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Kirioukhova O, Shah JN, Larsen DS, Tayyab M, Mueller NE, Govind G, Baroux C, Federer M, Gheyselinck J, Barrell PJ, Ma H, Sprunck S, Huettel B, Wallace H, Grossniklaus U, Johnston AJ. Aberrant imprinting may underlie evolution of parthenogenesis. Sci Rep 2018; 8:10626. [PMID: 30006526 PMCID: PMC6045609 DOI: 10.1038/s41598-018-27863-7] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2017] [Accepted: 05/11/2018] [Indexed: 01/10/2023] Open
Abstract
Genomic imprinting confers parent-of-origin-specific gene expression, thus non-equivalent and complementary function of parental genomes. As a consequence, genomic imprinting poses an epigenetic barrier to parthenogenesis in sexual organisms. We report aberrant imprinting in Boechera, a genus in which apomicts evolved from sexuals multiple times. Maternal activation of a MADS-box gene, a homolog of which is imprinted and paternally expressed in the sexual relative Arabidopsis, is accompanied by locus-specific DNA methylation changes in apomicts where parental imprinting seems to be relaxed.
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Affiliation(s)
- Olga Kirioukhova
- University of Heidelberg, Centre for Organismal Studies, Laboratory of Germline Genetics & Evo-Devo, Heidelberg, Germany.,Jacobs University, Life Sciences & Chemistry, Laboratory of Germline Genetics & Evo-Devo, Bremen, Germany
| | - Jubin N Shah
- University of Heidelberg, Centre for Organismal Studies, Laboratory of Germline Genetics & Evo-Devo, Heidelberg, Germany
| | - Danaé S Larsen
- University of Heidelberg, Centre for Organismal Studies, Laboratory of Germline Genetics & Evo-Devo, Heidelberg, Germany
| | - Muhammad Tayyab
- University of Heidelberg, Centre for Organismal Studies, Laboratory of Germline Genetics & Evo-Devo, Heidelberg, Germany
| | - Nora E Mueller
- University of Heidelberg, Centre for Organismal Studies, Laboratory of Germline Genetics & Evo-Devo, Heidelberg, Germany
| | - Geetha Govind
- University of Heidelberg, Centre for Organismal Studies, Laboratory of Germline Genetics & Evo-Devo, Heidelberg, Germany.,University of Agricultural Sciences, College of Agriculture Sciences, Department of crop physiology, Hassan, India
| | - Célia Baroux
- University of Zurich, Department of Plant and Microbial Biology and Zurich-Basel Plant Science Center, Zurich, Switzerland
| | - Michael Federer
- University of Zurich, Department of Plant and Microbial Biology and Zurich-Basel Plant Science Center, Zurich, Switzerland
| | - Jacqueline Gheyselinck
- University of Zurich, Department of Plant and Microbial Biology and Zurich-Basel Plant Science Center, Zurich, Switzerland
| | - Philippa J Barrell
- University of Zurich, Department of Plant and Microbial Biology and Zurich-Basel Plant Science Center, Zurich, Switzerland.,New Zealand Institute for Plant and Food Research, Christchurch, New Zealand
| | - Hong Ma
- University of Zurich, Department of Plant and Microbial Biology and Zurich-Basel Plant Science Center, Zurich, Switzerland.,The Pennsylvania State University, the Huck Institute of Life Sciences, Department of Biology, The University Park, Pennsylvania, USA.,Fudan University, State Key Laboratory of Genetic Engineering, Institute of Plant Biology, School of Life Sciences, Fudan University, Shanghai, China
| | - Stefanie Sprunck
- University of Regensburg, Cell Biology and Plant Biochemistry, Regensburg, Germany
| | - Bruno Huettel
- Max-Planck-Institute for Plant Breeding, Cologne, Germany
| | - Helen Wallace
- University of the Sunshine Coast, Faculty of Science, Health, Education and Engineering, Genecology Research Centre, Maroochydore, Australia
| | - Ueli Grossniklaus
- University of Zurich, Department of Plant and Microbial Biology and Zurich-Basel Plant Science Center, Zurich, Switzerland.
| | - Amal J Johnston
- University of Heidelberg, Centre for Organismal Studies, Laboratory of Germline Genetics & Evo-Devo, Heidelberg, Germany. .,Jacobs University, Life Sciences & Chemistry, Laboratory of Germline Genetics & Evo-Devo, Bremen, Germany. .,University of Zurich, Department of Plant and Microbial Biology and Zurich-Basel Plant Science Center, Zurich, Switzerland. .,ETH Zurich, Department of Biology and Zurich-Basel Plant Science Center, Zurich, Switzerland.
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Kirioukhova O, Shah JN, Larsen DS, Tayyab M, Mueller NE, Govind G, Baroux C, Federer M, Gheyselinck J, Barrell PJ, Ma H, Sprunck S, Huettel B, Wallace H, Grossniklaus U, Johnston AJ. Aberrant imprinting may underlie evolution of parthenogenesis. Sci Rep 2018. [PMID: 30006526 DOI: 10.1038/s41598-018-27863-27867] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/28/2023] Open
Abstract
Genomic imprinting confers parent-of-origin-specific gene expression, thus non-equivalent and complementary function of parental genomes. As a consequence, genomic imprinting poses an epigenetic barrier to parthenogenesis in sexual organisms. We report aberrant imprinting in Boechera, a genus in which apomicts evolved from sexuals multiple times. Maternal activation of a MADS-box gene, a homolog of which is imprinted and paternally expressed in the sexual relative Arabidopsis, is accompanied by locus-specific DNA methylation changes in apomicts where parental imprinting seems to be relaxed.
