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Biomedical subjects

N Denis

Publications and source records attributed to N Denis.

9 recordsLinked to original sources
PubMed1992

[Surgical treatment of spinal deformities in Duchenne muscular dystrophy].

Forty seven Duchenne Muscular Dystrophy patients, operated on for spinal deformity with segmental spinal instrumentation according to Luque's technique, are reviewed with a mean post-operative follow up of 4 years 4 months. The study of the results obviously showed the interest of Luque Galveston technique for the treatment of severe curves with pelvic obliquity, whereas Dove's rectangle is an interesting choice for the early instrumentation. A total spinal arthrodesis can probably be avoided in these patients, which often demonstrate a satisfying spontaneous fusion after instrumentation. The general and mechanical complications are described, according to the consequences they have on the management technique of these patients.

Adolescent↗
PubMed1991

Stimulation of methotrexate resistance and dihydrofolate reductase gene amplification by c-myc.

We have hypothesized that the c-myc oncogene might promote DNA amplification. Resistance to methotrexate (MTX), a widely used cancer chemotherapeutic agent, often results from amplification of the gene coding for the target enzyme, dihydrofolate reductase (DHFR). We report here that gratuitously induced expression of c-myc in rat fibroblasts grown in the presence of MTX greatly increases the number of colonies resistant to the drug. This effect is not related to an alteration of cell growth, and it can also be observed to a lesser extent when c-myc is induced prior to selection in MTX. The DHFR gene is amplified in nearly half of the colonies cultured under selection conditions. Given the likely role of the c-myc product in DNA replication, these results strongly suggest that expression of c-myc plays a role in methotrexate resistance by promoting DNA amplification.

Animals↗
PubMed1987

c-myc oncogene expression inhibits the initiation of myogenic differentiation.

The role of c-myc oncogene expression in myogenic differentiation has been established by transfecting rat myoblasts of the L6 cell line with plasmid pMT-myc, in which the c-myc coding sequences were under the control of the metallothionein I promoter. We observed that the constitutive expression of the exogenous c-myc gene inhibits muscular differentiation. A diminution of the endogenous c-myc gene expression occurs within the first 24 h after the transfer of the cells to a differentiating medium. This early decrease of c-myc expression is required for cell differentiation to occur. We have also observed that exogenous myc gene expression has no effect on endogenous myc expression.

Animals↗
PubMed1987

[Oncogenes].

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Cell Transformation, Neoplastic↗
PubMed1987

Expression of c-myc is under dietary control in rat liver.

Expression of c-myc has often been related to the control of growth and differentiation of a variety of cell types. However, in some cases, such a relation has not been found. The rate of cell division is very low in liver, but c-myc expression is yet easily detected. We show here that a short-time physiological fasting results in a dramatic decrease of c-myc expression in rat liver. This effect does not seem to be dependent on glucagon, since administration of glucagon leads to an increase in c-myc mRNA. This is to our knowledge, the first evidence of a physiological variation of proto-oncogene expression linked to food intake, and we suggest that this variation could play a role in liver cell growth control.

Animals↗