Studies of myocardial metabolism using P-31-NMR spectroscopy and a simple heart perfusion model of slaughtered animals--an approach to avoiding in vivo animal experiments

In research cardiology large numbers of in vivo animal experiments, mostly with dogs or pigs, are necessary. It was the aim of this study to test a simple in vitro perfusion heart model from swine harvested in the slaughterhouse as a potential substitute for in vivo animal studies. 32 unselected hearts of slaughterhouse swine after 10 to 15 min of warm ischemia were subjected to reperfusion with warm oxygenized blood and were examined for mechanical recovery, which occurred in 56%, increasing to 95% if primarily using only hearts that were in relaxation. In 21 of selected relaxed heart models the energy phosphate pattern as an index of viability was measured by P-31 MRS on a 4.7 Tesla NMR tomograph in 37 experimental runs with the following perfusion protocols: 1) immediate cardioplegia with cold Bretschneider or Collins solution, transportation under cooling, MRS after approximately 1 h; 2) immediate cardioplegia, transportation, reperfusion with oxygenated warm blood, MRS; 3) immediate blood perfusion with genuine fresh arterial blood from the slaughterhouse, cold plegia perfusion, transportation, MRS; 4) immediate blood perfusion with transportation MRS; 4) immediate blood perfusion with genuinefresh arterial blood, cold plegia perfusion, transportation, reperfusion with oxygenated warm blood, MRS during reperfusion; 5) An experimental pig heart was made plegic in vivo and reperfused with oxygenated warm blood during MRS as reference.(ABSTRACT TRUNCATED AT 250 WORDS)     

RNA Foci, CUGBP1, and ZNF9 are the primary targets of the mutant CUG and CCUG repeats expanded in myotonic dystrophies type 1 and type 2

Expansions of noncoding CUG and CCUG repeats in myotonic dystrophies type 1 (DM1) and DM2 cause complex molecular pathology, the features of which include accumulation of RNA aggregates and misregulation of the RNA-binding proteins muscleblind-like 1 (MBNL1) and CUG-binding protein 1 (CUGBP1). CCUG repeats also decrease amounts of the nucleic acid binding protein ZNF9. Using tetracycline (Tet)-regulated monoclonal cell models that express CUG and CCUG repeats, we found that low levels of long CUG and CCUG repeats result in nuclear and cytoplasmic RNA aggregation with a simultaneous increase of CUGBP1 and a reduction of ZNF9. Elevation of CUGBP1 and reduction of ZNF9 were also observed before strong aggregation of the mutant CUG/CCUG repeats. Degradation of CUG and CCUG repeats normalizes ZNF9 and CUGBP1 levels. Comparison of short and long CUG and CCUG RNAs showed that great expression of short repeats form foci and alter CUGBP1 and ZNF9; however, long CUG/CCUG repeats misregulate CUGBP1 and ZNF9 much faster than high levels of the short repeats. These data suggest that correction of DM1 and DM2 might be achieved by complete and efficient degradation of CUG and CCUG repeats or by a simultaneous disruption of CUG/CCUG foci and correction of CUGBP1 and ZNF9.     

Reducing body myopathy and other FHL1-related muscular disorders

During the past 2 years, considerable progress in the field of four and a half LIM domain protein 1 (FHL1)-related myopathies has led to the identification of a growing number of FHL1 mutations. This genetic progress has uncovered crucial pathophysiological concepts, thus redefining clinical phenotypes. Important new characterizations include 4 distinct human myopathies: reducing body myopathy, X-linked myopathy with postural muscle atrophy, Emery-Dreifuss muscular dystrophy, and scapuloperoneal myopathy. Additionally, FHL1 mutations have been discovered in rigid spine syndrome and in a single family with contractures, rigid spine, and cardiomyopathy. In this review, we focus on the clinical phenotypes, which we correlate with the novel genetic and histological findings encountered within FHL1-related myopathies. This correlation will frequently lead to a considerably expanded clinical spectrum associated with a given FHL1 mutation.     

