First growth reference curves for Tunisian children and adolescents.

A growth chart is a powerful graphical tool displaying children's growth patterns. The aim of this study was to develop growth reference curves appropriate for Tunisian children. The collection of data from this cross-sectional study was conducted on 4358 healthy subjects (2182 girls and 2176 boys) in three pediatric centers and 15 schools. Smoothed growth curves were estimated using the LMS method. The smoothed percentile curves for height, weight, sitting height (SH), and leg length (LL) increase rapidly during the 1st years of life and then progress slowly until 18 years. However, the sitting height-to-height ratio (SHTHR) curves decrease sharply before the age of 4 and then stabilize in both sexes. In addition, the comparison between boys and girls indicated that the values are very similar at most ages. Except during puberty, the values in boys increase (P<0.0001) for the weight, height, SH, and LL parameters and decline (P<0.0001) in the SHTHR compared to the values in girls. The growth rate curves presented two remarkable velocity peaks: the first appears during the 1st years of life and the second at puberty. Height gains at the last stage of growth (puberty) are around 15.45% of final height for boys and 15.52% for girls. This study showed a number of discrepancies for certain age groups when comparing the median weight and height values with those of the World Health Organization, the National Center for Health Statistics, and Algerian references in both sexes. Conclusion: The smoothed percentile curves for weight and height will be useful to access the general growth of Tunisian children. Furthermore, the SH, LL, and SHTHR curves can be used to monitor body proportions during childhood.

First reference curves of waist circumference and waist-to-height ratio for Tunisian children.

ABDOMINAL OBESITY FOR CHILDREN: Waist circumference (WC) and waist-to-height ratio (WTHR) reference curves are used to assess the risk of cardiovascular disease in children. The aim of this study was to develop age- and sex-smoothed WC and WTHR reference curves for Tunisian children. Data were collected during the period 2014-2015 in a cross-sectional study including 2308 children aged 6-18 years. The percentiles of WC and WTHR were developed using the LMS method. The optimal percentiles, which are associated with the body mass index (BMI) according to International Obesity Task Force (IOTF) criteria to identify overweight/obesity and with the 0.5 boundary value of WTHR to estimate cardiovascular risk, were identified by ROC curves and the Youden index (j). The results show the smoothed percentiles of WC and WTHR reference curves for Tunisian children. A comparison of the 50th percentiles with other references showed different trends in WC values. The 75th percentiles of WC and WTHR are the optimal percentiles that correspond to both PBMI25 (the percentile linked to BMI≥25) and the 0.5 boundary value. However, the 90th percentiles correspond to PBMI30 (the percentile linked to BMI≥30) in boys and girls. CONCLUSION: The new WC and WTHR reference curves can be added to clinical tools to help specialists in pediatric and physical health to reduce cardiovascular risk in Tunisian children.

Body mass index reference curves for Tunisian children.

Body mass index (BMI) reference curves are used to assess children's health. The aim of this work is to construct BMI reference curves for Tunisian children and adolescents and compare them with local and international references. The BMI reference curves were constructed using the LMS method using data from 4358 Tunisian children (2182 girls and 2176 boys) aged 0-18 years. The result of this study presents the smoothed percentile curves of BMI on the basis of age and sex of Tunisian children. The reference curves of Tunisian children demonstrated some variations in comparison with the median percentiles with the references of the International Obesity Task Force (IOTF), the World Health Organization (WHO), and with local references from Algeria and Turkey. The prevalence study indicated that the rate of overweight has increased mainly in adolescent children. CONCLUSION: the new BMI reference curves could help pediatricians and fitness specialists to assess the nutritional status of Tunisian children and to reduce disease and obesity risks.

Influence of bio-lubricants on the orthodontic friction.

