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Biomedical subjects

K Ayed

Publications and source records attributed to K Ayed.

At least 19 recordsLinked to original sources
PubMed1992

C4 polymorphism in multiplex families with insulin dependent diabetes in the Tunisian population: standard C4 typing methods and RFLP analysis.

The polymorphism of C4A and C4B genes was investigated in Tunisian patients with insulin dependent diabetes (IDDM) and compared to family members (sibs) and to healthy controls. Multiplex families were analysed. A significant increase in C4AQO (26.86% vs 6.90%) and C4BQO (40.29% vs 8.28%) phenotypes was noted in IDDM patients compared with controls. Using RFLP analysis, we confirmed the high frequency of C4 null alleles. We also observed that most of these alleles were genes deleted in IDDM patients (72.23% vs 20% for CA4QO and 74.07% vs 16.70% for C4BQO). A significant decrease in the C4B long (14.92% vs 67.12%) form of the gene was also demonstrated by RFLP analysis compared with controls. Two haplotypes were frequently associated with IDDM patients in whom the C4A and C4B were deleted genes.

Adolescent↗
PubMed1992

[Characterization and evolution of blood cryoglobulin in visceral leishmaniasis].

The evolution of immunological parameters in mediterranean visceral leishmaniasis reveal a type III mixed cryoglobulin with rhumatoid factor activity and antileishmania antibodies. This cryoglobulin follows the clinical signs of the disease and disappear under treatment. The authors insist on the transitory character of this cryoglobulin which is in relation with polyclonal stimulation of the immune system by parasitical infection.

Adult↗
PubMed1992

Abnormalities of T lymphocyte subsets in Behçet's disease demonstrated with anti-CD45RA and anti-CD29 monoclonal antibodies.

We assessed T cell subpopulations using 2-color flow cytometry with phycoerythrin conjugated anti-CD45RA and anti-CD29 and fluorescein conjugated anti-CD4 and anti-CD8 monoclonal antibodies, on peripheral blood lymphocytes from 19 patients with Behçet's disease (BD) and 18 healthy control subjects. The percentage of CD4+ cells was significantly lower in patients with BD (34 +/- 2%) than in control subjects (46 +/- 3%) (p less than 0.001). Among CD4+ cells, the percentage of suppressor-inducer (CD4+CD45RA+) cells was significantly lower in patients with BD (31 +/- 4%) than in control subjects (45 +/- 2%) (p less than 0.01), while the percentages of helper-inducer (CD4+CD29+) cells were similar in patients and controls. The percentage of CD8+ cells was significantly higher in patients with BD (36 +/- 2%) than in control subjects (26 +/- 2%) (p less than 0.001) involving both CD45RA+ and CD29+ subpopulations. Within CD4+ cells, the percentage of suppressor-inducer (CD4+CD45RA+) cells was significantly decreased in patients with active BD (26 +/- 3%) compared with control subjects (45 +/- 2%) (p less than 0.001), whereas in patients with inactive BD the difference was statistically insignificant. Our results suggest that the defective suppressive function in patients with active BD may be related to the decreased suppressor-inducer subpopulation (CD4+CD45RA+).

Adult↗
PubMed1992

[Pseudo-tumoral osteomyelitis. Immunologic study and etiopathogenic approach. Apropos of 2 cases].

Two cases of pseudo-tumoral osteomyelitis are reported. The first concerns a 12 year-old boy who presented with pain of the left knee during 8 months and, later on, with swelling of the upper extremity of the left leg, without fever or local inflammatory signs. The radiological aspect of condensation with a filling defect and "chimney" crossing the cartilage led to osteotomy. Local bacteriological samplings were normal. The second case concerns a 11 year-old boy who, after having complained from pain of the right wrist during 2 weeks, presented with swelling and on X-ray films a picture of metaphyso-epiphyseal lysis and an aspect of sequestrum in its center. There was no biological sign of inflammation. Evolution was favorable after antibiotic treatment and immobilization. In both cases, an immunological study showed an activation syndrome of the immune system with increased serum IL-1, IL-2 receptors and class II antigen receptors on the surface of T cells, suggesting a previous immunization of both children towards staphylococcus and, thereby, the subacute nature of evolution.

Child↗
PubMed1979

Experimental immune glomerulonephritis induced in the rabbit with streptococcal vaccine.