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Affiliation(s)
- Olga Kirioukhova
- University of Heidelberg, Centre for Organismal Studies, Laboratory of Germline Genetics & Evo-Devo, Heidelberg, Germany
- Jacobs University, Life Sciences & Chemistry, Laboratory of Germline Genetics & Evo-Devo, Bremen, Germany
| | - Jubin N Shah
- University of Heidelberg, Centre for Organismal Studies, Laboratory of Germline Genetics & Evo-Devo, Heidelberg, Germany
| | - Danaé S Larsen
- University of Heidelberg, Centre for Organismal Studies, Laboratory of Germline Genetics & Evo-Devo, Heidelberg, Germany
| | - Muhammad Tayyab
- University of Heidelberg, Centre for Organismal Studies, Laboratory of Germline Genetics & Evo-Devo, Heidelberg, Germany
| | - Nora E Mueller
- University of Heidelberg, Centre for Organismal Studies, Laboratory of Germline Genetics & Evo-Devo, Heidelberg, Germany
| | - Geetha Govind
- University of Heidelberg, Centre for Organismal Studies, Laboratory of Germline Genetics & Evo-Devo, Heidelberg, Germany
- University of Agricultural Sciences, College of Agriculture Sciences, Department of crop physiology, Hassan, India
| | - Célia Baroux
- University of Zurich, Department of Plant and Microbial Biology and Zurich-Basel Plant Science Center, Zurich, Switzerland
| | - Michael Federer
- University of Zurich, Department of Plant and Microbial Biology and Zurich-Basel Plant Science Center, Zurich, Switzerland
| | - Jacqueline Gheyselinck
- University of Zurich, Department of Plant and Microbial Biology and Zurich-Basel Plant Science Center, Zurich, Switzerland
| | - Philippa J Barrell
- University of Zurich, Department of Plant and Microbial Biology and Zurich-Basel Plant Science Center, Zurich, Switzerland
- New Zealand Institute for Plant and Food Research, Christchurch, New Zealand
| | - Hong Ma
- University of Zurich, Department of Plant and Microbial Biology and Zurich-Basel Plant Science Center, Zurich, Switzerland
- The Pennsylvania State University, the Huck Institute of Life Sciences, Department of Biology, The University Park, Pennsylvania, USA
- Fudan University, State Key Laboratory of Genetic Engineering, Institute of Plant Biology, School of Life Sciences, Fudan University, Shanghai, China
| | - Stefanie Sprunck
- University of Regensburg, Cell Biology and Plant Biochemistry, Regensburg, Germany
| | - Bruno Huettel
- Max-Planck-Institute for Plant Breeding, Cologne, Germany
| | - Helen Wallace
- University of the Sunshine Coast, Faculty of Science, Health, Education and Engineering, Genecology Research Centre, Maroochydore, Australia
| | - Ueli Grossniklaus
- University of Zurich, Department of Plant and Microbial Biology and Zurich-Basel Plant Science Center, Zurich, Switzerland.
| | - Amal J Johnston
- University of Heidelberg, Centre for Organismal Studies, Laboratory of Germline Genetics & Evo-Devo, Heidelberg, Germany.
- Jacobs University, Life Sciences & Chemistry, Laboratory of Germline Genetics & Evo-Devo, Bremen, Germany.
- University of Zurich, Department of Plant and Microbial Biology and Zurich-Basel Plant Science Center, Zurich, Switzerland.
- ETH Zurich, Department of Biology and Zurich-Basel Plant Science Center, Zurich, Switzerland.
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Bodenham Chair A, Babu S, Bennett J, Binks R, Fee P, Fox B, Johnston AJ, Klein AA, Langton JA, Mclure H, Tighe SQM. Association of Anaesthetists of Great Britain and Ireland: Safe vascular access 2016. Anaesthesia 2016; 71:573-85. [PMID: 26888253 PMCID: PMC5067617 DOI: 10.1111/anae.13360] [Citation(s) in RCA: 168] [Impact Index Per Article: 21.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 09/05/2015] [Indexed: 12/13/2022]
Abstract
Safe vascular access is integral to anaesthetic and critical care practice, but procedures are a frequent source of patient adverse events. Ensuring safe and effective approaches to vascular catheter insertion should be a priority for all practitioners. New technology such as ultrasound and other imaging has increased the number of tools available. This guidance was created using review of current practice and literature, as well as expert opinion. The result is a consensus document which provides practical advice on the safe insertion and removal of vascular access devices.
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Affiliation(s)
- A Bodenham Chair
- Anaesthesia and Intensive Care, Leeds Teaching Hospitals, Leeds, UK
| | - S Babu
- Anaesthesia, North Manchester General Hospital, Manchester, UK
| | - J Bennett
- Anaesthesia, Birmingham Children's Hospital, Birminham, UK
| | - R Binks
- Airedale Hospital and Faculty of Intensive Care Medicine, West Yorkshire, UK
| | - P Fee
- Anaesthesia, Belfast Health and Social Care Trust, Belfast, UK
| | - B Fox
- Anaesthesia, East Anglia, and Group of Anaesthetists in Training, AAGBI, London, UK
| | - A J Johnston
- Anaesthesia and Intensive Care, Addenbrooke's Hospital, Cambridge, UK
| | - A A Klein
- Anaesthesia, Papworth Hospital, Cambridge, UK
| | - J A Langton
- Anaesthesia, Plymouth Hospitals, Plymouth, and Royal College of Anaesthetists, UK
| | - H Mclure
- Anaesthesia, Leeds Teaching Hospitals, Leeds, UK
| | - S Q M Tighe
- Anaesthesia and Intensive Care, Countess of Chester Hospital and AAGBI Council, Chester, UK
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Shah JN, Kirioukhova O, Pawar P, Tayyab M, Mateo JL, Johnston AJ. Depletion of Key Meiotic Genes and Transcriptome-Wide Abiotic Stress Reprogramming Mark Early Preparatory Events Ahead of Apomeiotic Transition. Front Plant Sci 2016; 7:1539. [PMID: 27833618 PMCID: PMC5080521 DOI: 10.3389/fpls.2016.01539] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/02/2016] [Accepted: 09/30/2016] [Indexed: 05/19/2023]
Abstract
Molecular dissection of apomixis - an asexual reproductive mode - is anticipated to solve the enigma of loss of meiotic sex, and to help fixing elite agronomic traits. The Brassicaceae genus Boechera comprises of both sexual and apomictic species, permitting comparative analyses of meiotic circumvention (apomeiosis) and parthenogenesis. Whereas previous studies reported local transcriptome changes during these events, it remained unclear whether global changes associated with hybridization, polyploidy and environmental adaptation that arose during evolution of Boechera might serve as (epi)genetic regulators of early development prior apomictic initiation. To identify these signatures during vegetative stages, we compared seedling RNA-seq transcriptomes of an obligate triploid apomict and a diploid sexual, both isolated from a drought-prone habitat. Uncovered were several genes differentially expressed between sexual and apomictic seedlings, including homologs of meiotic genes ASYNAPTIC 1 (ASY1) and MULTIPOLAR SPINDLE 1 (MPS1) that were down-regulated in apomicts. An intriguing class of apomict-specific deregulated genes included several NAC transcription factors, homologs of which are known to be transcriptionally reprogrammed during abiotic stress in other plants. Deregulation of both meiotic and stress-response genes during seedling stages might possibly be important in preparation for meiotic circumvention, as similar transcriptional alteration was discernible in apomeiotic floral buds too. Furthermore, we noted that the apomict showed better tolerance to osmotic stress in vitro than the sexual, in conjunction with significant upregulation of a subset of NAC genes. In support of the current model that DNA methylation epigenetically regulates stress, ploidy, hybridization and apomixis, we noted that ASY1, MPS1 and NAC019 homologs were deregulated in Boechera seedlings upon DNA demethylation, and ASY1 in particular seems to be repressed by global DNA methylation exclusively in the apomicts. Variability in stress and transcriptional response in a diploid apomict, which is geographically distinct from the triploid apomict, pinpoints both common and independent features of apomixis evolution. Our study provides a molecular frame-work to investigate how the adaptive traits associated with the evolutionary history of apomicts co-adapted with meiotic gene deregulation at early developmental stage, in order to predate meiotic recombination, which otherwise is thought to be favorable in stress and low-fitness conditions.