The Friction force of Stainless Steel (SS) and Nickel-Titanium (Ni-Ti) rectangular archwires against stainless steel brackets was investigated. Two types of brackets were used namely: Self-ligating brackets (SLB) and conventional brackets (CB). The friction tests were conducted on an adequate developed device under dry and lubricated conditions. Human saliva, olive oil, Aloe Vera oil, sesame oil and sunflower oil were used as bio-lubricants. The friction force was examined as a function of the ligation method and oil temperature. It is found that under oil lubrication, the friction behavior in the archwire/bracket assembly were the best. The SLB ligation was better than the conventional ligation system. The enhancement of the frictional behavior with natural oils was linked to their main components: fatty acids.

Polymorphism of HLA class II genes in Berbers from Southern Tunisia.

In this study, the HLA-DRB1 and -DQB1 molecular diversity of two Berber-speaking populations of Southern Tunisia was analysed. Genetic comparisons indicate that both populations exhibit peculiar profiles for HLA-DRB1, as they diverge significantly from most other North Africans, while being highly diversified. At the opposite, they are much less differentiated from neighbouring populations according to the HLA-DQB1 polymorphism. Overall, the HLA class II genetic structure of Arab and Berber-speaking populations from Tunisia, and of North Africa as a whole, is complex and cannot be simply explained by geographic or linguistic differentiations. The present North African genetic pool has probably been shaped by both genetic drift and the contribution of genetically heterogeneous populations during the history of settlement of North Africa.

HA-1 and HA-2 minor histocompatibility antigens in Tunisians.

Minor histocompatibility antigens (MiHAgs), such as HA-1 and HA-2, are the main targets of immune responses after allogeneic stem cell transplantation (SCT). HA-1 and HA-2 are two hematopoietic system-restricted antigens encoded, respectively, by HMHA1 and MYO1G genes. In order to estimate their frequencies in Tunisians, we performed a molecular-based allele analysis for 160 healthy and unrelated subjects. Genomic DNAs were extracted mainly by the salting out method. Single nucleotide polymorphism (SNP) genotyping assays for selected sites at HMHA1 gene (rs3764653 and rs1801284) and at MYO1G gene (rs61739531) were performed with a sequence specific primers-polymerase chain reaction (SSP-PCR) method. Statistical analysis of our results showed that the HA-2 antigen is more frequent than the HA-1 antigen in the Tunisian population because their frequencies were 97% and 57%, respectively. Allele analysis for HMHA1 gene showed that the R variant (500T-504G) was predominant in our population (64%). For the MYO1G gene, the C allele was predominant (84%). All loci were in Hardy-Weinberg equilibrium (minimum P value = 0.06). Our frequencies were close to those reported in African and Caucasian groups.

Duffy blood group system genotyping in an urban Tunisian population.

BACKGROUND: The Duffy blood group system, besides its relevance in transfusion medicine, is of major interest for population genetics. In fact, the Duffy molecule is the only red cell receptor for Plasmodium vivax, thus the fixation of FY*silent allele in western south-Saharan Africa resulted in the absence of this type of malaria in that area (for a review see Kwiatowski, Am J Hum Genet 77:171-192, 2005). For the Duffy functional role see, for example, Daniels (Vox Sanguinis 93:331-340, 2007). METHODS: Duffy blood group distribution in 115 unrelated Tunisians was determined using the polymerase chain reaction with sequence specific primer (PCR-SSP) method detecting the five allelic versions of the FY gene. The red cell antigenic FY phenotype, for each donor, was deduced through DNA analysis. The blood samples of the positive FY*X alleles were investigated by serological methods, mainly the fixation-elution technique. RESULTS: The following allele frequencies were found (after having excluded FY*X, which had frequency of 0.0174): FY*1 = 0.291 (expressed 0.260; silent 0.031); FY*2 = 0.709 (expressed 0.427; silent 0.282). The most surprising result in this work is the detection of the FY*1 silent allele, usually quite rare, in four samples (1.74%). For FY*2 silent, the predominant allele in Africans, genotyping results showed a prevalence of 29.57%. The FY locus was in Hardy-Weinberg equilibrium in the present sample. CONCLUSION: When compared with European and African data, Tunisian samples demonstrated the presence of the common signs of these two ancestries (FY*2 and FY*X for the first population; and FY*2 silent for the last one). These data confirm the mixed roots of this urban Tunisian population already suggested by numerous studies on other haematological markers.

