Samir Boubaker

A novel missense mutation in the gene encoding SLURP‐1 in patients with Mal de Meleda from northern Tunisia

Background  Mal de Meleda (MDM) is a rare autosomal recessive skin disorder which belongs to the clinically and genetically heterogeneous group of palmoplantar keratodermas (PPK). Clinically, MDM is characterized by erythema and hyperkeratosis of the palms and soles with sharp demarcation that appears soon after birth and progressively extends to the dorsal surface of the hands and feet.

Histopathological changes induced by Hemiscorpius lepturus scorpion venom in mice

Envenomation by Hemiscorpius lepturus (H. lepturus) is associated with local necrosis, followed by systemic manifestations. In this work the LD₅₀ of H. lepturus venom were determined by subcutaneous (SC) injection in white Balb/c mice (5 mg/kg). Histopathological alterations in organs such as kidney, heart, liver, lungs, stomach and intestine were determined in 3, 6, 12 and 24 h following experimental (SC) envenoming injection of one LD ₅₀ of the venom in Balb/c mice. Histological studies showed degenerative changes in the kidney with disorganized glomeruli and necrotic tubular in 3 h and reached to its climax in 6 h. Myocardium showed massive myocytolysis with interstitial necrosis in 3 h and reached to its peak after 6 h past envenoming. Bowels showed edema of lamina propria and slight villous necrosis. The enzymatic activities of creatine kinase (CK) and lactate dehydrogenase (LDH) were significantly increased in the serum in 9 h. No necrotic lesion observed in lungs and liver. The results indicate that the venom of H. lepturus is a highly cytotoxic, and induces massive tissue damages in specific organs, starting from the heart and kidney as the first target in 3 h and ends to the bowels in 6 h post envenomation.

Involvement of granzyme B and granulysin in the cytotoxic response in lichen planus

Background:  Lichen planus is an inflammatory dermatosis involving either skin and/or mucosal epithelial surfaces. A cell‐mediated cytotoxicity response is the main suspected mechanism of this dermatosis. Granzyme B and granulysin are components of the cytoplasmic granules of cytotoxic T lymphocytes and natural killers. They are involved in cell‐mediated apoptosis. This work studies the possible implication of granzyme B and granulysin in the cell‐mediated cytotoxicity response in lichen planus.

Clinical and Mutational Heterogeneity of Darier Disease in Tunisian Families

OBJECTIVE To study the mutation spectrum and phenotype-genotype correlation of Darier disease (DD) in Tunisian patients. DESIGN Case series. SETTING Referral center: Department of Dermatology (La Rabta Hospital), Tunis, Tunisia. PATIENTS Eight large Tunisian families with DD, with a total of 23 patients and 9 unaffected family members. MAIN OUTCOME MEASURE Patients were investigated at the clinical, histological, and genetic levels. Families were genotyped with 5 microsatellite markers spanning the ATP2A2 gene. Mutation screening was performed by direct sequencing of the coding region and exon/intron boundaries of the ATP2A2 gene. RESULTS Typical clinical features of DD were constantly present. Phenotypic variation within and between the studied families was observed. Different neuropsychiatric disorders were seen in 5 families, and various cutaneous and extracutaneous original clinical associations were observed. The haplotype analysis led to the identification of different haplotypes cosegregating with the disease in the studied families. Mutation screening of the ATP2A2 gene revealed 3 recurrent mutations (119-120delAG, R677X, and D702N) and 4 novel variations: 2 missense mutations (G217A and L900R), one microinsertion (2772-2779 ins C), and one microdeletion (1747-1749 del 2T). CONCLUSIONS Our findings provide evidence for clinical and mutational heterogeneity of Tunisian families with DD. No obvious phenotype-genotype correlation was established. To our knowledge, this is the first molecular investigation of DD in the North African population.

Prognostic Value of Tumor-associated Macrophages Count in Human Non-muscle-invasive Bladder Cancer Treated by BCG Immunotherapy

Purpose: Tumor-associated macrophages can regulate the growth of various cancers positively or negatively. Intravesical bacillus Calmette-Guerin instillation is now the gold standard treatment for bladder carcinoma in situ. The authors investigated the correlation between tumor-associated macrophages infiltrating bladder carcinoma in situ and the response to intravesical bacillus Calmette-Guerin therapy. Materials and methods: The authors examined paraffin-embedded tissues from 41 patients with bladder carcinoma in situ who received intravesical bacillus Calmette-Guerin therapy. Tumor-associated macrophages were immunohistochemically stained by anti-CD68 monoclonal antibody. Results: The median number of tumor-associated macrophages infiltrating among cancer cells and the number in the lamina propria were 4 and 24, respectively. Recurrent carcinoma in situ was found in 4.8% of cases with a lower cancer cell tumor-associated macrophage count but in 47.6% of those with a higher cancer cell tumor-associated macrophage count (less than 4 vs. 4 or greater). Recurrence was found in 31.8% of patients with a lower lamina propria tumor-associated macrophage count but in 21.1% of those with a higher lamina propria tumor-associated macrophage count (less than 25 vs. 25 or greater). The median ratio of tumor-associated macrophages among cancer cells vs. in the lamina propria was 0.2. Recurrence-free survival was significantly better in patients with a lower cancer cell tumor-associated macrophage count (p = .0002). Those with a lower cancer cell-to-lamina propria tumor-associated macrophage ratio had a higher recurrence-free rate (p < .0001). Multivariate analysis revealed that the cancer cell tumor-associated macrophage count and the cancer cell-to-lamina propria tumor-associated macrophage ratio can be prognostic factors for bladder carcinoma in situ. Conclusions: The count of tumor-associated macrophages infiltrating the cancer area is useful for predicting the response of bladder carcinoma in situ to intravesical bacillus Calmette-Guerin instillation before treatment initiation. Although on univariate analysis TAMs are associated with other poor prognosticators, on multivariate analysis, TAMs appear only to be associated with MI and VI. TAMs may play a significant role in the biology of tumor progression of endometrial adenocarcinoma, but do not appear to be independent prognostic indicators of patient’s survival.

