Endoscopic mucosal resection in the esophagus with a new rigide device : an animal study

Résumé: Introduction : L'utilisation de méthodes endoscopiques peu invasives est en constante augmentation pour le traitement des lésions tumorales précoces de l'oesophage. Le but du traitement comprend l'éradication complète de tous les foyers de dysplasie ou de carcinome in situ, notamment dans les métaplasies intestinales de l'oesophage de Barrett, qui peuvent dégénérer en adénocarcinome. Plusieurs techniques d'ablation de la muqueuse oesophagienne (laser, argon plasma, electrocoagulation, photothérapie dynamique, résection endoscopique) ont été utilisées jusqu'à présent, mais aucune n'a vraiment donné entière satisfaction. Les techniques actuelles de résections endoscopiques par fibroscopie sont entre autres limitées par le grand nombre de séances nécessaires à l'éradication complète de la lésion et par la petite taille des fragments de muqueuse obtenus, ce qui rend l'analyse histologique difficile. Dans notre étude animale, nous avons évalué la faisabilité, l'efficacité et la sécurité d'une méthode de résection endoscopique à l'aide d'un nouvel oesophagoscope rigide. Matériel et méthode : Le résectoscope est formé d'un oesophagoscope rigide avec une fenêtre distale transparente à travers laquelle la muqueuse et une partie de la sous-muqueuse sont aspirées et ensuite réséquées avec une anse thermique. Les diverses fenêtres utilisées ont une taille comprise entre 2.2 et 4.4 cm. Le mouton a été choisi en raison de la ressemblance de son oesophage avec celui de l'humain en ce qui concerne l'épaisseur de son oesophage et sa structure histologique. Nous avons effectué 55 résections hémi-circonférentielles sur 21 animaux et 11 résections circonférentielles sur 11 autres. La Mitomycine-C, une substance qui inhibe la prolifération fibroblastique, a été utilisée dans 8 résections circonférentielles à différents intervalles de temps afin d'empêcher la survenue de sténoses oesophagiennes. Résultats : Toutes les résections hémi-circonférentielles ont permis d'obtenir des fragments compacts de tissu avec des bords nets, ce qui permet une excellente étude histologique. La surface du tissu prélevé était en corrélation avec la taille de la fenêtre du resectoscope. Nous avons ainsi pu obtenir des fragments avec des dimensions comprises entre 6 et 12 cm2. Pour les résections circonférentielles, les tissus étaient obtenus en 2 parties, en inversant de 180° la position de l'appareil. La profondeur de la résection a été optimale dans 58 cas sur 65 avec une découpe précise au niveau de la sous-muqueuse sans lésion de la couche musculaire sous- jacente. Il n'y a pas eu de complications après les résections hémi-circonférentielles. Les complications engendrées par les résections circonférentielles (sténose, perforation) n'ont plus été rencontrées après application locale de Mitomycine-C administrée à des intervalles de temps bien précis. Conclusion : Notre méthode de résection endoscopique de la muqueuse oesophagienne offre une nouvelle approche très prometteuse par rapport aux options déjà disponibles. Elle apparaît supérieure en ce qui concerne la taille de tissu prélevé, la précision et régularité de la profondeur de résection, ainsi que la facilité et sûreté du diagnostic histologique et des marges de sécurité. Les résections hémi-circonférentielles se sont révélées sûres chez le modèle animal. Cette nouvelle technique mérite de plus amples investigations pour les résections circonférentielles avant son utilisation chez l'humain. Abstract: Background and Study Aims: We undertook this retrospective study to evaluate the frequency and prognosis of endoscopic treatment of laterally spreading tumors (LSTs) in the rectum. The recurrence rate for lesions of the lower rectum was compared with that of the upper rectum. Patients and Methods: During the period from July 1989 to June 2002, a total of 1237 rectal tumors were detected. LSTs accounted for 6.9% (85/1237) of all rectal tumors. A total of 224 tumors of the lower rectum were detected among the 1237 rectal tumors. LSTs accounted for 16.1 % (36/224) of all the lower rectal tumors. From 85 LST lesions, 67 were evaluated for their prognosis after endoscopic mucosal resection (EMR). Patients whose LSTs had been resected were followed up by endoscopy at the following frequencies: once 15 (22.4%); twice (more than 1 year), 20 (29.9%); three times (more than 3 years), 21(31.3%); and four times or more (more than 5 years), 11 (16.4%). Results: A total of 67 patients with endoscopically treated LSTs were followed up by endoscopy. We observed recurrences in two lesions of the upper rectum (2/38, 5.3%) and five lesions of the lower rectum (5/29, 17.2%) (P = 0.2364); all seven lesions were resected piecemeal. LSTs whose horizontal margin reached the pectinate line frequently recurred in the lower rectum, at a rate of 80% (4/5). However, all patients were completely cured by additional endoscopic resections, the greatest number of treatments being four. Conclusion: For early detection of recurrence and successful endoscopic cure, further colonoscopic examination within a few months after the first treatment is necessary.

