N4-hydroxycytosine dioxolane nucleosides and their activity against hepatitis B virus

Novel racemic, D- and L-beta-dioxolane N4-hydroxycytosine nucleosides have been synthesized and evaluated for their activity against hepatitis B virus. None of the synthesized nucleosides demonstrated selective anti-HBV activity.     

How can nematodes mate without spicules? Function of the male gonoduct glands in the roundworm Myolaimus

Males of roundworms (Nematoda) usually possess cuticular copulatory organs (spicules) that are inserted in the female's vulva to attach the male to the female and to widen the vulva against the inner body pressure for sperm transfer. Among free-living nematodes, the only exception of this rule is Myolaimus where the males lack spicules. Until now there exist no reports on how mating is achieved in Myolaimus. Here we show that sperm transfer in Myolaimus apparently involves at least six different secretions of the male gonoduct that are pumped into a sack-like cuticular protrusion of the female's vulva to form a spermatophore-like capsule. The role of gonoduct glands in male nematodes (even in the model organism Caenorhabditis elegans) is poorly understood. Here we present the first study explaining the role of different vas deferens gland products in nematodes and argue that Myolaimus males lost their spicules as a result of sperm competition.     

Prostate-specific antigen immunosensing based on mixed self-assembled monolayers, camel antibodies and colloidal gold enhanced sandwich assays

Prostate-specific antigen (PSA) is a valuable biomarker for prostate cancer screening. We developed a PSA immunoassay on a commercially available surface plasmon resonance biosensor. Our PSA receptor molecule consists of a single domain antigen-binding fragment, cAbPSA-N7, derived from dromedary heavy-chain antibodies and identified after phage display. It binds PSA with a high k(on) value of 1.9x10(6) M-1 s-1, and was covalently immobilised on a gold substrate via a mixed self-assembled monolayer (SAM) of alkanethiols by using carbodiimide-coupling chemistry in 10mM acetate buffer pH 5.5 to obtain an optimal pre-concentration. The best performing and optimised mixed SAM consisted of (10%) 16-mercapto-1-hexadecanoic acid (16-MHA) for covalent cAbPSA-N7 immobilisation and (90%) 11-mercapto-1-undecanol (11-MUOH) to minimise non-specific adsorption of the analyte. In this way, two advantages are incorporated in a single coupling layer. Up to 28 fmol/mm2 of cAbPSA-N7 could be immobilised and 30% of its binding sites participate actively in PSA interaction. In addition, the optimised layer showed also optimal performance to assess physiological samples. Although PSA concentrations as low as 10 ng/ml could be detected directly, this detection limit could be enhanced to PSA levels in the sub ng/ml range by introducing a sandwich assay involving a biotinylated secondary antibody and streptavidin modified gold nanoparticles. This approach realizes the PSA detection at clinical relevant concentrations.     

Assessment of the genetic diversity among arcobacters isolated from poultry products by using two PCR-based typing methods

In this study, enterobacterial repetitive intergenic consensus PCR (ERIC-PCR) and randomly amplified polymorphic DNA PCR (RAPD-PCR) were optimized for characterization of Arcobacter butzleri, Arcobacter cryaerophilus, and Arcobacter skirrowii. In addition, a simple and rapid DNA extraction method was tested for use in both typing procedures. Both methods had satisfactory typeability and discriminatory power, but the fingerprints generated with ERIC-PCR were more reproducible and complex than those obtained with RAPD-PCR. The use of nondiluted boiled cell suspensions as DNA templates was found to be very useful in ERIC-PCR. Characterization of large numbers of Arcobacter isolates is therefore preferably performed by the ERIC-PCR procedure. Isolates for which almost identical ERIC fingerprints are generated may subsequently be characterized by RAPD-PCR, although adjustment and standardization of the amount of the DNA template are necessary. In the second part of this study, the genotypic diversity of arcobacters present on broiler carcasses was assessed by using both typing methods. A total of 228 cultures from 24 samples were examined after direct isolation and enrichment. The isolates were identified by using a multiplex PCR as A. butzleri (n = 182) and A. cryaerophilus (n = 46). A total of 131 types (91 A. butzleri types and 40 A. cryaerophilus types) were discerned without discordance between the two typing techniques. The analysis of the poultry isolates showed that poultry products may harbor not only more than one species but also multiple genotypes. All genotypes were confined to one poultry sample, and only three genotypes were found after simultaneous enrichment and direct isolation. These results demonstrate that different outcomes can be obtained in epidemiological studies depending on the isolation procedure used and the number of isolates characterized.     

