bluuebunny/crossref_metadata_2025_split huggingface dataset:
Core of the partner switching signalling mechanism is conserved in the obligate intracellular pathogen Chlamydia trachomatis
Authors: Hua Lei , Hefty P. Scott , Lee Young Jin , Lee Young Moo , Stephens Richard S. , Price Chester W. 
Published: December 2005

SummaryChlamydia trachomatis is an obligate intracellular bacterial pathogen that can cause sexually transmitted and ocular diseases in humans. Its biphasic developmental cycle and ability to evade host‐cell defences suggest that the organism responds to external signals, but its genome encodes few recognized signalling pathways. One such pathway is predicted to function by a partner switching mechanism, in which key protein interactions are controlled by serine phosphorylation. From genome analysis this mechanism is both ancient and widespread among eubacteria, but it has been experimentally characterized in only a few. C. trachomatis has no system of genetic exchange, so here an in vitro approach was used to establish the activities and interactions of the inferred partner switching components: the RsbW switch protein/kinase and its RsbV antagonists. The C. trachomatis genome encodes two RsbV paralogs, RsbV1 and RsbV2. We found that each RsbV protein was specifically phosphorylated by RsbW, and tandem mass spectrometry located the phosphoryl group on a conserved serine residue. Mutant RsbV1 and RsbV2 proteins in which this conserved serine was changed to alanine could activate the yeast two‐hybrid system when paired with RsbW, whereas mutant proteins bearing a charged aspartate failed to activate. From this we infer that the phosphorylation state of RsbV1 and RsbV2 controls their interaction with RsbW in vivo. This experimental demonstration that the core of the partner switching mechanism is conserved in C. trachomatis indicates that its basic features are maintained over a large evolutionary span. Although the molecular target of the C. tra‐chomatis switch remains to be identified, based on the predicted properties of its input phosphatases we propose that the pathway controls an important aspect of the developmental cycle within the host, in response to signals external to the C. trachomatis cytoplasmic membrane.
Evidence for siderophore‐dependent iron acquisition in group B streptococcus
Authors: Clancy Anne , Loar Jesse W. , Speziali Craig D. , Oberg Michael , Heinrichs David E. , Rubens Craig E. 
Published: December 2005

SummaryMutagenesis of group B streptococcus (GBS) with TnphoZ, a transposon designed to identify secreted protein genes, identified the gene homologues fhuD and fhuG. The encoded proteins participate in siderophore (hydroxamate)‐dependent iron(III) transport in other bacterial species. Sequence analysis of the genome determined that fhuD and fhuG are members of a polycistronic operon comprised of four genes, fhuCDBG, that encode a putative ATPase, cell surface receptor and two transmembrane proteins respectively. We hypothesized that FhuD was a siderophore receptor. Western analysis of cell extracts localized FhuD to the bacterial cell membrane. Fluorescence quenching experiments determined that purified FhuD bound hydroxamate‐type siderophores. FhuD displayed highest affinity for iron(III)‐desferroxamine, with a KD (µM) = 0.05, identical to that described for FhuD2 from Staphylococcus aureus. The role of Fhu in siderophore‐iron transport was also characterized. A fhu mutant, ACFhu1, was equally sensitive to the iron‐dependent antibiotic streptonigrin as the wild‐type strain, suggesting that ACFhu1 was not reduced for intracellular iron concentrations in the absence of exogenous siderophore. However, ACFhu1 transported significantly less siderophore‐bound iron in 55Fe accumulation assays. These data provide the first evidence of siderophore‐mediated iron acquisition by GBS.
Heterocyst differentiation and pattern formation in cyanobacteria: a chorus of signals
Authors: Zhang Cheng‐Cai , Laurent Sophie , Sakr Samer , Peng Ling , Bédu Sylvie 
Published: December 2005

