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S Noël

Publications and source records attributed to S Noël.

17 recordsLinked to original sources
PubMed2001

Molecular detection of Y chromosome microdeletions: an Irish study.

The region of the Y chromosome most critical for male fertility is called the azoospermia factor (AZF) region and it is located within subintervals five and six on the long arm of the Y chromosome. Several genes, all residing here, contribute to spermatogenesis and deletions in these genes are thought to be pathogenetically involved in some cases of male infertility associated with azoospermia or oligozoospermia. The aim of this study was to establish the prevalence of microdeletions in the AZF region of the Y chromosome in an Irish male population undergoing fertility treatment. To do this, we applied and compared two independent polymerase chain reaction (PCR) based screening methods, namely, a PCR protocol using several sequence-tagged site (STS) primer sets and a recently published multiplex PCR Y chromosome screening protocol. A total of 78 patients, attending the IVF unit at University College Hospital, Galway, were included in this study. Of them, 56 suffered from idiopathic azoospermic/oligozoospermic infertility. The remaining 22 patients had various conditions, which may have contributed to their infertility. A total of 50 age-matched normospermic men were included as controls. Two microdeletions were found; one in the AZFa region and one in AZFb region. These deletions were observed among the truly idiopathic cases. Further analysis was performed to study the extent of the deletions and it was confirmed that each deletion encompassed the respective AZF region including the AZF candidate gene.

Adult↗
PubMed2000

Trypanosoma cruzi: infectivity of clonal genotype infections in acute and chronic phases in mice.

Eight Trypanosoma cruzi stocks pertaining to the clonal genotypes 19/20, 32, and 39 have been characterized for three experimental parameters of infectivity in Balb/c mice: (i) percentage of mice with a patent parasitemia (% MPP), (ii) maximum parasitemia (MP), and (iii) percentage of mice with positive hemoculture (% MPH). By order of decreasing values, the values recorded for the clonal genotypes ranked as follows: 19/20, 32, and 39, except for the % MPP parameter, for which 19/20 and 32 were not statistically different. The rate of successful reisolation after infection in mice, analyzed by multilocus enzyme electrophoresis and random amplified polymorphic DNA typing, was statistically different according to the clonal genotype and was different for uniclonal infections and for mixed infections by two different clonal genotypes. These results confirm that T. cruzi clonal genotypes differ significantly in their infectivity in mice.

Acute Disease↗
PubMed1999

Kinetic evidence for the formation of a Michaelis-Menten-like complex between horseradish peroxidase compound II and di-(N-acetyl-L-tyrosine).

The formation of a reversible adsorption complex between a dimer of N-acetyl-L-tyrosine [di-(N-acetyl-L-tyrosine), (NAT)2] and horseradish peroxidase (HRP) compound II (CII) was demonstrated using a kinetic approach. A specific KIIm value (0.58 mM) was deduced for this step from stopped-flow measurements. The dimerization of the dipeptide Gly-Tyr was analysed at the steady state and compared with (NAT)2 dimerization [(NAT)2-->(NAT)4]. A saturation of the enzyme was observed for both substrates within their range of solubility. In each case the rate of dimerization reflected the rate-limiting step of compound II reduction to the native HRP (E) (kappcat/Kappm approximately kII-->E). The kappcat values for (Gly-Tyr)2 and (NAT)4 formation were 254 s-1 and 3.6 s-1 respectively. The KappM value of Gly-Tyr was 24 mM. It was observed that the value (0.7 mM) for (NAT)2 was close both to its specific KIIm value for the second step of reduction (CII-->E) and to its thermodynamic dissociation constant (Kd=0.7 mM) with the resting form of the enzyme. As (NAT)2 was a tighter ligand but a poorer substrate than Gly-Tyr, a steady-state kinetic study was performed in the presence of both substrates. A kinetic model which includes an enzyme-substrate adsorption prior to each of the two steps of reduction was derived. This one agreed reasonably well with the experimental data.

Adsorption↗
PubMed1999

Release of deuterated nonenal during beer aging from labeled precursors synthesized in the boiling kettle.