Nemaline myopathy caused by mutations in the nebulin gene may present as a distal myopathy

Mutations in the nebulin gene are the main cause of autosomal recessive nemaline myopathy, with clinical presentations ranging from mild to severe disease. We have previously reported a nonspecific distal myopathy caused by homozygous missense mutations in the nebulin gene in six Finnish patients from four different families. Here we describe three non-Finnish patients in two unrelated families with distal nemaline myopathy caused by four different compound heterozygous nebulin mutations, only one of which is a missense mutation. One of the mutations has previously been identified in one family with the severe form of nemaline myopathy. We conclude that nemaline myopathy and distal myopathy caused by nebulin mutations form a clinical and histological continuum. Nemaline myopathy should be considered as a differential diagnosis in patients presenting with an early-onset predominantly distal myopathy.     

Myofibrillar Myopathies: A Clinical and Myopathological Guide

Myofibrillar myopathies (MFMs) are histopathologically characterized by desmin-positive protein aggregates and myofibrillar degeneration. Because of the marked phenotypic and pathomorphological variability, establishing the diagnosis of MFM can be a challenging task. While MFMs are partly caused by mutations in genes encoding for extramyofibrillar proteins (desmin, αB-crystallin, plectin) or myofibrillar proteins (myotilin, Z-band alternatively spliced PDZ-containing protein, filamin C, Bcl-2-associated athanogene-3, four-and-a-half LIM domain 1), a large number of these diseases are caused by still unresolved gene defects. Although recent years have brought new insight into the pathogenesis of MFMs, the precise molecular pathways and sequential steps that lead from an individual gene defect to progressive muscle damage are still unclear. This review focuses on the clinical and myopathological aspects of genetically defined MFMs, and shall provide a diagnostic guide for this numerically significant group of protein aggregate myopathies.     

Soluble guanylyl cyclase is localized at the neuromuscular junction in human skeletal muscle

Soluble guanlylyl cyclase (sGC) seems to be involved in mechanisms for rapid translation of electrical and chemical signals at the neuromuscular junction. To explore the cellular localization of the alpha2, alpha1 and beta1 subunits of sGC, we studied normal and denervated human muscle biopsies immunohistochemically using antibodies directed against the alpha2 and alpha1/beta1 subunits of sGC and performed double labellings with alpha-bungarotoxin. Confocal imaging could localize the alpha2 and alpha1/beta1 subunits of sGC at neuromuscular junctions and vessels and the subunits remained concentrated at neuromuscular junctions following denervation. The presence of sGC at neuromuscular junctions and at vessels suggests sGC could serve as a postsynaptic second messenger for fine tuning of nerve-muscle interaction and dynamic regulation of intramuscular blood flow.     

Evoked potentials during active horizontal head rotations in patients with vertigo

OBJECTIVES: The purpose of this study was to investigate whether evoked potentials by active head rotation help to verify and topographically differentiate patients with the major symptom vertigo.METHODS: Twenty-four healthy human subjects and 43 patients with either infratentorial or supratentorial brain lesions were analysed.RESULTS: The evoked response in normal subjects was composed of six peaks, indicated by polarization and time difference from the trigger points P100, N30, P0, N50, P155 and N320. The EEG pattern was independent of the direction, type of target and whether the eyes were open or closed. In contrast, the evoked response, especially P155, was dependent on the chosen trigger point and acceleration. P155 was the most stable and significant component of the evoked potentials. Thus, we chose P155 as the reference for studying patients with vertigo.DISCUSSION: In peripheral vestibular disorders, cerebellar and diffuse supratentorial cerebral lesions and P155 latencies remain non-significantly altered. However, P155 latencies significantly increase in pontine lesions homolaterally, and space occupying tumors contralaterally.CONCLUSION: Active horizontal head rotations differentially stimulate the vestibulocortical pathways and may contribute to the analysis of vertigo.