Edaravone attenuates sustained pial arteriolar vasoconstriction independently of the endothelial function after unclamping of an abdominal aorta in rabbits

Background

Cerebral blood flow (CBF) has direct impacts on the neuronal function and neurocognitive disorder. Oxidative stress from abdominal aortic surgery is important in the pathophysiology of CBF impairment. We investigated whether oxidative damage from abdominal aortic surgery is associated with reduced CBF and whether vascular endothelial dysfunction modifies these associations.

Methods

Rabbit closed cranial window preparation was used to measure changes in the pial arteriolar diameter after unclamping following abdominal aortic cross-clamping with an intravenous free radical scavenger, edaravone (control group, n=6; edaravone 10 μg/kg/min, n=6; 100 μg/kg/min, n=6). The pial vasodilatory responses to the topical application of acetylcholine (ACh) into the cranial window were investigated before abdominal aortic cross-clamping and after unclamping with the intravenous administration of edaravone (control group, n=6; edaravone 100 μg/kg/min, n=6).

Results

The aortic unclamping-induced vasoconstriction was significantly attenuated under the continuous infusion of edaravone at 100 μg/kg/min. The topical application of ACh after unclamping did not produce any changes in pial arteriolar responses in comparison to before aortic cross-clamping in the control or edaravone groups. The changes in the response to topical ACh after unclamping in the saline and edaravone groups did not differ to a statistically significant extent.

Conclusions

Free radicals during abdominal aortic surgery might have contracted cerebral blood vessels independently of the endothelial function in rabbits. The suppression of free radicals attenuated sustained pial arteriolar vasoconstriction after aortic unclamping. Thus, the free radical scavenger might have some brain protective effect that maintains the CBF independently of the endothelial function.

MicroRNA-29a-3p regulates abdominal aortic aneurysm development and progression via direct interaction with PTEN

Various research studies have been conducted in deducing the role of microRNAs (miRNAs) in the pathogenesis and physiological processes of various systematic diseases. This study aims at demonstration of the important role played by miR-29a-3p, through association with phosphatase and tensin homolog (PTEN), in the regulation of abdominal aortic aneurysm development and progression. Quantitative real-time polymerase chain reaction (RT-qPCR) examined miRNA-19a-3p and PMEPA1 expression in multiplied vascular smooth muscle cells (VSMCs). Cell transfection upregulated or downregulated the genes and cell counting kit-8 assay determined cellular viability. RT-qPCR detected cellular proliferation and cell death using the cell proliferation and apoptosis biomarkers Ki87 and proliferating cell nuclear antigen, caspase-8 and caspase-3, respectively. Furthermore, luciferase assay analyzed the luciferase activity and western blot analysis determined miRNA-19a-3p and PMEPA1 protein expression in proliferation and apoptosis biomarkers. TargetScan 4.2 online software (www.targetscan.org) was used to perform the bioinformatics analysis so as to forecast the putative targets of miR-29a-3p and PTEN. The results inferred that there was an increased expression of miRNA-29a-3p found in AAA-mimic cells with increased cellular viability and significant pathological apoptosis. Further, when the expression of miRNA-29a-3p was downregulated, it reduced the cell viability of AAA cells. On the basis of the gene interplays, it can be understood that the PTEN was directly targeted by miRNA-29a-3p so as to regulate the AAA progression. Thus, PTEN was found to strengthen the proliferation effect of miRNA-29a-3p in AAA cells. The current study thus shed more insights about the molecular mechanistic roles of miRNA-29a-3p and PTEN, opening doors for novel therapeutic approach to AAA.

Hypoxia-induced inflammation and purinergic signaling in cross clamping the human aorta

Open aortic surgery evokes a systemic inflammatory response and is associated with high morbidity and mortality. Purinergic signaling has been shown to be crucial for maintaining vascular integrity and attenuating inflammation related to hypoxia. The involvement of purinergic signaling in cross clamping of major human arteries is unknown. Our aim was to compare systemic inflammatory responses and hypoxia-induced purinergic signaling in patients undergoing either open infra-renal abdominal aortic repair or infra-inguinal revascularization. Pre- and 24 h post-operative blood samples were gathered from 6 patients undergoing aortic clamping and 6 similar patients undergoing common femoral artery cross-clamping. Using Biorad Multipex™ 21- and 27-panels 48 different cytokines, chemokines and growth factors were analyzed, in addition to circulating levels of ATP, ADP, CD39, CD73 and HIF-1α, and compared between the groups. Several inflammatory cytokines were elevated from baseline levels after aortic clamping, but not after femoral cross clamping. Most pronoun rises were seen in IL-6 (667 %, P = 0.016) and HGF (760 %, P = 0.016). HIF-1α values showed a steady increase after clamping of either artery unless the subject underwent blood transfusion. Despite an adequate increase in HIF-1α CD39 and CD73 activity decreased significantly after aortic clamping (P = 0.047 and P = 0.016, respectively). Aortic clamping is associated with a clear and strong systemic inflammatory response and impaired repair mechanisms in terms of purinergic signaling. Patients undergoing open aorta repair could benefit from pre-operative medical therapy, which enhances CD73 expression.

