bluuebunny/crossref_metadata_2025_split huggingface dataset:
Regulation of the Hypoxic Response in Candida albicans
Authors: Synnott John M. , Guida Alessandro , Mulhern-Haughey Siobhan , Higgins Desmond G. , Butler Geraldine 
Published: September 2010

ABSTRACTThe regulation of the response ofCandida albicansto hypoxic (low-oxygen) conditions is poorly understood. We used microarray and other transcriptional analyses to investigate the role of the Upc2 and Bcr1 transcription factors in controlling expression of genes involved in cell wall metabolism, ergosterol synthesis, and glycolysis during adaptation to hypoxia. Hypoxic induction of the ergosterol pathway is mimicked by treatment with sterol-lowering drugs (ketoconazole) and requiresUPC2. Expression of three members of the family CFEM (common in severalfungalextracellularmembranes) of cell wall genes (RBT5,PGA7, andPGA10) is also induced by hypoxia and ketoconazole and requires bothUPC2andBCR1. Expression of glycolytic genes is induced by hypoxia but not by treatment with sterol-lowering drugs, whereas expression of respiratory pathway genes is repressed. However, Upc2 does not play a major role in regulating expression of genes required for central carbon metabolism. Our results indicate that regulation of gene expression in response to hypoxia inC. albicansis complex and is signaled both via lowered sterol levels and other unstudied mechanisms. We also show that induction of filamentation under hypoxic conditions requires the Ras1- and Cdc35-dependent pathway.
Fitness Effects of Replichore Imbalance in
Salmonella enterica
Authors: Matthews T. David , Maloy Stanley 
Published: September 2010

ABSTRACT

A fitness cost due to imbalanced replichores has been proposed to provoke chromosome rearrangements in
Salmonella enterica
serovars. To determine the impact of replichore imbalance on fitness, the relative fitness of isogenic
Salmonella
strains containing transposon-held duplications of various sizes and at various chromosomal locations was determined. Although duplication of certain genes influenced fitness, a replichore imbalance of up to 16° did not affect fitness.
Chlamydia trachomatisSerovar L2 Can Utilize Exogenous Lipoic Acid through the Action of the Lipoic Acid Ligase LplA1
Authors: Ramaswamy Aishwarya V. , Maurelli Anthony T. 
Published: September 2010

ABSTRACTLipoic acid is an essential protein bound cofactor that is vital for the functioning of several important enzymes involved in central metabolism. Genomes of all sequenced chlamydiae show the presence of two genes encoding lipoic acid ligases and one gene encoding a lipoate synthase. However, the roles of these proteins in lipoic acid utilization or biosynthesis have not yet been characterized. The two distinct lipoic acid ligases inChlamydia trachomatisserovar L2, LplA1Ctand LplA2Ct(encoded by the open reading framesctl0537andctl0761) display moderate identity withEscherichia coliLplA (30 and 27%, respectively) but possess amino acid sequence motifs that are well conserved among all lipoyl protein ligases. The putative lipoic acid synthase LipACt, encoded byctl0815,is ca. 43% identical to theE. coliLipA homolog. We demonstrate here the presence of lipoylated proteins inC. trachomatisserovar L2 and show that the lipoic acid ligase LplA1Ctis capable of utilizing exogenous lipoic acid for the lipoylation Therefore, host-derived lipoic acid may be important for intracellular growth and development. Based on genetic complementation in a surrogate host, our study also suggests that theC. trachomatisserovar L2 LipA homolog may not be functionalin vivo.
Identification of YsrT and Evidence that YsrRST Constitute a Unique Phosphorelay System inYersinia enterocolitica
Authors: Walker Kimberly A. , Obrist Markus W. , Mildiner-Earley Shirly , Miller Virginia L. 
Published: September 2010

