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Biomedical subjects

P Martel

Publications and source records attributed to P Martel.

7 recordsLinked to original sources
PubMed1992

Altered response to growth factors in rat epithelial liver cells overexpressing human c-Fos protein.

Human c-fos cDNA was transfected into normal rat liver epithelial (REL) cells to identify cellular modifications associated with high expression of c-Fos protein. Responses to EGF and TGF beta were examined in the different cell lines, under anchorage-dependent and -independent conditions. Sensitivity to both factors was modified in transfected cells. While parental cells in monolayer did not respond to EGF, c-fos containing cells growth was stimulated by this factor. Overexpression of c-Fos protein led to an enhanced TGF beta-induced growth inhibition under anchorage dependent conditions, and TGF beta abolished spontaneous growth in soft agar of the cell lines containing c-fos oncogene. The mechanisms underlying the increased sensitivity to TGF beta in c-fos transfected cells are still to be determined.

Animals↗
PubMed1992

Transforming growth factor beta 1 (TGF-beta 1) inhibits growth of a human ovarian carcinoma cell line (OVCCR1) and is expressed in human ovarian tumors.

The effects of EGF and TGF-beta 1 on the proliferation of 2 ovarian carcinoma cell lines (IGROV1 and OVCCR1) were evaluated. The cell lines were adapted to grow in a restricted serum (0.5%) medium. EGF was required for proliferation of both ovarian cell lines. Low doses of TGF-beta 1 inhibited clonogenic capacity and attenuated the EGF-mediated stimulation of DNA synthesis in OVCCR1 cells. TGF-beta 1 inhibited OVCCR1 cell proliferation by blocking the cell cycle at the G1/S transition. TGF-beta 1 did not affect either clonal or monolayer growth of IGROV1 cells. Both cell lines express type-I and type-III TGF-beta receptors, suggesting that the unresponsiveness of IGROV1 cells to TGF-beta 1 occurs at a post-receptor level. TGF-beta 1 mRNA was detected in OVCCR1 cells and in 8 out of 11 of the ovarian tumor specimens examined.

Cell Division↗
PubMed1992

Biophysical aspects of neutron scattering from vibrational modes of proteins.

This review describes a major portion of the published work on neutron scattering experiments aimed at measuring large scale motions in proteins. The importance of these motions for enzyme function and oxygen transport is indicated. The theory applicable to each type of neuron scattering measurement is given and results are discussed with a view to biological relevance. New experiments are suggested and a comparison of neutron scattering data is made with results from other techniques such as raman scattering, infrared absorption, photolysis and molecular dynamics simulations.

Animals↗
PubMed1992

[The treatment of severe dysplasias by CO2 laser: the respective indications for vaporization and conization. 84 cases].

Fifty-nine conisations and 25 vaporizations were carried out using laser CO2 in order to treat a series of 84 cases of severe dysplasias (CIN III). After a follow-up of 4 and 12 months (median period of observation 25 months) it was found that out of 74 patients that were followed up in this way 72 had benefitted from the use of the treatment. There were 5 cases however of recurrence of dysplasia (1 CIN I, 2 CIN II, 2 CIN III). These had further treatment with laser. Four of those were controlled properly, the fifth had to have surgery. Complications of treatment did not occur when vaporization was used and only rarely when conisation was used. With vaporisation it is not possible to obtain a piece for histological examination, but if it is done according to precise criteria it is safe (7 mm depth at least and vaporisation carried out to 3 mm beyond the lesions). It can be used particularly in young patients who have never been pregnant. If these have been examined carefully with directed biopsies taken colposcopically and where the lesion is strictly limited to the exocervix and the transformation zone has been seen and the lesion is small (2 cm of less), 84% were controlled therapeutically and using Bruhat's criteria the success rate was 96%. Conisation was effective for every one of the other cases. Laser CO2 probably lessens local complications of the procedure and if vaporization is carried out on the rim of the cervix better control of the condition is obtained (98% controlled in the period under review).

Adult↗
PubMed1979

Base crystallization and base stacking in water.

2H2O solutions of 6-methylpurine and N6,N9-dimethyladenine have been examined by neutron diffraction. Comparison of the scattering from various molar solutions of 6-methylpurine with the scattering from its crystalline precipitates indicated base stacking in solution with a separation of approximately 0.34 nm. In particular at 1.75 M the effective stacking number in 6-methylpurine, as seen by neutron diffraction, was found to be approximately nine. Attempts to observe similar scattering from N6, N9-dimethyladenine were hampered because solutions with a molarity greater than or approximately 0.02 tended to form filamentary crystallites as a function of time. An analysis of the autocatalytic reaction involved in the formation of these dendrites is given. The rate constant is found to be 2.12 +/- 0.05 M-1 h-1. By comparing the diffraction from wet and dry crystallites it is concluded that hydrophilic interactions mediate the aggregation of both bases in water.

Crystallization↗
PubMed1977

Projections from the inferior olive to the cerebellar nuclei in the cat demonstrated by retrograde transport of horseradish peroxidase.

The method of intracerebral injections of horseradish peroxidase has been applied to demonstrate a projection from the inferior olivary nucleus to the intracerebellar nuclei in the cat. Cells labeled by the transported enzyme can be observed in different regions of the olive according to the localization of the injection. The caudal half of the medial and dorsal accessory subdivisions, the dorsal cap and nucleus beta project to the fastigial nucleus. In the rostral half of the olive, the accessory subdivisions of that nucleus and the dorsomedial cell column send fibers to the interposed nuclei while the principal olive and the ventrolateral outgrowth are connected with the dentate nucleus. It is likely that these fibers are collaterals of the climbing fibers.

Animals↗