Mindfulness intervention improves cognitive function in older adults by enhancing the level of miRNA-29c in neuron-derived extracellular vesicles.

Although mindfulness-based stress reduction (MBSR) improves cognitive function, the mechanism is not clear. In this study, people aged 65 years and older were recruited from elderly communities in Chitose City, Japan, and assigned to a non-MBSR group or a MBSR group. Before and after the intervention, the Japanese version of the Montreal Cognitive Assessment (MoCA-J) was administered, and blood samples were collected. Then, neuron-derived extracellular vesicles (NDEVs) were isolated from blood samples, and microRNAs, as well as the target mRNAs, were evaluated in NDEVs. A linear mixed model analysis showed significant effects of the MBSR x time interaction on the MoCA-J scores, the expression of miRNA(miR)-29c, DNA methyltransferase 3 alpha (DNMT3A), and DNMT3B in NDEVs. These results indicate that MBSR can improve cognitive function by increasing the expression of miR-29c and decreasing the expression of DNMT3A, as well as DNMT3B, in neurons. It was also found that intracerebroventricular injection of miR-29c mimic into 5xFAD mice prevented cognitive decline, as well as neuronal loss in the subiculum area, by down-regulating Dnmt3a  and Dnmt3b  in the hippocampus. The present study suggests that MBSR can prevent neuronal loss and cognitive impairment by increasing the neuronal expression of miR-29c.

Perioperative Serum Free Hemoglobin and Haptoglobin Levels in Valvular and Aortic Surgery With Cardiopulmonary Bypass: Their Associations With Postoperative Kidney Injury.

OBJECTIVE: To observe the perioperative free hemoglobin and haptoglobin levels and to assess their associations with the risk of postoperative acute kidney injury (pAKI) in adult patients undergoing valvular and aortic surgery requiring cardiopulmonary bypass (CPB). DESIGN: A single-center, prospective, observational study. SETTING: Public teaching hospital. PARTICIPANTS: The study comprised 74 adult patients without chronic renal failure who underwent cardiovascular surgery requiring CPB from 2014 to 2020. MEASUREMENTS AND MAIN RESULTS: Perioperative free hemoglobin and haptoglobin levels during the study period were obtained from study participants. The primary outcome was pAKI defined by the Kidney Disease: Improving Global Outcomes criteria. Of the 74 patients in this study, pAKI occurred in 25 patients (33.8%). The free hemoglobin level began to increase after the initiation of CPB and reached a peak level at 30 minutes after weaning from CPB. It returned to the baseline level on postoperative day one. Haptoglobin levels were the highest after anesthesia induction and decreased continuously until postoperative day one. In the multivariate analysis, maximum free hemoglobin and minimum haptoglobin were associated independently with increased risk of pAKI (adjusted odds ratio 1.33 [95% confidence interval 1.12-1.58; p = 0.001] and 0.95 [95% confidence interval 0.91-1.00; p = 0.03], respectively). The free hemoglobin level began to have an independent association with pAKI at one hour after commencement of CPB, and the independent association disappeared at postoperative day one. CONCLUSIONS: This study found that the perioperative increase of the free hemoglobin level and the decrease of the haptoglobin level had independent associations with the risk of pAKI.

Bone marrow-derived mesenchymal stem cells improve cognitive impairment in an Alzheimer's disease model by increasing the expression of microRNA-146a in hippocampus.

Alzheimer's disease (AD) is characterized by the accumulation of amyloid-ß and tau. We previously reported that administration of bone marrow mesenchymal stem cells (BM-MSCs) ameliorates diabetes-induced cognitive impairment by transferring exosomes derived from these cells into astrocytes. Here, we show that intracerebroventricularly injected BM-MSCs improve cognitive impairment in AD model mice by ameliorating astrocytic inflammation as well as synaptogenesis. Although AD model mice showed an increase in NF-κB in the hippocampus, BM-MSC-treated AD model mice did not show this increase but showed an increase in levels of microRNA (miR)-146a in the hippocampus. Intracerebroventricularly injected BM-MSCs were attached to the choroid plexus in the lateral ventricle, and thus, BM-MSCs may secrete exosomes into the cerebrospinal fluid. In vitro experiments showed that exosomal miR-146a secreted from BM-MSCs was taken up into astrocytes, and an increased level of miR-146a and a decreased level of NF-κB were observed in astrocytes. Astrocytes are key cells for the formation of synapses, and thus, restoration of astrocytic function may have led to synaptogenesis and correction of cognitive impairment. The present study indicates that exosomal transfer of miR-146a is involved in the correction of cognitive impairment in AD model mice.

An enriched environment prevents cognitive impairment in an Alzheimer's disease model by enhancing the secretion of exosomal microRNA-146a from the choroid plexus.

