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M Couturier

Publications and source records attributed to M Couturier.

At least 91 records · Page 5Linked to original sources
PubMed1983

Mini-F encoded proteins: identification of a new 10.5 kilodalton species.

The elements which ensure the maintenance of the F plasmid are located in its f5 EcoRI restriction fragment. This f5 fragment constitutes a mini-F plasmid showing the same stability and copy number control as the entire F plasmid. The proteins expressed in minicells by wild-type or mutated f5 fragments were analysed by pH gradient two-dimensional electrophoresis. We identified seven f5-encoded polypeptides and located their genes on the F map. Among them, H1, an acidic polypeptide of mol. wt. 10.5 K, had not been detected before. It is in fact the most abundant f5-encoded polypeptide identified so far. In addition, we showed that both 10.5-K and 12-K protein bands detected by SDS-polyacrylamide gel electrophoresis are, respectively, composed of two polypeptides, H1 and H2, G1 and G2, of different isoelectric points. Polypeptides H2 and G2, respectively, share common coding sequences with polypeptides H1 and G1. Their possible biological significance is discussed. The sequences coding for polypeptides H1/H2 and G1/G2 are clustered in a 800-bp long region located between the two mini-F origin sites and are proposed to be organized as an operon. The results reported in the accompanying paper point out the importance of polypeptides G1/G2 and H1/H2 in the relationship between the F plasmid and its host.

Bacterial Proteins↗
PubMed1983

Ham22, a mini-F mutation which is lethal to host cell and promotes recA-dependent induction of lambdoid prophage.

A mini-F region 800 bp long, located between the two F origin sites, plays an essential role in the relationship between the F plasmid and its host. This region comprises two sets of overlapping coding sequences: the first set codes for the newly identified H1 and H2 polypeptides; the second set codes for polypeptides G1 and G2. A mini-F amber mutation (Ham22) causes the virtual disappearance of polypeptides H1 and H2 but only slightly reduces synthesis of polypeptides G1 and G2. This mutation: (i) renders mini-F hybrids lethal to the host cells (conditional Hos- phenotype for host survival) and (ii) causes the induction of a resident prophage in recA+ strains (conditional Map- phenotype for maintenance of the prophage). When an additional mutation prevents the synthesis of polypeptides G1 and G2, both the lethal character and the induction of the prophage are abolished. We conclude: (i) that polypeptides G1 and/or G2 are specific mini-F polypeptides involved in the plasmid-mediated killing effect and in the recA-dependent induction of the resident prophage and (ii) that, in normal conditions, polypeptides H1 and/or H2 negatively control (directly or indirectly) the action of polypeptides G1 and/or G2. In relation to the analysis of indirect induction mediated by u.v.-irradiated lambda mini-F hybrids, we propose that polypeptides G1 and/or G2 are specific mini-F products involved in the activation of the bacterial SOS pathway. The H1/H2 and G1/G2 polypeptides could constitute the controlled mini-F signal enabling the coordination between cell division and F plasmid replication.

Bacteriophage lambda↗
PubMed1983

Influence of two cell harvesting methods on intracellular ATP and amino acid concentrations in human fibroblast cultures.

The intracellular ATP and amino acid concentrations were determined in human fibroblast cultures reaching confluence. The values obtained were very different, depending on the cell harvesting method: trypsinization or scraping. Trypsinization appeared to be the better method for measuring the ATP concentrations (21.25 +/- 0.96 nmol per mg cell protein), this level being much lower with scraping. On the contrary, scraping was the most appropriate method for amino acid measurement. This work underlines the importance of harvesting methods for metabolic studies in human cell cultures.

Adenosine Triphosphate↗
PubMed1983

The value of early fibreoptic bronchoscopy after aspiration of gastric contents.

Fibreoptic bronchoscopy was undertaken in 26 patients upon hospital admission, to assess if they were suffering from pulmonary lesions subsequent to the aspiration of gastric contents. In 24 of these patients erythematous lesions were observed (sensitivity of the procedure: 92.3%), mainly on the carina. Distal to the carina, the lesions were observed less frequently. The procedure caused no complications in any of the patients studied.

Adolescent↗
PubMed1982

Computed tomographic demonstration of the effects of bromocriptine on pituitary microadenoma size.

