Endovascular model of ischemic stroke in swine guided by real-time MRI.

Modeling stroke in animals is essential for testing efficacy of new treatments; however, previous neuroprotective therapies, based on systemic delivery in rodents failed, exposing the need for model with improved clinical relevance. The purpose of this study was to develop endovascular approach for inducing ischemia in swine. To achieve that goal, we used intra-arterial administration of thrombin mixed with gadolinium and visualized the occlusion with real-time MRI. Placement of the microcatheter proximally to rete allowed trans-catheter perfusion of the ipsilateral hemisphere as visualized by contrast-enhanced perfusion MR scans. Dynamic T2*w MRI facilitated visualization of thrombin + Gd solution transiting through cerebral vasculature and persistent hyperintensities indicated occlusion. Area of trans-catheter perfusion dynamically quantified on representative slice before and after thrombin administration (22.20 ± 6.31 cm2 vs. 13.28 ± 4.71 cm2 respectively) indicated significantly reduced perfusion. ADC mapping showed evidence of ischemia as early as 27 min and follow-up T2w scans confirmed ischemic lesion (3.14 ± 1.41 cm2). Animals developed contralateral neurological deficits but were ambulatory. Our study has overcome long lasting challenge of inducing endovascular stroke model in pig. We were able to induce stroke using minimally invasive endovascular approach and observe in real-time formation of the thrombus, blockage of cerebral perfusion and eventually stroke lesion.

Pathological findings in low-field magnetic resonance imaging of the canine spine - a study of 112 patients.

Magnetic resonance imaging (MRI) is a method of choice in diagnosing nervous system disorders. This paper presents the results of a study where selected segments of the canine spine were examined by low-field MRI in 112 patients. Images of pathological changes were obtained in spin echo (SE), fast spin echo (FSE) and hybrid contrast enhancement (3D HYCE) sequences. The cervical region of the spinal cord (C1-C5) was examined in 32 patients, the cervicothoracic region (C6-Th2)- in 14 patients, the thoracolumbar region (Th3-L3) - in 23 patients, and the lumbosacral region (L4-S3) - in 43 patients. The results were used to determine the incidence of pathological changes in different sections of the canine spine, such as intervertebral disc disease (IDD), disc desiccation, syringomyelia and changes characterized by higher uptake of the contrast medium. Intervertebral disc disease was diagnosed in 52.7% of patients and it was the most common abnormality. Disc dehydratation without protrusion or extrusion was noted in 23.2% of animals. Pathological changes with increased uptake of the contrast medium and indicative of neoplastic growth were observed in 13.4% of patients and syringomyelia was diagnosed in 9.82% of the examined animals. The proposed sequences revealed the presence of above abnormalities.

Thromboelastographic profile of goat blood after the experimental injury of the femoral artery and use of QuikClot gauze and Celox gauze dressings.

The aim of this study was to evaluate the suitability of thromboelastometry for the analysis of blood test results in goats after the use of hemostatic dressings to control massive bleeding. The study was carried out on 12 goats, 6 animals in each of two subgroups. In all experimental animals incision of the femoral artery was performed, and bleeding was controlled with QuikClot gauze in the first group and Celox gauze in the second group. Dressings were applied for 60 minutes. Blood samples for thromboelastometry were collected from the jugular vein before the incision and 60 min after the application of a dressing. Clotting time (CT), clot formation time (CFT), maximum clot firmness (MCF) and α angle (°) were measured in three standard ROTEM assays (system with generation of reaction curve, numerical parameters and size of the blood clot): intrinsic coagulation pathway (INTEM), extrinsic coagulation pathway (EXTEM) and functional fibrinogen (FIBTEM). Complete hemostasis of the injured femoral artery was found in all goats. No significant differences between pre- and post-incision thromboelastometric parameters were found in any tests in any of the groups, which indicates that the use of dressings was not associated with blood coagulation disorders. This study is the first to describe the use of thromboelastometry in goats for the assessment of clot formation and hemostatic disorders.

Comparison of Feline Brain Anatomy in 0.25 and 3 Tesla Magnetic Resonance Images.

