Rabbit Aorta Research Articles

Synthetic Flavonoid 3,7-Dihydroxy-Isoflav-3-Ene (DHIF) Reduces In-Stent Restenosis in an Atherosclerotic Watanabe Heritable Hyperlipidemic Rabbit Stent Model.

Inflammation is a major component of the pathogenesis of atherosclerosis and the formation of in-stent restenosis (ISR). A novel flavonoid, DHIF, attenuates reactive oxygen species and nf-κB signaling and has potential to limit ISR via antioxidant action. While current drug eluting stents (DESs) perform well in clinical practice, new therapies to prevent ISR without dependance on cytotoxic drugs are warranted. Our objective was to test whether DHIF reduces ISR in a hyperlipidemic rabbit aorta model of ISR via attenuated inflammatory responses. WHHL rabbit aortas (n = 24) were denuded. Six weeks after injury, stents were implanted into the denuded aortas. DHIF was dissolved in carboxymethyl cellulose (CMC) and administered orally with two doses. CMC served as a control. The animals were sacrificed six weeks after stenting. ISR was evaluated from stent histomorphometry and immunohistology was used to assess the inflammatory and antiproliferative effects of the treatment. ISR was reduced from 20.9 ± 3.0% in controls to 15.2 ± 2.4% (p = 0.0009) and 16.4 ± 2.1% (p = 0.004) in the low- and high-dose groups, respectively. The neointimal area covered by macrophages was 32 ± 9.3% in the controls, 17.2 ± 5.9% (p = 0.005) in the low-dose group and 19.4 ± 7.9% (p = 0.008) in the high-dose group. DHIF significantly reduces ISR and local inflammation in stented arterial regions and could be used to reduce ISR when bare metal stents are used. Targeting local inflammation in the arterial wall may provide a way to reduce ISR in a clinical setting and further studies are warranted.

Impact of Diabetic Condition on the Remodeling of In Situ Tissue-Engineered Heart Valves.

Most in situ tissue-engineered heart valve (TEHV) evaluation studies are conducted in a healthy physical environment, which cannot accurately reflect the specific characteristics of patients. In this study, we established a diabetic rabbit model and implanted decellularized extracellular matrix (dECM) into the abdominal aorta of rabbits through interventional surgery with a follow-up period of 8 weeks. The results indicated that dECM implants in diabetic rabbits exhibited poorer endothelialization and more severe fibrosis compared to those in healthy animals. Furthermore, mechanistic studies revealed that high glucose induced endothelial cell (EC) apoptosis and impeded their proliferation and migration, accompanied by an increase in reactive oxygen species (ROS) concentration and a decrease in the nitric oxide (NO) level. High glucose also led to elevated ROS levels and an increased expression of inflammatory factors and transforming growth factor β1 (TGF-β1) in macrophages, contributing to fibrosis. These findings suggest that oxidative-stress-mediated mechanisms are likely the primary pathways affecting heart valve repair and regeneration under diabetic conditions. Therefore, future design and evaluation of TEHVs may concern more patient-specific circumstances.

Vasorelaxant mechanisms of the antidiabetic anagliptin in rabbit aorta: roles of Kv channels and SERCA pump.

The present study investigated the vasorelaxant mechanisms of an oral antidiabetic drug, anagliptin, using phenylephrine (Phe)-induced pre-contracted rabbit aortic rings. Arterial tone measurement was performed in rabbit thoracic aortic rings. Anagliptin induced vasorelaxation in a dose-dependent manner. Pre-treatment with the classical voltagedependent K+ (Kv) channel inhibitors 4-aminopyridine and tetraethylammonium significantly decreased the vasorelaxant effect of anagliptin, whereas pre-treatment with the inwardly rectifying K+ (Kir) channel inhibitor Ba2+, the ATP-sensitive K+ (KATP) channel inhibitor glibenclamide, and the large-conductance Ca2+-activated K+ (BKCa) channel inhibitor paxilline did not attenuate the vasorelaxant effect. Furthermore, the vasorelaxant response of anagliptin was effectively inhibited by pre-treatment with the sarco/endoplasmic reticulum Ca2+-ATPase (SERCA) pump inhibitors thapsigargin and cyclopiazonic acid. Neither cAMP/protein kinase A (PKA)-related signaling pathway inhibitors (adenylyl cyclase inhibitor SQ 22536 and PKA inhibitor KT 5720) nor cGMP/protein kinase G (PKG)-related signaling pathway inhibitors (guanylyl cyclase inhibitor ODQ and PKG inhibitor KT 5823) reduced the vasorelaxant effect of anagliptin. Similarly, the anagliptin-induced vasorelaxation was independent of the endothelium. Based on these results, we suggest that anagliptin-induced vasorelaxation in rabbit aortic smooth muscle occurs by activating Kv channels and the SERCA pump, independent of other vascular K+ channels, cAMP/PKA- or cGMP/PKG-related signaling pathways, and the endothelium.