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Affiliation(s)
- Jubin N. Shah
- Laboratory of Germline Genetics & Evo-Devo, Centre for Organismal Studies, University of HeidelbergHeidelberg, Germany
| | - Olga Kirioukhova
- Laboratory of Germline Genetics & Evo-Devo, Centre for Organismal Studies, University of HeidelbergHeidelberg, Germany
- Leibniz Institute of Plant Genetics and Crop Plant ResearchGatersleben, Germany
| | - Pallavi Pawar
- Laboratory of Germline Genetics & Evo-Devo, Centre for Organismal Studies, University of HeidelbergHeidelberg, Germany
| | - Muhammad Tayyab
- Laboratory of Germline Genetics & Evo-Devo, Centre for Organismal Studies, University of HeidelbergHeidelberg, Germany
| | - Juan L. Mateo
- Centre for Organismal Studies, University of HeidelbergHeidelberg, Germany
- *Correspondence: Amal J. Johnston, ; Juan L. Mateo,
| | - Amal J. Johnston
- Laboratory of Germline Genetics & Evo-Devo, Centre for Organismal Studies, University of HeidelbergHeidelberg, Germany
- Leibniz Institute of Plant Genetics and Crop Plant ResearchGatersleben, Germany
- *Correspondence: Amal J. Johnston, ; Juan L. Mateo,
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Bishop DC, Johnston AJ, Kwan JMW, Antonenas V, Gottlieb DJ. Haploidentical peripheral blood stem cell infusion in combination with chemotherapy for acute myeloid leukaemia in elderly patients. Intern Med J 2014; 44:1038-40. [PMID: 25302724 DOI: 10.1111/imj.12551] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2014] [Accepted: 06/22/2014] [Indexed: 11/29/2022]
Abstract
Elderly patients with acute myeloid leukaemia (AML) have a poor prognosis with standard chemotherapy. Two elderly AML patients treated with infusion of family-derived partially human leukocyte antigen (HLA)-matched peripheral blood stem cells following each cycle of chemotherapy entered morphological complete remission without graft versus host disease or major toxicity. Our results support this as a non-toxic approach for inducing a graft versus leukaemia effect in patients not suitable for allogeneic transplantation. Additional resources required for donor assessment and harvest may be reduced by using banked partially HLA-matched mononuclear cells from unrelated donors.
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Affiliation(s)
- D C Bishop
- Department of Haematology, Westmead Hospital, Sydney, New South Wales, Australia; Sydney Medical School, University of Sydney, Sydney, New South Wales, Australia
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Paterson AL, Johnston AJ, Kingston D, Mahroof R. Clinical and economic impact of a switch from high- to low-volume renal replacement therapy in patients with acute kidney injury. Anaesthesia 2014; 69:977-82. [PMID: 24888258 DOI: 10.1111/anae.12706] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 03/22/2014] [Indexed: 11/28/2022]
Abstract
High-intensity renal replacement therapy protocols in intensive care patients with acute kidney injury have failed to translate to improved patient outcomes when compared with lower-intensity protocols. This retrospective study explored the clinical and economic impacts of switching from a 30-35 ml.kg(-1) .h(-1) (high-volume) to a 20 ml.kg(-1) .h(-1) (low-volume) protocol. Patients (n = 366) admitted 12 months before (n = 187) and after (n = 179) the switch were included in the study. There was no difference in in-hospital mortality (77/187 (41%) vs 75/179 (42%), respectively, p = 0.92), intensive care unit mortality (55/187 (29%) vs 61/179 (34%), respectively, p = 0.40), duration of organ support or extent of renal recovery between the high- and low-volume cohorts. A 25% reduction in daily replacement fluid usage was observed, equating to a cost saving of over £27 000 per annum. In conclusion, a switch from high- to low-volume continuous haemodiafiltration had minimal effects on clinical outcomes and resulted in marked cost savings.
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Johnston AJ, Bishop SM, Martin L, See TC, Streater CT. Defining peripherally inserted central catheter tip position and an evaluation of insertions in one unit. Anaesthesia 2013; 68:484-91. [PMID: 23488895 DOI: 10.1111/anae.12188] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 01/12/2013] [Indexed: 11/28/2022]
Abstract
Peripherally inserted central catheters are increasingly used to provide access to the central venous circulation. They are commonly positioned 'blind' using a variety of anthropometric techniques and operator experience to direct insertion length. Malposition rates are poorly defined because of differing insertion techniques, difficulties defining anatomical tip position on chest radiographs, controversy over what constitutes an adequate catheter position and possible differences between patient groups. We have developed a reproducible method to define catheter positions on chest radiograph and have applied this in a retrospective analysis of 256 ICU and 243 non-ICU catheter insertions over a 6-month period. Two different definitions were used for adequate position. 'Blind' positioning of peripherally inserted central catheters was associated with a definition-dependent malposition rate of 42-76%. Malposition rates were significantly higher in ICU patients. Emerging technologies may assist in reducing these high rates.
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Affiliation(s)
- A J Johnston
- John Farman Intensive Care Unit, Cambridge University Hospitals NHS Foundation Trust, Cambridge, UK.
