Cloning, sequencing and distribution of the Salmonella typhimurlum LT2 siaiidase gene, nanH, provides evidence for interspecies gene transfer

The Salmonella typhimurium LT2 sialidase (neuraminidase, EC 3.2.1.18) structural gene, nanH, has been cloned and sialidase overproduced from multicopy plasmids in Escherichia coli. Sialidase expression was regulated positively by cAMP. In contrast, certain Tn1000 insertions located upstream of nanH coding sequences reduced sialidase activity. A nanH chromosomal insertion mutation constructed by marker exchange demonstrated a single sialidase gene copy in S. typhimurium LT2. The complete nucleotide sequence of nanH, encoding a 41,300 dalton polypeptide, was determined and the derived primary structure was similar to sialidases from Clostridium perfringens, Clostridium sordellii, Bacteroides fragilis, and Trypanosoma cruzi. Comparative sequence analysis, including codon usage and secondary structure predictions, indicated that the S. typhimurium and clostridial sialidases are homologous, strongly suggestive of an interspecies gene transfer event. At least two primary sequence motifs of the bacterial enzymes were detected in influenza A virus sialidases. The predicted secondary structure of the bacterial enzymes was strikingly similar to viral sialidase. From the population distribution of nanH detected within a collection of salmonellae, it was apparent that S. typhimurium obtained its nanH copy most recently from Salmonella arizonae. S. typhimurium LT2 is thus a genetic mosaic that differs from other strains of even the same serotype by nanH plus potentially additional characters linked to nanH. These results have relevance to the evolution and function of sialidases in pathogenic microbes, and to the origin of the sialic acids.     

Enzymatic characterization of oral and non-oral black-pigmented Bacteroides species

The purpose of this study was to investigate the production of various enzymes by oral and non-oral black-pigmented Bacteroides species using chromogenic substrates. The 19 substrates present in the API ZYM system did not differentiate between B. melaninogenicus, B. denticola, B. loescheii and B. levii. The asaccharolytic black-pigmented Bacteroides species showed each species specific enzyme activity, however, differences were based on one enzyme only as far as B. asaccharolyticus and B. endodontalis are concerned. An extended number of 40 chromogenic substrates were tested in order to find more species specific enzyme. With a set of 20 substrates it appeared to be possible to discriminate between all species tested. The possibility to use enzymes for the identification of black-pigmented Bacteroides is discussed.     

Proteolytic activity of black-pigmented Bacteroides strains

Abstract The proteolytic activity of several black-pigmented Bacteroides species was measured. Bacteroides gingivalis was the only species having collagenolytic activity. General proteolytic activity on gelatin and Azocoll was shown in cultures of B. gingivalis, B. asaccharolyticus, B. endodontalis, B. intermedius, B. corporis and to a lesser extent B. melaninogenicus; B. loescheii did not show proteolytic activity. When culture filtrates were tested, B. gingivalis showed high cell free proteolytic activity, whereas the other species had only very weak cell free activity. Growth curves of B. gingivalis revealed two distinct proteolytic activities; general proteolytic activity was found during the logarithmic growth phase, whereas a second peak containing high collagenolytic activity was found after prolonged incubation of cells showing autolysis.     

Ets proteins: new factors that regulate immunoglobulin heavy-chain gene expression.

We used a DNA-protein interaction screening method to isolate a cDNA, Erg-3, whose product binds to a site, designated pi, present in the immunoglobulin (Ig) heavy-chain gene enhancer. Erg-3 is an alternatively spliced product of the erg gene and contains an Ets DNA-binding domain. Fli-1 and PU.1, related Ets proteins, also bind to the same site. In addition, PU.1 binds to a second site, designated microB, in the Ig heavy-chain enhancer. We demonstrate that the pi binding site is crucial for Ig heavy-chain gene enhancer function. In addition, we show that Erg-3 and Fli.1, but not PU.1, can activate a reporter construct containing a multimer of protein-binding sites, synergistically with helix-loop-helix protein E12. We discuss how combinatorial interactions between members of the helix-loop-helix and Ets families may account for the tissue specificity of these proteins.     

Effect of culture filtrates of black-pigmented Bacteroides species on the matrix production of chick embryo chondrocytes in vitro

Antonie van Leeuwenhoek -     

IMPROV-ED trial: eHealth programme for faster recovery and reduced healthcare utilisation after CABG

Netherlands Heart Journal - After coronary artery bypass grafting (CABG), healthcare utilisation is high and is partly unplanned. eHealth applications have been proposed to reduce healthcare...     

Better survival after transcatheter aortic valve replacement by process improvements

ObjectiveThe aim of this study is to assess the effects on procedural, 30-day, and 1‑year all-cause mortality by a newly introduced quality improvement strategy in patients after transcatheter aortic valve replacement (TAVR).MethodsIn October 2015, a coherent set of quality improving interventions with respect to patient geriatric screening, general diagnostic examination and safety of the procedure was implemented at a single centre in the Netherlands. Patients undergoing TAVR in 2013–2018 were included for retrospective analysis. Mortality was assessed in the pre-quality improvement strategy cohort (January 2013 to October 2015; cohort A) and in the post-quality improvement strategy cohort (November 2015 to December 2018; cohort B). Logistic regression analysis was used to estimate the influence of patient and procedural characteristics on the results of the quality improvement strategy in terms of procedural, 30-day, and 1‑year all-cause mortality.ResultsIn total, 806 patients were analysed with 274 patients in cohort A and 532 patients in cohort B. After introduction of the quality improvement strategy, procedural (4.4% to 1.3%, p < 0.01), 30-day (8.4% to 2.7%, p < 0.01) and 1‑year (16.4% to 8.5%, p < 0.01) all-cause mortality significantly decreased. Multivariate regression analysis showed that the quality improvement strategy also significantly reduced 30-day (odds ratio [OR] 0.19, 95% confidence interval [CI] 0.09–0.42) and 1‑year (OR 0.38, 95% CI 0.24–0.61) all-cause mortality if corrected for patient characteristics.ConclusionStructural meetings on evaluation of outcomes highlight potential areas for improvement and subsequent outcome-based quality improvement initiatives can result in lower procedural, 30-day, and 1‑year all-cause mortality.Electronic supplementary materialThe online version of this article (10.1007/s12471-020-01526-7) contains supplementary material, which is available to authorized users.     

Ablation of PLB exacerbates ischemic injury to a lesser extent in female than male mice: protective role of NO

Recent studies suggest a role for phospholamban phosphorylation during ischemia and reperfusion. The role of phospholamban in ischemia was studied by subjecting hearts from male and female wild-type (MWT/FWT) and phospholamban-knockout (MKO/FKO) mice to 20 min of ischemia-40 min of reperfusion while (31)P NMR spectra were acquired. ATP and pH values fell lower during ischemia, and postischemic contractility was less, in MKO and FKO versus WT hearts. After shorter ischemia (15 min), recoveries of contraction, ATP, and pH were greater in FKO than MKO hearts. To examine the role of nitric oxide (NO) synthases (NOS) in the protection in FKO versus MKO hearts, we utilized 1 microM l-NAME, a NOS inhibitor, or 100 microM S-nitroso-N-acetylpenicillamine (SNAP), an NO donor. Recoveries of function, ATP, and pH were less in l-NAME-treated FKO than untreated FKO hearts and greater in SNAP-treated MKO than untreated MKO hearts. In conclusion, phospholamban ablation increased ischemic injury in both males and females; however, female hearts were less susceptible than male hearts. Protection in females was decreased by a NOS inhibitor and mimicked in males by an NO donor, implying that protection was NOS mediated.