Michikazu Nakai

Activating Transcription Factor 4 Links Metabolic Stress to Interleukin-6 Expression in Macrophages

Chronic inflammation is a molecular element of the metabolic syndrome and type 2 diabetes. Saturated fatty acids (SFAs) are considered to be an important proinflammatory factor. However, it is still incompletely understood how SFAs induce proinflammatory cytokine expression. Hereby we report that activating transcription factor (ATF) 4, a transcription factor that is induced downstream of metabolic stresses including endoplasmic reticulum (ER) stress, plays critical roles in SFA-induced interleukin-6 (Il6) expression. DNA microarray analysis using primary macrophages revealed that the ATF4 pathway is activated by SFAs. Haploinsufficiency and short hairpin RNA–based knockdown of ATF4 in macrophages markedly inhibited SFA- and metabolic stress–induced Il6 expression. Conversely, pharmacological activation of the ATF4 pathway and overexpression of ATF4 resulted in enhanced Il6 expression. Moreover, ATF4 acts in synergy with the Toll-like receptor-4 signaling pathway, which is known to be activated by SFAs. At a molecular level, we found that ATF4 exerts its proinflammatory effects through at least two different mechanisms: ATF4 is involved in SFA-induced nuclear factor-κB activation; and ATF4 directly activates the Il6 promoter. These findings provide evidence suggesting that ATF4 links metabolic stress and Il6 expression in macrophages.

Haptoglobin phenotype predicts cerebral vasospasm and clinical deterioration after aneurysmal subarachnoid hemorrhage.

Vasospasm (VS) and delayed cerebral ischemia (DCI) after subarachnoid hemorrhage (SAH) are thought to greatly affect prognosis. Haptoglobin (Hp) is a hemoglobin-binding protein expressed by a genetic polymorphism (1-1, 2-1, and 2-2). Our objects were to investigate whether the Hp phenotype could predict the incidence of cerebral infarction, favorable outcome, clinical deterioration by DCI, and angiographical VS after aneurysmal SAH. Ninety-five consecutive patients who underwent clipping or coil embolization were studied. Favorable functional outcome was defined as a modified Rankin Scale score of 0-2 at 3 months. Angiographical VS was diagnosed based on cerebral angiography findings performed between days 7 and 10 after SAH. The Hp 2-2 group had a significantly greater risk of angiographical VS than that of Hp 2-1 and 1-1 groups combined on univariate (odds ratio [OR]: 3.60, confidence interval [CI]: 1.49-8.67, P = .003) and multivariate logistic regression analyses after being adjusted for age, sex, Fisher groups, and other risk factors (OR: 3.75, CI: 1.54-9.16, P = .004). The Hp 2-2 group also showed the tendency of a greater risk of clinical deterioration by DCI with marginal significance on univariate and age- and sex-adjusted analyses (univariate OR: 2.46, CI: .90-6.74, P = .080; age- and sex-adjusted OR: 2.46, CI: .89-6.82, P = .080) but not after being adjusted for other multiple risk factors. The Hp 2-2 group was not associated with the favorable 3-month outcome and cerebral infarction (univariate: P = .867, P = .209; multivariate: P = .905, P = .292). The Hp phenotype seems to be associated with a higher rate of angiographical VS and clinical deterioration by DCI but does not affect the incidence of cerebral infarction and favorable outcome.

Hypertension and lifetime risk of stroke

Background: The lifetime risk (LTR) articulates the probability of disease in the residual lifetime for an index age. These estimates can be useful for general audience-targeted knowledge translation activities against hypertension. There are only a few reports on lifetime of impact of hypertension on stroke events in Asians in whom stroke incidence is higher than Westerners. Methods: The Suita Study, a cohort study of cardiovascular diseases in Japan, was established in 1989. We included all participants who were stroke free at baseline. Age (in years) was used as the time scale. Age-specific incidence rates were calculated with person-year method within 10-year bands. We estimated the sex and index-age specific LTR of first-ever stroke with taking the competing risk of death into account. Results: We followed 5783 men and women during 1989–2007 for 74 933 person-years. During the follow-up period, 276 (149 men and 127 women) participants had incident stroke. Of them, majority were cerebral infarction; 166 (102 men and 64 women). The LTR of stroke, accounted for competing risk of death, at 45 years of age for men without hypertension was 17.21% and it was 32.79% for hypertensive men. Among the hypertensive patients, participants with stage 2 or greater hypertension had higher LTR of stroke than the participants with stage 1 hypertension. This increased LTR of stroke for hypertensive patients were also observed among women and across all index ages for stroke. Conclusion: In this urban community-based population, we observed that hypertension has significant effect on the residual LTR of stroke among both men and women of middle age, specifically for ischemic stroke.

Prognostic significance of endogenous erythropoietin in long-term outcome of patients with acute decompensated heart failure

Although previous reports suggest that an elevated endogenous erythropoietin (EPO) level is associated with worse clinical outcomes in chronic heart failure (HF) patients, the prognostic implication of EPO in patients with acute decompensated HF (ADHF) and underlying mechanisms of the high EPO level in severe HF patients who have a poor prognosis remain unclear.

