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Biomedical subjects

P Renault

Publications and source records attributed to P Renault.

At least 55 records · Page 3Linked to original sources
PubMed1993

Gene inactivation in Lactococcus lactis: histidine biosynthesis.

Lactococcus lactis strains from dairy and nondairy sources were tested for the ability to grow in the absence of histidine. Among 60 dairy strains tested, 56 required histidine, whereas only 1 of 11 nondairy strains had this requirement. Moreover, 10 of the 56 auxotrophic strains were able to grow in the presence of histidinol (Hol+), the immediate histidine precursor. This indicates that adaptation to milk often results in histidine auxotrophy. The histidine operon was detected by Southern hybridization in eight dairy auxotrophic strains tested. A large part of the histidine operon (8 kb, containing seven histidine biosynthetic genes and three unrelated open reading frames [ORFs]) was cloned from an auxotroph, which had an inactive hisD gene, as judged by its inability to grow on histidinol. Complementation analysis of three genes, hisA, hisB, and hisG, in Escherichia coli showed that they also were inactive. Sequence analysis of the cloned histidine region, which revealed 98.6% overall homology with that of the previously analyzed prototrophic strain, showed the presence of frameshift mutations in three his genes, hisC, hisG, and hisH, and two genes unrelated to histidine biosynthesis, ORF3 and ORF6. In addition, several mutations were detected in the promoter region of the operon. Northern (RNA) hybridization analysis showed a much lower amount of the his transcript in the auxotrophic strain than in the prototrophic strain. The mutations detected account for the histidine auxotrophy of the analyzed strain. Certain other dairy auxotrophic strains carry a lower number of mutations, since they were able to revert either to a Hol+ phenotype or to histidine prototrophy.

Amino Acid Sequence↗
PubMed1992

Divergence of Genomic Sequences between Lactococcus lactis subsp. lactis and Lactococcus lactis subsp. cremoris.

Relatedness between Lactococcus lactis subsp. cremoris and L. lactis subsp. lactis was assessed by Southern hybridization analysis, with cloned chromosomal genes as probes. The results indicate that strains of the two subspecies form two distinct groups and that the DNA sequence divergence between L. lactis subsp. lactis and L. lactis subsp. cremoris is estimated to be between 20 and 30%. The previously used phenotypic criteria do not fully discriminate between the groups; therefore, we propose a new classification which is based on DNA homology. In agreement with this revised classification, the L. lactis subsp. lactis and L. lactis subsp. cremoris strains from our collection have distinct phage sensitivities.

Journal Article↗
PubMed1992

Histidine biosynthesis genes in Lactococcus lactis subsp. lactis.

The genes of Lactococcus lactis subsp. lactis involved in histidine biosynthesis were cloned and characterized by complementation of Escherichia coli and Bacillus subtilis mutants and DNA sequencing. Complementation of E. coli hisA, hisB, hisC, hisD, hisF, hisG, and hisIE genes and the B. subtilis hisH gene (the E. coli hisC equivalent) allowed localization of the corresponding lactococcal genes. Nucleotide sequence analysis of the 11.5-kb lactococcal region revealed 14 open reading frames (ORFs), 12 of which might form an operon. The putative operon includes eight ORFs which encode proteins homologous to enzymes involved in histidine biosynthesis. The operon also contains (i) an ORF encoding a protein homologous to the histidyl-tRNA synthetases but lacking a motif implicated in synthetase activity, which suggests that it has a role different from tRNA aminoacylation, and (ii) an ORF encoding a protein that is homologous to the 3'-aminoglycoside phosphotransferases but does not confer antibiotic resistance. The remaining ORFs specify products which have no homology with proteins in the EMBL and GenBank data bases.

Amino Acid Sequence↗
PubMed1990

[Multiple agenesis and prosthetic restoration].

