👤 Ndeye Coumba Ndiaye

In this paper, we present the design of a new automatic fluorescence monitoring system (AUTOFLUO) for real-time control of pesticide contamination in natural waters. This system was used to analyse two fluorescent pyrethroid insecticides, phenothrin (PHE) and permethrin (PER), currently used in the Niayes agricultural district in Senegal. The results were then compared with those obtained using the classical fluorescence method (FLUO). The analytical parameters (λex, λem, and pH) were optimised. Phenothrin exhibits maximum excitation and emission wavelengths of 221 and 321 nm, respectively, whereas permethrin has these values at 210 and 297 nm. The optimum pH value was determined to be 7 for PHE and 8 for PER. The linearity of both the calibration and standard addition curves was validated through variance analysis. A Student's t-test demonstrated that the intercept values of the calibration curves were not significantly different from zero (p > 5 %). The limit of detection (LOD) ranges from 0.02 to 5.16 ng mL Show less

Melanoma is an aggressive skin cancer that can rapidly metastasize to become fatal, if not diagnosed early. Despite recent therapeutic advances, management of melanoma remains difficult. Therefore, novel molecular targets and strategies are required to manage this neoplasm. This study was undertaken to determine the role of the sirtuin SIRT6 in melanoma. Employing a panel of human melanoma cells and normal human melanocytes, we found significant SIRT6 mRNA and protein upregulation in melanoma cells. Further, using a tissue microarray coupled with quantitative Vectra analysis, we demonstrated significant SIRT6 overexpression in human melanoma tissues. Lentiviral short hairpin RNA-mediated knockdown of SIRT6 in A375 and Hs 294T human melanoma cells significantly decreased cell growth, viability, and colony formation, induced G1-phase arrest and increased senescence-associated beta-galactosidase staining. As autophagy is important in melanoma and is associated with SIRT6, we used a qPCR array to study SIRT6 knockdown in A375 cells. We found significant modulation in several genes and/or proteins (decreases in AKT1, ATG12, ATG3, ATG7, BAK1, BCL2L1, CLN3, CTSB, CTSS, DRAM2, HSP90AA1, IRGM, NPC1, SQSTM1, TNF, and BECN1; increases in GAA, ATG10). Our data suggests that increased SIRT6 expression may contribute to melanoma development and/or progression, potentially via senescence-and autophagy-related pathways. Show less

Vascular endothelial growth factor (VEGF) is an angiogenic and neurotrophic factor, secreted by endothelial cells, known to impact various physiological and disease processes from cancer to cardiovascular disease and to be pharmacologically modifiable. We sought to identify novel loci associated with circulating VEGF levels through a genome-wide association meta-analysis combining data from European-ancestry individuals and using a dense variant map from 1000 genomes imputation panel. Six discovery cohorts including 13,312 samples were analyzed, followed by in-silico and de-novo replication studies including an additional 2,800 individuals. A total of 10 genome-wide significant variants were identified at 7 loci. Four were novel loci (5q14.3, 10q21.3, 16q24.2 and 18q22.3) and the leading variants at these loci were rs114694170 (MEF2C, P = 6.79 x 10(-13)), rs74506613 (JMJD1C, P = 1.17 x 10(-19)), rs4782371 (ZFPM1, P = 1.59 x 10(-9)) and rs2639990 (ZADH2, P = 1.72 x 10(-8)), respectively. We also identified two new independent variants (rs34528081, VEGFA, P = 1.52 x 10(-18); rs7043199, VLDLR-AS1, P = 5.12 x 10(-14)) at the 3 previously identified loci and strengthened the evidence for the four previously identified SNPs (rs6921438, LOC100132354, P = 7.39 x 10(-1467); rs1740073, C6orf223, P = 2.34 x 10(-17); rs6993770, ZFPM2, P = 2.44 x 10(-60); rs2375981, KCNV2, P = 1.48 x 10(-100)). These variants collectively explained up to 52% of the VEGF phenotypic variance. We explored biological links between genes in the associated loci using Ingenuity Pathway Analysis that emphasized their roles in embryonic development and function. Gene set enrichment analysis identified the ERK5 pathway as enriched in genes containing VEGF associated variants. eQTL analysis showed, in three of the identified regions, variants acting as both cis and trans eQTLs for multiple genes. Most of these genes, as well as some of those in the associated loci, were involved in platelet biogenesis and functionality, suggesting the importance of this process in regulation of VEGF levels. This work also provided new insights into the involvement of genes implicated in various angiogenesis related pathologies in determining circulating VEGF levels. The understanding of the molecular mechanisms by which the identified genes affect circulating VEGF levels could be important in the development of novel VEGF-related therapies for such diseases. Show less

The association of genetic profiles with biological or clinical assessments is not clearly established especially among apparently healthy subjects. A multivariate statistical analysis was performed on 24 polymorphisms related to the main metabolic pathways involved in cardiovascular diseases (CVDs). They were collected among 1551 healthy subjects of the Stanislas cohort to obtain genetic profiles. Association with biological variables was then studied at baseline (t0) and 5 years later (t5). Six genetic clusters were identified with relevant profiles and five polymorphisms from the selectin, apolipoprotein C3 and lipoprotein lipase genes (SELE-98G/T, APOC3-3175C/G, APOC3-482C/T, APOC3-1100C/T, LPL-93T/G) were sufficiently characteristic to associate 99.6% of the subjects with their corresponding cluster. A 5-year follow-up showed that clinical and biological measurements in relation to CVD risk factors already differ with triglyceride (p=0.009 for t0 and p=0.005 for t5) and high-density lipoprotein cholesterol (p=0.014 for t0 and p=0.003 for t5) for these previous genetic clusters. This study presents the hypothesis that SELE could be protective, whereas APOC3 could be associated with risk. It remains to be seen whether these polymorphisms will be predictive of CVD events among the selected clusters of different metabolic subtypes after a 10-year follow-up. Show less