Genetic Variants in P-Selectin and C-Reactive Protein Influence Susceptibility to Cognitive Decline After Cardiac Surgery

ObjectivesWe hypothesized that candidate gene polymorphisms in biologic pathways regulating inflammation, cell matrix adhesion/interaction, coagulation-thrombosis, lipid metabolism, and vascular reactivity are associated with postoperative cognitive deficit (POCD).BackgroundCognitive decline is a common complication of coronary artery bypass graft (CABG) surgery and is associated with a reduced quality of life.MethodsIn a prospective cohort study of 513 patients (86% European American) undergoing CABG surgery with cardiopulmonary bypass, a panel of 37 single-nucleotide polymorphisms (SNPs) was genotyped by mass spectrometry. Association between these SNPs and cognitive deficit at 6 weeks after surgery was tested using multiple logistic regression accounting for age, level of education, baseline cognition, and population structure. Permutation analysis was used to account for multiple testing.ResultsWe found that minor alleles of the CRP1059G/C SNP (odds ratio [OR] 0.37, 95% confidence interval [CI] 0.16 to 0.78; p = 0.013) and the SELP1087G/A SNP (OR 0.51, 95% CI 0.30 to 0.85; p = 0.011) were associated with a reduction in cognitive deficit in European Americans (n = 443). The absolute risk reduction in the observed incidence of POCD was 20.6% for carriers of the CRP1059C allele and 15.2% for carriers of the SELP1087A allele. Perioperative serum C-reactive protein (CRP) and degree of platelet activation were also significantly lower in patients with a copy of the minor alleles, providing biologic support for the observed allelic association.ConclusionsThe results suggest a contribution of P-selectin and CRP genes in modulating susceptibility to cognitive decline after cardiac surgery, with potential implications for identifying populations at risk who might benefit from targeted perioperative antiinflammatory strategies

Stimulation of α1a adrenergic receptors induces cellular proliferation or antiproliferative hypertrophy dependent solely on agonist concentration.

Stimulation of α1aAdrenergic Receptors (ARs) is known to have anti-proliferative and hypertrophic effects; however, some studies also suggests this receptor can increase cell proliferation. Surprisingly, we find the α1aAR expressed in rat-1 fibroblasts can produce either phenotype, depending exclusively on agonist concentration. Stimulation of the α1aAR by high dose phenylephrine (>10(-7) M) induces an antiproliferative, hypertrophic response accompanied by robust and extended p38 activation. Inhibition of p38 with SB203580 prevented the antiproliferative response, while inhibition of Erk or Jnk had no effect. In stark contrast, stimulation of the α1aAR with low dose phenylephrine (∼10(-8) M) induced an Erk-dependent increase in cellular proliferation. Agonist-induced Erk phosphorylation was preceded by rapid FGFR and EGFR transactivation; however, only EGFR inhibition blocked Erk activation and proliferation. The general matrix metalloprotease inhibitor, GM6001, blocked agonist induced Erk activation within seconds, strongly suggesting EGFR activation involved extracellular triple membrane pass signaling. Erk activation required little Ca(2+) release and was blocked by PLCβ or PKC inhibition but not by intracellular Ca(2+) chelation, suggesting Ca(2+) independent activation of novel PKC isoforms. In contrast, Ca(2+) release was essential for PI3K/Akt activation, which was acutely maximal at non-proliferative doses of agonist. Remarkably, our data suggests EGFR transactivation leading to Erk induced proliferation has the lowest activation threshold of any α1aAR response. The ability of α1aARs to induce proliferation are discussed in light of evidence suggesting antagonistic growth responses reflect native α1aAR function

Understanding the TXA seizure connection

Transexamic acid (TXA) is an antifibrinolytic that has been used successfully to prevent blood loss during major surgery. However, as its usage has increased, there have been growing reports of postsurgical seizure events in cardiac surgery patients. In this issue of the JCI, Lecker et al. explore this connection and suggest that TXA-mediated inhibition of glycine receptors may underlie the effect. This finding prompted the authors to explore the preclinical efficacy of common anesthetics that function by reducing the TXA-mediated inhibition to prevent or modify postsurgical seizures.National Institutes of Health (U.S.) (Grant DP1OD003646

Low dose α_1aAR stimulation activates growth-associated signaling.

