Enhanced flavour formation by combination of selected lactococci from industrial and artisanal origin with focus on completion of a metabolic pathway

Combinations of lactococcal strains from various origins with divers properties were developed as new starters for new dairy products. Flavour formation by such tailor-made cultures was studied. In some cases, a strongly enhanced flavour was observed. For instance, the combination of B1157 and SK110 strains in milk resulted in a very strong chocolate-like flavour. B1157 produces only a moderate chocolate-like flavour, whereas SK110 alone fails to produce this flavour. Headspace gas chromatography results corroborate the organoleptic evaluations. High levels of branched-chain aldehydes were found when B1157 and SK110 were grown together. The enzyme activities involved in this pathway were studied; both strains contain transaminase activity. Although B1157 had a very high amino acid decarboxylating activity, its release of amino acids from milk protein was limited. SK110 was strongly limited in decarboxylating activity, although this strain is very active in proteolysis. By combining these strains, the substrates released by SK110 can directly be used by the other strain, resulting in the completion of the whole flavour-formation pathway. This opens new avenues for the preparation of tailor-made cultures.     

A new facile method for spin-labeling of oligonucleotides

A new facile method for spin-labeling suitable for DNA and RNA oligonucleotides is presented. The nitroxide 3-ethenyl-2,2,5,5-tetramethyl-pyrrolin-1-yloxy was directly introduced during automated solid-phase synthesis by a Pd(0) cross coupling reaction. The main advantages of this procedure are the small amount of spin-label needed for the derivatisation of the oligonucleotide and the high coupling efficiency on the solid phase.     

Stacking and stability of RNA duplexes containing fluorobenzene and fluorobenzimidazole nucleosides

Six different fluorobenzene or fluorobenzimidazole ribonucleosides and one abasic site were incorporated in oligoribonucleotides. Individual contributions of base stacking and solvation of the modified nucleosides could be determined. In fluorobenzene.fluorobenzimidazole-modified base pairs a duplex stabilizing force was found that points to a weak F...H hydrogen bond. The lipophilicity of the unprotected nucleosides were investigated by determination of 1-octanol water partition coefficients.     

Staphylococcus aureus alpha-toxin-induced cell death: predominant necrosis despite apoptotic caspase activation

Recent data suggest that alpha-toxin, the major hemolysin of Staphylococcus aureus, induces cell death via the classical apoptotic pathway. Here we demonstrate, however, that although zVAD-fmk or overexpression of Bcl-2 completely abrogated caspase activation and internucleosomal DNA fragmentation, they did not significantly affect alpha-toxin-induced death of Jurkat T or MCF-7 breast carcinoma cells. Caspase inhibition had also no effect on alpha-toxin-induced lactate dehydrogenase release and ATP depletion. Furthermore, whereas early assessment of apoptosis induction by CD95 resulted solely in the generation of cells positive for active caspases that were, however, not yet permeable for propidium iodide, a substantial proportion of alpha-toxin-treated cells were positive for both active caspases and PI. Finally, electron microscopy demonstrated that even in the presence of active caspases, alpha-toxin-treated cells displayed a necrotic morphology characterized by cell swelling and cytoplasmic vacuolation. Together, our data suggest that alpha-toxin-induced cell death proceeds even in the presence of activated caspases, at least partially, in a caspase-independent, necrotic-like manner.     

Drugs for the control of parasitic diseases: current status and development in schistosomiasis

The morbidity caused by schistosomiasis has been controlled in China, Egypt and the Philippines mainly by the widespread use of the safe and efficacious drug praziquantel (PZQ), and by oxamniquin and PZQ in Brazil. To date, there is no evidence of development of clinically relevant resistance. Thanks to the commitment of national governments at the World Health Assembly in 2001, and the emergence of significant funding for control, it is predicted that there will soon be more widespread use of PZQ in sub-Saharan Africa, where morbidity due to schistosomiasis is most prevalent. There are currently no available alternative drugs to PZQ (with the possible exception of oxamniquin), although perhaps PZQ analogues could be developed. Artemether, used to control malaria, is effective against immature schistosomes, but is less effective against adult worms. The efficacy of myrrh, recently marketed as an antischistosomacide in Egypt, has not been independently confirmed.     

A new concept for DNA-arrays

We will insert a cleavage site in an oligodeoxynucleotide, which can be used for a selective and quantitative cleavage. For that reason we synthesized the four 5'-S-(4,4'-dimethoxytrityl)-mercapto-2'-deoxynucleotide-3'-O-(2-cyanoethoxydiisopropylamino)-phosphites (5a-d). The cleavage of P-S and C-S bonds is described (Mag, M.; Lücking, S.; Engels, J.W. Synthesis and selective cleavage of an oligodeoxy-nucleotide containing a bridged internucleotide 5'-phosphorthioate linkage. Nucleic Acids Res. 1991, 19 (7), 1437-1441; Marriott, J.H.; Mottahedeh, M.; Reese, C.B. 9-(4-methoxyphenyl)xanthen-9-thiol: A useful reagent for the preparation of thiols. Tetrahedron Lett. 1990, 31 (51), 7485-7488; Divakar, K.J.; Mottoh, A.; Reese, C.B.; Shanghvi, Y.S. Approaches to the synthesis of 2' thio analogues of pyrimidine ribosides. J. Chem. Sc., Perkin Trans. 1 1990, 969-974). The oligodeoxynucleotides with an achiral bridged 5'-phosphorothioate linkage 5'-O-P-S-3' are synthesized by the phosphoramidite procedure.     

Evolutionary distances for protein-coding sequences: modeling site- specific residue frequencies

Estimation of evolutionary distances from coding sequences must take into account protein-level selection to avoid relative underestimation of longer evolutionary distances. Current modeling of selection via site-to-site rate heterogeneity generally neglects another aspect of selection, namely position-specific amino acid frequencies. These frequencies determine the maximum dissimilarity expected for highly diverged but functionally and structurally conserved sequences, and hence are crucial for estimating long distances. We introduce a codon- level model of coding sequence evolution in which position-specific amino acid frequencies are free parameters. In our implementation, these are estimated from an alignment using methods described previously. We use simulations to demonstrate the importance and feasibility of modeling such behavior; our model produces linear distance estimates over a wide range of distances, while several alternative models underestimate long distances relative to short distances. Site-to-site differences in rates, as well as synonymous/nonsynonymous and first/second/third-codon-position differences, arise as a natural consequence of the site-to-site differences in amino acid frequencies.      

<Emphasis Type="Italic">TRAF1/C5</Emphasis>polymorphism is not associated with increased mortality in rheumatoid arthritis: two large longitudinal studies

Introduction  

Recently an association between a genetic variation in TRAF1/C5 and mortality from sepsis or cancer was found in rheumatoid arthritis (RA). The most prevalent cause of death, cardiovascular disease, may have been missed in that study, since patients were enrolled at an advanced disease stage. Therefore, we used an inception cohort of RA patients to investigate the association between TRAF1/C5 and cardiovascular mortality, and replicate the findings on all-cause mortality. As TRAF1/C5 associated mortality may not be restricted to RA, we also studied a large cohort of non-RA patients.