Identification of G2607A mutation in EGFR gene with a significative rate in Moroccan patients with nasopharyngeal carcinoma.

The epidermal growth factor receptor (EGFR) is involved in the regulation of several cellular processes and in the development of many human cancers. Somatic mutations of EGFR at tyrosine kinase domain have been associated with clinical response to tyrosine kinase inhibitors (TKIs) in lung cancer patients. In this study, we evaluated the frequency of point mutations in EGFR for future use of TKI in clinical treatment of nasopharyngeal carcinoma (NPC). Sixty Moroccan patient specimens of NPC were analysed for EGFR mutations in the region delimiting exons 18 and 21 by direct sequencing. Our results showed the absence of mutations in the EGFR kinase domain in these exons in all 60 analysed specimens. Sequence analysis of the EGFR—TK domain, revealed the presence of (G2607A) polymorphism at exon 20. The genotypes AA and GA were found respectively in 39 (65%) and 16 (26.6%) cases. Statistical analysis showed no difference between the polymorphism and either gender or age of patients. Mutations in EGFR kinase domain are rare events in NPC biopsies, suggesting, that treatment of NPC patients with TKI may not be effective. However, EGFR G2607A polymorphism at exon 20 is frequent in NPC cases and could be associated to clinical response to TKI therapy.

[Apolipoprotein E and angiotensin-converting enzyme gene polymorphisms as risk factors of coronary disease]. / Implication du polymorphisme génétique de l'apolipoprotéine E et de l'enzyme de converstion de l'angiotensine dans l'athérosclérose coronarienne.

The objective of this study was to test the hypothesis that apo E (RFLP, HhaI) and/or angiotensin-converting enzyme (ACE) (ins16del) are associated with higher risk for coronary heart disease. We investigated 250 patients who underwent complete cardiac examination comprising coronary angioplasty and biological analysis (CT, HDLc, LDLc, TG, apo A and apo B). Prevalence of the alleles of apo E and ACE was assessed by molecular analysis. Patients without stenosis or with non-significant stenosis (> 50% of the vascular lumen) were used as reference group (141 patients). Those presenting a significant stenosis of the coronary artery (. 50% of the vascular lumen) were considered as cases (109 patients). The relative frequency of the e 4 allele was significantly higher in cases than in reference group (p > 0.02). A strong association have been found between coronary heart disease and apo E polymorphism (2 = 8.91; p > 0.05). The presence of the e 4 allele increase the risk of atherosclerosis (RR = 2.71; IC95%: 1.25-5.90; p > 0.02) compared to e 3 allele. Also, subjects with D allele were more frequent in cases than in reference group (p > 0.001). A significant association was noted between ACE polymorphism and coronary heart disease (2 = 42.15; p > 0.001). This relationship was positive (rho de Spearman = 0.39; p > 0.01). With D/D homozygotes patients, the RR for coronary heart disease was 19.10 (p > 0.001), while The RR with I/D heterozygotes was 6.91 (p > 0.001) compared to I/I homozygotes. A significant interaction have been shown up between D/D genotype and arterial hypertension (HTA) (2 de Wald = 16.10; p > 0.001). The multivariate analysis showed that the chronic smoking, diabetes, hypoapolipoproteinemia A, interactive effects between D/D and HTA, I/D and obesity, and between D/D and hypertriglyceridemia were the major significant factors to take into consideration in our population. We also note that subjects with both D and e 4 alleles were presenting a high risk to coronary heart disease (RR = 5.93; IC95%: 2.00-17.55; p > 0.01). Thus, those two alleles (4 and D) appears to be important cardiovascular risk factors in the moroccan population.

[Polymorphism of six Alu-insertions in residents of Morocco: comparative study in Arab and Berber populations and residents of Casablanca]. / Polimorfism shesti Alu-insertsii u zhitelei Marokko: sravnitel'noe izuchenie v populiatsiiakh Arabov, Berberov i zhitelei Kasablanki.

Alu elements are the largest family of short tandem interspersed elements (SINEs) in human who have arisen to a copy number with an excess of 500,000 copies per haploid human genome and mobilize through an RNAse polymerase III derived transcript in a process termed "retroposition." Several features make Alu insertions a powerful tool used in population genetic studies: the polymorphic nature of many Alu insertions, the stability of an Alu insertion event and, furthermore, the ancestral state of an Alu insertion is known to be the absence (complete and exact) of the Alu element at a particular locus and the presence of an Alu insertion at the site that forward mutational change. Here we report on the distribution of six polymorphic Alu insertions in a general Moroccan population and in the Arab and Berber populations from Morocco and their relationships with other populations previously studied. Our results show that there is a small difference between Arabs and Berbers and that the Arab population was closer to African populations than Berber population which is closest to Europeans.

[Homocysteine, lipoprotein (a): risk factors for coronary heart disease]. / Homocystéine, lipoprotéine (a): acteurs de risque de l'athérosclérose coronarienne.

