The mechanisms of NO inhibition of CaMK [Ca(2+)/CaM (calmodulin)-dependent protein kinase] II activity were studied. In rat pituitary tumour GH3 cells, TRH [thyrotrophin (TSH)-releasing hormone]-stimulated phosphorylation of nNOS [neuronal NOS (NO synthase)] at Ser(847) was sensitive to an inhibitor of CaMKs, KN-93, and was enhanced by inhibition of nNOS with 7NI (7-nitroindazole). Enzyme activity of CaMKII following in situ treatment with 7NI was also increased. The in vitro activity of CaMKII was inhibited by co-incubation either with nNOS and L-arginine or with NO donors SNAP (S-nitroso-N-acetyl-DL-penicillamine) and DEA-NONOate [diethylamine-NONOate (diazeniumdiolate)]. Once inhibited by these treatments, CaMKII was observed to undergo full reactivation on the addition of a reducing reagent, DTT (dithiothreitol). In transfected cells expressing CaMKII and nNOS, treatment with the calcium ionophore A23187 further revealed nNOS phosphorylation at Ser(847), which was enhanced by 7NI and CaMKII S-nitrosylation. Mutated CaMKII (C6A), in which Cys(6) was substituted with an alanine residue, was refractory to 7NI-induced enhancement of nNOS phosphorylation or to CaMKII S-nitrosylation. Furthermore, we could identify Cys(6) as a direct target for S-nitrosylation of CaMKII using MS. In addition, treatment with glutamate caused an increase in CaMKII S-nitrosylation in rat hippocampal slices. This glutamate-induced S-nitrosylation was blocked by 7NI. These results suggest that inactivation of CaMKII mediated by S-nitrosylation at Cys(6) may contribute to NO-induced neurotoxicity in the brain.

Although the sensitive detection of putaminal iron deposition by T2*-weighted imaging (T2*-WI) is of diagnostic value for multiple system atrophy (MSA), the diagnostic significance of the pontine hot-cross bun (HCB) sign with increased ferritin-bound iron in the background remains unknown. We retrospectively evaluated the cases of 33 patients with cerebellar-form MSA (MSA-C) and 21 with MSA of the parkinsonian form (MSA-P) who underwent an MRI study with a 1.5-T system. Visualization of the HCB sign, posterior putaminal hypointensity and putaminal hyperintense rim on T2*-WI was assessed by two neurologists independently using an established visual grade, and were compared with those on T2-weighted imaging (T2-WI). The visual grade of pontine and putaminal signal changes was separately assessed for probable MSA (advanced stage) and possible MSA (early stage). T2*-WI demonstrated significantly higher grades of HCB sign than T2-WI (probable MSA-C, n = 27, p < 0.001; possible MSA-C, n = 6, p < 0.05; probable MSA-P, n = 13, p < 0.01). The visual grade of the HCB sign on T2*-WI in the possible MSA-C patients was comparable to that in the probable MSA-C patients. Although the HCB sign in MSA-P was of lower visual grade than in MSA-C even on T2*-WI, some patients showed evolution of the HCB sign preceding the appearance of the putaminal changes. These findings suggest that T2*-WI is of extreme value for detecting the HCB sign, which is often cited as a hallmark of MSA. The appearance of the HCB sign on T2*-WI might not only support but also improve the diagnosis of MSA.

A 20-year-old Japanese woman had an attack of acute intermittent porphyria (AIP). Magnetic resonance imaging (MRI) revealed symmetrical lesions in the cerebrum and cerebellar hemisphere, corresponding to posterior reversible encephalopathy syndrome (PRES). Our administration of heme arginate gradually improved the clinical condition associated with AIP and the level of metabolite of nitric oxide (NO), which is a vascular dilator. Repeated MRI and magnetic resonance angiography revealed exacerbated PRES, part of which showed a small infarction, accompanied by progressive vasoconstriction. These findings suggest that the recovery of NO by heme replacement alone is insufficient for preventing brain damage during an AIP attack.

Background Both fragile X-associated tremor/ataxia syndrome (FXTAS) and late-onset neuronal intranuclear inclusion disease (NIID) show CGG/GGC trinucleotide repeat expansions. Differentiating these diseases are difficult because of the similarity in their clinical and radiological features. It is unclear that skin biopsy can distinguish NIID from FXTAS. We performed a skin biopsy in an FXTAS case with cognitive dysfunction and peripheral neuropathy without tremor, which was initially suspected to be NIID. Case presentation The patient underwent neurological assessment and examinations, including laboratory tests, electrophysiologic test, imaging, skin biopsy, and genetic test. A brain MRI showed hyperintensity lesions along the corticomedullary junction on diffusion-weighted imaging (DWI) in addition to middle cerebellar peduncle sign (MCP sign). We suspected NIID from the clinical picture and the radiological findings, and performed a skin biopsy. The skin biopsy specimen showed ubiquitin- and p62-positive intranuclear inclusions, suggesting NIID. However, a genetic analysis for NIID using repeat-primed polymerase chain reaction (RP-PCR) revealed no expansion detected in the Notch 2 N-terminal like C (NOTCH2NLC) gene. We then performed genetic analysis for FXTAS using RP-PCR, which revealed a repeat CGG/GGC expansion in the FMRP translational regulator 1 (FMR1) gene. The number of repeats was 83. We finally diagnosed the patient with FXTAS rather than NIID. Conclusions For the differential diagnosis of FXTAS and NIID, a skin biopsy alone is insufficient; instead, genetic analysis, is essential. Further investigations in additional cases based on genetic analysis are needed to elucidate the clinical and pathological differences between FXTAS and NIID.

Multiple system atrophy (MSA) is a sporadic neurodegenerative disease that is pathologically characterized by α-synuclein positive glial cytoplasmic inclusions in oligodendrocytes. The clinical diagnosis of MSA is often challenging as there are no established biomarkers and diagnoses are now based on clinical findings alone. At present, the etiology and pathogenesis of MSA are unclear. It has been reported that dysregulation of microRNA (miRNA/miR) serves an important role in neurodegenerative disorders including Alzheimer's disease, Parkinson's disease and amyotrophic lateral sclerosis. The miRNA profile of patients with MSA remains to be established. The present study investigated the serum miRNA expression level of 10 patients with MSA, using microarray chips including 668 miRNAs. It was identified that 50 miRNAs were significantly upregulated and 17 miRNAs were significantly downregulated in the serum of the patients with MSA. The most upregulated miRNA was miR-16, which may induce the accumulation of α-synuclein. The target genes of some miRNAs upregulated in MSA (including miR-17, 20a, 24, 25, 30d and 451) were associated with autophagy-associated molecules. The present study concluded that the expression pattern of miRNAs may be a clinical biomarker for MSA and targeting these miRNAs may provide a novel treatment for MSA.