Cases of multiple agenesia present some difficulties in the treatment planing. Three situations may be encountered: limited agenesia, restored by a fixed, bonded or cemented prosthesis, multiple uni- or bimaxillary agenesia without remaining of deciduous teeth, restored by a fixed, bonded or cemented prosthesis or the partial adjacent prosthesis, multiple uni- or bimaxillary agenesia with remaining of deciduous teeth, restored by means of a supra-dental prosthesis. The first two situations have been described in dental literature and are relatively easy to treat. The same is not true for the third situation, where the decision to keep the temporary teeth considerably increases the difficulty of prosthetic restoration. This subject will be illustrated by the presentation of a clinical case of multiple bi-maxillary agenesia. The patient has: on the maxilla: an absence of 9 permanent teeth (18, 15, 14, 12, 22, 23, 24, 25, 28) and the presence of 4 deciduous teeth (62, 63, 64, 65), on the mandible: an absence of all permanent teeth, with the exception of 36 and 46, and the remaining of 4 deciduous teeth (75, 73, 83, 84). The remaining of deciduous teeth and the presence of a very high inter-arch space led to opting for dental coverage so as to keep the deciduous teeth and a proper vertical dimension. The patient wished to solve his "problem" in the maxilla first, and is not wanting to undergo the extraction of his deciduous teeth. The following therapeutic proposal was adapted: On the maxilla, a three-step procedure: first step: building of metal copings on 13, 16 and 26 and metal-ceramic crowns on 11 and 21, second step: building of telescop crowns on 16 and 26 and clasps on 13, 11 and 21, third step: casting of the removable partial denture framework and soldering to the telescop crowns and clasps. On the mandible, a provisional restoration using a supra-dental resin removable partial denture with ceramic occlusal surfaces was adopted. The aesthetic and functional improvement, as well as the comfort provided to the patient due to this kind of mixed prosthesis, appeared to be satisfactory.

Adult↗
PubMed1989

Product of the Lactococcus lactis gene required for malolactic fermentation is homologous to a family of positive regulators.

Malolactic fermentation is a secondary fermentation that many lactic acid bacteria can carry out when L-malate is present in the medium. The activation of the malolactic system in Lactococcus lactis is mediated by a locus we call mleR. Induction of the genes necessary to perform malolactic fermentation occurs only in bacteria with a functional copy of mleR. The mleR gene consists of one open reading frame capable of coding for a protein with a calculated molecular mass of 33,813 daltons. The amino acid sequence of the predicted MleR gene product is homologous to that of positive activators in gram-negative bacteria: LysR, IlvY gene products of Escherichia coli, MetR, CysB of Salmonella typhimurium, AmpR of Enterobacter cloacae, NodD of Rhizobium sp., and TrpI of Pseudomonas aeruginosa.

Amino Acid Sequence↗
PubMed1988

Role of malolactic fermentation in lactic acid bacteria.

Although decarboxylation of malate to lactate by malolactic enzyme does not liberate biologically available energy (e.g., ATP, NADH), the growth rate of many malolactic bacteria is greatly enhanced by malolactic fermentation. The deacidification of the medium due to malate dissipation cannot fully account for this situation. The chemiosmotic theory postulates that another form of energy could generated by translocation of protons through the membrane coupled to end-product efflux. Konings et al. showed that this theory is indeed applicable to lactate efflux in Streptococcus cremoris at pH 7.0. A similar mechanism could account for the observed increased activity in malolactic bacteria. The study in wild type and mutant strains of Streptococcus lactis unable to carry out malolactic fermentation led us to the following conclusions: (1) under glucose non-limiting conditions, malolactic fermentation helps to maintain pH of the medium at a certain level; (2) during glucose limited growth, malolactic fermentation could be coupled with an energetic process independent from that mentioned above.

Energy Transfer↗
PubMed1988

[Malignant non-Hodgkin's lymphoma of tracheo-bronchial sites].

The case of a 66 years old male patient with multiple tracheal and bronchial lesions of non-Hodgkin lymphoma is reported. This was a disseminated form of low-malignancy lymphoma, as shown by histological findings. The lesions disappeared after 10 courses of chemotherapy, and no sign of recurrence was observed during a 3 years' follow-up. It is concluded that the prognosis of this disease depends on histology rather than on anatomical spread.

Aged↗
PubMed1986

Bronchoscopic cryotherapy for airway strictures caused by tumors.