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Johnston AJ, Gruissem W. Gametophyte differentiation and imprinting control in plants: Crosstalk between RBR and chromatin. Commun Integr Biol 2011; 2:144-6. [PMID: 19704913 DOI: 10.4161/cib.8319] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2009] [Accepted: 02/17/2009] [Indexed: 12/29/2022] Open
Abstract
The Retinoblastoma (pRb) pathway has been implicated as a convergent regulatory unit in the control of cell cycle and disease. We have shown that a crosstalk between RETINOBLASTOMA RELATED (RBR), the Arabidopsis homologue of pRb, and the genes encoding proteins of the chromatin complexes involved in DNA or histone methylation, controls gametophytic and post-fertilization differentiation events and a subset of imprinting effects. We describe here a plausible model that incorporates several components of the plant Retinoblastoma pathway, thus offering a novel paradigm that merges the traditional cell cycle and the chromatin components in the control of cell differentiation and imprinting.
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Affiliation(s)
- Amal J Johnston
- Department of Biology; Plant Biotechnology; ETH Zurich; Zurich, Switzerland
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Kirioukhova O, Johnston AJ, Kleen D, Kägi C, Baskar R, Moore JM, Bäumlein H, Gross-Hardt R, Grossniklaus U. Female gametophytic cell specification and seed development require the function of the putative Arabidopsis INCENP ortholog WYRD. Development 2011; 138:3409-20. [PMID: 21752930 DOI: 10.1242/dev.060384] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
Abstract
In plants, gametes, along with accessory cells, are formed by the haploid gametophytes through a series of mitotic divisions, cell specification and differentiation events. How the cells in the female gametophyte of flowering plants differentiate into gametes (the egg and central cell) and accessory cells remains largely unknown. In a screen for mutations that affect egg cell differentiation in Arabidopsis, we identified the wyrd (wyr) mutant, which produces additional egg cells at the expense of the accessory synergids. WYR not only restricts gametic fate in the egg apparatus, but is also necessary for central cell differentiation. In addition, wyr mutants impair mitotic divisions in the male gametophyte and endosperm, and have a parental effect on embryo cytokinesis, consistent with a function of WYR in cell cycle regulation. WYR is upregulated in gametic cells and encodes a putative plant ortholog of the inner centromere protein (INCENP), which is implicated in the control of chromosome segregation and cytokinesis in yeast and animals. Our data reveal a novel developmental function of the conserved cell cycle-associated INCENP protein in plant reproduction, in particular in the regulation of egg and central cell fate and differentiation.
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Affiliation(s)
- Olga Kirioukhova
- Institute of Plant Biology and Zürich-Basel Plant Science Center, University of Zürich, Zürich, Switzerland
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Koszegi D, Johnston AJ, Rutten T, Czihal A, Altschmied L, Kumlehn J, Wüst SEJ, Kirioukhova O, Gheyselinck J, Grossniklaus U, Bäumlein H. Members of the RKD transcription factor family induce an egg cell-like gene expression program. Plant J 2011; 67:280-91. [PMID: 21457369 DOI: 10.1111/j.1365-313x.2011.04592.x] [Citation(s) in RCA: 81] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/18/2023]
Abstract
In contrast to animals, the life cycle of higher plants alternates between a gamete-producing (gametophyte) and a spore-producing (sporophyte) generation. The female gametophyte of angiosperms consists of four distinct cell types, including two gametes, the egg and the central cell, which give rise to embryo and endosperm, respectively. Based on a combined subtractive hybridization and virtual subtraction approach in wheat (Triticum aestivum L.), we have isolated a class of transcription factors not found in animal genomes, the RKD (RWP-RK domain-containing) factors, which share a highly conserved RWP-RK domain. Single-cell RT-PCR revealed that the genes TaRKD1 and TaRKD2 are preferentially expressed in the egg cell of wheat. The Arabidopsis genome contains five RKD genes, at least two of them, AtRKD1 and AtRKD2, are preferentially expressed in the egg cell of Arabidopsis. Ectopic expression of the AtRKD1 and AtRKD2 genes induces cell proliferation and the expression of an egg cell marker. Analyses of RKD-induced proliferating cells exhibit a shift of gene expression towards an egg cell-like transcriptome. Promoters of selected RKD-induced genes were shown to be predominantly active in the egg cell and can be activated by RKD in a transient protoplast expression assay. The data show that egg cell-specific RKD factors control a transcriptional program, which is characteristic for plant egg cells.
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Affiliation(s)
- Dávid Koszegi
- Leibniz Institute of Plant Genetics and Crop Plant Research (IPK), Gatersleben, Germany
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Schallau A, Arzenton F, Johnston AJ, Hähnel U, Koszegi D, Blattner FR, Altschmied L, Haberer G, Barcaccia G, Bäumlein H. Identification and genetic analysis of the APOSPORY locus in Hypericum perforatum L. Plant J 2010; 62:773-84. [PMID: 20202173 DOI: 10.1111/j.1365-313x.2010.04188.x] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/21/2023]
Abstract
The introduction of apomixis - seed formation without fertilization - into crop plants is a long-held goal of breeding research, since it would allow for the ready fixation of heterozygosity. The genetic basis of apomixis, whether of the aposporous or the diplosporous type, is still only poorly understood. Hypericum perforatum (St John's wort), a plant with a small genome and a short generation time, can be aposporous and/or parthenogenetic, and so represents an interesting model dicot for apomixis research. Here we describe a genetic analysis which first defined and then isolated a locus (designated HAPPY for Hypericum APOSPORY) associated with apospory. Amplified fragment length polymorphism (AFLP) profiling was used to generate a cleaved amplified polymorphic sequence (CAPS) marker for HAPPY which co-segregated with apospory but not with parthenogenesis, showing that these two components of apomixis are independently controlled. Apospory was inherited as a dominant simplex gene at the tetraploid level. Part of the HAPPY sequence is homologous to the Arabidopsis thaliana gene ARI7 encoding the ring finger protein ARIADNE7. This protein is predicted to be involved in various regulatory processes, including ubiquitin-mediated protein degradation. While the aposporous and sexual alleles of the HAPPY component HpARI were co-expressed in many parts of the plant, the gene product of the apomict's allele is truncated. Cloning HpARI represents the first step towards the full characterization of HAPPY and the elucidation of the molecular mechanisms underlying apomixis in H. perforatum.
