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Augustine J, Pavlou S, Harkin K, Stitt AW, Xu H, Chen M. IL-33 regulates Müller cell-mediated retinal inflammation and neurodegeneration in diabetic retinopathy. Dis Model Mech 2023; 16:dmm050174. [PMID: 37671525 PMCID: PMC10499035 DOI: 10.1242/dmm.050174] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2023] [Accepted: 07/31/2023] [Indexed: 09/07/2023] Open
Abstract
Diabetic retinopathy (DR) is characterised by dysfunction of the retinal neurovascular unit, leading to visual impairment and blindness. Müller cells are key components of the retinal neurovascular unit and diabetes has a detrimental impact on these glial cells, triggering progressive neurovascular pathology of DR. Amongst many factors expressed by Müller cells, interleukin-33 (IL-33) has an established immunomodulatory role, and we investigated the role of endogenous IL-33 in DR. The expression of IL-33 in Müller cells increased during diabetes. Wild-type and Il33-/- mice developed equivalent levels of hyperglycaemia and weight loss following streptozotocin-induced diabetes. Electroretinogram a- and b-wave amplitudes, neuroretina thickness, and the numbers of cone photoreceptors and ganglion cells were significantly reduced in Il33-/- diabetic mice compared with those in wild-type counterparts. The Il33-/- diabetic retina also exhibited microglial activation, sustained gliosis, and upregulation of pro-inflammatory cytokines and neurotrophins. Primary Müller cells from Il33-/- mice expressed significantly lower levels of neurotransmitter-related genes (Glul and Slc1a3) and neurotrophin genes (Cntf, Lif, Igf1 and Ngf) under high-glucose conditions. Our results suggest that deletion of IL-33 promotes inflammation and neurodegeneration in DR, and that this cytokine is critical for regulation of glutamate metabolism, neurotransmitter recycling and neurotrophin secretion by Müller cells.
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Affiliation(s)
- Josy Augustine
- Wellcome-Wolfson Institute for Experimental Medicine, School of Medicine, Dentistry and Biomedical Sciences, Queen's University Belfast, Belfast BT9 7BL, Northern Ireland, UK
| | - Sofia Pavlou
- Wellcome-Wolfson Institute for Experimental Medicine, School of Medicine, Dentistry and Biomedical Sciences, Queen's University Belfast, Belfast BT9 7BL, Northern Ireland, UK
| | - Kevin Harkin
- Wellcome-Wolfson Institute for Experimental Medicine, School of Medicine, Dentistry and Biomedical Sciences, Queen's University Belfast, Belfast BT9 7BL, Northern Ireland, UK
| | - Alan W. Stitt
- Wellcome-Wolfson Institute for Experimental Medicine, School of Medicine, Dentistry and Biomedical Sciences, Queen's University Belfast, Belfast BT9 7BL, Northern Ireland, UK
| | - Heping Xu
- Wellcome-Wolfson Institute for Experimental Medicine, School of Medicine, Dentistry and Biomedical Sciences, Queen's University Belfast, Belfast BT9 7BL, Northern Ireland, UK
| | - Mei Chen
- Wellcome-Wolfson Institute for Experimental Medicine, School of Medicine, Dentistry and Biomedical Sciences, Queen's University Belfast, Belfast BT9 7BL, Northern Ireland, UK
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Lin JQ, Khuperkar D, Pavlou S, Makarchuk S, Patikas N, Lee FC, Zbiegly JM, Kang J, Field SF, Bailey DM, Freeman JL, Ule J, Metzakopian E, Ruepp MD, Mallucci GR. HNRNPH1 regulates the neuroprotective cold-shock protein RBM3 expression through poison exon exclusion. EMBO J 2023:e113168. [PMID: 37248947 DOI: 10.15252/embj.2022113168] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2022] [Revised: 05/07/2023] [Accepted: 05/11/2023] [Indexed: 05/31/2023] Open
Abstract
Enhanced expression of the cold-shock protein RNA binding motif 3 (RBM3) is highly neuroprotective both in vitro and in vivo. Whilst upstream signalling pathways leading to RBM3 expression have been described, the precise molecular mechanism of RBM3 cold induction remains elusive. To identify temperature-dependent modulators of RBM3, we performed a genome-wide CRISPR-Cas9 knockout screen using RBM3-reporter human iPSC-derived neurons. We found that RBM3 mRNA and protein levels are robustly regulated by several splicing factors, with heterogeneous nuclear ribonucleoprotein H1 (HNRNPH1) being the strongest positive regulator. Splicing analysis revealed that moderate hypothermia significantly represses the inclusion of a poison exon, which, when retained, targets the mRNA for nonsense-mediated decay. Importantly, we show that HNRNPH1 mediates this cold-dependent exon skipping via its thermosensitive interaction with a G-rich motif within the poison exon. Our study provides novel mechanistic insights into the regulation of RBM3 and provides further targets for neuroprotective therapeutic strategies.