This study reports an application of cryosurgery for the treatment of tracheobronchial tumors. Bronchoscopic cryotherapy can be applied in patients who are not candidates for other traditional therapy. The technique utilizes a nitrous oxide cryoprobe, introduced through a rigid bronchoscope. The principal feature of this probe is to be nonrigid. The cryodestruction is controlled by an impedance metric method. The study group consisted of 27 patients ranging in age from 39 to 88 years. The most frequent diagnosis was squamous cell carcinoma (14). For malignant tumors, the objective was obtained in 13 cases out of 21. Cryotherapy successfully destroyed five benign granulomas. Four or six days after cryotherapy, bronchial biopsy specimens usually showed a necrotic substance, and tumoral tissues were entirely destroyed. The time of survival is probably extended and the quality of life bettered. Most visible tumors are now reached with a flexible cryoprobe, inserted in a flexible bronchoscope.

Adenocarcinoma↗
PubMed1985

Fluorescence as a guide to bronchial biopsy.

The presence of fluorescence was assessed in 34 unselected patients undergoing bronchoscopy, 11 of whom suffered from bronchial carcinoma. Bronchoscopic inspection was carried out with white light and then repeated with blue light after the injection of 2 ml of 10% sodium fluoresceinate. Fluorescence was graded visually. Seventy six pairs of biopsy specimens were obtained. Of 38 specimens from non fluorescent areas, histological appearances were normal in 34. Slight inflammation was observed in three biopsy specimens, and in one there was evidence of tumour even though the specimen was obtained some distance from the primary tumour. Of 38 biopsy specimens from fluorescent areas, histological examination showed appearances of moderate inflammation in 10, severe inflammation in 10, tuberculosis in one, and carcinoma in 11. In six instances histological appearances were normal. Five normal subjects who were smokers were also examined by the same technique. Appearances of metaplasia were found more often in areas showing fluorescence than in areas not showing fluorescence. Bronchial fluorescence is considered to be related to alteration in vascularity and is not specific for carcinoma. The most fluorescent areas are generally the most pathological and visible tumour is very fluorescent, but moderate degrees of fluorescence are difficult to interpret. Biopsy of every fluorescent area seems excessive.

Adult↗
PubMed1985

[Anatomopathology, physiopathology and treatment of the emphysematous disease of infants (apropos of an experience with 133 surgically treated cases)].

Infantile and childhood lobar pulmonary emphysema (LPE) has finally become a rather straightforward problem after 28 years experience and the important statistics published. Contrary to adult emphysema, and leaving aside the particular aspects of causal lesions, the pediatric form is usually a unilateral lobar or infralobar disorder, and therefore lends itself to surgical treatment.

Adolescent↗
PubMed1981

[Detection of malignant melanoma metastases. Value of radioisotopic methods (author's transl)].

No single radioisotopic exploration is capable of detecting metastases of malignant melanomas, but the successive use of three different scintigraphic techniques (liver, bone and 67Ga citrate) has increased the detection rate from 55 to 68%. Since these metastases are small and may develop anywhere in the body, several methods must systematically be combined, particularly when one of them gives normal results. Experience has shown that 13% of metastases would have passed unnoticed if the three scintigraphic techniques had not been used.

Bone and Bones↗
PubMed1981

[Carcinoma of the upper respiratory and digestive tracts. Histopathology and chemotherapy in 300 cases (author's transl)].

The pathological review of 300 larynx hypopharynx and pyriform sinus carcinoma was done systematically. The results expressed according to the absence or the type of chemotherapy (Bleomycine alone or O.M.B. association) are analysed. There is no difference for the epithelial proliferation but the collagenous part of stroma was enhanced by therapeutic. The foreign body granulomas are related to the tumor maturation (keratinization).

Antineoplastic Agents↗
PubMed1981

[Simultaneous or successive locations carcinomas of head and neck (author's transl)].

204 simultaneous or successive locations of carcinoma were observed and analysed in a series of 1992 cases of head and neck carcinomas for 15 years (10.24 p. 100). Simultaneous carcinomas appeared electively in single anatomical area: hypopharynx, oropharynx, endolarynx. Successive carcinoma on the other hand are developed in adjacent anatomical sites. An oesophagal location worsens the prognosis; the related facts and rules are analysed for their frequency. An early detection II counselled and their pathogenesis is discussed.

Adult↗