A group of 17 strictly intrasellar prolactin-secreting pituitary adenomas between 2 and 9 mm in size was examined by computed tomography before and after bromocriptine therapy of 3 months to 1 year duration. These findings were compared with clinical and biological data. Bromocriptine therapy was effective clinically and biologically in 14 of the 17 cases. Of the 15 intrasellar adenomas in nonpregnant patients treated with bromocriptine, six disappeared completely with normalization of the pituitary appearance, five decreased approximately 50% in volume (three showed an increase in density, two a decrease), and four remained unchanged in size (two showed increased density, two showed very low densities).

Adenoma↗
PubMed1982

[The influence of age on the course and prognosis of carcinomas of the larynx and hypopharynx].

On the basis of clinical impressions only, the authors had felt the carcinomas of the larynx and hypopharynx were probably graver in young subjects than in the elderly, and that age was a determinant factor in therapeutic decisions. 585 records including 216 carcinomas of the piriform fossa and 369 carcinomas of the larynx were studied over a period of 8 years. This study failed to reveal any difference related to age between populations aged less than 60 years and more than 60 years, both with regard to the prevalence of carcinomas whatever the siten the presence or absence of nodes, histological spread, loco-regional prognosis and actuarial survival. The latter parameter was studied by establishing the distribution between patients aged less than 55 and those 55 and over to obtain equivalent groups in terms of numbers. Overall, the prognosis seemed to be rather better in the younger patients, which would imply a therapeutic attitude independent of age.

Adult↗
PubMed1982

[Comparative study of the significance of lymphadenopathy in carcinomas of the hypopharynx, larynx and epiglottis. 574 cases].

The significance of the absence or presence of lymphadenopathy is not the same in relation to the site of the primary tumour. This study involved 574 cases, including 213 carcinomas of the piriform fossa and 361 laryngeal carcinomas, and revealed errors of omission (No - N+) in carcinomas of the piriforme fossa (50% cases) and the possibility of errors of commission (N not equal to - N - in carcinomas of the larynx. This merely confirmed the high level of lymphatic affinity of carcinomas of the piriform fossa, but at the same time emphasised the relative reliability of the clinical assessment of relevent classifications.

Carcinoma↗
PubMed1980

Nov Presse Med.

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Acute Kidney Injury↗
PubMed1980

Suprasellar choristoma.

A case of choristoma of the posterior lobe of the pituitary is presented. The clinical presentation suggested chromophobe pituitary adenoma and the true diagnosis was only established on histological esamination. Despite the patient's advanced age her-operative course was satisfactory, but the disturbances of endocrine and visual function remained virtually unchanged. Perusal of the literature shows that this is the twentieth case of suprasellar or neurohypophyseal choristoma so far published. It provides an opportunity to review the clinical presentation, radiology and treatment, as well as to discuss the histiogenesis and nature of this rare pituitary tumor.

Aged↗
PubMed1979

Construction in vitro of "phage-plasmid" chimerae: a new tool to analyse the mechanism of plasmid maintenance.

In this paper, we report the construction in vitro of chimerae between lambdoid replacement vectors (Murray et al., 1977) and the miniF Apr plasmid: pSC138 (Timmis et al., 1975). lambdaF recombinants were shown to be chimerae between the lambda and the F replicons. By genetical tests, we have demonstrated that both lambda and F replication mechanisms are functional: the lambdaF recombinant behaves as a non defective plaque forming phage on lambda sensitive bacteria and establishes itself as a stable plasmid on recA F- homoimmune bacteria. In the extra-chromosomal state, the lambdaF recombinant apparently retains the controlled autonomous replication and the FI incompatibility characteristics of the F plasmid. The potential experimental uses of these phages are discussed.

Coliphages↗
PubMed1978

Mu-1 directed inhibition of DNA breakdown in Escherichia coli, recA cells.

The spontaneous DNA breakdown exhibited by recA strains, is reduced after heat induction of a thermoinducible Mu-1 prophage. This inhibition is dependent upon RNA synthesis, suggesting that Mu-1 directs synthesis of a recBC nuclease inhibitor, analogous to the product of the lambda gam gene. The genetic evidence presented here shows that Mu-1 enables a lambda red gam phage to grow on a recA host. The in vitro assay for ATP-dependent exonuclease activity reveals a complete inhibition of this activity 30 min after induction of the Mu-1 prophage.

Coliphages↗