Droplet digital PCR is an accurate method to assess methylation status on FFPE samples

Most tissue samples available for cancer research are archived as formalin-fixed paraffin-embedded (FFPE) samples. However, the fixation process and the long storage duration lead to DNA fragmentation and hinder epigenome analysis. The use of droplet digital PCR (ddPCR) to detect DNA methylation has recently emerged. In this study, we compare an optimized ddPCR assay with a conventional qPCR assay by targeting a dilution series of control DNA. In addition, we compare the ddPCR technology with results from Infinium arrays targeting two separate CpG sites on a set of colon adenoma FFPE samples. Our data demonstrate that qPCR and ddPCR assess methylation status equally well on dilution controls with a high DNA input. However, the methylation detection on low-input samples is more accurate using ddPCR. The proposed primer design (methylation-independent primers with amplification of solely the converted DNA target) will allow for methylation detection, independent of bisulfite conversion efficiency. Those data show that ddPCR can be used for methylation analysis on FFPE samples with a wide range of DNA input and that the precision of the assay depends largely on the total amount of amplifiable DNA fragments. Due to accessibility of the ddPCR technology and its accuracy on high- as well as low-DNA input samples, we propose the use of this approach for studies involving degraded FFPE samples.     

Use of Antibody Responses against Locus of Enterocyte Effacement (LEE)-Encoded Antigens To Monitor Enterohemorrhagic Escherichia coli Infections on Cattle Farms

Enterohemorrhagic Escherichia coli (EHEC) is a significant zoonotic pathogen causing severe disease associated with watery and bloody diarrhea, hemorrhagic colitis, and the hemolytic-uremic syndrome (HUS) in humans. Infections are frequently associated with contact with EHEC-contaminated ruminant feces. Both natural and experimental infection of cattle induces serum antibodies against the LEE-encoded proteins intimin, EspA, EspB, and Tir and the Shiga toxins Stx1 and Stx2, although the latter are poorly immunogenic in cattle. We determined whether antibodies and/or the kinetics of antibody responses against intimin, Tir, EspA, and/or EspB can be used for monitoring EHEC infections in beef cattle herds in order to reduce carcass contamination at slaughter. We examined the presence of serum antibodies against recombinant O157:H7 E. coli intimin EspA, EspB, and Tir during a cross-sectional study on 12 cattle farms and during a longitudinal time course study on two EHEC-positive cattle farms. We searched for a possible correlation between intimin, Tir, EspA, and/or EspB antibodies and fecal excretion of EHEC O157, O145, O111, O103, or O26 seropathotypes. The results indicated that serum antibody responses to EspB and EspA might be useful for first-line screening at the herd level for EHEC O157, O26, and most likely also for EHEC O103 infections. However, antibody responses against EspB are of less use for monitoring individual animals, since some EHEC-shedding animals did not show antibody responses and since serum antibody responses against EspB could persist for several months even when shedding had ceased.     

Design and synthesis of HIV-1 protease inhibitors for a long-acting injectable drug application

The design and synthesis of novel HIV-1 protease inhibitors (PIs) (1–22), which display high potency against HIV-1 wild-type and multi-PI-resistant HIV-mutant clinical isolates, is described. Lead optimization was initiated from compound 1, a Phe–Phe hydroxyethylene peptidomimetic PI, and was directed towards the discovery of new PIs suitable for a long-acting (LA) injectable drug application. Introducing a heterocyclic 6-methoxy-3-pyridinyl or a 6-(dimethylamino)-3-pyridinyl moiety (R³) at the para-position of the P1′ benzyl fragment generated compounds with antiviral potency in the low single digit nanomolar range. Halogenation or alkylation of the metabolic hot spots on the various aromatic rings resulted in PIs with high stability against degradation in human liver microsomes and low plasma clearance in rats. Replacing the chromanolamine moiety (R¹) in the P2 protease binding site by a cyclopentanolamine or a cyclohexanolamine derivative provided a series of high clearance PIs (16–22) with EC₅₀s on wild-type HIV-1 in the range of 0.8–1.8 nM. PIs 18 and 22, formulated as nanosuspensions, showed gradual but sustained and complete release from the injection site over two months in rats, and were therefore identified as interesting candidates for a LA injectable drug application for treating HIV/AIDS.