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Affiliation(s)
- Julie Qiaojin Lin
- UK Dementia Research Institute and Department of Clinical Neurosciences, University of Cambridge, Cambridge Biomedical Campus, Cambridge, UK
- UK Dementia Research Institute, King's College London, London, UK
| | - Deepak Khuperkar
- UK Dementia Research Institute and Department of Clinical Neurosciences, University of Cambridge, Cambridge Biomedical Campus, Cambridge, UK
- UK Dementia Research Institute, King's College London, London, UK
| | - Sofia Pavlou
- UK Dementia Research Institute and Department of Clinical Neurosciences, University of Cambridge, Cambridge Biomedical Campus, Cambridge, UK
- Open Targets, Cambridgeshire, UK
| | - Stanislaw Makarchuk
- UK Dementia Research Institute and Department of Clinical Neurosciences, University of Cambridge, Cambridge Biomedical Campus, Cambridge, UK
| | - Nikolaos Patikas
- UK Dementia Research Institute and Department of Clinical Neurosciences, University of Cambridge, Cambridge Biomedical Campus, Cambridge, UK
| | - Flora Cy Lee
- UK Dementia Research Institute, King's College London, London, UK
- The Francis Crick Institute, London, UK
| | - Julia M Zbiegly
- UK Dementia Research Institute and Department of Clinical Neurosciences, University of Cambridge, Cambridge Biomedical Campus, Cambridge, UK
| | - Jianning Kang
- Tsinghua-Peking Joint Center for Life Sciences, School of Medicine and School of Life Sciences, Tsinghua University, Beijing, China
| | - Sarah F Field
- UK Dementia Research Institute and Department of Clinical Neurosciences, University of Cambridge, Cambridge Biomedical Campus, Cambridge, UK
- Open Targets, Cambridgeshire, UK
| | - David Md Bailey
- UK Dementia Research Institute and Department of Clinical Neurosciences, University of Cambridge, Cambridge Biomedical Campus, Cambridge, UK
| | - Joshua L Freeman
- UK Dementia Research Institute and Department of Clinical Neurosciences, University of Cambridge, Cambridge Biomedical Campus, Cambridge, UK
- Altos Labs Cambridge Institute of Science, Cambridge, UK
| | - Jernej Ule
- UK Dementia Research Institute, King's College London, London, UK
- The Francis Crick Institute, London, UK
| | - Emmanouil Metzakopian
- UK Dementia Research Institute and Department of Clinical Neurosciences, University of Cambridge, Cambridge Biomedical Campus, Cambridge, UK
| | - Marc-David Ruepp
- UK Dementia Research Institute, King's College London, London, UK
| | - Giovanna R Mallucci
- UK Dementia Research Institute and Department of Clinical Neurosciences, University of Cambridge, Cambridge Biomedical Campus, Cambridge, UK
- Altos Labs Cambridge Institute of Science, Cambridge, UK
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Pavlou S, Foskolou S, Patikas N, Field SF, Papachristou EK, Santos CD, Edwards AR, Kishore K, Ansari R, Rajan SS, Fernandes HJR, Metzakopian E. CRISPR-Cas9 genetic screen leads to the discovery of L-Moses, a KAT2B inhibitor that attenuates Tunicamycin-mediated neuronal cell death. Sci Rep 2023; 13:3934. [PMID: 36894612 PMCID: PMC9998435 DOI: 10.1038/s41598-023-31141-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2022] [Accepted: 03/07/2023] [Indexed: 03/11/2023] Open
Abstract
Accumulation of aggregated and misfolded proteins, leading to endoplasmic reticulum stress and activation of the unfolded protein response, is a hallmark of several neurodegenerative disorders, including Alzheimer's and Parkinson's disease. Genetic screens are powerful tools that are proving invaluable in identifying novel modulators of disease associated processes. Here, we performed a loss-of-function genetic screen using a human druggable genome library, followed by an arrayed-screen validation, in human iPSC-derived cortical neurons. We identified and genetically validated 13 genes, whose knockout was neuroprotective against Tunicamycin, a glycoprotein synthesis inhibitor widely used to induce endoplasmic reticulum stress. We also demonstrated that pharmacological inhibition of KAT2B, a lysine acetyltransferase identified by our genetic screens, by L-Moses, attenuates Tunicamycin-mediated neuronal cell death and activation of CHOP, a key pro-apoptotic member of the unfolded protein response in both cortical and dopaminergic neurons. Follow-up transcriptional analysis suggested that L-Moses provided neuroprotection by partly reversing the transcriptional changes caused by Tunicamycin. Finally, L-Moses treatment attenuated total protein levels affected by Tunicamycin, without affecting their acetylation profile. In summary, using an unbiased approach, we identified KAT2B and its inhibitor, L-Moses, as potential therapeutic targets for neurodegenerative diseases.
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Affiliation(s)
- Sofia Pavlou
- UK Dementia Research Institute, Department of Clinical Neurosciences, Cambridge Biomedical Campus, University of Cambridge, Cambridge, CB2 0AH, UK.
- Open Targets, Wellcome Genome Campus, Hinxton, Cambridge, CB10 1SA, UK.
| | - Stefanie Foskolou
- UK Dementia Research Institute, Department of Clinical Neurosciences, Cambridge Biomedical Campus, University of Cambridge, Cambridge, CB2 0AH, UK
- Open Targets, Wellcome Genome Campus, Hinxton, Cambridge, CB10 1SA, UK
| | - Nikolaos Patikas
- UK Dementia Research Institute, Department of Clinical Neurosciences, Cambridge Biomedical Campus, University of Cambridge, Cambridge, CB2 0AH, UK
| | - Sarah F Field
- UK Dementia Research Institute, Department of Clinical Neurosciences, Cambridge Biomedical Campus, University of Cambridge, Cambridge, CB2 0AH, UK
- Open Targets, Wellcome Genome Campus, Hinxton, Cambridge, CB10 1SA, UK
| | - Evangelia K Papachristou
- Cancer Research UK Cambridge Institute, University of Cambridge, Li Ka Shing Centre, Robinson Way, Cambridge, CB2 0RE, UK
| | - Clive D' Santos
- Cancer Research UK Cambridge Institute, University of Cambridge, Li Ka Shing Centre, Robinson Way, Cambridge, CB2 0RE, UK
| | - Abigail R Edwards
- Cancer Research UK Cambridge Institute, University of Cambridge, Li Ka Shing Centre, Robinson Way, Cambridge, CB2 0RE, UK
| | - Kamal Kishore
- Cancer Research UK Cambridge Institute, University of Cambridge, Li Ka Shing Centre, Robinson Way, Cambridge, CB2 0RE, UK
| | - Rizwan Ansari
- UK Dementia Research Institute, Department of Clinical Neurosciences, Cambridge Biomedical Campus, University of Cambridge, Cambridge, CB2 0AH, UK
| | - Sandeep S Rajan
- UK Dementia Research Institute, Department of Clinical Neurosciences, Cambridge Biomedical Campus, University of Cambridge, Cambridge, CB2 0AH, UK
- Open Targets, Wellcome Genome Campus, Hinxton, Cambridge, CB10 1SA, UK
| | - Hugo J R Fernandes
- UK Dementia Research Institute, Department of Clinical Neurosciences, Cambridge Biomedical Campus, University of Cambridge, Cambridge, CB2 0AH, UK
- Open Targets, Wellcome Genome Campus, Hinxton, Cambridge, CB10 1SA, UK
| | - Emmanouil Metzakopian
- UK Dementia Research Institute, Department of Clinical Neurosciences, Cambridge Biomedical Campus, University of Cambridge, Cambridge, CB2 0AH, UK.
