Collagen-Like Proteins in Pathogenic E. coli Strains

The genome sequences of enterohaemorrhagic E. coli O157:H7 strains show multiple open-reading frames with collagen-like sequences that are absent from the common laboratory strain K-12. These putative collagens are included in prophages embedded in O157:H7 genomes. These prophages carry numerous genes related to strain virulence and have been shown to be inducible and capable of disseminating virulence factors by horizontal gene transfer. We have cloned two collagen-like proteins from E. coli O157:H7 into a laboratory strain and analysed the structure and conformation of the recombinant proteins and several of their constituting domains by a variety of spectroscopic, biophysical, and electron microscopy techniques. We show that these molecules exhibit many of the characteristics of vertebrate collagens, including trimer formation and the presence of a collagen triple helical domain. They also contain a C-terminal trimerization domain, and a trimeric α-helical coiled-coil domain with an unusual amino acid sequence almost completely lacking leucine, valine or isoleucine residues. Intriguingly, these molecules show high thermal stability, with the collagen domain being more stable than those of vertebrate fibrillar collagens, which are much longer and post-translationally modified. Under the electron microscope, collagen-like proteins from E. coli O157:H7 show a dumbbell shape, with two globular domains joined by a hinged stalk. This morphology is consistent with their likely role as trimeric phage side-tail proteins that participate in the attachment of phage particles to E. coli target cells, either directly or through assembly with other phage tail proteins. Thus, collagen-like proteins in enterohaemorrhagic E. coli genomes may have a direct role in the dissemination of virulence-related genes through infection of harmless strains by induced bacteriophages

Nitrogen Use Efficiency and Gaseous Nitrogen Losses from the Concentrated Liquid Fraction of Pig Slurries

Processed manure can be an alternative source of nutrients for untreated manure and mineral fertilizers. Mineral concentrates (MCs) are derived from reversed osmosis of the liquid fraction of separated pig slurries. The emissions of ammonia (NH3) and nitrous oxide (N2O) from different (processed) manures and fertilizers were tested in an incubation experiment and a greenhouse experiment with grass as a test crop. Dry matter yields and nitrogen (N) uptake were also determined in the greenhouse experiment. Incorporation into the soil decreased on NH3 emission but increased N2O emission for all nitrogen products (mineral fertilizer, untreated slurry, MC, and solid fraction of separated slurry). Incorporation of both MC, slurries, and mineral fertilizers increased N2O emission in the incubation experiment. The lowest apparent N recovery (ANR) in the pot experiment with grass was obtained for incorporated pig slurry (30–39%) and surface-applied MC (33–38%), while the highest ANRs were obtained for liquid ammonium nitrate (45–53%) and acidified MC (43–55%). It is concluded that MCs have a similar N fertilizer value as mineral N fertilizers if NH3 emission is reduced by incorporation or acidification

Bodembescherming bij doorgangsdepots voor baggerspecie : Verwaarloosbaar bodemrisico met een geochemische barrière

Bij het ontwateren en rijpen van nuttig toepasbare baggerspecie wordt veelvuldig gebruikt gemaakt van doorgangsdepots. Op initiatief van de waterschappen is een alternatief ontwikkeld voor de bodembescherming met behulp van een folie. Met een minerale bodembeschermingslaag kan eveneens een verwaarloosbaar bodemrisico bereikt worden. Een generieke regeling bleek vooralsnog niet haalbaar

Treponemicidal levels of amoxicillin in cerebrospinal fluid after oral administration

Seven patients in various stages of syphilis were treated by oral administration of amoxicillin (6 g daily) and probenecid (2 g daily) for 15 days. The treponemicidal level of amoxicillin was studied by a Treponema pallidum immobilization assay and found to be 0.070 micrograms/ml, as compared with 0.003 micrograms of penicillin/ml. Taking into account the WHO-recommended level of 0.018 micrograms/ml of penicillin, the minimal level of amoxicillin was estimated as 0.42 micrograms/ml. This level was obtained in serum and cerebrospinal fluid (CSF) of all patients treated with the above mentioned oral combination. It is concluded that treponemicidal levels of amoxicillin can be obtained in CSF after oral administration. The amoxicillin regimen described may be a valuable alternative to single-dose parenteral penicillin in the treatment of syphilitic patients with suspected CNS involvement, provided that reasonable compliance can be obtaine

CAPD peritonitis: a prospective randomized trial of oral versus intraperitoneal treatment with cephradine

In a prospective randomized clinical trial 84 peritonitis episodes were treated with cephradine, either orally or intraperitoneally. No difference in treatment outcome between both groups could be demonstrated. In episodes caused by susceptible micro-organisms a good response was seen in 82% in the oral and 82% in the intraperitoneal groups. These clinical findings were supported by the demonstration of adequate cephradine concentrations in serum and dialysate after oral as well as after intraperitoneal administration. Altogether cephradine was given orally or intraperitoneally in 88 episodes of peritonitis as drug of first choice. In 52 a complete cure was obtained, in 36 another antibiotic was subsequently needed as soon as bacterial susceptibility was known. No patient deteriorated appreciably during the delay between the start of cephradine and the switch to another antibiotic. Of the 36 episodes 14, caused by methicillin-resistant Staphylococcus epidermidis, responded well initially to cephradine but relapsed later. Change to another antibiotic effected a complete recovery in all 14 cases. Of the remaining 22 episodes, 14 were cured by the other antibiotic, in eight the catheter had to be removed. Aminoglycosides could be avoided except for ten of the episodes. During peritonitis CAPD was continued, in 71% of the cases on an outpatient basis. Mortality due to peritonitis was absent. We conclude that oral cephradine can be used as drug of first choice in the initial treatment of CAPD peritonitis, because a good initial response was obtained in 66 (52 + 14) i.e. 75% of 88 episodes. However, complete cure by cephradine alone was achieved in only 60%.(ABSTRACT TRUNCATED AT 250 WORDS

Bio-slurry as fertilizer : is bio-slurry from household digesters a better fertilizer than manure? : a literature review

In many developing countries manure is anaerobically digested to produce biogas. The residue of manure digestion, bio-slurry, can be used as fertilizer for crop production and aquaculture. This study compared bio-slurry and manure as fertilizers. Nutrients in bio-slurry, especially nitrogen, are more readily available then in manure, leading to a larger short term fertilisation effect. However, risks for N losses through volatilisation and leaching are large for bio-slurry than for manure during storage, handling and application. Unfortunately, most studies that compared bio-slurry and manure exhibited methodological shortcomings that hamper an adequate comparison