (0.3) cm 3 after 8 and 16 weeks in the test group, and 2.8 (0.3) cm 3 (8 weeks) and 2.8 (1.2) cm 3 (16 weeks) in the control group, respectively. After 8 weeks, histomorphometric analysis showed 24 (3)% BBM, and 19 (11)% of newly formed bone in the test group. The control group had 20 (13%) of newly formed bone. Specimens after 16 weeks showed 29 (12%) of newly formed bone and 19 (3%) BBM in the test group. The amount of newly formed bone in the control group was 16 (6%). The results show that mononuclear cells, including mesenchymal stem cells, in combination with BBM as the biomaterial, have the potential to form bone.

Doxorubicin causes a chronic cardiomyopathy in which genetic and functional lesions of mitochondria accumulate in the long-term and explain in part the delayed onset of heart dysfunction. DOXO-EMCH a 6-maleimidocaproyl hydrazone derivative of doxorubicin, is an albumin binding prodrug which has entered clinical trials because of its superior antitumor and toxicological profile. In the present work, we examined the chronic cardiotoxicity of DOXO-EMCH in direct comparison with doxorubicin. Rats (11 weeks of age) were treated with intravenous doxorubicin (0.8 mg/kg weekly for 7 weeks), an equimolar dose of DOXO-EMCH (1.1 mg/kg), or with 3.3 mg/kg of DOXO-EMCH. Controls received saline. Animals were euthanized at 48th week. Rats exposed to doxorubicin had a severe clinical, and histopathological cardiomyopathy with depressed myocardial activity of cytochrome c-oxidase (COX, 26% of controls), reduced expression of the mtDNA-encoded COX II subunit, decreased mtDNA copy numbers (46% of controls), and high levels of malondialdehyde and superoxide (787% of controls). All parameters were highly correlated with myocardial damage. Both DOXO-EMCH groups did not differ from controls with regard to clinical symptomatology, mortality and mitochondrial enzymes, although the myocardia of the high-dose group had slightly increased histopathological abnormalities, depressed mtDNA copies (74% of controls) and elevated superoxide levels (347% of controls). Doxorubicin-exposed hearts and to a lesser extent the myocardia of both DOXO-EMCH groups contained mtDNA-deletions. In summary both DOXO-EMCH doses were superior over doxorubicin with respect to clinical and histopathological evidence of cardiomyopathy, myocardial COX-activity, COX II expression, mtDNA-content, mtDNA mutation loads and superoxide production in rats.

Polymer stent coatings may not be suitable for drug elution because of inherent proinflammatory effects. A previous study suggested a beneficial effect of a stent eluting tacrolimus from a nanoporous ceramic aluminum oxide coating in a rabbit restenosis model. We investigated whether this stent is effective in preventing in-stent restenosis in a porcine restenosis model. Thirty-four juvenile swine underwent balloon overstretch injury and were subjected to implantation of either stainless steel (bare) stents, bare stents coated with nanoporous aluminum oxide alone, and coated stents eluting 50 and 180 mug of tacrolimus (FK506). In-stent restenosis was quantified at 1 and 3 months after stent placement by histomorphometry. A significant increase of neointimal hyperplasia was noted with the stents coated with aluminum oxide alone compared with bare stents (2.92 +/- 1.02 and 1.38 +/- 0.51 mm(2), respectively; P < 0.02). In all arteries containing coated stents, particle debris was found in the media and neointima, resulting in augmented vascular inflammation. In the group of stents coated with aluminum oxide, FK506 elution at a dose 180 mug reduced neointimal hyperplasia vs. no drug elution (1.66 +/- 0.49 vs. 2.92 +/- 1.02 mm(2); 180 mug vs. ceramic alone; P < 0.03). At a dose of 50 mug stent-based delivery of FK506, no reduction of neointimal hyperplasia was found (2.88 +/- 1.31 and 2.92 +/- 1.02 mm(2), respectively; P = NS; FK506 vs. ceramic alone). In summary, particle debris shed from a drug-eluting aluminum oxide coating of a stainless steel stent counteracts potential antiproliferative effects of stent-based tacrolimus delivery in a porcine model of restenosis. We propose that stent coatings eluting drugs need to be routinely tested for being tightly anchored into the stent surface. Alternatively, omission of any coating used as a drug reservoir may eliminate inflammatory particle debris after placement of drug-eluting stents.

