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J Elion

Publications and source records attributed to J Elion.

At least 19 recordsLinked to original sources
PubMed1992

Complete sequence of the major outer membrane protein-encoding gene of Chlamydia trachomatis serovar Da.

The complete nucleotide sequence of the gene omp1 encoding the major outer membrane protein (MOMP) of Chlamydia trachomatis serovar Da was determined following amplification by the polymerase chain reaction. The most closely related complete sequence published to date is that encoding the C. trachomatis L1 MOMP. When the L1 and Da MOMP deduced amino acid (aa) sequences were compared, 16 single-aa differences located mostly in the variable domains I, II, and IV were detected. These regions contain the B-cell epitopes. Additional differences were found in the constant domains I and II, thought to participate in the T-cell response.

Amino Acid Sequence↗
PubMed1992

DNA sequence variation in a negative control region 5' to the beta-globin gene correlates with the phenotypic expression of the beta s mutation.

The clinical diversity of sickle cell anemia is strongly related to the degree of intracellular hemoglobin S (Hb S) polymerization, which in turn is dependent on the intracellular concentration of Hb S. We have recently defined a region of DNA approximately 500 bp 5' to the human beta-globin gene that acts as a silencer for the transcription of this gene and have shown that a polymorphism in this sequence is associated with a thalassemic phenotype of the beta-globin gene. In this work we have examined the correlation of DNA sequence polymorphisms in this silencer with binding of a previously identified putative repressor protein, BP1, and with the expression of Hb S in individuals heterozygous for the beta s allele. It was found that specific configurations of the motif, (AT)x(T)y, are homogeneous for the major haplotypes of the beta-globin gene cluster described on beta s chromosomes. Binding of BP1 was measured to DNA of three haplotypes: Indian, Benin, and Bantu. BP1 binds most tightly to DNA of the Indian haplotype, and these patients produce less beta s protein than Benin patients, whose DNA exhibits weaker affinity for BP1. Binding of BP1 is the weakest to DNA of the Bantu haplotype, which is associated with clinically more severe sickle cell symptoms. These data are consistent with the hypothesis that these polymorphisms may not be neutral and that the DNA sequence at this site may affect the expression of the beta s gene. Such an effect may be synergistic with other genetic variables, such as fetal hemoglobin levels, F-cell numbers, and the number of alpha-globin genes, in determining intracellular polymerization and, thus, the severity of the sickle cell syndromes.

Africa↗
PubMed1992

Genetic epidemiology of beta-thalassemia in Sicily: do sequences 5' to the G gamma gene and 5' to the beta gene interact to enhance HbF expression in beta-thalassemia?

The present epidemiological study of the molecular characteristics of beta-thalassemia in Sicily was prompted by the disparate phenotypic expression (in clinical status and absolute HbF level) observed in two beta-thalassemic homozygotes who were also homozygous for the beta-like globin gene cluster haplotype III. We suspected that polymorphisms within haplotype III could be the cause for the discrepancy. Based on the association of particular conformations of the (AT)xT(y) motif (-540 5' to the beta gene) with milder forms of thalassemia and sickle cell anemia, 38 homozygous beta-thalassemia patients were studied to define their haplotypes, the -158 site 5' to the G gamma gene (linked to haplotype III) and the structure of the (AT)xT(y) motif. We found that the patient who was phenotypically mild and homozygous for beta-thalassemia, haplotype III, and the -158 C----T mutation was homozygous for the rare (AT)9T5 motif. In contrast, the patient homozygous for beta-thalassemia, haplotype III, and the -158 mutation, but exhibiting a severe clinical course, was homozygous for the (AT)7T7 configuration. Others have suggested that (AT)9T5 is a negative regulatory protein binding sequence, and it is a silent carrier state for beta-thalassemia. The usual configuration (AT)7T7, has considerably less affinity for regulatory protein binding, and it is the most common configuration in Sicilian beta-thalassemics (67 of the 78 chromosomes studied). Within the 38 patients studied, seven were informative because they had various combinations of the (AT)9T5 and (AT)7T7 motif, and the -158 C----T mutation. The results in these patients suggest that only the co-presence of the (AT)9T5 configuration and a C----T change at -158 5' to the G gamma gene is associated with high HbF expression and a mild clinical phenotype. We postulate that these two regions of the beta-like globin gene cluster interact, when endowed with the proper sequences, to enhance the expression of HbF secondary to anemia.

Adolescent↗
PubMed1992

A novel sickle cell mutation of yet another origin in Africa: the Cameroon type.