Alzheimer's disease (AD) is characterized by the extensive deposition of amyloid-ß plaques and neurofibrillary tangles. We previously found that preserved function of astrocytes is associated with cognitively normal subjects with AD pathology. Here we show that an enriched environment (EE) can prevent cognitive impairment in AD model mice by ameliorating astrocytic inflammation and increasing synaptic density in the subiculum area of the hippocampus. In AD model mice treated with an EE, increased levels of microRNA (miR)-146a and down-regulation of NF-κB were observed in the hippocampus. In addition, increased levels of interferon (IFN)-γ were seen in serum from mice exposed to an EE. In vitro, enhanced miR-146a expression was observed in exosomes derived from the choroid plexus (CP) after IFN-γ treatment. In further in vitro experiments, we transfected miR-146a into Aß/lipopolysaccharide-induced inflammatory astrocytes and showed that miR-146a ameliorated astrocytic inflammation by down-regulating tumor necrosis factor receptor-associated factor 6 and NF-κB. The present study indicates that following an EE, exosomal miR-146a derived from the CP cells is a key factor in ameliorating astrocytic inflammation, leading to synaptogenesis and correction of cognitive impairment.

An enriched environment prevents diabetes-induced cognitive impairment in rats by enhancing exosomal miR-146a secretion from endogenous bone marrow-derived mesenchymal stem cells.

Increasing evidence suggests that an enriched environment (EE) ameliorates cognitive impairment by promoting repair of brain damage. However, the mechanisms by which this occurs have not been determined. To address this issue, we investigated whether an EE enhanced the capability of endogenous bone marrow-derived mesenchymal stem/stromal cells (BM-MSCs) to prevent hippocampal damage due to diabetes by focusing on miRNA carried in BM-MSC-derived exosomes. In diabetic streptozotocin (STZ) rats housed in an EE (STZ/EE), cognitive impairment was significantly reduced, and both neuronal and astroglial damage in the hippocampus was alleviated compared with STZ rats housed in conventional cages (STZ/CC). BM-MSCs isolated from STZ/CC rats had functional and morphological abnormalities that were not detected in STZ/EE BM-MSCs. The miR-146a levels in exosomes in conditioned medium of cultured BM-MSCs and serum from STZ/CC rats were decreased compared with non-diabetic rats, and the level was restored in STZ/EE rats. Thus, the data suggest that increased levels of miR-146a in sera were derived from endogenous BM-MSCs in STZ/EE rats. To examine the possibility that increased miR-146a in serum may exert anti-inflammatory effects on astrocytes in diabetic rats, astrocytes transfected with miR-146a were stimulated with advanced glycation end products (AGEs) to mimic diabetic conditions. The expression of IRAK1, NF-κB, and tumor necrosis factor-α was significantly higher in AGE-stimulated astrocytes, and these factors were decreased in miR-146a-transfected astrocytes. These results suggested that EEs stimulate up-regulation of exosomal miR-146a secretion by endogenous BM-MSCs, which exerts anti-inflammatory effects on damaged astrocytes and prevents diabetes-induced cognitive impairment.

Inhibition of glycogen synthase kinase-3 reduces extension of the axonal leading process by destabilizing microtubules in cerebellar granule neurons.

Recent studies have uncovered various molecules that play key roles in neuronal morphogenesis. Nevertheless, the mechanisms underlying the neuron-type-dependent regulation of morphogenesis remain unknown. We have previously reported that inhibition of glycogen synthase kinase-3 (GSK3) markedly reduced axonal length of cerebellar granule neurons (CGNs) in a neuron-type-dependent manner. In the present study, we investigated the mechanisms by which the growth of CGN axons was severely suppressed upon GSK3 inhibition. Using time-lapse imaging of cultured CGNs at early morphogenesis, we found that extension of the leading process was severely inhibited by the pharmacological inhibition of GSK3. The rate of somal migration was also reduced with a GSK3 inhibitor in dissociated culture as well as in microexplant culture. In addition, CGNs ectopically expressed with a catalytically inactive mutant of GSK3 exhibited a migration defect in vivo. In axonal leading processes of CGNs, detyrosination and acetylation of α-tubulin, which are known to correlate with microtubule stability, were decreased by GSK3 inhibition. A photoconversion analysis found that inhibition of GSK3 increases the turnover of microtubules. Furthermore, in the presence of paclitaxel, a microtubule-stabilizing reagent, inhibition of GSK3 recovered the axonal leading process extension that was reduced by paclitaxel. Our results suggest that GSK3 supports the extension of axonal processes by stabilizing microtubules, contrary to its function in other neuron-types, lending mechanical insight into neuron-type-dependent morphological regulation.

Association of direct bilirubin level with postoperative outcome in critically ill postoperative patients.