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Affiliation(s)
- Miao Tang
- Centre for Experimental Medicine School of Medicine Dentistry & Biomedical Sciences Queen’s University Belfast Belfast UK
| | - Sofia Pavlou
- Centre for Experimental Medicine School of Medicine Dentistry & Biomedical Sciences Queen’s University Belfast Belfast UK
| | - Mei Chen
- Centre for Experimental Medicine School of Medicine Dentistry & Biomedical Sciences Queen’s University Belfast Belfast UK
| | - Heping Xu
- Centre for Experimental Medicine School of Medicine Dentistry & Biomedical Sciences Queen’s University Belfast Belfast UK
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Augustine J, Pavlou S, Ali I, Harkin K, Ozaki E, Campbell M, Stitt AW, Xu H, Chen M. IL-33 deficiency causes persistent inflammation and severe neurodegeneration in retinal detachment. J Neuroinflammation 2019; 16:251. [PMID: 31796062 PMCID: PMC6889479 DOI: 10.1186/s12974-019-1625-y] [Citation(s) in RCA: 28] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2019] [Accepted: 10/28/2019] [Indexed: 02/08/2023] Open
Abstract
Background Interleukin-33 (IL-33) belongs to the IL-1 cytokine family and resides in the nuclei of various cell types. In the neural retina, IL-33 is predominately expressed in Müller cells although its role in health and disease is ill-defined. Müller cell gliosis is a critical response during the acute phase of retinal detachment (RD), and in this study, we investigated if IL-33 was modulatory in the inflammatory and neurodegenerative pathology which is characteristic of this important clinical condition. Methods RD was induced by subretinal injection of sodium hyaluronate into C57BL/6 J (WT) and IL-33−/− mice and confirmed by fundus imaging and optical coherence tomography (OCT). The expression of inflammatory cytokines, complement components and growth factors was examined by RT-PCR. Retinal neurodegeneration, Müller cell activation and immune cell infiltration were assessed using immunohistochemistry. The expression of inflammatory cytokines in primary Müller cells and bone marrow-derived macrophages (BM-DMs) was assessed by RT-PCR and Cytometric Bead Array. Results RD persisted for at least 28 days after the injection of sodium hyaluronate, accompanied by significant cone photoreceptor degeneration. The mRNA levels of CCL2, C1ra, C1s, IL-18, IL-1β, TNFα, IL-33 and glial fibrillary acidic protein (GFAP) were significantly increased at day 1 post-RD, reduced gradually and, with the exception of GFAP and C1ra, returned to the basal levels by day 28 in WT mice. In IL-33−/− mice, RD induced an exacerbated inflammatory response with significantly higher levels of CCL2, IL-1β and GFAP when compared to WT. Sustained GFAP activation and immune cell infiltration was detected at day 28 post-RD in IL-33−/− mice. Electroretinography revealed a lower A-wave amplitude at day 28 post-RD in IL-33−/− mice compared to that in WT RD mice. IL-33−/− mice subjected to RD also had significantly more severe cone photoreceptor degeneration compared to WT counterparts. Surprisingly, Müller cells from IL-33−/− mice expressed significantly lower levels of CCL2 and IL-6 compared with those from WT mice, particularly under hypoxic conditions, whereas IL-33−/− bone marrow-derived macrophages expressed higher levels of inducible nitric oxide synthase, TNFα, IL-1β and CCL2 after LPS + IFNγ stimulation compared to WT macrophages. Conclusion IL-33 deficiency enhanced retinal degeneration and gliosis following RD which was related to sustained subretinal inflammation from infiltrating macrophages. IL-33 may provide a previously unrecognised protective response by negatively regulating macrophage activation following retinal detachment.
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Affiliation(s)
- Josy Augustine
- Wellcome-Wolfson Institute for Experimental Medicine, School of Medicine, Dentistry & Biomedical Science, Queen's University Belfast, Belfast, Northern Ireland, UK
| | - Sofia Pavlou
- Wellcome-Wolfson Institute for Experimental Medicine, School of Medicine, Dentistry & Biomedical Science, Queen's University Belfast, Belfast, Northern Ireland, UK
| | - Imran Ali
- Wellcome-Wolfson Institute for Experimental Medicine, School of Medicine, Dentistry & Biomedical Science, Queen's University Belfast, Belfast, Northern Ireland, UK
| | - Kevin Harkin
- Wellcome-Wolfson Institute for Experimental Medicine, School of Medicine, Dentistry & Biomedical Science, Queen's University Belfast, Belfast, Northern Ireland, UK
| | - Ema Ozaki
- Smurfit Institute of Genetics, Trinity College Dublin, Dublin, Ireland
| | - Matthew Campbell
- Smurfit Institute of Genetics, Trinity College Dublin, Dublin, Ireland
| | - Alan W Stitt
- Wellcome-Wolfson Institute for Experimental Medicine, School of Medicine, Dentistry & Biomedical Science, Queen's University Belfast, Belfast, Northern Ireland, UK
| | - Heping Xu
- Wellcome-Wolfson Institute for Experimental Medicine, School of Medicine, Dentistry & Biomedical Science, Queen's University Belfast, Belfast, Northern Ireland, UK
| | - Mei Chen
- Wellcome-Wolfson Institute for Experimental Medicine, School of Medicine, Dentistry & Biomedical Science, Queen's University Belfast, Belfast, Northern Ireland, UK.
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Pavlou S, Augustine J, Cunning R, Harkin K, Stitt AW, Xu H, Chen M. Attenuating Diabetic Vascular and Neuronal Defects by Targeting P2rx7. Int J Mol Sci 2019; 20:ijms20092101. [PMID: 31035433 PMCID: PMC6540042 DOI: 10.3390/ijms20092101] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2019] [Revised: 04/23/2019] [Accepted: 04/25/2019] [Indexed: 02/06/2023] Open
Abstract
Retinal vascular and neuronal degeneration are established pathological features of diabetic retinopathy. Data suggest that defects in the neuroglial network precede the clinically recognisable vascular lesions in the retina. Therefore, new treatments that target early-onset neurodegeneration would be expected to have great value in preventing the early stages of diabetic retinopathy. Here, we show that the nucleoside reverse transcriptase inhibitor lamivudine (3TC), a newly discovered P2rx7 inhibitor, can attenuate progression of both neuronal and vascular pathology in diabetic retinopathy. We found that the expression of P2rx7 was increased in the murine retina as early as one month following diabetes induction. Compared to non-diabetic controls, diabetic mice treated with 3TC were protected against the formation of acellular capillaries in the retina. This occurred concomitantly with a maintenance in neuroglial function, as shown by improved a- and b-wave amplitude, as well as oscillatory potentials. An improvement in the number of GABAergic amacrine cells and the synaptophysin-positive area was also observed in the inner retina of 3TC-treated diabetic mice. Our data suggest that 3TC has therapeutic potential since it can target both neuronal and vascular defects caused by diabetes.
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Affiliation(s)
- Sofia Pavlou
- Centre for Experimental Medicine, School of Medicine, Dentistry & Biomedical Science, Queen's University Belfast, Belfast BT9 7BL, Northern Ireland, UK.
| | - Josy Augustine
- Centre for Experimental Medicine, School of Medicine, Dentistry & Biomedical Science, Queen's University Belfast, Belfast BT9 7BL, Northern Ireland, UK.
| | - Rónán Cunning
- Centre for Experimental Medicine, School of Medicine, Dentistry & Biomedical Science, Queen's University Belfast, Belfast BT9 7BL, Northern Ireland, UK.
| | - Kevin Harkin
- Centre for Experimental Medicine, School of Medicine, Dentistry & Biomedical Science, Queen's University Belfast, Belfast BT9 7BL, Northern Ireland, UK.
| | - Alan W Stitt
- Centre for Experimental Medicine, School of Medicine, Dentistry & Biomedical Science, Queen's University Belfast, Belfast BT9 7BL, Northern Ireland, UK.
| | - Heping Xu
- Centre for Experimental Medicine, School of Medicine, Dentistry & Biomedical Science, Queen's University Belfast, Belfast BT9 7BL, Northern Ireland, UK.
| | - Mei Chen
- Centre for Experimental Medicine, School of Medicine, Dentistry & Biomedical Science, Queen's University Belfast, Belfast BT9 7BL, Northern Ireland, UK.
