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Potts JR, Atkinson S, Aram JA, Tibble J, Davies KA, Verma S. De novo Cryoglobulinaemic Mononeuritis Multiplex during Treatment of Chronic Hepatitis C Infection: A Viral Effect or Induced by Pegylated Interferon Alpha? Case Rep Gastroenterol 2012; 6:155-61. [PMID: 22679403 PMCID: PMC3364041 DOI: 10.1159/000337871] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Abstract
Cryoglobulinaemic mononeuritis multiplex (MNM) is an extrahepatic manifestation of chronic hepatitis C virus (HCV) infection for which interferon-based antiviral therapy is currently the treatment of choice. Rarely MNM can be associated with HCV treatment though generally in the setting of pre-existing cryoglobulinaemia and detectable HCV viraemia. We report an unusual case of de novo MNM occurring late during the course of pegylated interferon and ribavirin therapy for chronic HCV infection, following a prolonged period of viral suppression. The patient had no evidence of cryoglobulinaemia prior to HCV treatment and undetectable HCV RNA levels at the time of presentation with MNM. The case raises the possibility that MNM could develop as an adverse immunomodulatory effect of pegylated interferon therapy.
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Finn M, Sutton D, Atkinson S, Ransome K, Sujenthiran P, Ditcham V, Wakefield P, Meagher S. The aqueduct of Sylvius: a sonographic landmark for neural tube defects in the first trimester. ULTRASOUND IN OBSTETRICS & GYNECOLOGY : THE OFFICIAL JOURNAL OF THE INTERNATIONAL SOCIETY OF ULTRASOUND IN OBSTETRICS AND GYNECOLOGY 2011; 38:640-645. [PMID: 22045650 DOI: 10.1002/uog.10088] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Accepted: 08/15/2011] [Indexed: 05/31/2023]
Abstract
OBJECTIVES To describe a new first-trimester sonographic landmark, posterior displacement of the midbrain and aqueduct of Sylvius, which may be useful in early screening for neural tube defects. METHODS This was a prospective study of 457 normal fetuses at 11 + 0 to 13 + 6 weeks' gestation. We measured the distance from the posterior border of the aqueduct of Sylvius to the anterior border of the occiput (AOS-to-occiput distance) in the axial plane and created a reference range. In the nine fetuses with abnormal midbrain position identified in the first trimester and with neural tube defect subsequently confirmed, we analyzed ultrasound images to determine the position of the aqueduct of Sylvius. RESULTS The lower limit of normal AOS-to-occiput distance (mean minus 2 SD) ranged from 1.7 mm at a crown-rump length (CRL) of 45 mm to 3.7 mm at a CRL of 84 mm. In the nine cases with abnormal position of the midbrain and confirmed neural tube defect, juxtaposition of the midbrain to the occiput was the clue to diagnosis of the spinal abnormality. In all nine cases, the AOS-to-occiput distance was below the established normal range. CONCLUSIONS Examination of the midbrain in an axial plane may prove a reliable marker for the first-trimester diagnosis of neural tube defects. In contrast to recently reported subtle changes in the mid-sagittal view of the posterior cranial fossa, axial imaging of the midbrain reveals striking displacement of this structure, with virtual juxtaposition to the occiput, in fetuses with confirmed open spina bifida. This anatomical distortion of the midbrain can be quantified by measurement of the AOS-to-occiput distance.
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Atkinson S, Arnould JPY, Mashburn KL. Plasma cortisol and thyroid hormone concentrations in pre-weaning Australian fur seal pups. Gen Comp Endocrinol 2011; 172:277-81. [PMID: 21439286 DOI: 10.1016/j.ygcen.2011.03.014] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/12/2010] [Revised: 03/15/2011] [Accepted: 03/16/2011] [Indexed: 10/18/2022]
Abstract
The hormonal factors that influence development from birth to weaning in otariid seals is still largely unknown. In the present study, a suite of thyroid hormones and cortisol were measured in Australian fur seal pups in order to determine baseline concentrations as well as to describe their endocrinology over this critical developmental period. A cross-section of newborn pups from a breeding colony located on Kanowna Island, Australia were sampled at six different times over the course of the 10 month lactation period. Sample times were designed to correspond to periods of heightened physiological change during pre-weaning development: post-natal, pre-molt, the initiation of molt, mid-molt, period of peak milk intake and weaning. Results indicate that the greatest hormonal changes were associated with the post-natal stage and molt, with molt showing the greatest changes, as has been reported for several species of pinnipeds. Two forms of thyroid hormones analyzed (Total T(4), and Free T(3)), increased with the initiation of the molt, and Free T(3) exhibited a second increase that was associated with the period of peak milk intake. The T(3):T(4) ratio was significantly lower during the initiation of molt than either pre- or mid-molt. The study was able to describe physiological change during the first year of life in Australian fur seals as well as document basal concentrations of thyroid hormones and cortisol in pups of this species.
