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Biomedical subjects

F Renaud

Publications and source records attributed to F Renaud.

At least 91 records · Page 5Linked to original sources
PubMed1993

[Absence of distinctive characteristics between Staphylococcus epidermidis strains responsible of non-hospital infectious endocarditis and commensal strains].

In order to recognize particular characteristics of pathogenic strains, epidemiologic markers of 27 Staphylococcus epidermidis strains (9 pathological and 18 commensal) were studied. Nine strains were responsible of infective endocarditis (8 on native valves, and 1 on prosthetic valve). No case occurred after admission to hospital or surgery. Eighteen commensal strains were isolated from control subjects who had had no contact with the hospital environment and who had not received a recent antibiotic treatment. The microbiological characteristics were so diverse that no differentiation between the pathogenic strains and commensal strains could be done and no particular pathogenic clone was recognized.

Anti-Bacterial Agents↗
PubMed1992

Cloning of two different 5' untranslated exons of bovine acidic fibroblast growth factor by the single strand ligation to single-stranded cDNA methodology.

In an attempt to characterize the 5' UTR of the aFGF mRNAs we used the new anchored PCR methodology, single strand ligation to ss-cDNAs (SLIC). In bovine brain and retina, two kinds of aFGF cDNA clones were isolated. They contained two alternative exons located 34 bp upstream to the translation initiation codon ATG. Taking into account the number of clones specific for each exon, the two mRNAs are expressed with the same ratio in both tissues. One of these bovine 5' UTR exons (136 bp) showed 81% identity to a human 5' UTR exon, the second one (323 bp) was 70% identical to the second human 5' UTR exon with a central region of 90 nucleotides showing 41% identity. The conservation of the splicing positions for these 5' UTR alternate exons in both bovine and human species, suggests that the overall structure of the aFGF gene is conserved in mammals. Furthermore, the conservation of the nucleotide sequences and of the localization of these 5' UTR exons suggests that these non-coding regions may be involved in the control of aFGF gene expression.

Amino Acid Sequence↗
PubMed1992

Heterogeneity of 3'untranslated region of bovine acidic FGF transcripts.

A bovine aFGF genomic clone (14.2 Kb) has been isolated and characterized. This clone contains exons 2 and 3 interrupted by 6.7 Kb long intron. Exon 3 contains part of the coding region and the 3' untranslated region (3'UTR). Two overlapping cDNA clones specific for this 3'UTR have been isolated from bovine retina cDNA libraries or after amplification of RNA by the RACE technique. Analysis of these clones and RNAse protection assay demonstrate alternative termination of aFGF transcripts giving rise to differently sized 3'UTR of 2.5 Kb and at least 3.9 Kb. The sequence of these long 3'UTR is highly conserved among species (70% identity between human and rat) which suggests an important role for aFGF expression.

Amino Acid Sequence↗
PubMed1991

A simple model of host-parasite evolutionary relationships. Parasitism: compromise or conflict?

The evolutionary biology of host-parasite relationships are considered here using a simple game-theory model in which hosts play against parasite and vice versa. In this model, the players can choose between two strategies (aggressive or not aggressive) and the utility of the game is envisaged in terms of fitness and selective costs. The game solutions suggest that the two types of confrontation are encountered in symbiotic relationships and thus constitute two Evolutionary Stable Strategies (ESS). These observations lead us to discuss: (i) the status of different kinds of symbiotic relationships (i.e. parasitoidism; parasitism, commensalism and mutualism) related to selective costs and (ii) the position of coevolution in this game theory context.

Animals↗
PubMed1991

Mechanisms involved in parasitic castration: in vitro effects of the trematode Prosorhynchus squamatus on the gametogenesis and the nutrient storage metabolism of the marine bivalve mollusc Mytilus edulis.

The mechanisms involved in the parasitic castration of the marine mussel Mytilus edulis by the trematode parasite Prosorhynchus squamatus Odhner, 1905, have been investigated in vitro with two bioassays employing dissociated host tissues. There is no conclusive evidence that P. squamatus affects the secretion of two host neuroendocrine factors, viz., gonial mitosis-stimulating factor and glycogen mobilization hormone, involved in the gametogenesis/nutrient storage cycles of the mussel. In contrast, extracts of P. squamatus sporocysts and cercariae significantly stimulated glycogen mobilization in host glycogen cells and strongly inhibited host gonial mitosis. A gonial mitosis-inhibiting factor (GMIF) was found in the hemolymph of parasitized mussels. The existence of an endogenous GMIF in mantle tissue of uninfected mussels has been demonstrated. This factor appeared to be secreted into the hemolymph during the period of sexual maturity. Whether the parasite acts directly on the host gonia, or by provoking the liberation of this endogenous GMIF, has yet to be ascertained. It would appear, however, that the parasite acts directly on host glycogen cells.

Animals↗
PubMed1991

DNA reassociation kinetics and genome complexity of a fish (Psetta maxima: Teleostei) and its gut parasite (Bothriocephalus gregarius: Cestoda).