The contribution of HLA class I and II alleles and haplotypes to the investigation of the evolutionary history of Tunisians.

The frequencies of HLA class I and class II alleles and haplotypes of 104 healthy unrelated Tunisians were analyzed by high-resolution PCR-reverse dot blot hybridization, and was compared with other Mediterranean and Sub-Saharan Africans using genetic distances measurements, Neighbor-joining dendrograms, correspondence, and extended haplotypes analysis. The most frequent HLA class I A alleles were A*02, A*24, and A*30, while the most frequent B alleles were B*44, followed by B*50, B*51, and B*07. Among HLA class II DRB alleles analyzed, the most frequent were DRB1*0301, DRB1*0701, DRB1*1501, followed by DRB1*1303 and DRB1*0102; for DQB1, they were DQB1*0301 and DQB1*0201. Three-locus haplotype analysis revealed that A*03-B*07-DRB1*1503 and A*02-B*44-DRB1*0402 were the most common HLA class I and II haplotypes in this population. Compared with other communities, our result indicate that Tunisians are very related to North Africans and Western Europeans, particularly Iberians, and that Tunisians, Algerians, and Moroccans are close to Berbers suggesting little genetic contribution of Arabs who populated the area in 7th to 8th century AD. The similarities and differences between Tunisians and neighboring and related communities in HLA genotype distribution provide basic information for further studies of the MHC heterogeneity among Mediterranean and North African countries, and as reference for further anthropological studies.

HLA class II genetic diversity in southern Tunisia and the Mediterranean area.

North Africa is populated by many Arab- and Berber-speaking populations whose genetic history is still poorly understood. In this study, we analyse the HLA-DRB1 and DQB1 molecular diversity in three populations from the south of Tunisia--Berbers from Jerba, Berbers from Matmata and Arabs from Gabes--and we compare them to a large set of populations from the whole Mediterranean region. Among the three populations studied, the Berbers from Jerba are the most peculiar, as they diverge significantly from other North Africans while being genetically highly diversified and close to populations from the Near East. Thus, Jerba may have been a crossing point, in historical times, where colonization from the eastern Mediterranean area left significant genetic traces. By contrast, the populations from Matmata and Gabes are genetically similar to other Arab and Berber-speaking populations from different areas of the Maghrib, despite some peculiar allele and haplotype frequencies. At a larger scale, northwest Africa and southwest Europe are closely related according to these polymorphisms, while the populations from the eastern Mediterranean area are much more differentiated. The close genetic relatedness found for HLA among populations of the western Mediterranean region challenges previous results based on Y chromosome analyses, where the Gibraltar Strait appeared to constitute a main genetic barrier.

HLA genes in Southern Tunisians (Ghannouch area) and their relationship with other Mediterraneans.

South Tunisian HLA gene profile has studied for the first time. HLA-A, -B, -DRB1 and -DQB1 allele frequencies of Ghannouch have been compared with those of neighboring populations, other Mediterraneans and Sub-Saharans. Their relatedness has been tested by genetic distances, Neighbor-Joining dendrograms and correspondence analyses. Our HLA data show that both southern from Ghannouch and northern Tunisians are of a Berber substratum in spite of the successive incursions (particularly, the 7th-8th century A.D. Arab invasion) occurred in Tunisia. It is also the case of other North Africans and Iberians. This present study confirms the relatedness of Greeks to Sub-Saharan populations. This suggests that there was an admixture between the Greeks and Sub-Saharans probably during Pharaonic period or after natural catastrophes (dryness) occurred in Sahara.

Prevalence of C282Y and H63D mutations in the haemochromatosis (HFE) gene in Tunisian population.