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Strong PCR, Hinchliffe SJ, Patrick H, Atkinson S, Champion OL, Wren BW. Identification and characterisation of a novel adhesin Ifp in Yersinia pseudotuberculosis. BMC Microbiol 2011; 11:85. [PMID: 21527009 PMCID: PMC3102037 DOI: 10.1186/1471-2180-11-85] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2011] [Accepted: 04/28/2011] [Indexed: 11/23/2022] Open
Abstract
Background In order to identify new virulence determinants in Y. pseudotuberculosis a comparison between its genome and that of Yersinia pestis was undertaken. This reveals dozens of pseudogenes in Y. pestis, which are still putatively functional in Y. pseudotuberculosis and may be important in the enteric lifestyle. One such gene, YPTB1572 in the Y. pseudotuberculosis IP32953 genome sequence, encodes a protein with similarity to invasin, a classic adhesion/invasion protein, and to intimin, the attaching and effacing protein from enteropathogenic (EPEC) and enterohaemorraghic (EHEC) Escherichia coli. Results We termed YPTB1572 Ifp (Intimin family protein) and show that it is able to bind directly to human HEp-2 epithelial cells. Cysteine and tryptophan residues in the C-terminal region of intimin that are essential for function in EPEC and EHEC are conserved in Ifp. Protein binding occurred at distinct foci on the HEp-2 cell surface and can be disrupted by mutation of a single cysteine residue at the C-terminus of the protein. Temporal expression analysis using lux reporter constructs revealed that ifp is expressed at late log phase at 37°C in contrast to invasin, suggesting that Ifp is a late stage adhesin. An ifp defined mutant showed a reduction in adhesion to HEp-2 cells and was attenuated in the Galleria mellonella infection model. Conclusion A new Y. pseudotuberculosis adhesin has been identified and characterised. This Ifp is a new member in the family of invasin/intimin outer membrane adhesins.
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Chan KG, Atkinson S, Mathee K, Sam CK, Chhabra SR, Cámara M, Koh CL, Williams P. Characterization of N-acylhomoserine lactone-degrading bacteria associated with the Zingiber officinale (ginger) rhizosphere: co-existence of quorum quenching and quorum sensing in Acinetobacter and Burkholderia. BMC Microbiol 2011; 11:51. [PMID: 21385437 PMCID: PMC3062576 DOI: 10.1186/1471-2180-11-51] [Citation(s) in RCA: 126] [Impact Index Per Article: 9.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/31/2010] [Accepted: 03/08/2011] [Indexed: 11/30/2022] Open
Abstract
BACKGROUND Cell-to-cell communication (quorum sensing (QS)) co-ordinates bacterial behaviour at a population level. Consequently the behaviour of a natural multi-species community is likely to depend at least in part on co-existing QS and quorum quenching (QQ) activities. Here we sought to discover novel N-acylhomoserine lactone (AHL)-dependent QS and QQ strains by investigating a bacterial community associated with the rhizosphere of ginger (Zingiber officinale) growing in the Malaysian rainforest. RESULTS By using a basal growth medium containing N-(3-oxohexanoyl)homoserine lactone (3-oxo-C6-HSL) as the sole source of carbon and nitrogen, the ginger rhizosphere associated bacteria were enriched for strains with AHL-degrading capabilities. Three isolates belonging to the genera Acinetobacter (GG2), Burkholderia (GG4) and Klebsiella (Se14) were identified and selected for further study. Strains GG2 and Se14 exhibited the broadest spectrum of AHL-degrading activities via lactonolysis while GG4 reduced 3-oxo-AHLs to the corresponding 3-hydroxy compounds. In GG2 and GG4, QQ was found to co-exist with AHL-dependent QS and GG2 was shown to inactivate both self-generated and exogenously supplied AHLs. GG2, GG4 and Se14 were each able to attenuate virulence factor production in both human and plant pathogens. CONCLUSIONS Collectively our data show that ginger rhizosphere bacteria which make and degrade a wide range of AHLs are likely to play a collective role in determining the QS-dependent phenotype of a polymicrobial community.
