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Biomedical subjects

G Cossu

Publications and source records attributed to G Cossu.

At least 163 records · Page 9Linked to original sources
PubMed1980

In vitro differentiation of satellite cells isolated from normal and dystrophic mammalian muscles. A comparison with embryonic myogenic cells.

Satellite cells were isolated from skeletal muscles of adult normal and dystrophic mice (C57/6J/dy strain) by sequential digestion of tissue fragments with collagenase, hyaluronidase and trypsin. These cells exhibit in culture similar behaviour to that of embryonic myoblasts, undergoing an initial duplicative period lasting about 2--3 days, followed by a shorter phase (1--2 days) of rapid cell fusion. During the duplicative phase most of the satellite cells appear round-shaped, whereas embryonic myoblasts appear typically spindle-shaped: both cell types actively incorporate [3H]thymidine. During the subsequent days of culture an increasing number of satellite cells becomes spindle-shaped; afterwards the cells contact each other and fuse into multinucleated myotubes. The majority of spindle-shaped satellite cells is unable to incorporate [3H]thymidine, thus behaving as post-mitotic cells. Concomitantly with satellite cell fusion, an increase of about 80-fold of creatine phosphokinase (CPK) specific activity is observed. Satellite cells are able to recognize co-cultured embryonic myoblasts ([3H]thymidine-labelled): hybrid myotubes containing labelled and unlabelled nuclei are formed in these experimental conditions. Satellite cells from dystrophic animals are able to differentiate in culture and do not show appreciable differences as compared to their normal counterparts. In dystrophic myotubes, however, CPK specific activity is almost twice that observed in normal myotubes. Human dystrophic satellite cells from biopsies of adult muscle cultured in similar conditions grow and fuse into multinucleated myotubes showing a behaviour identical to normal controls.

Animals↗
PubMed1980

Acquired ocular-motor apraxia and right-sided cortical angioma.

A case of acquired ocular-motor apraxia featured by failure in voluntary initiation of lid closure, horizontal and vertical eye movements is reported. Electrographic and neuropsychological assessment pointed out several signs referable to bilateral frontal and right parietal lobe involvement, confirmed by neuroradiological finding.

Apraxias↗
PubMed1978

Biosynthetic changes in myosin heavy subunit during myogenesis in culture.

In primary culture of chick embryo muscle cells myosin synthesis is detected in mononucleated cells and increased at the onset of fusion with a maximal increment of 20-fold per plate in differentiated myotube. The possibility that the myosin synthetized by duplicating myoblast could be different from that present in post-mitotic myoblast and myotube was evaluated by investigating the regulation of its synthesis and the turnover of the molecule. Following Actinomycin D treatment (0.05 microgram/ml, 8 h), myosin synthesis is partially affected (about 50% inhibition) in pre-fusion myoblast while the synthesis is more sensitive to the drug at the onset of fusion (80% inhibition). With the progress of the differentiative stage the half-life of the molecule increases from 30 h in duplicating myoblasts to 200 h in fibers. The half-life of myosin synthetized by duplicating myoblasts in the explanted embryonic muscle, is 12 h. These data show different features of myosin heavy chains related to specific stages of differentiation and suggest the possibility that modulative changes of the molecule could induce its functional maturation during myogenesis.

Animals↗
PubMed1977

DNA replication during muscle cell differentiation: identification of multiple DNA-dependent DNA polymerases.

DNA-dependent DNA polymerases have been studied during chick embryo muscle differentiation in vitro. The total activity, extracted at both low and high ionic strengths, does not change throughout the differentiative process, although DNA synthesis stops at the moment of fusion. Analyses by glycerol gradient centrifugation of the extracts at low and high ionic strengths show two major DNA polymerase forms, one sedimenting at 7.5 S and another at 3-4 S. Both enzymes are present in similar amounts in duplicating myoblasts and in post-mitotic myotubes. These data suggest that the arrest of DNA synthesis which accompanies myoblast differentiation is not dependent on the disappearance or decrease of the major DNA polymerase activities described.

Animals↗
PubMedDate not supplied

Electrophoretically silent hemoglobin mutants as revealed by isoelectric focusing in immobilized pH gradients.

The applications of isoelectric focusing in immobilized pH gradients to the analysis of (i) human hemoglobin mutants, (ii) animal hemoglobin mutants (from cattle, sheep, dog and mouse), and (iii) tryptic digests of alpha and beta chains, are discussed and evaluated. Immobilized pH gradients appear to be an excellent tool for screening of genetic polymorphism and for detecting "silent mutants", i.e. those substitutions involving amino acids with nonionizable side chains. At present, not even capillary zone electrophoresis, claimed to have a resolving power equivalent to 1 million theoretical plates, has shown a resolution capability comparable to that of immobilized pH gradients, at least in the field of protein separation.

Animals↗