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Wang L, Pavlou S, Du X, Bhuckory M, Xu H, Chen M. Glucose transporter 1 critically controls microglial activation through facilitating glycolysis. Mol Neurodegener 2019; 14:2. [PMID: 30634998 PMCID: PMC6329071 DOI: 10.1186/s13024-019-0305-9] [Citation(s) in RCA: 136] [Impact Index Per Article: 27.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2018] [Accepted: 01/02/2019] [Indexed: 12/18/2022] Open
Abstract
BACKGROUND Uncontrolled microglial activation contributes to the pathogenesis of various neurodegenerative diseases. Previous studies have shown that proinflammatory microglia are powered by glycolysis, which relays on high levels of glucose uptake. This study aimed to understand how glucose uptake is facilitated in active microglia and whether microglial activation can be controlled by restricting glucose uptake. METHODS Primary murine brain microglia, BV2 cells and the newly established microglial cell line B6M7 were treated with LPS (100 ng/ml) + IFNγ (100 ng/ml) or IL-4 (20 ng/ml) for 24 h. The expression of glucose transporters (GLUTs) was examined by PCR and Western blot. Glucose uptake by microglia was inhibited using the GLUT1-specific inhibitor STF31. The metabolic profiles were tested using the Glycolysis Stress Test and Mito Stress Test Kits using the Seahorse XFe96 Analyser. Inflammatory gene expression was examined by real-time RT-PCR and protein secretion by cytokine beads array. The effect of STF31 on microglial activation and neurodegeneraion was further tested in a mouse model of light-induced retinal degeneration. RESULTS The mRNA and protein of GLUT1, 3, 4, 5, 6, 8, 9, 10, 12, and 13 were detected in microglia. The expression level of GLUT1 was the highest among all GLUTs detected. LPS + IFNγ treatment further increased GLUT1 expression. STF31 dose-dependently reduced glucose uptake and suppressed Extracellular Acidification Rate (ECAR) in naïve, M(LPS + IFNγ) and M(IL-4) microglia. The treatment also prevented the upregulation of inflammatory cytokines including TNFα, IL-1β, IL-6, and CCL2 in M(LPS + IFNγ) microglia. Interestingly, the Oxygen Consumption Rates (OCR) was increased in M(LPS + IFNγ) microglia but reduced in M(IL-4) microglia by STF31 treatment. Intraperitoneal injection of STF31 reduced light-induced microglial activation and retinal degeneration. CONCLUSION Glucose uptake in microglia is facilitated predominately by GLUT1, particularly under inflammatory conditions. Targeting GLUT1 could be an effective approach to control neuroinflammation.
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Affiliation(s)
- Luxi Wang
- The Wellcome-Wolfson Institute of Experimental Medicine, School of Medicine, Dentistry and Biomedical Sciences, Queen's University Belfast, 97 Lisburn Road, Belfast, BT9 7BL, UK
| | - Sofia Pavlou
- The Wellcome-Wolfson Institute of Experimental Medicine, School of Medicine, Dentistry and Biomedical Sciences, Queen's University Belfast, 97 Lisburn Road, Belfast, BT9 7BL, UK
| | - Xuan Du
- The Wellcome-Wolfson Institute of Experimental Medicine, School of Medicine, Dentistry and Biomedical Sciences, Queen's University Belfast, 97 Lisburn Road, Belfast, BT9 7BL, UK
| | - Mohajeet Bhuckory
- The Wellcome-Wolfson Institute of Experimental Medicine, School of Medicine, Dentistry and Biomedical Sciences, Queen's University Belfast, 97 Lisburn Road, Belfast, BT9 7BL, UK
| | - Heping Xu
- The Wellcome-Wolfson Institute of Experimental Medicine, School of Medicine, Dentistry and Biomedical Sciences, Queen's University Belfast, 97 Lisburn Road, Belfast, BT9 7BL, UK.
| | - Mei Chen
- The Wellcome-Wolfson Institute of Experimental Medicine, School of Medicine, Dentistry and Biomedical Sciences, Queen's University Belfast, 97 Lisburn Road, Belfast, BT9 7BL, UK.
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Augustine J, Pavlou S, O'Hare M, Harkin K, Stitt A, Curtis T, Xu H, Chen M. Characterization of a Spontaneously Immortalized Murine Müller Glial Cell Line QMMuC-1. Invest Ophthalmol Vis Sci 2018; 59:1666-1674. [PMID: 29625493 DOI: 10.1167/iovs.17-23293] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
Purpose Müller glia are critical for the survival of retinal neurons and the integrity of retinal blood vessels. Müller glial cultures are important tools for investigating Müller glial pathophysiology. Here, we report a spontaneously immortalized Müller glial cell line originally cultured and subsequently cloned from mouse pups. The cell line, Queen's University Murine Müller glia Clone-1 (QMMuC-1), has been cultured for over 60 passages, has morphologic features like primary Müller cell (PMC) cultures and remains stable. Methods QMMuC-1 and PMC cells were processed for immunohistochemistry, quantitative RT-PCR, Western blotting, whole cell voltage-clamping, and bioenergetic profiling. Results Immunocytochemistry showed that QMMuC-1 express known Müller glial markers, including glutamine synthetase, glial fibrillary acidic protein (GFAP), alpha-smooth muscle actin (α-SMA), Aquaporin 4, Kir4.1, interleukin 33 (IL-33), and sex determining region Y (SRY)-box2 (Sox2), but not Cone arrestin, Calbindin 1, CD68, and ionized calcium-binding adapter molecule 1 (Iba1). Compared with PMC, QMMuC-1 express higher levels of chemokine (C-C motif) ligand 2 (Ccl2), VEGFA, and glutamate aspartate transporter (GLAST), but lower levels of interleukin 6 (IL-6), brain-derived neurotrophic factor (BDNF), insulin-like growth factor 1 (IGF1), and neurotrophin 3 (NTF3). Whole-cell patch clamp recordings demonstrated characteristic inward currents in response to L-glutamate and L-trans-pyrrolidine-2,4-dicarboxylic acid (PDC) by QMMuC-1 cells. The L-glutamate-induced current was significantly higher in QMMuC-1 cells compared with PMC. Bioenergetic profiling studies revealed similar levels of glycolysis and basal mitochondrial respiration between QMMuC-1 and PMC. However, mitochondrial spare capacity was significantly lower in QMMuC-1 compared with PMC. Conclusions Our results suggest that the QMMuC-1 Müller glial cell line retains key characteristics of PMC with its unique profiles in cytokine/neurotrophic factor expression and mitochondrial respiration. QMMuC-1 has utility as an invaluable tool for understanding the role of Müller glia in physiological and pathological conditions.