We investigated the effects of recruitment maneuvers on subpleural alveolar area in healthy rats. 36 mechanically ventilated rats were allocated to either ZEEP-group or PEEP – 5 cmH2O – group. The subpleural alveoli were observed using a transthoracal endoscopic imaging technique. Two consecutive low-flow maneuvers up to 30 cmH2O peak pressure each were performed, interrupted by 5 s plateau phases at four different pressure levels. Alveolar area change at maneuver peak pressures and during the plateau phases was calculated and respiratory system compliance before and after the maneuvers was analyzed. In both groups alveolar area at the second peak of the maneuver did not differ significantly compared to the first peak. During the plateau phases there was a slight increase in alveolar area. After the maneuvers, compliance increased by 30% in ZEEP group and 20% in PEEP group. We conclude that the volume insufflated by the low-flow recruitment maneuver is distributed to deeper but not to subpleural lung regions.

BACKGROUND Neutrophils are of great importance for the host's defense against invading organisms. Granulocyte colony-stimulating factor (G-CSF) has been used to augment both the neutrophil number and function, and its prophylactic administration has proved beneficial in animal models of sepsis. However, pretreatment with G-CSF is not practical under clinical conditions. We therefore investigated the effect of recombinant human (rh)G-CSF, administered only after infection, on the survival rate as well as the hemodynamic and cytokine response of the animals. METHODS Chronically catheterized conscious pigs were challenged with Pseudomonas aeruginosa (8 x 10(7) colony-forming units kg(-1) x h(-1) for 120 h (control group, n = 10). Animals in the G-CSF group (n = 7) also received rhG-CSF (5 microg kg(-1) x day(-1)), the first dose being given 3 h after beginning bacterial infusion. RESULTS The mortality rate was 50% (5/10) and 29% (2/7) in the control and G-CSF groups, respectively (p = NS, control vs. G-CSF group). Fever, severe pulmonary hypertension, and a hyperdynamic response were recorded in all of the animals. In spite of a prompt and significant recovery from the initial leukopenia (p < .05 vs. control group), the animals of the G-CSF group showed no significant differences in the parameters investigated from those of the controls. Compared with the survivors, the interleukin-1 receptor antagonist was markedly elevated in all nonsurvivors after 6 h of sepsis (p < .05). CONCLUSIONS These data suggest that treatment with rhG-CSF after the onset of bacterial sepsis might not significantly improve the chances of survival for non-neutropenic patients.

The effects of a rapid increase in inspired desflurane concentration on systemic haemodynamics and plasma catecholamines were studied in seven pigs (22-30 kg). Following premedication (flunitrazepam 0.4 mg/kg i.m.), anaesthesia was induced (propofol 2.5 mg/kg i.v., vecuronium 0.2 mg/kg i.v.), the trachea orally intubated, and ventilation controlled. Anaesthesia was maintained with N2O/O2 (70%/30%), propofol (50 μg/kg/min), desflurane 12% end-tidal concentration), and vecuronium (0.3 mg/kg/h). After cannulation of both femoral arteries for subsequent simultaneous systemic pressure measurements and blood sampling for determination of epinephrine (E) and norepinephrine (NE) plasma levels, N2O and propofol were discontinued, and FiO2 and end-tidal concentration of desflurane increased to >0.9 and 3%, respectively. Forty minutes later, the inspired concentration of desflurane was abruptly increased to 15%. Mean arterial pressure (MAP), heart rate (HR), and plasma concentrations of E and NE were determined before and 1, 2, 4, 8, 16, and 32 min after increasing the desflurane concentration. Plasma concentrations of E and NE were determined by high performance liquid chromatography (HPLC) with electrochemical detection. Data were analysed by repeated measures ANOVA (significance level P

