In-vitro Characterization of YM872, a Selective,Potent and Highly Water-soluble α-Amino-3-hydroxy-5-methylisoxazole-4-propionate Receptor Antagonist

The in-vitro pharmacological properties of (2,3-dioxo-7-(1H-imidazol-***1-yl)-6-nitro-1,2,3,4-tetrahydro-1-quinoxalinyl)-acetic acid monohydrate, YM872, a novel and highly water-soluble α-amino-3-hydroxy-5-methylisoxazole-4-propionate (AMPA)-receptor antagonist were investigated. YM872 is highly water soluble (83 mg mL^?1 in Britton-Robinson buffer) compared with 2,3-dihydroxy-6-nitro-7-sulphamoyl-benzo(F)quinoxaline (NBQX), 6-(1H-imidazol-1-yl)-7-nitro-2,3(1H,4H)-quinoxalinedione hydrochloride (YM90K) or 6-cyano-7-nitroquinoxa-line-2,3-dione (CNQX). YM872 potently inhibits [³H]AMPA binding with a K_i (apparent equilibrium dissociation constant) value of 0.096 ± 0.0024 μM. However, YM872 had very low affinity for other ionotropic glutamate receptors, as measured by competition with [³H]kainate (high-affinity kainate binding site, concentration resulting in half the maximum inhibition (IC50) = 4.6 ± 0.14 μm), [³H]glutamate (N-methyl-D-aspartate (NMDA) receptor glutamate binding site, IC50 > 100 μM) and [³H]glycine (NMDA receptor glycine-binding site, IC50 > 100 μM). YM872 competitively antagonized kainate-induced currents in Xenopus laevis oocytes which express rat AMPA receptors, with a pA₂ value of 6.97 ± 0.01. In rat hippocampal primary cultures, YM872 blocked a 20-μM AMPA-induced increase of intracellular Ca²⁺ concentration with an IC50 value of 0.82 ± 0.031 μM, and blocked 300-μM kainate-induced neurotoxicity with an IC50 value of 1.02 μM. These results show that YM872 is a potent and highly water-soluble AMPA antagonist with great potential for treatment of neurodegenerative disorders such as stroke.     

Hyperbaric oxygen stimulates cell proliferation and normalizes multidrug resistance protein-2 protein localization in primary rat hepatocytes

Hyperbaric oxygen therapy (HBO) has been used for many clinical treatments, including primary liver non-function. However, the cellular mechanism by which HBO treatment ameliorates liver function is not understood. Therefore, the purpose of this study was to elucidate this cellular mechanism using primary cultured rat hepatocytes in in vitro studies. Hepatocytes were treated with HBO at 1 day after plating, and the morphological and functional characteristics of bile canaliculi formed in cultured hepatocytes were observed by time-lapse microscopy. Multidrug resistance protein-2 localization was observed by confocal laser microscopy. In cultured hepatocytes, the labeling index in the HBO group at 2 days after treatment was significantly higher than that in the control group. In addition, the proliferating cellular nuclear antigen level in the HBO group was significantly higher than that in the control group. The contraction of the bile canaliculi in the HBO group was slower than in the control group and the dilatation of bile canaliculi in the HBO group was much larger than in the control group. Multidrug resistance protein-2 in the HBO group was localized at the apical membrane. These results show that HBO stimulates hepatocytes to proliferate and HBO normalizes multidrug resistance protein-2 localization to the apical membrane, which could dilate bile canaliculi.     

Masked ureteral duplication with ectopic ureter detected by magnetic resonance imaging

The usefulness of magnetic resonance imaging (MRI) in the detection of a masked duplex kidney system is described. A 9 year old girl was admitted to our hospital for urinary incontinence. She was found to possess an ectopic ureter associated with complete ureteral duplication. She had been evaluated for incontinence at several hospitals, but neither ultrasound sonography nor intravenous pyelography detected any abnormalities. Only cystoscopic examination and MRI detected the anomalies. Partial nephroureterectomy resolved the patient's incontinence. MRI is useful for the detection of ureteral duplication and should be used on cases in which this condition is suspected, prior to performing invasive procedures.     