<p>α_1aAR expressing cells were placed into SF media prior to pretreatment and stimulation. (<b>A</b>) Prior to counting, cells were pretreated for 30 min with vehicle (0.1% DMSO), 20 µM PD98059 (MEK/Erk inhibitor), 10 µM SB203580 (p38 inhibitor), 10 µM SP600125 (Jnk inhibitor), or 10 µM Prazosin (α₁AR) and then stimulated with 10 µM PE for 24 h. Values are the mean±SEM (n≥3); (*), P<0.05, compared to vehicle or inhibitor alone. (<b>B</b>) 20 µM PD98059 blocks PE-induced Erk phosphorylation. (<b>C</b>) Erk is acutely activated within 2 min of 10 µM PE addition and remains robustly phosphorylated for 15–30 minutes. Prior to Erk activation, stimulation induces sustained phosphorylation of EGFR and FGFR and acute transient phosphorylation of Akt at T308 downstream of PI3K/Akt signaling. Total Akt provides the load control for this multiply reprobed blot. In the lower panel, differences in temporal activation patterns are shown following semi-quantitative analysis of Erk, FGFR and Akt phosphorylation. Results represent the fold increase in phosphorylation relative to basal signal (Erk, FGFR3) or for Akt, background (arbitrary) signal.</p

Alpha1a-adrenoceptor genetic variant induces cardiomyoblast-to-fibroblast-like cell transition via distinct signaling pathways.

The role of naturally occurring human α1a-Adrenergic Receptor (α1aAR) genetic variants associated with cardiovascular disorders is poorly understood. Here, we present the novel findings that expression of human α1aAR-247R (247R) genetic variant in cardiomyoblasts leads to transition of cardiomyoblasts into a fibroblast-like phenotype, evidenced by morphology and distinct de novo expression of characteristic genes. These fibroblast-like cells exhibit constitutive, high proliferative capacity and agonist-induced hypertrophy compared with cells prior to transition. We demonstrate that constitutive, synergistic activation of EGFR, Src and ERK kinases is the potential molecular mechanism of this transition. We also demonstrate that 247R triggers two distinct EGFR transactivation-dependent signaling pathways: 1) constitutive Gq-independent β-arrestin-1/Src/MMP/EGFR/ERK-dependent hyperproliferation and 2) agonist-induced Gq- and EGFR/STAT-dependent hypertrophy. Interestingly, in cardiomyoblasts agonist-independent hyperproliferation is MMP-dependent, but in fibroblast-like cells it is MMP-independent, suggesting that expression of α1aAR genetic variant in cardiomyocytes may trigger extracellular matrix remodeling. Thus, these novel findings demonstrate that EGFR transactivation by α1aAR-247R leads to hyperproliferation, hypertrophy and alterations in cardiomyoblasts, suggesting that these unique genetically-mediated alterations in signaling pathways and cellular function may lead to myocardial fibrosis. Such extracellular matrix remodeling may contribute to the genesis of arrhythmias in certain types of heart failure

Comprehensive history of 3-year and accelerated US medical school programs: a century in review

