Lack of association between human leukocyte antigen-E alleles and nasopharyngeal carcinoma in Tunisians

Nasopharyngeal carcinoma (NPC), a cancer with a remarkable geographical and worldwide ethnic distribution, has been strongly associated with human leukocyte antigen (HLA) class I genes. The presence of additional HLA risk factors has been suggested by several reports. In the present study, we analyzed the implication of HLA-E gene polymorphisms in NPC susceptibility in Tunisians, a population characterized by an intermediate incidence of NPC with specific clinical features. Peripheral blood DNA was obtained from 185 patients with NPC and 177 matched controls. Genotyping for three single-nucleotide polymorphisms, codon 83Gly/Arg, codon 157Arg/Gly, and codon 107Arg/Gly, was performed using the polymerase chain reaction method. The HLA-E*01:01 and HLA-E*01:03 were the only alleles found among Tunisians. The HLA-E*01:03 allele had a slight increase in patients with NPC (43%) compared with controls (37%), but the difference did not reach a statistical significance. Our results show the lack of association between HLA-E alleles and NPC in the Tunisian population. This is not in agreement with the previous studies, suggesting a potential implication of HLA-E gene polymorphisms in the susceptibility to NPC among populations with high-risk incidence. Our study further supports the dissimilarity of NPC between populations with different NPC incidence.     

Nodule thyroïdien bénin fixant le 99mTc-MIBI

ObjectivesTo illustrate a case of intense uptake of ^99mTc-MIBI on benign thyroid nodule and to recall the mechanisms of this uptake.Case presentationA patient of 25 years old had a parathyroid scintigraphy for suspected right lower parathyroid adenoma. The exam showed intense uptake of ^99mTc-MIBI at the infero-lateral region of the right thyroid lobe. Low levels of PTH prompted to perform a thyroid scintigraphy for better diagnostic orientation. The scan revealed a large cold right basilobar thyroid nodule. The patient underwent a right loboisthmectomy. The histological analysis found a 3 cm diameter vesicular adenoma with oncocytic cells of the lower pole of right thyroid lobe.Discussion/conclusion^99mTc-MIBI is used in the imaging of hyperparathyroidism. Radiotracer uptake is correlated to the parathyroid adenoma content in oxyphil cells. These cells are rich in mitochondria and retain the ^99mTc-MIBI. This radiotracer can bind also on thyroid nodules. The specificity of this uptake for the diagnosis of malignancy is low. It is relevant to the nodule's wealth in oncocytic cells. These cells possess numerous mitochondria and can sequester ^99mTc-MIBI like parathyroid oxyphil cells.     

Phytoplankton distribution in the upwelling areas of the Moroccan Atlantic coast localized between 32°30'N and 24°N

Marine phytoplankton was studied in January and July 2002 along of four transects: 32°30′N, 29°N, 24°30′N and 24°N. A total of 142 taxa were recorded in this area. The maximal specific richness, both in summer and in winter, was registered around Dakhla (24°N). The global spatiotemporal variability of species richness and specific diversity showed that the most structured and species-rich populations are situated in the coastal areas. The vertical variation of the two parameters showed homogeneity between depth levels. The maximal phytoplanktonic densities are recorded in the southern transects due to the permanent upwelling activity in the southern Atlantic coast. The bathymetric distribution of densities was more heterogeneous during summer, characterized by a high intensity of upwelling. The species Thalassionema nitzschioides, Asterionellopsis glacialis, Melosira, Chaetoceros and Leptocylindrus minimus are indicators of upwelling.     

Lack of Enantioselectivity in the SULT1A3‐catalyzed Sulfoconjugation of Normetanephrine Enantiomers: An In Vitro and Computational Study

(1R)‐Normetanephrine is the natural stereoisomeric substrate for sulfotransferase 1A3 (SULT1A3)‐catalyzed sulfonation. Nothing appears known on the enantioselectivity of the reaction despite its potential significance in the metabolism of adrenergic amines and in clinical biochemistry. We confronted the kinetic parameters of the sulfoconjugation of synthetic (1R)‐normetanephrine and (1S)‐normetanephrine by recombinant human SULT1A3 to a docking model of each normetanephrine enantiomer with SULT1A3 and the 3′‐phosphoadenosine‐5′‐phosphosulfate cofactor on the basis of molecular modeling and molecular dynamics simulations of the stability of the complexes. The K_M, V_max, and k_cat values for the sulfonation of (1R)‐normetanephrine, (1S)‐normetanephrine, and racemic normetanephrine were similar. In silico models were consistent with these findings as they showed that the binding modes of the two enantiomers were almost identical. In conclusion, SULT1A3 is not substrate‐enantioselective toward normetanephrine, an unexpected finding explainable by a mutual adaptability between the ligands and SULT1A3 through an “induced‐fit model” in the catalytic pocket. Chirality, 25:28‐34, 2012.© 2012 Wiley Periodicals, Inc.     

