Evaluation of Plasma Trace Elements in Different Stages of Nonalcoholic Fatty Liver Disease

Biological Trace Element Research - Nonalcoholic fatty liver disease (NAFLD) is considered as the hepatic manifestation of metabolic syndrome. Its global prevalence is estimated between 25 and 45%,...     

Mosquito population structure,pathogen surveillance and insecticide resistance monitoring in urban regions of Crete,Greece

BackgroundIn Greece vector borne diseases (VBD) and foremost West Nile virus (WNV) pose an important threat to public health and the tourist industry, the primary sector of contribution to the national economy. The island of Crete, is one of Greece’s major tourist destinations receiving annually over 5 million tourists making regional VBD control both a public health and economic priority.MethodologyUnder the auspices of the Region of Crete, a systematic integrative surveillance network targeting mosquitoes and associated pathogens was established in Crete for the years 2018–2020. Using conventional and molecular diagnostic tools we investigated the mosquito species composition and population dynamics, pathogen infection occurrences in vector populations and in sentinel chickens, and the insecticide resistance status of the major vector species.Principal findingsImportant disease vectors were recorded across the island including Culex pipiens, Aedes albopictus, and Anopheles superpictus. Over 75% of the sampled specimens were collected in the western prefectures potentially attributed to the local precipitation patterns, with Cx. pipiens being the most dominant species. Although no pathogens (flaviviruses) were detected in the analysed mosquito specimens, chicken blood serum analyses recorded a 1.7% WNV antibody detection rate in the 2018 samples. Notably detection of the first WNV positive chicken preceded human WNV occurrence in the same region by approximately two weeks. The chitin synthase mutation I1043F (associated with high diflubenzuron resistance) was recorded at an 8% allelic frequency in Lasithi prefecture Cx. pipiens mosquitoes (sampled in 2020) for the first time in Greece. Markedly, Cx. pipiens populations in all four prefectures were found harboring the kdr mutations L1014F/C/S (associated with pyrethroid resistance) at a close to fixation rate, with mutation L1014C being the most commonly found allele (≥74% representation). Voltage gated sodium channel analyses in Ae. albopictus revealed the presence of the kdr mutations F1534C and I1532T (associated with putative mild pyrethroid resistance phenotypes) yet absence of V1016G. Allele F1534C was recorded in all prefectures (at an allelic frequency range of 25–46.6%) while I1532T was detected in populations from Chania, Rethymnon and Heraklion (at frequencies below 7.1%). Finally, no kdr mutations were detected in the Anopheles specimens included in the analyses.Conclusions/SignificanceThe findings of our study are of major concern for VBD control in Crete, highlighting (i) the necessity for establishing seasonal integrated entomological/pathogen surveillance programs, supporting the design of targeted vector control responses and; ii) the need for establishing appropriate insecticide resistance management programs ensuring the efficacy and sustainable use of DFB and pyrethroid based products in vector control.     

Local sequential minimization of double stranded B-DNA using Monte Carlo annealing

A software algorithm has been developed to investigate the folding process in B-DNA structures in vacuum under a simple and accurate force field. This algorithm models linear double stranded B-DNA sequences based on a local, sequential minimization procedure. The original B-DNA structures were modeled using initial nucleotide structures taken from the Brookhaven database. The models contain information at the atomic level allowing one to investigate as accurately as possible the structure and characteristics of the resulting DNA structures. A variety of DNA sequences and sizes were investigated containing coding and non-coding, random and real, homogeneous or heterogeneous sequences in the range of 2 to 40 base pairs. The force field contains terms such as angle bend, Lennard-Jones, electrostatic interactions and hydrogen bonding which are set up using the Dreiding II force field and defined to account for the helical parameters such as twist, tilt and rise. A close comparison was made between this local minimization algorithm and a global one (previously published) in order to find out advantages and disadvantages of the different methods. From the comparison, this algorithm gives better and faster results than the previous method, allowing one to minimize larger DNA segments. DNA segments with a length of 40 bases need approximately 4 h, while 2.5 weeks are needed with the previous method. After each minimization the angles between phosphate–oxygen-carbon A₁, the oxygen–phosphate–oxygen A₂ and the average helical twists were calculated. From the generated fragments it was found that the bond angles are A₁=150°±2°and A₂=130°±10°, while the helical twist is 36.6°±2° in the A strand and A₁=150°±6° and A₂=130±6° with helical twist 39.6°±2° in the B strand for the DNA segment with the same sequence as the Dickerson dodecamer.Figure The final minimized DNA segment of the Dickerson dodecamer sequence represented by ball drawings and viewed (left) perpendicular and (right) down the helical axis     