Induction of Controllable Vortex Flow in a New Aorta Stenosis Model for Potential Aorta Mechanobiology Study: A Flow Simulation Platform

Background: Abdominal aortic aneurysms (AAA) are common, particularly among individuals over age 65, with a prevalence of 9%. To better understand the natural history of AAAs, one critical knowledge gap must be filled to elucidate the role of vortical flow in vascular degradation and thrombosis formation. We aimed to induce various types of vortical flow with aneurysm-like hemodynamic environments using a novel aorta stenosis model. Such a model will enable us to investigate the interplays between disturbed hemodynamics and vascular pathological remodeling. Methods: In this study, the hemodynamics and geometry of the aorta in rabbits were used to simulate the physiological flow conditions after two adjacent stenoses were created virtually with varying degrees of area reduction (30-70%) and spacing (5-6.8 mm). A physiological blood flow (rate) waveform measured in rabbits using ultrasound Doppler (normalized to 3.0 mL/s) was prescribed to the inlet (i.e., descending aorta), and zero pressure boundary conditions were applied at two outlets (i.e., iliac arteries). 3D computational fluid dynamics (CFD) simulation in five different stenosis configurations was performed using commercial software (Fluent, Version 20, Ansys Inc., PA). In-house software assessed the evolution of flow vortices over three distinct regions post stenosis using an established method. The total volume of vortex flow, the number of vortices, and the phase-to-phase overlap of vortex flows within different post-stenosis regions were derived to characterize the vortex flow. Results: Quantitative and qualitative flow assessments were performed for all five CFD models. Firstly, in all models, we found consistent patterns of the three vortex flow parameters, indicating that the adjacent stenoses induced three different hemodynamic zones in the post-stenosis regions, namely, stable vortical flow (after first stenosis), transient flow (after second stenosis), unstable vortical flow (further distal to second stenosis). Moreover, increased stenosis degree or reduced spacing led to reduced vortex flow number but increased total volume of vortex flow. The distinctions of the three regions were most significant in the model with 50% and then 30% stenoses, and with a 5 mm (center-to-center) spacing between two stenoses. Conclusions: CFD simulations can offer a powerful tool to predict complex flows using subject-specific vasculature. Such a flow simulation platform is valuable for guiding experimental design or therapy in various diseases. We demonstrated that it is feasible to adjust and achieve multiple types of vortical flows with the novel stenosis model. The three zones with distinct hemodynamic environments allow us to investigate the vascular remodeling regulated by the specifics of the eddies. Our ongoing work is implementing optimized aorta stenosis models to preclinical or in vitro studies to reveal the interplays between varying disturbed flow and aneurysm remodeling. We acknowledge funding support from NIH/NIBIB (R01-EB029570A1) and the Health Research Institute of Michigan Technological University. This is the full abstract presented at the American Physiology Summit 2024 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.

Empagliflozin, an SGLT2i, relaxes coronary smooth muscle at pharmacological concentrations

Morbidity and mortality due to heart failure with preserved ejection fraction (HFpEF) is increasing and there are no universally recognized strategies for treatment. Sodium-glucose co-transporter type 2 inhibitors (SGLT2i), such as Empagliflozin, have been shown to reduce myocardial stiffness and improve coronary microvascular performance, but mechanisms are unclear. Previous studies in rabbit aorta and rat mesentery suggest Empagliflozin relaxes smooth muscle through activation of K+ channels. This study investigated the effects of therapeutic and pharmacological concentrations of Empagliflozin (10-300 μM) on the isometric tension of left circumflex (CFX) coronary arteries from Yorkshire swine. We tested the hypothesis that Empagliflozin would relax coronary smooth muscle via a concentration-dependent manner, involving K+ channels. CFX arteries were dissected, cleaned of adventitia, cut into 3 mm rings (n = 16), and mounted in organ baths containing Krebs-Henseleit buffer (37 °C) for isometric tension studies. Each CFX segment was adjusted to optimal preload (~3 g passive tension) as determined by <10 % change in active tension in response to 60 mM KCl. In order to determine whether Empagliflozin caused relaxation and, if so, by what mechanism, rings were contracted with either 30 mM K+ or the thromboxane mimetic U46619 (1 μM). Once tension plateaued, Empagliflozin (10-300 μM) was added in increasing concentrations. Therapeutic concentrations of Empagliflozin (10-30 μM), elicited no significant relaxation. Pharmacologic concentrations of Empagliflozin (≥100 μM) caused significant relaxation from ~15 ± 11% to ~45 ± 10% in response to 100 μM vs. 300 μM Empagliflozin, respectively. Relaxation was not different between rings contracted with K+ or U46619, suggesting membrane hyperpolarization via K+ channels is not involved. Our results represent the first study of the effects of Empagliflozin on coronary smooth muscle reactivity. Data support the idea that relaxation of coronary smooth muscle by Empagliflozin occurs at supra-pharmacologic concentrations in vitro, but K+ channel activation appears to be an unlikely mechanism. This project was supported by National Institutes of Health grant R01 HL158723. This is the full abstract presented at the American Physiology Summit 2024 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.

