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C Sayada

Publications and source records attributed to C Sayada.

29 records · Page 2Linked to original sources
PubMed1994

[Alpha-thalassemia].

alpha-Thalassaemias are probably the most common genetic disorder worldwide. alpha-Thalassaemias are haemolytic anaemias resulting from inherited deficient synthesis of alpha-globin chains. In this paper, the classification and nomenclature of alpha-thalassaemias are developed. Procedures to ensure the laboratory diagnosis are explained. The heterozygous carrier states for these disorders are, in most cases, not associated with any easily discernible change in the haemoglobin pattern, except, sometimes, a reduced MCV in the blood picture. Heterozygotes for alpha-thalassaemia deletions are now detectable by the accurate PCR method. Because of the high prevalence of these disorders in large segments of the world population, alpha-thalassemia and haemoglobinopathies often occur in the same individual. The laboratory features of these interactions and, particularly, the role of alpha-thalassaemia as a potential modulator of sickling haemoglobinopathies are discussed.

Humans↗
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↗
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

[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↗
PubMed1991

Rapid genotyping of the Chlamydia trachomatis major outer membrane protein by the polymerase chain reaction.

Twenty one Chlamydia trachomatis reference strains and 40 clinical isolates belonging to the lymphogranuloma venerum (LGV) and trachoma biovars were genotyped by differential restriction mapping of the major-outer-membrane-protein gene (MOMP) obtained by the polymerase-chain reaction (PCR). AluI digestion of the PCR product distinguishes eight MOMP-genotypes corresponding to 8 serovars. Six additional enzymes (NlaIII, CfoI, EcoRI, HinfI, DdeI and FokI) further permit the discrimination of 10 MOMP-genotypes corresponding to the 10 remaining serovars of the species. AluI alone allows direct typing of 78% of the clinical isolates. AluI digestion patterns of mouse C. trachomatis biovar, a C. pneumoniae and two C. psittaci strains, studied for comparison, were clearly distinguishable from one another and from the C. trachomatis LGV and trachoma strains. These results indicate that MOMP genotyping by PCR is a valuable molecular tool for studying C. trachomatis epidemiology.

Bacterial Outer Membrane Proteins↗
PubMed1991

Restriction pattern of the major outer-membrane protein gene provides evidence for a homogeneous invasive group among ruminant isolates of Chlamydia psittaci.

Thirty-six ruminant isolates of Chlamydia psittaci, previously classified as invasive or non-invasive in a mouse model of virulence, were compared by analysing AluI restriction patterns of the major outer-membrane protein (MOMP) gene after DNA amplification by the polymerase chain reaction. The 24 invasive isolates, although from various origins, all belonged to serotype 1 and represented a strictly homogeneous group sharing a specific MOMP-gene restriction pattern that was not observed in the non-invasive strains. On the other hand, the 12 non-invasive strains, although all belonging to serotype 2, constituted a heterogeneous group with eight distinct MOMP-gene restriction patterns. However, all eight patterns shared a 180 bp fragment or the corresponding restricted fragments of 110 and 70 bp. MOMP-gene restriction patterns also clearly distinguished the ruminant strains from an avian C. psittaci isolate, a C. pneumoniae isolate and two C. trachomatis isolates which were studied for comparison. The homogeneous character of the invasive C. psittaci strains argues strongly for their genetic relatedness. Our results illustrate the usefulness of the MOMP-gene restriction mapping in typing chlamydiae.

Animals↗
PubMedDate not supplied

Analysis of the 5' flanking sequence of the G gamma globin gene by denaturing gradient gel electrophoresis confirms the heterogeneity of the Bantu beta S haplotype.

The GC-->TT polymorphism recently described at positions -1106 and -1105 in the 5' flanking region of the G gamma globin gene for the Bantu beta S haplotype was analysed by denaturing gradient gel electrophoresis. We studied 108 beta S chromosome and 122 beta A chromosomes. The TT sequence was found as follows: in all of 80 chromosomes bearing the Bantu beta S haplotype with the 6-bp deletion -400 nt from the G gamma gene in 3 out of 5 Bantu beta S chromosomes without the deletion, in 1 out of 122 beta A chromosomes from different ethnic origins but in none of 23 beta S chromosomes bearing the Senegal, Benin or Cameroon haplotypes. These results confirm the heterogeneity of the Bantu beta S haplotype and allow a tentative evolutionary sequence for the different alleles at this locus to be presented.

Anemia, Sickle Cell↗
PubMedDate not supplied

HIV-1 replication in the plasma and cerebrospinal fluid.

The HIV-1 RNA in plasma and CSF samples from 40 HIV-1 infected patients was measured by a polymerase chain reaction (PCR) technique. The possible implication of cytokines in HIV-1 replication was investigated by measuring the concentrations of tumor necrosis factor alpha (TNF-alpha), macrophage colony stimulation factor (M-CSF) and interleukin-6 (IL-6) in these fluids. HIV-1 RNA was quantified in all plasma samples and in 87.5% of the CSF samples. CSF HIV-1 RNA titers did not correlate with the stage of disease or the CD4+ T cell counts, unlike the plasma HIV-1 RNA titers. These results were confirmed when patients with a blood brain barrier damage, as assessed by the CSF/ plasma albumin ratio, were excluded from the analysis. TNF-alpha levels were statistically correlated with the HIV-1 RNA in plasma and CSF. These data demonstrate that HIV-1 replication in the CSF at each clinical stage can be accurately measured with PCR and, although the titers of HIV-1 RNA copies in the CSF are correlated with those in the plasma, the magnitude of HIV-1 replication in CSF is not directly linked to the stage of disease, or to the CD4+ T cell count. The significance of early high levels of HIV-1 RNA in CSF is now being studied prospectively.

Adult↗