Translation of biomechanical concepts in bone tissue engineering: from animal study to revision knee arthroplasty.

Bone defects in revision knee arthroplasty are often located in load-bearing regions. The goal of this study was to determine whether a physiologic load could be used as an in situ osteogenic signal to the scaffolds filling the bone defects. In order to answer this question, we proposed a novel translation procedure having four steps: (1) determining the mechanical stimulus using finite element method, (2) designing an animal study to measure bone formation spatially and temporally using micro-CT imaging in the scaffold subjected to the estimated mechanical stimulus, (3) identifying bone formation parameters for the loaded and non-loaded cases appearing in a recently developed mathematical model for bone formation in the scaffold and (4) estimating the stiffness and the bone formation in the bone-scaffold construct. With this procedure, we estimated that after 3 years mechanical stimulation increases the bone volume fraction and the stiffness of scaffold by 1.5- and 2.7-fold, respectively, compared to a non-loaded situation.

Extensive circumferential endoscopic mucosal resection with a new rigid esophagoscope: an animal study

RÉSUME Les techniques de résection muqueuse endoscopique utilisées actuellement ne permettent pas d'effectuer une résection circonférentielle d'un long segment de muqueuse oesophagienne. Une telle résection permettrait le traitement de foyers multicentriques de dysplasies de haut grade (HGIN) ou d'adénocarcinomes précoces (AC) développés sur oesophage de Barrett. Sachant que la prévalence des métastases ganglionnaires régionales est d'environ 7 % pour les adénocarcinomes intra-muqueux (Tis,T1a), les méthodes de traitement non-chirurgicales et moins invasives sont actuellement préférées à une oesophagectomie, dont la morbidité et la mortalité restent élevées en comparaison avec les mucosectomies endoscopiques. Un oesophagoscope rigide modifié a été développé à Lausanne en collaboration avec la maison Karl Storz GmbH, de façon à permettre des résections muqueuses étendues dans l'oesophage. Cette étude animale pilote a investigué la faisabilité et la fiabilité des résections muqueuses circonférentielles de différentes longueurs dans l'oesophage du mouton. Des résections circonférentielles de 2,2 cm (n=6), 3,3 cm (n=6), 4,4 cm (n=7) et 5,5 cm (n=5) de longueur ont été effectuées dans l'oesophage de 24 moutons. Elles consistaient en 2 mucosectomies hémi-circonférentielles opposées. Les animaux ont été suivis par des examens endoscopiques à une semaine puis chaque mois pendant 6 mois ou jusqu'à réépithélialisation complète sans sténose. Au cours du processus de guérison, les sténoses cicatricielles ont été traitées par une ou plusieurs dilatations avec les bougies de Savary. Des résections circonférentielles de 2,2 à 5,5 cm de longueur ont été réalisées avec succès dans 23/24 des cas. Une seule perforation, secondaire à une erreur de manipulation, est survenue directement après la mucosectomie. A l'analyse histologique, une profondeur de résection précise à travers la sousmuq Tyrp1ueuse a été obtenue dans 85% des specimens. Les sténoses cicatricielles ont été contrôlées dans 95% des cas par dilatations avec les bougies de Savary. L'oesophagoscope rigide modifié a permis de réaliser des résections muqueuses circonférentielles et étendues en une seule séance endoscopique d'une durée de moins d'une demi-heure. L'utilisation de ce résectoscope chez l'homme devrait permettre l'éradication complète de l'oesophage de Barrett avec HGIN et/ou AC précoce dans un avenir très proche.

Experimental evaluation of an electromechanical artificial urinary sphincter in an animal model.