1. The genomic structure of a fish (Psetta maxima) and of a Tapeworm (Bothriocephalus), who form a close host-parasite association, was determined by reassociation kinetics experiments. 2. Spectrophotometric readings of single-stranded versus double-stranded DNA separated on hydroxylapatite columns after reassociation at Cot values ranging from 0.0001 to 10(5) allowed the drawing of the reassociation curves of both genomes. 3. Different fractions according to their degree of repetitivity were evidenced, and the relative amounts of repetitive versus single-copy sequences, as well as their complexity, were calculated. 4. It appears that the amount of non-repetitive DNA is lower in the Tapeworm than in its vertebrate host, although the complexity of these single-copy sequences is the same.

Animals↗
PubMed1991

Gas-liquid chromatographic analysis of cellular fatty acid methyl esters in Aeromonas species.

The cellular fatty acids of 39 strains belonging to the genus Aeromonas (Aeromonas hydrophila, Aeromonas caviae, Aeromonas sobria, Aeromonas media, Aeromonas schubertii, Aeromonas veronii) were determined by high resolution gas-liquid chromatography. The fatty acid profiles were characterized by major amounts (60% or more) of one saturated (hexadecanoic acid = 16:0) and two unsaturated (hexadecenoic acid = 16:1 and octadecenoic acid = 18:1) acids. While the majority of the strains of the six species exhibited, qualitatively, very similar fatty acid compositions, only minor and inconsistent differences could be observed which would be useful for a distinction of the different taxons. The following fatty acids were qualitatively identified: 12:0, i-13:0, 14:0, 3-OH 13:0, i-15:0, 15:0, 2-OH 14:0, 3-OH 14:0, i-16:0, 16:1, 16:0, i-17:1, i-17:0, a-17:0, 17:0 cyclopropane, 17:1, 17:0, 18:1 (3 isomers), 18:0 and i-20:0. Excellent congruence was found in reproducibility studies. Fatty acid analyses show a great homogeneity within the group and the technique does not appear to be the ideal method in distinguishing between Aeromonas species.

Aeromonas↗
PubMed1991

Differential susceptibility to a trematode parasite among genotypes of the Mytilus edulis/galloprovincialis complex.

We show that parasitism by the trematode Prosorhynchus squamatus in parental and introgressed Mytilus edulis/galloprovincialis (Bivalvia) mussels occurs in individuals with a predominantly M. edulis genome. This result suggests that the restricted specificity of P. squamatus is dependent on genetic factor(s) present in M. edulis. Because of its strong pathogenic effects (i.e. total castration and possible death), this parasite may be a source of intense selection against M. edulis genomes when they are present in a site. As a consequence, it may favour the geographic extension of the M. galloprovincialis genome. Previous studies have indicated that, in hybrid zones, recombinant genotypes are more susceptible to parasitic infections than either parental genotype. We demonstrate that this is not the case for the M. edulis/M. galloprovincialis system, and that the parental genotype alone determines susceptibility.

Alleles↗
PubMed1991

Molecular epidemiology of Staphylococcus haemolyticus strains isolated in an Albanian hospital.

A recent outbreak of erythroderma in young children in an Albanian hospital was investigated. The etiology was not established, but Staphylococcus haemolyticus was frequently isolated from the affected children and from staff working in the same unit. Possible relationships among the isolates were investigated by using classical techniques (biotype, antimicrobial susceptibility, and extrachromosomal DNA pattern) and by restriction endonuclease analysis (REA) of total DNA. Control isolates of proven pathogenicity from hospitalized patients in Lyon, France were subjected to the same procedures. Distinct REA patterns were obtained after digestion with two enzymes in 7 of 10 isolates from five affected children. Six distinct patterns were observed in nine isolates from six staff members; two REA patterns from patient isolates and two from staff members were identical, and these were distinguishable by the other markers examined. Only two different REA patterns were found in the pathogenic control isolates despite the use of a third additional enzyme. Again, the isolates with the same REA patterns could be distinguished by their plasmid profile or antimicrobial resistance profile. REA of total DNA used in combination with other markers indicated that the Albanian isolates differed considerably, whereas the French pathogenic isolates showed little variability.

Albania↗
PubMed1990

Plasmid profiles and genomic DNA restriction endonuclease patterns of 30 independent Staphylococcus lugdunensis strains.

Extrachromosomal DNA analysis and restriction endonuclease analysis of whole cellular DNA were used to characterize 30 Staphylococcus lugdunensis strains isolated from 13 different hospitals from 1977 to 1988. All the strains were susceptible to most of the antibiotics tested, including penicillin G. A single 3.2 kilobase plasmid was detected in 13 strains and one or two plasmids, ranging from 2.3 to 6.6 kilobases, were found in 7 strains. EcoRI, PstI and PvuII restriction patterns of total cellular DNA were identical for 23 isolates, indicating strong conservation of endonuclease sites in this species. One or two additional DNA bands occurred in seven isolates. Molecular markers show rather little variations between different S. lugdunensis isolates suggesting that they are closely related.