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Hothersall J, Murphy AC, Iqbal Z, Campbell G, Stephens ER, Wu J, Cooper H, Atkinson S, Williams P, Crosby J, Willis CL, Cox RJ, Simpson TJ, Thomas CM. Manipulation of quorum sensing regulation in Pseudomonas fluorescens NCIMB 10586 to increase mupirocin production. Appl Microbiol Biotechnol 2011; 90:1017-26. [PMID: 21318358 DOI: 10.1007/s00253-011-3145-2] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2010] [Revised: 01/18/2011] [Accepted: 01/21/2011] [Indexed: 11/28/2022]
Abstract
Transcription of the 74 kb Pseudomonas fluorescens mupirocin [pseudomonic acid (PA)] biosynthesis cluster depends on quorum sensing-dependent regulation via the LuxI/LuxR homologues MupI/MupR. To facilitate analysis of novel PAs from pathway mutants, we investigated factors that affect mup gene expression. First, the signal produced by MupI was identified as N-(3-oxodecanoyl)homoserine lactone, but exogenous addition of this molecule did not activate mupirocin production prematurely nor did expression of mupI in trans increase metabolite production. Second, we confirmed that mupX, encoding an amidase/hydrolase that can degrade N-acylhomoserine lactones, is also required for efficient expression, consistent with its occurrence in a regulatory module linked to unrelated genes in P. fluorescens. Third, and most significantly, mupR expression in trans to wild type and mutants can increase production of antibiotic and novel intermediates up to 17-fold.
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Czajkowski R, Krzyżanowska D, Karczewska J, Atkinson S, Przysowa J, Lojkowska E, Williams P, Jafra S. Inactivation of AHLs by Ochrobactrum sp. A44 depends on the activity of a novel class of AHL acylase. ENVIRONMENTAL MICROBIOLOGY REPORTS 2011; 3:59-68. [PMID: 23761232 DOI: 10.1111/j.1758-2229.2010.00188.x] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/02/2023]
Abstract
The soil isolate Ochrobactrum sp. A44 inactivates N-acyl homoserine lactone (AHL) quorum sensing signal molecules and is capable of quenching the AHL-dependent virulence of Pectobacterium carotovorum in planta. To characterize this AHL inactivating activity, Ochrobactrum cell extracts were prepared and their capacity to degrade a broad range of AHLs was determined. AHLs with acyl chains ranging from C4 to C14 with or without 3-oxo or 3-hydroxy substituents were all inactivated to varying extents; long chain AHLs were generally more susceptible than short chain compounds irrespective of the three position substituent. HPLC and LC-tandem mass spectrometry of the AHL degradation products revealed that the AHL inactivating activity present in the Ochrobactrum cell extract cleaved the AHL amide bond. To identify the gene(s) responsible for AHL degradation, Ochrobactrum sp. A44 was subjected to random transposon (Tn) mutagenesis and the resulting mutants screened for the loss of AHL acylase activity. The Tn insertion in mutant A6731 was mapped to a gene termed aiiO, the translated product of which belongs to the α/β hydrolase superfamily which constitutes a novel type of AHL acylase.
