N-terminal purification tag alters thermal stability of the carboxylesterase EstGtA2 from G. thermodenitrificans by impairing reversibility of thermal unfolding

The novel thermostable carboxylesterase EstGtA2 from G. thermodenitrificans (accession no. AEN92268) was functionally expressed and purified using an N-terminal fusion tag peptide. We recently reported general properties of the recombinant enzyme. Here we report preliminary data on thermal stability of EstGtA2 and of its tagged form. Conformational stability was investigated using circular dichroism and correlated with residual activity measurements using a colorimetric assay. The tag peptide had no considerable impact on the apparent melting temperature: T(m) value = 64.8°C (tagged) and 65.7°C (cleaved) at pH 8. After thermal unfolding, the tag-free enzyme rapidly recovered initial activity at 25°C (1.2 Umg(-1)), which was corroborated by substantial refolding (83%) as determined by far-UV CD transitions. However, after thermal unfolding, the purification tag drastically decreased specific activity at 25°C (0.07 Umg(-1)). This was corroborated by the absence of refolding transition. Although the purification tag has no undesirable impact on activity before thermal unfolding as well as on Tm, it drastically hinders EstGtA2 refolding resulting in a major loss of thermal stability.     

Spectroscopic identification of new ellagitannins and a trigalloyl-glucosylkaempferol from an extract of Euphorbia cotinifolia L. with antitumour and antioxidant activity

From an extract of leaves and small branches of Euphorbia cotinifolia L., 17 polyphenols were isolated including two new ellagitannins and a trigalloyl-glucosylkaempferol. Based on extensive spectral data (UV, ESI-MS, 1H NMR, DEPT and 1D/2D NMR) and chemical studies, their structures were characterized as 1-O-galloyl-3,6-hexahydroxydiphenoyl-D-B1,4-glucopyranose (5), 1-O-galloyl-3,6-valoneoyl-D-B1,4-glucopyranose (6), and kaempferol 3-O-(2",3",6"-tri-O-galloyl)-beta-D-glucopyranoside (13). Biological evaluation indicated that the 80% aqueous methanol extract (AME), chloroform extract (CE), and some pure compounds have potent scavenging activity in the DPPH assay with SC50 values lower than that of ascorbic acid, especially 5, 7-9, and a mixture of hyperin 6"-gallate (11) and isoquercitrin 6"-gallate (12). Moreover, using the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl-2H-tetrazolium bromide (MTT) cell viability assay, 6 and 8 exhibited the highest inhibition of human hepatocellular carcinoma cells (Hep-G2), while AME, CE, 5, 7, 9, and the mixture of 11 and 12 were found to be moderate growth inhibitors according to their IC50 values. In addition, AME, 5, and 8 exhibited significant antiproliferative activity against colon carcinoma cells (HCT-116); however, CE and the other examined compounds displayed moderate to low antitumour activity against HCT-116 cells.     

Past and future trends in cancer and biomedical research: a comparison between Egypt and the World using PubMed-indexed publications

ABSTRACT: BACKGROUND: PubMed is a free web literature search service that contains almost 21 millions of abstracts and publications with almost 5 million user queries daily. The purposes of the study were to compare trends in PubMed-indexed cancer and biomedical publications from Egypt to that of the world and to predict future publication volumes. METHODS: The PubMed was searched for the biomedical publications between 1991 and 2010 (publications dates). Affiliation was then limited to Egypt. Further limitation was applied to cancer, human and animal publications. Poisson regression model was used for prediction of future number of publications between 2011 and 2020. RESULTS: Cancer publications contributed 23% to biomedical publications both for Egypt and the world. Egyptian biomedical and cancer publications contributed about 0.13% to their world counterparts. This contribution was more than doubled over the study period. Egyptian and world's publications increased from year to year with rapid rise starting the year 2003. Egyptian as well as world's human cancer publications showed the highest increases. Egyptian publications had some peculiarities; they showed some drop at the years 1994 and 2002 and apart from the decline in the animal: human ratio with time, all Egyptian publications in the period 1991-2000 were significantly more than those in 2001-2010 (P<0.05 for all). By 2020, Egyptian biomedical and cancer publications will increase by 158.7% and 280% relative to 2010 to constitute 0.34% and 0.17% of total PubMed publications, respectively. CONCLUSIONS: The Egyptian contribution to world's biomedical and cancer publications needs significant improvements through research strategic planning, setting national research priorities, adequate funding and researchers' training.     

