David Ellenberger

Ca2+/Calmodulin-Dependent Protein Kinase II and Protein Kinase A Differentially Regulate Sarcoplasmic Reticulum Ca2+ Leak in Human Cardiac Pathology

Background —Sarcoplasmatic reticulum (SR) Ca2+-leak through ryanodine receptor type 2 (RyR2) dysfunction is of major pathophysiological relevance in human heart failure (HF). However, mechanisms underlying progressive RyR2 dysregulation from cardiac hypertrophy (Hy) to HF are still controversial. Methods and Results —We investigated healthy control myocardium (NF, n=5) as well as myocardium from patients with compensated Hy (n=25) and HF (n=32). In Hy, Ca2+/calmodulin-dependent protein kinase II (CaMKII) and protein kinase A (PKA) both phosphorylate RyR2 at levels which are not different from NF. Accordingly, inhibitors of these kinases reduce the SR Ca2+-leak. In HF, however, the SR Ca2+-leak is nearly doubled compared to Hy leading to reduced systolic Ca2+-transients, a depletion of SR Ca2+-storage and elevated diastolic Ca2+-levels. This is accompanied by a significantly increased CaMKII-dependent phosphorylation of RyR2. In contrast, PKA-dependent RyR2 phosphorylation is not increased in HF and is independent of previous β-blocker treatment. In HF CaMKII inhibition but not inhibition of PKA yields a reduction of the SR Ca2+-leak. Moreover, PKA inhibition further reduces SR Ca2+-load and systolic Ca2+-transients. Conclusions —In human Hy CaMKII as well as PKA functionally regulate RyR2 and may induce SR Ca2+-leak. In the transition from Hy to HF the diastolic Ca2+-leak increases and disturbed Ca2+-cycling occurs. This is associated with an increase in CaMKII- but not PKA-dependent RyR2-phosphorylation. CaMKII inhibition may thus reflect a promising therapeutic target for the treatment of arrhythmias and contractile dysfunction.Background— Sarcoplasmic reticulum (SR) Ca2+ leak through ryanodine receptor type 2 (RyR2) dysfunction is of major pathophysiological relevance in human heart failure (HF); however, mechanisms underlying progressive RyR2 dysregulation from cardiac hypertrophy to HF are still controversial. Methods and Results— We investigated healthy control myocardium (n=5) and myocardium from patients with compensated hypertrophy (n=25) and HF (n=32). In hypertrophy, Ca2+/calmodulin-dependent protein kinase II (CaMKII) and protein kinase A (PKA) both phosphorylated RyR2 at levels that were not different from healthy myocardium. Accordingly, inhibitors of these kinases reduced the SR Ca2+ leak. In HF, however, the SR Ca2+ leak was nearly doubled compared with hypertrophy, which led to reduced systolic Ca2+ transients, a depletion of SR Ca2+ storage and elevated diastolic Ca2+ levels. This was accompanied by a significantly increased CaMKII-dependent phosphorylation of RyR2. In contrast, PKA-dependent RyR2 phosphorylation was not increased in HF and was independent of previous &bgr;-blocker treatment. In HF, CaMKII inhibition but not inhibition of PKA yielded a reduction of the SR Ca2+ leak. Moreover, PKA inhibition further reduced SR Ca2+ load and systolic Ca2+ transients. Conclusions— In human hypertrophy, both CaMKII and PKA functionally regulate RyR2 and may induce SR Ca2+ leak. In the transition from hypertrophy to HF, the diastolic Ca2+ leak increases and disturbed Ca2+ cycling occurs. This is associated with an increase in CaMKII- but not PKA-dependent RyR2 phosphorylation. CaMKII inhibition may thus reflect a promising therapeutic target for the treatment of arrhythmias and contractile dysfunction.