The intention of the comparison of both low and high field was to examine which anatomical brain structures of cats were visible on low field images, as in clinical veterinary practice, 3 Tesla (T) magnets were of limited availability. The research was performed on 20 European short-haired male and female cats, aged 1-3 years, with body weight of 2-4 kg. 0.25 T magnetic resonance images of neurocranium were acquired in all using T2-weighted fast spin echo sequences with repetition time (TR) of 4010 ms and echo time (TE) of 90 ms in dorsal and transverse plane, and T2-weighted fast spine echo sequences with TR of 4290 ms and TE of 120 ms in sagittal plane. Based on a detailed catalogue of feline brain structures visible at 3 T in previously published studies, it was examined which structures were visible on low field images. Anatomic structures were identified and compared to assess the reliability of diagnoses made based on low-field magnetic resonance imaging. In low-field scans, 92 structures were identified. Elements of auditory, visual, motor pathways, hippocampus and cerebral ventricular system were distinguished. Low-field as well as high-field magnetic resonance imaging support the identification of local tissue lesions, metastasis, focal ischaemia and haemorrhage, disorders associated with ventricular system dilation and hydrocephalus. It also produced accurate images of the hippocampus, which contributes to reliable diagnoses of various forms of epilepsy in cats. Due to technical limitations, a low-field scanner is unlikely to visualize microtraumas, local inflammations, small haematomas or metastatic tumours.

Ultrasonography and Low-field Magnetic Resonance Imaging of the Common Calcanean Tendon in a Rabbit Model for Tendinopathy Research: a Descriptive Study of Normal Anatomy.

In spite of recent advances in treatment protocols, tendinopathies continue to challenge orthopaedists and surgeons. Due to the complexity of both tendon injuries and the healing processes, animal models are essential for addressing fundamental questions in tendinopathy research. Diagnostic imaging could contribute to the evaluation of animal models, thus providing information, which could be translated to human tendinopathies. The objective of our study was to evaluate in situ appearance of the rabbit common calcanean tendon with ultrasonography and magnetic resonance imaging. Additionally, we sought to assess and compare the feasibility and usefulness of these techniques in a rabbit model while focusing on the imaging of the particular structures involved in calcaneal tendon disorders. Eight California rabbits were used for post-mortem sonographic and low-field magnetic resonance examination. Morphometry was performed on longitudinal sonograms and sagittal MRI scans. The craniocaudal diameter of the tendon was measured at four points of interest. Ultrasonography and magnetic resonance provided good visualisation of the tendon origin, the paratenon and the pre-Achilles fat pad. Magnetic resonance images presented in more detail the structure of the calcaneal insertion. Both modalities failed to visualise the individual components of the common calcanean tendon and the bursa of the calcaneal tendon. Statistical analysis of measurements obtained showed that the craniocaudal diameter of the common calcanean tendon in a rabbit increases significantly with a growing length from the calcaneal tuber. Both magnetic resonance and ultrasonography are feasible, and should be considered complementary, not alternative imaging techniques in a rabbit common calcanean tendon model.

The Effectiveness of Modified Seton and Modified Combat Gauze in Controlling Severe Hemorrhaging during Operations of Uniformed Services.

Hemorrhaging from large vessels poses a serious problem in emergency situations when blood loss needs to be immediately controlled. The aim of the study was to compare the effectiveness of two hemostatic dressings in controlling bleeding from a surgically punctured femoral artery. The study was performed on thirteen pigs divided into two groups, of six and seven pigs, respectively. Combat gauze covered with ChitoClear hqg 95 chitosan and Protanal LF10/60 FT sodium alginate was used in the first group, seton covered with identical substances was uses in the second group. Selected hemostatic dressing was applied to the wound 20 seconds after incision and then removed at regular time intervals to evaluate hemostasis. Modified seton was characterized by a shorter time to hemostasis than combat gauze. The result of this experiment indicate that modified seton proved to be a more effective dressing than modified combat gauze.

Comparison of High-field and Low-field Magnetic Resonance Imaging of Stifle Joint Disorders in Dogs.

