Diffusion Mediates Molecular Transport through the Perivascular Space in the Brain.

The perivascular space has been proposed as a clearance pathway for degradation products in the brain, including amyloid ß, the accumulation of which may induce Alzheimer's disease. Live images were acquired using a two-photon microscope through a closed cranial window in mice. In topical application experiments, the dynamics of FITC-dextran were evaluated from 30 to 150 min after the application and closure of the window. In continuous injection experiments, image acquisition began before the continuous injection of FITC-dextran. The transport of dextran molecules of different sizes was evaluated. In topical application experiments, circumferential accumulation around the penetrating arteries, veins, and capillaries was observed, even at the beginning of the observation period. No further increases were detected. In continuous injection experiments, a time-dependent increase in the fluorescence intensity was observed around the penetrating arteries and veins. Lower-molecular-weight dextran was transported more rapidly than higher-molecular-weight dextran, especially around the arteries. The largest dextran molecules were not transported significantly during the observation period. The size-dependent transport of dextran observed in the present study strongly suggests that diffusion is the main mechanism mediating substance transport in the perivascular space.

In Vivo Dynamic Movement of Polymerized Amyloid ß in the Perivascular Space of the Cerebral Cortex in Mice.

Disposition of amyloid ß (Aß) into the perivascular space of the cerebral cortex has been recently suggested as a major source of its clearance, and its disturbance may be involved in the pathogenesis of cerebral amyloid angiopathy and Alzheimer's disease. Here, we explored the in vivo dynamics of Aß in the perivascular space of anesthetized mice. Live images were obtained with two-photon microscopy through a closed cranial window. Either fluorescent-dye-labeled Aß oligomers prepared freshly or Aß fibrils after 6 days of incubation at 37 °C were placed over the cerebral cortex. Accumulation of Aß was observed in the localized perivascular space of the penetrating arteries and veins. Transportation of the accumulated Aß along the vessels was slow and associated with changes in shape. Aß oligomers were transported smoothly and separately, whereas Aß fibrils formed a mass and moved slowly. Parenchymal accumulation of Aß oligomers, as well as Aß fibrils along capillaries, increased gradually. In conclusion, we confirmed Aß transportation between the cortical surface and the deeper parenchyma through the perivascular space that may be affected by the peptide polymerization. Facilitation of Aß excretion through the system can be a key target in treating Alzheimer's disease.

Paradoxical Brain Embolism Caused by Isolated Pulmonary Arteriovenous Fistula Successfully Treated with Recombinant Tissue Plasminogen Activator.

Pulmonary arteriovenous fistula (PAVF), a vessel malformation connecting the pulmonary circulation to the systemic circulation while bypassing the pulmonary capillaries, can cause paradoxical cerebral infarction. It is often associated with hereditary hemorrhagic telangiectasia (HHT), a genetic disease characterized by multiple dermal, mucosal, and visceral telangiectasia causing recurrent bleeding. Paradoxical cerebral embolism caused by PAVF without HHT is rare. Here, we report a patient with isolated PAVF who experienced an ischemic stroke caused by a paradoxical embolism from deep venous thrombosis; the patient was successfully treated with recombinant tissue plasminogen activator. She presented with a decrease in arterial oxygen saturation to 91%, and lung disease was suspected. A PAVF was subsequently found in the right S6 region using contrast computed tomography. Interventional radiologists successfully occluded the shunt using 6 microcoils. PAVF should be considered when determining the pathogenesis of cerebral ischemia in patients with hypoxia, which can be the only symptom of PAVF.

Amyloid deposition and CBF patterns predict conversion of mild cognitive impairment to dementia.

Mild cognitive impairment (MCI) can include the transition from a normal state to dementia. To explore biomarkers for the development of dementia, we performed an 18-month follow-up study in 28 patients with amnestic MCI. Amyloid deposition was examined using PiB PET, and cerebral blood flow (CBF) was examined using SPECT. Cognitive function was periodically assessed. The rate of conversion to dementia was higher in the PiB-positive/equivocal group (74%) than in the PiB-negative group (33%) (p = 0.041). Perfusion SPECT was performed in 16 patients. MCI patients with an AD-characteristic pattern of reduced CBF had a higher PiB-positive/equivocal rate (82%) than those with a non-AD pattern (20%) (p = 0.018), and patients with an AD pattern had a higher conversion rate (82%) than those with a non-AD pattern (40%) (p = 0.094). Clinically, all PiB-positive converters were diagnosed as having Alzheimer's disease (AD), whereas PiB-negative converters were thought to have some form of dementia other than AD. Amyloid PET is useful for predicting conversion to AD in MCI patients. A pattern analysis of perfusion SPECT findings might also be helpful for predicting conversion to AD, but with a lower specificity.