BACKGROUND: Hyperbilirubinemia is a common postoperative complication. Elevated direct bilirubin (D-Bil) and indirect bilirubin (I-Bil) levels are related to different pathophysiologies; therefore, their associations with outcomes also differ. However, there have been few comparative studies of such associations in postoperative patients. METHODS: This retrospective study compared the associations of postoperative D-Bil and I-Bil with outcomes. We included adult patients requiring postoperative intensive care for more than 48 hours between 2008 and 2013, except those undergoing liver operations. The number of patients was determined using a power calculation. D-Bil and I-Bil measurements were obtained on postoperative days (POD) 1 and 2. The primary outcome was defined as hospital mortality, with the number of ICU-free survival days (IFSD) at POD 28 as the secondary outcome. RESULTS: The study population consisted of 1,903 patients with a mortality rate of 2.2%. D-Bil at POD 1 was significantly higher in non-survivors than survivors (P = 0.001), but I-Bil at POD 1 showed no such relation (P = 0.209). Multivariate logistic analysis indicated that higher postoperative D-Bil was independently associated with increased postoperative mortality (POD 1: adjusted odds ratio [OR] = 2.32, P < 0.001; POD 2: adjusted OR = 1.95, P < 0.001), but I-Bil showed no such relation (POD 1: P = 0.913; POD 2: P = 0.209). Increased D-Bil was independently associated with decreased IFSD at POD 28 (POD 1: adjusted coefficient = -1.54, P < 0.001; POD 2: -1.84, P < 0.001). In contrast, increased I-Bil at POD 1 was independently associated with increased IFSD at POD 28 (POD 1: adjusted coefficient = +0.39, P = 0.021; POD 2: +0.33, P = 0.080). CONCLUSIONS: D-Bil indices have a higher capability than I-Bil for predicting poorer outcomes in critically ill postoperative patients.

Activated forms of astrocytes with higher GLT-1 expression are associated with cognitive normal subjects with Alzheimer pathology in human brain.

Although the cognitive impairment in Alzheimer's disease (AD) is believed to be caused by amyloid-ß (Aß) plaques and neurofibrillary tangles (NFTs), several postmortem studies have reported cognitive normal subjects with AD brain pathology. As the mechanism underlying these discrepancies has not been clarified, we focused the neuroprotective role of astrocytes. After examining 47 donated brains, we classified brains into 3 groups, no AD pathology with no dementia (N-N), AD pathology with no dementia (AD-N), and AD pathology with dementia (AD-D), which represented 41%, 21%, and 38% of brains, respectively. No differences were found in the accumulation of Aß plaques or NFTs in the entorhinal cortex (EC) between AD-N and AD-D. Number of neurons and synaptic density were increased in AD-N compared to those in AD-D. The astrocytes in AD-N possessed longer or thicker processes, while those in AD-D possessed shorter or thinner processes in layer I/II of the EC. Astrocytes in all layers of the EC in AD-N showed enhanced GLT-1 expression in comparison to those in AD-D. Therefore these activated forms of astrocytes with increased GLT-1 expression may exert beneficial roles in preserving cognitive function, even in the presence of Aß and NFTs.

Haptoglobin Administration in Cardiovascular Surgery Patients: Its Association With the Risk of Postoperative Acute Kidney Injury.

BACKGROUND: Acute kidney injury (AKI) often occurs after cardiac surgery. During cardiac surgery, plasma free hemoglobin (fHb) would increase due to hemolysis. Since plasma fHb is thought to be nephrotoxic, haptoglobin, which is an fHb scavenger, may have the potential to prevent postoperative AKI (pAKI). However, there have been few studies in which the association of intraoperative administration of haptoglobin with the incidence of AKI after cardiac surgery was assessed. METHODS: This study was a retrospective observational study to assess the independent association of intraoperative administration of haptoglobin with the incidence pAKI in cardiac surgery patients. We screened cardiac surgery patients who required cardiopulmonary bypass from 2008 to 2015. We excluded patients who required renal replacement therapy preoperatively. We also excluded patients in whom descending aortic replacement was performed. pAKI was defined according to AKI Network criteria. A propensity score-matched model was used to adjust confounders. For sensitive analysis, we further developed a logistic regression model. RESULTS: We included 1326 patients in this study. The incidence of AKI in the total cohort was 25.5% (338 patients). Haptoglobin was administered in 260 patients (19.6%). In the crude cohort, the incidence of AKI in patients with haptoglobin administration was 24.6%, which was not significantly different from the incidence of 25.7% in those without haptoglobin administration (P = .72; odds ratio, 0.94 [95% confidence interval, 0.69-1.29]). After propensity score matching, we had 249 patients in each group (for a total of 498 patients). In this propensity score-matched cohort, the incidence of AKI in patients with haptoglobin administration was 22.5%, which was significantly lower than the incidence of 30.9% in those without haptoglobin administration (P = .033; odds ratio, 0.65 [0.43-0.97]). In our logistic regression model for the risk of pAKI, haptoglobin administration was independently associated with decreased risk of AKI (P = .029; adjusted odds ratio, 0.54 [0.31, 0.93]). CONCLUSIONS: In this hypothesis-generating, single-center retrospective observational study, intraoperative administration of haptoglobin was independently associated with lower risk of AKI after cardiovascular surgery.