CaMKII and PKA Differentially Regulate SR Ca2+-Leak in Human Cardiac Pathology

Background —Sarcoplasmatic reticulum (SR) Ca2+-leak through ryanodine receptor type 2 (RyR2) dysfunction is of major pathophysiological relevance in human heart failure (HF). However, mechanisms underlying progressive RyR2 dysregulation from cardiac hypertrophy (Hy) to HF are still controversial. Methods and Results —We investigated healthy control myocardium (NF, n=5) as well as myocardium from patients with compensated Hy (n=25) and HF (n=32). In Hy, Ca2+/calmodulin-dependent protein kinase II (CaMKII) and protein kinase A (PKA) both phosphorylate RyR2 at levels which are not different from NF. Accordingly, inhibitors of these kinases reduce the SR Ca2+-leak. In HF, however, the SR Ca2+-leak is nearly doubled compared to Hy leading to reduced systolic Ca2+-transients, a depletion of SR Ca2+-storage and elevated diastolic Ca2+-levels. This is accompanied by a significantly increased CaMKII-dependent phosphorylation of RyR2. In contrast, PKA-dependent RyR2 phosphorylation is not increased in HF and is independent of previous β-blocker treatment. In HF CaMKII inhibition but not inhibition of PKA yields a reduction of the SR Ca2+-leak. Moreover, PKA inhibition further reduces SR Ca2+-load and systolic Ca2+-transients. Conclusions —In human Hy CaMKII as well as PKA functionally regulate RyR2 and may induce SR Ca2+-leak. In the transition from Hy to HF the diastolic Ca2+-leak increases and disturbed Ca2+-cycling occurs. This is associated with an increase in CaMKII- but not PKA-dependent RyR2-phosphorylation. CaMKII inhibition may thus reflect a promising therapeutic target for the treatment of arrhythmias and contractile dysfunction.Background— Sarcoplasmic reticulum (SR) Ca2+ leak through ryanodine receptor type 2 (RyR2) dysfunction is of major pathophysiological relevance in human heart failure (HF); however, mechanisms underlying progressive RyR2 dysregulation from cardiac hypertrophy to HF are still controversial. Methods and Results— We investigated healthy control myocardium (n=5) and myocardium from patients with compensated hypertrophy (n=25) and HF (n=32). In hypertrophy, Ca2+/calmodulin-dependent protein kinase II (CaMKII) and protein kinase A (PKA) both phosphorylated RyR2 at levels that were not different from healthy myocardium. Accordingly, inhibitors of these kinases reduced the SR Ca2+ leak. In HF, however, the SR Ca2+ leak was nearly doubled compared with hypertrophy, which led to reduced systolic Ca2+ transients, a depletion of SR Ca2+ storage and elevated diastolic Ca2+ levels. This was accompanied by a significantly increased CaMKII-dependent phosphorylation of RyR2. In contrast, PKA-dependent RyR2 phosphorylation was not increased in HF and was independent of previous &bgr;-blocker treatment. In HF, CaMKII inhibition but not inhibition of PKA yielded a reduction of the SR Ca2+ leak. Moreover, PKA inhibition further reduced SR Ca2+ load and systolic Ca2+ transients. Conclusions— In human hypertrophy, both CaMKII and PKA functionally regulate RyR2 and may induce SR Ca2+ leak. In the transition from hypertrophy to HF, the diastolic Ca2+ leak increases and disturbed Ca2+ cycling occurs. This is associated with an increase in CaMKII- but not PKA-dependent RyR2 phosphorylation. CaMKII inhibition may thus reflect a promising therapeutic target for the treatment of arrhythmias and contractile dysfunction.

Clinical presentation of pediatric multiple sclerosis before puberty

Multiple sclerosis (MS) onset before puberty is extremely rare and establishment of diagnosis is often difficult due to atypical presentation. The study aims to identify the typical presentation of MS in this age group.