The most common cause of hindlimb lameness in dogs is cranial cruciate ligament rupture. In 48-77.3% of the population this trauma leads to secondary damage of the meniscus. Depending on the magnetic strength of the used device, different diagnostic accuracy can be achieved. The examination sensitivity of magnetic resonance imaging is affected by many factors which are independent of diagnostic strength, such as correct positioning of the patient, size of the stifle joint examined, or selection of the right protocol of sequences. Sensitivity of meniscus damage detection was 100% and 90%, respectively, in high- and low-field magnetic resonance. The best results were reported during examination of the stifle in dogs above 10 kg b.w. at a flexion angle of 145°, and in sagittal and dorsal planes. Regardless of the magnetic strength applied, imaging of the whole cranial cruciate ligament is difficult. Moreover, MRI allows the detection of the first signs of osteoarthritis, which were observed 4 and 6 weeks after rupture of the cranial cruciate ligament using high and low-field MRI. This also applies to lesions in the subchondral bone or a bone marrow which occurred in association with insufficiency of the stifle joint, and were mainly localized in the epiphysis of the femur and tibia. The present article provides a comparison of different examination protocols and images of damaged stifle structures, such as menisci, ligaments and bones of the stifle joint visualized with low-field and high-field magnetic resonance. Magnetic resonance arthrography is also discussed.

Safety of the long-term application of QuikClot Combat Gauze, ChitoGauze PRO and Celox Gauze in a femoral artery injury model in swine - a preliminary study.

The purpose of this study was to examine the safety of the long-term application of QuikClot Combat Gauze, ChitoGauze PRO and Celox Gauze using a swine model. The study was conducted on nine pigs weighing approximately 30 kg, which were randomly divided into three groups. Under deep anesthesia, the pigs underwent complete transverse cutting of the femoral artery in the groin region. Hemostatic dressings were left in the wound for 24 hours. The animals were euthanized 24 hours after dressing application. In each group, macroscopic and microscopic severe changes and shock symptoms were observed in the lungs, liver, kidneys and heart. Fibrino-gaseous embolic material was found in the pulmonary artery of each group and in the lung vessels of the animals from the ChitoGauze PRO and Celox Gauze groups. In conclusion, the long-term application of the evaluated hemostatic dressings has the risk of coagulopathy and reaching the progressive stage of shock. The residues from the hemostatic dressings can ingress into the systemic circulation, thereby increasing the risk of embolus formation. Because of these harmful effects, the evaluated hemostatic dressings are not appropriate for long-term use. Future studies are needed on the consequences of the long-term application of these hemostatic agents.

The New 3D Printed Left Atrial Appendage Closure with a Novel Holdfast Device: A Pre-Clinical Feasibility Animal Study.

INTRODUCTION: Many patients undergoing cardiac surgery have risk factors for both atrial fibrillation (AF) and stroke. The left atrial appendage (LAA) is the primary site for thrombi formation. The most severe complication of emboli derived from LAA is stroke, which is associated with a 12-month mortality rate of 38% and a 12-month recurrence rate of 17%. The most common form of treatment for atrial fibrillation and stroke prevention is the pharmacological therapy with anticoagulants. Nonetheless this form of therapy is associated with high risk of major bleeding. Therefore LAA occlusion devices should be tested for their ability to reduce future cerebral ischemic events in patients with high-risk of haemorrhage. AIM: The aim of this study was to evaluate the safety and feasibility of a novel left atrial appendage exclusion device with a minimally invasive introducer in a swine model. MATERIALS AND METHODS: A completely novel LAA device, which is composed of two tubes connected together using a specially created bail, was designed using finite element modelling (FEM) to obtain an optimal support force of 36 N at the closure line. The monolithic form of the occluder was obtained by using additive manufacturing of granular PA2200 powder with the technology of selective laser sintering (SLS). Fifteen swine were included in the feasibility tests, with 10 animals undergoing fourteen days of follow-up and 5 animals undergoing long-term observation of 3 months. For one animal, the follow-up was further prolonged to 6 months. The device was placed via minithoracotomy. After the observation period, all of the animals were euthanized, and their hearts were tested for LAA closure and local inflammatory and tissue response. RESULTS: After the defined observation period, all fifteen hearts were explanted. In all cases the full closure of the LAA was achieved. The macroscopic and microscopic evaluation of the explanted hearts showed that all devices were securely integrated in the surrounding tissues. No pericarditis or macroscopic signs of inflammation at the site of the device were found. All pigs were in good condition with normal weight gain and no other clinical symptoms. CONCLUSION: This novel 3D printed left atrial appendage closure technique with a novel holdfast device was proven to be safe and feasible in all pigs. A benign healing process without inflammation and damage to the surrounding structures or evidence of new thrombi formation was observed. Moreover, the uncomplicated survival and full LAA exclusion in all animals demonstrate the efficacy of this novel and relatively cheap device. Further clinical evaluation and implementation studies should be performed to introduce this new technology into clinical practice.

