Biomedical subjects

Mohamed Bejaoui

Publications and source records attributed to Mohamed Bejaoui.

11 recordsLinked to original sources

PubMed2006

X-linked susceptibility to mycobacteria is caused by mutations in NEMO impairing CD40-dependent IL-12 production.

Germline mutations in five autosomal genes involved in interleukin (IL)-12-dependent, interferon (IFN)-gamma-mediated immunity cause Mendelian susceptibility to mycobacterial diseases (MSMD). The molecular basis of X-linked recessive (XR)-MSMD remains unknown. We report here mutations in the leucine zipper (LZ) domain of the NF-kappaB essential modulator (NEMO) gene in three unrelated kindreds with XR-MSMD. The mutant proteins were produced in normal amounts in blood and fibroblastic cells. However, the patients' monocytes presented an intrinsic defect in T cell-dependent IL-12 production, resulting in defective IFN-gamma secretion by T cells. IL-12 production was also impaired as the result of a specific defect in NEMO- and NF-kappaB/c-Rel-mediated CD40 signaling after the stimulation of monocytes and dendritic cells by CD40L-expressing T cells and fibroblasts, respectively. However, the CD40-dependent up-regulation of costimulatory molecules of dendritic cells and the proliferation and immunoglobulin class switch of B cells were normal. Moreover, the patients' blood and fibroblastic cells responded to other NF-kappaB activators, such as tumor necrosis factor-alpha, IL-1beta, and lipopolysaccharide. These two mutations in the NEMO LZ domain provide the first genetic etiology of XR-MSMD. They also demonstrate the importance of the T cell- and CD40L-triggered, CD40-, and NEMO/NF-kappaB/c-Rel-mediated induction of IL-12 by monocyte-derived cells for protective immunity to mycobacteria in humans.

Adolescent↗

PubMed2006

Kaposi's sarcoma in a child with Wiskott-Aldrich syndrome.

INTRODUCTION: Kaposi's sarcoma (KS) is rare in childhood. It may be favored by acquired immune deficiencies, but the predisposing factors to KS in other children are unclear. DISCUSSION: KS has been reported in only two children and one adult with primary immunodeficiency. We report here a Tunisian child with a Wiskott-Aldrich syndrome who developed KS at the age of 14 months. CONCLUSION: This observation expands the spectrum of primary immunodeficiencies associated with KS in childhood.

Combined Modality Therapy↗

PubMed2006

[Deficient expression of leukocyte adhesion proteins. A new Tunisian case].

Leukocyte adhesion deficiency (LAD) is a rare primary immunodeficiency inherited as an autosomal recessive genetic disorder. LAD was suspected in a four days old girl. She was born from healthy first cousins. A family history of a boy who died from omphalitis and sepsis was reported. Our patient had the severe form, she had delayed umbilical cord separation and suffered recurrent infections. She had a deletion of the G at position 1497. The patient received bone marrow transplantation from her HLA-identical mother at age of 14 months. She is now 9 years old and in good health.

Bone Marrow Transplantation↗

PubMed2005

A phase 3 study of deferasirox (ICL670), a once-daily oral iron chelator, in patients with beta-thalassemia.

Deferasirox (ICL670) is a once-daily oral iron chelator developed for the treatment of chronic iron overload from blood transfusions. A comparative phase 3 trial was conducted to demonstrate the efficacy of deferasirox in regularly transfused patients with beta-thalassemia aged 2 years or older. Patients were randomized and received treatment with deferasirox (n = 296) or deferoxamine (n = 290), with dosing of each according to baseline liver iron concentration (LIC). The primary endpoint was maintenance or reduction of LIC; secondary endpoints included safety and tolerability, change in serum ferritin level, and net body iron balance. In both arms, patients with LIC values of 7 mg Fe/g dry weight (dw) or higher had significant and similar dose-dependent reductions in LIC and serum ferritin, and effects on net body iron balance. However, the primary endpoint was not met in the overall population, possibly due to the fact that proportionally lower doses of deferasirox relative to deferoxamine were administered to patients with LIC values less than 7 mg Fe/g dw. The most common adverse events included rash, gastrointestinal disturbances, and mild nonprogressive increases in serum creatinine. No agranulocytosis, arthropathy, or growth failure was associated with deferasirox administration. Deferasirox is a promising once-daily oral therapy for the treatment of transfusional iron overload.

Administration, Oral↗

PubMed2004

Contribution to the description of the beta-thalassemia spectrum in Tunisia and the origin of mutation diversity.

