Ryuta Morihara

Strong Impact of Chronic Cerebral Hypoperfusion on Neurovascular Unit, Cerebrovascular Remodeling, and Neurovascular Trophic Coupling in Alzheimer's Disease Model Mouse.

Although chronic cerebral hypoperfusion (CCH) may affect Alzheimers disease (AD) pathogenesis, the mechanism remains elusive. In the present study, we investigated the role of CCH on an AD mouse model in neurovascular unit, cerebrovascular remodeling, and neurovascular trophic coupling. Moreover, examined protective effect of galantamine. Alzheimers disease transgenic mice (APP23) were subjected to bilateral common carotid arteries stenosis with ameroid constrictors for slowly progressive cerebral hypoperfusion. CCH exacerbated neuronal loss and decrease of α7 subunit of nicotinic acetylcholine receptors (α7-nAChRs) expression in hippocampus and thalamus at 12 months. Meanwhile, CCH greatly induced advanced glycation end products expression, and blood-brain barrier leakage through observing IgG and MMP9 expressions. Furthermore, a significant number of dramatic enlarged cerebral vessels with remodeling, BDNF/TrkB decreased in neurovascular trophic coupling. The present study demonstrated that CCH strongly enhanced primary AD pathology including neurodegeneration, neurovascular unit disruption, cerebrovascular remodeling and neurovascular trophic coupling damage in AD mice, and that galantamine treatment greatly ameliorated such neuropathologic abnormalities.

Effects of Pretreatment with Warfarin or Rivaroxaban on Neurovascular Unit Dissociation after Tissue Plasminogen Activator Thrombolysis in Ischemic Rat Brain.

BACKGROUND Warfarin and rivaroxaban are highly effective in reducing stroke risk in patients with atrial fibrillation (AF). However, their effects on anticoagulation and neurovascular unit (NVU) change remain elusive. In this study, we assessed the risks and benefits of pre-treatment with warfarin or rivaroxaban after tissue-type plasminogen activator (tPA) thrombolysis in ischemic rat brain. METHODS Pre-treatment with warfarin (.2 mg/kg/day), low dose rivaroxaban (60 mg/kg/day), high dose rivaroxaban (120 mg/kg/day) or vehicle was performed for 2 weeks, transient middle cerebral artery occlusion (tMCAO) was induced for 90 min, then followed by reperfusion with tPA. At 24 hours (h) after reperfusion, we observed the changes of matrix metalloproteinase-9 (MMP-9), tissue factor, caspase 3 and NVU dissociation. RESULTS Prothrombin time (PT) was significantly prolonged in the warfarin and rivaroxaban pretreated groups. MMP-9 expression greatly increased in the warfarin group, and this was reduced in the rivaroxaban groups compared with the vehicle group. Tissue factor expression remarkably decreased in the warfarin and rivaroxaban groups. The number of caspase 3-positive cells had no difference among all the groups. Marked dissociations between astrocyte foot processes and the basal lamina or pericytes were observed in the warfarin pretreated group, but such dissociations were improved in the rivaroxaban groups. CONCLUSIONS Our present study shows that pre-treatment with rivaroxaban was noninferior to warfarin in the anticoagulation, but a lower risk of NVU dysfunction and dissociation after tPA treatment in rivaroxaban. This finding could partly explain the mechanism of reducing hemorrhagic complications by rivaroxaban in clinical studies.

Chronic Cerebral Hypoperfusion Accelerates Alzheimer's Disease Pathology with Cerebrovascular Remodeling in a Novel Mouse Model.

Recently, aging societies have been showing an increasingly strong relationship between Alzheimers disease (AD) and chronic cerebral hypoperfusion (HP). In the present study, we created a new mouse model for AD with HP, and investigated its clinical and pathological characteristics. Alzheimers disease transgenic mice (APP23) were subjected to bilateral common carotid arteries stenosis with ameroid constrictors for slowly progressive cerebral HP. In contrast to simple APP23 mice, cerebral HP exacerbated motor and cognitive dysfunctions with white matter lesions and meningo-parenchymal amyloid-β (Aβ) burdens. Strong cerebrovascular inflammation and severe amyloid angiopathy with cerebrovascular remodeling were also observed in APP23 + HP mouse brains. An acetylcholinesterase inhibitor galantamine improved such clinical dysfunctions, retrieved above neuropathological characteristics, and enhanced nicotinic acetylcholine receptor (nAChR)-binding activity. The present study demonstrates that chronic cerebral HP enhanced cognitive/motor dysfunctions with parenchymal/cerebrovascular Aβ accumulation and cerebrovascular remodeling. These neuropathological abnormalities were greatly ameliorated by galantamine treatment associated with nAChR-mediated neuroprotection by allosterically potentiating ligand action.