DNA Restriction Enzymes↗
PubMed1990

A model for studying isolation mechanisms in parasite populations: the genus Lepeophtheirus (Copepoda, Caligidae).

In the Mediterranean, the parasitic copepod Lepeophtheirus thompsoni Baird, 1850 specifically infests turbot (Psetta maxima L., 1758), whereas L. europaensis Zeddam, Berrebi, Renaud, Raibaut, and Gabrion, 1988 infests brill (Scophthalmus rhombus L., 1758) and flounder (Platichthys flesus L., 1758). Experimental infestation of turbot by copepods from each of the three fish species showed an absence of any physiological incompatibility preventing natural development of the two parasite species, at least on one host species, i.e., the turbot. Moreover, interspecific hybrids were obtained experimentally, which implies that 1) there is no strict genetic barrier between the two species and 2) the natural prezygotic isolation results from a choice of the most favorable habitat. We discuss the origin and possible consequences of the presence, in the Mediterranean, of L. europaensis on brill and flounder, two hosts separated by their taxonomic status and ecobiology.

Animals↗
PubMed1990

Instability of characteristics amongst coagulase-negative staphylococci causing endocarditis.

Variation in typing of clinically significant isolates of coagulase-negative staphylococci (CNS) was determined by five typing methods with 143 isolates obtained from 19 patients over periods from 2 days to 1 year. In only one case did all isolates give exactly the same typing pattern by all five tests. No single method, or simple combination, provided a ready means of confirming the relatedness of separate isolates. The most frequently useful tests were antibiotic susceptibility and extrachromosomal DNA banding patterns. However, the results of biotyping, serotyping and phage typing were also helpful in showing the relationship between different isolates from a given patient. In most cases a core pattern varying by the gain or loss of a small number of features, characterised a given patient's isolates. In two causes, apparently radical changes in the infecting organism were observed, and confirmed by restriction endonuclease analysis. Care should be taken when successive isolates of CNS show distinct typing differences in deciding their clinical relevance.

Anti-Bacterial Agents↗
PubMed1990

[Comparison of two systems for identifying coliform enterobacteria newly described or rarely found in clinical practice].

The API 20 EC and ATB 32 GN identification systems were compared for their ability to identify 231 coliform bacteria strains. Agreement with the identification given by conventional methods was achieved for 96.1 p. cent of strains by the API 20 EC gallery and for 95.9 p. cent by the ATB 32 GN system. Complementary tests were needed to identify 9.5 p. cent of strains using the API 20 EC system but 30.3 per cent using the ATB 32 GN system.

Bacteriological Techniques↗
PubMed1989

Effect of passive transfer of human anti-myelin-associated glycoprotein IgM in marmoset.

Adult and one week old marmosets were injected intravenously within a one month period or intraperitoneally within a 6 week period respectively, with monoclonal IgM having an anti-myelin associated glycoprotein antibody activity. No clinical or electrophysiological abnormalities could be detected in experimental animals. However, indirect immunofluorescence studies showed IgM deposition in close contact to myelin sheaths. Minor but distinct alterations of nerves were found in the adult: the enlargement of Schmidt-Lanterman incisures seen in electron microscopy could explain the decrease of the proportion of fibers of small diameter found by morphometry of semi-thin section, and the reduction of the mean internodal length in fibers of a given diameter seen in teased nerve fibers studies.

Animals↗
PubMed1988

Carbon substrate assimilation patterns of clinical and environmental strains of Aeromonas hydrophila, Aeromonas sobria and Aeromonas caviae observed with a micromethod.

The assimilation of carbon substrates by 103 strains of Aeromonas of different origin identified by conventional methods was studied by means of a standardized micromethod containing 147 tests (API system). Six distinct groups could be recognized and the discriminating substrates were determined. 3 species of Aeromonas can be identified by means of conventional method: A. hydrophila, A. sobria and A. caviae. The method has a number of drawbacks: Some media are unreliable, others are difficult to read, strict preservation conditions are essential. The proposed micromethod for carbon substrate assimilation allows, in most cases, a simple separation of the 3 motile Aeromonas species.

Aeromonas↗
PubMed1988

Speciation of cestoda. Evidence for two sibling species in the complex Bothrimonus nylandicus (Schneider 1902) (Cestoda: Cyathocephalidea).

Using biochemical genetic methods, we have distinguished 2 sibling species in the complex Bothrimonus nylandicus (Schneider, 1902), which infest 2 congeneric species of sole (Solea lascaris and Solea impar) on European coasts (Atlantic and Mediterranean). Neither of the parasite species is specific for either of the sole species, but one of them is present all year round, whereas the other is absent in the autumn and winter and only appears in the spring, subsequently disappearing at the end of the summer. Only S. impar lives in the Mediterranean, and is equally infested by both cestodes, whereas both species occur in the Atlantic and each of them is preferentially infested by 1 species of cestode. The shortness of the adult stage of the parasite in the definitive host and the presence of 2 life-cycles associated with competition between the 2 hosts in the Atlantic could be responsible for the biological differences observed and for maintaining the sibling species in sympatry.

Animals↗