The effects of rise/fall time and plateau time on ocular vestibular evoked myogenic potentials.

Ocular vestibular evoked myogenic potentials (oVEMP) are strongly influenced by recording conditions and stimulus parameters. Throughout the published literature, a large variety of stimuli is used for eliciting oVEMP. Our objective was to determine the effects of different rise/fall times and plateau times on oVEMP amplitudes and latencies. 32 healthy subjects were enrolled in the study. 500 Hz air-conducted tone bursts with the parameters rise-plateau-fall time 0-4-0, 4-0-4, 2-2-2 and 2-4-2 ms were used for eliciting oVEMP. For all stimuli, response prevalences were 100 %. The 4-0-4 ms stimulus generated the smallest amplitudes, whereas the 2-2-2 and 0-4-0 ms stimuli achieved the largest amplitudes. n1 and p1 latencies were significantly shorter for the 0-4-0 ms than for the other stimuli, whereas latencies in response to the 4-0-4 ms stimulus were prolonged. Hence, a variety of stimuli is suitable for evoking oVEMP in healthy subjects. We recommend a 2-2-2 ms stimulus for clinical testing of oVEMP elicited by air conducted sound, because it reproducibly generates oVEMP without exposing the ear to unnecessary amounts of acoustic energy.

Endolymphatic hydrops in patients with vestibular migraine and auditory symptoms.

Vertigo patients exhibiting features of vestibular migraine (VM) and Menière's disease (MD) present a difficult diagnostic challenge to the clinician, and the two entities are likely to overlap. The aim of the present study was to investigate the occurrence of endolymphatic hydrops in patients with VM and auditory symptoms. This was an observatory diagnostic study. At an academic interdisciplinary dizziness centre, nineteen consecutive patients with definite or probable VM and auditory symptoms were examined by locally enhanced inner ear MR imaging. MR images were evaluated for the presence of endolymphatic hydrops. Of the 19 included patients, four patients (21 %) demonstrated evidence of cochlear and vestibular endolymphatic hydrops on locally enhanced inner ear MR imaging (three with "definite VM", one with "probable VM"). Locally enhanced inner ear MR imaging may be useful in the diagnostic evaluation of patients with VM and auditory symptoms, as some of these patients have signs of endolymphatic hydrops. Whether these patients suffer from MD only and are misdiagnosed as VM or suffer from both, VM and MD or whether endolymphatic hydrops is a consequence of inner ear damage due to VM are clinically relevant questions that can be evaluated by application of this technique.

The effects of commonly used upward gaze angles on ocular vestibular evoked myogenic potentials.

OBJECTIVE: Ocular vestibular evoked myogenic potentials (oVEMP) represent extraocular muscle activity in response to vestibular stimulation. oVEMP amplitudes are known to be modulated by gaze elevation. However, it is not well known to which extent oVEMP are modulated by upward gaze. We thus investigated the effects of commonly used upward gaze angles on oVEMP amplitudes and latencies. STUDY DESIGN: Prospective study. SETTING: Tertiary referral center for vestibular disorders. SUBJECTS: Thirty-two healthy subjects were enrolled in this study. INTERVENTIONS: 500 Hz air-conducted tone bursts were used to elicit oVEMP with the subject maintaining 30 and 35 degrees and maximal upward gaze, respectively. MAIN OUTCOME MEASURES: Amplitudes and latencies of oVEMP responses. RESULTS: n1-p1 amplitudes significantly increased with increasing gaze angle from 30 to 35 degrees. Maximal up-gaze, however, did not result in further enlargement of amplitudes. Latencies were not affected by gaze elevation. CONCLUSION: A small increase in upward gaze angle caused a considerable augmentation of amplitudes. Controlling the level of gaze when recording oVEMP is thus indispensable to ensure interindividual and intraindividual comparability of oVEMP results.

Recombinant chaperonin 10 suppresses cutaneous lupus and lupus nephritis in MRL-(Fas)lpr mice.