Aberrant distributions of nuclear pore complex proteins in ALS mice and ALS patients

Nuclear pore complexes (NPCs) play important roles in traffic of molecules between the nucleus and cytoplasm, aberrant distributions of components of NPCs were demonstrated in C9orf72 amyotrophic lateral sclerosis (C9-ALS) patients, but it is elusive whether such abnormities are also the case with other cause of ALS disease. In the present study, we investigated the spatiotemporal distributions of RanGAP1 and 4 representative nucleoporins (GP210, NUP205, NUP107 and NUP50) of NPCs in human Cu/Zn superoxide dismutase-1 mutation transgenic (SOD1-Tg) mice and sporadic ALS patients. Compared with wild type (WT), these proteins displayed age-dependent and progressive nuclear precipitations, and cytoplasmic aberrant expressions in motor neurons of lumbar cord in SOD1-Tg mice from 10 to 18weeks (W). Double immunofluorescent analysis showed abnormal nuclear retention and apparent co-localizations of RanGAPl with NUP205 and NUP205 with NUPl07, meanwhile, GP210 with NUP205 mainly co-localized in the nuclear envelope (NE) of motor neurons. Furthermore, RanGAP1, GP210 and NUP50 showed similarly abnormal nuclear precipitations and cytoplasmic upregulations in SOD1-Tg mice and ALS patients, moreover, aberrant co-localizations of RanGAP1 with TDP-43 and NUP205 with TDP-43 were also observed in motor neurons. The present study indicated that the mislocalization of these proteins of NPCs may underlie the pathogenesis of ALS both in SOD1-Tg mice and human sporadic ALS patients, and these dysfunctions may be a fundamental pathway for ALS that is not specific only in C9-ALS but also in SOD1-ALS, which may be amenable to pharmacotherapeutic intervention.

Reduction of intracerebral hemorrhage by rivaroxaban after tPA thrombolysis is associated with downregulation of PAR‐1 and PAR‐2

This study aimed to assess the risk of intracerebral hemorrhage (ICH) after tissue‐type plasminogen activator (tPA) treatment in rivaroxaban compared with warfarin‐pretreated male Wistar rat brain after ischemia in relation to activation profiles of protease‐activated receptor‐1, ‐2, ‐3, and ‐4 (PAR‐1, ‐2, ‐3, and ‐4). After pretreatment with warfarin (0.2 mg/kg/day), low‐dose rivaroxaban (60 mg/kg/day), high‐dose rivaroxaban (120 mg/kg/day), or vehicle for 14 days, transient middle cerebral artery occlusion was induced for 90 min, followed by reperfusion with tPA (10 mg/kg/10 ml). Infarct volume, hemorrhagic volume, immunoglobulin G leakage, and blood parameters were examined. Twenty‐four hours after reperfusion, immunohistochemistry for PARs was performed in brain sections. ICH volume was increased in the warfarin‐pretreated group compared with the rivaroxaban‐treated group. PAR‐1, ‐2, ‐3, and ‐4 were widely expressed in the normal brain, and their levels were increased in the ischemic brain, especially in the peri‐ischemic lesion. Warfarin pretreatment enhanced the expression of PAR‐1 and PAR‐2 in the peri‐ischemic lesion, whereas rivaroxaban pretreatment did not. The present study shows a lower risk of brain hemorrhage in rivaroxaban‐pretreated compared with warfarin‐pretreated rats following tPA administration to the ischemic brain. It is suggested that the relative downregulation of PAR‐1 and PAR‐2 by rivaroxaban compared with warfarin pretreatment might be partly involved in the mechanism of reduced hemorrhagic complications in patients receiving rivaroxaban in clinical trials.

Disruption of White Matter Integrity by Chronic Cerebral Hypoperfusion in Alzheimer’s Disease Mouse Model

A rapidly progressing aging society has raised attention to white matter lesions in Alzheimers disease. In the present study, we applied an AD plus cerebral hypoperfusion (HP) mouse model and investigated the alternation of key protein molecules in the nodal, paranodal, and intermodal sites in the white matter as well as the efficacy of galantamine. Cerebral HP was induced in APP23 mice by bilateral common carotid arteries stenosis with ameroid constrictors. Compared with the wild type and simple APP23 mice, APP23 + HP mice showed a progressive loss of MAG and NF186 from 6 to 12 months, broken misdistribution of MBP, and extended relocation of Nav1.6 and AnkG beyond the primary nodal region in the corpus callosum. Such abnormal neuropathological processes were retrieved with galantamine treatment. The present study demonstrated that cerebral HP strongly disrupted white matter integrity (WMI) at intermodal, paranodal, and Ranviers nodal sites which may be associated with cognitive decline. Galantamine treatment significantly protected such WMI probably by allosterically potentiating ligand action.

