Preoperative gene expression may be associated with neurocognitive decline after cardiopulmonary bypass

Effect of Patient Sex on Neurocognitive Decline after Cardiac Surgery

BACKGROUND

Neurocognitive decline (NCD) is a common complication of cardiac surgery. Understanding risk factors helps surgeons counsel patients pre- and perioperatively about risk, prevention, and treatment.

STUDY DESIGN

Patients undergoing cardiac surgery using cardiopulmonary bypass underwent pre- and postoperative neurocognitive testing. Neurocognitive data are presented as a change from baseline to either postoperative day 4 or to 1 month. The score is standardized with respect to age.

RESULTS

Eighty-four patients underwent surgery and completed postoperative neurocognitive testing. There was no significant difference in baseline neurocognitive function. NCD was more common in female patients (71%) than male patients (26.4%) on postoperative day 4. By 1 month, the incidence of NCD is similar between female (15.0%) and male patients (14.3%). Of note, female patients differed from male patients in preoperative hematocrit, preoperative creatinine, and type of surgery.

CONCLUSIONS

In the acute postoperative period, female patients are both more likely to experience NCD and experience a more severe change from baseline cognitive function. This difference between male and female patients resolves by the 1 month follow-up point. Female patients had a lower preoperative hematocrit and were more likely to receive intraoperative and perioperative blood transfusion. Lower preoperative hematocrit appears to mediate the difference in NCD between male and female patients.

Network Biology Approaches to Uncover Therapeutic Targets Associated with Molecular Signaling Pathways from circRNA in Postoperative Cognitive Dysfunction Pathogenesis

Postoperative cognitive dysfunction (POCD) is a cognitive deterioration and dementia that arise after a surgical procedure, affecting up to 40% of surgery patients over the age of 60. The precise etiology and molecular mechanisms underlying POCD remain uncovered. These reasons led us to employ integrative bioinformatics and machine learning methodologies to identify several biological signaling pathways involved and molecular signatures to better understand the pathophysiology of POCD. A total of 223 differentially expressed genes (DEGs) comprising 156 upregulated and 67 downregulated genes were identified from the circRNA microarray dataset by comparing POCD and non-POCD samples. Gene ontology (GO) analyses of DEGs were significantly involved in neurogenesis, autophagy regulation, translation in the postsynapse, modulating synaptic transmission, regulation of the cellular catabolic process, macromolecule modification, and chromatin remodeling. Pathway enrichment analysis indicated some key molecular pathways, including mTOR signaling pathway, AKT phosphorylation of cytosolic targets, MAPK and NF-κB signaling pathway, PI3K/AKT signaling pathway, nitric oxide signaling pathway, chaperones that modulate interferon signaling pathway, apoptosis signaling pathway, VEGF signaling pathway, cellular senescence, RANKL/RARK signaling pathway, and AGE/RAGE pathway. Furthermore, seven hub genes were identified from the PPI network and also determined transcription factors and protein kinases. Finally, we identified a new predictive drug for the treatment of SCZ using the LINCS L1000, GCP, and P100 databases. Together, our results bring a new era of the pathogenesis of a deeper understanding of POCD, identified novel therapeutic targets, and predicted drug inhibitors in POCD.

Glycemic control is not associated with neurocognitive decline after cardiac surgery

BACKGROUND

Whether perioperative glycemic control is associated with neurocognitive decline (NCD) after cardiac surgery was examined.

METHODS

Thirty patients undergoing cardiac surgery utilizing cardiopulmonary bypass (CPB) were screened for NCD preoperatively and on postoperative day 4 (POD4). Indices of glucose control were examined. Serum cytokine levels were measured and human transcriptome analysis was performed on blood samples. Neurocognitive data are presented as a change from baseline to POD4 in a score standardized with respect to age and gender.

RESULTS

A decline in neurocognitive function was identified in 73% (22/30) of patients on POD4. There was no difference in neurocognitive function between patients with elevated HbA1c levels preoperatively (p = .973) or elevated fasting blood glucose levels the morning of surgery (>126 mg/dl, p = .910), or a higher maximum blood glucose levels during CPB (>180 mg/dl, p = .252), or higher average glucose levels during CPB (>160 mg/dl, p = .639). Patients with postoperative leukocytosis (WBC ≥ 10.5) had more NCD when compared to their baseline function (p = .03). Patients with elevated IL-8 levels at 6 h postoperatively had a significant decline in NCD at POD4 (p = .04). Human transcriptome analysis demonstrated unique and differential patterns of gene expression in patients depending on the presence of DM and NCD.

