[Recovery of Forgotten Memories: Modulation of Memory Recall by Brain Histamine System]

Even after memories fade they may persist latently in the brain. However, there are no clinically applicable methods for reactivating memory traces and promoting memory retrieval. In the brain histamine modulates learning and memory, sleep and wakefulness, feeding, drinking, and neuroendocrine functions. Animal studies demonstrated that histamine H₃ receptor inverse agonists enhance histamine release in the brain and promote learning and memory. In particular, the H₃ receptor inverse agonists induce recall of forgotten memories-possibly by facilitating reactivation of memory engram cells. Therefore, H₃ receptors are a promising targets for treating cognitive dysfunction. While past clinical trials failed to find beneficial effects of H₃ receptor inverse agonists on learning and memory, a recent study showed that inverse agonists enhance memory retrieval in a participant-dependent manner. This review describes the brain's histaminergic system and the modulation of learning and memory by histamine.

P824The clinical impact of polyunsaturated fatty acid on clinical outcomes in acute coronary syndrome with dyslipidemia: HIJ-PROPER sub-analysis

Background

Polyunsaturated fatty acids, especially omega-3 and -6 series, are key essential nutrients that play an important role in humans to maintain cell membranes and function. A recent randomized trial reported that adding eicosapentaenoic acid (EPA) to statins was beneficial to cardiovascular disease patients who had a residual risk factor. Further, several studies have reported that the low baseline value for EPA to arachidonic acid (AA) ratio is related to worse clinical outcome and plaque vulnerability in coronary artery disease patients. However, effects of baseline EPA/AA ratio on clinical outcomes in ACS patients have not been thoroughly evaluated.

Objectives

This study aimed to examine the impact of baseline eicosapentaenoic acid to arachidonic acid (EPA/AA) ratio on clinical outcomes of acute coronary syndrome (ACS) patients and how lipid-lowering therapy affects serum EPA/AA levels in these patients.

Methods

This is a sub-analysis of HIJ-PROPER assessing the effect of aggressive low-density lipoprotein cholesterol (LDL-C)-lowering treatment with pitavastatin+ezetimibe in 1,734 ACS patients with dyslipidemia. Patients were divided into two groups based on EPA/AA level on admission (cut-off: 0.34 μg/mL; median of baseline EPA/AA level) and clinical outcomes were examined.

Results

Percent reduction of LDL-C from baseline to follow-up and mean LDL-C level during follow-up were similar regardless of baseline EPA/AA ratio. In the low EPA/AA group, the Kaplan–Meier estimate for the primary endpoint at 3 years was 27.2% in the pitavastatin+ezetimibe group, compared with 36.6% in the pitavastatin-monotherapy group [hazard ratio (HR), 0.69; 95% confidence interval (CI), 0.52–0.93; P=0.015). However, in the high EPA/AA group, there was no significant reduction in the primary endpoint by pitavastatin+ezetimibe therapy (HR, 0.92; 95% CI, 0.70–1.20; P=0.52).

Conclusions

Aggressive lipid-lowering therapy with ezetimibe had a positive effect on clinical outcomes in the low EPA/AA group of ACS patients with dyslipidemia, but not in the high EPA/AA group. This effect was independent of LDL-C reduction and suggests that EPA/AA measurement on admission in ACS patients contributes to a “personalized” lipid-lowering approach.

P3541Change in left ventricular ejection fraction and outcome in heart failure patients with mid-range ejection fraction: from the HIJ-HF prospective study

Introduction

Heart failure (HF) is categorized on the basis of the eft ventricular ejection fraction (LVEF). The European Society of Cardiology has proposed mid-range EF (HFmrEF) as a new category of HF that includes patients with an LVEF of 40–49%. However, the clinical characteristics, change in LVEF following treatment, and outcome of patients with HFmrEF remain clear.

Methods

We conducted a prospective observational study of Japanese hospitalized HF patients between 2015 and 2018 at a single-center (HIJ-HF III). HFmrEF was defined as 40–49% of LVEF on echocardiography at admission. We followed these patients and performed echocardiography to assess LVEF per year after hospital discharge. Clinical outcome was death from any cause.