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Affiliation(s)
- Josy Augustine
- Wellcome-Wolfson Institute for Experimental Medicine, Queen's University Belfast, Northern Ireland, United Kingdom
| | - Sofia Pavlou
- Wellcome-Wolfson Institute for Experimental Medicine, Queen's University Belfast, Northern Ireland, United Kingdom
| | - Michael O'Hare
- Wellcome-Wolfson Institute for Experimental Medicine, Queen's University Belfast, Northern Ireland, United Kingdom
| | - Kevin Harkin
- Wellcome-Wolfson Institute for Experimental Medicine, Queen's University Belfast, Northern Ireland, United Kingdom
| | - Alan Stitt
- Wellcome-Wolfson Institute for Experimental Medicine, Queen's University Belfast, Northern Ireland, United Kingdom
| | - Tim Curtis
- Wellcome-Wolfson Institute for Experimental Medicine, Queen's University Belfast, Northern Ireland, United Kingdom
| | - Heping Xu
- Wellcome-Wolfson Institute for Experimental Medicine, Queen's University Belfast, Northern Ireland, United Kingdom
| | - Mei Chen
- Wellcome-Wolfson Institute for Experimental Medicine, Queen's University Belfast, Northern Ireland, United Kingdom
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Pavlou S, Lindsay J, Ingram R, Xu H, Chen M. Sustained high glucose exposure sensitizes macrophage responses to cytokine stimuli but reduces their phagocytic activity. BMC Immunol 2018; 19:24. [PMID: 29996768 PMCID: PMC6042333 DOI: 10.1186/s12865-018-0261-0] [Citation(s) in RCA: 110] [Impact Index Per Article: 18.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2018] [Accepted: 07/04/2018] [Indexed: 01/06/2023] Open
Abstract
Background Macrophages are tissue resident immune cells important for host defence and homeostasis. During diabetes, macrophages and other innate immune cells are known to have a pro-inflammatory phenotype, which is believed to contribute to the pathogenesis of various diabetic complications. However, diabetic patients are highly susceptible to bacterial infections, and often have impaired wound healing. The molecular mechanism underlying the paradox of macrophage function in diabetes is not fully understood. Recent evidence suggests that macrophage functions are governed by metabolic reprograming. Diabetes is a disorder that affects glucose metabolism; dysregulated macrophage function in diabetes may be related to alterations in their metabolic pathways. In this study, we seek to understand the effect of high glucose exposure on macrophage phenotype and functions. Results Bone marrow cells were cultured in short or long term high glucose and normal glucose medium; the number and phenotype of bone marrow derived macrophages were not affected by long-term high glucose treatment. Short-term high glucose increased the expression of IL-1β. Long-term high glucose increased the expression of IL-1β and TNFα but reduced the expression of IL-12p40 and nitric oxide production in M1 macrophage. The treatment also increased Arg-1 and IL-10 expression in M2 macrophages. Phagocytosis and bactericidal activity was reduced in long-term high glucose treated macrophages and peritoneal macrophages from diabetic mice. Long-term high glucose treatment reduced macrophage glycolytic capacity and glycolytic reserve without affecting mitochondrial ATP production and oxidative respiration. Conclusion Long-term high glucose sensitizes macrophages to cytokine stimulation and reduces phagocytosis and nitric oxide production, which may be related to impaired glycolytic capacity. Electronic supplementary material The online version of this article (10.1186/s12865-018-0261-0) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Sofia Pavlou
- Centre for Experimental Medicine, School of Medicine, Dentistry & Biomedical Science, Queen's University Belfast, Belfast, UK
| | - Jaime Lindsay
- Centre for Experimental Medicine, School of Medicine, Dentistry & Biomedical Science, Queen's University Belfast, Belfast, UK
| | - Rebecca Ingram
- Centre for Experimental Medicine, School of Medicine, Dentistry & Biomedical Science, Queen's University Belfast, Belfast, UK
| | - Heping Xu
- Centre for Experimental Medicine, School of Medicine, Dentistry & Biomedical Science, Queen's University Belfast, Belfast, UK
| | - Mei Chen
- Centre for Experimental Medicine, School of Medicine, Dentistry & Biomedical Science, Queen's University Belfast, Belfast, UK.
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Pavlou S, Wang L, Xu H, Chen M. Higher phagocytic activity of thioglycollate-elicited peritoneal macrophages is related to metabolic status of the cells. J Inflamm (Lond) 2017; 14:4. [PMID: 28203119 PMCID: PMC5301433 DOI: 10.1186/s12950-017-0151-x] [Citation(s) in RCA: 71] [Impact Index Per Article: 10.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 07/15/2016] [Accepted: 02/07/2017] [Indexed: 11/26/2022]
Abstract
Background Peritoneal macrophages are widely used in immunological studies. The cells can be collected under non-elicited (resident) or elicited (e.g., with Brewer thioglycollate broth injection) conditions, and their phenotype and functions differ. Recent studies have shown that macrophage phenotype and function are related to their metabolic states, and metabolic reprogramming has been an emerging concept for controlling macrophage function. In this study, we examined the metabolic state of resident and elicited macrophages and investigated how their metabolic state may affect cell function, including phagocytosis. Findings Flow cytometry showed that elicited macrophages expressed higher levels of MHC-II, LFA-1 and CD64 but lower levels of F4/80 compared to naïve resident peritoneal macrophages, suggesting a more mature and active phenotype. Elicited macrophages had significantly higher levels of phagocytic activity compared to that of resident macrophages. Metabolic studies showed that the Extracellular Acidification Rates (ECAR) and Oxygen Consumption Rates (OCR) were both significantly higher in elicited macrophages than those in resident macrophages. The treatment of macrophages with 2-Deoxy-D-glucose suppressed glycolysis and reduced phagocytosis, whereas treatment with oligomycin enhanced glycolysis and increased phagocytosis in elicited macrophages. Conclusion Naïve resident peritoneal macrophages are less metabolically active compared to elicited macrophages. Elicited macrophages had higher levels of glycolysis and oxidative phosphorylation, which may be related to their increased phagocytic capacity and higher levels of maturation and activation. Further understanding of the molecular links between metabolic pathways and cell function would be crucial to develop strategies to control macrophage function through metabolic reprogramming.