Multiple sclerosis registries in Europe – results of a systematic survey

Background: Identification of MS registries and databases that are currently in use in Europe as well as a detailed knowledge of their content and structure is important in order to facilitate comprehensive analysis and comparison of data. Methods: National MS registries or databases were identified by literature search, from the results of the MS Barometer 2011 and by asking 33 national MS societies. A standardized questionnaire was developed and sent to the registries’ leaders, followed by telephone interviews with them. Results: Twenty registries were identified, with 13 completing the questionnaire and seven being interviewed by telephone. These registries differed widely for objectives, structure, collected data, and for patients and centres included. Despite this heterogeneity, common objectives of the registries were epidemiology (n=10), long-term therapy outcome (n=8), healthcare research (n=9) and support/basis for clinical trials (n=8). While physician-based outcome measures (EDSS) are used in all registries, data from patients’ perspectives were only collected in six registries. Conclusions: The detailed information on a large number of national MS registries in Europe is a prerequisite to facilitating harmonized integration of existing data from MS registries and databases, as well as comprehensive analyses and comparison across European populations.

Serum peptide reactivities may distinguish neuromyelitis optica subgroups and multiple sclerosis

Objective: To assess in an observational study whether serum peptide antibody reactivities may distinguish aquaporin-4 (AQP4) antibody (Ab)–positive and -negative neuromyelitis optica spectrum disorders (NMOSD) and relapsing-remitting multiple sclerosis (RRMS). Methods: We screened 8,700 peptides that included human and viral antigens of potential relevance for inflammatory demyelinating diseases and random peptides with pooled sera from different patient groups and healthy controls to set up a customized microarray with 700 peptides. With this microarray, we tested sera from 66 patients with AQP4-Ab-positive (n = 16) and AQP4-Ab-negative (n = 19) NMOSD, RRMS (n = 11), and healthy controls (n = 20). Results: Differential peptide reactivities distinguished NMOSD subgroups from RRMS in 80% of patients. However, the 2 NMOSD subgroups were not well-discriminated, although those patients are clearly separated by their antibody reactivities against AQP4 in cell-based assays. Elevated reactivities to myelin and Epstein-Barr virus peptides were present in RRMS and to AQP4 and AQP1 peptides in AQP4-Ab-positive NMOSD. Conclusions: While AQP4-Ab-positive and -negative NMOSD subgroups are not well-discriminated by peptide antibody reactivities, our findings suggest that peptide antibody reactivities may have the potential to distinguish between both NMOSD subgroups and MS. Future studies should thus concentrate on evaluating peptide antibody reactivities for the differentiation of AQP4-Ab-negative NMOSD and MS.

Therapeutic Apheresis in Pediatric Patients with Acute CNS Inflammatory Demyelinating Disease

Background/Aims: In adults, plasma exchange (PE) has been shown to be an efficient treatment for severe relapses of acute inflammatory CNS demyelinating diseases. The aim of this study was to evaluate the safety and efficacy of this treatment in pediatric patients. Methods: We retrospectively analyzed a single-center cohort of pediatric patients with inflammatory CNS demyelinating disorders who underwent apheresis between 2007 and 2011. Results: Ten patients (mean age: 11.6 ± 3.4 years) with an acute relapse of multiple sclerosis (n = 5), neuromyelitis optica (n = 2) or acute disseminated encephalomyelitis were included. All received methylprednisolone prior to treatment with either PE (n = 5) or immunoadsorption (n = 5). Apheresis-related side effects were either self-limiting or easily managed. EDSS (Expanded Disability Status Scale) improved in 7 of 8 patients during apheresis and in all patients within 30 days from a median of 7.5 to 1 (p < 0.01). The visual acuity initially worsened during the procedure in 3 of 7 affected eyes (mean 0.09), but improved in all at follow-up (mean: 0.5; p = 0.008). Conclusions: Apheresis was well tolerated and associated with a favorable outcome in all pediatric patients similar to reports in adults.