The use of labeled nonenal enabled the demonstration that the appearance of the cardboard flavor in finished beer comes from lipid auto-oxidation during wort boiling and not from lipoxygenasic activity during mashing. Free trans-2-nonenal produced by linoleic acid auto-oxidation in the kettle disappears, owing to retention by wort amino acids and proteins. This binding linkage protects trans-2-nonenal from yeast reduction but is reversible, allowing release of the compound at lower pH during aging. Labeled trans-2-nonenal is detected after aging when deuterated precursors form in the boiling kettle. The amount of alkenal released correlates with the concentration of reversible associations in the pitching wort. This work brings new illumination to the formation of trans-2-nonenal and overturns many previous hypotheses. It also explains why a reduction in the beer pH intensifies the cardboard flavor.

Aldehydes↗
PubMed1999

A phylogenetic analysis by multilocus enzyme electrophoresis and multiprimer random amplified polymorphic DNA fingerprinting of the Leishmania genome project Friedlin reference strain.

We have assessed the phylogenetic status of the Leishmania genome project Friedlin reference strain by MLEE and multiprimer RAPD including a set of 9 stocks representative of the main Leishmania species and of the whole genetic diversity of the Leishmania genus. To our knowledge, the detailed genetic characterization of the Friedlin strain has never been published before. As previously recorded (Tibayrenc et al. 1993), MLEE and RAPD data gave congruent phylogenetic results. The Friedlin reference strain was definitely attributed to Leishmania (Leishmania) major Yakimoff et Schokhor, 1914. Five specific RAPD patterns made it possible to distinguish between the Friedlin strain and the 2 other L. (L.) major stocks included in the study. Various specific MLEE and RAPD characters permitted to distinguish between the Leishmania species included in the study. All these characters are usable to detect accidental laboratory mix-ups involving the Friedlin reference strain. In confirmation with previous studies involving a more limited set of genetic markers, the general genetic diversity of the Leishmania genus proved to be considerable. It must be made clear that only one strain cannot be considered as representative of the whole genetic variability of the genus Leishmania. In the future, it is therefore advisable to complement the results obtained in the framework of the Leishmania genome project with data from other strains that should be selected on a criterion of important genetic differences with the Friedlin strain.

Animals↗
PubMed1998

A phylogenetic analysis of the Trypanosoma cruzi genome project CL Brener reference strain by multilocus enzyme electrophoresis and multiprimer random amplified polymorphic DNA fingerprinting.

We have assessed the phylogenetic status of the Trypanosoma cruzi Genome Project CL Brener reference strain by multilocus enzyme electrophoresis (MLEE) and multiprimer random amplified polymorphic DNA (RAPD) including a set of cloned stocks representative of the whole genetic diversity of T. cruzi. MLEE and RAPD data gave congruent phylogenetic results. The CL Brener reference strain fell into the second major phylogenetic subdivision of T. cruzi, and was genetically very close to the Tulahuen reference strain. No reliable RAPD character and only one MLEE character permitted us to distinguish between the CL Brener and Tulahuen reference strains. In contrast, many RAPD and MLEE characters were able to distinguish between the CL Brener reference strain and the other T. cruzi genotypes analyzed here, in particular the formerly described principal zymodemes I, II and III. It is suspected that both CL Brener and Tulahuen are hybrid genotypes, a fact that should be taken into account when interpreting sequence data. Moreover, our study confirms that the species T. cruzi is genetically very heterogeneous. We recommend future comparison of sequencing data from the CL Brener reference strain with those of at least one radically distinct T. cruzi genotype, belonging to the other major phylogenetic subdivision of this species.

Animals↗
PubMed1998

Trypanosoma cruzi: impact of clonal evolution of the parasite on its biological and medical properties.

Trypanosoma cruzi populations are subdivided into natural clones that can exhibit considerable genetic differences. It has been proposed that T. cruzi clonal structure has a major impact on this parasite's biological properties. The present work aims at testing this hypothesis. Twenty-one stocks isolated from various ecological cycles, places, and hosts were characterized by multilocus enzyme electrophoresis (MLEE) with 22 genetic loci and random amplification of polymorphic DNA (RAPD) with 10 primers on the one hand and by 14 different biological parameters on the other hand. These parameters were related to: (i) growth kinetics of epimastigotes and amastigotes; (ii) infection of culture cells by amastigotes; (iii) viability of extracellular trypomastigotes; or (iv) sensitivity of epimastigotes, trypomastigotes, and amastigotes to Benznidazole and Nifurtimox. MLEE and RAPD results exhibited parity to each other, as previously noted (M. Tibayrenc, K. Neubauer, C. Barnabé, F. Guerrini, D. Skarecky, and F. J. Ayala, 1993, Proceedings of the National Academy of Sciences of the USA 90, 1335-1339), and showed that the 21 stocks were distributed into three main genetic groups, 19/20, 32, and 39, corresponding to the major clones 19, 20, 32, and 39 previously described on the basis of 15 isozyme loci. Most biological parameters showed a strong correlation to the genetic distances evaluated from either MLEE or RAPD, which favors the working hypothesis. The only exception came from drug sensitivity estimated on trypomastigote forms. The overall results made it possible to firmly reject the null hypothesis that there is no relationships between evolutionary distances and biological differences in T. cruzi natural clones.

