Localization of multiple neurotransmitters in surgically derived specimens of human atrial ganglia.

Dysfunction of the intrinsic cardiac nervous system is implicated in the genesis of atrial and ventricular arrhythmias. While this system has been studied extensively in animal models, far less is known about the intrinsic cardiac nervous system of humans. This study was initiated to anatomically identify neurotransmitters associated with the right atrial ganglionated plexus (RAGP) of the human heart. Biopsies of epicardial fat containing a portion of the RAGP were collected from eight patients during cardiothoracic surgery and processed for immunofluorescent detection of specific neuronal markers. Colocalization of markers was evaluated by confocal microscopy. Most intrinsic cardiac neuronal somata displayed immunoreactivity for the cholinergic marker choline acetyltransferase and the nitrergic marker neuronal nitric oxide synthase. A subpopulation of intrinsic cardiac neurons also stained for noradrenergic markers. While most intrinsic cardiac neurons received cholinergic innervation evident as punctate immunostaining for the high affinity choline transporter, some lacked cholinergic inputs. Moreover, peptidergic, nitrergic, and noradrenergic nerves provided substantial innervation of intrinsic cardiac ganglia. These findings demonstrate that the human RAGP has a complex neurochemical anatomy, which includes the presence of a dual cholinergic/nitrergic phenotype for most of its neurons, the presence of noradrenergic markers in a subpopulation of neurons, and innervation by a host of neurochemically distinct nerves. The putative role of multiple neurotransmitters in controlling intrinsic cardiac neurons and mediating efferent signaling to the heart indicates the possibility of novel therapeutic targets for arrhythmia prevention.

Atrioventricular block and supraventricular arrhythmias with X-linked muscular dystrophy.

This report describes a family showing muscular dystrophy and atrioventricular block with an x-linked hereditary transmission. Among a known pedigree of 101 family members, 12 males were found to have skeletal muscle involvement and six needed pacemakers around age 30 years. Unlike the x-linked muscular dystrophies of Duchenne and of Becker, the predominant skeletal involvement was in humeral muscles, was usually very mild, and did not produce incapacitation. Cardiac involvement consisted of various atrial arrhythmias and atrioventricular block. The few sporadic reports of other families that describe the same disease under different names are briefly reviewed. Recognition of this subtle muscular dystrophy is important for early detection of incipient complete atrioventricular block to prevent fatal complications by pacemaker insertion.

Systemic membrane defect in the proximal muscular dystrophies.

We studied lymphocyte capping in 61 patients with Duchenne, Becker, limb-girdle, facioscapulohumeral and congenital muscular dystrophies. All showed a markedly diminished percentage of capped cells when compared with 86 normal controls, providing support for previous evidence that an alteration in membrane fluidity may be a common pathogenic feature in several genetically distinct forms of proximal muscular dystrophy. Heterozygous carriers of Duchenne muscular dystrophy showed diminished capping that was indistinguishable from that of afflicted males and was often present even when serum enzyme levels were normal. Studies in 25 families with 16 suspected sporadic cases indicated that no more than four out of 30 afflicted males may represent new mutations. These findings imply that most cases of Duchenne dystrophy might be prevented by a population screening program for carrier females combined with prenatal detection of afflicted males.

Monomelic muscle hypertrophy following transient ischemic attacks: a case report.

A 39-year-old right-handed male suffered several episodes of transient right-sided weakness, sensory loss, and Broca's aphasia at age 31. Diagnostic studies failed to demonstrate any cause for these events. Following a complete recovery, he noted the onset of stiffness and increasing muscle bulk in his right arm, which gradually restricted its use. Simultaneous recordings from contracting biceps and triceps muscles in both arms suggested that the hypertrophy was physiologically induced by an abnormal mechanism providing resistance during phasing activity.

Longitudinal fibre splitting in muscular dystrophy: a serial cinematographic study.

A technique of block surface-staining and serial cinematography was modified to review serial sections of normal and dystrophic muscle from the Bar Harbor 129 Re strain of mice as a preliminary study of fibre splitting in dystrophic muscle. Using this technique, muscle fibres were reconstructed for up to 1·5 mm of their length without difficulty. Split fibres were identified only when the actual separation of fibres was observed. Splitting was seen to be a significant cause of the variations in fibre diameter and was at times responsible for the formation of groups of small atrophic fibres which resembled those seen in denervation atrophy. Complex multiple splitting and recombination of daughter and parent fibres was also observed and reconstructed to scale. These results may have considerable significance for the interpretation of physiological data on both human and murine dystrophic muscle.