Cardiac and respiratory dysfunction in Duchenne muscular dystrophy and the role of second messengers.

Duchenne muscular dystrophy (DMD) affects young boys and is characterized by the absence of dystrophin, a large cytoskeletal protein present in skeletal and cardiac muscle cells and neurons. The heart and diaphragm become necrotic in DMD patients and animal models of DMD, resulting in cardiorespiratory failure as the leading cause of death. The major consequences of the absence of dystrophin are high levels of intracellular Ca(2+) and the unbalanced production of NO that can finally trigger protein degradation and cell death.

Expression profiling reveals novel hypoxic biomarkers in peripheral blood of adult mice exposed to chronic hypoxia.

Hypoxia induces a myriad of changes including an increase in hematocrit due to erythropoietin (EPO) mediated erythropoiesis. While hypoxia is of importance physiologically and clinically, lacunae exist in our knowledge of the systemic and temporal changes in gene expression occurring in blood during the exposure and recovery from hypoxia. To identify these changes expression profiling was conducted on blood obtained from cohorts of C57Bl-10 wild type mice that were maintained at normoxia (NX), exposed for two weeks to normobaric chronic hypoxia (CH) or two weeks of CH followed by two weeks of normoxic recovery (REC).

Superior calcium homeostasis of extraocular muscles.

Extraocular muscles (EOMs) are a unique group of skeletal muscles with unusual physiological properties such as being able to undergo rapid twitch contractions over extended periods and escape damage in the presence of excess intracellular calcium (Ca(2+)) in Duchenne's muscular dystrophy (DMD). Enhanced Ca(2+) buffering has been proposed as a contributory mechanism to explain these properties; however, the mechanisms are not well understood. We investigated mechanisms modulating Ca(2+) levels in EOM and tibialis anterior (TA) limb muscles.

Identification of the neuromuscular junction transcriptome of extraocular muscle by laser capture microdissection.

Purpose: To examine and characterize the profile of genes expressed at the synapses or neuromuscular junctions (NMJs) of extraocular muscles (EOMs) compared with those expressed at the tibialis anterior (TA).

Methods: Adult rat eyeballs with rectus EOMs attached and TAs were dissected, snap frozen, serially sectioned, and stained for acetylcholinesterase (AChE) to identify the NMJs. Approximately 6000 NMJs for rectus EOM (EOMsyn), 6000 NMJs for TA (TAsyn), equal amounts of NMJ-free fiber regions (EOMfib, TAfib), and underlying myonuclei and RNAs were captured by laser capture microdissection (LCM).

Distinctive patterns of microRNA expression in extraocular muscles.

The extraocular muscles (EOMs) are a unique group of muscles that are anatomically and physiologically distinct from other muscles. We and others have shown that EOMs have a unique transcriptome and proteome. Here we investigated the expression pattern of microRNAs (miRNAs), as they may play a role in generating the unique EOM allotype.

Transcriptional and functional differences in stem cell populations isolated from extraocular and limb muscles.

The extraocular muscles (EOMs) are a distinct muscle group that displays an array of unique contractile, structural, and regenerative properties. They also have differential sensitivity to certain diseases and are enigmatically spared in Duchenne muscular dystrophy (DMD). The EOMs are so distinct from other skeletal muscles that the term "allotype" has been coined to highlight EOM group-specific properties.

Comparison of the myoplasmic calcium transient elicited by an action potential in intact fibres of mdx and normal mice.

The myoplasmic free [Ca2+] transient elicited by an action potential (Delta[Ca2+]) was compared in fast-twitch fibres of mdx (dystrophin null) and normal mice. Methods were used that maximized the likelihood that any detected differences apply in vivo. Small bundles of fibres were manually dissected from extensor digitorum longus muscles of 7- to 14-week-old mice.

Combination of peptide OFFGEL fractionation and label-free quantitation facilitated proteomics profiling of extraocular muscle.

Several label-free quantitation strategies have been introduced that obliterate the need for expensive isotopically labeled molecules. However label-free approaches have considerably higher demands in respect of repeatability of sample preparation and fractionation than multiplexing isotope labeling-based strategies. OFFGEL fractionation promises the necessary separation efficiency and repeatability.

Quantitative proteomics profiling of sarcomere associated proteins in limb and extraocular muscle allotypes.

The sarcomere is the major structural and functional unit of striated muscle. Approximately 65 different proteins have been associated with the sarcomere, and their exact composition defines the speed, endurance, and biology of each individual muscle. Past analyses relied heavily on electrophoretic and immunohistochemical techniques, which only allow the analysis of a small fraction of proteins at a time.