We determined the spectrum of beta-thalassemia (thal) mutations in 118 affected unrelated patients with different forms of beta-thal. Using a combination of reverse dot-blot analysis, denaturing gradient gel electrophoresis (DGGE), polymerase chain reaction/restriction fragment length polymorphism (PCR/RFLP) and direct nucleotide sequencing, we identified the largest spectrum of beta-thal mutations so far reported in Tunisia, and to the best of our knowledge, within the Mediterranean Basin. A total of 18 distinct alleles were detected at different frequencies, with two alleles [codon 39 (C-->T) and IVS-I-110 (G-->A)] predominating all others. Seven other alleles [frameshift at codon (FSC) 6 (-A), FSC 8 (-AA), codon 30 (G-->C), IVS-I-1 (G-->A), IVS-I-2 (T-->G), IVS-I-6 (T-->C), FSC 44 (-C)] were rare, and nine alleles [-29 (A-->G), IVS-I-2 (T-->C), IVS-I-5 (G-->C), IVS-I-5 (G-->T), IVS-I-116 (T-->G), codon 37 (G-->A), IVS-II-1 (G-->A), IVS-II-745 (G-->C) and IVS-II-849 (A-->C)], albeit described elsewhere, are reported here in Tunisia for the first time. The codon 39 and IVS-I-110 mutations were the two predominant alleles occurring at frequencies of 43.8% and 10.8%, respectively. They are presumably the earliest mutations introduced into this country. The codon 39 allele could have been introduced in Tunisia during the Roman occupation. Similarly, the IVS-I-110 mutation might have been introduced by the Turkish and Phoenician influence. Both gene flow and private mutations may account for the diversity of alleles observed in Tunisia. These data provide the background for implementing prevention programs based on genetic counseling and prenatal diagnosis.

Alleles↗

PubMed2004

Anti-thrombomodulin antibodies and venous thrombosis.

Thrombomodulin (TM) is a cell surface endothelial glycoprotein having anticoagulant properties. It inhibits thrombin, and activates protein C, leading to the inhibition of activated factors V and VIII. TM autoantibodies could theoretically predispose to thrombosis. We have tested 83 unselected patients with deep venous thrombosis, 36 males and 47 females aged from 1 to 70 years [mean +/- standard deviation (SD), 34.2 +/- 14.5 years] for the presence of IgG anti-TM in their plasmas. Tests were performed by enzyme-linked immunosorbent assay (ELISA) using recombinant human TM kindly provided by PAION GmbH (Aachen, Germany). Results are expressed as the optical density (OD) differences between coated and un-coated wells. Plasmas from 83 normal volunteer donors were used to define the cut-off value as the mean of absorbance of the control group + 3 SDs. The median OD of normal controls group was 0.024 (mean, 0.034; SD, 0.066; range, -0.048 to 0.309). The median OD obtained with plasmas from patients was 0.048 (mean, 0.114; SD, 0.215; range, -0.039 to 1.312) and was significantly higher than that of the control group (P < 0.0001). Choosing a cut-off value of 0.232 (mean OD of the control group + 3 SDs), 11 patients are considered as positive for IgG autoantibodies to TM and three normal controls are weakly positive. Selected plasma with IgG anti-TM and purified IgG were further tested by dot blot using recombinant purified TM and were found positive. Purified IgG of positive plasmas inhibits protein C activation by TM and thrombin, suggesting that anti-TM antibodies have a procoagulant effect. Interestingly, in our study, anti-TM antibodies are found in three of six patients with Budd-Chiari syndrome and four of eight patients with cerebral venous thrombosis. In conclusion, thrombomodulin autoantibodies could be a new interesting marker of thrombophilia easily detected by ELISA.

Adolescent↗

PubMed2003

[The hyper-IgM syndrome: 13 observations].

INTRODUCTION: The hyper-IgM syndrome (HIGM) is a rare hereditary immune deficiency, characterised by a low or nil level of IgG and IgA and a normal or increased level of IgM, predominately affecting boys. Its clinical manifestations are dominated by recurrent infection, notably of the digestive tube, the ears nose and throat and the lungs. METHODS: We conducted a retrospective study of the medical files of 13 patients with 10 boys and 3 girls from 12 different families. In all the patients, the diagnosis was established on measuring the serum immunoglobulines IgG, IgA and IgM using Mancini's technique. RESULTS: The mean age at the onset of the disease was of 20 months (6 - 42 months). The clinical manifestations were dominated by recurrent and persisting infections, notably digestive (10 cases), respiratory (9 cases), cutaneous (5 cases) and glandular (5 cases). No pulmonary Pneumocystis carinii infection or sclerosing Cryptosporidium cholangitis was observed. Two boys exhibited neurological manifestations, unrelated to an infection. The IgG deficiency was constant and IgA deficieny encountered in 12 patients. Ten patients exhibited a high level of IgM (4.6 - 29,9 g/l) whereas this was normal in the 3 others. The expression of the CD(40) ligand was absent in the 6 boys in whom it was assessed and normal in the only girl studied. Eleven patients exhibited concomitant cellular immune deficiency. Three patients presented moderate neutropenia. Nine patients received replacement therapy with IV immunoglobulines with a residual level of IgG at 8,27 g/l (4 - 14,45 g/l) associated with the regression in the manifestations of infection. One patient died from a Burkitt lymphoma before any treatment was initiated. CONCLUSION: The primary hyper-IgM syndrome in Tunisia is characterised by a relative frequency of autosomal recessive forms (3 girls), the absence of Pneumocystis carinii pulmonary infections and sclerosing cholangitis and the occurrence of neurological manifestations (2 cases).