OBJECTIVES:: Although global respiratory mechanics are usually used to determine the settings of mechanical ventilation, this approach does not adequately take into account alveolar mechanics. However, it should be expected that the ventilatory condition (quasi-static vs. dynamic) and lung condition (noninjured vs. injured) affect alveolar mechanics in a clinically relevant way. Accordingly, the aim of this study was to investigate alveolar mechanics during quasi-static and dynamic ventilatory maneuvers in noninjured and injured lungs. We hypothesized that alveolar mechanics vary with ventilatory and lung conditions. DESIGN:: Prospective animal study. SETTING:: Animal research laboratory. SUBJECTS:: Male Wistar rats. INTERVENTIONS:: Alveolar mechanics (derived from alveolar size and airway pressure) were determined in noninjured (n = 9) and in lungs lavaged with saline (n = 8) at quasi-static (low flow at a peak pressure of 40 cm H2O) and dynamic ventilatory maneuvers (increase and decrease in positive end-expiratory pressure from 0 to 15 and back to 0 cm H2O in steps of 3 cm H2O). Alveoli were recorded endoscopically and alveolar mechanics were extracted using automated tracking of alveolar contours. MEASUREMENTS AND MAIN RESULTS:: The increase in alveolar size during quasi-static maneuvers was significantly greater than during dynamic maneuvers in noninjured (mean difference 18%, p < 0.001) but not in injured lungs (mean difference 3%, p = 0.293). During dynamic maneuvers, slope of the intratidal alveolar pressure/area curve (reflecting distensibility) decreased with increasing positive end-expiratory pressure (p = 0.001) independent of lung condition (noninjured and injured lungs). In contrast, independent of positive end-expiratory pressure but dependent on lung condition, the maximal tidal change in alveolar size was greater by an average of 40% in injured compared with noninjured lungs (p = 0.028). CONCLUSIONS:: Alveolar mechanics during mechanical ventilation differed between quasi-static and dynamic conditions and varied with lung condition. Our data thus confirm that analysis of respiratory system mechanics under dynamic conditions is preferable to analysis during static conditions.

In an experimental study laparoscopic partial liver resection with an ultrasonic dissector was evaluated. Eight domestic pigs with a body weight of approximately 25kg were operated using an ultrasonic dissector during temporary occlusion of the hepatoduodenal ligament (Pringle manoeuvre). Peripheral parts of the liver were resected. Haemostatis was accomplished using electro-coagulation for smaller vessels and titan-clips for larger ones. The same techniques were used for bile duct ligation. One animal died during surgery from undetected bleeding within the lesser sac, which was attributed to the Pringle manoeuvre. The postoperative course of the other animals was uneventful. Three weeks after the initial operation, the animals underwent laparoscopy to evaluate the result. Laparoscopic partial liver resection can be performed using an ultrasonic dissector. The line of resection is determined by the position of the trocars. The combination of electro-coagulation of delicate and clipping of larger blood ves...

Over the last decade tissue engineering has emerged as a key factor in bone regeneration within the field of cranio-maxillofacial surgery. Despite this in vivo analysis of tissue-engineered-constructs to monitor bone rehabilitation are difficult to conduct. Novel high-resolving flat-panel based volume CTs (fp-VCT) are increasingly used for imaging bone structures. This study compares the potential value of novel fp-VCT with conventional multidetector CT (MDCT) based on a sheep sinus floor elevation model. Calcium-hydroxyapatite reinforced collagen scaffolds were populated with autologous osteoblasts and implanted into sheep maxillary sinus. After 8, 16 and 24 weeks MDCT and fp-VCT scans were performed to investigate the volume of the augmented area; densities of cancellous and compact bone were assessed as comparative values. fp-VCT imaging resulted in higher spatial resolution, which was advantageous when separating closely related anatomical structures (i.e. trabecular and compact bone, biomaterials). Fp-VCT facilitated imaging of alterations occurring in test specimens over time. fp-VCTs therefore displayed high volume coverage, dynamic imaging potential and superior performance when investigating superfine bone structures and bone remodelling of biomaterials. Thus, fp-VCTs may be a suitable instrument for intraoperative imaging and future in vivo tissue-engineering studies.

Knitted flexible tantalum stents proved to be a valuable adjunct to percutaneous transluminal angiplasty (PTA) in the case of insufficient PTA results, and their use was established in the distal aorta, the iliac, the femoro-popliteal, the renal, and the coronary arteries. Recently, long arterial occlusions were defined as new indications for primary stenting; stent indications were further extended to the subclavian, the carotid, and the splanchnic arteries. Due to higher incidence of acute and late complications after stent treatment of small diameter arteries, patients have to be selected thoroughly. Newly designed drug-releasing stents tested in animal experiments promised to be suitable to diminish the incidence of late restenosis due to intinal hyperplasia, thus providing better long-term patency.

