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J Elion

Publications and source records attributed to J Elion.

At least 91 records · Page 5Linked to original sources
PubMed1994

Differentiation of Escherichia coli strains using randomly amplified polymorphic DNA analysis.

Fifty-nine Escherichia coli strains isolated from 54 unrelated patients over a six-year period, as well as the reference strain of the species, were studied by analysis of randomly amplified polymorphic DNA (RAPD) to assess the usefulness of this genotyping approach in molecular epidemiology. Using a 10-mer oligonucleotide primer, 28 different RAPD fingerprints were distinguished among the 60 strains previously delineated in 36 ribotypes by EcoRI and HindIII digests. The patterns were reproducible and stable after in vitro and in vivo studies. Some strains harbouring an identical ribotype exhibited distinct RAPD fingerprints. Thus, these data illustrate the usefulness of the association of two genetic markers in assessing the relationship between strains. Interestingly, among the RAPD patterns, several bands were present only in the highly virulent carboxylesterase type B2 strains, which are more homogeneous than the carboxylesterase type B1 strains. Because of its simplicity and rapidity, RAPD analysis appears to be a highly valuable tool for studying E. coli molecular epidemiology.

Bacteremia↗
PubMed1994

Genetic heterogeneity of Pseudomonas aeruginosa clinical isolates revealed by esterase electrophoretic polymorphism and restriction fragment length polymorphism of the ribosomal RNA gene region.

The intra-species differentiation of Pseudomonas aeruginosa was analysed by comparing the polymorphism of esterases by conventional polyacrylamide-agarose gel electrophoresis, the physicochemical properties of the variants of the major esterase P3 and the restriction fragment length polymorphism of ribosomal RNA gene regions (ribotyping) to O-serotyping for several panels of strains selected from among a series of 257 clinical isolates and two references strains, (ATCC nos. 10145 and 27853). The electrophoretic variation of four main kinds of esterase (P1-P4) and 11 additional esterases distinguished by their spectra of hydrolytic activity with synthetic substrates and by their sensitivity to di-isopropylfluorophosphate, allowed the discrimination of 67 zymotypes. Thirty-two esterase P3 variants were characterized by their pI, electrophoretic mobilities and titration curve analyses. They were distributed into two groups which, by these molecular criteria, seem to be distantly related. Combination of the patterns resulting from HindIII, EcoRI and BclI restriction endonuclease digestions allowed the discrimination of 33 ribotypes among 134 strains. The strains exhibiting esterase P3 variants of group 2 presented a distinct ribotype and belonged to serotype (O)12. They could constitute a distinct group within the species. For the majority of the strains, the absence of correlation between zymotype, ribotype and serotype argues for a high level of heterogeneity within P. aeruginosa and indicates that the parallel use of the first two methods represent a potential tool for epidemiological study.

DNA, Ribosomal↗
PubMed1994

An improved DNA-based identification of fetuses at risk for HPA-1a (PlA1) neonatal alloimmune thrombocytopenia.

A simple and reliable procedure, based on DNA amplification and HpaII mapping, is proposed for the identification of fetuses at risk for HPA-1a (PlA1) neonatal alloimmune thrombocytopenia which could cause life-threatening haemorrhage, even in early fetal life. This typing procedure for HPA-1 alleles should help in deciding, very early, the therapeutic management of the fetuses at risk.

Antigens, Human Platelet↗
PubMed1994

Use of ribotyping in epidemiological surveillance of nosocomial outbreaks.