The studies of the HFE mutations: H63D and C282Y in North African populations have revealed the extreme rarity or even the absence of the C282Y mutation. We have examined 1140 chromosomes (570 Tunisian people) for the presence of the two HFE mutations by PCR-RFLP analysis. We have found that the allele frequencies are, respectively, 15.17% (+/-2.1%) for the H63D and 0.09% (+/-0.17%) for the C282Y. These results are consistent with the worldwide spread of the H63D mutation and the north European restriction of the C282Y. This study will be completed by determining whether homozygote trait for H63D and associated risk factors (beta thalassémia) can lead to iron overload in Tunisia.

HLA polymorphism in type 1 diabetes Tunisians.

Several studies of the association between HLA and type 1 diabetes have been carried out revealing differences between ethnic groups. Our study, as part of the studies that should be performed about this association in the rest of the word, aims at elucidating the HLA DRB1, DQB1 polymorphism in Tunisian type 1 diabetes. This study includes 43 unrelated type 1 diabetes patients, and their mean age at onset is less than 15 years. Analysis of the frequency of alleles and haplotypes in these subjects, compared to a reference group (n = 101) led to the following results. 1) The Tunisian insulin-dependent diabetics present similarities as well as differences with other ethnic groups (Caucasians, North Africans). 2) The haplotype DRB1*04 DQ*0302 and DRB1*03 DQB1*0201 is positively associated to type 1 diabetes. 3) The heterozygotic genotype DRB1*04 DQB1*0302 / DRB1*03 DQB1*0201 is strongly associated to type 1 diabetes. 4) The haplotypes DRB1*01501 DQB1*0602 and DRB1*11 DQB1*0301 proved to be protective. In addition, the study of the subtypes DRB1*04 showed that alleles DRB1*0405 predispose to type 1 diabetes, whereas the allele DRB1*0403, which is in linkage disequilibrium with the DQB1*0402 in the Tunisian population, has a protective effect.

Antigenicity and immunogenicity of the HIV-1 gp41 epitope ELDKWA inserted into permissive sites of the MalE protein.

The highly conserved amino acid sequence ELDKWA of HIV-1 gp41 has been inserted into Escherichia coli MalE protein which had been shown to be an adequate carrier to present foreign epitopes to the immune system. We first investigated whether eight different permissive sites of MalE are able to tolerate an insertion of 7-50 residues encoding this epitope. Secondly, antigenicity of the epitope inserted in MalE protein was estimated from monoclonal antibody 2F5 binding analysis using the BIAcore(R) technology and its immunogenicity in mice was measured as the ability of hybrid proteins to elicit antibodies against a synthetic peptide containing this epitope. This study revealed a good correlation between the antigenicity of the inserted epitope and its immunogenicity. Increasing the length of the inserted epitope, as well as inserting multicopies of this epitope increased both its antigenicity and immunogenicity. However, none of the MalE hybrid proteins tested induced anti-HIV-1 neutralizing antibodies. This study strongly suggests that the capacity of the 2F5 epitope to induce neutralizing antibodies depends on the molecular context in which it is presented.

Intranasal delivery of recombinant parvovirus-like particles elicits cytotoxic T-cell and neutralizing antibody responses.

We previously demonstrated that chimeric porcine parvovirus-like particles (PPV:VLP) carrying heterologous epitopes, when injected intraperitoneally into mice without adjuvant, activate strong CD4(+) and CD8(+) T-cell responses specific for the foreign epitopes. In the present study, we investigated the immunogenicity of PPV:VLP carrying a CD8(+) T-cell epitope from the lymphocytic choriomeningitis virus (LCMV) administered by mucosal routes. Mice immunized intranasally with recombinant PPV:VLP, in the absence of adjuvant, developed high levels of PPV-specific immunoglobulin G (IgG) and/or IgA in their serum, as well as in mucosal sites such as the bronchoalveolar and intestinal fluids. Antibodies in sera from mice immunized parenterally or intranasally with PPV:VLP were strongly neutralizing in vitro. Intranasal immunization with PPV:VLP carrying the LCMV CD8(+) T-cell epitope also elicited a strong peptide-specific cytotoxic-T-cell (CTL) response. In contrast, mice orally immunized with recombinant PPV:VLP did not develop any antibody or CTL responses. We also showed that mice primed with PPV:VLP are still able to develop strong CTL responses after subsequent immunization with chimeric PPV:VLP carrying a foreign CD8(+) T-cell epitope. These results highlight the attractive potential of PPV:VLP as a safe, nonreplicating antigen carrier to stimulate systemic and mucosal immunity after nasal administration.