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Affiliation(s)
- Anna Schallau
- Leibniz Institute of Plant Genetics and Crop Plant Research (IPK), Corrensstrasse 3, 06466 Gatersleben, Germany
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Aquea F, Johnston AJ, Cañon P, Grossniklaus U, Arce-Johnson P. TRAUCO, a Trithorax-group gene homologue, is required for early embryogenesis in Arabidopsis thaliana. J Exp Bot 2010; 61:1215-24. [PMID: 20118203 PMCID: PMC2826662 DOI: 10.1093/jxb/erp396] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/04/2009] [Revised: 12/16/2009] [Accepted: 12/21/2009] [Indexed: 05/18/2023]
Abstract
Embryogenesis is a critical stage during the plant life cycle in which a unicellular zygote develops into a multicellular organism. Co-ordinated gene expression is thus necessary for proper embryo development. Polycomb and Trithorax group genes are members of evolutionarily conserved machinery that maintains the correct expression patterns of key developmental regulators by repressing and activating gene transcription. TRAUCO (TRO), a gene homologous to the Trithorax group of genes that can functionally complement a BRE2P yeast mutant, has been identified in Arabidopsis thaliana. It is demonstrated that TRO is a nuclear gene product expressed during embryogenesis, and loss of TRO function leads to impaired early embryo development. Embryos that arrested at the globular stage in the tro-1 mutant allele were fully rescued by a TRO expression clone, a demonstration that the tro-1 mutation is a true loss-of-function in TRO. Our data have established that TRO is the first trithorax-group gene homologue in plants that is required for early embryogenesis.
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Affiliation(s)
- Felipe Aquea
- Departamento de Genética Molecular y Microbiología, Facultad de Ciencias Biológicas, Pontificia Universidad Católica de Chile, PO Box 114-D, Santiago, Chile
| | - Amal J. Johnston
- Leibniz Institute of Plant Genetics and Crop Plant Research (IPK) Department of Molecular Genetics. Corrensstrasse 3, D-06466 Gatersleben, Germany
- Institute of Plant Biology and Zürich-Basel Plant Science Center, University of Zürich, Zollikerstrasse 107, CH-8008 Zürich, Switzerland
| | - Paola Cañon
- Departamento de Genética Molecular y Microbiología, Facultad de Ciencias Biológicas, Pontificia Universidad Católica de Chile, PO Box 114-D, Santiago, Chile
| | - Ueli Grossniklaus
- Institute of Plant Biology and Zürich-Basel Plant Science Center, University of Zürich, Zollikerstrasse 107, CH-8008 Zürich, Switzerland
| | - Patricio Arce-Johnson
- Departamento de Genética Molecular y Microbiología, Facultad de Ciencias Biológicas, Pontificia Universidad Católica de Chile, PO Box 114-D, Santiago, Chile
- To whom correspondence should be addressed: E-mail:
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Johnston AJ, Meier P, Gheyselinck J, Wuest SEJ, Federer M, Schlagenhauf E, Becker JD, Grossniklaus U. Genetic subtraction profiling identifies genes essential for Arabidopsis reproduction and reveals interaction between the female gametophyte and the maternal sporophyte. Genome Biol 2008; 8:R204. [PMID: 17915010 PMCID: PMC2246279 DOI: 10.1186/gb-2007-8-10-r204] [Citation(s) in RCA: 114] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2007] [Revised: 09/10/2007] [Accepted: 10/03/2007] [Indexed: 11/30/2022] Open
Abstract
Genetic subtraction and expression profiling of wild-type Arabidopsis and a sporophytic mutant lacking an embryo sac identified 1,260 genes expressed in the embryo sac; a total of 527 genes were identified for their expression in ovules of mutants lacking an embryo sac. Background The embryo sac contains the haploid maternal cell types necessary for double fertilization and subsequent seed development in plants. Large-scale identification of genes expressed in the embryo sac remains cumbersome because of its inherent microscopic and inaccessible nature. We used genetic subtraction and comparative profiling by microarray between the Arabidopsis thaliana wild-type and a sporophytic mutant lacking an embryo sac in order to identify embryo sac expressed genes in this model organism. The influences of the embryo sac on the surrounding sporophytic tissues were previously thought to be negligible or nonexistent; we investigated the extent of these interactions by transcriptome analysis. Results We identified 1,260 genes as embryo sac expressed by analyzing both our dataset and a recently reported dataset, obtained by a similar approach, using three statistical procedures. Spatial expression of nine genes (for instance a central cell expressed trithorax-like gene, an egg cell expressed gene encoding a kinase, and a synergid expressed gene encoding a permease) validated our approach. We analyzed mutants in five of the newly identified genes that exhibited developmental anomalies during reproductive development. A total of 527 genes were identified for their expression in ovules of mutants lacking an embryo sac, at levels that were twofold higher than in the wild type. Conclusion Identification of embryo sac expressed genes establishes a basis for the functional dissection of embryo sac development and function. Sporophytic gain of expression in mutants lacking an embryo sac suggests that a substantial portion of the sporophytic transcriptome involved in carpel and ovule development is, unexpectedly, under the indirect influence of the embryo sac.
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Affiliation(s)
- Amal J Johnston
- Institute of Plant Biology and Zürich-Basel Plant Science Center, Zollikerstrasse, University of Zürich, CH-8008 Zürich, Switzerland
- Current address: Institute of Plant Sciences and Zürich-Basel Plant Science Center, ETH Zürich, Universitätstrasse, CH-8092 Zürich, Switzerland
| | - Patrick Meier
- Institute of Plant Biology and Zürich-Basel Plant Science Center, Zollikerstrasse, University of Zürich, CH-8008 Zürich, Switzerland
| | - Jacqueline Gheyselinck
- Institute of Plant Biology and Zürich-Basel Plant Science Center, Zollikerstrasse, University of Zürich, CH-8008 Zürich, Switzerland
| | - Samuel EJ Wuest
- Institute of Plant Biology and Zürich-Basel Plant Science Center, Zollikerstrasse, University of Zürich, CH-8008 Zürich, Switzerland
| | - Michael Federer
- Institute of Plant Biology and Zürich-Basel Plant Science Center, Zollikerstrasse, University of Zürich, CH-8008 Zürich, Switzerland
| | - Edith Schlagenhauf
- Institute of Plant Biology and Zürich-Basel Plant Science Center, Zollikerstrasse, University of Zürich, CH-8008 Zürich, Switzerland
| | - Jörg D Becker
- Centro de Biologia do Desenvolvimento, Instituto Gulbenkian de Ciência, Rua da Quinta Grande, PT-2780-156 Oeiras, Portugal
| | - Ueli Grossniklaus
- Institute of Plant Biology and Zürich-Basel Plant Science Center, Zollikerstrasse, University of Zürich, CH-8008 Zürich, Switzerland
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Pickard JD, Hutchinson PJ, Coles JP, Steiner LA, Johnston AJ, Fryer TD, Coleman MR, Smielewski P, Chatfield DA, Aigbirhio F, Williams GB, Rice K, Clark JC, Salmond CH, Sahakian BJ, Bradley PG, Carpenter TA, Salvador R, Pena A, Gillard JH, Cunningham AS, Piechnik S, Czosnyka M, Menon DK. Imaging of cerebral blood flow and metabolism in brain injury in the ICU. Acta Neurochir Suppl 2006; 95:459-64. [PMID: 16463901 DOI: 10.1007/3-211-32318-x_94] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 03/07/2023]
Abstract
The heterogeneity of the initial insult and subsequent pathophysiology has made both the study of human head injury and design of randomised controlled trials exceptionally difficult. The combination of multimodality bedside monitoring and functional brain imaging positron emission tomography (PET) and magnetic resonance (MR), incorporated within a Neurosciences Critical Care Unit, provides the resource required to study critically ill patients after brain injury from initial ictus through recovery from coma and rehabilitation to final outcome. Methods to define cerebral ischemia in the context of altered cerebral oxidative metabolism have been developed, traditional therapies for intracranial hypertension re-evaluated and bedside monitors cross-validated. New modelling and analytical approaches have been developed.