ABSTRACTTwo-component systems (TCS) and phosphorelay systems are mechanisms used by bacteria and fungi to quickly adapt to environmental changes to produce proteins necessary for survival in new environments. Bacterial pathogens use TCS and phosphorelay systems to regulate genes necessary to establish infection within their hosts, including type III secretion systems (T3SS). TheYersinia enterocolitica ysaT3SS is activated in response to NaCl by YsrS and YsrR, a putative hybrid sensor kinase and a response regulator, respectively. Hybrid TCS consist of a sensor kinase that typically has three well-conserved sites of phosphorylation: autophosphorylation site H1, D1 within a receiver domain, and H2 in the histidine phosphotransferase (HPt) domain. From H2, the phosphoryl group is transferred to D2 on the response regulator. A curious feature of YsrS is that it lacks the terminal HPt domain. We report here the identification of the HPt-containing protein (YsrT) that provides this activity for the Ysr system. YsrT is an 82-residue protein predicted to be cytosolic and α-helical in nature and is encoded by a gene adjacent toysrS. To demonstrate predicted functions of YsrRST as a phosphorelay system, we introduced alanine substitutions at H1, D1, H2, and D2 and tested the mutant proteins for the ability to activate aysaE-lacZreporter. As expected, substitutions at H1, H2, and D2 resulted in a loss of activation ofysaEexpression. This indicates an interruption of normal protein function, most likely from loss of phosphorylation. A similar result was expected for D1; however, an intriguing “constitutive on” phenotype was observed. In addition, the unusual feature of a separate HPt domain led us to compare the sequences surrounding theysrS-ysrTjunction in severalYersiniastrains. In every strain examined,ysrTis a separate gene, leading to speculation that there is a functional advantage to YsrT being an independent protein.
Coxiella burnetii
Expresses a Functional Δ24 Sterol Reductase
Authors: Gilk Stacey D. , Beare Paul A. , Heinzen Robert A. 
Published: September 2010

ABSTRACT

Coxiella burnetii
, the etiological agent of human Q fever, occupies a unique niche inside the host cell, where it replicates in a modified acidic phagolysosome or parasitophorous vacuole (PV). The PV membrane is cholesterol-rich, and inhibition of host cholesterol metabolism negatively impacts PV biogenesis and pathogen replication. The precise source(s) of PV membrane cholesterol is unknown, as is whether the bacterium actively diverts and/or modifies host cell cholesterol or sterol precursors.
C. burnetii
lacks enzymes for
de novo
cholesterol biosynthesis; however, the organism encodes a eukaryote-like Δ24 sterol reductase homolog, CBU1206. Absent in other prokaryotes, this enzyme is predicted to reduce sterol double bonds at carbon 24 in the final step of cholesterol or ergosterol biosynthesis. In the present study, we examined the functional activity of CBU1206. Amino acid alignments revealed the greatest sequence identity (51.7%) with a Δ24 sterol reductase from the soil amoeba
Naegleria gruberi.
CBU1206 activity was examined by expressing the protein in a
Saccharomyces cerevisiae erg4
mutant under the control of a galactose-inducible promoter. Erg4 is a yeast Δ24 sterol reductase responsible for the final reduction step in ergosterol synthesis. Like Erg4-green fluorescent protein (GFP), a CBU1206-GFP fusion protein localized to the yeast endoplasmic reticulum. Heterologous expression of CBU1206 rescued
S. cerevisiae erg4
sensitivity to growth in the presence of brefeldin A and cycloheximide and resulted in new synthesis of ergosterol. These data indicate CBU1206 is an active sterol reductase and suggest the enzyme may act on host sterols during
C. burnetii
intracellular growth.
The
Staphylococcus aureus
Autoinducer-2 Synthase LuxS Is Regulated by Ser/Thr Phosphorylation
Authors: Cluzel Marie-Eve , Zanella-Cléon Isabelle , Cozzone Alain J. , Fütterer Klaus , Duclos Bertrand , Molle Virginie 
Published: September 2010

ABSTRACT

The
Staphylococcus aureus
autoinducer-2 (AI-2) producer protein LuxS is phosphorylated by the Ser/Thr kinase Stk1 at a unique position, Thr14. The enzymatic activity of the phosphorylated isoform of LuxS was abrogated compared to that of nonphosphorylated LuxS, thus providing the first evidence of an AI-2-producing enzyme regulated by phosphorylation and demonstrating that
S. aureus
possesses an original and specific system for controlling AI-2 synthesis.
Interaction of the Colicin K Bactericidal Toxin with Components of Its Import Machinery in the Periplasm ofEscherichia coli
Authors: Barnéoud-Arnoulet Aurélie , Gavioli Marthe , Lloubès Roland , Cascales Eric 
Published: September 2010