A reliable lacZ expression reporter cassette for multipurpose, knockout-first alleles

Alteration of the mouse genome through homologous recombination in embryonic stem (ES) cells is the most accurate and versatile way to dissect gene function in a vertebrate model. Most often, a selectable marker is used to create a knockout allele by replacing an essential part of the gene. However, knockout strategies are limited because the mutation is present constitutively. Conditional approaches based on the Cre-loxP site-specific recombination (SSR) system address this limitation; however, it requires that all parts of the targeted gene remain in ES cells. Here we report success with a "knockout-first" strategy that ablates gene function by insertion of RNA processing signals without deletion of any of the target gene. Incorporation of site-specific recombination target sites creates a multipurpose allele for both knockout and conditional applications.     

CC chemokine receptor 9 expression defines a subset of peripheral blood lymphocytes with mucosal T cell phenotype and Th1 or T-regulatory 1 cytokine profile

The chemokine receptor CCR9 is expressed on most small intestinal lamina propria and intraepithelial lymphocytes and on a small subset of peripheral blood lymphocytes. CCR9-expressing lymphocytes may play an important role in small bowel immunity and inflammation. We studied the phenotype and functional characteristics of CCR9(+) lymphocytes in blood from normal donors. A subset of CCR9(+) T cells have a phenotype of activated cells and constitutively express the costimulatory molecules CD40L and OX-40. In contrast to CCR9(-), CCR9(+)CD4(+) peripheral blood T cells proliferate to anti-CD3 or anti-CD2 stimulation and produce high levels of IFN-gamma and IL-10. IL-10-producing cells were exclusively detected within the CCR9(+) subset of CD4(+) T cells by intracellular staining and were distinct from IL-2- and IFN-gamma-producing cells. Moreover, memory CCR9(+)CD4(+) lymphocytes respond to CD2 stimulation with proliferation and IFN-gamma/IL-10 production, whereas memory CCR9(-)CD4(+) cells were unresponsive. In addition, memory CCR9(+)CD4(+) T cells support Ig production by cocultured CD19(+) B cells in the absence of prior T cell activation or addition of exogenous cytokines. Our data show that the memory subset of circulating CCR9(+)CD4(+) T cells has characteristics of mucosal T lymphocytes and contains cells with either Th1 or T-regulatory 1 cytokine profiles. Studies on the cytokine profile and Ag specificity of this cell subset could provide important insight into small intestinal immune-mediated diseases and oral tolerance in humans.     

Fibroblast-specific expression of a kinase-deficient type II transforming growth factor beta (TGFbeta) receptor leads to paradoxical activation of TGFbeta signaling pathways with fibrosis in transgenic mice