Association between Intra-Circuit Activated Clotting Time and Incidence of Bleeding Complications during Continuous Renal Replacement Therapy using Nafamostat Mesilate: a Retrospective Pilot Observational Study.

It has been proposed that anticoagulant activity during continuous renal replacement therapy with nafamostat mesilate can be monitored by using intra-circuit activated clotting time. However, it is still unclear whether activated clotting time would be useful for this purpose. We conducted a retrospective study and included 76 patients who required continuous renal replacement therapy using nafamostat mesilate. We obtained information for pre- and post-filter activated clotting times and bleeding complications. We calculated time-weighted average activated clotting time. We divided the patients into three activated clotting time groups (low, middle, high) according to the tertiles of pre- and post-filter activated clotting times. Regarding post-filter time-weighted average activated clotting time, the incidence of bleeding complications in the high activated clotting time group was significantly higher than those in the low and middle activated clotting time groups (p=0.04). The incidences of bleeding complications were not significantly different among the three groups according to pre-filter time-weighted average activated clotting time (p=0.35). In sensitive analysis, the duration on continuous renal replacement therapy without bleeding complications was significantly longer for filters with post-tw ACT<262 than for those with post-tw ACT≥262 (p=0.03). This result suggested that post-filter time-weighted average activated clotting time might be a good predictor of bleeding complications during continuous renal replacement therapy with nafamostat mesilate. Further study is required to refute or confirm our findings.

Comparison of nafamostat mesilate and unfractionated heparin as anticoagulants during continuous renal replacement therapy.

PURPOSE: Nafamostat mesilate (NM) can be used as a regional anticoagulant for continuous renal replacement therapy (CRRT). The primary aim of this study was to assess the association of the use of NM with risk of bleeding complications and compare it with the use of unfractionated heparin (UFH). METHODS: We conducted a single-center retrospective observational study. We included adult patients who required CRRT in our intensive care unit from 2011 to 2013. The primary outcome was the risk of bleeding complications during CRRT and the secondary outcome was filter life for the first filter of CRRT. RESULTS: We included 101 patients (76 with NM, 25 with UFH). Among the 101 patients, use of NM tended to be associated with lower risk of bleeding complications (6.6% vs. 16%; odds ratio, 0.37; p = 0.16). Propensity score matching generated 30 patients with NM and 15 patients with UFH with well-balanced baseline characteristics. Among the propensity score-matched cohorts, use of NM was significantly associated with decreased risk of bleeding complications (3.3% vs. 27%; odds ratio, 0.09; p = 0.04). In multivariate logistic analysis using the inverse probability of treatment weighting for sensitive analysis, the use of NM was independently associated with reduced risk of bleeding complications (p = 0.02). The median filter life was not significantly different for patients with NM and patients with UFH (25.5 hours vs. 30.5 hours, p = 0.16). CONCLUSIONS: In our retrospective analysis, the use of NM as an anticoagulant during CRRT was associated with decreased incidence of bleeding complications compared with the use of UFH.

A low-density culture method of cerebellar granule neurons with paracrine support applicable for the study of neuronal morphogenesis.

Cerebellar granule neuronal cultures have been used to study the molecular mechanisms underlying neuronal functions, including neuronal morphogenesis. However, a limitation of this system is the difficulty to analyze isolated neurons because these are required to be maintained at a high density. Therefore, in the present study, we aimed to develop a simple and cost-effective method for culturing low-density cerebellar granule neurons. Cerebellar granule cells at two different densities (low- and high-density) were co-cultivated in order for the low-density culture to be supported by the paracrine signals from the high-density culture. This method enabled morphology analysis of isolated cerebellar granule neurons without astrocytic feeder cultures or supplements such as B27. Using this method, we investigated the function of a polarity factor. Studies using hippocampal neurons suggested that glycogen synthase kinase-3 (GSK-3) is an essential regulator of neuronal polarity, and inhibition of GSK-3 results in the formation of multiple axons. Pharmacological inhibitors for GSK-3 (6-bromoindirubin-3'-oxime and lithium chloride) did not cause the formation of multiple axons of cerebellar granule neurons but significantly reduced their length. Consistent results were obtained by introducing kinase-dead form of GSK-3 beta (K85A). These results indicated that GSK-3 is not directly involved in the control of neuronal polarity in cerebellar granule neurons. Overall, this study provides a simple method for culturing low-density cerebellar granule neurons and insights in to the neuronal-type dependent function of GSK-3 in neuronal morphogenesis.