Heavy C3 glomerular deposits were observed in rabbits injected intravenously with C5 streptococcal vaccine. Immunoglobulin deposits appeared later in a few rabbits. Although some data favour the presence of circulating immune complexes during the course of this glomerulonephritis, no evidence for their initiating role could be demonstrated. Streptococcal components are known to activate the alternative pathway of complement. It is suggested that complexes made of streptococcal components and activated C3 might deposit in glomerular tufts.

Agglutinins↗
PubMed1977

Complement receptors in human renal glomeruli. Further evidence by immunofluorescence.

A new method is described for demonstrating the presence of glomerular receptors for the third component of complement in human kidney. Frozen sections are incubated together with normal human serum and inulin. Activated C3 is detected by a fluoresceinated anti-C3 antiserum. Glomeruli are labelled by C3-coated inulin particles while there is no labelling in tubules and interstitium. This method is easy and rapid and it allows the exact localization of C3 glomerular receptors.

Animals↗
PubMed1976

[Comparative study of technics of screening of carriers of HBs antigen].

The purpose of this study was to compare the results of 3 reverse passive haemagglutination techniques currently used by blood centers for the HBS antigen screening in donors' blood. A comparison was also made with 3 other techniques: Radio-immuno-assay (RIA), Counter-electrophoresis (CEP), Complement fixation (CF). The sera from 2.028 blood donors were screened by all those techniques, as well as 105 known sera, used as references (87 HBS antigen positive sera with different titers, 18 HBS antigen negative sera) and coming from 4 origins: NIH-Bethesda, Centre National de Transfusion Sanguine, Paris; Hôpital de la Pitié-Salpêtrière, Paris; Hôpital Broussais, Paris. The reverse passive haemagglutination techniques were shown to be slightly less sensitive than RIA and definitely more sensitive than CEP and CF, since 18 sera were HBS antigen positive with RIA (0.88%), 10 or 12 with haemagglutination (0.40-0.59%), 8 with CF (0.39%) and 7 with CEP (0.34%). The frequency of false positive results changed with the haemagglutination technique used (0.84% for WH.HBS, to 2.3% for Hepanosticon) and involved confirmatory tests (absorption and/or neutralisation). In sum, the sensitivity, specificity and practicability of the 3 haemagglutination techniques were shown to be nearly identical, with a slight but sure advantage for the WH.HBS in our experiment. Thus reverse passive haemagglutination techniques seem, at the present time, to be the best ones for HBS antigen screening when RIA cannot be applied.

Carrier State↗
PubMedDate not supplied

Association of type 1 diabetes mellitus with the HLA-DQA1*0301 allele in a Tunisian population.

HLA class II antigens are transmembrane glycosylated heterodimers composed of an alpha and a beta chain. Several of these chains are highly polymorphic. The structural bases of the polymorphism are nucleotide acid substitutions which are situated in the first domain (exon II) of alpha and beta genes. Specific sequences of these domains can be obtained by amplification of genomic DNA using the polymerase chain reaction. Polymorphic sites are recognized by restriction endonuclease treatment and separation of the DNA fragments by polyacrylamide gel electrophoresis. The resulting fragments of different lengths are used to identify different alleles. We used the above technique for typing the HLA-DQA1 alleles in 41 Tunisian diabetic patients. The frequency of DQA1*0301 was greatly increased compared with the control group. This was in agreement with previously published data in Caucasian and Japanese insulin-dependent diabetes mellitus (IDDM) patients, while the significant increase in the frequency of the DQA1*0501 allele was comparable with that of Caucasian IDDM patients but contrasted with a decrease in this allele in Japanese IDDM patients. Our results provide confirmation of the contribution of the DQA1*0301 allele to disease susceptibility in a Tunisian population.

Alleles↗
PubMedDate not supplied

Suppressive T cell function of Epstein-Barr virus induced B cell activation in active Behçet's disease.

B and T cell function were studied in 10 patients with active Behçet's disease (BD) and in 10 normal subjects. Peripheral B lymphocytes infected with Epstein-Barr virus (EBV) were cultured for 20 days in the presence or absence of autologous T cells. Immunoglobulin M and G secretions into the supernatants were assessed with an enzyme-linked immunosorbent assay. The extent of suppression of EBV-induced B cell activation by autologous T cells was significantly decreased in active BD patients as compared to normal subjects at a T:B ratio of 1:1, whereas the suppression ratio was in the normal range at a T:B ratio of 4:1. The IgM and IgG secretions in purified B cell cultures were significantly higher in active BD patients as compared to control subjects. Thus, an increased B cell function associated with a defective EBV-specific T cell suppressive function could explain at least in part the immunological disorders in BD patients.

Adult↗