Deficiency of the Promyelocytic Leukemia Protein Fosters Hepatitis C-Associated Hepatocarcinogenesis in Mice

Overwhelming lines of epidemiological evidence have indicated that persistent infection with hepatitis C virus (HCV) is a major risk for the development of hepatocellular carcinoma (HCC). We have recently shown that HCV core protein mediates functional inactivation of the promyelocytic leukemia (PML) tumor suppressor pathway. However, the role of PML in HCC development yet remains unclear. To clarify the function of PML in liver carcinogenesis and HCV-associated pathogenesis we crossed PML-deficient mice with HCV transgene (HCV-Tg) expressing mice and treated the resulting animals with DEN/Phenobarbital, an established protocol for liver carcinogenesis. Seven months after treatment, livers were examined macroscopically and histologically. Genetic depletion of the tumor suppressor PML coincided with an increase in hepatocyte proliferation, resulting in development of multiple dysplastic nodules in 100% of the PML-deficient livers and of HCCs in 53%, establishing a tumor suppressive function of PML in the liver. In animals expressing the HCV-transgene in PML-deficient background, HCC development occurred even in 73%, while only 7% of their wildtype littermates developed HCC. The neoplastic nature of the tumors was confirmed by histology and expression of the HCC marker glutamine synthetase. Several pro- and antiapoptotic factors were tested for differential expression and liver carcinogenesis was associated with impaired expression of the proapoptotic molecule TRAIL in PML-deficient mice. In conclusion, this study provides first in vivo evidence that the tumor suppressor PML acts as an important barrier in liver carcinogenesis and HCV-dependent liver pathology.     

Fibrinogen-binding and platelet-aggregation activities of a Lactobacillus salivarius septicaemia isolate are mediated by a novel fibrinogen-binding protein

The marketplace for probiotic foods is burgeoning, measured in billions of euro per annum. It is imperative, however, that all bacterial strains are fully assessed for human safety. The ability to bind fibrinogen is considered a potential pathogenicity trait that can lead to platelet aggregation, serious medical complications, and in some instances, death. Here we examined strains from species frequently used as probiotics for their ability to bind human fibrinogen. Only one strain (CCUG 47825), a Lactobacillus salivarius isolate from a case of septicaemia, was found to strongly adhere to fibrinogen. Furthermore, this strain was found to aggregate human platelets at a level comparable to the human pathogen Staphylococcus aureus. By sequencing the genome of CCUG 47825, we were able to identify candidate genes responsible for fibrinogen binding. Complementing the genetic analysis with traditional molecular microbiological techniques enabled the identification of the novel fibrinogen receptor, CCUG_2371. Although only strain CCUG 47825 bound fibrinogen under laboratory conditions, homologues of the novel fibrinogen binding gene CCUG_2371 are widespread among L. salivarius strains, maintaining their potential to bind fibrinogen if expressed. We highlight the fact that without a full genetic analysis of strains for human consumption, potential pathogenicity traits may go undetected.     

cDNA cloning and developmental expression of pea nodulin genes

A cDNA library prepared from pea nodule poly(A)⁺ RNA was screened by differential hybridization with cDNA probes synthesized from root and nodule RNA respectively. From the cDNA clones that hybridized exclusively with the nodule probe five clones, designated pPsNod 6, 10, 11, 13 and 14 and each containing unique sequences, were further characterized together with one leghemoglobin and one root-specific cDNA clone. In vitro translation of RNA selected by the pPsNod clones showed that the corresponding genes encode nodulins with molecular weights ranging from 5 800 to 19 000. During pea root nodule development expression of the five PsNod genes starts more or less concomitantly with the onset of nitrogen fixing activity in the nodules and the time course of appearance and accumulation of the nodulin mRNAs is similar to that of leghemoglobin mRNA. In ineffective pea root nodules expression of the PsNod genes is induced but the final accumulation levels of the mRNAs are markedly reduced to various degrees. The expression of another nodulin gene, designated ENOD2, was followed using a heterologous soybean cDNA clone as probe. In pea root nodules the ENOD2 gene is expressed at least five days before the PsNod and leghemoglobin genes, and in contrast to the PsNod mRNAs the concentration of the ENOD2 mRNA is the same in wild type and fix ^- nodules. The results described suggest that in root nodules several regulatory mechanisms exist which determine the final nodulin mRNA amounts accumulating in the root nodule.     