BACKGROUND: Systemic lupus erythematosus (SLE) is still treated with global immunosuppressants with serious toxicities. We hypothesized that endogenous immunosuppressive molecules might be able to control SLE manifestations more specifically. Heat shock protein 10, or chaperonin 10 (Cpn10), is a secretory molecule that can suppress innate and adaptive immunity. METHODS: Recombinant human Cpn10 (100 µg per mouse) was given intraperitoneally to healthy-appearing female MRL-(Fas)lpr mice from 12 to 22 weeks of age. At the age of 22 weeks, mice were analysed for treatment outcome by harvesting organs, plasma and urine. RESULTS: Cpn10 entirely prevented cutaneous lupus lesions as compared to vehicle-treated mice. Cpn10 also suppressed lupus nephritis as evident from serum creatinine levels, albuminuria and the scores of disease activity and chronicity. Autoimmune lung disease was unaffected by Cpn10 treatment while overall survival of mice was prolonged. Cpn10 did not have any major effects on either dendritic cell or B-cell counts except T cells in spleen, plasma interferon-gamma, tumour necrosis factor-alpha, interleukin-10, anti-nuclear autoantibody levels or markers of lymphoproliferation. CONCLUSIONS: In summary, recombinant Cpn10 selectively prevents cutaneous lupus and suppresses nephritis in MRL-(Fas)lpr mice without affecting the underlying systemic autoimmune process. Hence, Cpn10 might be useful for the treatment of skin and kidney manifestations of SLE.

Interleukin-1 receptor-associated kinase-M suppresses systemic lupus erythematosus.

OBJECTIVES: Interleukin-1 receptor-associated kinase (IRAK)-M suppresses Toll-like receptor (TLR)-mediated activation of innate immunity during infection. A similar role was hypothesised for IRAK-M in autoimmunity. METHODS: Irak-m-deficient mice were crossed with autoimmune C57BL/6-lpr/lpr mice and detailed phenotype analysis was performed. RESULTS: Irak-m deficiency converted the mild autoimmune phenotype of C57BL/6-lpr/lpr mice into a massive lymphoproliferative syndrome with lethal autoimmune lung disease and lupus nephritis. Irak-m deficiency induced a number of interferon-related genes, cytokines and plasma cell survival factors in spleen cells of these mice. Irak-m-deficient C57BL/6-lpr/lpr mice showed expansion of autoreactive T cells, dysfunctional regulatory T cells and plasma cells which was associated with increased lupus autoantibody production. TLR7 antagonism almost completely abrogated this phenotype consistent with IRAK-M-mediated suppression of TLR7 signalling in vitro. CONCLUSIONS: These data identify a previously unknown function of IRAK-M-namely, suppression of TLR7-mediated autoimmunity-and mutant IRAK-M as a previously unknown genetic risk for murine SLE.

4SC-101, a novel small molecule dihydroorotate dehydrogenase inhibitor, suppresses systemic lupus erythematosus in MRL-(Fas)lpr mice.

Immunosuppressive treatments of systemic lupus (SLE) remain associated with significant toxicities; hence, compounds with better toxicity profiles are needed. Dihydroorotate dehydrogenase (DHODH) inhibition with leflunomide has proven to be effective in autoimmune diseases including SLE, but leflunomide can cause a variety of side effects. We hypothesized that 4SC-101, a novel DHODH inhibitor with a more favorable toxicity profile, would be as effective as high-dose cyclophosphamide (CYC) in controlling experimental SLE of female MRL(Fas)lpr mice. Daily oral gavage of 30, 100, and 300 mg/kg 4SC-101 from 12 to 22 weeks of age was compared with either vehicle or CYC treatment (30 mg/kg/week, i.p.) in terms of efficacy and toxicity. Three hundred milligrams per kilogram 4SC-101 was as effective as CYC in depleting spleen autoreactive T cells, B cells, and plasma cells as well as the respective DNA and RNA serum autoantibodies. This was associated with a comparable amelioration of the renal, dermal, and pulmonary SLE manifestations of MRL(Fas)lpr mice. However, even the highest dose of 4SC-101 had no effect on bone marrow neutrophil counts, which were significantly reduced in CYC-treated mice. Together, the novel DHODH inhibitor 4SC-101 is as effective as high dose CYC in controlling SLE without causing myelosuppression. Hence, DHODH inhibition with 4SC-101 might be suitable to treat active SLE with fewer side effects than CYC.