Regular transient limb ischemia improves endothelial function and inhibits endothelial cell apoptosis to prevent atherosclerosis in rabbit

AimsRegular transient limb ischemia (RTLI) can prevent atherosclerosis (AS) progression in hypercholesterolemic rabbits. This study aimed to investigate the minimum effective intensity and possible mechanisms of RTLI for preventing atherosclerosis.MethodsEighty rabbits were divided into eight groups: normal (N), high cholesterol (H), three RTLI [three RTLI cycles every other day (R3qod), three RTLI cycles daily (R3qd), and six RTLI cycles daily (R6qd), each cycle of RTLI included 5 min of limb ischemia followed by 5 min limb reperfusion], and three correlated sham RTLI [sham ischemia for 30 min once every other day (S3qod), sham ischemia for 30 min once daily (S3qd), and sham ischemia for 60 min once daily (S6qd)]. Rabbits in group N were kept normally, while the others were fed 1% cholesterol diet for 12 weeks. The RTLI and sham RTLI groups were received RTLI or sham RTLI procedure, respectively. The plaque area in the thoracic aorta was determined by oil red O staining, and quantifying the ratio of plaque area to intimal area (PA/IA). Endothelium-dependent and -independent relaxation were also determined. Endothelial cell were isolated from abdominal aorta of rabbits, and the apoptosis ratio was detected using flow cytometry.ResultsThe PA/IA and early apoptotic cell ratio was significantly lower as well as the endothelium-dependent relaxation response was higher in group R6qd than those in groups H and S6qd, while those in the R3qod group was not significantly different from those in groups H and S3qod, as well as those in the R3qd group showed no significant difference compared to those in groups H and S3qd.ConclusionsSix cycles of RTLI daily was the optimal effective intensity to prevent AS progression in rabbits. Endothelial function improvement and apoptosis inhibition might contribute to the anti-AS effects.

Exploring the effects of Nano-liposomal TGF-β1 on induced pluripotent stem Cell-Derived vascular smooth muscle cells in Tissue-Engineered vascular graft; an in vivo study

This study explores the impact of liposomal Transforming Growth Factor β1 (TGF-β1) on phenotypic switching in Vascular Smooth Muscle Cells (VSMCs) derived from induced pluripotent stem cells (iPSCs) for arterial tissue engineering. We present an innovative approach to reducing graft waiting periods effectively. Using a biomimetic perfusion system, biological scaffolds were developed from sheep's carotid artery to create Tissue-Engineered Vessels (TEVs). VSMCs derived from rabbit iPSCs were reseeded onto these TEVs to promote proliferation. TGF-β1 was encapsulated in liposomes using the thin-film hydration method to enhance VSMC growth. The controlled release of TGF-β1 from these liposomes was quantified through enzyme-linked immunosorbent assay (ELISA). Nano-liposomal TGF-β1 was loaded into the scaffolds at a concentration of 50 ng/mL, with the release monitored through ELISA. The proliferative activity of VSMCs was evaluated using the CCK8 kit. Techniques such as real-time PCR, Western blot, Immunohistochemistry, and Flowcytometry were employed to assess VSMC phenotypic switching. Liposomal TGF-β1 treatment led to a 122.30 % increase in cell proliferation rate in TEVs compared to the control group, indicating no cytotoxicity. ELISA results confirmed a controlled and sustained release of liposomal TGF-β1. Furthermore, we demonstrated the efficacy of liposomal TGF-β1 for sustained delivery over an extended period by implanting the grafts in rabbit aortas and monitoring their performance for four weeks. Our findings highlight the role of Nano-liposomal TGF-β1 in inducing phenotypic transformation within TEVs. This research underscores the promising therapeutic potential of Nano-liposomal TGF-β1 in advancing blood vessel tissue engineering, offering novel pathways for clinical application and addressing the critical need for improved vascular graft outcomes. In conclusion, our study showcases the synergy between a biomimetic environment and Nano-liposomal TGF-β1 on rabbit induced pluripotent stem cell-derived VSMCs, emphasizing the significant increase in SMC proliferation, controlled release of TGF-β1, successful graft implantation, and the pioneering approach in arterial tissue engineering through the development of TEVs from sheep carotid arteries.

