Overview of large animal myocardial infarction models (review).

There are several experimental models for the in vivo investigation of myocardial infarction (MI) in small (mouse, rat) and large animals (dog, pig, sheep and baboons). The application of large animal models raises ethical concerns, the design of experiments needs longer follow-up times, requiring proper breeding and housing conditions, therefore resulting in higher cost, than in vitro or small animal studies. On the other hand, the relevance of large animal models is very important, since they mostly resemble to human physiological and pathophysiological processes. The first main difference among MI models is the method of induction (open or closed chest, e.g. surgical or catheter based); the second main difference is the presence or absence of reperfusion. The former (i.e. reperfused MI) allows the investigation of reperfusion injury and new catheter based techniques during percutaneous coronary interventions, while the latter (i.e. nonreperfused MI) serves as a traditional coronary occlusion model, to test the effects of new pharmacological agents and biological therapies, as cell therapy. The reperfused and nonreperfused myocardial infarction has different outcomes, regarding left ventricular function, remodelling, subsequent heart failure, aneurysm formation and mortality. Our aim was to review the literature and report our findings regarding experimental MI models, regarding the differences among species, methods, reproducibility and interpretation.

Computed tomographical (CT) anatomy of the thoracoabdominal cavity of the male turkey (Meleagris gallopavo).

In the present work, our goal was to match high-resolution computed tomography (CT) scans with cross-sectional anatomical pictures of the turkey (Meleagris gallopavo). Two male BUT 6 (a commercial line) turkeys were used. CT scans with 1 mm slice thickness were performed. The images covered the trunk from the level of the 9th cervical vertebra to the end of the coccyx. The anatomical sections and the CT scans were matched, and the important structures were identified and labelled on the corresponding pictures. The aim of this study was to create a reference for evaluating CT scans of avian species.

Magnetic resonance imaging technique for the examination of canine mammary tumours.

The aim of this study was to adapt the human magnetic resonance imaging (MRI) sequences for use in the routine examination of canine mammary glands. MRI was performed on 10, middle- to old-aged dogs of different breeds. It was found that T1- and T2-weighted spin echo, short T1 inversion recovery sequences and a gradient echo (GE) dynamic T1-weighted measurement made in the coronal and transversal planes were the most informative MR diagnostic methods for imaging canine mammary tumours. The static MR technique is the most detailed imaging modality for differentiating the tissue types in the substance of the mammary gland. The MRI findings were in close relationship with the histological result (five malignant mixed tumours and five cases of invasive ductal carcinoma). Using the GE dynamic contrast-enhanced sequence the morphological patterns as well as the kinetic parameters proved to be malignant. By the dynamic measurement technique initial information was obtained on the contrast enhancing properties, which are valuable factors during in vivo staging and in the prognostic work.

Comparison of the navicular region of newborn foals and adult horses by magnetic resonance imaging.

Magnetic resonance imaging (MRI) was tested for evaluation of the soft tissue structures of the equine digit in 16 limbs, derived from three adult warmblood horses and two newborn warmblood foals. The following measuring sequences were used in sagittal, transversal and coronal planes: spin echo, gradient echo, inversion recovery. The images were made with a 1.5 Tesla Siemens scanner in a CP-Helmholtz circular coil. To compare the visualization of the same tissue structures in adult and in newborn cases the limbs were imaged with the routinely used MRI sequences that are used for mature tissues. In newborn foals the bursa podotrochlearis could not be determined with the used sequences. For both the adult and newborn limbs the most visualization of the same tissue structures including the fluid spaces and growth plates were taken by the inversion recovery sequence. T2 sequence was very informative in adult cases but moderately in newborn foals.

Noninvasive characterization of the turkey heart performance and its relationship to skeletal muscle volume.

The cardiovascular capacity of turkeys is considerably affected by the selection procedure for meat production. To determine the body weight-related changes of some quantitative characteristics of the turkey heart function, serial measurements were carried out. BUT Big 6 turkeys (both sexes) were examined using whole-body magnetic resonance imaging (MRI) and spiral computer tomography (CT). Based on dynamic MRI examinations the following significant age- and sex-dependent quantitative differences were found. Means of the left ventricular stroke volumes were measured at the ages of 12 wk (males, 4.18 mL; females 2.89 mL), 16 wk (males, 6.56 mL; females, 4.14 mL), and 20 wk (males, 8.17 mL; females, 5.16 mL). Average cardiac output (CO) values were 0.76, 1.14, and 1.33 L/min for males and 0.58, 0.79,0.93 L/min for females. A statistically unproven age-dependent increasing tendency in the estimated relative CO value (skeletal muscle tissue volume measured by CT/CO unit) of male and female turkeys was found under sedentary conditions. These changes in the relative CO value and also the determined decrease of CO value related to body surface may, in theory, indicate a disadvantageous process that is more pronounced in males. The combined application of CT and MRI can be a powerful approach for studying the relationship between skeletal muscle development and heart capacity.