Discordant 16S and 23S rRNA Gene Phylogenies for the Genus Helicobacter: Implications for Phylogenetic Inference and Systematics

Analysis of 16S rRNA gene sequences has become the primary method for determining prokaryotic phylogeny. Phylogeny is currently the basis for prokaryotic systematics. Therefore, the validity of 16S rRNA gene-based phylogenetic analyses is of fundamental importance for prokaryotic systematics. Discrepancies between 16S rRNA gene analyses and DNA-DNA hybridization and phenotypic analyses have been noted in the genus Helicobacter. To clarify these discrepancies, we sequenced the 23S rRNA genes for 55 helicobacter strains representing 41 taxa (>2,700 bases per sequence). Phylogenetic-tree construction using neighbor-joining, parsimony, and maximum likelihood methods for 23S rRNA gene sequence data yielded stable trees which were consistent with other phenotypic and genotypic methods. The 16S rRNA gene sequence-derived trees were discordant with the 23S rRNA gene trees and other data. Discrepant 16S rRNA gene sequence data for the helicobacters are consistent with the horizontal transfer of 16S rRNA gene fragments and the creation of mosaic molecules with loss of phylogenetic information. These results suggest that taxonomic decisions must be supported by other phylogenetically informative macromolecules, such as the 23S rRNA gene, when 16S rRNA gene-derived phylogeny is discordant with other credible phenotypic and genotypic methods. This study found Wolinella succinogenes to branch with the unsheathed-flagellum cluster of helicobacters by 23S rRNA gene analyses and whole-genome comparisons. This study also found intervening sequences (IVSs) in the 23S rRNA genes of strains of 12 Helicobacter species. IVSs were found in helices 10, 25, and 45, as well as between helices 31′ and 27′. Simultaneous insertion of IVSs at three sites was found in H. mesocricetorum

Patient outcomes after total pancreatectomy: a single centre contemporary experience

AbstractIntroductionTotal pancreatectomy (TP) is associated with significant metabolic abnormalities leading to considerable morbidity. With the availability of modern pancreatic enzyme formulations and improvements in control of diabetes mellitus, the metabolic drawbacks of TP have diminished. As indications for TP have expanded, we examine our results in patients undergoing TP.Materials and methodsRetrospective study of 47 patients undergoing TP from January 2002 to January 2008 was performed. Patient data and clinical outcomes were collected and entered into a database. Disease-free survival and overall survival were estimated using the Kaplan–Meier method.ResultsFifteen males and 32 females with a median age of 70 years underwent TP for non-invasive intraductal papillary mucinous neoplasms (IPMN) (21), pancreatic adenocarcinoma (20), other neoplasm (3), chronic pancreatitis (2) and trauma (1). Median hospital stay and intensive care stay were 11 days and 1 day, respectively. Thirty-day major morbidity and mortality was 19% and 2%, respectively. With a median follow-up length of 23 months, 33 patients were alive at last follow-up. Estimated overall survival at 1, 2 and 3 years for the entire cohort was 80%, 72% and 65%, and for those with pancreatic adenocarcinoma was 63%, 43% and 34%, respectively. Median weight loss at 3, 6 and 12 months after surgery was 6.8kg, 8.5kg and 8.8kg, respectively. Median HbA1c values at 6, 12 and 24 months after surgery were 7.3, 7.5 and 7.7, respectively. Over one-half of the patients required re-hospitalization within 12 months post-operatively.ConclusionTP results in significant metabolic derangements and exocrine insufficiency, diabetic control and weight maintenance remain a challenge and readmission rates are high. Survival in those with malignant disease remains poor. However, the mortality appears to be decreasing and the morbidities associated with TP appear acceptable compared with the benefits of resection in selected patients

Differential effects of dopamine signalling on long-term memory formation and consolidation in rodent brain

BACKGROUND: Using auditory discrimination learning in gerbils, we have previously shown that activation of auditory-cortical D1/D5 dopamine receptors facilitates mTOR-mediated, protein synthesis-dependent mechanisms of memory consolidation and anterograde memory formation. To understand molecular mechanisms of this facilitatory effect, we tested the impact of local pharmacological activation of different D1/D5 dopamine receptor signalling modes in the auditory cortex. To this end, protein patterns in soluble and synaptic protein-enriched fractions from cortical, hippocampal and striatal brain regions of ligand- and vehicle-treated gerbils were analysed by 2D gel electrophoresis and mass spectrometry 24 h after intervention. RESULTS: After auditory-cortical injection of SKF38393 – a D1/D5 dopamine receptor-selective agonist reported to activate the downstream effectors adenylyl cyclase and phospholipase C – prominent proteomic alterations compared to vehicle-treated controls appeared in the auditory cortex, striatum, and hippocampus, whereas only minor changes were detectable in the frontal cortex. In contrast, auditory-cortical injection of SKF83959 – a D1/D5 agonist reported to preferentially stimulate phospholipase C – induced pronounced changes in the frontal cortex. At the molecular level, we detected altered regulation of cytoskeletal and scaffolding proteins, changes in proteins with functions in energy metabolism, local protein synthesis, and synaptic signalling. Interestingly, abundance and/or subcellular localisation of the predominantly presynaptic protein α-synuclein displayed dopaminergic regulation. To assess the role of α-synuclein for dopaminergic mechanisms of memory modulation, we tested the impact of post-conditioning systemic pharmacological activation of different D1/D5 dopamine receptor signalling modes on auditory discrimination learning in α-synuclein-mutant mice. In C57BL/6JOlaHsd mice, bearing a spontaneous deletion of the α-synuclein-encoding gene, but not in the related substrains C57BL/6JCrl and C57BL/6JRccHsd, adenylyl cyclase-mediated signalling affected acquisition rates over future learning episodes, whereas phospholipase C-mediated signalling affected final memory performance. CONCLUSIONS: Dopamine signalling modes via D1/D5 receptors in the auditory cortex differentially impact protein profiles related to rearrangement of cytomatrices, energy metabolism, and synaptic neurotransmission in cortical, hippocampal, and basal brain structures. Altered dopamine neurotransmission in α-synuclein-deficient mice revealed that distinct D1/D5 receptor signalling modes may control different aspects of memory consolidation