Taiki Sakaguchi

Activity-Induced Protocadherin Arcadlin Regulates Dendritic Spine Number by Triggering N-Cadherin Endocytosis via TAO2β and p38 MAP Kinases

Synaptic activity induces changes in the number of dendritic spines. Here, we report a pathway of regulated endocytosis triggered by arcadlin, a protocadherin induced by electroconvulsive and other excitatory stimuli in hippocampal neurons. The homophilic binding of extracellular arcadlin domains activates TAO2beta, a splice variant of the thousand and one amino acid protein kinase 2, cloned here by virtue of its binding to the arcadlin intracellular domain. TAO2beta is a MAPKKK that activates the MEK3 MAPKK, which phosphorylates the p38 MAPK. Activation of p38 feeds-back on TAO2beta, phosphorylating a key serine required for triggering endocytosis of N-cadherin at the synapse. Arcadlin knockout increases the number of dendritic spines, and the phenotype is rescued by siRNA knockdown of N-cadherin. This pathway of regulated endocytosis of N-cadherin via protocadherin/TAO2beta/MEK3/p38 provides a molecular mechanism for transducing neuronal activity into changes in synaptic morphologies.

Quantitative Assessment of Fluid Accumulation Using Bioelectrical Impedance Analysis in Patients With Acute Decompensated Heart Failure

BACKGROUND Acute decompensated heart failure (ADHF) is generally considered to be a problem of fluid volume overload, therefore accurately quantifying the degree of fluid accumulation is of critical importance in assessing whether adequate decongestion has been achieved. The aim of this study was to develop and validate a method to quantify the degree of fluid accumulation in patients with ADHF. METHODSANDRESULTS Using multi-frequency bioelectrical impedance analysis (BIA), we measured extracellular water (ECW) volume in 130 ADHF patients on admission and at discharge. We also predicted optimal ECW volume using original equations based on data from 60 control subjects without the signs of HF. Measured/predicted (M/P) ratio of ECW in ADHF patients was observed to decrease from 1.26±0.25 to 1.04±0.17 during hospitalization (P<0.001). The amount of ECW volume reduction was significantly correlated with reduction in body weight (r=0.766, P<0.001). On multivariate analysis, higher M/P ratio of ECW at discharge was associated with increased risk of ADHF readmission or cardiac death within 6 months after discharge. CONCLUSIONS Multi-frequency BIA-measured ECW was found to offer valuable information for analyzing the pathophysiology of ADHF, and may be a useful guide in the management of this disease.

Non-Ischemic Heart Failure With Reduced Ejection Fraction Is Associated With Altered Intestinal Microbiota

BACKGROUND Research suggests that heart failure with reduced ejection fraction (HFrEF) is a state of systemic inflammation that may be triggered by microbial products passing into the bloodstream through a compromised intestinal barrier. However, whether the intestinal microbiota exhibits dysbiosis in HFrEF patients is largely unknown.Methods and Results:Twenty eight non-ischemic HFrEF patients and 19 healthy controls were assessed by 16S rRNA analysis of bacterial DNA extracted from stool samples. After processing of sequencing data, bacteria were taxonomically classified, diversity indices were used to examine microbial ecology, and relative abundances of common core genera were compared between groups. Furthermore, we predicted gene carriage for bacterial metabolic pathways and inferred microbial interaction networks on multiple taxonomic levels.Bacterial communities of both groups were dominated by the Firmicutes and Bacteroidetes phyla. The most abundant genus in both groups wasBacteroides. Although α diversity did not differ between groups, ordination by β diversity metrics revealed a separation of the groups across components of variation.StreptococcusandVeillonellawere enriched in the common core microbiota of patients, whileSMB53was depleted. Gene families in amino acid, carbohydrate, vitamin, and xenobiotic metabolism showed significant differences between groups. Interaction networks revealed a higher degree of correlations between bacteria in patients. CONCLUSIONS Non-ischemic HFrEF patients exhibited multidimensional differences in intestinal microbial communities compared with healthy subjects.

A novel scoring system to predict delirium and its relationship with the clinical course in patients with acute decompensated heart failure

BACKGROUND Delirium is known to be a poor prognostic factor in patients with acute decompensated heart failure (ADHF). The purpose of this study was to determine predictors of delirium on admission of ADHF patients, and to establish a scoring formula to identify patients at high risk for delirium. METHODS AND RESULTS We recorded the Intensive Care Delirium Screening Checklist (ICDSC) score in 120 ADHF patients during their stay in the coronary care unit (CCU). Patients with a highest ICDSC score of 4 or more were diagnosed with delirium. We examined independent candidate predictors of delirium using multivariate logistic regression analysis and developed the following scoring formula, the delirium prediction score (DPS), using independent predictors of delirium and their regression coefficients: DPS=inferior vena cava diameter+C-reactive protein (and additionally +10 for patients with a history of cerebral infarction). Receiver operating curve analysis indicated that evaluation using this scoring system at the time of admission was able to predict delirium with high accuracy (C-statistic: 0.885). In addition, the calculated scores had significantly positive correlations with duration of CCU stay and overall length of hospital stay. CONCLUSIONS We established a novel scoring system to predict on admission the likelihood of development of delirium in ADHF patients; this system also predicts prolongation of intensive care and hospital stay.

Relationship of central venous pressure to body fluid volume status and its prognostic implication in patients with acute decompensated heart failure

BACKGROUND Although central venous pressure (CVP) is a surrogate measure of preload in patients with acute decompensated heart failure (ADHF), it is a multifactorial index influenced not only by fluid volume status, but also by cardiac pump function and other factors. We aimed to elucidate the individual pathophysiological factors of CVP elevation in patients with ADHF by assessing the relationship between CVP and extracellular fluid volume status (EVS). METHODS AND RESULTS We quantified EVS in 100 patients with ADHF with the use of bioelectrical impedance analysis. CVP was also measured at the same time point. Subjects were categorized into tertiles according to their CVP-EVS ratios, and patient characteristics and clinical outcomes were compared among these tertiles. The upper-tertile group had a higher incidence of impaired right ventricular pump function, whereas the lower-tertile group had higher incidences of severe inflammation, hypoalbuminemia, and renal dysfunction. Patients in both the upper and lower tertiles had a significantly higher cardiac event rate than those in the middle tertile. CONCLUSIONS The combined assessment of CVP and EVS provides insight into both the total volume status and distribution of body fluid in ADHF patients, and it may have applications in guiding decongestive therapy and improving prognostic predictions.