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M Tromp

Publications and source records attributed to M Tromp.

9 recordsLinked to original sources
PubMed2000

Complement-resistant Moraxella catarrhalis forms a genetically distinct lineage within the species.

Moraxella catarrhalis is a bacterial species that has been implicated in 15-20% of all cases of otitis media in the USA and the complement-resistant variant of M. catarrhalis has been considered particularly pathogenic. A collection of geographically diverse, complement-sensitive (n=28) and -resistant strains (n=47) of M. catarrhalis was assembled in order to analyse the bacterial population structure. All strains were identified as M. catarrhalis by conventional microbiological and biochemical methods. Amplification of the small subunit (ssu) ribosomal RNA gene followed by restriction fragment length polymorphism (RFLP) analysis did not reveal consistent differences between serum-susceptible and -resistant M. catarrhalis isolates. Interestingly, upon automated ribotyping using the Qualicon RiboPrinter(R) microbial characterisation system, the complement-sensitive and -resistant strains segregated into two groups. This suggested the existence of two clearly distinguishable lineages within the species M. catarrhalis. This observation was corroborated by pulsed field gel electrophoresis (PFGE) of DNA macro-restriction fragments, a non-ribosomal PCR RFLP procedure and random amplification of polymorphic DNA (RAPD) analysis. All procedures grouped the two variants similarly. Redefinition of the taxonomic status of complement-resistant M. catarrhalis or even the definition of a new species may be opportune.

Bacterial Typing Techniques↗
PubMed2000

Pre-clinical pharmacological profile of the novel glycoconjugate Org 36764 with both factor Xa and thrombin (IIa) inhibitory activities.

Org 36764, is an antithrombin III (AT) and thrombin binding carbohydrate, which accelerates the inactivation of both factor Xa and thrombin by AT. It displays in buffer an anti-Xa and anti-thrombin activity of 415 and 2 U/mg, respectively, compared to 172 and 114 U/mg, respectively, for unfractionated heparin (UFH), Org 36764 does not cross-react with HIT (heparin induced thrombocytopenia) antibodies and is not neutralised by PF4. In experimental models in rats, on a molar basis. Org 36764 was more active than the pentasaccharide SanOrg 34006 (= AT binding domain of Org 36764) in arterial thrombosis, but both were equally active in venous thrombosis. In arterial thrombosis following endothelial damage by ferric chloride, Org 36764 was more active than the LMW heparin enoxaparin and SanOrg 34006 and similar active to UFH. At AT saturating doses the bleeding enhancement was not more than 3.5 times the control value. Org 36764 was more active in suppressing in vivo thrombus formation on stents than UFH. SanOrg 34006 or a combination of ticlopidine and aspirin. The results indicate that the novel drug Org 36764 is a drug with antithrombotic potential against venous and arterial thrombosis.

Animals↗
PubMed1991

Reactivation of vanadium bromoperoxidase; inhibition by metallofluoric compounds.

The effect of phosphate analogs (pyrophosphate, aluminofluoride and beryllofluoride complexes) on the reactivation of apobromoperoxidase by vanadate was studied. P2O7(4-) inhibited the reactivation in the millimolar range. Of the different aluminofluoride complexes, only AlF4- was inhibitory. In addition, BeF4(2-) also appeared to bind with high affinity to the apobromoperoxidase, thus inhibiting the reactivation very strongly. The inhibition observed supports a mechanism in which the fluorometallic complexes act as analogs of vanadate and bind accordingly to the apobromoperoxidase.

Aluminum↗
PubMed1986

Synthesis of nucleic acid methylphosphonates via the 1-hydroxybenzotriazole phosphotriester approach.

Dinucleoside methylphosphonates can easily be prepared starting from properly protected d-nucleosides and the bifunctional phosphorylating reagent methyl-O,O-bis(1-benzotriazolyl)phosphate. Separation of the diastereoisomers of 5'-DMTR-d-Ap(Me)T-3'-lev affords optically pure dinucleoside methylphosphonates which, after removal of the 3'-levulinoyl group, have been used for the synthesis of the two optically pure diastereoisomers of the hexamer d-CpGpAp(Me)TpCpG. Further, a one-pot procedure for the preparation of uridine-3',5'-cyclic methylphosphonate will be described. We also found that 3',5'-methylphosphonate linkages in RNA are not stable towards mild acid treatment.

Chemical Phenomena↗
PubMed1985

Adenovirus DNA replication in vitro: site-directed mutagenesis of the nuclear factor I binding site of the Ad2 origin.

The template requirements for efficient adenovirus DNA replication were studied in vitro in a reconstituted system with cloned DNA fragments, containing the Ad2 origin region, as templates. Replication is enhanced by nuclear factor I, a cellular protein that binds specifically to the Ad2 origin. This stimulation is shown to be strongly dependent on the concentration of the adenovirus DNA binding protein. Using synthetic oligonucleotides we have constructed plasmids with base substitutions in the nuclear factor I binding region. Footprint analysis and competition filter binding studies show that two of the three small blocks of conserved nucleotides in this region are involved in the binding of nuclear factor I. The binding affinity can be influenced by the base composition of the degenerate region just outside these two blocks. In vitro initiation and DNA chain elongation experiments with the mutants demonstrate that binding of nuclear factor I to the Ad2 origin is necessary for stimulation. However, binding alone is not always sufficient since a mutation which only slightly disturbs binding is strongly impaired in stimulation of DNA replication by nuclear factor I.

Adenoviridae↗
PubMed1985

Virus-induced synthesis of messenger RNAs for precursors of pathogenesis-related proteins in tobacco.

Infection of Samsun NN tobacco with tobacco mosaic virus (TMV) induces a number of host-encoded, so-called pathogenesis-related (PR-) proteins, which are found in the intercellular space of the leaf and are associated with induced resistance. By immunoprecipitation of their in vitro translation products we were able to detect the mRNAs corresponding to a number of PR-proteins in TMV-infected tobacco, but not in healthy plants. Analysis by the Northern blot technique using cloned cDNA of PR1-mRNAs as probe showed that the mRNAs for the closely related proteins PR1a, 1b and 1c occur at a low level in healthy tobacco; upon TMV infection this level is increased > 100-fold. The PR1-specific probe did no hybridize to mRNAs corresponding to other PR-proteins. Sequencing of the 5'-terminal region of PR1-mRNAs showed that PR1-proteins are derived from precursors by removal of an N-terminal signal peptide of 30 amino acids.

Amino Acid Sequence↗
PubMed1984

Polymer supported DNA synthesis using hydroxybenzotriazole activated phosphotriester intermediates.

Phosphorylation of N-acyl-5'-O-DMTr-d-nucleosides, or similarly protected DNA-dimers having a free 3'-OH group, with 2-chlorophenyl-0,0-bis(1-benzotriazolyl)phosphate affords reactive 3'-phosphotriester derivatives. The latter intermediates can be used, without further purification, for the synthesis of DNA-fragments on the controlled pore glass/long chain alkylamine support. Further, 2-cyano-1,1-dimethylethoxy dichlorophosphine proved to be very suitable for the preparation of 5'-phosphorylated DNA-fragments on the same type of solid support.

Chromatography, High Pressure Liquid↗