Protective role of heparin in the injury of the liver and kidney on the experimental model of ischemia/reperfusion

Background

Surgery of thoracoabdominal aortic aneurysms (TAAA) is associated with high incidence of serious complications. Ischemia/reperfusion (I/R) injury may be responsible for these complications. We investigated the effect of degree of anticoagulation on remote organ I/R injuries and whether heparin is protective against I/R injury in addition to its anticoagulant properties.

Methods

Spraque Dawley rats were used to determine both liver and kidney concentrations of HSP-70,IL-6, MPO in four groups: ischemic control (operation with cross-clamping and intraperitoneal administration of 0.9% saline, n = 7), sham (operation without cross-clamping, n = 7), heparin (ACT level about 200), and high dose heparin (ACT level up to 600). Histological analyses of the organs were performed.

Results

Histopathological evaluation of kidney presented significant differences between groups with regards to the cytoplasmic vacuole formation, hemorrhage, tubular cell degeneration and tubular dilatation while heparinized group had best results. The kidney MPO and HSP-70 levels significantly decreased (p < 0.05), but IL-6 level was not significant (p > 0.05) in heparinized group when compared to ischemic control group. No statistically significant intergroup differences were detected in the tissue samples of liver. Immunohistochemical markers of the liver were compared and no statistically significant difference was found among the groups.

Conclusion

Heparin is an important anticoagulation agent in TAAA surgical procedures but the use of higher levels of heparin in the present study revealed no beneficial effects. Bleeding complications is much less when heparin is used in the real-world clinical practice as ACT levels of 200.

Aortic aneurysm disease vs. aortic occlusive disease: differences in outcome and intensive care resource utilisation after elective surgery: an observational study

CONTEXT

Abdominal aortic surgery is a high-risk procedure, with aortic aneurysm and aortic occlusive diseases being the main indications. These groups are often regarded as having equal perioperative risk profiles. Previous reports suggest that the haemodynamic and inflammatory response to aortic clamping is more pronounced in patients with aortic aneurysm disease, which may affect outcome.

OBJECTIVES

The aim of this observational cohort study was to evaluate outcome after open elective abdominal aortic surgery, hypothesising a higher 30-day mortality, a higher incidence of postoperative organ dysfunction and a longer length of stay in patients with aortic aneurysm compared with aortic occlusive disease.

DESIGN

Cohort observational study based on prospective registrations from national databases.

SETTING

Eight Danish hospitals, including four university and four non-university centres, from 1 January 2007 to 1 March 2010.

PATIENTS

One thousand two hundred and ninety-three patients scheduled for primary open elective, aortoiliac bypass or aortofemoral bypass procedures or abdominal aortic aneurysm repair.

MAIN OUTCOME MEASURES

Mechanical ventilation, acute dialysis, use of vasopressors or inotropes, ICU stay more than 24 h, hospital length of stay and mortality.

RESULTS

Compared with aortic occlusive disease, more patients with aortic aneurysm disease had ICU stays more than 24 h (62 vs. 45%, P < 0.001) and more often needed acute dialysis or ventilatory support (17 vs. 11%, P = 0.04). No difference was found in hospital length of stay, 30-day mortality or overall risk of death. Mortality after 1 year was higher in patients with aortic aneurysm disease (8 vs. 4.7%, P = 0.04).

CONCLUSION

Patients with abdominal aortic aneurysms were at higher risk of developing postoperative organ dysfunction and required more ICU resources than patients with occlusive disease, despite no differences in hospital length of stay or 30-day mortality. Distinguishing between these two diseases may be useful in planning and distribution of ICU resources and for in future studies.

Optimising stroke volume and oxygen delivery in abdominal aortic surgery: a randomised controlled trial

BACKGROUND

Post-operative complications after open elective abdominal aortic surgery are common, and individualised goal-directed therapy may improve outcome in high-risk surgery. We hypothesised that individualised goal-directed therapy, targeting stroke volume and oxygen delivery, can reduce complications and minimise length of stay in intensive care unit and hospital following open elective abdominal aortic surgery.