Animals↗
PubMed1998

Trypanosoma cruzi: compared vectorial transmissibility of three major clonal genotypes by Triatoma infestans.

Twenty Trypanosoma cruzi stocks attributed to the 19/20, 32, and 39 major clones (Tibayrenc et al. 1986) were used to infect experimentally third instar larvae of Triatoma infestans. Three variables were considered: (i) percentage of infected insects; (ii) number of flagellates per insect (NFI); and (iii) percentage of metacyclic trypomastigotes per insect. Differences between the genotypes under study for all parameters considered were detected. These differences were statistically significant (P < 10(-3)), except between the 39 and 32 clonal genotypes for the NFI parameter. The correlation coefficient between the genetic distance and the biological parameters determined by the nonparametric Mantel's test was strongly significant (P < 10(-4)). Data obtained suggest clearly that populations of parasites belonging to the 19/20 genotype are more efficiently transmitted (high transmissibility genotype) by the vector than the 32 genotype (low transmissibility genotype), while the 39 genotype presents intermediary characteristic. Results confirm the working hypothesis that the subdivision of T. cruzi into discrete clonal lineages has an impact on the vectorial competence of T. infestans, the most important vector of the chagasic infection in South America, and that different clonal lineages do not exhibit the same vectorial transmissibility. This fact is relevant both for Chagas' disease epidemiology and for the use of xenodiagnosis.

Animals↗
PubMed1998

Compared vectorial transmissibility of pure and mixed clonal genotypes of Trypanosoma cruzi in Triatoma infestans.

A total of 15 mixtures involving 9 different stocks attributed to the 19/20, 32 and 39 major clonal genotypes of Trypanosoma cruzi were used to infect third-instar nymphs of Triatoma infestans via an artificial feeding device. Three biological parameters were considered: (1) the percentage of infected insects (%II), (2) the number of flagellates per insect (NFI), and (3) the percentage of trypomastigotes per insect (%DIF). Genetic characterization by both multilocus enzyme electrophoresis (MLEE) and random amplification of polymorphic DNA (RAPD) indicated that in almost all cases (87%), mixtures remained present after completion of the whole cycle in the insect vector. Two lines of comparison were performed: (1) pure clonal genotypes versus corresponding mixed clonal genotypes and (2) the actual behavior of mixed clonal genotypes versus the expected behavior of the theoretical mixture (i.e. the arithmetic mean of the results observed for each of the two clonal genotypes taken separately). Statistical analyses of the variables were made difficult because of the presence of large standard deviations. Nevertheless, in several cases, mixtures differed significantly from pure clonal genotypes, and in one case the actual mixture differed significantly from the theoretical mixture. In some cases, interaction (either potentialization or reciprocal inhibition) could be suspected.

Animals↗
PubMed1998

The gp63 gene locus, a target for genetic characterization of Leishmania belonging to subgenus Viannia.

In the present study the gp63 gene locus was used as a target for genetic characterization of Leishmania parasites by 2 methods: (i) RFLP analysis with several restriction enzymes (gp63-RFLP), and (ii) intra-genic PCR amplification coupled with restriction analysis (PCR-RFLP). Both methods were applied to a large number of natural isolates belonging to 4 species of the subgenus Viannia, namely L. (V.) braziliensis, L. (V.) peruviana, L. (V.) guyanensis and L. (V.) lainsoni; reference stocks of subgenus Leishmania were included as outgroups. Multilocus isoenzyme typing (MLEE) was used as a reference. On the one hand gp63-RFLP evidenced an extensive polymorphism and revealed specific markers for subgenus, species and geographical populations: congruence with MLEE was demonstrated statistically. The particular interest of gp63-RFLP was illustrated by infra-specific polymorphism, because of the possible relationship with phenotype diversity. On the other hand intra-genic amplification was less resolutive than gp63-RFLP, but also allowed discrimination of the 2 subgenera (PCR alone) and all the species tested in the subgenus Viannia (PCR-RFLP). PCR-RFLP presents an important operational advantage as it allows genetic characterization of minute amounts of parasites, using Leishmania specific primers. The polymorphism revealed by gp63-RFLP and PCR-RFLP illustrates the very high genomic and genetic plasticity of gp63 genes.