Adolescent↗

PubMed2003

Oxidant, antioxidant status and metabolic data in patients with beta-thalassemia.

BACKGROUND: In beta-thalassemia major impaired biosynthesis of beta globin leads to accumulation of unpaired alpha globin chain. An iron overload, usually observed, generates oxygen-free radicals and peroxidative tissue injury. AIM: To investigate hematological parameters, oxidative stress and the antioxidant capacity in beta-thalassemia patients compared to control subjects in order to determine their impact in several organs functions. METHODS: This study was conducted on 56 beta-thalassemia major patients compared to 51 healthy subjects. We determined metabolic parameters (glycaemia, lipid parameters, electrolytes, iron indices, hepatic, renal and heart functions tests), plasmatic thiobarbituric acid reactive substances (TBARS), plasmatic peroxyl radical trapping potential (TRAP), plasmatic superoxide dismutase (SOD), erythrocyte gluthathione peroxidase (GPX), plasmatic vitamin E, vitamin A and trace elements. RESULTS: Except triglycerides, lipid fractions were significantly decreased in beta-thalassemia compared to controls. Serum ferritin, iron, TBARS concentrations, SOD and GPX activities were significantly increased. But TRAP, vitamin E and zinc concentrations were significantly decreased. CONCLUSION: Our findings confirm the peroxidative status generated by iron overload in beta-thalassemia major patients and highlight the rapid formation of marked amounts of TBARS and the increase of SOD and GPX activity. Our study suggested that in beta-thalassemia the first organ impaired is the liver.

Antioxidants↗

PubMed2003

Community-acquired poliovirus infection in children with primary immunodeficiencies in Tunisia.

The global polio eradication program recommends the use of massive vaccination campaigns with live vaccine through National Immunization Days (NIDs) to displace the wild virus from the community. Immunodeficient patients may be indirectly infected and become chronic excretors and potential reservoirs of polioviruses, a concern for the posteradication era. This prospective study aimed to assess the risk of community-acquired infection of immunodeficient patients following NIDs, the dynamics of viral excretion and the genetic variation of excreted viruses. Sixteen children with various primary immunodeficiencies, who did not receive the vaccine during the campaign, were investigated. Stool samples were collected weekly, shortly after the NIDs, during at least 3 months, and were processed for viral isolation. Isolates were characterized by three intratypic differentiation methods and partial sequencing of the VP1/2A region. Polioviruses were detected in 4 out of 16 patients (serotype 1 in 3 patients and serotype 3 in 1 patient). Sequencing revealed more than 99% homology with homotypic Sabin strains, suggesting recent infection. Duration of viral excretion ranged from 1 to 7 weeks. Nine out of eleven isolates from the three poliovirus serotype 1-infected patients disclosed a non-Sabin-like phenotype by enzyme-linked immunosorbent assay and had recurrent mutations within or close to the neutralizing antigenic sites. In summary, the risk of secondary infection in immunodeficient patients is within the range previously reported for the general population. Although none of the four infected patients developed prolonged viral excretion, particular viral variants were selected and may be of epidemiological significance.

Child↗

PubMed2003

[A congenital deficiency of the C3 fraction of complement. A familial study].

The innate deficit of the third constituent of the complement is extremely rare, it appears clinically as a deficit of the humorale immunity. We report a case of C3 deficit in a 6 year old Tunisian child, who presents a psychomotor delay and recurrent infections. The investigation of the complement system profile by an immunochemical test of the children's serum shows an absence of C3 and C3d, associated to a loss of classic and alternate hemolytic pathway activities. The addition of functional C3 in the deficient serum restores the global hemolytic activity. The reconstruction of the hemolytic activity is dose dependent of C3 added quantity. The rate of C3 is lowered in the parent's with a 50% decrease of the global hemolytic activity. Immunochemical measurement of C3d confirms the absence of any C3 catabolism product in vivo. On the other hand (factor I) show a normal rate to all the family members.

Child↗

PubMed2002

[Bronchopulmonary aspergillosis: study of 17 cases].

Aspergillosis is a fungic infection depending on the local or general physiologic and immunologic state of the host. We report the result of retrospective five year study (1995-1999) about 17 cases in the laboratory of Parasitology-Mycology of Rabta hospital in Tunis. Six aspergillomas were observed, they occurred after a pulmonary tuberculosis, two cases of allergic broncho-pulmonary aspergillosis described in two asthmatic patients, nine cases of invasive pulmonary aspergillosis complicating two cancers, one leukaemia, six chronic granulomatous disease. Aspergillus fumigatus is the most frequent species (67%). The clinical and biological characteristic of those will be studied, and compared with those of the literature.

Adult↗