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Affiliation(s)
- Sofia Pavlou
- Centre for Experimental Medicine, School of Medicine, Dentistry & Biomedical Science, Queens University Belfast, Belfast, Northern Ireland UK
| | - Luxi Wang
- Centre for Experimental Medicine, School of Medicine, Dentistry & Biomedical Science, Queens University Belfast, Belfast, Northern Ireland UK
| | - Heping Xu
- Centre for Experimental Medicine, School of Medicine, Dentistry & Biomedical Science, Queens University Belfast, Belfast, Northern Ireland UK
| | - Mei Chen
- Centre for Experimental Medicine, School of Medicine, Dentistry & Biomedical Science, Queens University Belfast, Belfast, Northern Ireland UK
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11
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Ruffmann C, Calboli FCF, Bravi I, Gveric D, Curry LK, de Smith A, Pavlou S, Buxton JL, Blakemore AIF, Takousis P, Molloy S, Piccini P, Dexter DT, Roncaroli F, Gentleman SM, Middleton LT. Cortical Lewy bodies and Aβ burden are associated with prevalence and timing of dementia in Lewy body diseases. Neuropathol Appl Neurobiol 2015; 42:436-50. [DOI: 10.1111/nan.12294] [Citation(s) in RCA: 54] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2015] [Revised: 09/24/2015] [Accepted: 11/03/2015] [Indexed: 01/16/2023]
Affiliation(s)
- C. Ruffmann
- Neuroepidemiology and Ageing Research Unit; School of Public Health; Imperial College; London UK
- Centro Parkinson; Istituti Clinici di Perfezionamento di Milano; Milano Italy
| | - F. C. F. Calboli
- Neuroepidemiology and Ageing Research Unit; School of Public Health; Imperial College; London UK
| | - I. Bravi
- Division of Brain Sciences; Department of Medicine; Imperial College; London UK
| | - D. Gveric
- Division of Brain Sciences; Department of Medicine; Imperial College; London UK
| | - L. K. Curry
- Neuroepidemiology and Ageing Research Unit; School of Public Health; Imperial College; London UK
| | - A. de Smith
- Genomics of Common Disease; School of Public Health; Imperial College; London UK
- Department of Epidemiology and Biostatistics; University of California, San Francisco; San Francisco CA USA
| | - S. Pavlou
- Genomics of Common Disease; School of Public Health; Imperial College; London UK
- Department of Molecular Virology; Cyprus Institute of Neurology and Genetics; Nicosia Cyprus
| | - J. L. Buxton
- Section of Investigative Medicine; Department of Medicine; Imperial College; London UK
| | - A. I. F. Blakemore
- Section of Investigative Medicine; Department of Medicine; Imperial College; London UK
| | - P. Takousis
- Neuroepidemiology and Ageing Research Unit; School of Public Health; Imperial College; London UK
| | - S. Molloy
- Division of Brain Sciences; Department of Medicine; Imperial College; London UK
| | - P. Piccini
- Division of Brain Sciences; Department of Medicine; Imperial College; London UK
| | - D. T. Dexter
- Division of Brain Sciences; Department of Medicine; Imperial College; London UK
| | - F. Roncaroli
- Institute of Brain Behaviour and Mental Health; University of Manchester; Manchester UK
| | - S. M. Gentleman
- Division of Brain Sciences; Department of Medicine; Imperial College; London UK
| | - L. T. Middleton
- Neuroepidemiology and Ageing Research Unit; School of Public Health; Imperial College; London UK
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12
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Pavlou S, Astell K, Kasioulis I, Gakovic M, Baldock R, van Heyningen V, Coutinho P. Pleiotropic effects of Sox2 during the development of the zebrafish epithalamus. PLoS One 2014; 9:e87546. [PMID: 24498133 PMCID: PMC3909122 DOI: 10.1371/journal.pone.0087546] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2013] [Accepted: 12/26/2013] [Indexed: 12/01/2022] Open
Abstract
The zebrafish epithalamus is part of the diencephalon and encompasses three major components: the pineal, the parapineal and the habenular nuclei. Using sox2 knockdown, we show here that this key transcriptional regulator has pleiotropic effects during the development of these structures. Sox2 negatively regulates pineal neurogenesis. Also, Sox2 is identified as the unknown factor responsible for pineal photoreceptor prepatterning and performs this function independently of the BMP signaling. The correct levels of sox2 are critical for the functionally important asymmetrical positioning of the parapineal organ and for the migration of parapineal cells as a coherent structure. Deviations from this strict control result in defects associated with abnormal habenular laterality, which we have documented and quantified in sox2 morphants.
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Affiliation(s)
- Sofia Pavlou
- Biomedical Systems Analysis Section, Medical Developmental Genetics Section, Medical Research Council Human Genetics Unit, Medical Research Council Institute of Genetics and Molecular Medicine, University of Edinburgh, Edinburgh, United Kingdom
| | - Katy Astell
- Biomedical Systems Analysis Section, Medical Developmental Genetics Section, Medical Research Council Human Genetics Unit, Medical Research Council Institute of Genetics and Molecular Medicine, University of Edinburgh, Edinburgh, United Kingdom
| | - Ioannis Kasioulis
- Biomedical Systems Analysis Section, Medical Developmental Genetics Section, Medical Research Council Human Genetics Unit, Medical Research Council Institute of Genetics and Molecular Medicine, University of Edinburgh, Edinburgh, United Kingdom
| | - Milica Gakovic
- Biomedical Systems Analysis Section, Medical Developmental Genetics Section, Medical Research Council Human Genetics Unit, Medical Research Council Institute of Genetics and Molecular Medicine, University of Edinburgh, Edinburgh, United Kingdom
| | - Richard Baldock
- Biomedical Systems Analysis Section, Medical Developmental Genetics Section, Medical Research Council Human Genetics Unit, Medical Research Council Institute of Genetics and Molecular Medicine, University of Edinburgh, Edinburgh, United Kingdom
| | - Veronica van Heyningen
- Biomedical Systems Analysis Section, Medical Developmental Genetics Section, Medical Research Council Human Genetics Unit, Medical Research Council Institute of Genetics and Molecular Medicine, University of Edinburgh, Edinburgh, United Kingdom
| | - Pedro Coutinho
- Biomedical Systems Analysis Section, Medical Developmental Genetics Section, Medical Research Council Human Genetics Unit, Medical Research Council Institute of Genetics and Molecular Medicine, University of Edinburgh, Edinburgh, United Kingdom
- * E-mail:
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13
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Economou CN, Vasiliadou IA, Aggelis G, Pavlou S, Vayenas DV. Modeling of oleaginous fungal biofilm developed on semi-solid media. Bioresour Technol 2011; 102:9697-9704. [PMID: 21880483 DOI: 10.1016/j.biortech.2011.08.003] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/13/2011] [Revised: 07/29/2011] [Accepted: 08/01/2011] [Indexed: 05/31/2023]
Abstract
An oleaginous fungus, Mortierella isabellina, able to transform efficiently sugar to storage lipid, was used as a model microorganism which develops a biofilm structure during the semi-solid fermentation process for the production of biodiesel from sweet sorghum. A mathematical model was developed to describe the fungal oil production in M. isabellina biofilm. The model describes diffusion and consumption of sugars and nitrogen of sweet sorghum and single cell oil production in a biofilm, which grows according to the kinetics of double-substrate limitation (sugars and nitrogen) with sugar inhibition. Experimental data from a previous experimental study were used to determine the kinetic parameters of the model. Maximum biofilm thickness and the percentage of lipid inside the biofilm were estimated using the model at 1892 μm and 15%, respectively. The proposed mathematical model could prove a useful tool for designing semi-solid fermentation processes.