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Affiliation(s)
- J D Pickard
- Wolfson Brain Imaging Centre, University of Cambridge, Addenbrookes Hospital, Cambridge, UK.
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15
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Wheeler DW, Whittlestone KD, Salvador R, Wood DF, Johnston AJ, Smith HL, Menon DK. Influence of improved teaching on medical students’ acquisition and retention of drug administration skills. Br J Anaesth 2006; 96:48-52. [PMID: 16311282 DOI: 10.1093/bja/aei280] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
BACKGROUND Drug administration error is a major problem causing substantial morbidity and mortality worldwide. Lack of education about drug administration appears to be a causative factor. We devised an online teaching module for medical students and assessed its short- and long-term efficacy. METHODS One hundred and thirty clinical medical students were invited to undertake additional, online, teaching about drug administration. Those participating were identified and the number of web pages viewed recorded. The students' knowledge retention was tested by means of drug administration questions incorporated into routine assessments and examinations over the next 6 months. Other indices of all students' performance were recorded to correct for confounding factors. RESULTS Just over half (52%) responded to the invitation to participate. The amount of interest they showed in the teaching module correlated positively with their performance in questions about drug administration, although the latter waned over time. Surprisingly, correcting for students' general ability and keenness revealed that the less able students were most likely to undertake the teaching module. CONCLUSIONS Additional online teaching about drug administration improves students' knowledge of the topic but clearly requires reinforcement; however, only about half the students took up the option. Medical students must acquire these fundamental skills, and online teaching can help. Medical educators must ensure that drug administration is taught formally to all students as part of the curriculum and must understand that it may require additional teaching.
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Affiliation(s)
- D W Wheeler
- University Department of Anaesthesia, University of Cambridge, Addenbrooke's Hospital, Cambridge CB2 2QQ, UK.
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Cunningham AS, Salvador R, Coles JP, Chatfield DA, Bradley PG, Johnston AJ, Steiner LA, Fryer TD, Aigbirhio FI, Smielewski P, Williams GB, Carpenter TA, Gillard JH, Pickard JD, Menon DK. Physiological thresholds for irreversible tissue damage in contusional regions following traumatic brain injury. Brain 2005; 128:1931-42. [PMID: 15888537 DOI: 10.1093/brain/awh536] [Citation(s) in RCA: 107] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Cerebral ischaemia appears to be an important mechanism of secondary neuronal injury in traumatic brain injury (TBI) and is an important predictor of outcome. To date, the thresholds of cerebral blood flow (CBF) and cerebral oxygen utilization (CMRO(2)) for irreversible tissue damage used in TBI studies have been adopted from experimental and clinical ischaemic stroke studies. Identification of irreversibly damaged tissue in the acute phase following TBI could have considerable therapeutic and prognostic implications. However, it is questionable whether stroke thresholds are applicable to TBI. Therefore, the aim of this study was to determine physiological thresholds for the development of irreversible tissue damage in contusional and pericontusional regions in TBI, and to determine the ability of such thresholds to accurately differentiate irreversibly damaged tissue. This study involved 14 patients with structural abnormalities on late-stage MRI, all of whom had been studied with (15)O PET within 72 h of TBI. Lesion regions of interest (ROI) and non-lesion ROIs were constructed on late-stage MRIs and applied to co-registered PET maps of CBF, CMRO(2) and oxygen extraction fraction (OEF). From the entire population of voxels in non-lesion ROIs, we determined thresholds for the development of irreversible tissue damage as the lower limit of the 95% confidence interval for CBF, CMRO(2) and OEF. To test the ability of a physiological variable to differentiate lesion and non-lesion tissue, we constructed probability curves, demonstrating the ability of a physiological variable to predict lesion and non-lesion outcomes. The lower limits of the 95% confidence interval for CBF, CMRO(2) and OEF in non-lesion tissue were 15.0 ml/100 ml/min, 36.7 mumol/100 ml/min and 25.9% respectively. Voxels below these values were significantly more frequent in lesion tissue (all P < 0.005, Mann-Whitney U-test). However, a significant proportion of lesion voxels had values above these thresholds, so that definition of the full extent of irreversible tissue damage would not be possible based upon single physiological thresholds. We conclude that, in TBI, the threshold of CBF below which irreversible tissue damage consistently occurs differs from the classical CBF threshold for stroke (where similar methodology is used to define such thresholds). The CMRO(2) threshold is comparable to that reported in the stroke literature. At a voxel-based level, however (and in common with ischaemic stroke), the extent of irreversible tissue damage cannot be accurately predicted by early abnormalities of any single physiological variable.
