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M A Melone

Publications and source records attributed to M A Melone.

27 records · Page 2Linked to original sources
PubMed1987

Distributions of molecular forms of acetylcholinesterase and butyrylcholinesterase in nervous tissue of the cat.

We analyzed the activities of acetylcholinesterase and butyrylcholinesterase, and of the metabolic enzymes enolase and lactate dehydrogenase, in the superior cervical ganglion, ciliary ganglion, dorsal root ganglion, stellate ganglion, and caudate nucleus of the cat; we found that these tissues possess very different levels of enzymic activities. The proportions of the alpha alpha, alpha gamma, and gamma gamma enolase isozymes are also quite variable. We particularly studied the molecular forms of acetylcholinesterase and butyrylcholinesterase, in normal tissues and in preganglionically denervated SCG, in comparison with earlier histochemical findings. The results are consistent with the premise that the G1 (globular monomer) forms of both enzymes are located in the cytoplasm, the G4 (globular tetramer) forms are at the plasma membranes, and the A12 (collagen-tailed, asymmetric dodecamer) form of acetylcholinesterase is at synaptic sites.

Acetylcholinesterase↗
PubMed1984

Scanning electron microscopic study of nerve-muscle junctions in embryonic rat cell cultures.

The morphology of neuromuscular junctions between embryonic rat spinal cord and muscle cells grown in vitro has been studied by scanning electron microscopy (SEM). Histochemical detection of acetylcholinesterase (AChE) spots and autoradiographic detection of acetylcholine receptor protein (AChR) were performed in parallel. At the scanning EM level the contacts exhibit a marked polymorphism; the nervous endings may present as a bulbous swelling, or often as a plexiform network on the surface of the myotubes. Many neuromuscular contacts seem to occur 'passing by'; in other places, neurites processes slide along myotubes without any differentiated contacts. The muscle cell surface does not look substantially modified in the contact area. The distribution of the contacts between nerve and muscle cells is at the same time convergent and divergent.

Animals↗
PubMed1982

Establishment of neuromuscular contacts in cultures of rat embryonic cells: effect of tetrodotoxin on maturation of muscle fibers and on formation and maintenance of acetylcholinesterase and acetylcholine receptor clusters.

The part played by muscle activity was mainly studied in relation to the formation and persistence of cytochemically detectable spots of acetylcholinesterase (AChE) during synaptogenesis. A correlation was found between AChE spot evolution and that of two other morphological synapse markers, silver salt-impregnated nerve endings and clusters of acetylcholine receptors (AChR) exposed to 125I-alpha-bungarotoxin and revealed by radioautography. The formation and persistence of AChE spots were activity-dependent but in the case of neuronally induced synaptic nerve endings and AChR clusters, both morphological markers were independent of such activity. The final evolution and maturation of neuromuscular contacts were linked to the differentiation stage reached by the muscle fibers at the time when they established contact with nerve endings. The fibers acquired this differentiated state independently of tetrodotoxin-blocked muscle activity.

Acetylcholine↗
PubMedDate not supplied

Modulation of in vitro myogenesis induced by different polymer substrates.

The understanding of substrate dependence of cellular differentiation is important in the surface design of biocompatible artificial devices as well as cell-incorporated tissue engineered devices. In an attempt to understand some of the genetic and epigenetic aspects of the control of cell differentiation in the presence of two different materials, Chronoflex (CH) and plasma treated Chronoflex coated with Hyaluronan (CH-HA), we used primary cultures of human myogenic cells, a model that encompasses cell proliferation, migration, fusion, and differentiation dependent gene activation. By testing both the material samples on the growth of human myoblasts in primary cultures, we demonstrated that both CH and CH-HA substrates were able to support the cell growth since they did not affect cell count and DNA synthesis. On the contrary, the degree of myoblast differentiation, assessed as a function of creatine phosphokinase (CPK) activity on living cells, was completely different on the two biomaterials. Indeed, the amount of CPK increased on CH-HA cultured cells as a result of myotube formation, while CH grown myoblasts remained unfused and displayed no increase on the CPK activity even after 12 days culture. Moreover, the expression level of MyoD and myogenin mRNA, both related to myogenic cell differentiation, appeared extremely low in CH-grown cells, while they were rapidly induced in CH-HA cultured myoblasts.

Journal Article↗