CONCLUSIONS

Perioperative glycemic control does not have an effect on NCD soon after cardiac surgery. The profile of gene expression was altered in patients with NCD with or without diabetes.

Smelling the Dark Proteome: Functional Characterization of PITH Domain-Containing Protein 1 (C1orf128) in Olfactory Metabolism

The Human Proteome Project (HPP) consortium aims to functionally characterize the dark proteome. On the basis of the relevance of olfaction in early neurodegeneration, we have analyzed the dark proteome using data mining in public resources and omics data sets derived from the human olfactory system. Multiple dark proteins localize at synaptic terminals and may be involved in amyloidopathies such as Alzheimer's disease (AD). We have characterized the dark PITH domain-containing protein 1 (PITHD1) in olfactory metabolism using bioinformatics, proteomics, in vitro and in vivo studies, and neuropathology. PITHD1^-/- mice exhibit olfactory bulb (OB) proteome changes related to synaptic transmission, cognition, and memory. OB PITHD1 expression increases with age in wild-type (WT) mice and decreases in Tg2576 AD mice at late stages. The analysis across 6 neurological disorders reveals that olfactory tract (OT) PITHD1 is specifically upregulated in human AD. Stimulation of olfactory neuroepithelial (ON) cells with PITHD1 alters the ON phosphoproteome, modifies the proliferation rate, and induces a pro-inflammatory phenotype. This workflow applied by the Spanish C-HPP and Human Brain Proteome Project (HBPP) teams across the ON-OB-OT axis can be adapted as a guidance to decipher functional features of dark proteins. Data are available via ProteomeXchange with identifiers PXD018784 and PXD021634.

Lower preoperative hematocrit, longer hospital stay, and neurocognitive decline after cardiac surgery

BACKGROUND

Cardiopulmonary bypass may be associated with postoperative neurocognitive dysfunction; however, risk factors have not been clearly identified. We hypothesize that lower hematocrit levels are correlated with postoperative neurocognitive dysfunction.

METHODS

A total of 30 patients underwent cardiac operations utilizing cardiopulmonary bypass and screening for neurocognitive dysfunction preoperatively and on postoperative day 4. Patients were analyzed according to hematocrit preoperatively, 6 hours postoperatively, and on postoperative day 4, and whether they received intra or postoperative transfusions of packed red blood cells. Neurocognitive data is presented as a difference in Repeatable Battery for the Assessment of Neuropsychological Status standardized score from baseline to postoperative day 4 and analyzed by unpaired two-tailed Spearman test and unpaired Mann-Whitney U test.

RESULTS

There was a significant correlation between patients with lower hematocrit before surgery and a decline in neurocognitive function at postoperative day 4 (P < .05). All patients experienced a decrease in hematocrit during their hospital stay, but the hematocrit 6 hours postoperatively and postoperative day 4 did not impact cognition. Receiving a transfusion was also not associated with neurocognitive dysfunction. Patients with low hematocrit preoperatively had a consistently lower hematocrit throughout their stay. Prolonged total length of stay was also significantly associated with neurocognitive decline.

CONCLUSION

A lower preoperative hematocrit and prolonged length of hospital stay are correlated with neurocognitive decline after cardiac surgery utilizing cardiopulmonary bypass.

Intravenous Amiodarone and Sotalol Impair Contractility and Cardiac Output, but Procainamide Does Not: A Langendorff Study

INTRODUCTION

Direct comparison of the effects of antiarrhythmic agents on myocardial performance may be useful in choosing between medications in critically ill patients. Studies directly comparing multiple antiarrhythmic medications are lacking. The use of an experimental heart preparation permits examination of myocardial performance under constant loading conditions.

METHODS

Hearts of Sprague Dawley rats (n = 35, 402-507 g) were explanted and cannulated in working heart model with fixed preload and afterload. Each heart was then exposed to a 3-hour infusion of procainamide (20 µg/kg/min), esmolol (100 or 200 µg/kg/min), amiodarone (10 or 20 mg/kg/d), sotalol (80 mg/m²/d), or placebo infusions (n = 5 per dose). Cardiac output, contractility (dP/dT_max), diastolic performance (dP/dT_min), and heart rate were compared between groups over time by linear mixed modeling.

RESULTS

Compared with placebo, sotalol decreased contractility by an average of 24% ( P < .001) over the infusion period, as did amiodarone (low dose by 13%, P = .029; high dose by 14%, P = .013). Compared with placebo, mean cardiac output was significantly lower in animals treated with sotalol (by 22%, P = .016) and esmolol 200 μg/kg/min (by 23%, P = .012). Over time, amiodarone decreased cardiac output (20 mg/kg/d, β = -89 [-144, -33] μL/min² decrease, P = .002) and also worsened diastolic function, decreasing dP/dT_min by ∼18% and 22% ( P = .032 and P = .011, low and high doses, respectively). Procainamide did not have a significant effect on any measures of systolic or diastolic performance.

