Capacity of foetal spinal cord obtained from dystrophic mice (dy2J) to promote muscle regeneration

Differentiation in dystrophic muscle cultures from mice of different ages

Muscle from dystrophic (129 ReJ dy/dy) mice, aged 1, 2, 3, 4, and 6 months, was cocultured with normal embryonic mouse spinal cord. Cultures were scored for regeneration (myotubes) and differentiation (cross-striated or contracting fibers) over a 28-day period. Although muscle from dystrophic mice of all ages was able to regenerate, the ability to differentiate decreased with the increasing age of the mouse. Muscle from litter-mate control mice of different ages regenerated and differentiated equally well.

The application of organotypic nerve cultures to problems in neurology with special reference to their potential use in research into neuromuscular diseases

In organotypic nerve cell cultures there is production of central and peripheral myelin as well as synapse formation and long-term survival (months) of neuronal cell types and their associated glia. These cultures can be viewed continuously by light microscopy and are amenable to both electron microscopy and electrophysiology. Organotypic cultures have been used in studies of myelin formation and of demyelination by "toxic" sera, in the search for a neurotoxic factor in motor neurone disease and in studies of neurotrophic viruses. They have also been used to demonstrate the effects of toxins such as cyanide, lead, various industrial chemicals and neurotransmitter analogues (such as kainic acid) on myelin, axons and neurones in culture. They are currently being used in conjunction with small bundles of teased adult mammalian muscle fibres. Such bundles, cultured alone, do not regenerate. However, in the presence of various foetal tissues (neuronal or non-neuronal), the muscle regenerates to form new myotubes. Only in the presence of foetal spinal cord neurones will these myotubes differentiate further to form cross-striated, contracting muscle fibres. If the spinal cord tissue is removed when contractions have just begun, the muscle fibres revert to undifferentiated myotubes.

Mosaic analysis of dystrophic embryos aggregated with normal chimeras: an approach to mapping the site of gene expression

Genotypically dystrophic muscle in mouse chimeras of dystrophic leads to and comes from normal genotype has been influenced to develop normally and remain healthy. A significant extramuscular component that effects the expression of the muscle disease in homozygous dystrophic mice is thereby implicated. The potential application of the chimera preparation in further elucidating the source and the nature of that extramuscular influence is outlined.

Enzyme alteration in skeletal muscle of mice with muscular dystrophy

1. Developmental enzyme alterations were investigated in skeletal muscle of the hereditary progressive muscular dystrophy (PMD) mice of C57BL/6J strain. 2. Enzymes examined were classified into three groups according to changes of activities in dystrophy muscle during ageing. Activities of creatine kinase (EC 2.7.3.2), pyruvate kinase (EC 2.7.1.40), glycogen phosphorylase (EC 2.4.1.1), and fructose-biphosphate aldolase (EC 4.1.2.13), each of which had the respective muscle specific isoenzyme of extremely high activity in normal adult skeletal muscle, decreased rapidly in dystrophy muscle from the early stage of the disease with ageing. Activities of glycogen synthase (EC 2.4.1.11) and hexokinase (EC 2.7.1.1) were higher in dystrophy muscle in the early stage but decreased gradually to lower levels than those in the control with ageing. Activities of glucose-6-phosphate dehydrogenase (EC 1.1.1.49) were always much higher in dystrophy muscle than in the control, with no relation to ageing. 3. Isoenzymes of creatine kinase, pyruvate kinase and phosphorylase in dystrophy muscle were mainly the muscle types, indicating that muscle differentiation was not blocked profoundly even in dystrophy muscle. In limited cases, especially in the early stage of the disease, very weak activities of the non-muscle fetal type isoenzymes of creatine kinase and phosphorylase were detected, apparently associated with partial muscle regeneration in dystrophy muscle.