High Levels of Soluble Lectin-Like Oxidized Low-Density Lipoprotein Receptor-1 in Acute Stroke: An Age- and Sex-Matched Cross-Sectional Study.

Aim: Lectin-like oxidized low-density lipoprotein receptor-1 (LOX-1) is known to be a key molecule in the pathogenesis of atherosclerosis. Although high levels of serum soluble LOX-1 (sLOX-1) were demonstrated in patients with acute coronary syndrome, there are no reports about acute stroke patients. The aim of the present study was to evaluate the levels of sLOX-1 in acute stroke patients according to different stroke subtypes. Methods: We enrolled a total of 377 patients with a stroke (men/women: 251/126; age: 40–79 years), 250 with ischemic stroke and 127 with intracerebral hemorrhage (ICH). Patients were admitted to our hospital within 3 days after the onset of stroke. As controls, we randomly selected age- and sex-matched subjects without a past history of cardiovascular disease according to stroke subtype from the community-based cohort of the Suita study. Serum LOX-1 levels were compared between stroke patients and healthy controls according to stroke subtype. Results: Median values of serum sLOX-1 in stroke patients were significantly higher than those in controls (526 vs. 486 ng/L in ischemic stroke and 720 vs. 513 ng/L in ICH, respectively). Among subtypes of ischemic stroke, median sLOX-1 levels in atherothrombotic brain infarction (641 ng/L) only were significantly higher than those in controls (496 ng/L). Ischemic stroke [odds ratio (OR), 3.80; 95% confidence interval (CI), 1.86–7.74] and ICH (OR, 5.97; 95% CI, 2.13–16.77) were independently associated with high levels of sLOX-1 by multivariate logistic regression analysis. Conclusions: Higher levels of sLOX-1 were observed in patients with acute stoke than in controls. High levels of sLOX-1 can be useful as biomarker for acute stroke.

Impact of symptom presentation on in-hospital outcomes in patients with acute myocardial infarction

BACKGROUND Limited data exist regarding the association between symptom presentation of acute myocardial infarction (AMI) and in-hospital outcomes. METHODS We analyzed data of the Japanese registry of acute Myocardial INfarction diagnosed by Universal dEfiniTion (J-MINUET). This was a prospective and multicenter registry consisting of 3085 AMI patients with available data of symptoms, who were hospitalized within 48h from onset during July 2012 to March 2014. We defined typical symptoms as any of chest pain or pressure due to myocardial ischemia. RESULTS Of this study population, 642 patients (20.8%) had atypical symptoms (atypical group) and the remaining 2443 patients (79.2%) showed typical symptoms (typical group). Compared to the typical group, the atypical group was associated with higher age, more females, hypertension, diabetes, chronic kidney disease, history of cardiovascular disease, non-ST elevation MI, and Killip class ≥2. In the atypical group, urgent percutaneous coronary intervention was less frequently performed than in the typical group, and in STEMI patients door-to-balloon time was longer in the atypical than typical group. Atypical group had larger infarct size than typical group. Furthermore, in-hospital mortality was significantly higher in atypical than in typical group (19.5% vs. 3.3%, p<0.001). In multivariable analysis, presence of atypical symptoms was an independent predictor of in-hospital mortality (odds ratio 3.12, 95% confidence interval 2.19 to 4.47, p<0.001). Moreover, the association between atypical symptoms and mortality was consistent across each subgroup. CONCLUSIONS Atypical symptoms of AMI were associated with less invasive therapy and poor outcome. Attention should be directed to these high-risk patients.

HDL cholesterol performance using an ultracentrifugation reference measurement procedure and the designated comparison method

BACKGROUND Accurate high-density lipoprotein cholesterol (HDL-C) measurements are important for management of cardiovascular diseases. The US Centers for Disease Control and Prevention (CDC) and Cholesterol Reference Method Laboratory Network (CRMLN) perform ultracentrifugation (UC) reference measurement procedure (RMP) to value assign HDL-C. Japanese CRMLN laboratory (Osaka) concurrently runs UC procedure and the designated comparison method (DCM). Osaka performance of UC and DCM was examined and compared with CDC RMP. METHODS CDC RMP involved UC, heparin-MnCl₂ precipitation, and cholesterol analysis. CRMLN DCM for samples containing <200 mg/dl triglycerides involved 50-kDa dextran sulfate-MgCl2 precipitation and cholesterol determination. RESULTS HDL-C regression equations obtained with CDC (x) and Osaka (y) were y=0.992x+0.542 (R(2)=0.996) for Osaka UC and y=1.004x-0.181 (R(2)=0.998) for DCM. Pass rates within ±1 mg/dl of the CDC target value were 91.9 and 92.1% for Osaka UC and DCM, respectively. Biases at 40 mg/dl HDL-C were +0.22 and -0.02 mg/dl for Osaka UC and DCM, respectively. CONCLUSIONS Osaka UC and DCM were highly accurate, precise, and stable for many years, assisting manufacturers to calibrate products for clinical laboratories to accurately measure HDL-C for patients, calculate non-HDL-C, and estimate low-density lipoprotein cholesterol with the Friedewald equation.