Laparoscopic pyloromyotomy and pyloroplasty in dogs.

This article describes clinical experiments involving laparoscopic pyloromyotomy and pyloroplasty in six dogs diagnosed with hypertrophy of the pyloric sphincter. Laparoscopic pyloromyotomy was performed in three dogs, and pyloroplasty was carried out in the remaining three animals. The patients were operated on based on the authors' previous experiences with experimental pyloromyotomy and pyloroplasty in pigs. Pyloromyotomy and pyloroplasty resulted in full recovery and complete subsidence of symptoms in all patients.

Experimental laparoscopic pyloromyotomy in pigs.

The objective of this study was to evaluate and compare laparoscopic pyloromyotomy methods involving the laparoscopic scalpel and the harmonic scalpel in pigs. The experiment was conducted on 4 subgroups of 12 animals subjected to laparoscopic-assisted pyloromyotomy with a surgical scalpel and the harmonic scalpel, as well as laparoscopic pyloromyotomy with Berci's laparoscopic scalpel and the harmonic scalpel. No postsurgical complications were observed. Four weeks after the surgery, the animals were sacrificed and autopsy was performed. In one animal peritoneal adhesions between the intestines and the mini-laparotomy incision were found. Laparoscopic pyloromyotomy and laparoscopic-assisted pyloromyotomy performed in pigs enabled the selection of laparoscopic entry sites, instruments for pyloromyotomy and evaluation of the applied surgical procedures in animals. The results of this study indicate that the methods applied can be safely used in clinical practice in dogs and cats due to minimal post-operative complications and fast healing of laparoscopic incisions in comparison with classical surgical wounds, and that the harmonic scalpel is a safe surgical instru- ment.

Effect of 24 hour application of three hemostatic dressings to porcine thigh muscles.

The effectiveness of three types of hemostatic dressings, QuikClot Gauze, ChitoGauze PRO and Celox Gauze, was evaluated in nine pigs. The results indicated a strong influence of all examined dressings on porcine femoral muscle tissue evaluated 24 hours after direct contact. A histopathological analysis revealed pathological changes in muscle tissue specimens collected from all the animals.

The use of magnetic resonance imaging in diagnosing equine deep digital flexor tendinopathies--own experience.

Deep digital flexor tendinopathy is a common problem in horses of different athletic disciplines. Nowadays, the use of magnetic resonance imaging is considered to be a noninvasive and superior choice for recognizing bone and soft tissue pathologies especially related to difficult to access structures within the hoof capsule.

Comparison of high resolution gradient echo, XBONE T1, XBONE T2, Spin Echo T1 and 3D SST1 magnetic resonance imaging sequences for imagining the canine elbow.

Twenty canine elbows were examined by low-field MRI. The objective of this study was to compare five magnetic resonance sequences: High Resolution Gradient Echo in the sagittal plane, XBONE T2 in the sagittal plane, Spin Echo T1 in the sagittal plane, Spin Echo T1 in the dorsal plane and 3D SST1 and XBONE T1 in the transverse plane, and to determine which sequences have the highest diagnostic value in imagining the canine elbow. High Resolution Gradient Echo, XBONE T2 and Spin Echo T1 sequences in the sagittal plane proved to be very useful in evaluations of osseous structures such as the medial coronoid process, the anconeal process of the ulna and joint surfaces. The above sequences facilitate evaluations of radial extensor muscle of the wrist, biceps brachii muscle, triceps brachii muscle and the flexor carpi ulnaris muscle. 3D SST1 and XBONE T1 sequences in the transverse plane produce high-quality images of the medial humeral condyle and surfaces of the elbow joint. Those sequences are also useful for evaluating the surrounding muscles: extensor digitorum communis muscle, extensor carpi radialis muscle, deltoid muscle, biceps brachii muscle, pronator teres muscle and flexor carpi ulnaris muscle. The Spin Echo T1 sequence in the dorsal plane facilitates assessments of joint surfaces, medial humeral condyle, superficial digital flexor muscle, deep digital flexor muscle, triceps brachii muscle and extensor digitorum lateralis muscle. The Spin Echo T1 sequence in the sagittal plane has a short scan time, but it produces images of lower quality than High Resolution Gradient Echo and XBONE T2 sequences in the sagittal plane.