Prognostic Impact of Angiogenesis in Nonmuscle Invasive Bladder Cancer as Defined by Microvessel Density after Immunohistochemical Staining for CD34

Bladder cancer is the second most common malignancy of the urogenital region. The majority of bladder cancer deaths occur as a consequence of metastatic disease. Microvessel density (MVD), a surrogate marker for angiogenesis, has been shown to be predictive of progression and poor prognosis. The aim of this study was to evaluate the predictive value and prognostic significance of angiogenesis in human non muscle invasive bladder cancer (NMIBC) treated by BCG immunotherapy. The frozen sections of 28 non muscle invasive bladder cancer specimens were stained with CD34 antibody to label the vascular endothelium using the standard streptavidin-biotin immunoperoxidase method. Angiogenic activity was measured using microvessel count determined by the expression of vascular markers CD34.The prognostic significance of tumor stage, grade, loci number, tumor size, age and CD34 expression in determining the risk for recurrence was studied with both univariate and multivariate methods of analysis. According to univariate analysis of the prognostic significance for tumor stage, grade, tumor size, loci number, age and CD34 expression, in patients with NMIBC, the pT1 stage and high grade seem to be associated in a statistically significant manner with higher risk for recurrence (P=0.004, P=0.004, respectively). In the other hand, multivariate Cox regression’s analysis showed that microvessel density and multiplicity were independent predictor of recurrence after BCG immunotherapy (p=0.016, p=0.032, respectively). This study provides strong evidence that CD34 MVD is associated with recurrence after BCG immunotherapy. Independent studies, however, will be required on larger cohort to validate these findings.

Immunohistological study of involucrin expression in Darier's disease skin

Background:  Darier’s disease (DD) is an autosomal dominant skin disorder characterized by acantholysis and abnormal keratinization. The gene responsible for DD, ATP2A2 encodes for the sarco/endoplasmic reticulum (ER) Ca2+‐ATPase isoform 2 protein. Involucrin, considered as a marker of terminal epidermal differentiation, could be altered in some keratinization disorders including DD.

Genetic homogeneity of mutational spectrum of group-A xeroderma pigmentosum in Tunisian patients

Background  Xeroderma Pigmentosum (XP) is a rare autosomal recessive disorder characterized by cutaneous and ocular alterations. Eight genes, Xeroderma Pigmentosum group A (XPA) to Xeroderma Pigmentosum group G (XPG) and Xeroderma Pigmentosum group V (XPV), are known to be responsible for the disease and products of these genes are involved in the repair of deoxyribonucleic acid (DNA) lesions generated by UV radiation. Several XP patients suffer from neurological defects, found in the XPA (the most common form), D and G groups. The aim of this study was to investigate the mutational spectrum of XPA in Tunisia, in order to propose a simple tool for molecular diagnosis.

Keratinocyte sensitization to tumour necrosis factor-induced nuclear factor kappa B activation by the E2 regulatory protein of human papillomaviruses.

Human papillomavirus (HPV) life cycle requires extensive manipulation of cell signalling to provide conditions adequate for viral replication within the stratified epithelia. In this regard, we show that the E2 regulatory protein of α, β and μ-HPV genotypes enhances tumour necrosis factor (TNF)-induced activation of nuclear factor kappa B (NF-κB). This activation is mediated by the N-terminal domain of E2, but does not rely on its transcriptional properties. It is independent of the NF-κB regulator Tax1BP1, which nevertheless interacts with all the E2 proteins. E2 specifically activates NF-κB pathways induced by TNF, while interleukin-1-induced pathways are not affected. E2 stimulates the activating K63-linked ubiquitination of TRAF5, and interacts with both TRAF5 and TRAF6. Our data suggest that E2 potentiates TNF-induced NF-κB signalling mediated by TRAF5 activation through direct binding. Since NF-κB controls epithelial differentiation, this activity may be involved in the commitment of infected keratinocytes to proliferation arrest and differentiation, both required for the implementation of the productive viral cycle.

Protective effect of Artemisia campestris extract against aspirin-induced gastric lesions and oxidative stress in rat

The present study aims at evaluating the antiulcer and antioxidant effect of Artemisia campestris aqueous extract (ACAE) as well as the mechanism of action involved in such gastroprotection. The use of LC/MS allowed the identification of 11 phenolic compounds and the colorimetric analysis demonstrated that the ACAE exhibited an important in vitro antioxidant activity. We first showed that in vivo ACAE protected against macroscopic and histological changes induced by aspirin in stomach mucosa. Aspirin administration was accompanied by an oxidative stress status assessed by an increase in malondialdehyde (MDA) level, a decrease in the content of sulfhydryl –(SH) groups and a depletion of antioxidant enzyme activities such as superoxide dismutase (SOD), catalase (CAT) and glutathione peroxidase (GPx). Pre-treatment with ACAE protected against aspirin-induced gastric oxidative stress. More importantly, aspirin administration increased plasma and tissue hydrogen peroxide (H2O2), free iron and calcium levels, while the ACAE pre-treatment reversed all the effects of aspirin-induced intracellular mediators. In conclusion, we suggest that Artemisia campestris aqueous extract has potent antiulcer and antioxidant properties. This gastroprotection offered by ACAE might be related partly to the safety of sulfhydryl group as well as its opposite effect on some intracellular mediators such as hydrogen peroxide, free iron and calcium.