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Haber MM, Hunt B, Freston JW, Peura DA, Kovacs TO, Atkinson S, Hisada M. Changes of gastric histology in patients with erosive oesophagitis receiving long-term lansoprazole maintenance therapy. Aliment Pharmacol Ther 2010; 32:83-96. [PMID: 20345509 DOI: 10.1111/j.1365-2036.2010.04310.x] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
BACKGROUND Changes in gastric histology associated with long-term maintenance therapy with lansoprazole for erosive oesophagitis have not been well described. AIM To evaluate the effect on gastric histology of long-term dose-titrated lansoprazole administered as maintenance therapy for up to 82 months in patients with erosive oesophagitis. METHODS Sequential gastric biopsy specimens were obtained for evaluation of histological changes and Helicobacter pylori infection status. RESULTS Active and chronic inflammation improved from baseline to final visit in a majority of patients receiving long-term therapy with lansoprazole, irrespective of baseline H. pylori infection status. Reductions in active inflammation in the gastric body and antrum were seen in 53% (17/32) and 67% (20/30) of H. pylori-positive patients, respectively, and in 88% (7/8) and 86% (12/14) of H. pylori-negative patients, respectively. Reductions in chronic inflammation in the gastric body and antrum were seen in 38% (12/32) and 47% (15/32) of H. pylori-positive patients, respectively, and in 58% (70/121) and 57% (68/120) of H. pylori-negative patients, respectively. No clinically meaningful increases in hyperplasia, dysplasia, neoplasia, intestinal metaplasia or atrophy were observed during the follow-up period. CONCLUSIONS Lansoprazole administered as maintenance therapy for up to 6 years in patients with erosive oesophagitis demonstrated gastric mucosal safety and was well tolerated.
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Liu X, Jia J, Atkinson S, Cámara M, Gao K, Li H, Cao J. Biocontrol potential of an endophytic Serratia sp. G3 and its mode of action. World J Microbiol Biotechnol 2010. [DOI: 10.1007/s11274-010-0321-y] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
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Atkinson S, Williams P. Quorum sensing and social networking in the microbial world. J R Soc Interface 2009; 6:959-78. [PMID: 19674996 PMCID: PMC2827448 DOI: 10.1098/rsif.2009.0203] [Citation(s) in RCA: 247] [Impact Index Per Article: 16.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2009] [Accepted: 07/10/2009] [Indexed: 12/15/2022] Open
Abstract
For many years, bacterial cells were considered primarily as selfish individuals, but, in recent years, it has become evident that, far from operating in isolation, they coordinate collective behaviour in response to environmental challenges using sophisticated intercellular communication networks. Cell-to-cell communication between bacteria is mediated by small diffusible signal molecules that trigger changes in gene expression in response to fluctuations in population density. This process, generally referred to as quorum sensing (QS), controls diverse phenotypes in numerous Gram-positive and Gram-negative bacteria. Recent advances have revealed that bacteria are not limited to communication within their own species but are capable of 'listening in' and 'broadcasting to' unrelated species to intercept messages and coerce cohabitants into behavioural modifications, either for the good of the population or for the benefit of one species over another. It is also evident that QS is not limited to the bacterial kingdom. The study of two-way intercellular signalling networks between bacteria and both uni- and multicellular eukaryotes as well as between eukaryotes is just beginning to unveil a rich diversity of communication pathways.
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Hu Y, Wang Y, Ding L, Lu P, Atkinson S, Chen S. Positive regulation of flhDC expression by OmpR in Yersinia pseudotuberculosis. Microbiology (Reading) 2009; 155:3622-3631. [DOI: 10.1099/mic.0.030908-0] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
OmpR has been demonstrated to negatively regulate the expression of the flagellar master operon flhDC in a wide variety of bacterial species. Here we report the positive regulation of flhDC expression by OmpR in Yersinia pseudotuberculosis. A σ
70-dependent promoter was identified by primer extension analysis and an active region with two conserved OmpR-binding sites around the flhDC promoter was confirmed. To confirm the regulation of flhDC expression by OmpR, flhDC as well as the downstream flagellar genes fliA, flgD, flgA, flgM, fliC and flaA were fused to lacZ, and decreased expression of all these genes in an ompR mutant (ΔompR) was detected. Furthermore, ΔompR was defective in bacterial motility and flagella synthesis. This defect was due to the low level of expression of flhDC in ΔompR since overproduction of FlhDC in ΔompR restored bacterial motility. The importance of two conserved OmpR-binding sites around the flhDC promoter region in the regulation of flhDC expression by OmpR was demonstrated by the fact that mutation of either one or both sites significantly decreased the promoter activity in the wild-type but not in ΔompR. The binding of OmpR to these two sites was also demonstrated by DNA mobility shift assay. The possible mechanism underlying this positive regulation in Y. pseudotuberculosis is discussed. To our knowledge, this is the first report to demonstrate that OmpR positively regulates flhDC expression.