WHAT'S KNOWN ON THE SUBJECT? AND WHAT DOES THE STUDY ADD?: The AMS 800 urinary control system is the gold standard for the treatment of urinary incontinence due to sphincter insufficiency. Despite excellent functional outcome and latest technological improvements, the revision rate remains significant. To overcome the shortcomings of the current device, we developed a modern electromechanical artificial urinary sphincter. The results demonstrated that this new sphincter is effective and well tolerated up to 3 months. This preliminary study represents a first step in the clinical application of novel technologies and an alternative compression mechanism to the urethra. OBJECTIVES: To evaluate the effectiveness in continence achievement of a new electromechanical artificial urinary sphincter (emAUS) in an animal model. To assess urethral response and animal general response to short-term and mid-term activation of the emAUS. MATERIALS AND METHODS: The principle of the emAUS is electromechanical induction of alternating compression of successive segments of the urethra by a series of cuffs activated by artificial muscles. Between February 2009 and May 2010 the emAUS was implanted in 17 sheep divided into three groups. The first phase aimed to measure bladder leak point pressure during the activation of the device. The second and third phases aimed to assess tissue response to the presence of the device after 2-9 weeks and after 3 months respectively. Histopathological and immunohistochemistry evaluation of the urethra was performed. RESULTS: Bladder leak point pressure was measured at levels between 1091 ± 30.6 cmH2 O and 1244.1 ± 99 cmH2 O (mean ± standard deviation) depending on the number of cuffs used. At gross examination, the explanted urethra showed no sign of infection, atrophy or stricture. On microscopic examination no significant difference in structure was found between urethral structure surrounded by a cuff and control urethra. In the peripheral tissues, the implanted material elicited a chronic foreign body reaction. Apart from one case, specimens did not show significant presence of lymphocytes, polymorphonuclear leucocytes, necrosis or cell degeneration. Immunohistochemistry confirmed the absence of macrophages in the samples. CONCLUSIONS: This animal study shows that the emAUS can provide continence. This new electronic controlled sequential alternating compression mechanism can avoid damage to urethral vascularity, at least up to 3 months after implantation. After this positive proof of concept, long-term studies are needed before clinical application could be considered.

Active mitral ring for post-surgical remote correction of residual mitral regurgitation on the beating heart.

OBJECTIVES: Residual mitral regurgitation after valve repair worsens patients' clinical outcome. Postimplant adjustable mitral rings potentially address this issue, allowing the reshaping of the annulus on the beating heart under echocardiography control. We developed an original mitral ring allowing valve geometry remodelling after the implantation and designed an animal study to assess device effectiveness in correcting residual mitral regurgitation. METHODS: The device consists of two concentric rings: one internal and flexible, sutured to the mitral annulus and a second external and rigid. A third conic element slides between the two rings, modifying the shape of the flexible ring. This sliding element is remotely activated with a rotating tool. Animal model: in adult swine, under cardio pulmonary bypass and cardiac arrest, we shortened the primary chordae of P2 segment to reproduce Type III regurgitation and implanted the active ring. We used intracardiac ultrasound to assess mitral regurgitation and the efficacy of the active ring to correct it. RESULTS: Severe mitral regurgitation (3+ and 4+) was induced in eight animals, 54 ± 6 kg in weight. Vena contracta width decreased from 0.8 ± 0.2 to 0.1 cm; proximal isovelocity surface area radius decreased from 0.8 ± 0.2 to 0.1 cm and effective regurgitant orifice area decreased from 0.50 ± 0.1 to 0.1 ± 0.1 cm(2). Six animals had a reversal of systolic pulmonary flow that normalized following the activation of the device. All corrections were reversible. CONCLUSIONS: Postimplant adjustable mitral ring corrects severe mitral regurgitation through the reversible modification of the annulus geometry on the beating heart. It addresses the frequent and morbid issue of recurrent mitral valve regurgitation.

Is the GraftConnector a valid alternative to running suture in end-to-side coronary arteries anastomoses?

BACKGROUND: An animal study was carried out to compare long-term patency rates of coronary anastomoses performed with the GraftConnector versus running suture technique. METHODS: 10 sheep, 45 to 55 kg, underwent off-pump coronary artery bypass grafting (right internal mammary artery to left anterior descending artery). In 5 animals, the anastomosis was performed with a GraftConnector and in 5 animals with 7-0 running suture. Intraoperative fluoroscopy and a fluoroscopic control at 6 months were performed. After 6 months, the animals were sacrificed and the anastomoses were examined histologically. RESULTS: All animals survived at 6 months with 100% anastomosis patency rates in both groups. In the GraftConnector group, the anastomosis diameter at 6 months fluoroscopy was 118% of native left anterior descending artery versus 97% of the control group. Luminal anastomotic width at histology was 1.7 +/- 0.2 mm in the device group versus 1.6 +/- 0.1 mm in the control group. Mean intimal hyperplasia thickness was 0.21 +/- 0.1 mm in the device group versus 0.01 mm in the control group. CONCLUSIONS: The GraftConnector provides a consistent and reproducible coronary artery anastomosis and reduces technical demand and manual dexterity in coronary operations. Long-term results demonstrate that off-pump coronary artery bypass grafting performed with the GraftConnector had the same patency rate and luminal width as those performed with running suture.