SummaryHeterocyst differentiation in filamentous cyanobacteria provides an excellent prokaryotic model for studying multicellular behaviour and pattern formation. In Anabaena sp. strain PCC 7120, for example, 5–10% of the cells along each filament are induced, when deprived of combined nitrogen, to differentiate into heterocysts. Heterocysts are specialized in the fixation of N2 under oxic conditions and are semi‐regularly spaced among vegetative cells. This developmental programme leads to spatial separation of oxygen‐sensitive nitrogen fixation (by heterocysts) and oxygen‐producing photosynthesis (by vegetative cells). The interdependence between these two cell types ensures filament growth under conditions of combined‐nitrogen limitation. Multiple signals have recently been identified as necessary for the initiation of heterocyst differentiation, the formation of the heterocyst pattern and pattern maintenance. The Krebs cycle metabolite 2‐oxoglutarate (2‐OG) serves as a signal of nitrogen deprivation. Accumulation of a non‐metabolizable analogue of 2‐OG triggers the complex developmental process of heterocyst differentiation. Once heterocyst development has been initiated, interactions among the various components involved in heterocyst differentiation determine the developmental fate of each cell. The free calcium concentration is crucial to heterocyst differentiation. Lateral diffusion of the PatS peptide or a derivative of it from a developing cell may inhibit the differentiation of neighbouring cells. HetR, a protease showing DNA‐binding activity, is crucial to heterocyst differentiation and appears to be the central processor of various early signals involved in the developmental process. How the various signalling pathways are integrated and used to control heterocyst differentiation processes is a challenging question that still remains to be elucidated.
Heat sensitivity of photosynthetic electron transport varies during the day due to changes in sugars and osmotic potential
Authors: HÜVE KATJA , BICHELE IRINA , TOBIAS MARI , NIINEMETS ÜLO 
Published: December 2005

ABSTRACTIn water‐stressed leaves, accumulation of neutral osmotica enhances the heat tolerance of photosynthetic electron transport. There are large diurnal and day‐to‐day changes in leaf sugar content because of variations in net photosynthetic production, respiration and retranslocation. To test the hypothesis that diurnal and day‐to‐day variations in leaf sugar content and osmotic potential significantly modify the responses to temperature of photosynthetic electron transport rate, we studied chlorophyll fluorescence rise temperatures (i.e. critical temperatures at break‐points in fluorescence versus temperature response curves, corresponding to enhanced damage of PSII centers and detachment of pigment‐binding complexes) in the dark at a background of weak far‐red light (TFR) and under actinic light (TL), and responses of foliar photosynthetic electron transport rate to temperature using gas‐exchange and chlorophyll fluorescence techniques in the temperate tree Populus tremula L. Sucrose and sorbitol feeding experiments demonstrated strong increases of fluorescence rise temperatures TFR and TL with decreasing leaf osmotic potential and increasing internal sugar concentration. Similar TFR and TL changes were observed in response to natural variation in leaf sugar concentration throughout the day. Increases in leaf sugar concentration led to an overall down‐regulation of the rate of photosynthetic electron transport (J), but increases in the optimum temperature (Topt) of J. For the entire dataset, Topt varied from 33.8 °C to 43 °C due to natural variation in sugars and from 33.8 °C to 52.6 °C in the sugar feeding experiments, underscoring the importance of sugars in modifying the response of J to temperature. However, the correlations between the sugar concentration and fluorescence rise temperature varied between the days. This variation in fluorescence rise temperature was best explained by the average temperature of the preceding 5 or 6 days. In addition, there was a significant year‐to‐year variation in heat sensitivity of photosynthetic electron transport that was associated with year‐to‐year differences in endogenous sugar content. Our data demonstrate a diurnal variation in leaf heat tolerance due to changes in sugar concentration, but they also show that this short‐term modification in heat tolerance is superimposed by long‐term changes in heat resistance driven by average temperature of preceding days.
Long‐term acclimatization of hydraulic properties, xylem conduit size, wall strength and cavitation resistance inPhaseolus vulgarisin response to different environmental effects
Authors: HOLSTE ELLEN K. , JERKE MEGAN J. , MATZNER STEVEN L. 
Published: December 2005

ABSTRACTPhaseolus vulgarisgrown under various environmental conditions was used to assess long‐term acclimatization of xylem structural characteristics and hydraulic properties. Conduit diameter tended to be reduced and ‘wood’ density (of ‘woody’ stems) increased under low moisture (‘dry’), increased soil porosity (‘porous soil’) and low phosphorus (‘low P’) treatments. Dry and low P had the largest percentage of small vessels. Dry, low light (‘shade’) and porous soil treatments decreasedP50(50% loss in conductivity) by 0.15–0.25 MPa (greater cavitation resistance) compared with ‘controls’. By contrast, low P increasedP50by 0.30 MPa (less cavitation resistance) compared with porous soil (the control for low P). Changes in cavitation resistance were independent of conduit diameter. By contrast, changes in cavitation resistance were correlated with wood density for the control, dry and porous soil treatments, but did not appear to be a function of wood density for the shade and low P treatments. In a separate experiment comparing control and porous soil plants, stem hydraulic conductivity (kh), specific conductivity (ks), leaf specific conductivity (LSC), total pot water loss, plant biomass and leaf area were all greater for control plants compared to porous soil plants. Porous soil plants, however, demonstrated higher midday stomatal conductance to water vapour (gs), apparently because they experienced proportionally less midday xylem cavitation.
Senescence‐specific regulation of catalases in Arabidopsis thaliana (L.) Heynh
Authors: ZIMMERMANN PETRA , HEINLEIN CHRISTINA , ORENDI GABRIELE , ZENTGRAF ULRIKE 
Published: December 2005

