A Quantitative Method for the Evaluation of Deep Vein Thrombosis in a Murine Model Using Three-Dimensional Ultrasound Imaging

Deep vein thrombosis (DVT) is a life-threatening condition that can lead to its sequelae pulmonary embolism (PE) or post-thrombotic syndrome (PTS). Murine models of DVT are frequently used in early-stage disease research and to assess potential therapies. This creates the need for the reliable and easy quantification of blood clots. In this paper, we present a novel high-frequency 3D ultrasound approach for the quantitative evaluation of the volume of DVT in an in vitro model and an in vivo murine model. The proposed method involves the use of a high-resolution ultrasound acquisition system and semiautomatic segmentation of the clot. The measured 3D volume of blood clots was validated to be correlated with in vitro blood clot weights with an R2 of 0.89. Additionally, the method was confirmed with an R2 of 0.91 in the in vivo mouse model with a cylindrical volume from macroscopic measurement. We anticipate that the proposed method will be useful in pharmacological or therapeutic studies in murine models of DVT.

Targeted PERK inhibition with biomimetic nanoclusters confers preventative and interventional benefits to elastase-induced abdominal aortic aneurysms

Abdominal aortic aneurysm (AAA) is a progressive aortic dilatation, causing ∼80% mortality upon rupture. Currently, there is no approved drug therapy for AAA. Surgical repairs are invasive and risky and thus not recommended to patients with small AAAs which, however, account for ∼90% of the newly diagnosed cases. It is therefore a compelling unmet clinical need to discover effective non-invasive strategies to prevent or slow down AAA progression. We contend that the first AAA drug therapy will only arise through discoveries of both effective drug targets and innovative delivery methods. There is substantial evidence that degenerative smooth muscle cells (SMCs) orchestrate AAA pathogenesis and progression. In this study, we made an exciting finding that PERK, the endoplasmic reticulum (ER) stress Protein Kinase R-like ER Kinase, is a potent driver of SMC degeneration and hence a potential therapeutic target. Indeed, local knockdown of PERK in elastase-challenged aorta significantly attenuated AAA lesions in vivo. In parallel, we also conceived a biomimetic nanocluster (NC) design uniquely tailored to AAA-targeting drug delivery. This NC demonstrated excellent AAA homing via a platelet-derived biomembrane coating; and when loaded with a selective PERK inhibitor (PERKi, GSK2656157), the NC therapy conferred remarkable benefits in both preventing aneurysm development and halting the progression of pre-existing aneurysmal lesions in two distinct rodent models of AAA. In summary, our current study not only establishes a new intervention target for mitigating SMC degeneration and aneurysmal pathogenesis, but also provides a powerful tool to facilitate the development of effective drug therapy of AAA.

Progress in murine models of ruptured abdominal aortic aneurysm

Abdominal aortic aneurysm (AAA) is a focal dilation of the aorta that is prevalent in aged populations. The progressive and unpredictable expansion of AAA could result in aneurysmal rupture, which is associated with ~80% mortality. Due to the expanded screening efforts and progress in diagnostic tools, an ever-increasing amount of asymptomatic AAA patients are being identified yet without a cure to stop the rampant aortic expansion. A key barrier that hinders the development of effective AAA treatment is our incomplete understanding of the cellular and molecular basis of its pathogenesis and progression into rupture. Animal models provide invaluable mechanistic insights into AAA pathophysiology. However, there is no single experimental model that completely recapitulate the complex biology behind AAA, and different AAA-inducing methodologies are associated with distinct disease course and rupture rate. In this review article, we summarize the established murine models of ruptured AAA and discuss their respective strengths and utilities.

Transection of direct anterior thalamic afferents from the hippocampus: effects on activity and active avoidance in rats

This investigation demonstrates the importance of the direct hippocampo-anterior thalamic component of the postcommissural fornix in the control of general locomotion and active avoidance. Transection of anterior thalamic afferents from the hippocampal formation (subicular cortex), at the point where they exit from the fornix posterior to the septum, is sufficient to enhance bidirectional active avoidance acquisition and increase general activity. This transection may also interrupt fibers to or from other thalamic nuclei and the anterior septum. However, destruction of connections of the anterior septum with the hippocampus, habenula, and thalamus by transection in the coronal plane anterior to the descending fornix columns, without damage to the subiculothalamic fibers, increases general activity levels without damage to the subiculothalamic fibers, increases general activity levels without affecting active avoidance behavior. The activity increase in this case resembles that seen after septal lesions rather than that seen after hippocampal lesions. Thus, destruction of a single fornix component contributing afferents to the anterior thalamic nuclei reproduces at least part of the hippocampal syndrome. This suggests that these fibers contribute significantly to the control of these behaviors and may mediate active avoidance changes resulting from hippocampal and fornix damage.

Nucleus accumbens lesions reduce amphetamine hyperthermia but not hyperactivity

Electrolytic lesions of the nucleus accumbens were found to produce an increase in spontaneous locomotion; additionally, these lesions attenuated the hyperthermic, but not the hyperkinetic, actions of d-amphetamine. These results suggest that while dopamine release from the mesolimbic system may underlie amphetamine-induced hyperthermia, other structures must also be involved in amphetamine-induced hypermotility.

Comparison of regional serotonin levels and turnover in the brain of naturally high and low aggressive rats

Rats, matched by weight and goal approach, were tested for aggressiveness using a food-competition paradigm. Those winning and those losing all of their matches were designated as high and low aggressive, respectively. A third group of randomly selected rats never fought and were used as a control for the fighting experience. Half of the rats were used to determine serotonin (5-HT) and 5-hydroxyindoleacetic acid (5-HIAA) levels in discrete brain regions. The other half were used to estimate 5-HT turnover in the same brain regions. High and low aggressive rats did not differ with regard to 5-HT or 5-HIAA levels, but high aggressive rats showed faster 5-HT turnover than low aggressive rats. The turnover differences reached statistical significance in only two of the 3 brain regions examined: (a) all structures (minus olfactory bulbs) rostral to the level of the anterior commissure, and (b) the brain stem (hypothalamus-midbrain-medulla). The observed differences cannot be attributed to differing behavioral experiences since the high and low aggressive groups pooled did not differ from the no-fighting control. These findings are discussed with respect to the involvement of serotonin in rat intraspecies aggression.

Intracranial self-stimulation effects along the route of the nigro-striatal bundle

Recent evidence suggesting a possible dopaminergic nigro-striatal substrate of self-stimulation led us to map this route for both self-stimulation and stimulus-bound motor effects. The results of 128 electrode placements show that the route of the nigro-striatal projection supports strong self-stimulation effects from the substantia nigra to the ento-peduncular nucleus. Beyond this level, such effects disappear. Our results indicate that the striatum itself is neutral with regard to reinforcement, and suggest that such apparent neutrality cannot be ascribed to motor or other artifacts. These findings require a reappraisal of the hypothesis of a dopaminergic self-stimulation system, although they are not in conflict with the idea that dopaminergic manipulations may affect self-stimulation through some more general regulatory influence on operant responding.