Temporal similarity between Candida albicans genotypes in a Tunisian neonatal intensive care unit suggests several nosocomial cross-contamination episodes

The nosocomial transmission of Candida albicans in neonatal intensive care units (NICUs) is an increasing concern and understanding the route of this transmission is critical for adequate infection control measures. The aim of our study was to assess the likeliness of nosocomial acquisition of C. albicans in the NICU of Farhat Hached hospital in Sousse (Tunisia). We genotyped 82 isolates from 40 neonates and 7 isolates from 5 health care workers (HCWs) with onychomycosis, by using CDC3 microsatellite length polymorphism (MLP) and the high-resolution melting (HRM) analysis. Combined MLP and HRM CD3 analysis led to the delineation of 12 genotypes. Five temporal clustering caused by five genotypes occurred during the study period. Three of these genotypes were isolated in both neonates and HCWs. The first clustering included 28 isolates obtained between January 2003 and May 2004 from 16 neonates and 2 HCWs. The second clustering included three isolates collected in 2004 from three neonates and two HCWs. The third clustering included 11 isolates obtained from 6 neonates and 1 HCW in 2006. The two remaining clustering could not be associated with any HCW's contamination. These results argue for the nosocomial transmission of C. albicans in our NICU. The combined MLP and HRM analysis is a rapid first approach for tracking cross-contamination.     

Maturity assessment of composted olive mill wastes using UV spectra and humification parameters

In this study, two olive mill wastes - exhausted olive cake (EOC) and paste of olive mill wastewater naturally dehydrated (POMW) - were co-composted and mixed with 25% sesame bark (SB). The humification process was evidenced by quantifying the humic substances and the generally accepted humification indices: (i) the ratio of humic acid (HA) carbon to fulvic acid (FA) carbon (CHA/CFA), (ii) the ratio of water soluble organic carbon (CW) to total organic nitrogen (Cw/Norg), (iii) and the ratio of humic acid carbon to total organic carbon CHA/Corg and by determining the absorbance ratios: E2/E4, E2/E6 and E4/E6. The results showed that the time required to reach maturity was dependant on the chemical properties of the initial raw materials used. The compost including EOC had more nitrogen and synthesised more polymerised HA, the POMW compost also had acceptable degrees of stability and maturity at the end of the process. Maturation was confirmed by a decline in Cw below 1.7, an increase in nitrogen, in HA, in CHA/CFA and an elimination of phytotoxicity. Composts produced with olive mill wastes, experimented on potato culture in the field, can be considered beneficial to soils because of their humification indexes and no toxicity.     

Microsatellite markers identify three additional quantitative trait loci for resistance to soybean sudden-death syndrome (SDS) in Essex × Forrest RILs

Resistance to the sudden-death syndrome (SDS) of soybean (Glycine max L. Merr.), caused by Fusarium solani f. sp. glycines, is controlled by a number of quantitatively inherited loci (QTLs). Forrest showed a strong field resistance to SDS while Essex is susceptible to SDS. A population of 100 recombinant inbred lines (RILs) derived from a cross of Essex × Forrest was used to map the loci effecting resistance to SDS using phenotypic data obtained from six environments. Six loci involved in resistance to SDS were identified in this population. Four of the QTLs identified by BARC-Satt214 (P = 0.0001, R²= 24.1%), BARC-Satt309 (P = 0.0001, R² = 16.3), BARC-Satt570 (P = 0.0001, R² = 19.2%) and a random amplified polymorphic DNA (RAPD) marker OEO2₁₀₀₀ (P = 0.0031, R²=12.6) were located on linkage group (LG) G (Satt309 and OEO2₁₀₀₀ were previously reported). Jointly the four QTLs on LG G explained 50% of the variation in SDS disease incidence (DI). All the QTLs on LG G derived the beneficial allele from Forrest. Two QTLs, BARC-Satt371 (P = 0.0019, R² = 12%) on LG C2 (previously reported) and BARC-Satt354 (P = 0.0015, R² = 11.5%) on LG I, derived their beneficial allele from Essex and jointly explained about 40% of the variation in SDS DI. Two-way and multi-way interactions indicated that gene action was additive among the loci underlying resistance to SDS. These results suggest that cultivars with durable resistance to SDS can be developed via gene pyramiding. Received: 19 January 2000 / Accepted: 30 April 2000     