An autopsy case of globular glial tauopathy presenting with clinical features of motor neuron disease with dementia and iron deposition in the motor cortex.

Globular glial tauopathy (GGT) is a 4-repeat (4R) tauopathy in which 4R tau accumulates to form globular glial inclusions (GGIs), predominantly in oligodendroglia. To date, little has been reported on iron deposits in patients with GGT. We report a case of GGT with iron deposits in a 78-year-old woman presenting with an 8-year history of slowly progressing limb weakness and cognitive decline. Susceptibility-weighted imaging revealed a low signal intensity in the right precentral gyrus, suggesting iron deposition. A clinical diagnosis of motor neuron disease with dementia was made 4 years after onset. At autopsy, gross pathological findings showed atrophy of the frontal and temporal lobes. A localized area of the precentral gyrus corresponding to the most severely affected limb showed the strongest atrophy, macroscopically, and displayed 4R tau-immunoreactive GGIs and microscopically many ferritin-immunoreactive neurons. We diagnosed this patient as having GGT. This is the first GGT case with iron deposition confirmed both radiologically and pathologically.

Multiple Cerebral Infarctions Accompanied by Subcortical and Subarachnoid Hemorrhaging in Bilateral Border Zone Areas in a Patient with Eosinophilic Granulomatosis with Polyangiitis.

Eosinophilic granulomatosis with polyangiitis (EGPA) is often associated with peripheral neuropathy, but reports of central nervous system involvement are quite rare. We herein report a patient with EGPA first identified as having hypereosinophilia who later developed asthma, eosinophilic otitis media, sinusitis, and hemorrhagic colitis. She subsequently developed hemiparesis. Head magnetic resonance imaging revealed multiple cerebral infarctions with subcortical and subarachnoid hemorrhaging colocalized at the bilateral border zone areas. She was diagnosed with EGPA-induced stroke and successfully treated with oral prednisolone. Inflammation in the small cerebral arteries in EGPA may induce bilateral border zone infarction with colocalizing subcortical and subarachnoid hemorrhaging.

Liver injury after methylprednisolone pulse therapy in multiple sclerosis is usually due to idiosyncratic drug-induced toxicity rather than autoimmune hepatitis.

BACKGROUND: In patients with multiple sclerosis (MS), development of hepatic injury has been sporadically reported after methylprednisolone (MP) pulse therapy. Some studies suggest autoimmune hepatitis, while other studies reported direct hepatotoxicity as a cause for hepatic injury. Here, we studied the pathological mechanism of such liver injury in patients with MS. METHODS: From 2005 to 2016, eight patients with MS developed liver injury after MP pulse therapy. Their average age was 38 years (range: 28-49 years, all female). Autoimmune antibodies were measured and a liver biopsy was performed in seven patients. RESULTS: Liver injury developed within two weeks in two patients and later (30-90 days after MP) in six patients. No hepatitis-related autoantibody or hepatitis virus were found. All cases were classified as hepatocellular injury and none as cholestatic or mixed. A liver biopsy in five cases revealed centrilobular necrosis with lobular infiltrates of inflammatory cells, suggesting drug-induced acute hepatitis. The biopsy findings in another case suggested a residual stage of acute hepatitis. Only one patient showed portal expansion with periportal fibrosis, suggesting autoimmune hepatitis. All patients recovered spontaneously or with only hepatoprotective drugs, although one patient with possible autoimmune hepatitis recovered slowly. CONCLUSION: Liver injury develops usually later than two weeks after MP treatment. The prognosis is good in most cases and rarely autoimmune hepatitis may be involved.

Successful treatment of hepatocellular carcinoma with lung metastasis using hepatic and bronchial artery infusion chemotherapy.

We herein report a case of hepatocellular carcinoma (HCC) with lung metastasis that was successfully treated with transcatheter arterial infusion chemotherapy via the hepatic and bronchial arteries. A 64-year-old man diagnosed with HCC in 2003 was treated with locoregional therapy followed by sorafenib for recurrent HCC. Tumor thrombosis and lung metastasis were noted in April 2012. We administered IA-call(®), a fine-powder formulation of cisplatin, via the hepatic and bronchial arteries. This therapy resulted in the disappearance of the lung metastases and a partial response to tumor thrombosis. The patient remained alive for 23 months after developing lung metastasis.