Our data suggest that the hyperhomocysteinemia and/or increased plasma level of lipoprotein Lp(a) are risk factors for coronary heart disease. We investigated 178 patients who underwent complete cardiac examination comprising coronary angiography and biological analysis (CT, HDL-c, LDL-c, TG, and apoAI, apoB, homocysteine and Lp(a)). Patients presenting a significant stenosis of the coronary artery ( 50% of the vascular lumen) were considered as cases (113 patients). Those without stenosis or with non-significant stenosis (< 50% of the vascular lumen) were used as controls (65 subjects). Homocysteinemia was significantly higher in cases than in control subjects (8.26 mol/L (2.34 versus 17.85 (2.34, p < 0.001). A strong association between coronary heart disease and homocystein has been found (Eta(2) = 0.76). The OR were 0.16 when homocystein level was lower than 15 mol/L, and 27.78 when homocysteine level was upper than or equal to 15 mol/L. The RR was 5.16 (95% IC = 3.66-6.66, p < 0.001). Even though there was a significant correlation between tabagic impregnation and homocysteinemia (Spermann's rho = 0.37, p < 0.05), there was no interactive effect between these two factors and coronary disease (Wald khi2 = 0.086, p > 0.05). Therefore, no association was found between homocyteinemia and other coronary heart disease risk factors. The Lp(a) levels were significantly higher in cases than in controls subjects (188 (84 mg/L in control subjects versus 590 (199 in cases, p < 0.001). A stronger relationship was noted between coronary heart disease and Lp(a) (Eta (2) = 0.66). The OR were 0.09 when lipoprotein (a) levels were lower than 350 mg/L, and 5,88 when Lp(a) levels were higher than or equal to 350 mg/L. The estimate RR was 6.47 (95% IC = 4.39-8.55, p < 0.001). The level of Lp(a) was positively correlated with the severity of coronary heart disease (Spermann's rho = 0.95, p < 0.001). A weak correlation between Lp(a) and LDL-c was observed (Spermann's rho = 0.12, p = 0.048). But the multivariate analysis didn't show interactive effect between these two factors and coronary disease (khi2 de Wald = 0.264, p > 0.05). No association was noted between Lp(a) and the others risk factors. Moreover, a positive correlation between the levels of homocysteine and those of Lp(a) was found (Spermann's rho = 0.54, p < 0.001). In contrast their effect on coronary heart disease seems to be independant (Wald khi2 = 2.957, p > 0.05). Thus, these two parameters appear as independant risk factors for coronary heart disease.

Cloning and sequencing of a chromosomal fragment from Clostridium acetobutylicum strain ABKn8 conferring chemical-damaging agents and UV resistance to E. coli recA strains.

A 3.3-kb DNA fragment of Clostridium acetobutylicum conferred methyl methane sulfonate (MMS), mitomycin C (MC), and UV resistance to recA strains of E. coli when cloned on the pUC19 plasmid. Analysis of the nucleotide sequence of the total insert and results of in vitro transcription-translation experiments showed that the insert directed the synthesis of three polypeptides referred to as ORFa, ORFb, and ORFc of 23.6, 15.3, and 21 kDa, respectively. None of the polypeptides presented a relationship with the RecA protein of E. coli or products of genes involved in the SOS response. The deduced amino acid sequence of ORFb and ORFc are highly homologous to those deduced from two genes specifying resistance to tellurium salts present on plasmid pMER610 harbored by Alcaligenes sp.strains and to an AMP-binding protein (CABP1) found in Dictyostelium discoideum. The existence of these homologous proteins suggests that they may perform a similar key function in the three unrelated organisms.

Nucleotide sequence analysis of two 5-nitroimidazole resistance determinants from Bacteroides strains and of a new insertion sequence upstream of the two genes.

DNA sequence analysis of regions from plasmid pIP417 and chromosome BF8 which encode 5-nitroimidazole resistance in Bacteroides strains allowed the identification of two open reading frames corresponding to new genes, nimA (528 bp) and nimB (492 bp). Either gene may confer 5-nitroimidazole resistance to susceptible strains of Bacteroides. The encoded polypeptides have deduced molecular masses of 20.1 and 18.6 kDa, respectively, and share about 73% identity and 85% similarity. A new insertion sequence (IS) element named IS1168 lies 14 bases upstream of the nimA gene. The complete sequence of IS1168 was determined. A similar IS exists 12 bp upstream of the nimB gene. About 60% of the BF8 IS element was also sequenced and shown to be almost identical to IS1168.

Characterization of restriction endonuclease BfrBI from Bacteroides fragilis strains BE3 and AIP 10006.

A new type II restriction endonuclease, named BfrBI, was detected in two strains of Bacteroides fragilis, BE3 and AIP 10006 (NCTC 9343T). The enzyme BfrBI, an isoschizomer of NsiI and AvaIII, recognized the hexanucleotide sequence [5'-ATG decreases CAT-3'], with a cleavage site generating blunt ends.

Stable inheritance of shuttle vectors based on plasmid pIM13 in a mutant strain of Clostridium acetobutylicum.

New shuttle vectors for Clostridium acetobutylicum were constructed, using as replicons the Gram-positive plasmid pIM13, and derivatives of the Gram-negative plasmid pBR322, including pUC19. These vectors transformed C. acetobutylicum at a high frequency (up to 10(6) transformants per microgram DNA) by PEG-mediated protoplast transformation. A mutant host strain, NI-4082, was isolated on the basis of its ability to maintain plasmid pIM13 stably in the absence of selection pressure. The shuttle vectors showed no segregational or structural instability in this mutant strain. Moreover, the results suggested a relationship between segregational instability and the multimerization of pIM13 in C. acetobutylicum. The host/vector system described possessed all the properties required for efficient gene cloning in this species.

Recognition sequence of a new methyl-specific restriction system from Clostridium acetobutylicum strain ABKn8.

A new type II restriction endonuclease, named Cac8I was detected in Clostridium acetobutylicum strain ABKn8. Cac8I cleaved the hexanucleotide sequence [5'-GCN decreases NGC-3'] and generated blunt ends. Up to now no isoschizomer of Cac8I has been described [corrected].

Characterization of a methyl-specific restriction system in Clostridium acetobutylicum strain N1-4081.

A type II restriction endonuclease, named CacI, was detected in Clostridium acetobutylicum strain N1-4081. CacI cleaved the tetranucleotide sequence [5' decreases -GATC-3']. The modification system consisted of the methylation of the adenine present in this sequence. CacI, an isoschizomer of MboI, is inactive on dam methylated substrates.