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Affiliation(s)
- A S Cunningham
- Division of Anaesthesia, Department of Medicine, University of Cambridge, Cambridge, UK
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Steiner LA, Balestreri M, Johnston AJ, Coles JP, Smielewski P, Pickard JD, Menon DK, Czosnyka M. Predicting the response of intracranial pressure to moderate hyperventilation. Acta Neurochir (Wien) 2005; 147:477-83; discussion 483. [PMID: 15770347 DOI: 10.1007/s00701-005-0510-x] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2004] [Accepted: 02/03/2005] [Indexed: 12/01/2022]
Abstract
BACKGROUND Hyperventilation may cause brain ischaemia after traumatic brain injury. However, moderate reductions in PaCO(2) are still an option in the management of raised intracranial pressure (ICP) under some circumstances. Being able to predict the ICP-response to such an intervention would be advantageous. We investigated the ability of pre-hyperventilation ICP and cerebrospinal compensatory reserve to predict the reduction in ICP achievable with moderate hyperventilation in head injured patients. METHODS Thirty head injured patients requiring sedation and mechanical ventilation were investigated. ICP was monitored via an intraparenchymal probe and intracranial cerebrospinal compensatory reserve was assessed using an index (R(ap)) based on the relationship between mean ICP and its pulse amplitude. Measurements were made at a constant level of PaCO(2) during a 20-minute baseline period. The patients were then subjected to an acute decrease in PaCO(2) of approximately 1 kPa and, after an equilibration period of 10 minutes, measurements were again made at a constant level of PaCO(2) for a further 20 minutes. A multiple linear regression model, incorporating baseline PaCO(2), ICP, and R(ap) was used to identify the relevant predictors of ICP reduction. FINDINGS Baseline ICP and R(ap) were both significant predictors of ICP-reduction (p=0.02 and 0.001 respectively) with R(ap) being the more powerful parameter. CONCLUSIONS A model based on cerebrospinal compensatory reserve and ICP can predict the achievable ICP-reduction and may potentially be used to optimise patient selection and intensity of hyperventilation.
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Affiliation(s)
- L A Steiner
- Academic Neurosurgery, Addenbrooke's Hospital, Cambridge, United Kingdom.
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Johnston AJ, Hall JM, Levy DM. Anaesthesia with remifentanil and rocuronium for caesarean section in a patient with long-QT syndrome and an automatic implantable cardioverter-defibrillator. Int J Obstet Anesth 2005; 9:133-6. [PMID: 15321099 DOI: 10.1054/ijoa.1999.0362] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
A 24-year-old woman with congenital long-QT syndrome (LQTS) required caesarean section at 32 weeks' gestation. Her risk of premature death from malignant ventricular tachyarrhythmias had necessitated implantation of an automatic cardioverter-defibrillator (AICD) with pacemaker capability. The patient expressed a preference for general anaesthesia. To minimise the risk of increased serum catecholamine concentrations and consequent ventricular arrhythmias, an analgesia-based regimen was chosen. With cardioversion, defibrillation, and antitachycardia pacing functions of the AICD selectively deactivated, anaesthesia was induced with bolus doses of thiopentone and remifentanil. Rocuronium was used for neuromuscular block. Anaesthesia was maintained with nitrous oxide and isoflurane, supplemented by a remifentanil infusion. We outline the pathophysiology and treatment of LQTS, and discuss the anaesthetic management of an obstetric patient with the congenital syndrome. This is the first reported case of caesarean section in a patient with an AICD, and the first description of the use of either remifentanil or rocuronium in LQTS.
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Affiliation(s)
- A J Johnston
- Anaesthetics Directorate, University Hospital NHS Trust, Queen's Medical Centre, Nottingham, UK
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Steiner LA, Balestreri M, Johnston AJ, Coles JP, Chatfield DA, Pickard JD, Menon DK, Czosnyka M. Effects of moderate hyperventilation on cerebrovascular pressure-reactivity after head injury. Acta Neurochir Suppl 2005; 95:17-20. [PMID: 16463812 DOI: 10.1007/3-211-32318-x_4] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/06/2023]
Abstract
In volunteers, hyperventilation improves autoregulation. However, in head-injured patients, hyperventilation-induced deterioration and improvement of autoregulation have been reported. We have re-examined this question using an index of pressure reactivity. Thirty patients with severe or moderate head-injury were studied. Arterial blood pressure, cerebral perfusion pressure (CPP), and intracranial pressure (ICP) were recorded over 20 minute epochs separated by ten minutes of equilibration at baseline and during moderate (>3.5 kPa) hyperventilation. End-tidal CO2 was constant during each phase of data acquisition. Pressure reactivity was assessed using an index 'PRx' based on the response of ICP to spontaneous blood pressure changes. Hyperventilation decreased PaCO2 from 5.1 +/- 0.4 to 4.4 +/- 0.4 kPa (p < 0.0001). ICP decreased by 3.7 +/- 2.2 mmHg (p < 0.001). CPP increased by 5.9 +/- 8.2 mmHg (p < 0.001). Overall, PRx did not change significantly with hyperventilation. However, there was a significant negative correlation between baseline PRx and the change in PRx (r = -0.71, p < 0.0001). This suggests that patients with disturbed pressure-reactivity may improve, whereas patients with intact pressure reactivity remain largely unchanged. Our data suggest that the response of pressure reactivity to hyperventilation is heterogeneous. This could be due to hyperventilation-induced changes in cerebral metabolism, or the change in CPP.
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Affiliation(s)
- L A Steiner
- Academic Neurosurgery, Addenbrooke's Hospital, Cambridge, UK
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Johnston AJ, Steiner LA, Chatfield DA, Coleman MR, Coles JP, Al-Rawi PG, Menon DK, Gupta AK. Effects of propofol on cerebral oxygenation and metabolism after head injury. Br J Anaesth 2004; 91:781-6. [PMID: 14633744 DOI: 10.1093/bja/aeg256] [Citation(s) in RCA: 46] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
BACKGROUND Flow-metabolism coupling is thought to be deranged after traumatic brain injury, while the effects of propofol on flow-metabolism coupling are controversial. We have used a step increase in target plasma propofol concentration in head injured patients to explore flow-metabolism coupling in these patients. METHODS Ten patients with a moderate to severe head injury received a step increase in propofol target controlled infusion of 2 microg x ml(-1). Cerebral tissue gas measurements were recorded using a multimodal sensor, and regional chemistry was assessed using microdialysis. Arterial-jugular venous oxygen differences (AVDO(2)) were measured and all patients had cortical function monitoring (EEG). RESULTS The step increase in propofol led to a large increase in EEG burst-suppression ratio (0% (range 0-1.1) to 46.1% (range 0-61.7), P<0.05); however, this did not significantly change tissue gas levels, tissue chemistry, or AVDO(2). CONCLUSIONS Flow-metabolism coupling remains intact during a step increase in propofol after traumatic brain injury. The EEG burst-suppression induced by propofol after traumatic brain injury does not appear to be a useful therapeutic tool in reducing the level of regional ischaemic burden.
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Affiliation(s)
- A J Johnston
- University of Cambridge Department of Anaesthesia, Box 93, Cambridge CB2 2QQ, UK.