We investigated the effects of intra-abdominal pressure on respiratory system compliance at different PEEP levels. 20 ventilated rats underwent four pressure levels (7, 9, 11, 13 mm Hg) of helium pneumoperitoneum and were allocated to one of the four PEEP groups (0, 3, 6 and 9 cm H(2)O). From the expiratory pressure-volume curve the mathematical inflection point (MIP) was calculated. Volume-dependent compliance was analyzed using the SLICE-method. MIP-pressure correlated to the intra-abdominal pressure (r(2)=0.94, p0.001). Peak inspiratory pressure increased with intra-abdominal pressure, and was lower after recruitment-maneuvers (p0.001). The compliance gain following recruitment-maneuvers depended on PEEP, intra-abdominal pressure and intratidal volume (all p0.001). Mean arterial pressure was independent of PEEP (p=0.068) and intra-abdominal pressure (p=0.293). Volume-dependent compliance courses varied according to PEEP and intra-abdominal pressure. The level of intra-abdominal pressure alters respiratory system mechanics in healthy lungs. Intratidal compliance can be used to guide the PEEP adjustment in intra-abdominal hypertension. If counterbalanced by PEEP, elevated intra-abdominal pressure has no negative effects on oxygenation or hemodynamics.

Transfer of too high mechanical energy from the ventilator to the lung's alveolar tissue is the main cause for ventilator-induced lung injury (VILI). To investigate the effects of cyclic energy transfer to the alveoli, we introduce a new method of transthoracic endoscopy that provides morphological as well as functional information about alveolar geometry and mechanics. We evaluate the new endoscopic method to continuously record images of focused subpleural alveoli. The method is evaluated by using finite element modeling techniques and by direct observation of subpleural alveoli both in isolated rat lungs as well as in intact animals (rats). The results confirm the overall low invasiveness of the endoscopic method insofar as the mechanical influences on the recorded alveoli are only marginal. It is, hence, a suited method for intravital microscopy in the rat model as well as in larger animals.

New reconstructive and less invasive methods have been searched to optimize bone formation and osseointegration of dental implants in maxillary sinus augmentation.The aim of the presented ovine split-mouth study was to compare bovine bone mineral (BBM) alone and in combination with mesenchymal stem cells (MSCs) regarding their potential in sinus augmentation.Bilateral sinus floor augmentations were performed in six adult sheep. BBM and MSCs were placed into the test side and only BBM in the contra-lateral control side of each sheep. Animals were sacrificed after 8 and 16 weeks. Augmentation sites were analyzed by computed tomography, histology, and histomorphometry.The initial volumes of both sides were similar and did not change significantly with time. A tight connection between the particles of BBM and the new bone was observed histologically. Bone formation was significantly (p = 0.027) faster by 49% in the test sides.The combination of BBM and MSCs accelerated new bone formation in this model of maxillary sinus augmentation. This could allow early placement of implants.

Background Doxorubicin causes a chronic cardiomyopathy in which genetic and functional lesions of mitochondria accumulate in the long-term. A disrupted Ca 2+ homeostasis is also implicated in doxorubicin cardiotoxicity. We investigated if the alterations in myocellular Ca 2+ are primary or secondary to the respiratory chain dysfunction in chronic doxorubicin cardiomyopathy. Methods and Results A "long-observation group" of rats was treated with intravenous doxorubicin (1 mg/kg per week) for 7 weeks, starting at 11 weeks of age. Controls received equivalents of saline. A "short-observation group" received seven injections of doxorubicin, starting at 41 weeks of age. All rats were euthanized at 48 weeks of age. Only the long-observation rats developed a significant clinical, macroscopic, histological, and ultrastructural cardiomyopathy. Their intramyocardial cytochrome c oxidase (COX) activity was lowest; they had the highest loss of mitochondrial DNA (mtDNA) and its encoded respiratory chain subunit COX I, and the highest amount of ultrastructural and intracellular calcium accumulation resembling hydroxyapatite. The short-term-group hearts had fewer alterations of the cardiomyopathy score, COX-activity, and mtDNA-content than the long-observation group. Despite a measurable loss of mtDNA and its encoded respiratory chain activity, however, there was virtually no detectable calcium accumulation in the hearts of the short-term group. Conclusions mtDNA depletion and secondary respiratory chain dysfunction precedes the precipitation of mitochondrial calcium deposits in chronic doxorubicin cardiotoxicity.