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Affiliation(s)
- Ch N Economou
- Department of Environmental and Natural Resources Management, University of Ioannina, G. Seferi 2, 30100 Agrinio, Greece
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14
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Economou CN, Aggelis G, Pavlou S, Vayenas DV. Single cell oil production from rice hulls hydrolysate. Bioresour Technol 2011; 102:9737-42. [PMID: 21875786 DOI: 10.1016/j.biortech.2011.08.025] [Citation(s) in RCA: 84] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/09/2011] [Revised: 07/15/2011] [Accepted: 08/04/2011] [Indexed: 05/05/2023]
Abstract
Rice hull hydrolysate was used as feedstock for microbial lipids production using the oleaginous fungus Mortierella isabellina. Kinetic experiments were conducted in C/N ratios 35, 44 and 57 and the oil accumulation into fungal biomass was 36%, 51.2% and 64.3%, respectively. A detailed mathematical model was used in order to describe the lipid accumulation process. This model was able to predict reducing sugar and nitrogen consumption, fat-free biomass synthesis and lipid accumulation. Neutral lipids constitute the predominant lipid fraction, while the major fatty acids were oleic, palmitic and linoleic acid. Fatty acids of long aliphatic chain were not detected, thus the microbial oil produced is a promising feedstock for biodiesel production.
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Affiliation(s)
- Ch N Economou
- Department of Environmental and Natural Resources Management, University of Ioannina, G. Seferi 2, 30100 Agrinio, Greece
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15
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Coutinho P, Pavlou S, Bhatia S, Chalmers KJ, Kleinjan DA, van Heyningen V. Discovery and assessment of conserved Pax6 target genes and enhancers. Genome Res 2011; 21:1349-59. [PMID: 21617155 DOI: 10.1101/gr.124115.111] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
The characterization of transcriptional networks (TNs) is essential for understanding complex biological phenomena such as development, disease, and evolution. In this study, we have designed and implemented a procedure that combines in silico target screens with zebrafish and mouse validation, in order to identify cis-elements and genes directly regulated by Pax6. We chose Pax6 as the paradigm because of its crucial roles in organogenesis and human disease. We identified over 600 putative Pax6 binding sites and more than 200 predicted direct target genes, conserved in evolution from zebrafish to human and to mouse. This was accomplished using hidden Markov models (HMMs) generated from experimentally validated Pax6 binding sites. A small sample of genes, expressed in the neural lineage, was chosen from the predictions for RNA in situ validation using zebrafish and mouse models. Validation of DNA binding to some predicted cis-elements was also carried out using chromatin immunoprecipitation (ChIP) and zebrafish reporter transgenic studies. The results show that this combined procedure is a highly efficient tool to investigate the architecture of TNs and constitutes a useful complementary resource to ChIP and expression data sets because of its inherent spatiotemporal independence. We have identified several novel direct targets, including some putative disease genes, among them Foxp2; these will allow further dissection of Pax6 function in development and disease.
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Affiliation(s)
- Pedro Coutinho
- Medical Research Council (MRC) Human Genetics Unit, Western General Hospital, Edinburgh EH4 2XU, UK.
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16
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Economou C, Aggelis G, Pavlou S, Vayenas D. Modeling of single-cell oil production under nitrogen-limited and substrate inhibition conditions. Biotechnol Bioeng 2010; 108:1049-55. [DOI: 10.1002/bit.23026] [Citation(s) in RCA: 91] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2010] [Revised: 11/18/2010] [Accepted: 11/29/2010] [Indexed: 11/11/2022]
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17
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Karanasios KA, Vasiliadou IA, Pavlou S, Vayenas DV. Hydrogenotrophic denitrification of potable water: a review. J Hazard Mater 2010; 180:20-37. [PMID: 20471745 DOI: 10.1016/j.jhazmat.2010.04.090] [Citation(s) in RCA: 165] [Impact Index Per Article: 11.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/06/2010] [Revised: 04/19/2010] [Accepted: 04/20/2010] [Indexed: 05/29/2023]
Abstract
Several approaches of hydrogenotrophic denitrification of potable water as well as technical data and mathematical models that were developed for the process are reviewed. Most of the applications that were tested for hydrogenotrophic process achieved great efficiency, high denitrification rates, and operational simplicity. Moreover, this paper reviews the variety of reactor configurations that have been used for hydrogen gas generation and efficient hydrogen delivery. Microbial communities and species that participate in the denitrification process are also reported. The variation of nitrate concentration, pH, temperature, alkalinity, carbon and microbial acclimation was found to affect the denitrification rates. The main results regarding research progress on hydrogenotrophic denitrification are evaluated. Finally, the commonly used models and simulation approaches are discussed.
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Affiliation(s)
- K A Karanasios
- Department of Environmental and Natural Resources Management, University of Ioannina, Seferi 2, 30100 Agrinio, Greece
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18
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Dikshitulu S, Baltzis BC, Lewandowski GA, Pavlou S. Competition between two microbial populations in a sequencing fed-batch reactor: theory, experimental verification, and implications for waste treatment applications. Biotechnol Bioeng 2010; 42:643-56. [PMID: 18613087 DOI: 10.1002/bit.260420513] [Citation(s) in RCA: 64] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
Competition between two microbial populations for a single pollutant (phenol) was studied in a sequencing fed-batch reactor (SFBR). A mathematical model describing this system was developed and tested experimentally. It is based on specific growth rate expressions revealed from pure culture batch experiments. The species employed were Pseudomonas putida (ATCC 17514) and Pseudomonas resinovorans (ATCC 14235). It was found that both species biodegrade phenol following inhibitory kinetics which can be described by Andrews' expression. The model predicts that the dynamics of a SFBR, and the kinetics of biodegradation, result in a complex set of operating regimes in which neither species, only one species, or both species can survive at steady cycle. The model also predicts the existence of multiple outcomes, achievable from different start-up conditions, in some domains of the operating parameter space. Experimental results confirmed the model predictions. There was excellent agreement between predicted and measured concentrations of phenol, total biomass, and the biomass of each individual species. This study shows how serious discrepancies can arise in scale-up of biodegradation data if population dynamics are not taken into account. It also further confirms experimentally the theory of microbial competition in periodically forced bioreactors.