ABSTRACTOxygen free radicals are thought to play an essential role in senescence, especially those derived from peroxisomes. Therefore, the activities of different isoforms of the peroxisomal hydrogen peroxide (H2O2)‐scavenging enzyme catalase (CAT) were analysed during senescence of Arabidopsis. CAT2 activity decreased with bolting time parallel with cytosolic ascorbate peroxidase 1 (APX1) activity before loss of chlorophyll could be measured. At the same time point, the H2O2 content increased. Subsequently, the stress‐inducible CAT3 isoform was activated and APX1 activity was recovered, accompanied by a decline of the H2O2 content. In very late stages, low activities of the seed‐specific CAT1 became detectable in leaves, but H2O2 increased again. Further analyses of CAT expression by promoter : β‐glucuronidase (GUS) fusions in transgenic plants revealed a vasculature‐specific CAT3 expression, whereas CAT2 expression turned out to be specific for photosynthetic active tissues. CAT2 expression is down‐regulated during leaf senescence, while CAT3 expression is induced with age and corresponds to an accumulation of H2O2 in the vascular bundles. CAT2 down‐regulation on the transcriptional level appears as the initial step in creating the H2O2 peak during bolting time, while the decrease in APX1 activity might only be a secondary and amplifying effect.
Immunomodulation in Type 1 Diabetes by NBI‐6024, an Altered Peptide Ligand of the Insulin B(9−23) Epitope
Authors: Alleva D. G. , Maki R. A. , Putnam A. L. , Robinson J. M. , Kipnes M. S. , Dandona P. , Marks J. B. , Simmons D. L. , Greenbaum C. J. , Jimenez R. G. , Conlon P. J. , Gottlieb P. A. 
Published: December 2005

AbstractNBI‐6024 is an altered peptide ligand (APL) corresponding to the 9–23 amino acid region of the insulin B chain (B(9−23)), an epitope recognized by inflammatory interferon‐γ‐producing T helper (Th)1 lymphocytes in type 1 diabetic patients. Immunomodulatory effects of NBI‐6024 administration in recent‐onset diabetic patients in a phase I clinical trial (NBI‐6024‐0003) were measured in peripheral blood mononuclear cells using the enzyme‐linked immunosorbent spot assay. Analysis of the mean magnitude of cytokine responses to B(9−23) and NBI‐6024 for each cohort showed significant increases in interleukin‐5 responses (a Th2 regulatory phenotype) in cohorts that received APL relative to those receiving placebo. A responder analysis showed that Th1 responses to B(9−23) and NBI‐6024 were observed almost exclusively in the placebo‐treated diabetic population but not in nondiabetic control subjects and that APL administration (five biweekly subcutaneous injections) significantly and dose‐dependently reduced the percentage of patients with these Th1 responses. The results of this phase I clinical study strongly suggest that NBI‐6024 treatment shifted the Th1 pathogenic responses in recent‐onset type 1 diabetic patients to a protective Th2 regulatory phenotype. The significance of these findings on the clinical outcome of disease is currently under investigation in a phase II multidose study.
Phylogenetic relationships and evolution of cleaning behaviour in the family Labridae
Authors: Arnal C. , Verneau O. , Desdevises Y. 
Published: December 2005

Abstract
The family Labridae contains numerous fishes known to act as cleaners in the wild. Previous studies suggested that a small body size and specific colour patterns may be prerequisites for cleaning. We investigated whether cleaning behaviour is linked to particular fish phenotypes. We first present a phylogeny based on partial 12S rRNA gene sequences of 32 wrasses sampled from different localities in the Indo-Pacific and Atlantic oceans, and in the Mediterranean Sea. Secondly, descriptive data (fish body size, fish body shape and fish body colour patterns) were analyzed in a phylogenetic context using comparative methods. We found no relationship between fish cleaning behaviour and fish body size and shape, but instead a correlation between cleaning behaviour and the presence of a dark lateral stripe within wrasses. Our results suggest that the evolution of cleaning depends upon the presence of a dark median lateral stripe on the fish body surface.
Endoscopic variceal ligation versus propranolol in prophylaxis of first variceal bleeding in patients with cirrhosis
Authors: LAY CHII‐SHYAN , TSAI YANG‐TE , LEE FA‐YAUH , LAI YI‐LIANG , YU CHENG‐JU , CHEN CHIH‐BIN , PENG CHENG‐YUAN 
Published: December 2005