JC virus antibody status in a pediatric multiple sclerosis cohort: Prevalence, conversion rate and influence on disease severity

Background: Because of the emergence of novel therapies for multiple sclerosis (MS) and the associated increased risk of progressive multifocal leukoencephalopathy, John Cunningham (JC) virus infection has become a focus of interest for neurologists. However, little is known about JC virus infection in pediatric MS to date. Objective: We aimed to analyze the prevalence of anti-JC virus antibodies, the conversion rate and the influence of the anti-JC virus antibody status on the clinical course in a large pediatric MS cohort. Methods: Anti-JC virus antibodies were analyzed in serum samples within six months of disease onset and during the course of the disease. Clinical data were extracted from a pediatric MS databank. Results: A total of 51.6% of 256 patients were found to be positive for anti-JC virus antibodies at onset of disease. No correlation between antibody status and clinical course was seen. Analyzing 693 follow-up serum samples revealed high titer stability, and an annual conversion rate of 4.37% was seen. Conclusion: No evidence was found that seropositivity for anti-JC virus antibodies influences the clinical course. Surprisingly, seroprevalence for anti-JC virus antibodies was more than twice as high as anticipated in this age group, raising the question of whether the infection increases the risk of MS development.

Patients characteristics influencing the longitudinal utilization of steroids in multiple sclerosis--an observational study.

Multiple Sclerosis is the most common disease in young adults affecting the central nervous system. Disease may progress with acute attacks (relapsing MS) or continuously (progressive MS). Glucocorticosteroids are used in the treatment of acute attacks. The aim of this study was to analyse characteristics of patients with MS, and their influence on current treatment patterns of relapses with glucocorticosteroids.

Tumor genetics and survival of thymic neuroendocrine neoplasms: A multi‐institutional clinicopathologic study

Thymic neuroendocrine tumors (TNET) are rare primary epithelial neoplasms of the thymus. This study aimed to determine clinically relevant parameters for their classification and for therapeutic decisions. We performed a comprehensive histological, clinical, and genetic study of 73 TNET cases (13 thymic typical carcinoids [TTC], 40 thymic atypical carcinoids [TAC], and 20 high‐grade neuroendocrine carcinomas [HGNEC] of the thymus), contributed by multiple institutions. The mean number of chromosomal imbalances per tumor was 0.8 in TTC (31% aberrant cases) versus 1.1 in TAC (44% aberrant cases) versus 4.7 in HGNEC (75% aberrant cases). Gains of 8q24 (MYC gene locus) were the most frequent alteration and one of the overlapping features between carcinoids and HGNEC. The 5‐year survival rates for TTC, TAC, and HGNEC were 100, 60, and 30%. The 10‐year survival rates for TTC and TAC were 50 and 30% (P = 0.002). Predictive mitotic cut‐off values for TTC versus TAC were 2.5 per 10 high‐power fields (HPF; indicating a higher death rate, P = 0.062) and 15 per 10 HPF (indicating higher risk of recurrence, P = 0.036) for separating HGNEC from TAC. We conclude that the current histopathologic classifications of TNET reflect tumor biology and provide important information for therapeutic management.

Analysis of high-dimensional one group repeated measures designs

We propose a novel one sample test for repeated measures designs and derive its limit distribution for the situation where both the sample size n as well as the dimension d of the observations go to infinity. This covers the high-dimensional case with . The tests are based on a quadratic form which involve new unbiased and dimension-stable estimators of different traces of the underlying unrestricted covariance structure. It is shown that the asymptotic distribution of the statistic may be standard normal, standardized -distributed, or even of weighted -form in some situations. To this end, we suggest an approximation technique which is asymptotically valid in the first two cases and provides an accurate approximation for the latter. We motivate and illustrate the application with a sleep lab data set and also discuss the practical meaning of in case of repeated measures designs. It turns out that the limit behaviour depends on how the number of repeated measures is increased which is crucial for application.