Medical Constituents of Ajwain (Trachyspermum ammi) for Human Benefits

Ajwain seed analysis has revealed it to contain fiber (11.9%), carbohydrates (38.6%), tannins, glycosides, moisture (8.9%), protein (15.4%), fat (18.1%), saponins, flavone and mineral matter (7.1%) containing calcium, phosphorous, iron and nicotinic acid. Ajwain fruits yield 2% to 4% brownish essential oil, with thymol as the major constituent (35% to 60%). The non-thymol fraction (thymine) contains para-cymene, γ-terpenine, α- and β-pinenes, diketene, α-terpinene, and carvacrol. Minute amounts of camphene, myrcene, and α-3-carene also have been found in the plant. Alcoholic extracts contain a highly hygroscopic saponin. From the fruits, a yellow, crystalline flavone and a steroid-like substance has been isolated and it also contains 6-O-β-glucopyranosyloxythymol, glucoside and yields 25% oleoresin containing 12% volatile oil (thymol, γ-terpinene, para-cymene, and α- and β-pinene). The principal oil constituents of T. Ammi are carvone (46%), limonene (38%), and dillapiole (9%). Ajwain is administered for curing stomach disorders, a paste of crushed fruits is applied externally for relieving colic pains; and a hot and dry fomentation of the fruits is applied on chest for asthma. Therapeutic uses of T. Ammi fruits include; stomachic, carminative and expectorant, antiseptic and amoebiasis, antimicrobial. Seeds soaked in lemon juice with P runs Amygdalus (badan) are given in curing amenorrhea and it is also used as antipyretic, febrifugal and in the treatment of typhoid fever. The antihypertensive effect of T. Ammi administered intravenously in vivo, and the antispasmodic and bronchodilation actions in vitro showed that calcium channel blockade has been found to mediate the spasmolytic effects of plant materials and it is being considered that this mechanism contributed to their observed result and supported the traditional use of T. Ammi in hyperactive disease states of the gut such as colic and diarrhea as well as in hypertension. Ajwain seeds revealed significant reduction of cough number which may be a result of its potent antitussive effect. The bronchodilator effect of decocted extract of Ajwain on the asthmatic patients’ airways was examined in a subsequent trial study. According to the results, the extract has a relatively bronchodilator effect on asthmatic airways compared to the effect of Theophylline at concentrations used. Ajwain was attributed to have diuretic and antilithiatic activity in ethnopharmacological reports. Accordingly, a human study was performed and in which, seeds of Ajwain were decocted in milk and given orally to volunteers suffering from urinary stone for a nine days period. The results were reported satisfactory against pure ca-oxalate stone. Another activity which has been proved for Ajwain is the antihyperlipidemic property. An in vivo study revealed that Ajwain seeds powder is extensively effective on lipid profile and can decrease total cholesterol, LDL-cholesterol, triglycerides and total lipids. Moreover, organic extract of seeds reduced atherogenic index and increased the level of HDL-cholesterol in albino rabbits. Ajwain was evaluated for the potentiality of antihypertensive and antispasmodic activity. In the related investigation, the aqueous-methanolic extract of the seeds caused a dose dependent decrease in arterial blood pressure in anaesthetized animal models. Furthermore, inhibitory effect on the K+-induced contractions was seen in isolated rabbit aorta and jejunum preparations during the application of Ajwain extract. These findings prove the potential antihypertensive and antispasmodic activity of Ajwain.

Comparison of the Effect of Kombucha and Vitamin C on Coronary Arteries in Rabbits Exposed to Lead and High-cholesterol Diet

Background: Vitamin C and kombucha contain a high amount of glucuronic acid that can prevent cholesterol accumulation and convert cholesterol to a more water-soluble compound. Objectives: The aim of this study was to compare the effects of kombucha and vitamin C on the coronary arteries and aorta of male rabbits exposed to lead acetate fed with a high-cholesterol diet. Methods: Forty male rabbits were divided randomly into four groups of 10 animals. Group 1 served as a control group. Rabbits in group 2 received water containing 547 ppm of lead acetate and a high-cholesterol diet (1%). Group 3 received water containing 547 ppm lead acetate and a high-cholesterol diet (1%) in combination with ascorbic acid (500 mg/kg), and group 4 rabbits were treated with water containing 547 ppm lead acetate and kombucha extract (10 ml/kg) for 40 days orally on a high-cholesterol diet (1%). Results: The results showed that in groups 3 and 4, no significant atherosclerotic plaques could be detected in coronary arteries, compared to the control animals. However, large atherosclerotic plaques were observed in the aortas of those treated only with kombucha. The data were analyzed using analysis of variance (ANOVA) statistical methods. The mean ± standard error of the mean (SEM) triglyceride (TG) serum levels in groups 1, 2, 3, and 4 were 122.70 ± 66.77, 280.60 ± 88.66, 120.10 ± 8.33, and 107.86 ± 8.61 mg/dL, respectively. The mean ± SEM TG serum levels in groups 1, 2, 3, and 4 were 67.80 ± 10.33, 67.90 ± 10.10, 60.80 ± 8.16, and 58.71 ± 4.78 mg/dL, respectively. The mean ± SEM TG serum levels in groups 1, 2, 3, and 4 were 194.50 ± 6.58, 182.60 ± 13.75, 178.30 ± 18.01, and 166.00 ± 7.65 mg/dL, respectively. P-values for low-density lipoprotein (LDL), high-density lipoprotein (HDL), and TG were reported as P < 0.001, P = 0.077, and P < 0.001, respectively. Conclusions: It could be concluded that kombucha, unlike vitamin C, cannot prevent the formation of large plaques in the aorta, although it seems that it can prevent atherosclerotic lesions in coronary arteries. Therefore, further studies are required to evaluate the long-term use of kombucha to assess whether higher doses are beneficial in preventing atherosclerotic events or not.

