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Biomedical subjects

J A Witkowski

Publications and source records attributed to J A Witkowski.

At least 109 records · Page 6Linked to original sources
PubMed1980

Protein degradation in skin fibroblasts from patients with Duchenne muscular dystrophy.

The rates of degradation of [3H]leucine-labelled proteins have been measured in cultures of skin fibroblasts obtained from normal controls (five subjects) and patients with Duchenne muscular dystrophy (six subjects). Cultures were incubated with [3H]leucine (10 microCi/ml) for 60 min to label "short-lived" proteins, and with [3H]leucine (5 microCi/ml) for 60 h to label "long-lived" proteins. Optimal wash procedures were devised for removal of [3H]leucine from the extracellular space and from cell pools before beginning degradation measurements. Re-utilization of [3H]leucine released from degraded labelled proteins was prevented by supplementing the medium with 4mM-leucine. Rates of degradation did not depend on the growth state of the cells or on cell age over the range used (passages eight-20). Degradation of long-lived proteins was approximately linear over a 24h period, at a rate of 1.0% per h. 30% of short-lived protein was degraded within 6h. No differences were observed between protein degradation in normal fibroblasts and in those from patients with Duchenne muscular dystrophy.

Adolescent↗
PubMed1979

Reduced adhesiveness between skin fibroblasts from patients with Duchenne muscular dystrophy.

The intercellular adhesiveness of skin fibroblasts from patients with Duchenne muscular dystrophy and normal controls has been measured by determining the collision efficencies of cells using the couette viscometer. The collision efficencies for dystrophic cells were significantly lower that those for normal cells (0.01 greater than P greater than 0.005), indicating that dystrophic cells are less adhesive than normal cells.

Adult↗
PubMed1979

Maturation of human skeletal muscle fibres in explant tissue culture.

Human foetal skeletal muscle was grown in explant cultures and the development of myotubes was monitored morphologically and by the development of membrane potential and acetycholine sensitivity. Migration of uninucleate cells from the explants occurred in the first day of culture and formation of multinucleated myotubes took place between 7 to 10 days. Early myotubes were variable in appearance, being either flat and nonrefractile or narrow and cylindrical. Some cross-striated cells were observed. Resting membrane potentials were around -25mV and there was great variation in myotube sensitivity to acetylcholine. After about 6 weeks in culture most myotubes were of the refractile type. Many had hypolemmal nuclei and were cross-striated; some contracted spontaneously. All myotubes had developed high sensitivity to acetylcholine although there had been no increase in resting membrane potential.

Acetylcholine↗