Animals↗
PubMed1992

Movement disorders due to cerebral Toxoplasma gondii infection in patients with the acquired immunodeficiency syndrome (AIDS).

Hemichorea and parkinsonism are unusual manifestations of cerebral toxoplasmosis in patients with AIDS. We here describe two such cases and we reviewed extensively the literature (through computer searches using MEDLINE) for other reported instances. In our patients, unlike the other neurological symptoms, the response of the movement disorders to anti-toxoplasmosis therapy was delayed and only partial. We demonstrate that tetrabenazine is a valuable additional symptomatic treatment for choreic movements in one of our patients. We emphasize that, among patients suffering from AIDS, particularly in countries with high prevalence of toxoplasmosis, the occurrence of movement disorders should first suggest the diagnosis of cerebral toxoplasmosis.

Acquired Immunodeficiency Syndrome↗
PubMedDate not supplied

Is Leishmania (Viannia) peruviana a distinct species? A MLEE/RAPD evolutionary genetics answer.

A set of 38 Leishmania stocks from the Andean valleys of Peru was characterized by both Multilocus Enzyme Electrophoresis (MLEE) and Random Amplified Polymorphic DNA (RAPD). Data were analyzed in terms of taxonomy and evolutionary genetics. Synapomorphic MLEE and RAPD characters, clear-cut clustering, and strong agreement between the phylogenies inferred from either MLEE or RAPD supported the view that Leishmania (Viannia) peruviana and Leishmania (Viannia) braziliensis correspond to two closely related, but distinct monophyletic lines (clades) and can therefore be considered as "discrete typing units" (DTUs). The question whether the L. (V.) peruxviana DTU deserves species status is dependent upon the desirability of it, in terms of epidemiological and medical relevance. A previous Orthogonal Field Alternating Gel Electrophoresis (OFAGE) analysis of the same L. (V.) peruviana isolates was published by Dujardin et al. (1995b). The data from the different markers (i.e. MLEE, RAPD and OFAGE) were compared by population genetics analysis. RAPD and OFAGE provided divergent results, since RAPD showed a strong linkage disequilibrium whereas OFAGE revealed no apparent departure from panmictic expectation. MLEE showed no linkage disequilibrium. Nevertheless, contrary to OFAGE, this is most probably explainable by the limited variability revealed by this marker in L. (V.) peruviana (statistical type II error). RAPD data were consistent with the hypothesis that the present L. (V.) peruviana sample displays a basically clonal population structure with limited or no genetic exchange. Disagreement between RAPD and OFAGE can be explained either by accumulation of chromosomal rearrangements due to amplification/deletion of repeated sequences, or by pseudo-recombinational events.

Animals↗
PubMedDate not supplied

[Vasculitis of the central nervous system].

The involvement of the central nervous system (CNS) by a vasculitic process is an infrequent but serious manifestation of several systemic diseases. The neurological disturbances are most often due to cerebral ischemia; however, vascular inflammation is not the only pathogenetic factor of CNS disease in systemic vasculitis. Most often, the specific diagnosis of CNS vasculitis depends on identifying clinical or histologic evidence of target organ involvement outside the CNS. The primary angiitis of the central nervous system (PACNS) is a rare form of vasculitis limited to the central nervous system. The diagnosis of this disorder is difficult owing to its various clinical manifestations and to the poor specificity of the neurological investigations. The demonstration by cerebral angiography and/or tissue examination of an arteritic process is mandatory for establishing this diagnosis.

Biopsy↗
PubMedDate not supplied

Auriculo-ventricular block and distal myopathy with rimmed vacuoles and desmin storage.

A young patient had an auriculo-ventricular block and a distal myopathy with muscle biopsy findings suggestive of inclusion body myositis. What was most unusual was the presence of numerous sarcoplasmic bodies identified as desmin by electron microscopy and immunocytochemistry. The nosological situation of this condition is discussed.

Child↗