Eradication of Helicobacter pylori Using One-week Triple Therapies Combining Omeprazole with Two Antimicrobials: The MACH I Study

Background. Eradication of Helicobacter pylori provides potential cure in the majority of patients with peptic ulcer disease, and eradication rates of more than 90% have been reported, using omeprazole in combination with two antimicrobials. The choice of antimicrobials, dose regimen and duration of treatment have varied between studies, however, and an optimal treatment still has to be established.
Materials and Methods. We conducted an international, randomized, double-blind, placebo-controlled study involving more than 100 patients in each of six treatment groups in 43 hospital gastrointestinal units in Canada, Germany, Ireland, Sweden, and the United Kingdom. Patients (n=787) with proved duodenal ulcer disease were randomized to treatment twice daily for 1 week with omeprazole, 20 mg (O), plus either placebo (P) or combinations of two of the following anti-microbials: amoxicillin, 1 gm (A), clarithromycin, 250 or 500 mg (C250, C500), or metronidazole, 400 mg (M). Eradication of H. pylori was evaluated by ¹³C-UBT, performed before and 4 weeks after treatment cessation.
Results. The eradication rates for the all-patients-treated analysis were 96%. OAC500; 95%, OMC250; 90%, OMC500; 84%, OAC250; 79%, OAM; and 1%, OP. OAC500 and OMC250 achieved eradication rates with lower 95% confidence interval limits exceeding 90%. All regimens were well-tolerated, 96% of patients complied with their dose regimen, and 2.3% of the patients discontinued treatment owing to adverse events.
Conclusions. Omeprazole triple therapies given twice daily for 1 week produce high eradication rates, are well-tolerated, and are associated with high patient compliance. The two most effective therapies were those combining omeprazole, 20 mg, with either amoxicillin, 1 gm, plus clarithromycin, 500 mg, or metronidazole, 400 mg, plus clarithromycin, 250 mg, all given twice daily.     

Review: Biosafety of E. coli β-glucuronidase (GUS) in plants

The -glucuronidase (GUS) gene is to date the most frequently used reporter gene in plants. Marketing of crops containing this gene requires prior evaluation of their biosafety. To aid such evaluations of the GUS gene, irrespective of the plant into which the gene has been introduced, the ecological and toxicological aspects of the gene and gene product have been examined. GUS activity is found in many bacterial species, is common in all tissues of vertebrates and is also present in organisms of various invertebrate taxa. The transgenic GUS originates from the enterobacterial species Escherichia coli that is widespread in the vertebrate intestine, and in soil and water ecosystems. Any GUS activity added to the ecosystem through genetically modified plants will be of no or minor influence. Selective advantages to genetically modified plants that posses and express the E. coli GUS transgene are unlikely. No increase of weediness of E. coli GUS expressing crop plants, or wild relatives that might have received the transgene through outcrossing, is expected. Since E. coli GUS naturally occurs ubiquitously in the digestive tract of consumers, its presence in food and feed from genetically modified plants is unlikely to cause any harm. E. coli GUS in genetically modified plants and their products can be regarded as safe for the environment and consumers     

A transgene-centered approach to the biosafety of transgenic phosphinothricin-tolerant plants

The microbial bar and pat genes confer tolerance to the non-selective herbicide phosphinothricin (PPT; sold as Basta or Finale). This tolerance in plants could provide an environmental gain compared to current-day herbicide cocktails, but the safety of such a transgene approach is questioned by many. The biosafety of the presence of these herbicide tolerance genes in plants is evaluated in a transgene-centered approach. Potentially, the introduction of transgenic PPT-tolerant crops could result in acquired PPT tolerance in weedy relatives of these crops. Assuming responsible use of this trait in agronomy, the ecological consequences with respect to weediness or spread of the transgenic PPT tolerance are concluded to be negligible. The key issue for the toxicological evaluation is whether or not the plant has actually been sprayed with PPT. Consumption of the gene and/or gene product from unsprayed transgenic plant material will not have adverse effects. In case of PPT-sprayed material, PPT or its derivatives could be present in food and feed and crop-specific metabolites might be formed. To date, the toxicological impact of such a putative exposure is not sufficiently clear, and further premarket testing is recommended.     

