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Biomedical subjects

L Baugnet-Mahieu

Publications and source records attributed to L Baugnet-Mahieu.

At least 19 recordsLinked to original sources
PubMed1992

[Neoadjuvant chemotherapy, with mitoxantrone, cyclophosphamide and fluorouracil, in operable breast cancer of intermediate stage: first results of a phase II study in 40 patients].

Forty patients with intermediate stage (T2 > 3 cm-T3, N0-N1) operable breast cancer received neoadjuvant chemotherapy by MCF (mitoxantrone, cyclophosphamide, 5-fluorouracil). Four cycles were administered at 3-week intervals. The obvious hematological toxicity (64% of grade III for the leucocytes and up to 34% of grade IV for the granulocytes) was rapidly reversible and did not hinder completion of the treatment. Ten patients showed a complete remission and a tumor volume regression of more than 50% was observed in 12 other patients. Tumor shrinkage allowed breast-saving surgery in 50% of the cases. A complete sterilisation of the surgical specimen was found in only two of the 40 patients and a few persisting neoplastic cells were found in ten other cases. A positive response at the level of the axillary lymph nodes was also obtained in more than 50% of the cases. In 25 of the 36 cases examined, the primary chemotherapy induced cellular lesions (fibrosis, necrosis) at the tumor level. A feasibility study was undertaken in order to determine quantitatively several biochemical parameters (steroid hormone receptors, cathepsin D, c-erbB-2 oncoprotein) in very small tumor samples obtained by Tru-Cut before any treatment and in surgical specimens. In the future, these micromethods will be used systematically with the aim of estimating the value of these potential prognostic factors for therapeutic follow-up of the patients.

Adult↗
PubMed1990

Chromosome aberrations in patients treated with telecobalt therapy for glioblastoma.

The yield of dicentric chromosomes has been recorded in peripheral blood lymphocytes of patients undergoing telecobalt therapy for glioblastoma. Blood samples were taken by venipuncture, prior to the first radiotherapy session and 24 h after 10, 20 and 30 Gy to the tumor volume. On the basis of the maximum likelihood method, the yield of chromosome aberrations was best fitted by a linear quadratic dose-response relationship. According to this relationship, the dose inducing ten dicentrics at the target volume is 58 Gy, a value considerably higher than those found after radiotherapy for mammary carcinoma (15 Gy) or for pelvic tumors (5.62 Gy). Our results indicate that, in the case of fractionated exposures, confined to a small volume of the body, it is not possible to estimate the total dose administered and that the method only provides an estimate of the proportion of the lymphocytes irradiated.

Brain Neoplasms↗
PubMed1990

Chromosome aberrations induced in vitro in human lymphocytes by monoenergetic 2.5 MeV neutrons and 60Co gamma rays.

The aim of the present experiments was to evaluate the relative biological effectiveness (RBE) of monoenergetic 2.5 MeV neutrons, in view of the scarcity of data on the RBE of neutrons in this energy range. Human peripheral blood lymphocytes from two donors were exposed to doses of neutrons ranging from 0.005 Gy to 0.5 Gy. Gamma rays produced by a telecobalt therapy unit were used as reference radiation. RBE values were of the same order of magnitude, whatever was the model of the dose-response curve chosen for the neutrons (linear or linear-quadratic). As expected, RBE increased markedly with decreasing doses and went beyond 30 at a dose level of 0.2 Gy. The present results, compared with RBE values obtained with neutrons of higher energy (6.5, 14 and 21 MeV), confirm that low energy neutrons are more effective in producing genetic effects, especially at low doses.

Adult↗
PubMed1989

[Thyroid function and cancer].

Despite extensive epidemiological and biochemical studies, the effects of a thyroid dysfunction on the incidence and progress of human cancer have been, for many years, a controversial subject. Endocrine manipulations on laboratory animals clearly demonstrate the influence of thyroid hormones on the induction and growth of several types of experimental tumors: lymphomas, mammary tumors, primary or transplanted hepatomas. In vitro, triiodothyronine also plays an early and critical role in the neoplastic transformation of cultured cells by X-rays, chemical carcinogens and RNA- and DNA-viruses. At the molecular level, the effects of thyroid hormones on the alterations of gene expression accompanying neoplasms remain unknown. Yet, the presence of nuclear triiodothyronine receptors in experimental and human tumors and the recent discovery, by several authors, that the cellular counterpart of a viral oncogene (v-erb A) encodes a thyroid hormone receptor, suggest: either a direct influence of the hormone on the initiation and/or the progress of these tumors; or an indirect effect, via the modulation of another metabolic regulator, for example a polypeptide growth factor (Epidermal Growth Factor, Transforming Growth Factor).