Methods and results

We studied 138 patients with HFmrEF (median age 71 years, 69% male). They had 32% of ischemic heart disease, 9% of New York Heart Association functional class III or IV at discharge. During median follow-up of 20 [13–28] months, we assessed change in LVEF for 110 patients with HFmrEF. One year after hospital discharge, 49 patients (44%) improved LVEF (≥50%) and 21 patients (19%) reduced LVEF (<40%). HFmrEF patients who reduced LVEF (<40%) were significantly higher mortality rate than those who improved LVEF (≥50%) (14% vs. 2%, p<0.05) (Figure).

Conclusions

This study demonstrated that 44% of HFmrEF patients improved LVEF following treatment but 19% patients reduced LVEF. Reduced LVEF was associated with poor prognosis.

P830Differences in the usefulness of aggressive lipid-lowering therapy among single-vessel and multi-vessel coronary artery disease patients: HIJ-PROPER sub-study

Background

Acute coronary syndrome (ACS) patients with multi-vessel disease (MVD) are at high risk of recurrent cardiovascular events. Previous study, examining stable atherosclerotic cardiac disease, reported that aggressive lipid-lowering therapy was more beneficial in MVD patients than in single-vessel disease (SVD) patients. However, no report has investigated the effects of aggressive lipid-lowering treatment according to the number of diseased coronary arteries in ACS patients.

Purpose

The purpose of the present study was to elucidate the efficacy of aggressive lipid-lowering therapy in ACS patients with MVD and SVD in modern early invasive strategy era.

Methods

The study population was derived from the HIJ-PROPER study, in which, ACS patients with dyslipidemia were randomized to pitavastatin + ezetimibe therapy (targeting LDL-C less than 70mg/dl) or pitavastatin-monotherapy (targeting LDL-C less than 90mg/dl). In the present study, the treatment efficacy was compared between patients with MVD and SVD. The primary end point was a composite of major advanced cardiovascular events (MACEs), including all-cause death, non-fatal myocardial infarction, non-fatal stroke, and ischemia driven revascularization.

Results

We identified 1702 eligible patients (mean age, 65.6 years; male, 75.6%); 869 patients (51.1%) had MVD and 833 (48.9%) patients had SVD. The rate of acute revascularization was 96.2%. The incidence of MACEs was significantly higher in MVD group compared to SVD group (43.7% vs 25.9%, hazard ratio 1.95, 95% confidence interval 1.65–2.31, p<0.001). In MVD group, there was no significant difference in MACEs between pitavastatin + ezetimibe therapy and pitavastatin-monotherapy group. (43.5% vs. 43.9%, 1.0, 0.82–1.23; p=0.95). However, in SVD group, pitavastatin + ezetimibe therapy showed significantly fewer MACEs than pitavastatin-monotherapy (34.6% vs. 47.4%, 0.72, 0.55–0.94, p=0.02). (Figure)

Conclusion

This study showed that ACS patients with SVD enjoyed significantly greater benefits from pitavastatin + ezetimibe therapy compared with pitavastatin monotherapy, whereas the patients with MVD did not. High rate of revascularization in acute phase of ACS might affect the efficacy of aggressive lipid-lowering therapy and our results in the present study suggest different treatment approach would be necessary in ACS patients with MVD in modern early invasive strategy era.

Central Histamine Boosts Perirhinal Cortex Activity and Restores Forgotten Object Memories

BACKGROUND

A method that promotes the retrieval of lost long-term memories has not been well established. Histamine in the central nervous system is implicated in learning and memory, and treatment with antihistamines impairs learning and memory. Because histamine H₃ receptor inverse agonists upregulate histamine release, the inverse agonists may enhance learning and memory. However, whether the inverse agonists promote the retrieval of forgotten long-term memory has not yet been determined.

METHODS

Here, we employed multidisciplinary methods, including mouse behavior, calcium imaging, and chemogenetic manipulation, to examine whether and how the histamine H₃ receptor inverse agonists, thioperamide and betahistine, promote the retrieval of a forgotten long-term object memory in mice. In addition, we conducted a randomized double-blind, placebo-controlled crossover trial in healthy adult participants to investigate whether betahistine treatment promotes memory retrieval in humans.

RESULTS

The treatment of H₃ receptor inverse agonists induced the recall of forgotten memories even 1 week and 1 month after training in mice. The memory recovery was mediated by the disinhibition of histamine release in the perirhinal cortex, which activated the histamine H₂ receptor. Histamine depolarized perirhinal cortex neurons, enhanced their spontaneous activity, and facilitated the reactivation of behaviorally activated neuronal ensembles. A human clinical trial revealed that treatment of H₃ receptor inverse agonists is specifically more effective for items that are more difficult to remember and subjects with poorer performance.