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Villegas-Amtmann S, Atkinson S, Costa DP. Low Synchrony in the Breeding Cycle of Galapagos Sea Lions Revealed by Seasonal Progesterone Concentrations. J Mammal 2009. [DOI: 10.1644/08-mamm-a-319.1] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022] Open
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Matutes E, Parry-Jones N, Brito-Babapulle V, Wotherspoon A, Morilla R, Atkinson S, Elnenaei MO, Jain P, Giustolisi GM, A'Hern RP, Catovsky D. The Leukemic Presentation of Mantle-cell Lymphoma: Disease Features and Prognostic Factors in 58 Patients. Leuk Lymphoma 2009; 45:2007-15. [PMID: 15370245 DOI: 10.1080/10428190410001723331] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
Abstract
Mantle-cell lymphoma (MCL) is a B-cell malignancy with distinct molecular genetics and pathological features. Peripheral blood involvement has been reported with variable frequency, but information on the natural history of cases presenting with leukemia is lacking. This study aimed to determine the clinical and prognostic features of such cases. We studied clinical features, tumor characteristics, prognostic factors and outcome in 58 patients with leukemic presentation of MCL. Diagnosis was based on morphology, immunophenotype, presence of t(11;14), histology and cyclin D1 expression. The median age was 62 years and male:female 2.4:1. Presenting features included splenomegaly (74%), lymphadenopathy (45%), hepatomegaly (17%) and, in a minority, gastro-intestinal involvement or involvement of Waldeyer's ring; 10% had lymphocytosis alone. Six patients developed central nervous system disease. Median lymphocyte count was 58 x 10(9)/l, 55% had anemia and 17% had thrombocytopenia. Morphology of peripheral blood showed small-cell MCL in 15% of cases, typical MCL in 46% and blastoid MCL in 39%. Immunological markers showed a typical phenotype (CD5+ CD23 -) in 68%, and atypical phenotypes, CD5- CD23- in 17% or CD5+ CD23+ in 15%. CLL scores were 0, 1 or 2 in 96%. Median overall survival was 36 months. Good response to first-line treatment (P = 0.0008) and splenomegaly (P = 0.03) were favorable prognostic factors, while other features including morphology and CD38 expression had no impact on survival or treatment response. This analysis demonstrates that except for splenomegaly, survival of MCL patients presenting with leukemia is not significantly influenced by clinical or tumor characteristics. Splenectomy is a useful treatment option in this group of patients.
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Govindarajan A, Atkinson S. Combined spinal epidural anaesthesia for ex utero intrapartum treatment (EXIT) procedure. Anaesthesia 2009. [DOI: 10.1111/j.1365-2044.2009.05966_11.x] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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Freston JW, Hisada M, Peura DA, Haber MM, Kovacs TO, Atkinson S, Hunt B. The clinical safety of long-term lansoprazole for the maintenance of healed erosive oesophagitis. Aliment Pharmacol Ther 2009; 29:1249-60. [PMID: 19416133 DOI: 10.1111/j.1365-2036.2009.03998.x] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
BACKGROUND The clinical safety of long-term lansoprazole therapy for the maintenance of healed erosive oesophagitis has not been extensively studied in clinical trials. AIM To assess the long-term clinical safety of dose-titrated lansoprazole as maintenance therapy for up to 82 months in subjects with healed erosive oesophagitis. METHODS Clinical safety was assessed by monitoring adverse events (AEs), laboratory data including serum gastrin levels, and endoscopy. RESULTS Mean duration (+/- s.d.) of lansoprazole treatment during the titrated open-label period was 56 +/- 24 months (range <1-82 months). Overall, 189 of 195 (97%) subjects experienced a total of 2825 treatment-emergent AEs. Most AEs occurred during the first year of treatment, were mild-to-moderate in severity and resolved while on treatment. Of 155 serious AEs (in 74 subjects), only two (colitis and rectal haemorrhage in one subject) were considered treatment-related. Sixty-nine of 195 subjects (35%) experienced 187 treatment-related AEs, with diarrhoea (10%), headache (8%) and abdominal pain (6%) being the most common. Gastrin levels > or = 400 pg/mL were seen in 9% of subjects; hypergastrinemia was not associated with gastro-intestinal AEs or nodules/polyps. CONCLUSIONS Lansoprazole maintenance therapy for up to 6 years is safe and well tolerated in subjects with healed erosive oesophagitis.
