Search

Employment of a battery energy storage system to compensate for the generation-consumption mismatch is a vital element for a resilient microgrid. However, the frequent (i.e., short-term) cyclic activity and the abrupt current variations (i.e., high di/dt) have adverse effects on the energy-type battery's lifespan. On the other hand, the power-type supercapacitor energy storage system (SCES) has almost zero lifetime degradation when it is subjected to irregular charging/discharging patterns. Therefore, the hybridization between them can reduce battery stress levels. This study proposes a droop control algorithm with multiple segments for a SCES/battery hybrid energy storage system (HESS) that is employed in a solar/wind DC microgrid. The presented control scheme is decentralized since it avoids the central controller (CC) and the communication links between the controllers of SCES and battery units. To eliminate the short-term cyclic operation of the battery, the SCES regulates the bus voltage inside a narrow zone with a droop curve that exploits all its available energy capacity. Inside this zone, the battery is kept inactive. As soon as the bus voltage deviates from this band, the SCES enters the idle mode, and the battery is triggered following a droop curve different for charging or discharging mode to stabilize the bus voltage. To evaluate the effectiveness of the proposed system over a battery-only system and a hybrid SCES/battery system controlled with the classical droop method, a comparative analysis under different scenarios is presented. [ABSTRACT FROM AUTHOR]

Background: Multiple sclerosis (MS) is a chronic inflammatory disease that leads to progressive disability. Statins [hydroxymethylglutaryl-CoA (HMG-CoA) reductase inhibitors] are widely prescribed drugs in hypercholesterolemia. They exert immunomodulatory and neurotrophic effects and are attractive candidates for MS treatment due to reliable safety profiles and favorable costs. Studies of statins in a murine MS model and in open-label trials in MS have shown decreased disease severity. Objective: Our objective was to assess current evidence to support statin treatment in MS and clinically isolated syndrome (CIS). Methods: We conducted a systematic literature review of EMBASE, PubMed, and CINAHL databases, clinical trials registries, and unpublished conference meeting abstracts as well as reference lists between 1 and 8 June 2014 and repeated it on 1 December 2014. Randomized controlled trials (RCTs) of statins, in any form or dosage, as monotherapy or add-on to established therapy in relapsing-remitting MS (RRMS), progressive MS, and CIS were included. Data were extracted using pre-defined fields to measure study quality. Meta-analysis was performed with regards to pre-defined outcome measures of relapse activity, magnetic resonance imaging (MRI) activity, Expanded Disability Status Scale (EDSS) progression, and adverse events using a fixed-effects model due to low heterogeneity between studies. Results: Eight trials were included in the review [five of statin add-on to interferon (IFN)-β treatment in RRMS, one of statin monotherapy in CIS, one of statin monotherapy in optic neuritis (ON)/CIS, and one of statin monotherapy in secondary progressive MS (SPMS)]. Three trials with eligible characteristics had not been published in peer-reviewed journals and were therefore not included. Due to the low number of trials in CIS and SPMS, meta-analysis of primary outcomes was only performed for RRMS studies. Meta-analysis showed no significant effect of statin add-on to IFNβ therapy. Indeed, a trend towards an increase in disease activity was shown in the statin group with regards to new T2 lesions, proportion of patients with relapse, and whole brain atrophy but not for EDSS progression. In SPMS, statin monotherapy showed significant reduction in brain atrophy and disability progression but no effect on relapse rate. In CIS, a phase II trial showed no difference in relapse activity, MRI activity or risk of MS between statin monotherapy and placebo. In acute ON, statin monotherapy produced better visual outcome but no difference in relapse activity, MRI activity, or risk of MS. Conclusions: The pleiotropic effects and effects in the murine model of MS could not be converted to a proven effect in relapsing MS and hence statin therapy either as a monotherapy or in combination with IFNβ treatment for RRMS, and statin monotherapy for CIS cannot at present be recommended. However, indications are that statins may be beneficial in SPMS. The benefit thereof and whether this is due to a direct immunomodulatory and neuroprotective effect warrant further studies. [ABSTRACT FROM AUTHOR]

Optic neuritis (ON) is closely linked to multiple sclerosis (MS). It may, however, also be associated to a range of autoimmune or infectious diseases. The purpose of this study was to assess the differential diagnoses in patients with suspected ON. In this retrospective study, we reviewed the files of all patients referred to the Clinic of Optic Neuritis, Glostrup Hospital, University of Copenhagen, Denmark, between January 2000 and November 2011. All patients were referred by ophthalmologists with possible ON. Patients diagnosed with MS prior to referral were excluded from the study. A total of 643 patients were included in the study. Apart from ON, the most frequent diagnoses were tumors ( n = 15), ischemic or hypertensive neuropathies ( n = 13), and retinal or choroid disorders ( n = 9). Six patients were diagnosed with neuromyelitis optica. Rarer causes of visual loss were infections ( n = 5), giant cell arteritis ( n = 4), sarcoidosis ( n = 3), thyrotoxicosis ( n = 2), and hereditary or toxic neuropathies ( n = 2). Nine percent of patients referred to the Clinic of Optic Neuritis had symptoms caused by medical, neurosurgical or ophthalmic disorders, and 0.9 % of our patients had NMO. Though most of these conditions are rare, it is of importance to keep them in mind upon encountering patients with symptoms of ON. [ABSTRACT FROM AUTHOR]