ABSTRACTColicins are bacterial antibiotic toxins produced byEscherichia colicells and are active againstE. coliand closely related strains. To penetrate the target cell, colicins bind to an outer membrane receptor at the cell surface and then translocate their N-terminal domain through the outer membrane and the periplasm. Once fully translocated, the N-terminal domain triggers entry of the catalytic C-terminal domain by an unknown process. Colicin K uses the Tsx nucleoside-specific receptor for binding at the cell surface, the OmpA protein for translocation through the outer membrane, and the TolABQR proteins for the transit through the periplasm. Here, we initiated studies to understand how the colicin K N-terminal domain (KT) interacts with the components of its transit machine in the periplasm. We first produced KT fused to a signal sequence for periplasm targeting. Upon production of KT in wild-type strains, cells became partly resistant to Tol-dependent colicins and sensitive to detergent, released periplasmic proteins, and outer membrane vesicles, suggesting that KT interacts with and titrates components of its import machine. Using a combination ofin vivocoimmunoprecipitations andin vitropulldown experiments, we demonstrated that KT interacts with the TolA, TolB, and TolR proteins. For the first time, we also identified an interaction between the TolQ protein and a colicin translocation domain.
Mutational Analysis of the Transmembrane Helix 2-HAMP Domain Connection in the
Escherichia coli
Aspartate Chemoreceptor Tar
Authors: Wright Gus A. , Crowder Rachel L. , Draheim Roger R. , Manson Michael D. 
Published: September 2010

ABSTRACT
Transmembrane helix 2 (TM2) of the Tar chemoreceptor undergoes an inward piston-like displacement of 1 to 3 Å upon binding aspartate. This signal is transmitted to the kinase-control module via the HAMP domain. Within Tar, the HAMP domain forms a parallel four-helix bundle consisting of a dimer of two amphipathic helices connected by a flexible linker. In the nuclear magnetic resonance structure of an archaeal HAMP domain, residues corresponding to the MLLT sequence between Arg-214 at the end of TM2 and Pro-219 of Tar are an N-terminal helical extension of AS1. We modified this region to test whether it behaves as a continuous helical connection between TM2 and HAMP. First, one to four Gly residues were inserted between Thr-218 and Pro-219. Second, the MLLT sequence was replaced with one to nine Gly residues. Third, the sequence was shortened or extended with residues compatible with helix formation. Cells expressing receptors in which the MLLT sequence was shortened to MLL or in which the MLLT sequence was replaced by four Gly residues performed good aspartate chemotaxis. Other mutant receptors supported diminished aspartate taxis. Most mutant receptors had biased signal outputs and/or abnormal patterns of adaptive methylation. We interpret these results to indicate that a strong, permanent helical connection between TM2 and the HAMP domain is not necessary for normal transmembrane signaling.
A Putative ABC Transporter, HatABCDE, Is among Molecular Determinants of Pyomelanin Production inPseudomonas aeruginosa
Authors: Hunter Ryan C. , Newman Dianne K. 
Published: September 2010

ABSTRACTPyomelanin overproduction is a common phenotype amongPseudomonas aeruginosaisolates recovered from cystic fibrosis and urinary tract infections. Its prevalence suggests that it contributes to the persistence of the producing microbial community, yet little is known about the mechanisms of its production. Using transposon mutagenesis, we identified factors that contribute to melanogenesis in a clinical isolate ofP. aeruginosa. In addition to two enzymes already known to be involved in its biosynthesis (homogentisate dioxygenase and hydroxyphenylpyruvate dioxygenase), we identified 26 genes that encode regulatory, metabolic, transport, and hypothetical proteins that contribute to the production of homogentisic acid (HGA), the monomeric precursor of pyomelanin. One of these, PA14_57880, was independently identified four times and is predicted to encode the ATP-binding cassette of an ABC transporter homologous to proteins inPseudomonas putidaresponsible for the extrusion of organic solvents from the cytosol. Quantification of HGA production byP. aeruginosaPA14 strains missing the predicted subcomponents of this transporter confirmed its role in HGA production: mutants unable to produce the ATP-binding cassette (PA14_57880) or the permease (PA14_57870) produced substantially less extracellular HGA after growth for 20 h than the parental strain. In these mutants, concurrent accumulation of intracellular HGA was observed. In addition, quantitative real-time PCR revealed that intracellular accumulation of HGA elicits upregulation of these transport genes. Based on their involvement inhomogentisicacidtransport, we rename the genes of this operonhatABCDE.
Differential progression of renal scarring and determinants of late renal recovery in sustained dialysis dependent acute kidney injury secondary to myeloma kidney
Authors: Basnayake Kolitha , Cheung Chee Kay , Sheaff Michael , Fuggle William , Kamel Dia , Nakoinz Sandra , Hutchison Colin A , Cook Mark , Stoves John , Bradwell Arthur R , Cockwell Paul 
Published: September 2010