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Ding L, Wang Y, Hu Y, Atkinson S, Williams P, Chen S. Functional characterization of FlgM in the regulation of flagellar synthesis and motility in Yersinia pseudotuberculosis. Microbiology (Reading) 2009; 155:1890-1900. [DOI: 10.1099/mic.0.026294-0] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
We describe here the functional characterization of the flgM gene in Yersinia pseudotuberculosis. Direct interaction of FlgM with the alternative sigma factor σ
28 (FliA) was first confirmed. A conserved region in the C-terminus of FlgM was found which included the σ
28 binding domain. By site-directed mutagenesis, bacterial two-hybrid analysis and Western blotting, the primary FlgM binding sites with σ
28 were shown to be Ile85, Ala86 and Leu89. A role for FlgM in swimming motility was demonstrated by inactivation of flgM and subsequent complementation in trans. Transcriptional fusion analyses showed differential gene expression of flhDC, fliA, flgM and fliC in the fliA and flgM mutants compared with the wild-type. flhDC expression was not influenced by σ
28 or FlgM while fliA expression was abolished in the fliA mutant and considerably reduced in the flgM mutant when compared to the wild-type, indicating that both FliA and FlgM can activate fliA transcription. Conversely, flgM transcription was higher in the fliA mutant when compared to the wild-type, suggesting that flgM transcription was repressed by σ
28. Interestingly, fliC expression was markedly increased in the flgM mutant, suggesting a negative regulatory role for FlgM in fliC expression. The transcription of other σ-dependent genes (cheW, flgD, flaA, csrA and fliZ) was also examined in fliA and flgM mutant backgrounds and this revealed that other σ-factors apart from σ
28 may be involved in flagellar biogenesis in Y. pseudotuberculosis. Taking together the motility phenotypes and effects of flgM mutation on the regulation of these key motility genes, we propose that the mechanisms regulating flagellar biogenesis in Y. pseudotuberculosis may differ from those described for other bacteria.
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Hu Y, Lu P, Wang Y, Ding L, Atkinson S, Chen S. OmpR positively regulates urease expression to enhance acid survival of Yersinia pseudotuberculosis. MICROBIOLOGY-SGM 2009; 155:2522-2531. [PMID: 19443542 DOI: 10.1099/mic.0.028381-0] [Citation(s) in RCA: 57] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
Yersinia pseudotuberculosis is an enteric bacterium which must overcome the acidic stress in host organs for successful colonization, but how this bacterium survives in acidic conditions remains largely unknown. In the present study, the importance of OmpR in acid survival of Y. pseudotuberculosis YpIII was confirmed by the fact that mutation of ompR (strain DeltaompR) greatly reduced cell survival at pH 4.5 or lower. To characterize the regulatory role of OmpR in this acid survival process, proteomic analysis was carried out to compare YpIII at pH 7.0 and pH 4.5 with DeltaompR at pH 7.0, and urease components were revealed to be the main targets for OmpR regulation. Addition of urea to the culture medium also enhanced acid survival of YpIII but not DeltaompR and urease activity was significantly induced by acid in YpIII but not in DeltaompR. Each of the seven components of the YpIII urease gene cluster was fused to a lacZ reporter and their expression was dramatically decreased in a DeltaompR background; this supports the notion that OmpR positively regulates urease expression. Furthermore, gel shift analysis revealed that OmpR binds to the deduced promoter regions of three polycistronic transcriptional units (ureABC, ureEF and ureGD) in the urease cluster, suggesting that the regulation of OmpR to urease components is direct. Taken together, these data strongly suggest that OmpR activates urease expression to enhance acid survival in Y. pseudotuberculosis.