AbstractBackground and Aim: To compare the efficacy and safety of endoscopic variceal ligation (EVL) with propranolol in prophylaxis on the rate of first esophageal variceal bleeding in patients with cirrhosis.Methods: A prospective, randomized trial was conducted in 100 cirrhotic patients with no history of previous upper gastrointestinal bleeding and with esophageal varices endoscopically judged to be at high risk of hemorrhage. The end‐points of the study were bleeding and death.Results: Life‐table curves showed that prophylactic EVL and propranolol were similarly effective for primary prophylaxis of variceal bleeding (11/50 [22%]vs12/50 [24%];P = 0.68) and overall mortality (14/50 [28%]vs12/50 [24%];P = 0.49). The 2‐year cumulative bleeding rate was 18% (9/50) in the EVL group and 16% (8/50) in the propranolol group. The 2‐year cumulative mortality rate was 28% (14/50) in the EVL group and 24% (12/50) in the propranolol group. Comparison of Kaplan‐Meier estimates of the time to death of both groups showed no significant difference in mortality in both groups (P = 0.86). Patients undergoing EVL had few treatment failures and died mainly of hepatic failure. In the propranolol group, the mean daily dosage of the drug was 68.2 ± 32.8 mg, which was sufficient to reduce the pulse rate by 25%. 20% of patients withdrew from propranolol treatment due to adverse events.Conclusions: Prophylaxis EVL is as effective and as safe as treatment with propranolol in decreasing the incidence of first variceal bleeding and death in cirrhotic patients with high‐risk esophageal varices.
Measurement of parenchymal function and bile duct flow in primary sclerosing cholangitis using dynamic 99mTc‐HIDA SPECT
Authors: JONAS EDUARD , NÄSLUND ERIK , FREEDMAN JACOB , BEFRITS RAGNAR , BLOMQVIST LENNART , SIÖSTEEN ANNA‐KARIN , JACOBSSON HANS , HULTCRANTZ ROLF 
Published: December 2005

AbstractBackground and Aim:  Primary sclerosing cholangitis is a chronic cholestatic disease characterized by obliterative fibrosis of intrahepatic and/or extrahepatic bile ducts. The unpredictable clinical course of the disease can be relentless, leading to premature death in a large percentage of patients. Prognostic index formulas, the revised Mayo model being the most frequently used, have been developed to predict clinical course and prognosis. The aim of this study was to investigate the potential value of dynamic 99mTc‐HIDA SPECT in patients with primary sclerosing cholangitis by correlating scintigraphic results with cholangiographic and biochemical findings and prognostic scoring systems used in clinical practice.Methods:  In 18 patients with primary sclerosing cholangitis, segmental parenchymal and bile duct functions were measured using dynamic 99mTc‐HIDA SPECT. Quantitative scintigraphic results were compared to cholangiographic findings, as graded by a biliary classification system, the Child–Pugh score and revised Mayo prognostic score, as well as the individual biochemical parameters included in the scoring systems.Results:  In individual segments, scintigraphic quantitative parameters indicative of bile flow showed a statistically significant correlation with the state of the bile‐flow path for the respective segments as assessed by the biliary classification system. The revised Mayo score correlated with the scintigraphic quantitative parameters indicative of parenchymal function and bile flow as calculated for the whole liver.Conclusions:  Dynamic 99mTc‐HIDA SPECT, capable of assessing different aspects of liver function for the total liver, as well as for individual segments, has potential value in the management of patients with primary sclerosing cholangitis.
Providing guidelines and education is not enough: an audit of gentamicin use at The Royal Melbourne Hospital
Authors: Leong C. L. , Buising K. , Richards M. , Robertson M. , Street A. 
Published: December 2005