Subcloning of a DNA fragment encoding a single cohesin domain of the Clostridium thermocellum cellulosome-integrating protein CipA: purification, crystallization, and preliminary diffraction analysis of the encoded polypeptide.

An Escherichia coli clone encoding a single cohesin domain of the cellulosome-integrating protein CipA from Clostridium thermocellum was constructed, and the corresponding polypeptide was purified, treated with papain, and crystallized from a PEG 8000 solution. Crystals exhibit orthorhombic symmetry, space group P2(1)2(1)2(1), with cell dimensions a = 37.7 A, b = 80.7 A, c = 93.3 A, and four or eight molecules in the unit cell. The crystals diffract X-rays to beyond 2 A resolution and are suitable for further crystallographic studies.

HLA class II gene polymorphism in Tunisians.

The polymorphism of HLA class II genes (HLA-DRB, DQB, DPB) was investigated in 101 Tunisians using polymerase chain reaction. (PCR) amplification and reverse dot blot (RDB) hybridization. Allele and haplotype frequencies, as well as DRB1-DQB1 linkage disequilibria, were calculated. A total of 26 DRB1 alleles were detected and the most prevalent variant was DRB1*0301 with an allelic frequency at 21.87%. In the DR1 group, DRB1*0102 was most frequent than DRB1*0101. In the DR4 group, DRB1*0403 was the most common allele and was associated with DQB1*0402. Interestingly this DRB1-DQB1 association has not been observed in other populations. With regard to the DR8 group, DRB1*0804 was the unique variant detected, whereas with the DR13 specificity, the most common variant was DRB1*1303 in Algerians also. Although the DQB1 polymorphism analysis showed an allelic distribution very close to that observed in caucasoids, many DRB1-DQB1 associations which have not been reported in studies of other populations, were described. Finally at the DPB1 locus DPB1*1701 and *1301 allele frequencies distinguish clearly this Tunisian sample from a French caucasoïd panel of 83 subjects. In conclusion, a specific distribution of HLA components in terms of gene and haplotype frequencies characterizises this Tunisian population. This specific pattern may reflect the great ethnic diversity of this community. All these informations may be helpful in the future for HLA and disease association studies.

[Study of class I HLA polymorphism in the Tunisian population]. / Etude du polymorphisme HLA de classe I dans la population tunisienne.

The HLA class I gene polymorphism (HLA-A, -B) was investigated in a population of 102 Tunisians. Allele and haplotype frequencies as well as linkage disequilibrium between HLA-A and HLA-B loci were calculated and compared with other populations. The most frequent alleles were A2 (23%), A30 (12.5%), A3 (10.2%), A1 (8.5%), A23 (7.4%) for the HLA-A locus and B21 (14.3%), B44 (11.4%), B35 (9.6%), B5 (8.5%) for the HLA-B locus. The most frequent haplotype was A3 B21 (2.6%) and a positive linkage disequilibrium was found for the following allelic associations: A11 B35 (X2 = 6.8), A28 B35 (X2 = 5.3), and A30 B35 (X2 = 5). In conclusion, a specific distribution of HLA class I components in terms of antigen and haplotype frequencies characterizes the Tunisian population. This specific pattern may reflect the great ethnical diversity of this community. All these informations may be helpful in the future for HLA and disease association studies.