Correlation of Middle Cerebral Artery Tortuosity with Successful Recanalization Using the Merci Retrieval System with or without Adjunctive Treatments

The Merci retrieval system is a useful modality for the recanalization of acute cerebral artery occlusion. However, it remains unclear whether the tortuosity of the middle cerebral artery (MCA) plays a role in successful recanalization. In this study, we investigated the association between the shape of the horizontal MCA segment (M1) and successful recanalization using the Merci retrieval system with or without adjunctive treatments. Twenty-three patients with M1 occlusion underwent thrombectomy using the Merci retrieval system with or without adjunctive treatments between July 2010 and July 2012. The anteroposterior view of final angiograms was used to measure the M1 curve angles. M1 with a curve angle measuring < 100° was defined as arch-type M1, whereas that with a curve angle measuring ≥ 100° was defined as straight-type M1. Angiographic findings were evaluated on the basis of the thrombolysis in cerebral infarction grade; grade 2B or 3 corresponds to successful recanalization. Eight patients had arch-type M1 and 15 patients had straight-type M1. Successful recanalization was achieved in 2 patients (25%) with arch-type M1 and 12 patients (80%) with straight-type M1 (p = 0.023). The mean M1 curve angle was significantly greater in the 14 patients in whom successful recanalization was achieved than in the 9 patients in whom it was not achieved (129 ± 21° vs. 93 ± 29°, p = 0.002). Arch-type M1 was an independent predictive factor of unsuccessful recanalization (odds ratio, 0.045; 95% confidence interval, 0.03–0.696). A tortuous M1 was associated with unsuccessful recanalization by the Merci retrieval system, even when adjunctive treatments were used.     

Low prevalence of hepatitis C virus infection in patients with auto-immune hepatitis type 1

Hepatitis C virus (HCV) antibodies were measured in 28 patients with auto-immune hepatitis type 1 using six different assay kits, three for C100–3 antibody and three for second generation HCV antibody, and two confirmatory tests to determine the prevalence of HCV infection in auto-immune hepatitis. These patients were confirmed to have human leucocyte antigen DR 4 or 2 which is susceptible to auto-immune hepatitis in Japanese. Of the 28 patients, four (14.3%) were positive for HCV antibody in all assays and reacted positively in at least one of the two confirmatory tests, indicating a true positive finding. Eight were positive for HCV antibody only by the Ortho ELISA kit and were negative in both confirmatory tests. The cut-off level for these results was low and became negative soon after the patients received corticosteroid treatment. Thus, these eight patients are presumed to be false-positive reactors. Hepatitis C virus RNA was detected in the serum of two of the four patients with HCV antibody and in none of 24 patients without HCV antibody. No significant difference was observed between the patients with and without HCV antibody in terms of clinical background, liver function tests and auto-antibodies. Our results showed that the prevalence of a past or present HCV infection in patients with auto-immune hepatitis in Japan is low; thus, auto-immune hepatitis is thought to be distinct from hepatitis type C. However, it is also suggested that HCV infection can potentially trigger auto-immune hepatitis.     

Epidemiology of genotypes of hepatitis C virus in Japanese patients with type C chronic liver diseases: A multi-institution analysis

Sixteen medical institutions in Japan collaborated in this study of the epidemiology of hepatitis C virus (HCV) genotypes. A total of 4176 patients with type C chronic liver disease, from the four main islands of Japan, were evaluated. Of those evaluated, 2794 had chronic hepatitis, 727 had liver cirrhosis and 655 had hepatocellular carcinoma. The HCV genotype of the patients was determined by an enzyme-linked immunosorbent assay based on serological genotype 1- and 2-specific recombinant peptides (SG-1 and SG-2, respectively) of the NS4 region. The prevalence of SG-1 and SG-2 HCV was similar in the four main islands of Japan. SG-1 HCV predominated in each disease category (69–76%). The percentage of patients with SG-1 HCV increased by 7%, while that of patients with SG-2 HCV decreased by 7%, as liver disease progressed in severity from chronic hepatitis to carcinoma (P < 0.001). Patients with either SG-1 or SG-2 had a similar mean age and history of blood transfusion. In conclusion, SG-1 HCV was found to predominate in Japan, and the HCV genotype was found to be related to the stage of hepatitis C disease.