BackgroundMost cases of dialysis-dependent acute kidney injury due to myeloma cast nephropathy do not recover renal function. Renal biopsy typically shows cast formation, direct tubular injury and interstitial inflammation caused by nephrotoxic monoclonal free light chains (FLC). Established scarring at presentation is rarely severe. There is little data on in situ evolution of renal injury.AimsTo conduct a detailed histological study of four patients with cast nephropathy.MethodsCast nephropathy was confirmed by renal biopsy. Treatment consisted of chemotherapy and high cut-off dialysis to maximise extracorporeal removal of FLC and reduce renal toxicity. All four patients remained dialysis dependent at 6 weeks, at which time they underwent a further biopsy.ResultsThree patients achieved independence from dialysis. Six-week biopsies showed differential changes in chronic damage from no progression, to accelerated progression of scarring from 10% to 42%, despite a rapid and sustained fall in FLC in all patients. In three patients there was a major reduction in intratubular cast numbers; these patients subsequently recovered renal function. In one patient who continued to have high cast formation at 6 weeks there was no subsequent renal recovery.ConclusionsSome FLC clones can promote rapid renal scarring. Significant reductions in cast formation on repeat biopsy may identify the potential for late renal recovery. Early diagnosis and treatment may prove crucial in determining renal recovery. Patients who have not recovered renal function after a period of treatment may be usefully reassessed by repeat biopsy for quantitative analysis of chronic damage and cast numbers.
Relation between coagulation/fibrinolysis and lactate in the course of human septic shock
Authors: Hartemink Koen J , Hack C Erik , Groeneveld A B Johan 
Published: September 2010

BackgroundThe pathogenic role of disseminated intravascular coagulation (DIC) during septic shock is incompletely understood.AimTo study the relation between indicators of DIC and lactate concentrations over time to evaluate whether a coagulation/fibrinolysis imbalance could directly contribute to tissue hypoxygenation.Methods14 consecutive septic shock patients with a pulmonary artery catheter in place were prospectively studied. For 3 days after admission, haemodynamic variables and plasma concentrations of lactate, thrombin–antithrombin complexes, tissue plasminogen activator, plasminogen activator inhibitor (PAI), plasmin–α2-antiplasmin complexes, fibrinogen, and the inflammatory mediators tumour necrosis factor-α and interleukin-6, as well as activated partial thromboplastin time (aPTT), prothrombin time (PT) and platelet counts were serially measured.ResultsEight of the 14 patients died in the intensive care unit. All patients had a hyperdynamic circulation with an increased cardiac index and mild hyperlactataemia. They had prolonged PT, thrombocytopenia and raised inflammatory, coagulation and fibrinolysis variables. The time course of PAI best predicted the time course of lactate, independently of haemodynamics, inflammatory mediators, PT, fibrinogen and platelet counts. High lactate, PAI and PT concentrations persisted in non-survivors compared with survivors.ConclusionsThe course of human septic shock, particularly inhibition of activated fibrinolysis during DIC, may be independently associated with hyperlactataemia; therefore a coagulation/fibrinolysis imbalance may contribute to tissue hypoxygenation and ultimately thereby to demise.
Inter- and intraobserver variation in the histopathological evaluation of early oesophageal adenocarcinoma
Authors: Grotenhuis Brechtje A , van Heijl Mark , ten Kate Fiebo J W , Biermann Katharina , Offerhaus G Johan A , Wijnhoven Bas P L , van Berge Henegouwen Mark I , Tilanus Hugo W , van Lanschot J Jan B 
Published: September 2010