The sickle cell mutation (beta s) arose as at least three independent events in Africa and once in Asia, being termed the Senegal, Benin, Bantu and Indian types respectively. An investigation in Cameroon was carried out to determine whether the atypical sickle genes observed in the neighboring countries are the result of recombination or the presence of a sickle cell mutation of a different genetic origin. It was conducted on 40 homozygous SS patients followed at the Blood Transfusion Center in the capital city of Yaoundé. On 80 beta s chromosomes, 13 exhibited a novel polymorphic pattern that was observed three times in the homozygous state. This chromosome contains an A gamma T gene. The restriction fragment length polymorphism haplotype is different from all the other beta s chromosomes in both the 5' and 3' regions, but has previously been reported in sporadic cases. The (AT)8(T)5 sequence in the -500 region of the beta gene is specific and different from that of the Senegal, Benin, Bantu or Indian beta s genes. All the carriers of this specific chromosome belong to the Eton ethnic group and originate from the Sanaga river valley. This observation strongly argues for yet another independent origin of the sickle cell mutation in Africa, here referred to as the "Cameroon type". The Benin haplotype and a Benin/Bantu recombinant haplotype have been observed in the other studied populations: Ewondo, Bamiléké, Bassa, Yambassa and Boulou.

Anemia, Sickle Cell↗
PubMed1992

A haplotype-linked four base pair deletion upstream of the A gamma globin gene coincides with decreased gene expression.

During normal human development, a switch is classically observed in the relative expression of the two gamma globin genes, the G gamma/A gamma ratio varying from 70/30 at birth to 40/60 by the end of the first year. An exception to this developmental pattern is linked to the presence of an XmnI restriction site at a position -158 to the Cap site of the G gamma gene. Another exception is observed in individuals homozygous for two easily detectable variations of the A gamma gene: the presence of a threonine residue at codon 75 and a HindIII site within the second intron. A 4-bp deletion has been described around position -225 in some thalassemic patients presenting with these variations. In this study, we find this deletion to be haplotype-linked in a series of 156 individuals of various ethnic origins and presenting with various normal and pathological phenotypes. In sickle cell patients heterozygous for this 4-bp deletion, the relative expression of the A gamma genes on the two chromosomes can be measured by estimating the A gamma T and A gamma I chains, the former always being synthesized at a lower rate. These results suggest a functional role for the deleted sequence.

Base Sequence↗
PubMed1992

Molecular epidemiological analysis of Pseudomonas aeruginosa strains causing failure of antibiotic therapy in cystic fibrosis patients.

A combination of esterase electrophoretic typing and analysis of the restriction fragment length polymorphism of ribosomal DNA regions (ribotyping) was used to compare 27 Pseudomonas aeruginosa strains isolated before and after two-week courses of anti-pseudomonal treatment in seven cystic fibrosis patients. A total of 12 courses of therapy were studied in which ciprofloxacin, ceftazidime, azlocillin or imipenem were used alone or in combination with tobramycin. Isolates at a count of greater than or equal to 10(6) cfu/ml of sputum were collected when there was evidence of therapeutic failure on the basis of persistence of isolates whether or not they were resistant to the antibiotic used for therapy. Emergence of resistance was observed in ten cases and failure to eradicate sensitive strains in five cases. Among the 27 isolates, eight zymotypes and five ribotypes were identified. With this typing approach, resistant post-therapy isolates were found to be identical to pre-therapy isolates in all cases but one. However, in one case an additional resistant strain was isolated after therapy besides that initially present. In all five cases in which susceptibility was still observed after treatment, pre-therapy and post-therapy isolates were indistinguishable. Using this molecular typing approach, all the strains were typable. Thus combination of esterase typing and ribotyping should improve the analysis of therapeutic failure in cystic fibrosis patients.

Azlocillin↗
PubMed1992

Rapid genotyping shows the absence of cross-contamination in Enterobacter cloacae nosocomial infections.

Restriction fragment length polymorphism analysis (RFLP) of total DNA and rDNA regions was used for the epidemiological evaluation of 10 Enterobacter cloacae nosocomial isolates obtained from nine patients in our hospital. Five of these patients were hospitalized during overlapping periods, thus raising the question of cross-contamination. A single biochemical pattern and antibiotic susceptibility profile was observed for all isolates but one. In contrast, based on the results of total DNA and rDNA RFLP patterns, the genetic unrelatedness of the isolates was clearly shown, thus excluding a common source of contamination or patient-to-patient transfer.

Adult↗
PubMed1992

Extensive study of DRB, DQA, and DQB gene polymorphism in 23 DR2-positive, insulin-dependent diabetes mellitus patients.