Over the past few years, genotypic methods based on the study of bacterial DNA polymorphism have shown high discriminatory power for strain differentiation and superiority over most phenotypic methods commonly available in the clinical microbiology laboratory. Some of the methods used, however, required either a high level of technology and sophisticated equipment (e.g., pulsed-field gel electrophoresis) or species-specific reagents of restricted availability (randomly cloned DNA probes or gene-specific probes). Because ribotyping uses a universal probe (rRNA) and is a rather simple technology, particularly since the advent of nonradioactive labelling systems, it has been widely used for strain differentiation of most bacterial species involved in nosocomial outbreaks. In vitro and in vivo stability of the markers studied has been demonstrated. Although there may be limitation to this approach, ribotyping was found to be highly discriminative, particularly for typing members of the family Enterobacteriaceae, Pseudomonas cepacia, and Xanthomonas maltophilia. In many cases, it has improved the understanding of the mechanism of nosocomial acquisition of organisms by allowing a distinction between endogenous and exogenous infections. Among exogenous infections, it has distinguished between individual and epidemic strains, thus differentiating cross-infection from independent acquisition.

Bacteria↗
PubMed1994

Fetal haemoglobin variations following hydroxyurea treatment in patients with cyanotic congenital heart disease.

Haematological features of 64 patients suffering from non operable cyanotic congenital heart disease (CCHD) treated with hydroxyurea (HU) were compared with those of 43 patients suffering from the same disorder who had not yet received this drug. Patients with subclinical renal dysfunction were excluded by measuring plasma creatinine levels. MCV and HbF were higher among patients receiving HU, the increase in MCV being cumulative with HU dosage but the rise in HbF dose independent. HbF response to HU was found to be due to the coordinated increase in F-cell and F-reticulocyte production rather than to a selective survival of F-cells. Absence of a relationship between plasma erythropoietin and HbF levels excluded a dominant role of the former in increasing F-cell production and results determined after doubling the HU dosage or immediately after initiating therapy suggested genetic differences to be responsible for the individual variations in Hb F response. No irreversible toxic effects or malignancies were noted in this series of patients. HU was administered for a relatively long period of time, the mean duration of treatment exceeding 5 years, while the study also included patients below the age of 10 years.

Adolescent↗
PubMed1994

HLA-mismatched cord blood transplantation: immunological studies.

Two cases of HLA partially matched related cord blood transplantation were reported. The first patient remains healthy more than 4 years after graft. The second patient died from acute GVHD. In the first case, the immune reconstitution was studied over a 2 year period after graft: the alloreactive cytotoxic T-cell precursor (CTLp) frequencies were comparable between the donor and the recipient. Indirect evidence suggested that the resolution of GVHD was not due to a specific deletion of CTLp against the HLA antigens unshared between donor and recipient.

Child↗
PubMed1994

Anthropological approach to the heterogeneity of beta-thalassemia mutations in northern Africa.

Results of an epidemiological survey for beta-thalassemic defects involving 239 chromosomes in Algeria are analyzed in relation to the geographic and historical background of the country and are compared with published series for the Tunisian population. Four common mutations account for 81% of the chromosomes, but 13 other defects have been found, illustrating the highly heterogeneous nature of the disease in the northern African countries of the Maghreb. The high frequency of homozygous cases reflects the endogamous social structure of these populations. Distribution of the mutations and linkage to specific RFLP haplotypes provide information concerning their origin and date of introduction in good correlation with the anthropological history of Algeria.

Algeria↗
PubMed1994

[Mucoviscidosis discovered after the age of 25 years. Review and follow-up of cases of the literature].

We report a case of cystic fibrosis diagnosed in a 27-year-old man complaining of diarrhoea which was present for 2 years. The diagnosis was suspected upon the association of exocrine pancreatic insufficiency, massive hepatic steatosis, pulmonary infiltrates on chest radiograph, and moderate alterations of pulmonary function tests. It was confirmed by positive sweat tests. Study of the cystic fibrosis gene demonstrated a compound heterozygosity for delta F508 deletion and for mutation W1282X. Diagnosis of cystic fibrosis after the age of 25 is a rare event and the 25 hitherto published case reports are analysed after obtention of more detailed information for the authors. The existence of cases of late diagnosis might be explained by genetic heterogeneity.

Adult↗
PubMed1994

Sequence correction and reassignment of the TaqI polymorphic site in the human inter-gamma-globin gene region, an African-specific marker.