Artificial muscle to wash blood out of fibrillating atrium: an alternative to lifelong anticoagulation.

The Atripump is a motorless, volume displacement pump based on artificial muscle technology that could reproduce the pump function of normal atrium. It could help prevent blood clots due to blood stagnation and eventually avoid anticoagulation therapy in atrial fibrillation (AF). An animal study has been designed to assess mechanical effects of this pump on fibrillating atrium. The Atripump is a dome shaped silicone coated nitinol actuator. A pacemaker like control unit drives the actuator. In five adult sheep, the right atrium (RA) was exposed and dome sutured onto the epicardium. Atrial fibrillation was induced using rapid epicardial pacing (600 beats/min). Ejection fraction of the RA was obtained with intracardiac ultrasound in baseline, AF and Atripump assisted AF conditions. The dome's contraction rate was 60/min with power supply of 12V, 400 mA for 200 ms and ran for 2 hours in total. Mean temperature on the RA was 39+/-1.5 degrees C. Right atrium ejection fraction was 31% in baseline conditions, 5% and 20% in AF and assisted AF, respectively. In two animals a thrombus appeared in the right appendix and washed out once the pump was turned on. The Atripump washes blood out the RA acting as an anticoagulant device. Possible clinical implications in patients with chronic AF are prevention of embolism of cardiac origin and avoidance of hemorrhagic complication due to chronic anticoagulation.

Endoscopic off-pump aortic valve replacement: does the pericardial cuff improve the sutureless closure of left ventricular access?

OBJECTIVE: Off-pump trans left ventricular approach provides more precise deployment of stented aortic valve of any size with respect to the endovascular replacement. One of the key steps of this procedure is the ventricle repair after catheter withdrawing. We designed an animal study to compare the consistency of a sutureless repair of the left ventricle access using nitinol occluder with and without pericardial cuff on the ventricular side. METHODS: Material description: The Amplatz-nitinol occluder consists of two square heads squeezing ventricle wall in between them, sealing the defect. To improve its sealing property, a pericardial patch was sutured to the ventricular head of the occluder. Animal study setup: In adult pigs, a 30F sheath was inserted into the epigastric area through the cardiac apex, up to the left ventricle, simulating the approach for off-pump aortic valve replacement. The sheath was then removed and the ventricle closed with standard occluder in half of the animals, and cuffed occluder in the other half. Animals were followed-up for 3h, collecting haemodynamics data and pericardial bleeding. RESULTS: Device was successfully deployed in 12 animals in less than 1min. In the group where the standard occluder was used, bleeding during the deployment was 80+/-20ml and after the deployment was 800+/-20ml over 3h. In the group where the cuffed occluder was used, bleeding during the deployment was 85+/-20ml and after the deployment was 100+/-5ml over 3h. In the cuffed group, bleeding was significantly lower than the standard group, p-value being <0.001. CONCLUSIONS: The occluder is easy to use and the pericardial cuff dramatically increases its efficacy as demonstrated by a significant reduction of blood loss. The cuffed occluder opens the way for endoscopic, off-pump, transventricular aortic valve replacement.

Towards no-scar cardiac surgery - minimally invasive access through umbilicus for aortic valve replacement.

There is an ever-growing trend towards less-invasive procedures in all fields of medicine. We designed an animal study to prove the concept that trans-apical aortic valve replacement from an incision within the umbilicus through a single channel for instruments is feasible, which would be a major leap towards no-scar cardiac surgery. In three adult pigs, after creating a single 3-cm incision at a place where the human umbilicus would be, we introduced a 30F sheath through a tunnel created by an endoscopic vein-harvesting device up to the cardiac apex, through it and up to the left ventricle simulating the approach for trans-apical aortic valve replacement. We used a standard Amplatz nitinol occluder to seal the defect in ventricle wall later. The animals were followed up for 1h. Blood loss was minimal, and no tamponade occurred in any of the animals. In addition, we performed a test with water column static pressure to evaluate the impact of preclotting on the sealing properties of the occluders: 1 min flow-through was 2860+/-176 ml for the standard occluders and 348+/-56 ml for preclotted occluders (p<0.001).