Within the context of major medical education curricular reform ongoing in the United States, a subset of schools has re-initiated accelerated (3-year) medical education. It would be helpful for education leaders to pause and consider historical reasons such accelerated medical schools were started, and then abandoned, over the last century to proactively address important issues. As no comprehensive historical review of 3-year medical education exists, we examined all articles published on this topic since 1900. In general, US medical educational curricula began standardizing into 4-year programs in the early 1900s through contributions from William Osler, Abraham Flexner, and establishment of the American Medical Association (AMA) Council of Medical Education (CME). During WWII (1939–1945), accelerated 3-year medical school programs were initiated as a novel approach to address physician shortages; government incentives were used to boost the number of 3-year medical schools along with changed laws aiding licensure for graduates. However, this quick solution generated questions regarding physician competency, resulting in rallying cries for oversight of 3-year programs. Expansion of 3-year MD programs slowed from 1950s to 1960s until federal legislation was passed between the 1960s and the 1970s to support training healthcare workers. With renewed government financial incentives and stated desire to increase physician numbers and reduce student debt, a second rapid expansion of 3-year medical programs occurred in the 1970s. Later that decade, a second decline occurred in these programs, reportedly due to discontinuation of government funding, declining physician shortage, and dissatisfaction expressed by students and faculty. The current wave of 3-year MD programs, beginning in 2010, represents a ‘third wave’ for these programs. In this article, we identify common societal and pedagogical themes from historical experiences with accelerated medical education. These findings should provide today’s medical education leaders a historical context from which to design and optimize accelerated medical education curricula

EGFR transactivation through a TMP mechanism is required for low dose α_1aAR-induced proliferation and Erk activation.

<p>α_1aAR expressing cells were placed into SF media prior to pretreament and addition of PE. (<b>A</b>) Prior to counting, cells were pretreated for 30 min with 0.1% DMSO (Veh), 20 µM Genestein, 1 µM PD173704 (PD17), 1 µM AG1478 (AG), 1 µM PD173704+1 µM AG1478 prior to growth without (control) or with 10⁻⁸ M PE. Values are the mean±SEM; (*), P<0.05 compared to vehicle or inhibitor alone (n≥3); (**), P<0.05 compared to vehicle+PE. (<b>B</b>) Representative Western analysis of Erk phosphorylation in cells pretreated for 30 min with vehicle 0.1% DMSO (Veh), 1 µM PD17, 1 µM AG, 1 µM PD +1 µM AG or 20 µM genistein (Gen) prior to stimulation without (−) or with (+) PE at 2×10⁻⁸ M for 10 minutes. Lower panel shows semi-quantitative analysis of P-Erk band intensity from CCD images. Values are the mean±SEM (n = 4); (*), P<0.05 compared to vehicle or inhibitor alone. (<b>C</b>) Inhibition of Erk phosphorylation by a dilution series of the EGFR inhibitors, AG1478 and Erlotinib, added 5 minutes prior to stimulation with 3×10⁻⁸ M PE for 5 minutes. To maintain relative intensity, panels were concordantly adjusted. (<b>D</b>) Quantitation of P-Erk band intensity at the indicated AG1478 and Erlotinib concentrations relative to levels in untreated cells. (<b>E</b>) Top 3 panels shows western analysis of Erk phosphorylation in cells pretreated for 30 min with 0.1% DMSO (Veh) or GM6001 (GM) prior to incubation for 5 minutes without (−) or with (+) PE. The bottom panel shows a similar experiment in which the GM6001 preincubation was ∼15 seconds. Panel adjusted independently to emphasis inhibition pattern. (•) Indicates an artifactual band.</p

Stimulation of α_1aAR results in strong Ca²⁺ dependent Akt activation followed by chronic Akt downregulation at high PE concentrations.

<p>α_1aAR expressing cells were placed into SF media prior to pretreatment and stimulation with PE. Representative Western Analysis showing the PE dose dependence of (<b>A</b>) acute Akt phosphorylation from 2–10 min., (<b>B</b>) intermediate Akt and Erk phosphorylation at 1 hour and (<b>C</b>) chronic Akt dephosphorylation at 24 hours. (<b>D</b>) Treatment of cells with 0.1% DMSO vehical (−) or 20 µM BAPTA-AM (+) for 10 min. prior to 5 min stimulation with various concentration of PE demonstrate an important role for intracellular Ca²⁺ release in Akt activation that contrasts with Erk behavior.</p