Estimation of the presence of small dense lipoprotein cholesterol in acute ischemic stroke

Small dense low-density lipoprotein (sdLDL) is an established risk factor in ischemic heart disease. However, its clinical significance in acute ischemic stroke (AIS) is uncertain. This study evaluates the prognostic value of the presence of sdLDL in patients with AIS by determining whether it contributes to clinical outcome or not. We studied 530 consecutive patients admitted within the first 48 hours after onset of ischemic stroke and 50 corresponding controls. Serum lipid parameters were measured on admission by standard laboratory methods. The percentage of AIS patients with sdLDL was significantly higher than the one of matched controls with sdLDL. Concerning comparisons between AIS patients with or without sdLDL, the percentages of males and patients with histories of smoking, hypertension, and cardiovascular disease were significantly higher in AIS patients with sdLDL. Concerning the grade of severity, modified Rankin Scale (mRS) on discharge was significantly higher in AIS patients with sdLDL. On logistic regression analysis, age (OR=2.29, P<0.001), male gender (OR=0.49, P<0.01), history of atrial fibrillation (OR=3.46, P<0.001), and the presence of sdLDL (OR=1.59, P<0.05) were significantly associated with poor prognosis (mRS on discharge >3). Our study showed that the presence of sdLDL might be independently associated with a poor prognosis after AIS.

Peripheral arterial endothelial dysfunction of neurodegenerative diseases

This study evaluates endothelial functions of neurodegenerative diseases such as amyotrophic lateral sclerosis (ALS), Parkinsons disease (PD), progressive supranuclear palsy (PSP), multiple system atrophy (MSA) and spinocerebellar ataxia (SCA). The reactive hyperemia index (RHI) of peripheral arterial tonometry and serological data were compared between age- and gender-matched normal controls (n=302) and five disease groups (ALS; n=75, PD; n=180, PSP; n=30, MSA; n=35, SCA; n=53). Correlation analyses were performed in ALS with functional rating scale-revised (FRS-R), and in PD with the Hehn-Yahr scale (H-Y) and a heart to mediastinum ratio using (123)I-MIBG scintigraphy (MIBG). The RHI of ALS and PD, but not of PSP, MSA or SCA, were significantly lower than normal controls (p<0.01). ALS showed a negative correlation of RHI with serum triglycerides (TG) and immunoreactive insulin (IRI) levels, but not with disease severity (FRS-R) or rates of disease progression (∆FRS-R). On the other hand, PD showed a negative correlation of RHI with a progressive disease severity (H-Y) and a positive correlation of RHI with early/delayed MIBG scintigraphy, but not with serological data. The present study demonstrated significant declines of peripheral arterial endothelial functions in ALS and PD. The RHI of ALS was more correlated with disease duration and serum parameters while the RHI of PD was more correlated with disease severity and MIBG, suggesting different mechanisms of endothelial dysfunction.

'PrP systemic deposition disease': clinical and pathological characteristics of novel familial prion disease with 2-bp deletion in codon 178.

A novel TYPE of prion disease associated mainly with autonomic‐sensory polyneuropathy was reported by us previously.

High Incidence of Dementia Conversion than Stroke Recurrence in Poststroke Patients of Late Elder Society

BACKGROUND This study investigated the incidence of current poststroke dementia (PSD), the annual conversion ratio into PSD, and the risk factors for conversion. METHODS In a 4.8-year follow-up period, 112 poststroke patients (ischemic stroke and intracerebral hemorrhage) were retrospectively investigated in cognitive examinations. They were categorized into 3 subgroups: converters into PSD, nonconverters who maintained their normal cognitive functions, and reverters who recovered to the normal mentality range. The clinical and demographic characteristics of these 3 subgroups were analyzed. RESULTS Among all 112 poststroke patients (61.6% male, 73.6 ± 10.4 years old), 16.1% had PSD. During the follow-up period, a part of the normal baseline mentality group (83.9% of 112 original patients) newly developed PSD (subdivided into converters) with an annual conversion rate of 7.6%. The reversion rate from the baseline PSD group was 11.3%. There were significant differences in age (P < .05), baseline mini-mental state examination scores (P < .05), body mass index (P < .05), and periventricular and deep white matter hyperintensity grades (P < .05 and P = .01, respectively) between converters and nonconverters. The annual rate of stroke recurrence was only 2.2% in all stroke subtypes. CONCLUSIONS In comparison with stroke recurrence (2.2%), 7.6% of the annual PSD conversion rate was very high. Therefore, prevention of direct conversion into PSD without stroke recurrence may be another important aspect of poststroke clinics, especially in late elder society.