Attenuation of cell cycle regulator p27<Superscript>Kip1</Superscript> expression in vertebrate epithelial cells mediated by extracellular signals in vivo and in vitro

Cell cycle arrest in potentially dividing cells is often mediated by inhibitors of G1/S-phase cyclin-dependent kinases. The cyclin E/CDK2-inhibitor p27^Kip1 has been implicated in this context in epithelial cells. We cloned and sequenced p27^Kip1 of ducklings (Anas platyrhynchos) and used an in vitro assay system to study the mechanism of p27^Kip1 downregulation in the nasal gland which precedes an increase in proliferation rate upon initial exposure of the animals to osmotic stress. Western blot studies revealed that p27^Kip1 is downregulated during 24 h of osmotic stress in ducklings with the steepest decline in protein levels between 5 and 8 h. As indicated by the results of Northern blot and semi-quantitative PCR studies, protein downregulation is not accompanied by similar changes in mRNA levels indicating that Kip1 is regulated mainly at the translational (synthesis) or posttranslational level (degradation). Using recombinant duck Kip1 protein expressed in E. coli, we showed that Kip1 is subject to polyubiquitinylation by cytosolic enzymes from nasal gland cells indicating that loss of Kip1 may be regulated, at least in part, by acceleration of protein degradation. In cultured nasal gland tissue, attenuation of Kip1 expression could be induced by activation of the muscarinic acetylcholine receptor indicating that mAChR-receptor signalling may play a role in the re-entry of quiescent gland cells into the cell cycle.     

Local coexpression domains of two to four genes in the genome of Arabidopsis

Expression of genes in eukaryotic genomes is known to cluster, but cluster size is generally loosely defined and highly variable. We have here taken a very strict definition of cluster as sets of physically adjacent genes that are highly coexpressed and form so-called local coexpression domains. The Arabidopsis (Arabidopsis thaliana) genome was analyzed for the presence of such local coexpression domains to elucidate its functional characteristics. We used expression data sets that cover different experimental conditions, organs, tissues, and cells from the Massively Parallel Signature Sequencing repository and microarray data (Affymetrix) from a detailed root analysis. With these expression data, we identified 689 and 1,481 local coexpression domains, respectively, consisting of two to four genes with a pairwise Pearson's correlation coefficient larger than 0.7. This number is approximately 1- to 5-fold higher than the numbers expected by chance. A small (5%-10%) yet significant fraction of genes in the Arabidopsis genome is therefore organized into local coexpression domains. These local coexpression domains were distributed over the genome. Genes in such local domains were for the major part not categorized in the same functional category (GOslim). Neither tandemly duplicated genes nor shared promoter sequence nor gene distance explained the occurrence of coexpression of genes in such chromosomal domains. This indicates that other parameters in genes or gene positions are important to establish coexpression in local domains of Arabidopsis chromosomes.     

The release of genetically modified crops into the environment. Part II. Overview of ecological risk assessment

Despite numerous future promises, there is a multitude of concerns about the impact of GM crops on the environment. Key issues in the environmental assessment of GM crops are putative invasiveness, vertical or horizontal gene flow, other ecological impacts, effects on biodiversity and the impact of presence of GM material in other products. These are all highly interdisciplinary and complex issues. A crucial component for a proper assessment is defining the appropriate baseline for comparison and decision. For GM crops, the best and most appropriately defined reference point is the impact of plants developed by traditional breeding. The latter is an integral and accepted part of agriculture. In many instances, the putative impacts identified for GM crops are very similar to the impacts of new cultivars derived from traditional breeding. When assessing GM crops relative to existing cultivars, the increased knowledge base underpinning the development of GM crops will provide greater confidence in the assurances plant science can give on the risks of releasing such crops.