AbstractBackground: Aminoglycoside antibiotics are commonly prescribed for the treatment of Gram‐negative infections. Appropriate dosing and therapeutic monitoring of aminoglycosides are important because these agents have a narrow therapeutic index.Aim: To audit gentamicin use at our hospital, focusing on selection of the initial dose and therapeutic monitoring practices, and to compare the results against recommendations in the existing hospital aminoglycoside guidelines, which had recently been promoted to doctors.Methods: This audit included all inpatients receiving gentamicin at The Royal Melbourne Hospital from 1 February to 12 March 2004. The principal researcher checked the drug charts of all inpatients to identify those receiving gentamicin and collected data from the medical records and the pathology database. Doses were considered ‘concordant’ if the dose given was within the recommended dosing range ±20 mg.Results: A total of 132 courses of gentamicin was included in the study. Gentamicin was prescribed for prophylaxis in 31.1% of courses. Thirty‐six per cent of patients prescribed gentamicin were more than 65 years of age. Eighty‐two per cent of the gentamicin used therapeutically was given as a single daily dose. Sixty‐six per cent of gentamicin initial dosing was not in accordance with existing hospital guidelines. Seventy‐seven per cent of gentamicin courses requiring therapeutic drug monitoring received such monitoring; however, in only 8.8% of these was the monitoring conducted according to guidelines.Conclusion: Aminoglycoside prescribing practices at our hospital are suboptimal, despite ready access to prescribing guidelines. Provision of a guideline and education sessions with doctors do not necessarily lead to widespread adoption of recommended practices. We suggest that changes to hospital systems related to prescribing and monitoring of aminoglycosides are required.
Epidemiology of the functional gastrointestinal disorders diagnosed according to Rome II criteria: an Australian population‐based study
Authors: Boyce P. M. , Talley N. J. , Burke C. , Koloski N. A. 
Published: December 2005

AbstractBackground: Population‐based studies of the prevalence of all functional gastrointestinal disorders (FGID) using the Rome II criteria are lacking. It is also not certain whether subjects who meet the Rome II criteria for an FGID are different in terms of demographic and psychological characteristics from those subjects meeting exclusively the more restrictive Rome I criteria.Aim: To determine whether using the more restrictive Rome I criteria would result in a more biologically determined group of FGID than when the Rome II is applied.Methods: Subjects included individuals aged 18 years and older (n = 1225) from the Penrith population who were initially surveyed with the Penrith District Health Survey in 1997. Subjects were sent a self‐report questionnaire that contained items on gastrointestinal symptoms applying the Rome II criteria. Subjects were also assessed on psychological and personality factors and on physical and mental functioning.Results: A total of 36.1% (n = 275) of respondents was diagnosed with an FGID according to Rome II criteria. The five most prevalent FGID were functional heartburn (10.4%), irritable bowel syndrome (8.9%), functional incontinence (7.6%), proctalgia fugax (6.5%) and functional chest pain (5.1%). Subjects meeting Rome II only criteria for FGID scored significantly higher on measures of psychological caseness and emotionality than Rome I only subjects, and these were independently associated with meeting Rome I only versus Rome II only criteria for FGID.Conclusion: The Rome II criteria FGID are common and do not appear to identify a vastly different group of FGID sufferers compared with the earlier Rome I criteria.
Secretion of brain‐derived neurotrophic factor from PC12 cells in response to oxidative stress requires autocrine dopamine signaling
Authors: Wang Hong , Yuan Guoxiang , Prabhakar Nanduri R. , Boswell Mark , Katz David M. 
Published: December 2005

AbstractExpression of brain‐derived neurotrophic factor (BDNF) is sensitive to changes in oxygen availability, suggesting that BDNF may be involved in adaptive responses to oxidative stress. However, it is unknown whether or not oxidative stress actually increases availability of BDNF by stimulating BDNF secretion. To approach this issue we examined BDNF release from PC12 cells, a well‐established model of neurosecretion, in response to hypoxic stimuli. BDNF secretion from neuronally differentiated PC12 cells was strongly stimulated by exposure to intermittent hypoxia (IH). This response was inhibited by N‐acetyl‐l‐cysteine, a potent scavenger of reactive oxygen species (ROS) and mimicked by exogenous ROS. IH‐induced BDNF release requires activation of tetrodotoxin sensitive Na+ channels and Ca2+ influx through N‐ and L‐type channels, as well as mobilization of internal Ca2+ stores. These results demonstrate that oxidative stress can stimulate BDNF release and that underlying mechanisms are similar to those previously described for activity‐dependent BDNF secretion from neurons. Surprisingly, we also found that IH‐induced secretion of BDNF was blocked by dopamine D2 receptor antagonists or by inhibition of dopamine synthesis with α‐methyl‐p‐tyrosine. These data indicate that oxidative stress can stimulate BDNF release through an autocrine or paracrine loop that requires dopamine receptor activation.