To gain insight into the HLA subregions involved in protection against insulin-dependent diabetes mellitus (IDDM) we investigated the polymorphism of HLA-DR and -DQ genes in 23 DR2 IDDM patients. Results show the following. (1) Fourteen patients (61%) possess the DRB1, DRB5, and DQB1 alleles found in DRw16/DQw5 healthy people. These data contrast with the 5% of DRw16 normally found in DR2 populations and are in agreement with former observations supporting that the DRw16 haplotype is not protective. (2) Nine DR2 patients, i.e., 39% versus 95% in published DR2 controls, possess the DRB alleles found in DRw15 unaffected people. Among them, six patients have also DQA1 and DQB1 alleles identical to those found in DRw15/DQw6 healthy individuals. These data confirm that the DRw15/DQw6 haplotype is protective but indicate that none of the DR or DQ alleles, alone or in association, confers an absolute protection. (3) Our most striking results concern the very high frequency of recombinant haplotypes among the DRw15 patients: 3 of 9. In these three patients recombinations led to the elimination of both DQB1 and DQA1 alleles usually associated with DRw15. This strongly suggests that the occurrence of IDDM in these DRw15 patients is due to the absence of the usual DQ product and thus reinforces the assumption that DQ rather than DR region is involved in the protection conferred by the DRw15/DQw6 haplotype. Finally, analysis of the non-DRw15 haplotypes in heterozygous patients showed that IDDM can occur in the absence of any DQ alpha beta heterodimer of susceptibility.

DNA Probes, HLA↗
PubMed1992

Molecular analysis provides evidence for the endogenous origin of bacteremia and meningitis due to Enterobacter cloacae in an infant.

We analyzed the restriction fragment length polymorphism (RFLP) of total DNA and of ribosomal DNA regions (ribotyping) to document the occurrence of endogenous, systemic bacteremia and meningitis due to Enterobacter cloacae in a newborn. Five strains of E. cloacae were isolated from this newborn. Three of these strains were recovered from stool at counts of 10(8), 10(9), and 10(9) organisms/g of feces, respectively; one strain was isolated from blood; and one strain was isolated from cerebrospinal fluid. In addition, five epidemiologically unrelated strains of E. cloacae were studied for comparison. Our study clearly shows the genetic relatedness of the strains isolated sequentially from cultures of stool, blood, and cerebrospinal fluid. RFLP analysis of total DNA and ribotyping seem particularly well suited to the study of the epidemiology of nosocomial E. cloacae strains.

Bacteremia↗
PubMed1992

Mother-to-infant vertical transmission and cross-colonization of Streptococcus pyogenes confirmed by DNA restriction fragment length polymorphism analysis.

Restriction fragment length polymorphism (RFLP) analysis of total DNA and of ribosomal DNA (rDNA) regions (ribotyping) were used to document Streptococcus pyogenes vertical mother-to-infant transmission and to investigate the spread of S. pyogenes in an obstetric unit. Two isolates from a newborn, two isolates from his mother (patient 1), and two isolates from two other mothers (patients 2 and 3) were studied. RFLP of total DNA, both after HindIII and PvuII digestions and ethidium bromide staining, gave indistinguishable patterns for the strains isolated from the neonate, his mother, and patient 2. Strains from patient 3 and six unrelated strains studied for comparison showed different patterns. In our system, ribotyping was less discriminative than total DNA RFLP analysis. DNA RFLP analysis therefore provides a valuable molecular tool for studying S. pyogenes epidemiology.

Adult↗
PubMed1992

Analysis of DNA restriction fragment length polymorphism extends the evidence for breast milk transmission in Streptococcus agalactiae late-onset neonatal infection.

Analysis of restriction fragment length polymorphism (RFLP) of total DNA and of ribosomal DNA (ribotyping) was used to document four cases of Streptococcus agalactiae mother-to-infant transmission potentially associated with ingestion of infected mother's milk. Twenty strains were analyzed. Ten strains were mother-baby pairs, five from the milk of five mothers, four from their neonates with late-onset infection, and one from a colonized neonate. All mothers had early postpartum mastitis. Ten unrelated strains were studied for comparison. In each case, the two strains of each mother-baby pair produced identical RFLP patterns of total DNA. The 10 unrelated strains generated 10 different patterns, one of which, though, was observed in one of the mother-baby pairs. Ribotyping was less discriminative than total DNA RFLP analysis (6 different patterns vs. 13). These data extend the evidence for breast milk transmission in S. agalactiae late-onset neonatal infection.