Electroencephalography recording analysis in monitoring of canine idiopathic epilepsy treated with phenobarbital. Pilot study.

EEG recording is used in veterinary medicine as a diagnostic tool to support clinical diagnosis of idiopathic epilepsy and to identify focal seizure activity. This retrospective study was designed to compare EEG procedures in 23 dogs with idiopathic epilepsy before and after phenobarbital treatment. Differences among standard deviations for particular bands were significant. During phenobarbital treatment the delta band decreased.

Response of the coagulation system after application of hemostatic dressings in an animal model.

The objective of this study was to determine the response of hemostatic dressings. Coagulation and fibrinolytic systems, red blood cell parameters, platelet and leukocyte counts were evaluated after the application of hemostatic dressings: QuikClot, Chitoauze and Celox gauze. The experiment was performed on ten pigs.

Magnetic resonance imaging assisted with fine needle aspiration biopsy in the diagnosis of fibrosarcomas of the skull in dogs.

Five canine patients were directed to low-field magnetic resonance imaging due to different neurological defects. In each case there were heterogeneous extraaxial masses covering left or right dorsal parietal and occipital lobes that were isointense to the brain on T1-weighted Spin Echo images, isointense to hypointense to the brain on T2-weighted Fast Spin Echo sequences and hypointense to the brain on Flair sequence. After MRI study fine needle aspiration biopsy of the tumors was performed. On the basis of the cytological examination fibrosarcomas with of moderate malignancy were diagnosed.

Stem cells in dentistry--review of literature.

Stem cells have been successfully isolated from a variety of human and animal tissues, including dental pulp. This achievement marks progress in regenerative dentistry. This article reviews the latest improvements made in regenerative dental medicine with the involvement of stem cells. Although, various types of multipotent somatic cells can be applied in dentistry, two types of cells have been investigated in this review. Dental pulp cells are classified as: DPSCs, SCAPs and SHEDs.The third group includes two types of cell associated with the periodontium: PDL and DFPC. This review aims to systematize basic knowledge about cellular engineering in dentistry.

Most commonly used sequences and clinical protocols for brain and spine magnetic resonance imaging allowing better identification of pathological changes in dogs.

Magnetic resonance imaging is the best imaging modality for the brain and spine. Quality of the received images depends on many technical factors. The most significant factors are: positioning the patient, proper coil selection, selection of appropriate sequences and image planes. The present contrast between different tissues provides an opportunity to diagnose various lesions. In many clinics magnetic resonance imaging has replaced myelography because of its noninvasive modality and because it provides excellent anatomic detail. There are many different combinations of sequences possible for spinal and brain MR imaging. Most frequently used are: T2-weighted fast spin echo (FSE), T1- and T2-weighted turbo spin echo, Fluid Attenuation Inversion Recovery (FLAIR), T1-weighted gradient echo (GE) and spin echo (SE), high-resolution three-dimensional (3D) sequences, fat-suppressing short tau inversion recovery (STIR) and half-Fourier acquisition single-shot turbo spin echo (HASTE). Magnetic resonance imaging reveals neurologic lesions which were previously hard to diagnose antemortem.

Magnetic resonance protocols in equine lameness examination, used sequences, and interpretation.

Magnetic resonance is a great diagnostic tool in equine lameness examination. Its value is most significantly visible in evaluating distal extremities. Problems with podotrochlear apparatus, laminitis or distal interphalangeal joint osteoarthritis are the most common disorders diagnosed in equine patients. Without using magnetic resonance it was impossible to clearly assess which structures are involved in each of these diseases. One of the most important things in MRI is the choice of sequence. Most commonly used are T1 GE, T2 FSE, STIR and T2* GE, in sagittal, transverse and dorsal planes. To make a reliable diagnosis it is important to compare findings in all these sequences.