Objective: Optic neuritis (ON) is an autoimmune acute demyelinating disease of the optic nerve and may occur in patients with confirmed multiple sclerosis (MS) or as a clinically isolated syndrome. T lymphocytes play a central role in the pathogenesis of MS. The phenotype of different T cell subsets is usually characterized by the expression of distinct cell surface receptors such as CD45RA, CD45RO, CCR7, CD27 and CD28. The aim of this study was to characterize the phenotype of distinct subsets of CD4 and CD8 T cells in patients with isolated ON. Methods: CD4 and CD8 T cell subsets were characterized by flow cytometry in fresh peripheral blood and cerebrospinal fluid (CSF) samples using the surface markers CD27, CD25, CD45RA, CD45RO and intracellular FOXP3. The T cell subsets expressed in patients with acute ON (n = 64; symptom onset of ON within the preceding 28 days) were compared to those of a gender- and age-matched healthy control (HC) group (n = 32). Results: Both CD4+ and CD8+ naïve T cells in the ON group were significantly reduced in the CSF. In contrast, most of the intermediate-stage and late effector CD4+ and CD8+ T cell subsets as well as the CD4+ T regulatory cells were expressed in ON patients, though not at all in the CSF of the HC group. Conclusion: These results add important evidence for inflammatory and regulatory activity in ON and early MS. Copyright © 2012 S. Karger AG, Basel [ABSTRACT FROM AUTHOR]

Background: In recent years, small-scale clinical trials have indicated that statins or 3-hydroxy-3-methylglutaryl coenzyme A (HMGCoA) reductase inhibitors exert pleiotropic immunomodulatory effects, with potential therapeutic implications in multiple sclerosis (MS).Objective: To investigate whether simvastatin treatment (80 mg daily for 6 months) in patients with optic neuritis (ON) had a beneficial effect on visual outcome and on brain MRI.Methods: Sixty-four patients with acute ON were randomized to simvastatin treatment (n = 32) or placebo (n = 32) for 6 months. None of the patients had been on immunosuppressive therapy for 6 months prior to inclusion or treated with steroids from symptom onset. Contrast sensitivity (Arden plates), visual acuity, colour perception, visual evoked potentials (VEP) – latency and amplitude, Visual Analogue Scale (VAS) score, and gadolinium enhancing and T2 lesions on brain MRI were evaluated at screening visit, day 14 (except brain MRI), day 90 and day 180.Results: Simvastatin had a beneficial effect on VEP in both latency (p = 0.01) and amplitude (p = 0.01), a borderline effect on the Arden score (p = 0.06) and VAS (p = 0.04), and no effect on brain MRI or on relapse rate between the groups.Conclusion: This study provides Class I evidence that simvastatin 80 mg daily is well tolerated and possibly effective in patients with acute ON. [ABSTRACT FROM AUTHOR]

Background: Acute monosymptomatic optic neuritis (ON) may be the earliest manifestation of multiple sclerosis (MS). Atrophy has been shown to be a prominent feature of MS with great impact on disability.Objectives: The objectives of this study were to evaluate retinal and brain atrophy and possible associations at the earliest possible stages of MS.Methods: In a prospective observational cohort study we included 60 untreated patients with monosymptomatic ON and 19 healthy volunteers. Unaffected fellow eyes were examined with optical coherence tomography (OCT) and normalized brain volumes were calculated based on MRI. Additionally, visual evoked potentials (VEPs) were recorded.Results: Neither OCT measurements nor brain volume measures revealed signs of localized or generalized atrophy in patients compared with healthy volunteers. Stratification of patients into high risk based on the presence of white matter lesions did not reveal differences. The association between OCT measures and brain volumes previously found could not be confirmed at the time of the first clinical event. VEP latency was significantly prolonged in patients with white matter lesions compared to those without lesions. A trend towards a relationship between VEP amplitude of fellow eyes and brain volumes was noted.Conclusions: In this cohort we were not able to show atrophic features in the retina or the brain, and the association between structural measures of the retina and the brain as indicated in the later stages of MS could not be reproduced. These findings suggest that atrophy does require time to evolve and indicate the complexity of the relationship between local and general structural measures. [ABSTRACT FROM AUTHOR]

A response from the author of the article "Simvastatin improves final visual outcome in acute optic neuritis, a randomized study" in the January 2012 issue is presented.