Plasma amyloid-ß oligomers level is a biomarker for Alzheimer's disease diagnosis.

Amyloid beta (Aß), especially Aß oligomers, is important in Alzheimer's disease (AD) pathogenesis. We studied plasma Aß(40), Aß(42), and Aß oligomers levels in 44 AD patients and 22 non-demented controls. Cognitive functions were assessed by Chinese version of mini-mental state examination (MMSE), Abbreviated Metal Test (AMT), Alzheimer's Disease Assessment Scale Cognitive Subscale (ADAS-cog). Plasma Aß monomers and oligomers levels were measured by ELISA. We found that the median plasma Aß(40) and Aß(42) levels were similar between AD and controls, and without significant correlation with cognition. Plasma Aß oligomers level was higher in AD than controls (642.54 ng/ml [range 103.33-2676.93] versus 444.18 ng/ml [range 150.19-1311.18], p=0.047), and negatively correlated with cognition. In multivariate logistic regression analysis, the highest tertile of Aß oligomers levels showed an increased risk of AD than the combined group of middle and lowest tertiles (OR=8.85, p=0.013), after adjustment of gender, age and APOE4 genotype. Increased plasma Aß oligomers level was associated with decreased MMSE and AMT scores (p=0.037, p=0.043, respectively) and increased ADAS-cog score (p=0.036), suggesting negative correlation with cognitive function. We concluded that plasma Aß oligomers level is an useful biomarker for AD diagnosis.

Estrogenic phenol and catechol metabolites of PCBs modulate catechol-O-methyltransferase expression via the estrogen receptor: potential contribution to cancer risk.

Commercial PCB mixtures have been shown to induce liver tumors in female rats and this effect has been attributed to the effects of PCBs on estrogen metabolism. Catechol metabolites of PCBs are potent inhibitors of COMT activity and are likely to contribute significantly to reduced clearance of genotoxic catechol metabolites of estrogen. The effect of PCB metabolites on COMT expression in cultured cells was investigated to explore potential mechanisms by which PCB exposure alters catechol estrogen clearance. We hypothesize that estrogenic PCB metabolites may contribute to reduction of COMT expression via interaction with the estrogen receptor. To test this hypothesis, human MCF-7 cells were exposed to PCB analogues and the expression of COMT determined. Western blot analysis demonstrated that COMT protein levels were statistically significantly reduced by both the phenolic and the catechol compounds, an effect which was abolished by the anti-estrogen, ICI182780. The above suggests that COMT levels may be reduced by estrogenic PCB metabolites, via interactions between PCB metabolites and the ER. It supports the hypothesis that both phenolic and catechol metabolites of PCBs may contribute to PCB-mediated carcinogenesis through reduction of COMT levels and activities and subsequent reduction in clearance of endogenous and xenobiotic catechols.

Aquaporin-4 autoantibodies cause asymptomatic aquaporin-4 loss and activate astrocytes in mouse.

BACKGROUND: Neuromyelitis optica (NMO) is a central nervous system inflammatory demyelinating disorder. Up to 90% of patients are seropositive for aquaporin-4 autoantibodies (AQP4 Ab). The pathogenetic mechanisms underlying clinical onset and relapse of NMO are uncertain. OBJECTIVE: Study the pathogenicity of AQP4 Ab in the absence of complement activation. METHODS: Female C57BL/6N mice (human IgG cannot activate mouse complements) pretreated with complete Freund's adjuvant (CFA, day 0) and pertussis toxin (PTx, day 0 and day 2) were transferred with IgG isolated from serum of healthy subjects or NMO patients (AQP4 Ab-positive or negative) intraperitoneally (day 7-9). Mice were observed for signs of experimental autoimmune encephalomyelitis (EAE) by standard 6-grade EAE scores. Spinal cord was obtained at day 11 for immunohistochemistry. RESULTS: None of the mice had clinical signs of encephalomyelitis, inflammatory cells infiltration or demyelination of spinal cord. CFA and PTx induce BBB breakdown evidenced by leakage of human IgG into cord parenchyma. Patchy areas of AQP4 loss were observed in spinal cord of mice transferred with IgG from AQP4 Ab-positive NMO patients but not in mice transferred with IgG from AQP4 Ab-negative NMO patients or healthy subjects; but there was no loss of glial fibrillary acidic protein immunoreactivity in all mice. Markedly increased proliferation of astrocytic processes suggestive of astrocytic activation was observed in mice transferred with IgG from AQP4 Ab-positive patients. CONCLUSION: AQP4 Ab cause asymptomatic AQP4 loss and astrocytic activation but not myelitis, demyelination or astrocytic cytotoxicity in spinal cord of mouse in the absence of complement activation.

Brain involvement in neuromyelitis optica spectrum disorders.