Discovery of potent carbonic anhydrase,acetylcholinesterase, and butyrylcholinesterase enzymes inhibitors: The new amides and thiazolidine‐4‐ones synthesized on an acetophenone base

Compounds containing nitrogen and sulfur atoms can be widely used in various fields, including industry, medicine, biotechnology, and chemical technology. Among them, amides of acids and heterocyclic compounds have an important place. These amides and thiazolidine‐4‐ones showed good inhibitory action against butyrylcholinesterase (BChE), acetylcholinesterase (AChE), and human carbonic anhydrase isoforms. AChE exists at high concentrations in the brain and red blood cells. BChE is an important enzyme that is plentiful in the liver, and it is released into the blood in a soluble form. They were demonstrated to have effective inhibition profiles with K_i values of 23.76–102.75 nM against hCA I, 58.92–136.64 nM against hCA II, 1.40–12.86 nM against AChE, and 9.82–52.77 nM against BChE. On the other hand, acetazolamide showed K_i value of 482.63 ± 56.20 nM against hCA I, and 1019.60 ± 163.70 nM against hCA II. Additionally, Tacrine inhibited AChE and BChE, showing K_i values of 397.03 ± 31.66 and 210.21 ± 15.98 nM, respectively.     

Mutational spectrum of dihydropyrimidine dehydrogenase gene (DPYD) in the Tunisian population

Dihydropyrimidine dehydrogenase enzyme (DPD) deficiency is a pharmacogenetic syndrome leading to severe side-effects in patients receiving therapies containing the anticancer drug 5-fluorouracil (5-FU). The aim of this population study is to evaluate gene variations in the coding region of the dihydropyrimidine dehydrogenase gene (DPYD) in the Tunisian population. One hundred and six unrelated healthy Tunisian volunteers were genotyped by denaturing HPLC (DHPLC). Twelve variants in the coding region of the DPYD were detected. Allele frequencies of DPYD*5 (A1627G), DPYD*6 (G2194A), DPYD*9A (T85C), A496G, and G1218A were 12.7%, 7.1%, 13.7%, 5.7%, and 0.5%, respectively. The DPYD alleles DPYD*2A (IVS 14+1g>1), DPYD*3 (1897 del C) and DPYD*4 (G1601A) associated with DPD deficiency were absent from the examined subjects. We describe for the first time a new intronic polymorphism IVS 6-29 g>t, found in an allelic frequency of 4.7% in the Tunisian population. Comparing our data with that obtained in Caucasian, Egyptian, Japanese and African-American populations, we found that the Tunisian population resembles Egyptian and Caucasian populations with regard to their allelic frequencies of DPYD polymorphisms. This study describes for the first time the spectrum of DPYD sequence variations in the Tunisian population.     

Cell-type specificity of the Anabaena fdxN-element rearrangement requires xisH and xisl

The fdxN element, along with two other DNA elements, is excised from the chromosome during heterocyst differentiation in Anabaena sp. strain PCC 7120. Previous work showed that rearrangement of the fdxN element requires the xisF gene, which encodes a site-specific recombinase, and suggested that at least one other heterocyst-specific factor is involved. Here we report that the xisH and xisl genes are necessary for the heterocyst-specific excision of the fdxN element. Deletion of a 3.2 kb region downstream of the xisF gene blocked the fdxN-element rearrangement in hetero-cysts. The 3.2 kb deletion was complemented by the two overlapping genes xisH and xisl. Interestingly, extra copies of xlsHI on a replicating plasmid resulted in the xisF-dependent excision of the fdxN element in vegetative cells. Therefore, xisHI are involved in the control of cell-type specificity of the fdxN rearrangement. The xisHI genes had no effect on the two other DNA rearrangements. The xisHl-induced excision of the fdxN element produced strains lacking the element and demonstrates that the 55 kb element contains no essential genes. xisH and xisl do not show similarity to any known genes.