Magnesium Orotate Influence on Thoracic Aorta in Laboratory Rabbits Receiving Levofloxacin

INTRODUCTION. Fluoroquinolones are antibacterial agents associated with adverse drug reactions (ARDs), including aortic lesions; this ARD risk limits the use of fluoroquinolones. Moreover, fluoroquinolones have been reported to induce lesions in other connective tissues (cartilage, tendons), associated with magnesium deficiency.AIM. The study aimed to analyse the effects of magnesium orotate on the thoracic aorta in laboratory rabbits treated with levofloxacin.MATERIALS AND METHODS. The study randomised laboratory rabbits into 3 groups of 10 animals each to receive oral doses of either the carrier solution (control group), or 150 mg/kg/day levofloxacin (levofloxacin group), or 150 mg/ kg/day levofloxacin and 140 mg/kg/day magnesium orotate (levofloxacin/magnesium group). After 14 days of treatment, venous blood samples were taken to determine the serum levels of magnesium, matrix metalloproteinase-9 (MMP-9), and tissue inhibitor of matrix metalloproteinase-1 (TIMP-1), as well as MMP-9 to TIMP-1 ratios. The authors conducted morphological and mechanical characterisation of thoracic aorta samples; the mechanical characterisation involved uniaxial tensile testing. Data are presented as the mean and standard deviation values.RESULTS. The study did not detect any changes in the serum MMP-9, TIMP-1, and magnesium levels or in the MMP-9/TIMP-1 ratios. The authors identified foci of moderate elastic fibre fragmentation in the aortic media in 5 of 10 aortic samples from the levofloxacin group, in 1 of 10 samples from the levofloxacin/magnesium group, and in none from the control group (p=0.013). Rabbits from the levofloxacin group had significantly fewer medial elastic membranes than the others (p=0.015; vs the control group: p=0.022), and their elastic mem

Medical Constituents of Ajwain (Trachyspermum ammi) for Human Benefits

Ajwain seed analysis has revealed it to contain fiber (11.9%), carbohydrates (38.6%), tannins, glycosides, moisture (8.9%), protein (15.4%), fat (18.1%), saponins, flavone and mineral matter (7.1%) containing calcium, phosphorous, iron and nicotinic acid. Ajwain fruits yield 2% to 4% brownish essential oil, with thymol as the major constituent (35% to 60%). The non-thymol fraction (thymene) contains para-cymene, γ-terpenine, α- and β-pinenes, dipentene, α-terpinene, and carvacrol. Minute amounts of camphene, myrcene, and α-3-carene also have been found in the plant. Alcoholic extracts contain a highly hygroscopic saponin. From the fruits, an yellow, crystalline flavone and a steroid-like substance has been isolated and it also contains 6-O-β-glucopyranosyloxythymol, glucoside and yields 25% oleoresin containing 12% volatile oil (thymol, γ-terpinene, para-cymene, and α- and β-pinene). The principal oil constituents of T. ammi are carvone (46%), limonene (38%), and dillapiole (9%). Ajwain is administered for curing stomach disorders, a paste of crushed fruits is applied externally for relieving colic pains; and a hot and dry fomentation of the fruits is applied on chest for asthma. Therapeutic uses of T. ammi fruits include; stomachic, carminative and expectorant, antiseptic and amoebiasis, antimicrobial. Seeds soaked in lemon juice with P runus amygdalus (badam) are given in curing amenhorroea and it is also used as antipyretic, febrifugal and in the treatment of typhoid fever. The antihypertensive effect of T. ammi administered intravenously in vivo, and the antispasmodic and bronchodilating actions in vitro showed that calcium channel blockade has been found to mediate the spasmolytic effects of plant materials and it is being considered that this mechanism contributed to their observed result and supported the traditional use of T. ammi in hyperactive disease states of the gut such as colic and diarrhea as well as in hypertension. Ajwain seeds revealed significant reduction of cough number which may be a result of its potent antitussive effect. The bronchodilatory effect of decocted extract of Ajwain on the asthmatic patients’ airways was examined in a subsequent trial study. According to the results, the extract has a relatively bronchodilatory effect on asthmatic airways compared to the effect of Theophylline at concentrations used. Ajwain was attributed to have diuretic and antilithiasis activity in ethnopharmacological reports. Accordingly, a human study was performed and in which, seeds of Ajwain were decocted in milk and given orally to volunteers suffering from urinary stone for a nine days period. The results were reported satisfactory against pure ca-oxalate stone. Another activity which has been proved for Ajwain is the antihyperlipidemic property. An in vivo study revealed that Ajwain seeds powder is extensively effective on lipid profile and can decrease total cholesterol, LDL-cholesterol, triglycerides and total lipids. Moreover, organic extract of seeds reduced atherogenic index and increased the level of HDL-cholesterol in albino rabbits. Ajwain was evaluated for the potentiality of antihypertensive and antispasmodic activity. In the related investigation, the aqueous-methanolic extract of the seeds caused a dose dependent decrease in arterial blood pressure in anaesthetized animal models. Furthermore, inhibitory effect on the K+-induced contractions was seen in isolated rabbit aorta and jejunum preparations during the application of Ajwain extract. These findings prove the potential antihypertensive and antispasmodic activity of Ajwain.