To better understand the role of disrupted transforming growth factor beta (TGFbeta) signaling in fibrosis, we have selectively expressed a kinase-deficient human type II TGFbeta receptor (TbetaRIIDeltak) in fibroblasts of transgenic mice, using a lineage-specific expression cassette subcloned from the pro-alpha2(I) collagen gene. Surprisingly, despite previous studies that characterized TbetaRIIDeltak as a dominant negative inhibitor of TGFbeta signaling, adult mice expressing this construct demonstrated TGFbeta overactivity and developed dermal and pulmonary fibrosis. Compared with wild type cells, transgenic fibroblasts proliferated more rapidly, produced more extracellular matrix, and showed increased expression of key markers of TGFbeta activation, including plasminogen activator inhibitor-1, connective tissue growth factor, Smad3, Smad4, and Smad7. Smad2/3 phosphorylation was increased in transgenic fibroblasts. Overall, the gene expression profile of explanted transgenic fibroblasts using cDNA microarrays was very similar to that of littermate wild type cells treated with recombinant TGFbeta1. Despite basal up-regulation of TGFbeta signaling pathways, transgenic fibroblasts were relatively refractory to further stimulation with TGFbeta1. Thus, responsiveness of endogenous genes to TGFbeta was reduced, and TGFbeta-regulated promoter-reporter constructs transiently transfected into transgenic fibroblasts showed little activation by recombinant TGFbeta1. Responsiveness was partially restored by overexpression of wild type type II TGFbeta receptors. Activation of MAPK pathways by recombinant TGFbeta1 appeared to be less perturbed than Smad-dependent signaling. Our results show that expression of TbetaRIIDeltak selectively in fibroblasts leads to paradoxical ligand-dependent activation of downstream signaling pathways and causes skin and lung fibrosis. As well as confirming the potential for nonsignaling receptors to regulate TGFbeta activity, these findings support a direct role for perturbed TGFbeta signaling in fibrosis and provide a novel genetically determined animal model of fibrotic disease.     

Single molecule characterization of P-selectin/ligand binding

P-selectin expressed on activated platelets and vascular endothelium mediates adhesive interactions to polymorphonuclear leukocytes (PMNs) and colon carcinomas critical to the processes of inflammation and blood-borne metastasis, respectively. How the overall adhesiveness (i.e. the avidity) of receptor/ligand interactions is controlled by the affinity of the individual receptors to single ligands is not well understood. Using single molecule force spectroscopy, we probed in situ both the tensile strength and off-rate of single P-selectin molecules binding to single ligands on intact human PMNs and metastatic colon carcinomas and compared them to the overall avidity of these cells for P-selectin substrates. The use of intact cells rather than purified proteins ensures the proper orientation and preserves post-translational modifications of the P-selectin ligands. The P-selectin/PSGL-1 interaction on PMNs was able to withstand forces up to 175 pN and had an unstressed off-rate of 0.20 s(-1). The tensile strength of P-selectin binding to a novel O-linked, sialylated protease-sensitive ligand on LS174T colon carcinomas approached 125 pN, whereas the unstressed off-rate was 2.78 s(-1). Monte Carlo simulations of receptor/ligand bond rupture under constant loading rate for both P-selectin/PSGL-1 and P-selectin/LS174T ligand binding give distributions and mean rupture forces that are in accord with experimental data. The pronounced differences in the affinity for P-selectin/ligand binding provide a mechanistic basis for the differential abilities of PMNs and carcinomas to roll on P-selectin substrates under blood flow conditions and underline the requirement for single molecule affinity measurements.     

Saccharomyces cerevisiae RAD5 influences the excision repair of DNA minor groove adducts

Nucleotide excision repair (NER) is the primary pathway for the removal of DNA adducts that distort the double helix. In the yeast Saccharomyces cerevisiae the RAD6 epistasis group defines a more poorly characterized set of DNA damage response pathways, believed to be distinct from NER. Here we show that the elimination of the DNA minor groove adducts formed by an important class of anticancer antibiotic (CC-1065 family) requires NER factors in S. cerevisiae. We also demonstrate that the elimination of this class of minor groove adduct from the active MFA2 gene depends upon functional Rad18 and Rad6. This is most clear for the repair of adducts on the transcribed strand, where an absolute requirement for Rad6 and Rad18 was seen. Further experiments revealed that a specific RAD6-RAD18-controlled subpathway, the RAD5 branch, mediates these events. Cells disrupted for rad5 are highly sensitive to this minor groove binding agent, and rad5 cells exhibit an in vivo adduct elimination defect indistinguishable from that seen in rad6 and rad18 cells as well as in NER-defective cells. Our results indicate that the RAD5 subpathway may interact with NER factors during the repair of certain DNA adducts.