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Abstract
There has long been an appreciation that cerebral blood flow is modulated to ensure adequate cerebral oxygen delivery in the face of systemic hypoxaemia. There is increasing appreciation of the modulatory role of hyperoxia in the cerebral circulation and a consideration of the effects of such modulation on the maintenance of cerebral tissue oxygen concentration. These newer findings are particularly important in view of the fact that cerebrovascular and tissue oxygen responses to hyperoxia may change in disease. Such alterations provide important insights into pathophysiological mechanisms and may provide novel targets for therapy. However, before the modulatory effects of hyperoxia can be used for diagnosis, to predict prognosis or to direct therapy, a more detailed analysis and understanding of the physiological concepts behind this modulation are required, as are the limitations of the measurement tools used to define the modulation. This overview summarizes the available information in this area and suggests some avenues for further research.
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Affiliation(s)
- A J Johnston
- University of Cambridge Department of Anaesthetics, Box 93 and Academic Neurosurgery, Addenbrooke's Hospital, Cambridge CB2 2QQ, UK.
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Steiner LA, Johnston AJ, Salvador R, Czosnyka M, Menon DK. Validation of a tonometric noninvasive arterial blood pressure monitor in the intensive care setting. Anaesthesia 2003; 58:448-54. [PMID: 12694001 DOI: 10.1046/j.1365-2044.2003.03122.x] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Intra-arterial measurement is considered the gold standard for continuous, beat-to-beat arterial blood pressure monitoring. However, arterial cannulation can be difficult and may cause complications such as thrombosis and ischaemia. Recently, a tonometric system, the Colin CBM-7000 has been developed for noninvasive beat-to-beat measurement of arterial blood pressure from the radial artery. We assessed the level of agreement between the CBM-7000 and invasive radial artery measurements in 15 patients on a neuro-intensive care unit. Agreement of systolic, diastolic and mean arterial pressure values was limited, with approximately 34% of mean arterial pressures differing by over 10 mmHg. In many cases, this was due to a downward drift of the noninvasive measurements over time. Furthermore, there was a tendency to underestimate low pressures and overestimate high pressures. In our opinion, the Colin CBM-7000 cannot be recommended for continuous blood pressure monitoring in the intensive care setting.
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Affiliation(s)
- L A Steiner
- University Department of Anaesthesia and Academic Neurosurgery, Box 167, Addenbrooke's Hospital, Cambridge CB2 2QQ, UK.
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Abstract
BACKGROUND A reduction in the arterial partial pressure of CO2 (PaCO2) leads to a rapid reduction in cerebral blood flow (CBF). However, despite continuing hypocapnia there is secondary recovery of CBF over time as a result of increases in lactic acid production. Hyperoxia is thought to modulate the production of lactic acid. This study examined the kinetics of middle cerebral artery flow velocity (MCA FV) reduction during hyperventilation, and its modulation by hyperoxia. METHODS Cerebral blood flow was assessed using transcranial Doppler ultrasound in nine healthy, awake human volunteers. Subjects were ventilated, via a mouthpiece, to achieve a stable end-tidal CO2 (PETCO2). After a 20-min baseline period the minute volume on the ventilator was passively increased by approximately 20% to reduce PETCO2 by 0.75-1 kPa. After a 10-min stabilization period the new PETCO2 level was maintained at a constant level for 20 min, and MCA FV recovery was measured during this 20-min period. Subjects undertook the protocol breathing air and breathing 100% oxygen. RESULTS The PETCO2 level was (mean +/- SD) 4.9 +/- 0.4 kPa (normoxia baseline), 4.0 +/- 0.3 kPa (normoxia hyperventilation), 4.6 +/- 0.4 kPa (hyperoxia baseline) and 3.9 +/- 0.4 kPa (hyperoxia hyperventilation). CO2 reactivity was significantly lower with normoxia than hyperoxia (16.5 +/- 3.8 vs. 21.2 +/- 4.6 % kPa-1; P< 0.05). Middle cerebral artery FV recovery was significantly more rapid with normoxia than hyperoxia (0.23 +/- 0.17 vs. 0.08 +/- 0.1 % baseline min-1; P< 0.01). CONCLUSIONS Our results suggest that cerebral hemodynamic responses to moderate hyperventilation are different in normoxic and hyperoxic conditions. Clinical assessment of CO2 reactivity and CBF recovery during hyperventilation should take the degree of arterial oxygenation into account.
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Affiliation(s)
- A J Johnston
- Department of Anaesthetics, Addenbrooke's Hospital, University of Cambridge, Academic Neurosurgery, Addenbrooke's Hospital, Cambridge, UK.
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Steiner LA, Balestreri M, Johnston AJ, Czosnyka M, Coles JP, Pickard JD, Menon DK. Hyperventilation-induced reductions in cerebral blood flow velocity outlive the reduction in intracranial pressure in head-injured patients. Crit Care 2003; 7. [PMCID: PMC3301519 DOI: 10.1186/cc1963] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022] Open
Affiliation(s)
- LA Steiner
- Academic Neurosurgery, Addenbrooke's Hospital, Cambridge, UK,Department of Anaesthesia, Addenbrooke's Hospital, Cambridge, UK
| | - M Balestreri
- Academic Neurosurgery, Addenbrooke's Hospital, Cambridge, UK
| | - AJ Johnston
- Department of Anaesthesia, Addenbrooke's Hospital, Cambridge, UK
| | - M Czosnyka
- Academic Neurosurgery, Addenbrooke's Hospital, Cambridge, UK
| | - JP Coles
- Department of Anaesthesia, Addenbrooke's Hospital, Cambridge, UK
| | - JD Pickard
- Academic Neurosurgery, Addenbrooke's Hospital, Cambridge, UK
| | - DK Menon
- Department of Anaesthesia, Addenbrooke's Hospital, Cambridge, UK
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Johnston AJ. [Not Available]. Study Sess Can Cathol Hist Assoc 2001; 48:5-25. [PMID: 11633339] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 02/21/2023]
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Conn AG, Johnston AJ. Failure of chest X-rays to diagnose pneumothoraces after blunt trauma. Anaesthesia 1998; 53:612-3. [PMID: 9709169] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
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Milling M, Park C, Erdman IE, Todd EC, Casey J, Fish N, Gale RA, Johnston AJ, Pivnick H. Staphylococcal food poisoning from commercially prepared barbecued chicken, from "hot" turkey sandwiches, and from ham. Can J Public Health 1971; 62:382-5. [PMID: 5137620] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 01/14/2023]
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