AimsAccording to the classification established by the Japanese Society for Oesophageal Disease, early oesophageal cancer can be subdivided into six successive layers of the mucosa or submucosa, which influences the treatment strategy and prognosis of the individual patient. However, the reproducibility of this classification in terms of inter- and intraobserver variability is unclear.MethodsHistological slides from 105 surgical resection specimens of patients who had undergone oesophagectomy for early oesophageal adenocarcinoma were reviewed independently by three gastrointestinal pathologists, and were classified according to the Japanese criteria (m1/m2/m3/sm1/sm2/sm3 tumours). Inter- and intraobserver variation was determined by κ-statistics.ResultsThe interobserver reproducibility was good between pathologist 1 and 2 (κ=0.61, 95% CI 0.55 to 0.67), and moderate between pathologist 1 and 3 (κ=0.51, 95% CI 0.45 to 0.57) and between pathologist 2 and 3 (κ=0.50, 95% CI 0.38 to 0.61). The intraobserver agreement as assessed by the expert pathologist was good (κ=0.76), with a 95% CI that was interpreted as good to very good (0.67 to 0.85). Most agreement was achieved at the lower (m1) and upper site (sm2, sm3) of the spectrum, whereas the m2 tumours reflected the most discrepant stage. The majority of the observed discrepancy included the variation in one substage only.ConclusionsThe reproducibility of the Japanese classification is good in terms of inter- and intraobserver variability when grading early oesophageal adenocarcinoma on surgical resection specimens. The present data confirm that dedicated gastrointestinal pathologists with broad experience are preferred when grading the resection specimens of patients with early oesophageal adenocarcinoma.
Four years of experience of telemedicine for paediatric care in three Punjab hospitals, North India: achievements and lessons
Authors: Singh Meenu , Das Rashmi Ranjan 
Published: September 2010

Abstract
Children in India constitute a very high risk group from mortality and morbidity due to lack of specialised healthcare. Remote care of paediatric patients by offsite specialists using telemedicine technology is a highly potential solution for coping up with the shortage of specialists in Indian subcontinent. We at a tertiary care teaching hospital in North India assessed the application of telemedicine services for diagnosis and management of paediatric illnesses, through prospective analyses of electronic databases over 4 years. The age groups covered were from newborn up to children of 15 years of age. The outcomes assessed were: feasibility, diagnostic possibilities, management, outcomes, referral and mean costs per patient. The results were as follows: major consultations involved children &lt;5 years age, with neonates contributing to 5.5% of the total consultations. The major system-related problems were: gastrointestinal, respiratory, neurological, infectious and haematological. Referral was advised in 14.3% of cases. Ten percent of children were critically ill and could not have been in a position to be transported safely. Videoconferencing was done in 21.4% patients. There was a paucity of feedback and follow up of these consultations (12% of the total). The total savings for all the consultations per child was ≈1000 Indian rupees (approximately US$22) leaving behind the telemedicine consultation charges. To conclude, telepaediatrics in India is still in its fetal stage. The hurdles and medico-legal issues need to be addressed before the telepaediatrics service is widely accepted in India.
Factors affecting the concentration of electrolyte infusions prepared from stock solutions
Authors: Donaldson Thomas M , Mani Vaithianadan , Wheeler Daniel W 
Published: September 2010

ABSTRACT

Background
Wide variation in the concentrations of electrolyte infusions prepared from stock solutions has previously been reported. Layering of viscous stock electrolyte solutions in their diluent can lead to high concentrations being delivered during the infusion, resulting in potentially very serious medication errors which have caused deaths.

Objective
To determine the safest way of preparing homogenous electrolyte solutions for parenteral infusion.

Methods
The study examined how the concentration of potassium and magnesium varied during infusions after concentrated stock solutions had been diluted to 400 mmol/l with 0.9% sodium chloride. It also examined the use of syringes compared to polyvinyl chloride (PVC) bags, agitating vigorously with a ‘vortex’ mixer compared to inversion, and the influence of allowing the infusions to stand for 24 h before administration. The study was conducted in November 2009.

Results
It was found that, in general, the concentrations of potassium and magnesium solutions are less variable if they are prepared in PVC bags rather than syringes. Vigorous mixing of concentrated stock solutions with diluent and allowing preparations to stand for 24 h also improved the homogeneity of the infusions. However, even with meticulous preparation, some infusions deviated from the expected concentration by more than 10%.

Conclusion
It is recommended that electrolyte infusions are prepared and provided by the pharmaceutical industry in prefilled syringes or bags. Given the likely cost of these products, an alternative would be to prepare infusions in pharmacy in advance, using PVC bags rather than syringes, and that they should be agitated vigorously with a ‘vortex’ mixer.