METHODS

Seventy patients scheduled for open elective abdominal aortic surgery were randomised to individualised goal-directed therapy or conventional therapy. In the intervention group, stroke volume was optimised by 250 ml colloid boluses intraoperatively and for the first 6 h post-operatively. The optimisation aimed at an oxygen delivery of 600 ml/min/m(2) in the post-operative period. Haemodynamic data were collected at pre-defined time points, including baseline, intraoperatively and post-operatively. Patients were followed up for 30 days.

RESULTS

Stroke volume index and oxygen delivery index were both higher in the post-operative period in the intervention group. In this group, 27 of 32 achieved the post-operative oxygen delivery index target vs. 18 of 32 in the control group (P = 0.01). However, the number of complications per patient or length of stay in the intensive care unit or hospital did not differ between the groups.

CONCLUSION

Perioperative individualised goal-directed therapy targeting stroke volume and oxygen delivery did not affect post-operative complications, intensive care unit or hospital length of stay in open elective abdominal aortic surgery.

Endovascular aneurysm repair reverses the increased titer and the inflammatory activity of interleukin-1α in the serum of patients with abdominal aortic aneurysm

OBJECTIVE

To examine serum cytokine/chemokine profiles before and 6 months after endovascular repair (EVAR) of abdominal aortic aneurysm (AAA) and to determine whether they correlate with serum inflammatory activity using an in vitro model of leukocyte recruitment.

METHODS

Serum IL-1-α, IL-1β, IL-4, IL-6, IL-8, IL-10, IFN-γ, IP-10, MCP-1, TNF-α, and TNF-β were measured using a cytometry-based immunoassay. To test patient serum for direct inflammatory activity, human endothelial cells (EC) were stimulated with 30% patient serum for 24 hours. To test patient serum for the ability to prime EC for inflammatory responses, EC were incubated with 30% patient serum for 24 hours, followed by stimulation with low-dose (5 U/mL) TNF for 4 hours. Under both regimens of stimulation, the degree of EC activation was assessed by assaying neutrophil recruitment in a flow-based model.

RESULTS

Only IL-1α (67.9 ± 10.4 pg/mL vs 41.9 ± 7.4 pg/mL) and IL-8 (51.5 ± 5.1 vs 32.6 ± 4.7 pg/mL) changed significantly after surgery. Patient serum alone was unable to activate EC. However, serum from both time points could prime EC responses to low-dose TNF. Thus, after priming with preoperative serum, EC stimulated with TNF could recruit 76.7 ± 12.0 neutrophils/mm(2) into the subendothelial cell space. Post-EVAR serum was significantly less effective (44.4 ± 10.2 neutrophils/mm(2)). This reduction in neutrophil recruitment correlated with reduced IL-1α in post-EVAR serum. The addition of a neutralizing antibody against IL-1α to pre-EVAR serum inhibited EC priming and neutrophil recruitment, strongly implying that this cytokine was the priming agent.

CONCLUSION

EVAR reduces serum IL-1α and its inflammatory activity in patient serum. IL-1α is, therefore, implicated in the molecular pathology of AAAs and may have potential as a clinically useful biomarker.

Anesthesia for Open Abdominal Aortic Aneurysm Repair

Abdominal aortic aneurysms (AAAs) are the 13th leading cause of death in the United States 1 and approximately 40,000 patients undergo elective AAA repair each year.2 With the population aging, this number is expected to increase. Although the use of endovascular AAA repair is becoming more common, open repair, first reported by Dubost et al. in 1951 remains the gold standard.2 This chapter will review the etiology, risk factors, diagnosis, pathophysiology, operative technique, perioperative management, and postoperative complications of patients undergoing open AAA repair.

Remote ischemic preconditioning for renal protection during elective open infrarenal abdominal aortic aneurysm repair: randomized controlled trial

We aimed to determine whether remote ischemic preconditioning (IP) reduces renal damage following elective open infrarenal abdominal aortic aneurysm (AAA) repair. Sequential common iliac clamping was used to induce remote IP in randomized patients. Urinary retinol binding protein (RBP) and albumin-creatinine ratio (ACR) were measured following induction and 3, 24, and 48 hours postoperatively. In controls (n = 22), median urinary RBP increased from 112 microg/mL (interquartile range [IQR] 96-173 microg/mL) preoperatively to 5919 microg/mL (IQR 283-17 788 microg/mL) at 3 hours. Preoperative urinary RBP in preconditioned patients was 96 microg/mL (IQR 50 to 229 microg/mL) preoperatively, rising to 1243 microg/mL (IQR 540 to 15400 microg/mL) at 3 hours. Although control patients' median urinary RBP level was 5 times greater at 3 hours, there were no statistically significant differences in renal outcome indices. This trial could not confirm that remote IP reduces renal injury following elective open aneurysm surgery.