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Tait K, Williamson H, Atkinson S, Williams P, Cámara M, Joint I. Turnover of quorum sensing signal molecules modulates cross-kingdom signalling. Environ Microbiol 2009; 11:1792-802. [PMID: 19508552 DOI: 10.1111/j.1462-2920.2009.01904.x] [Citation(s) in RCA: 76] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
N-acylhomoserine lactone (AHL) quorum-sensing molecules modulate the swimming behaviour of zoospores of the macroalga Ulva to facilitate the location of bacterial biofilms. Here we show that the intertidal surfaces colonized by Ulva are dominated by Alphaproteobacteria, particularly the Rhodobacteraceae family, and the Bacteroidetes family Flavobacteriaceae, and that this diverse assemblage both produces and degrades AHLs. N-acylhomoserine lactones could also be extracted from the surfaces of pebbles recovered from intertidal rock-pools. Bacteria representative of this assemblage were isolated and tested for the production and degradation of AHLs, and for their ability to modulate zoospore settlement at different biofilm densities. Of particular interest was a Shewanella sp. This strain produced three major AHLs (OC4, OC10 and OC12) in the late exponential phase, but the longer-chain AHLs were rapidly degraded in the stationary phase. Degradation occurred via both lactonase and amidase activity. A close relationship was found between AHL synthesis and Ulva zoospore settlement. The Shewanella isolate also interfered with AHL production by a Sulfitobacter isolate and its ability to enhance zoospore settlement in a polymicrobial biofilm. This influence on the attachment of Ulva zoospores suggests that AHL-degrading strains can affect bacterial community behaviour by interfering with quorum sensing between neighbouring bacteria. More importantly, these interactions may exert wider ecological effects across different kingdoms.
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Neganova I, Zhang X, Atkinson S, Lako M. Expression and functional analysis of G1 to S regulatory components reveals an important role for CDK2 in cell cycle regulation in human embryonic stem cells. Oncogene 2008; 28:20-30. [PMID: 18806832 DOI: 10.1038/onc.2008.358] [Citation(s) in RCA: 140] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
One of the characteristic features of human embryonic stem cells (hESCs) is the competence for self-renewal and pluripotency. To date, little is known about cell cycle regulation in these cells and how the cell cycle machinery influences hESCs properties. A common feature of human, murine and primate ESCs is the presence of a short G1 phase, which has been viewed as a time window during which stem cells are exposed to differentiation signals. We used the hESCs differentiation model and comparisons to human embryonic carcinoma (EC) cells to study the key regulators of G1 to S transition in hESCs. Our studies show that hESCs express all G1-specific CYCLINs (D1, D2, D3 and E) and cyclin-dependent kinases (CDK) (CDK2, CDK4 and CDK6) at variable levels. In contrast to murine ESCs, most of the cell cycle regulators in hESCs show cell cycle-dependent expression, thus revealing important differences in the expression of cell cycle regulatory components between these two embryonic cell types. Knockdown of CDK2 using RNA interference resulted in hESCs arrest at G1 phase of the cell cycle and differentiation to extraembryonic lineages. This suggests an important role for CDK2 in cell cycle regulation in hESCs that are likely to bear significant impacts on the maintenance of their pluripotent phenotype.
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Govindarajan A, Shields M, Atkinson S. 795. Local Anaesthetic Allergy Testing in Pregnancy. Reg Anesth Pain Med 2008. [DOI: 10.1136/rapm-00115550-200809001-00283] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
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71
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Govindarajan A, Atkinson S. 792. Combined Spinal Epidural Anaesthesia for Ex Utero Intrapartum(exit) Procedure. Reg Anesth Pain Med 2008. [DOI: 10.1136/rapm-00115550-200809001-00257] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/04/2022]
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72
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Parker P, Harvey JT, Maniscalco JM, Atkinson S. Pupping-site fidelity among individual Steller sea lions (Eumetopias jubatus) at Chiswell Island, Alaska. CAN J ZOOL 2008. [DOI: 10.1139/z08-058] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Pupping-site fidelity (defined as pupping within 5.8 m of a previous location in ≥2 years) in Steller sea lions ( Eumetopias jubatus (Schreber, 1776)) was investigated during the breeding seasons from 2001 to 2005 at Chiswell Island, a small rookery in the Gulf of Alaska. Density of females was minimal with 54–80 pups born. Photo-identification of individuals and GPS points, including elevation of the rookery, were used to determine locations of 297 births. Sixty-four percentage (35/55) of the females exhibited pupping-site fidelity, and mean frequency of site fidelity was greater for females that gave birth >3 times. Fifty percentage of the births occurred at 22% of the locations for all years, indicating that multiple births occurred at some locations throughout the breeding season. Competition or aggression among females for specific pupping locations before birth was not observed, and there was no temporal order of pupping locations used, indicating that the rookery was not overcrowded and that many suitable pupping locations existed. Multiparous females gave birth at significantly greater distances from the surf zone than primiparous females. Long-term monitoring of pupping-site fidelity in combination with other measures of maternal care will ultimately determine which factors have the greatest effect on pup survival.