Animals↗
PubMed1987

Late division kinetics in relation to modification of protein synthesis in mouse eggs blocked in the G2 phase after X-irradiation.

Mouse zygotes (BALB/c) blocked in the G2 phase of the first cell cycle after X-irradiation were allowed to develop in culture medium. Delayed cleavage occurred at the same time in embryos exposed to 1 or 2 Gy and late division coincided with the second division in controls. Two-dimensional electrophoresis showed that blocked irradiated embryos underwent the same modifications in protein synthesis as control embryos of the same age, except during first mitosis, for three polypeptide sets of 30, 35 and 45 kilodaltons molecular weight. The most remarkable difference between them was the appearance in cleaving controls of three spots at 35 kilodaltons that were absent in blocked irradiated embryos. It is assumed that blocked embryos 'missed' some signal necessary for cell division, but remained ready to cleave when a second signal occurred. Eggs from the BALB/c strain were particularly susceptible to this effect of X-irradiation but it was also found in eggs from other strains, irradiated with much higher doses.

Animals↗
PubMed1987

[Post-translational modifications of various polypeptides in relation to the first mitosis in BALB/c mouse ova].

After X-irradiation at pronuclear stage, mice eggs from certain strains are reversibly blocked in G2 phase of the first cell cycle. However, evolution of polypeptide synthesis takes place in a normal way, except for three polypeptides sets of 30, 35 and 45 kd molecular weight that appear in dividing controls and not in blocked, irradiated eggs. It is shown that those first mitosis-specific polypeptides result from post-translational modifications, involving phosphorylations.

Animals↗
PubMed1986

Thyroid function in women with breast cancer.

The thyroid function was evaluated in a study group of 226 breast cancer patients and in control groups, consisting of 125 patients with various other malignancies, 61 women with benign breast disease and 166 healthy blood donors. The mean serum concentrations of total T3 and T4 were significantly higher in the breast cancer group than in the controls. The mean TFI (thyroid function index), measured by two indirect techniques (T3RU, T4/TBG) or by direct free T4 measurement, was also significantly higher in this group of patients than in controls. Individual values of TFI exceeding the upper limit of the normal range were related with elevated total T4 levels and not with abnormal concentrations of total TBG. Eight women with breast cancer (3.5%) and one patient with head and neck cancer were clinically hyperthyroid. No case of overt hypothyroidism was observed. There was no relation between thyroid function and spread of the disease (TNM). The control groups, including patients with other-than-breast cancers, did not show any significant modification of the thyroid function tests. In the present study, breast cancer patients, as a group, show a thyroid dysfunction distinct from the non-specific abnormalities (low T3 syndrome) frequently observed in patients with a variety of acute or chronic non-thyroidal illnesses.

Adult↗
PubMed1978

Characterization by molecular hybridization of two viral populations derived from a radiation leukemia virus.

Two leukemogenic viral populations were derived from a radiation leukemia virus of the C57BL mouse. One (FB), in which only B-tropic virus could be detected, was obtained in vivo by serial passage of cell-free extract in newborn rats. The second (3C), a complex containing at least B-tropic and xenotropic viruses, was produced in vitro by a permanent cell line (13-3C) established from the spleen of a virus-infected C57BL mouse. In molecular hybridization experiments, the 70S RNA of Gross leukemia virus hybridized 96 and 78% of FB and 3C radioactive complementary DNA's, respectively, with a relatively high thermal stability of the duplexes formed. In contrast, the 70S RNA of Rauscher leukemia virus hybridized 23 and 20% of the FB and 3C DNA probes, respectively, with a low thermal stability. The rat-grown FB virions exhibited 50% genome homology with the viruses produced in vitro on the 13-3C cells. Finally, hybridizing the FB and 3C probes with normal or leukemic mouse spleen DNA's resulted in 89 to 100% homology. The rat-grown virions did not appear to contain detectable rat cellular DNA sequences, while about 20 complete copies of their nucleotide sequences were detected in covalent linkage with FB-infected rat spleen DNA. These findings strongly support the endogenous murine origin of the investigated virions.

AKR murine leukemia virus↗