Awake rabbit model of ischemic spinal cord injury with delayed paraplegia: The role of ambient temperature.

Paraplegia after spinal cord ischemia is a devastating condition in the clinic. Here, we develop an awake rabbit model of spinal cord ischemia with delayed paraplegia and explore the influence of ambient temperature on the outcomes after injury. A total of 47 male rabbits were involved in the present study. Transient spinal cord ischemia was induced by occluding the infrarenal abdominal aorta of awake rabbits at different ambient temperatures. To find the optimal conditions for developing delayed paraplegia, hindlimb motor function after ischemia was evaluated between experiments. The onset and magnitude of ischemic injury varied with the ambient temperature maintained during the peri-ischemia period. More serious spinal cord injury occurred when ischemia was induced at higher temperatures. At 18°C, 25-minute ischemia resulted in 74% of rabbits developing delayed paraplegia. At a temperature of 28°C or higher, most of the animals developed acute paraplegia immediately. While at 13°C, rabbits usually regained normal motor function without paraplegia. This awake rabbit model is highly reproducible and will be helpful in future studies of delayed paraplegia after spinal cord ischemia. The ambient temperature must be considered while using this model during investigation of therapeutic interventions.

Improvement of Vascular Insulin Sensitivity by Ranolazine.

Ranolazine (RN) is a drug used in the treatment of chronic coronary ischemia. Different clinical trials have shown that RN behaves as an anti-diabetic drug by lowering blood glucose and glycosylated hemoglobin (HbA1c) levels. However, RN has not been shown to improve insulin (IN) sensitivity. Our study investigates the possible facilitating effects of RN on the actions of IN in the rabbit aorta. IN induced vasodilation of the abdominal aorta in a concentration-dependent manner, and this dilatory effect was due to the phosphorylation of endothelial nitric oxide synthase (eNOS) and the formation of nitric oxide (NO). On the other hand, IN facilitated the vasodilator effects of acetylcholine but not the vasodilation induced by sodium nitroprusside. RN facilitated all the vasodilatory effects of IN. In addition, IN decreased the vasoconstrictor effects of adrenergic nerve stimulation and exogenous noradrenaline. Both effects were in turn facilitated by RN. The joint effect of RN with IN induced a significant increase in the ratio of p-eNOS/eNOS and pAKT/AKT. In conclusion, RN facilitated the vasodilator effects of IN, both direct and induced, on the adrenergic system. Therefore, RN increases vascular sensitivity to IN, thus decreasing tissue resistance to the hormone, a key mechanism in the development of type II diabetes.

Comparison of arterial wall integration of different flow diverters in rabbits: The CICAFLOW study

Background and purposeNew coated flow diverters (FDs) claim antithrombotic properties and increased arterial wall integration. The aim of this study is to compare in vivo endothelial coverage of coated and uncoated FD in the context of different antiplatelet regimens. MethodsDifferent FDs (Silk Vista – SV, Pipeline with Shield technology – PED shield and Surpass Evolve – SE) were implanted in the aorta of rabbits, all 3 in each animal with 3 different antiplatelet regimens: no antiplatelet therapy, aspirin alone, or aspirin and ticagrelor. Four weeks after FD implantation, angiography, flat-panel CT, and optical coherence tomography (OCT) were performed before harvesting the aorta. Extensive histopathology analyses were performed including environmental scanning electron microscopy (ESEM), multiphoton microscopy (MPM) and histological staining with qualitative and/or quantitative assessment of device coverage. ResultsAll 23 FDs that were implanted remained patent without hyperplasia. Qualitative stent coverage assessment revealed that there were no statistically significant differences between the FD groups (p = 0.19, p = 0.45, p = 0.40, and p = 0.84 for OCT, ESEM, MPM and histology, respectively). Quantitative neointimal measurement of histological sections also showed similar results in all 3 FD groups (p = 0.70). However, there were significant differences between the 3 groups of antiplatelet regimens (p = 0.07) with a higher rate in the no antiplatelet group (p = 0.05 versus aspirin alone and p = 0.03 versus aspirin and ticagrelor). ConclusionOur study provides evidence that FD integration into the arterial wall is similar with coated (PED shield) and uncoated devices (SV, SE), regardless of the antiplatelet regimen. FD integration with specific surface coverage should be promoted. Trial registrationAPAFIS #2022011215518538.