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Atkinson S, Chang CY, Patrick HL, Buckley CMF, Wang Y, Sockett RE, Cámara M, Williams P. Functional interplay between theYersinia pseudotuberculosisYpsRI and YtbRI quorum sensing systems modulates swimming motility by controlling expression offlhDCandfliA. Mol Microbiol 2008; 69:137-51. [DOI: 10.1111/j.1365-2958.2008.06268.x] [Citation(s) in RCA: 48] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
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Sunguya BFP, Koola JI, Atkinson S. Infections associated with severe malnutrition among hospitalised children in East Africa. ACTA ACUST UNITED AC 2008; 8:189-92. [PMID: 18254514 DOI: 10.4314/thrb.v8i3.45120] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
Severe protein-energy malnutrition (PEM) predisposes affected children to various infections, which either worsens their nutritional status or causes malnutrition, hence complicating their management and outcome. This study was carried out to determine the infections associated with severe malnutrition among children admitted at Kilifi District Hospital (KDH) in Kenya and Muhimbili National Hospital (MNH) in Dar es Salaam, Tanzania. Data was collected from hospital register books and online system database. A total of 1121 children with severe malnutrition were admitted during a period of one year (2004-2005) (MNH = 781; KDH = 340). The proportion of male children with malnutrition was higher than that of female children. Non-oedematous malnutrition was more prevalent at MNH (N = 504; 64%) than KDH (N = 130; 38%). Conversely, oedematous was more prevalence than non-oedematous malnutrition among children admitted at KDH (N = 2 10; 61.7%). More than 75% of all patients with severe PEM were children < 2 years old. Thirty-six per cent of all severe PEM cases had malaria in both hospitals. Forty-five per cent of all admitted patients with severe PEM at KDH had diarrhoea. Two hundred twenty two (28%) and 64 (19%) of the children with severe malnutrition died at MNH and KDH, respectively. Oedematous PEM was associated with a higher case fatality rate than non-oedematous one (P < 0.05). At MNH, 86% of the patients who died with severe malnutrition had other co-morbidities. More (46%) oedematous malnourished patients with co-infections died at MNH than non-oedematous malnourished patients (19%). At KDH, septicaemia was the leading cause of death (55%) among severely malnourished patients. In conclusion, coinfections complicate the management of severe malnutrition and are associated with higher death rate. Management of such infections is of paramount importance to reduce case fatality rates.
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Sala A, Talsma D, Webber C, Posgate S, Atkinson S, Barr R. Bone mineral status after treatment of malignant lymphoma in childhood and adolescence. Eur J Cancer Care (Engl) 2007; 16:373-9. [PMID: 17587363 DOI: 10.1111/j.1365-2354.2006.00757.x] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
The relationship between bone mineral mass and cumulative dose of corticosteroids (CDC) was investigated in 42 children and adolescents treated for Hodgkin disease (HD; n = 22) and non-Hodgkin lymphoma (NHL; n = 20). The median age at the time of the study was 24.1 years for HD survivors and 14.1 years for NHL survivors. Dual-energy X-ray absorptiometry [bone mineral density of the lumbar spine (LS-BMD) expressed as Z-scores] and peripheral quantitative computed tomography at the distal radius [trabecular volumetric BMD (vBMD-trab)] were undertaken. Osteopenia (Z-score < -1.00) was found in 9/22 patients with HD and 10/20 with NHL, while 34% (HD = 6, NHL = 8) had a vBMD-trab below the normal range. The CDC correlated inversely with LS-BMD Z-score (r =-0.41, P = 0.007). There was a statistically significantly higher vBMD-trab in patients who received low (1-4 g/m(2)) compared with high (>or=20 g/m(2)) CDC (P = 0.031). Treatment of malignant lymphoma with high CDC is a risk factor for development of osteopenia.
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