CONCLUSIONS

These results highlight a novel interaction between the central histamine signaling and memory engrams.

Quantitative analysis of indirect decompression in extreme lateral interbody fusion and posterior spinal fusion with a percutaneous pedicle screw system for lumbar spinal stenosis

BACKGROUND

The authors sought to quantify the results of clinical and radiological analyses of extreme lateral interbody fusion (XLIF) plus percutaneous pedicle screw (PPS) fixation for patients with lumbar spinal stenosis (LSS) by focusing on the distinct mechanism of indirect decompression.

METHODS

Data obtained from a total of 37 patients with 47 surgical sites were retrospectively analyzed. Clinical outcomes for all patients were evaluated using the Japanese Orthopaedic Association (JOA) score and the improvement rate of the JOA score. Preoperative and postoperative magnetic resonance images were used to measure the transverse areas of both the dural sac (DS area) and ligamentous flavum (LF area) in the axial sections and the length of the intervertebral disc bulge (DB length) in sagittal sections. Then, the rate of change (RC) of the DS area (RC-DS), the RC of the LF area (RC-LF), and the RC of the DB length (RC-DB) from the preoperative period to the postoperative period were calculated. Furthermore, we divided all surgical sites into the small expansion group (SE group; RC-DS <150%) and large expansion group (LE group; RC-DS ≥200%) according to the degree of RC-DS.

RESULTS

Preoperative clinical symptoms improved significantly after surgery for all patients regardless of whether the RC-DS was large or small. RC-DS, RC-LF, and RC-DB were approximately 203%, 74%, and 37%, respectively. Moreover, we found that the bulging was significantly shorter in the LE group than in the SE group, although there was no difference in the RC-LF between the LE group and SE group.

CONCLUSIONS

We suggest that indirect decompression after XLIF is particularly influenced by the degree of reduction in DB.

Prior observation of fear learning enhances subsequent self-experienced fear learning with an overlapping neuronal ensemble in the dorsal hippocampus

Information from direct experience and observation of others is integrated in the brain to enable appropriate responses to environmental stimuli. Fear memory can be acquired by observing a conspecific’s distress. However, it remains unclear how prior fear observation affects self-experienced fear learning. In this study, we tested whether prior observation of a conspecific receiving contextual fear conditioning affects subsequent self-experienced fear conditioning and how neuronal ensembles represent the integration of the observation and self-experience. Test mice observed demonstrator mice experiencing fear conditioning on day 1 and directly experienced fear conditioning on day 2. Contextual fear memory was tested on day 3. The prior observation of fear conditioning promoted subsequent self-experienced fear conditioning in a hippocampus-dependent manner. We visualized hippocampal neurons that were activated during the observation and self-experience of fear conditioning and found that self-experienced fear conditioning preferentially activated dorsal CA1 neurons that were activated during the observation. When mice observed and directly experienced fear conditioning in different contexts, preferential reactivation was not observed in the CA1, and fear memory was not enhanced. These findings indicate that dorsal CA1 neuronal ensembles that were activated during both the observation and self-experience of fear learning are implicated in the integration of observation and self-experience for strengthening fear memory.

Exposure to hot and cold environments increases noradrenaline release in the bed nucleus of the stria terminalis in rats

AIMS

Thermoregulatory responses in homeothermic animals, including humans, are classified into involuntary autonomous and voluntary behavioral thermoregulatory responses. Although behavioral thermoregulatory responses are probably driven by positive (pleasant) and/or negative (unpleasant) emotions, the neuronal mechanisms underlying the induction of negative emotions by hot and cold environments remain poorly understood. The bed nucleus of the stria terminalis is a brain region implicated in stress responses and negative emotions, such as fear, anxiety, and aversion. Various stimuli that cause negative emotions, such as immobilization stress, fox odor, gastric distension, and inflammatory pain, increase noradrenaline release in the rat bed nucleus of the stria terminalis, especially in the ventral bed nucleus of the stria terminalis. It has been reported that the negative emotional component of pain is mediated by noradrenergic neurotransmission in the ventral bed nucleus of the stria terminalis. However, the role of intra-ventral bed nucleus of the stria terminalis noradrenergic neurotransmission in the induction of negative emotion by exposure to hot and cold environments remains to be elucidated. For the first step to address this issue, the effects of hot and cold environments on noradrenaline release in the ventral bed nucleus of the stria terminalis were examined.