We report here that the assignment of nt 37504 in the human inter-gamma-globin gene region of the HUMHBB locus sequence as a C is incorrect and should be replaced by a T. Accordingly, the polymorphic TaqI site, originally described at position 37503 as an African-specific marker, is actually located at position 37992. A PCR-based assay for this anthropologically important genetic marker is described.

Black People↗
PubMed1993

The absence of correlation between allozyme and rrn RFLP analysis indicates a high gene flow rate within human clinical Pseudomonas aeruginosa isolates.

Two hundred and fifty seven human clinical Pseudomonas aeruginosa strains isolated between 1984 and 1990 in several regions of France, as well as two reference strains, were studied by computer-assisted statistical analysis of the data from their esterase electrophoretic patterns and rrn restriction fragment length polymorphisms. No correlation was found between the two sets of data except for some strains of serotype O12 which, thus, may constitute a distinct group within the species. This absence of correlation indicates a high gene flow rate within human isolates of the P. aeruginosa species. A possible explanation is that, because of an as yet unidentified selective advantage, the esterase loci are a major target for recombinational events. Alternatively, horizontal genetic transfers between strains may have occurred at so high a rate that the clonal structure usually observed in bacterial populations has been disrupted. This study highlights clearly the need for caution in inferring bacterial population structure from any single class of genetic markers.

Esterases↗
PubMed1993

Description and partial characterization of a new Chlamydia-like microorganism.

A new obligate intracellular bacterium which we called 'Z' was isolated as a cell culture contaminant of unknown origin. The organism grew in a variety of cultured cells with a 5-7-day developmental cycle, within cytoplasmic phagosomes, similarly to Chlamydia and some Rickettsia spp. Two alternating developmental forms (elementary bodies and reticulate bodies) were observed by electron microscopy. SDS-PAGE electrophoresis, immunoblotting with chlamydia-specific antibodies, and polymerase chain reaction using chlamydial genus specific primers provided evidence that our bacterium differs significantly from chlamydiae. Further characterization of 'Z' including determination of 16S ribosomal RNA sequences will allow its taxonomic position to be established.

Animals↗
PubMed1993

Inter-ethnic polymorphism of the beta-globin gene locus control region (LCR) in sickle-cell anemia patients.

Sequence polymorphisms within the 5'HS2 segment of human locus control region is described among sickle cell anemia patients. Distinct polymorphic patterns of a simple sequence repeat are observed in strong linkage disequilibrium with each of the five major beta s haplotypes. Potential functional relevance of this polymorphic region in globin gene expression is discussed.

Algeria↗
PubMed1993

Molecular analysis of multiply recurrent meningitis due to Escherichia coli K1 in an infant.

Bacterial DNA polymorphism was used to document the occurrence of three separate episodes of meningitis caused by Escherichia coli K1 in an infant. The methods employed included determination of the restriction fragment length polymorphism of total DNA and of ribosomal DNA regions as well as DNA fingerprinting by the arbitrarily primed polymerase chain reaction. By these three genotypic approaches, the three isolates obtained from the infant's cerebrospinal fluid on days 9, 34, and 70, respectively, were found to share the same patterns, which were different from the patterns of control strains. Thus, these three episodes of E. coli K1 meningitis were due to a single strain. DNA-based typing techniques seem extremely promising as tools to be used in unraveling the complex mechanisms of recurrent meningitis.

DNA, Bacterial↗
PubMed1993

The spectrum of beta-thalassaemia in Algeria: possible origins of the molecular heterogeneity and a tentative diagnostic strategy.

We report here on the final results of an epidemiological survey involving 177 beta-thalassaemic chromosomes in Algeria. Four common mutations account for 86% of the chromosomes, the other ones carrying nine other rare mutations. Combination of these results with those of other smaller regional epidemiological studies indicates the existence of still a wider range of mutations. The nature and frequencies of these mutations, their linkage with RFLP-haplotypes, agree well with the history of the region. Knowledge of this spectrum of mutations enables the design of a diagnosis strategy that takes into account the local economical constraints.

Adolescent↗