Progress in cardiovascular anastomoses: will the vascular join replace Carrel's technique?

BACKGROUND: Vascular reconstructions are becoming challenging due to the comorbidity of the aging population and since the introduction of minimally invasive approaches. Many sutureless anastomosis devices have been designed to facilitate the cardiovascular surgeon's work and the vascular join (VJ) is one of these. We designed an animal study to assess its reliability and long-term efficacy. METHODS: VJ allows the construction of end-to-end and end-to-side anastomoses. It consists of two metallic crowns fixed to the extremity of the two conduits so that vessel edges are joined layer by layer. There is no foreign material exposed to blood. In adult sheep both carotid arteries were prepared and severed. End-to-end anastomoses were performed using the VJ device on one side and the classical running suture technique on the other side. Animals were followed-up with Duplex-scan every 3 months and sacrificed after 12 months. Histopathological analysis was carried out. RESULTS: In 20 animals all 22 sutureless anastomoses were successfully completed in less than 2 min versus 6 +/- 3 min for running suture. Duplex showed the occlusion of three controls and one sutureless anastomosis. Two controls and one sutureless had stenosis >50%. Histology showed very thin layer of myointimal hyperplasia (50 +/- 10 microm) in the sutureless group versus 300 +/- 27 microm in the control. No significant inflammatory reaction was detected. CONCLUSIONS: VJ provides edge-to-edge vascular repair that can be considered the most physiological way to restore vessel continuity. For the first time, in healthy sheep, an anastomotic device provided better results than suture technique.

Fluorine-19 magnetic resonance angiography of the mouse.

PURPOSE: To implement and characterize a fluorine-19 ((19)F) magnetic resonance imaging (MRI) technique and to test the hypothesis that the (19)F MRI signal in steady state after intravenous injection of a perfluoro-15-crown-5 ether (PCE) emulsion may be exploited for angiography in a pre-clinical in vivo animal study. MATERIALS AND METHODS: In vitro at 9.4T, the detection limit of the PCE emulsion at a scan time of 10 min/slice was determined, after which the T(1) and T(2) of PCE in venous blood were measured. Permission from the local animal use committee was obtained for all animal experiments. 12 µl/g of PCE emulsion was intravenously injected in 11 mice. Gradient echo (1)H and (19)F images were obtained at identical anatomical levels. Signal-to-noise (SNR) and contrast-to-noise (CNR) ratios were determined for 33 vessels in both the (19)F and (1)H images, which was followed by vessel tracking to determine the vessel conspicuity for both modalities. RESULTS: In vitro, the detection limit was ∼400 µM, while the (19)F T(1) and T(2) were 1350±40 and 25±2 ms. The (19)F MR angiograms selectively visualized the vasculature (and the liver parenchyma over time) while precisely coregistering with the (1)H images. Due to the lower SNR of (19)F compared to (1)H (17±8 vs. 83±49, p<0.001), the (19)F CNR was also lower at 15±8 vs. 52±35 (p<0.001). Vessel tracking demonstrated a significantly higher vessel sharpness in the (19)F images (66±11 vs. 56±12, p = 0.002). CONCLUSION: (19)F magnetic resonance angiography of intravenously administered perfluorocarbon emulsions is feasible for a selective and exclusive visualization of the vasculature in vivo.

Atrial assist device, a new alternative to lifelong anticoagulation?