CONCLUSIONS

In isolated hearts, amiodarone and sotalol depressed myocardial contractility, cardiac output, and diastolic function. However, procainamide did not negatively affect myocardial performance and represents a favorable agent in settings of therapeutic equivalence.

Enhanced coronary arteriolar contraction to vasopressin in patients with diabetes after cardiac surgery

OBJECTIVE

Cardioplegic arrest (CP) and cardiopulmonary bypass (CPB) are associated with vasomotor dysfunction of coronary arterioles in patients with diabetes (DM) undergoing cardiac surgery. We hypothesized that DM may up-regulate vasopressin receptor expression and alter the contractile response of coronary arterioles to vasopressin in the setting of CP/CPB.

METHODS

Right atrial tissue samples of patients with DM and without (ND) (n = 8 in each group) undergoing cardiac surgery were harvested before and after CP/CPB. The isolated coronary arterioles (80-150 μm) dissected from the harvested right atrial tissue samples were cannulated and pressurized (40 mm Hg) in a no-flow state. The changes in diameter were measured with video microscopy. The protein expression/localization of vasopressin 1A receptors (V1A) and vasopressin 1B receptors (V1B) in the atrial tissue were measured by immune-blotting and immunohistochemistry.

RESULTS

The pre-CP/CPB contractile responses of the coronary arterioles to vasopressin were significantly increased post-CP/CPB in both the ND and DM groups. This effect was more pronounced in the vessels from patients in the DM group than that of vessels from patients in the ND group (P < .05). Vasopressin-induced contractile response of the coronary arterioles was inhibited in the presence of the specific V1A antagonist SR 49059 (10-7 M) in both ND and DM vessels (P < .05). The post-CP/CPB protein levels of V1A were significantly increased compared with pre-CP/CPB values in both the ND and DM groups (P < .05), whereas this increase was greater in DM than that of ND (P < .05). Immunohistochemistry staining further indicates that V1B were mainly expressed in the myocardium but not in vascular smooth muscle.

CONCLUSIONS

CP/CPB and DM are both associated with up-regulation in V1 receptor expression/localization in human myocardium. Vasopressin may induce coronary arteriolar constriction via V1A. This alteration may lead to increased coronary arteriolar spasm in patients with DM undergoing CP/CPB and cardiac surgery.

Atrial Fibrillation, Neurocognitive Decline and Gene Expression After Cardiopulmonary Bypass

OBJECTIVE

Atrial fibrillation and neurocognitive decline are common complications after cardiopulmonary bypass. By utilizing genomic microarrays we investigate whether gene expression is associated with postoperative atrial fibrillation and neurocognitive decline.

METHODS

Twenty one cardiac surgery patients were prospectively matched and underwent neurocognitive assessments pre-operatively and four days postoperatively. The whole blood collected in the pre-cardiopulmonary bypass, 6 hours after-cardiopulmonary bypass, and on the 4^th postoperative day was hybridized to Affymetrix Gene Chip U133 Plus 2.0 Microarrays. Gene expression in patients who developed postoperative atrial fibrillation and neurocognitive decline (n=6; POAF+NCD) was compared with gene expression in patients with postoperative atrial fibrillation and normal cognitive function (n=5; POAF+NORM) and patients with sinus rhythm and normal cognitive function (n=10; SR+NORM). Regulated genes were identified using JMP Genomics 4.0 with a false discovery rate of 0.05 and fold change of >1.5 or <-1.5.

RESULTS

Eleven patients developed postoperative atrial fibrillation. Six of these also developed neurocognitive decline. Of the 12 patients with sinus rhythm, only 2 developed neurocognitive decline. POAF+NCD patients had unique regulation of 17 named genes preoperatively, 60 named genes six hours after cardiopulmonary bypass, and 34 named genes four days postoperatively (P<0.05) compared with normal patients. Pathway analysis demonstrated that these genes are involved in cell death, inflammation, cardiac remodeling and nervous system function.

CONCLUSION

Patients who developed postoperative atrial fibrillation and neurocognitive decline after cardiopulmonary bypass may have differential genomic responses compared to normal patients and patients with only postoperative atrial fibrillation, suggesting common pathophysiology for these conditions. Further exploration of these genes may provide insight into the etiology and improvements of these morbid outcomes.