Fixation extraosseuse du radiotraceur lors de la réalisation d’une scintigraphie du squelette chez un patient atteint de bêta-thalassémie : à propos d’un cas

Red blood cell transfusion, main therapeutic modality of beta-thalassemia, leads to iron overload which may perturb several metabolic ways. The aim of this paper is to illustrate the uptake abnormalities observed on bone scan of thalassemic patients and to discuss mechanisms of extraosseous accumulation of the radiopharmaceutical in this pathology. We report a 16-year-old child suffering from beta-thalassemia major undergoing transfusion therapy. A bone scan was indicated to look for osseous infection. This study revealed a little skeletal uptake and abnormal liver, splenic and renal accumulation. A repeat bone scan, performed three weeks later showed a better skeletal uptake which enabled the discovery of focal abnormalities and made the diagnostic easier. The effect of iron overload on radiopharmaceuticals's uptake in bone scan is known since 1975. Dissociation of ^99mTc from the carrier ligand due to the presence of iron excess seems the most plausible hypothesis. Free ^99mTc can be bound to other tissular substrates which can explain extraosseous uptake. The normally available pool for bone is reduced and then the skeletal uptake decreased. This report limits considerably the sensitivity of the bone scan. A well-led iron chelation and eventually the use of diuretic drug may guarantee a better quality of bone scan images.     

Comparative 2-DE proteomic analysis of date palm (Phoenix dactylifera L.) somatic and zygotic embryos

Two-dimensional gel electrophoresis coupled to mass spectrometry has been used to compare the proteome of date palm (Phoenix dactylifera L. cv. Deglet Nour) zygotic and somatic embryos. Proteins were trichloroacetic acid–acetone–phenol extracted, quantified, and resolved by 2-DE in the 5 to 8 pH range. Total protein content and number of resolved spots were higher in zygotic (110 ± 14.5 mg/g DW; 349 spots) than in somatic (70.96 ± 4.8 mg/g DW; 210 spots) embryos. The 2-DE map of both systems showed qualitative (263) and quantitative (72) differences. Statistical analysis of spot intensity was performed by PCA, obtaining two accurate groupings of the samples and determining the most discriminating spots. Samples were also clustered using Euclidean distance with average linkage algorithm of the Genesis software package. Sixty-three variable spots were subjected to mass spectrometry analysis, resulting in 23 identifications. Identified proteins were classified in the following functional categories; glycolysis (8 proteins), citrate cycle (1), ATP synthesis (1), carbohydrate biosynthesis (2), amino acids metabolism (1), stress related (4), storage (3), and with no function assigned for three of them. Most of the somatic embryo specific proteins identified belonged to glycolysis pathways, whereas those of the zygotic embryo to storage and stress-related proteins. Differences are discussed in terms of metabolism and biology of both types of embryos.     

Taxonomy of mycelial actinobacteria isolated from Saharan soils and their efficiency to reduce aflatoxin B1 content in a solid-based medium

Aflatoxin B1 (AFB1) is a carcinogenic compound produced by filamentous fungi. In order to reduce AFB1 occurrence in foodstuffs, 13 strains of mycelial actinobacteria were tested in vitro for the efficacy to reduce AFB1 content; all were isolated from the Saharan soils of Algeria. Firstly, morphological study and molecular analysis, based on the 16S rRNA gene, indicated that these strains belong to Actinomadura, Nocardiopsis, Nonomuraea, Saccharothrix and Streptomyces genera. Secondly, each strain’s efficacy to reduce pure AFB1 content was studied in ISP2-medium. After a 4-day incubation at 30°C on AFB1-supplemented medium (5 ppm of AFB1), AFB1 was extracted and quantified. AFB1 content was reduced by all strains (42.9–97.6%). The three most efficient reducers (94.9–97.6%) were two strains belonging to the genus Streptomyces and one to the genus Saccharothrix. Among the latter, strains ACD6 and ABH19 showed no adsorption mechanism involved, suggesting a potential degradation mechanism. These findings led us to suggest that these actinobacterial strains could be used as decontamination treatments for the reduction of AFB1 content.     

Chloroplast DNA analysis in Tunisian fig cultivars (Ficus carica L.): Sequence variations of the trnL-trnF intergenic spacer

We investigated the nucleotide variation of a non-coding, chloroplast DNA (cpDNA) region to infer relationships among Tunisian fig cultivars. In this study, we examine the level of genetic diversity and its distribution using sequences of the trnL and trnF genes intergenic spacer. The non-coding region displays 28 substitution sites. Insertions and deletions involving 6 sites were found. By using the Kimura-2 method, nucleotide sequences have been aligned using the MEGA program to calculate pairwise divergence of trnL-trnF spacer sequences between cultivars. The size of this non-coding region varied from 430 to 464 bases. The relatively high A + T values (63.7–64.4%) of trnL-trnF intergenic spacer in Ficus carica may explain the high proportion of the identified transversions (t_i/t_v = 0.9). These results suggest the occurrence of nucleotide diversity with a large variation level of chloroplast non-coding region. The analysed data illustrate a considerable level of variability in the genetic pool of the local germplasm. In fact, relationships inferred from the cpDNA analysis suggest several clades, which do not show geographical correspondence. Fourteen haplotypes were detected among 20 individuals examined, yielding a haplotype diversity of 0.983 and a high level of nucleotide diversity (0.0100). The observed variation pattern of plastid DNA provides evidence that the fig germplasm has been undergoing rapid expansion. Neutrality tests rejected the neutrality assumption in the total sample. The cytoplasm variability indicates a narrow genetic base in the cultivated common fig. Despite the high level value of the apparent diversity, we may conclude that fig chloroplast genome provides a new conceptual and practical opportunity to evaluate genetic diversity and to identify local cultivars, making it a valuable source to include into potential breeding programs.