During one-lung ventilation (OLV), hypoxic pulmonary vasoconstriction reduces venous admixture and attenuates the decrease in arterial O2 tension by diverting blood from the nonventilated to the ventilated lung. In vitro, increasing concentrations of desflurane depresses hypoxic pulmonary vasoconstriction in a dose-dependent manner. Accordingly, we investigated the effects of increasing concentrations of desflurane on oxygenation during OLV in vivo. Thirteen pigs (25-30 kg) were anesthetized (induction: propofol 2-3 mg/kg IV; maintenance: N2 O/O2 50%/50%, desflurane 3%, propofol 50 [micro sign]g [middle dot] kg-1 [middle dot] min-1, and vecuronium 0.2 mg [middle dot] kg-1 [middle dot] h-1 IV), orotracheally intubated, and mechanically ventilated. After placement of femoral arterial and thermodilution pulmonary artery catheters, a left-sided, 28F, double-lumen tube was placed via tracheotomy. After double-lumen tube placement, N2 O and desflurane were discontinued, propofol was increased to 200 [micro sign]g [middle dot] kg-1 [middle dot] min-1, and the fraction of inspired oxygen was adjusted at 0.8. Anesthesia was then continued in random order with desflurane 5%, 10%, or 15% end-tidal concentrations while propofol was discontinued. Whereas mixed venous PO2, mean arterial pressure, cardiac output, and shunt fraction decreased in a dose-dependent manner, PaO2 remained unchanged with increasing concentrations of desflurane during OLV. These findings indicate that, in vivo, increasing concentrations of desflurane do not necessarily worsen oxygenation during OLV. Implications: Oxygenation during one-lung ventilation depends on reflex vasoconstriction in the nonventilated lung. In vitro, desflurane inhibits this reflex dose-dependently. Our results indicate that, in vivo, this does not necessarily translate to dose-dependent decreases in oxygenation during one-lung ventilation. (Anesth Analg 1999;89:215-7)

Objective: In a previous experimental study on 60 freshly slaughtered pig trachea, a statistically significant better resistance to pressure was found after mechanical stapling compared to hand suture. The objective of this study was to determine the resistance to pressure of a bronchial stump depending upon the closure technique (manual vs. mechanical) used in sheep 14 days after pneumonectomy. Methods: Pneumonectomy was performed on 30 sheep, which were alternatively closed either by a double-layer running suture at 908 to the cartilaginous rings or with an automatic stapling device. Exactly 14 days after pneumonectomy, the animals were sacrificed and the trachea with the bronchial stump was retrieved. Sutures were placed under pressure until air leakage was observed. The air-leakage pressure was recorded digitally. Results: In both groups, there was no evidence of a bronchopleural fistula. As in the previous experimental study, mean values of air-leakage pressure revealed a large standard deviation in both groups (min. 0.16–max. 1.15 bar). Unlike the results in the first experiment there was no statistically significant difference between the two groups. Conclusions: After 14 days, when a bronchial stump is considered to be healed, the resistance to pressure of a mechanical suture is equal to that of the manual suture. q 2004 Elsevier B.V. All rights reserved.

Background— Doxorubicin causes a chronic cardiomyopathy of unknown pathogenesis. We investigated whether acquired defects in mitochondrial DNA (mtDNA) and interconnected respiratory chain dysfunction may represent a molecular mechanism for its late onset. Methods and Results— Rats were treated weekly with intravenous doxorubicin (1 mg/kg) for 7 weeks, starting at 11 weeks of age (group B). Controls received saline. Group C received doxorubicin identically to group B, but the course was started at 41 weeks of age. All rats were killed at week 48. Doxorubicin was also injected once, either 6 days (group D) or 2 hours (group E) before euthanasia. Heart and skeletal muscle were examined. Only group B rats developed a significant clinical, macroscopic, histological, and ultrastructural cardiomyopathy. Group B hearts had the lowest cytochrome c oxidase (COX) activity (24% of controls; P =0.003), the highest citrate synthase activity (135% of controls; P =0.005), and the highest production of superoxide. In group B, the respiratory subunit COXI, which is encoded by mtDNA, was reduced ( P P P =0.006), higher COX activity ( P =0.02), and higher mtDNA content ( P =0.04). Group B and to a lesser extent group C hearts contained deleted mtDNA. There was no detectable mitochondrial toxicity in group D and E hearts or in skeletal muscle. Conclusions— In doxorubicin cardiomyopathy, mtDNA alterations, superoxide, and respiratory chain dysfunction accumulate long-term in the absence of the drug and are associated with a late onset.