METHODS

In vivo microdialysis analyses in unanesthetized, freely moving male Sprague-Dawley rats were performed to examine hot and cold environments-induced noradrenaline release in the ventral bed nucleus of the stria terminalis.

RESULTS

Exposure to hot (38°C) and cold (8°C) environments significantly increased noradrenaline release in the ventral bed nucleus of the stria terminalis.

CONCLUSIONS

The results suggest that exposure to hot and cold environments enhances noradrenergic neurotransmission in the ventral bed nucleus of the stria terminalis, which may induce negative emotion, and thereby drive avoidance behaviors, that is, escape from hot and cold environments.

Short-term risk of hepatocellular carcinoma after hepatitis C virus eradication following direct-acting anti-viral treatment

BACKGROUND

With the development of direct-acting anti-virals (DAAs), almost all patients with chronic hepatitis C virus (HCV) infection can achieve sustained viral response (SVR).

AIM

To evaluate the short-term risk of HCC among patients with SVR by DAAs, including those with cirrhosis or previous HCC.

METHODS

This large-scale, multicentre cohort study included 1,675 consecutive patients who achieved SVR by treatment with interferon-free sofosbuvir-based regimens, divided into groups with (n = 152) or without previous HCC (n = 1,523). The Kaplan-Meier method and Cox proportional hazard analysis were used to calculate the cumulative HCC incidence and related factors of HCC.

RESULTS

During the follow-up period (median: 17 months), 46 (2.7%) patients developed HCC. The 1-year cumulative rates of de novo HCC were 0.4% and 4.9% for the noncirrhosis and cirrhosis groups respectively (log-rank test: P < 0.001). For cirrhotic patients, serum α-fetoprotein level at the end of treatment (EOT-AFP) was the strongest predictor of de novo HCC. The 1-year cumulative de novo HCC rates were 1.4% and 13.1% in the EOT-AFP < 9.0 ng/mL and ≥ 9.0 ng/mL groups (cut-off value) respectively (log-rank test: P < 0.001). The 1-year cumulative rates of HCC recurrence were 6.5% and 23.1% for the noncirrhosis and cirrhosis groups respectively (log-rank test: P = 0.023). For cirrhotic patients, previous HCC characteristics were significantly associated with HCC recurrence. In contrast, sex, age and metabolic features did not influence de novo HCC or recurrence.

CONCLUSIONS

For cirrhotic patients after elimination of HCV, serum EOT-AFP level and previous HCC characteristics would be useful markers for predicting de novo HCC or recurrence.

Real clinical management of patients with isolated superior mesenteric artery dissection in Japan

BACKGROUND

Due to the rarity of this condition, clinical treatment and outcomes in isolated superior mesenteric artery dissection (ISMAD) patients remain unknown. The primary aim of this retrospective multicenter study was to elucidate the treatment strategies and in-hospital outcomes for ISMAD patients by using administrative data.

METHODS

We retrospectively analyzed patients that were primarily diagnosed with ISMAD using the Diagnosis Procedure Combination data collected at 141 hospitals in Japan in 2015. Patients with comorbidities that included "aneurysm" were excluded.

RESULTS

A total of 221 ISMAD without aneurysm patients (male: 90.5%; mean age: 52.5±10.1 years) were enrolled, and 95 (67.4%) of these encountered just one ISMAD case per year. We found only one (0.5%) in-hospital death and length of stay for ISMAD patients was 13.2±9.1 days. One-third of patients received antiplatelet therapy (32.1%) and anticoagulation therapies, such as heparin (38.9%) and warfarin (10.0%). A total of 146 (66.1%) patients received antihypertensive treatment (either orally or via an intravenous route) during hospitalization. Twelve (5.4%) patients underwent surgical procedures during hospitalization as follows: 4 (33.3%) patients underwent bypass surgery, 3 (25.0%) patients underwent exploratory laparotomies, 2 (16.7%) patients underwent bowel resection, 1 (8.3%) patient underwent a thrombectomy, and 2 (16.7%) patients underwent surgical angioplasties.

CONCLUSIONS

We found that conservative therapy for ISMAD patients without aneurysm is safe and is also associated with a low rate of surgical intervention in clinical practice.