Anti-inflammation-based treatment of atherosclerosis using Gliclazide-loaded biomimetic nanoghosts

In the study, a biomimetic platform for anti-inflammatory-based treatment of atherosclerotic plaque was developed. Gliclazide (GL) as an anti-inflammasome agent was encapsulated in PLGA nanoparticles (NP), which were coated by monocyte membrane using an extrusion procedure. The size and zeta potential of the nanoghost (NG) changed to 292 and – 10 nm from 189.5 to −34.1 in the core NP. In addition, the actual size of 62.5 nm with a coating layer of 5 nm was measured using TEM. The NG was also showed a sustained release profile with the drug loading content of about 4.7%. Beside to attenuated TNFα, decrease in gene expression levels of NLRP3, MyD88, NOS, IL-1β, IL-18 and caspases 1/3/8/9 in LPS-primed monocytes exposed to NG strongly indicated remarkable inflammation control. After systemic toxicity evaluation and pharmacokinetic analysis of NP and NG, intravenous NG treatment of rabbits with experimentally induced atherosclerosis revealed remarkably less plaque lesions, foam cells, lipid-laden macrophages, and pathological issues in tunica media of aorta sections. Higher expression of CD163 than CD68 in aorta of NG-treated rabbits strongly reveals higher M2/M1 macrophage polarization. The bio/hemocompatible, biomimetic and anti-inflammatory NG can be considered as a potential platform for immunotherapy of particularly atherosclerosis in the field of personalized medicine.

Pharmacological Basis for Antispasmodic, Bronchodilator, and Antidiarrheal Potential of Dryopteris ramosa (Hope) C. via In Vitro, In Vivo, and In Silico Studies.

Background:Dryopteris ramosa is used as an old treatment for several diseases. D. ramose fronds are eaten to treat gastrointestinal (GIT) issues and as an antibiotic. However, there is a dearth of literature justifying its traditional use. Aims and objectives: the current work used biological and molecular docking studies to support traditional usage and elucidate D. ramosa's multitarget mechanism. Materials and methods: Bioactive compounds were docked in silico. Force displacement transducers coupled with a power lab data gathering system examined the effects of compounds on rabbit jejunum, trachea, and aorta tissues. Albino mice and rats were used for in vivo studies. Results: Bioactive compounds interacted with inflammation, asthma, and diarrhea genes, according to in silico studies. D. ramosa crude extract (Dr.Cr) calmed impulsive contractions and K+ (80 mM)-provoked contractions in the jejunum and tracheal tissue dose-dependently, showing the presence of the Ca++ channel-blocking (CCB) effect, further verified by the rightward parallel shift of CRCs equivalent to verapamil. Polarity-based fractionation showed spasmolytic activity in Dr.DCM and muscarinic receptors mediated spasmogenic activity in the Dr.Aq fraction. Dr.Cr vasoconstricted the aortic preparation, which was totally blocked by an angiotensin II receptor antagonist. This suggests that Dr. Cr's contractile effect is mediated through angiotensin receptors. In rats and mice, it showed anti-inflammatory and antidiarrheal action. Conclusion: This study supports the traditional medicinal uses of D. ramosa against GIT disorders and may be an important therapeutic agent in the future.

HDL apoprotein immunization induces T cell-mediated venulitis and inflammation in aorta

The hypothesis that atherosclerotic processes are mostly caused by immune (autoimmune) mechanisms has recently been gaining attraction. At the same time, the autoimmune hypothesis of atherogenesis has not become generally accepted and requires additional evidence. Previously, we were able to induce changes in the aortic wall similar to those observed in the early stages of human atherosclerosis, and also to produce visceral obesity in normocholesterolaemic Wistar rats by a single immunization with human native high- or low-density lipoproteins. We also found that the immune response to native human HDL causes atherosclerosis-like lesions in the rabbit aorta, such as adipocyte and chondrocyte metaplasia, proteoglycan deposits, and leukocyte infiltration. Atherosclerosis-like lesions developed in the aorta of hnHDL-immunized rabbits against a background of normal blood LDL-cholesterol level. Thus, an immune response against HDL or LDL may be an independent cause of atherogenesis. The aim of this study was to test whether immunization with human HDL apoproteins (apoA1 and apoE proteins) would induce atherosclerosis-like lesions in the aorta of normocholesterolemic Wistar rats. HDL apoproteins were isolated from human or rat plasma. Wistar rats (n = 5) aged 2 months were used for immunization with human HDL apoproteins. HDL apoproteins were administered as a single intradermal injection of 100 mg per rat in incomplete Freund’s adjuvant. Control rats were injected subcutaneously with incomplete Freund’s adjuvant (n = 5). Rats were dissected 25 weeks after immunization. Rat aorta sections were stained with hematoxylin and eosin for light microscopy. T lymphocytes infiltration was determined by immunohistochemical staining with FITC-labeled antibodies specific to rat CD3. CD3 + T lymphocytes were detected using an Olympus BX53 fluorescent microscope. The level of antibodies to human and rat HDL apoproteins was determined by indirect enzyme-linked immunosorbent assay. Immunization with HDL apoproteins induced a T cell mediated immune response without production of autoantibodies to HDL apoproteins. The aortic intima and adventitia were infiltrated with T lymphocytes in rats immunized with HDL apoproteins. Pronounced T lymphocytic infiltration was found in all layers of the vein wall in rats immunized with human HDL apoproteins. Thus, immunization with HDL apoproteins causes T cell mediated inflammation of the aorta and venulitis.