BACKGROUND: Neuromyelitis optica spectrum disorders (NMOSDs) are severe inflammatory demyelinating disorders of the central nervous system. Brain involvement is increasingly recognized. OBJECTIVE: To study brain involvement in NMOSDs among Hong Kong Chinese patients. DESIGN: Retrospective study of patients with NMOSDs. SETTING: Tertiary medical center in Hong Kong. Patients  Thirty-four Hong Kong Chinese patients with NMOSDs of 2 years or longer were recruited. INTERVENTIONS: Brain and spinal cord magnetic resonance imaging was performed during NMOSD attacks and was repeated yearly for the first 3 years. MAIN OUTCOME MEASURES: We evaluated clinical features of NMOSDs associated with brain involvement and brain lesions on magnetic resonance imaging. RESULTS: Among 34 patients with NMOSDs of 2 years or longer, 20 (59%) had brain involvement. The mean age at onset among these 20 patients was 45.6 years (age range, 19-67 years); 18 were women. Eleven patients (32% of all the patients with NMOSDs) had clinical manifestation of brain involvement, 19 patients (56%) had brain abnormalities on magnetic resonance imaging consistent with inflammatory demyelination, and 2 patients (6%) fulfilled criteria for multiple sclerosis. Clinical manifestation of brain involvement included the following: trigeminal neuralgia; vomiting, vertigo, ataxia, dysphagia, and tetraparesis from lesions around the third and fourth ventricles and aqueduct; homonymous hemianopia, aphasia, hemiparesis, and cognitive impairment from extensive hemispheric white matter lesions; and ataxia, diplopia, hiccups, facial sensory loss, internuclear ophthalmoplegia, hemisensory loss, and hemiparesis from other lesions in the midbrain, pons, cerebellar peduncles, and medulla. Eight patients (24%) developed brainstem encephalitis clinically, and brainstem encephalitis was the initial clinical manifestation in 6 patients (18%). Brain abnormalities on magnetic resonance imaging were detected in brainstem in 15 patients (44%), hemispheric periventricular white matter in 7 patients (21%), deep white matter in 7 patients (21%), corpus callosum in 4 patients (12%), subcortical white matter in 3 patients (9%), thalamus in 2 patients (6%), hypothalamus in 1 patient (3%), basal ganglia in 1 patient (3%), internal capsule in 1 patient (3%), periaqueductal gray matter in 1 patient (3%), and around the third and fourth ventricles in 1 patient (3%); large confluent lesions were detected in 2 patients (6%). CONCLUSION: Brain involvement manifesting clinically as brainstem encephalitis is common among Hong Kong Chinese patients with NMOSDs.

Clinical outcome of relapsing remitting multiple sclerosis among Hong Kong Chinese.

BACKGROUND: Clinical outcome of Chinese relapsing remitting multiple sclerosis (RRMS) patients is uncertain. AIM: To study the long-term clinical outcome of Chinese RRMS patients. METHOD: RRMS patients with duration of 10 years or longer followed up in our hospital is retrospectively studied. RESULTS: 61 RRMS patients (75% female) were studied. Their mean symptom onset age was 25.9 years and mean duration was 20.6 years (range 10-33); 36% patients had received ß-interferon and 30% azathioprine. Their mean EDSS scores were 3.3 (range 1-7) and 4.7 (range 1-8) at 10 years and latest follow-up (mean duration 20.6 years) respectively. At 10 years, 30% patients had EDSS score ≤2, 34% EDSS 2.5-3.5, 20% EDSS 4.0-5.5 and 16% ≥6; 18% developed SPMS. At latest follow-up, 15% patients had EDSS ≤2, 20% EDSS 2.5-3.5, 19% EDSS 4.0-5.5 and 46% ≥6.0; 53% developed SPMS. The median time from symptom onset to EDSS 6 was 22 years. No differences were detected in demographic characteristics, presenting neurological features, number of attacks in first 2 years, neuroradiological findings and disease modifying therapies between patients with EDSS <6 and ≥6 at ten years. EDSS scores at 10 years and latest follow-up were similar for patients who had received ß-interferon and those who had not. CONCLUSION: Hong Kong Chinese RRMS patients may have worse long-term clinical outcome than Caucasian patients.

Aquaporin-4 water channel expression by thymoma of patients with and without myasthenia gravis.

BACKGROUND: Neuromyelitis optica (NMO) is a serious idiopathic inflammatory demyelinating disorder characterized by acute transverse myelitis and optic neuritis. A significant proportion of NMO patients are seropositive for NMO-IgG, an autoantibody targeting aquaporin-4 (AQP4) water channel. Paraneoplastic NMO associated various tumors were recently reported. AIM: We studied the expression of AQP4 by thymoma from patients with and without myasthenia gravis (MG). METHODS: Thymoma obtained from thymomectomy in patients with and without MG were studied by immunohistochemistry and western blot. RESULTS: Ten thymoma patients (9 with MG) and two control patients without thymoma or MG were studied. Immunohistochemistry revealed AQP4 immunoreactivity in cell membrane of thymoma cells from all ten thymoma specimens whereas thymic tissues from patients without thymoma or MG were negative for AQP4 immunoreactivity. Western blot revealed that lysates of nine of the ten thymoma specimens reacted with anti-human AQP4 antibody with a band of ~30 kDa compatible with the molecular weight of AQP4. Interestingly, immunofluorescence revealed that IgG isolated from 2 NMO patients seropositive for NMO-IgG bound to cell membrane of thymoma cells from all ten thymoma specimens while IgG from healthy control subject did not. CONCLUSION: Thymoma cells of patients with and without MG express AQP4. AQP4 autoantibodies from serum of NMO patients bound to AQP4 expressed on thymoma cell membrane.