Breast Feeding↗
PubMed1992

DNA restriction fragment length polymorphism differentiates recurrence from relapse in treatment failures of Streptococcus pyogenes pharyngitis.

In the evaluation of treatment failure in Streptococcus pyogenes pharyngitis it is necessary to distinguish between persistence of the original streptococcus and acquisition of a new strain. We used the analysis of restriction fragment length polymorphism (RFLP) of total DNA and of ribosomal DNA (rDNA) regions (ribotypes) as epidemiological tools to compare 43 pre- and post-treatment S. pyogenes strains obtained from 20 patients. In 16 cases pre- and post-treatment strains gave indistinguishable RFLP patterns of total DNA, strongly suggesting relapse with the same strain. However, in four cases different patterns were obtained for the pre- and post-treatment isolates, indicating recurrence due to the acquisition of a new strain. Ribotyping did not improve discrimination among strains. Thus, analysis of DNA RFLP is a promising method for distinguishing recurrence from relapse in failures of pharyngitis treatment.

DNA, Bacterial↗
PubMed1992

Molecular epidemiology unravels the complexity of neonatal Escherichia coli acquisition in twins.

Combined analysis of restriction fragment length polymorphism of regions of genes coding for rRNA (ribotyping) and esterase electrophoretic typing was used to document neonatal acquisition of Escherichia coli in twins. Our study shows vertical mother-to-infant transmission of one strain of E. coli to one twin and the development of neonatal septicemia with a distinct nonvirulent carboxylesterase type B1 E. coli strain for the other twin.

Adult↗
PubMed1992

Ribotyping provides efficient differentiation of nosocomial Serratia marcescens isolates in a pediatric hospital.

Ribotyping with a nonradioactive probing system was used for the epidemiological evaluation of 15 Serratia marcescens nosocomial strains isolated from the stools of 12 children with no apparent illness in five different hospital wards over a 20-day period. Our results indicate that the occurrence of S. marcescens colonization was the result of the spread of a single epidemiological strain in the hematology ward, the oncology ward, and the gastroenterology ward and in two neonates in the neonatology ward, suggesting cross-contamination between the patients in these four wards. This isolate was genotypically unrelated to the bacterial strain found in the three other patients in the neonatology ward. Interestingly, one patient in the neonatology ward harbored these two genotypically different strains. Finally, the patient in the intensive care unit was colonized with a different strain. We find ribotyping to be a more reliable technique than biochemical typing. The results of ribotyping are more easily interpreted than are those of total DNA analysis, with an equivalent degree of discrimination.

Bacterial Typing Techniques↗
PubMed1992

[Epidemiology of Chlamydia trachomatis using analysis of gene encoding of the major outer membrane protein].

One hundred and eight clinical strains and 24 reference strains of C. trachomatis were typed using differential restriction mapping of omp1, the gene which encodes the major outer membrane protein. The gene was obtained by polymerase chain reaction (PCR). This molecular typing method correlated well with serological typing. Eighty-four per cent of clinical strains were typed using the enzyme AluI alone. Heterogeneity was looked for among the most common serovars (E, F, and D; 62%, 17%, and 9%, respectively). Analysis of the PCR-amplified fourth variable domain of omp1 using denaturing gradient gel electrophoresis followed by direct sequencing of the variants disclosed substantial heterogeneity within the D serovar. Conversely, serovars E and F were homogeneous, with however a single variant strain of serovar E.

Bacterial Outer Membrane Proteins↗
PubMed1992

[HbD Iran-beta-thalassemia association in a Tunisian family].

A nine-year-old boy from Béjà (North-Western Tunisia) was found to have both HbD Iran and beta-thalassemia. This patient presented with anemia and slight enlargement of the spleen and had a history of acute episodes of hemolysis. Structural studies on this hemoglobin variant used several miniaturized techniques, mainly carboxy-methyl-cellulose chromatography, reverse-phase high performance liquid chromatography and manual peptide sequencing using Chang's technique. The glutamic acid in position 22 on the beta chain was found to be replaced by a glutamine, establishing the diagnosis of HbD Iran. Concomitant presence of a thalassemia trait was suggested by the finding in the index patient of microcytosis, hypochromia and increased HbA2. The family study confirmed this patient's combined heterozygous anomalies, showing the D trait in the father and the beta thalassemia trait in the mother. The same combination was found in the index patient's sister who was, however, free of clinical symptoms. The explanation of this difference in clinical expression was provided by the ADN study which disclosed deletion of an alpha gene in the girl. The resulting alpha chain deficiency counterbalanced the beta chain deficiency.

Amino Acid Sequence↗