OBJECTIVE: Atrial fibrillation is a very common heart arrhythmia, associated with a five-fold increase in the risk of embolic strokes. Treatment strategies encompass palliative drugs or surgical procedures all of which can restore sinus rhythm. Unfortunately, atria often fail to recover their mechanical function and patients therefore require lifelong anticoagulation therapy. A motorless volume displacing device (Atripump) based on artificial muscle technology, positioned on the external surface of atrium could avoid the need of oral anticoagulation and its haemorrhagic complications. An animal study was conducted in order to assess the haemodynamic effects that such a pump could provide. METHODS: Atripump is a dome-shape siliconecoated nitinol actuator sewn on the external surface of the atrium. It is driven by a pacemaker-like control unit. Five non-anticoagulated sheep were selected for this experiment. The right atrium was surgically exposed, the device sutured and connected. Haemodynamic parameters and intracardiac ultrasound (ICUS) data were recorded in each animal and under three conditions; baseline; atrial fibrillation (AF); atripump assisted AF (aaAF). RESULTS: In two animals, after 20 min of AF, small thrombi appeared in the right atrial appendix and were washed out once the pump was turned on. Assistance also enhanced atrial ejection fraction. 31% baseline; 5% during AF; 20% under aaAF. Right atrial systolic surfaces (cm2) were; 5.2 +/- 0.3 baseline; 6.2 +/- 0.1 AF; 5.4 +/- 0.3 aaAF. CONCLUSION: This compact and reliable pump seems to restore the atrial "kick" and prevents embolic events. It could avoid long-term anticoagulation therapy and open new hopes in the care of end-stage heart failure.

Apical closure device for transapical valve procedures?.

OBJECTIVES: Transapical transcatheter valve procedures are performed through a left minithoracotomy and require apical sutures to seal the apical access site. The use of large-calibre devices compromises any attempt to fully perform the procedure with a thoracoscopic approach or percutaneously. We report our preliminary experience in animals with a new sutureless self-expandable apical occluder, engineered to perform transapical access site closure in a minimally invasive setting with large-size introducer sheaths. METHODS: The apical occluder with extendable waist was implanted in six young pigs during an acute animal study. Under general anaesthesia, animals (mean weight: 62 ± 8 kg) received full heparinization (heparin: 100 UI/kg; activated clotting time above 250 s). Through a median sternotomy, a 21-Fr Certitude? introducer sheath (outer diameter: 25 Fr) was placed over the wire into the cardiac apex. The delivery catheter carrying the constrained apical plug was inserted into the sheath and deployed under fluoroscopic control, whereas the Certitude? was retrieved. After protamine infusion, we observed and recorded the 1-h bleeding with standard haemodynamic parameters. Animals were sacrificed, and hearts analysed. RESULTS: Six apical closure devices were successfully introduced and deployed in six pig hearts through large-size apical sheaths at first attempt. In all animals, the plugs guaranteed immediate apical sealing and traces of blood were collected in the pericardium during the 1-h observational period (mean of 16 ± 3.4 ml of blood loss per animal). Haemodynamic parameters remained stable during the entire study period and no plug dislodgement was detected with normal systemic blood pressure (mean arterial mean blood pressure: 65 ± 7 mmHg). Post-mortem analysis confirmed the full deployment and good fixation of all plugs, without macroscopic damages to the surrounding myocardium. CONCLUSIONS: This sutureless self-expandable apical occluder is a simple device capable of sealing large-size apical access sites (20-35 Fr) in an acute animal study. This approach is a step further towards less invasive transapical valve procedures in the clinical setting, and further animal tests will be performed to confirm the long-term efficacy and safety of this device.

Avian erythrocytes have functional mitochondria, opening novel perspectives for birds as animal models in the study of ageing.

BACKGROUND: In contrast to mammalian erythrocytes, which have lost their nucleus and mitochondria during maturation, the erythrocytes of almost all other vertebrate species are nucleated throughout their lifespan. Little research has been done however to test for the presence and functionality of mitochondria in these cells, especially for birds. Here, we investigated those two points in erythrocytes of one common avian model: the zebra finch (Taeniopygia guttata). RESULTS: Transmission electron microscopy showed the presence of mitochondria in erythrocytes of this small passerine bird, especially after removal of haemoglobin interferences. High-resolution respirometry revealed increased or decreased rates of oxygen consumption by erythrocytes in response to the addition of respiratory chain substrates or inhibitors, respectively. Fluorometric assays confirmed the production of mitochondrial superoxide by avian erythrocytes. Interestingly, measurements of plasmatic oxidative markers indicated lower oxidative stress in blood of the zebra finch compared to a size-matched mammalian model, the mouse. CONCLUSIONS: Altogether, those findings demonstrate that avian erythrocytes possess functional mitochondria in terms of respiratory activities and reactive oxygen species (ROS) production. Interestingly, since blood oxidative stress was lower for our avian model compared to a size-matched mammalian, our results also challenge the idea that mitochondrial ROS production could have been one actor leading to this loss during the course of evolution. Opportunities to assess mitochondrial functioning in avian erythrocytes open new perspectives in the use of birds as models for longitudinal studies of ageing via lifelong blood sampling of the same subjects.