Hemodynamic determinants of mortality after Fontan operation

Background Elevated central venous pressure (CVP), low cardiac output, and mild hypoxia are common early and late after Fontan operations. However, the association of these characteristics with late mortality is unclear. We aimed to elucidate the hemodynamic determinants of mortality after Fontan operation. Method We evaluated early (group early; 0.5‐5 years postoperatively, n = 387) and late (group late; ≥15 years postoperatively, n = 161) Fontan hemodynamics that included CVP (mm Hg), cardiac index (CI; L/min per m2), systemic ventricular end‐diastolic volume index (mL/m2), ejection fraction (EF; %), and arterial blood oxygen saturation (%). We examined the effect of these variables on 5‐year all‐cause mortality. Results Mortality was higher in group late than in group early (17 vs 11, P < .0001). In both groups, higher CVP (hazard ratio [HR]1.46 and 1.38, respectively; P < .001‐.0001) and lower arterial blood oxygen saturation (HR 1.12, P < .001 for both) were associated with increased mortality. Greater end‐diastolic volume index (HR per 20: 1.73) and lower EF (HR per 10%: 3.38) were associated with increased mortality only in group early (P < .0001 for both). In contrast, only in group late was higher CI associated with increased mortality (HR 2.50, 95% CI 1.30‐4.55, P < .01). Seven patients in group late with both high CVP (≥14) and CI (≥3.0) had the highest mortality (HR 18.1, 5.55‐52.4, P < .0001). Conclusions Elevated CVP and low arterial blood oxygen saturation correlate with mortality in both early and late Fontan survivors. End‐diastolic volume index and EF are associated with mortality only in the earlier cohort, whereas interestingly, elevated cardiac output is associated with increased mortality in the later cohort.

LDL cholesterol performance of beta quantification reference measurement procedure

BACKGROUND Accurate measurement of blood lipids is crucial in cardiovascular disease risk management. The Centers for Disease Control and Prevention (CDC) Cholesterol Reference Method Laboratory Network (CRMLN) has assured the accuracy of these measurements for over 20 years using beta quantification (BQ) method as reference measurement procedure (RMP) for high- and low-density lipoprotein cholesterol (HDL-C, LDL-C). Only limited data exist about the performance of the BQ RMP. METHODS Bottom fraction cholesterol (BFC), HDL-C, and LDL-C results after ultracentrifugation from the CDC lipid reference laboratory and the Japanese CRMLN laboratory were compared using 280 serum samples measured over the past 15 years. Data were compared statistically using method comparison and bias estimation analysis. RESULTS Regression analysis between CDC (x) and Osaka (y) for BFC, HDL-C, and LDL-C were y=0.988x+1.794 (R(2)=0.997), y=0.980x+1.118 (R(2)=0.994), and y=0.987x+1.200 (R(2)=0.997), respectively. The Osaka laboratory met performance goals for 90% to 95% of the CDC reference values. CONCLUSIONS The BQ method by the Osaka CRMLN laboratory is highly accurate and has been stable for over 15 years. Accurate measurement of BFC is critical for the determination of LDL-C.

Anticoagulation combined with antiplatelet therapy in patients with left ventricular thrombus after first acute myocardial infarction

Aims There are limited data about the optimal anti-thrombotic therapy for preventing embolism while minimizing bleeding events in patients with first acute myocardial infarction (AMI) complicated by left ventricular thrombus (LVT). Methods and results Among 2301 consecutive patients with AMI hospitalized between 2001 and 2014, we studied 1850 patients with first AMI who discharged alive to investigate clinical characteristics, incidence of systemic embolism (SE), and association between anticoagulation and embolic or bleeding events. Left ventricular thrombus was diagnosed by echocardiography, left ventriculography, or cardiac magnetic resonance imaging in 92 (5.0%) patients (62 ± 12 years). During a median follow-up period of 5.4 years (interquartile range 2.1-9.1 years), SE occurred in 15 of 92 patients with LVT (16.3%) and 51 of 1758 patients without LVT (2.9%), respectively. Kaplan-Meier analysis showed a significantly higher incidence of SE in the LVT group (log-rank test, P < 0.001). Multivariate analysis showed that LVT was an independent predictor of SE. Among the LVT patients treated with vitamin K antagonists (n = 84), we compared the patients with therapeutic range (TTR) ≥50% (n = 34) and those with TTR <50% (n = 50). Only one embolic event developed in the TTR ≥50% group and nine embolic events developed in the TTR <50% group (2.9% vs. 19%, P = 0.036). There was no difference in major bleeding events (TTR ≥50%; 9% vs. TTR <50%; 8%, P = 0.89). Conclusion Appropriate anticoagulation therapy may decrease the incidence of embolic events without increasing the incidence of bleeding events in patients with first AMI complicated by LV thrombus.