Evaluation of a Rabbit Model of Vascular Stent Healing: Application of Optical Coherence Tomography.

Percutaneous coronary intervention (PCI) is a management strategy for symptomatic obstructive coronary artery disease (CAD). Despite advancements, in-stent restenosis (ISR) still imparts a 1-2% annual rate of repeat revascularization-a focus of ongoing translational research. Optical coherence tomography (OCT) provides high resolution virtual histology of stents. Our study evaluates the use of OCT for virtual histological assessment of stent healing in a rabbit aorta model, enabling complete assessment of intraluminal healing throughout the stent. ISR varies based on intra-stent location, stent length, and stent type in a rabbit model-important considerations for translational experimental design. Atherosclerosis leads to more prominent ISR proliferation independent of stent-related factors. Therabbit stent model mirrors clinical observations, while OCT-based virtualhistology demonstrates utility for pre-clinical stent assessment. Pre-clinical models should incorporate clinical and stent factors as feasible to maximize translation to clinical practice.

Desipramine enhances the stability of atherosclerotic plaque in rabbits monitored with molecular imaging.

Acid sphingomyelinase (ASM) promotes atherogenesis and acute cardiovascular events. We previously demonstrated ASM inhibitor desipramine attenuated oxidized-LDL-induced macrophage apoptosis in vitro. Here, we aim to determine whether ASM-mediated apoptosis in plaque improves stability in vivo. In this study, rabbits with abdominal aorta balloon injury and a 12-week high-cholesterol diet (HCD) were used to simulate an atherosclerotic plaque model. Atherosclerotic rabbits received oral administration of saline (Control group), atorvastatin (Ator group), or desipramine (DES group). ASM activity and ceramide level were measured by ultra-performance liquid chromatography (UPLC). Plaque morphology was assessed by histochemistry and immunohistochemistry. Apoptosis was evaluated by SPECT/CT imaging of 99mTc-duramycin uptake and TUNEL. We found that increasing ASM activity and ceramide level in atherosclerotic rabbits was abated by additional atorvastatin and desipramine treatment. Meanwhile, the DES and Ator groups were similar in plaque stability, with smaller plaque size, areas of macrophages, higher smooth muscle cell content, and decreased apoptosis and matrix metalloproteinase (MMP) activities relative to the Control group. 99mTc-duramycin uptake of rabbit aorta was significantly higher in Control than in the Normal group, while it was reduced by desipramine and atorvastatin administration. Moreover, the uptake of 99mTc-duramycin positively correlated with apoptotic cell number, macrophage infiltration, and plaque instability. The present study demonstrated that desipramine exerted plaque-stabilizing effects partially by suppressing apoptosis and MMP activity in a rabbit model. And 99mTc-duramycin SPECT/CT imaging allowed noninvasively monitoring of atherosclerotic disease and evaluation of anti-atherosclerotic therapy.

Non-invasive Assessment by B-Mode Ultrasound of Arterial Pulse Wave Intensity and Its Reduction During Ventricular Dysfunction.

Arterial pulse waves contain clinically useful information about cardiac performance, arterial stiffness and vessel tone. Here we describe a novel method for non-invasively assessing wave properties, based on measuring changes in blood flow velocity and arterial wall diameter during the cardiac cycle. Velocity and diameter were determined by tracking speckles in successive B-mode images acquired with an ultrafast scanner and plane-wave transmission. Blood speckle was separated from tissue by singular value decomposition and processed to correct biases in ultrasound imaging velocimetry. Results obtained in the rabbit aorta were compared with a conventional analysis based on blood velocity and pressure, employing measurements obtained with a clinical intra-arterial catheter system. This system had a poorer frequency response and greater lags but the pattern of net forward-traveling and backward-traveling waves was consistent between the two methods. Errors in wave speed were also similar in magnitude, and comparable reductions in wave intensity and delays in wave arrival were detected during ventricular dysfunction. The non-invasive method was applied to the carotid artery of a healthy human participant and gave a wave speed and patterns of wave intensity consistent with earlier measurements. The new system may have clinical utility in screening for heart failure.