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Affiliation(s)
- S Dikshitulu
- Department of Chemical Engineering, Chemistry, and Environmental Science, New Jersey Institute of Technology, Newark, New Jersey 07102, USA
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19
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Economou CN, Makri A, Aggelis G, Pavlou S, Vayenas DV. Semi-solid state fermentation of sweet sorghum for the biotechnological production of single cell oil. Bioresour Technol 2010; 101:1385-8. [PMID: 19781936 DOI: 10.1016/j.biortech.2009.09.028] [Citation(s) in RCA: 81] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/05/2009] [Revised: 09/03/2009] [Accepted: 09/08/2009] [Indexed: 05/08/2023]
Abstract
A semi-solid fermentation process for the production of biodiesel from sweet sorghum is introduced. The microorganism used is the oleaginous fungus Mortierella isabellina, which is able to transform efficiently sugar to storage lipid. Kinetic experiments were performed at various water content percentages. The fungus consumed simultaneously sugars and nitrogen contained in sorghum and after nitrogen depletion the biomass growth was completed and oil accumulation began. Water content of 92% presented the highest oil efficiency of 11 g/100 g dry weight of substrate. The semi-solid process is shown to have certain advantages compared to liquid cultures or solid-state fermentation and gives oil of high quality.
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Affiliation(s)
- Ch N Economou
- Department of Environmental and Natural Resources Management, University of Ioannina, G. Seferi 2, 30100 Agrinio, Greece
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20
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Vasiliadou IA, Karanasios KA, Pavlou S, Vayenas DV. Experimental and modelling study of drinking water hydrogenotrophic denitrification in packed-bed reactors. J Hazard Mater 2009; 165:812-824. [PMID: 19054612 DOI: 10.1016/j.jhazmat.2008.10.067] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/09/2008] [Revised: 10/11/2008] [Accepted: 10/15/2008] [Indexed: 05/27/2023]
Abstract
The aim of this work was to study hydrogenotrophic denitrification in packed-bed reactors under draw-fill and continuous operation. Three bench-scale packed-bed reactors with gravel in different sizes (mean diameter 1.75, 2.41 and 4.03 mm) as support media were used, in order to study the effect of particle size on reactors performance. The maximum denitrification rate achieved under draw-fill operation was 4.4 g NO(3)(-)-N/ld for the filter with gravel of 2.41 mm. This gravel size was chosen to perform experiments under continuous operation. Feed NO(3)(-)-N concentrations and hydraulic loadings (HL) ranged between 20-200mg/l and 5.7-22.8m(3)/m(2)d, respectively. A comparison between the two operating modes showed that, for low HL the draw-fill operation achieved higher denitrification rates, while for high HL and intermediate feed concentrations (40-60 mg NO(3)(-)-N/l) the continuous operation achieved higher denitrification rates (4.67-5.65 g/ld). Finally, experiments with three filters in series (with gravels of 4.03, 2.41 and 1.75 mm mean diameter) were also performed under continuous operation. The maximum denitrification rate achieved was 6.2 g NO(3)(-)-N/ld for feed concentration of 340 mg/l and HL of 11.5m(3)/m(2)d. A model, which describes denitrification in packed-bed reactors, was also developed. The model predicts the concentration profiles of NO(3)(-)-N along filter height, in draw-fill as well as in continuous operation, satisfactorily.
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Affiliation(s)
- I A Vasiliadou
- Department of Environmental and Natural Resources Management, University of Ioannina, Agrinio, Greece
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21
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Vasiliadou I, Pavlou S, Vayenas D. Dynamics of a chemostat with three competitive hydrogen oxidizing denitrifying microbial populations and their efficiency for denitrification. Ecol Modell 2009. [DOI: 10.1016/j.ecolmodel.2009.02.009] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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22
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Kavadia A, Vayenas D, Pavlou S, Aggelis G. Dynamics of free-living nitrogen-fixing bacterial populations and nitrogen fixation in a two-prey–one-predator system. Ecol Modell 2008. [DOI: 10.1016/j.ecolmodel.2008.07.018] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
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Sgountzos I, Pavlou S, Paraskeva C, Payatakes A. Growth kinetics of Pseudomonas fluorescens in sand beds during biodegradation of phenol. Biochem Eng J 2006. [DOI: 10.1016/j.bej.2006.03.005] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
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26
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Vasiliadou IA, Siozios S, Papadas IT, Bourtzis K, Pavlou S, Vayenas DV. Kinetics of pure cultures of hydrogen-oxidizing denitrifying bacteria and modeling of the interactions among them in mixed cultures. Biotechnol Bioeng 2006; 95:513-25. [PMID: 16758460 DOI: 10.1002/bit.21031] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.9] [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: 11/07/2022]
Abstract
In this study we report the isolation of four denitrifying bacteria from a batch reactor, where the progress of hydrogenotrophic denitrification was examined. Only three of the strains had the ability to use hydrogen as electron donor. In the present work, kinetic batch experiments were carried out in order to study the dynamic characteristics of pure and defined mixed cultures of hydrogen-oxidizing denitrifying bacteria, under anoxic conditions, in a defined synthetic medium, in the presence of nitrates. Kinetic models were developed and the kinetic parameters were determined from the batch experiments for each bacterium separately. The behavior of mixed cultures and the interactions between the bacteria were described using kinetic models based on the kinetic models developed for each bacterium separately and their predictions were compared with the results from mixed culture experiments. The mathematical models that were developed and validated in the present work are capable of describing the behavior of the bacteria in pure and mixed cultures, and in particular, the kinetics of nitrate and nitrite reduction and cell growth.
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Affiliation(s)
- I A Vasiliadou
- Department of Environmental and Natural Resources Management, University of Ioannina, Seferi 2, 30100 Agrinio, Greece
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27
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Vayenas D, Aggelis G, Tsagou V, Pavlou S. Dynamics of a two-prey–one-predator system with predator switching regulated by a catabolic repression control-like mode. Ecol Modell 2005. [DOI: 10.1016/j.ecolmodel.2005.01.032] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
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28
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Abstract
We analyze a mathematical model of a simple food web consisting of one predator and two prey populations in a chemostat. Monod's model is employed for the dependence of the specific growth rates of the two prey populations on the concentration of the rate-limiting substrate and a generalization of Monod's model for the dependence of the specific growth rate of the predator on the concentrations of the prey populations. We use numerical bifurcation techniques to determine the effect of the operating conditions of the chemostat on the dynamics of the system and construct its operating diagram. Chaotic behavior resulting from successive period doublings is observed. Multistability phenomena of coexistence of steady and periodic states at the same operating conditions are also found.
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Affiliation(s)
- D V Vayenas
- Department of Chemical Engineering, University of Patras, FORTH, Greece
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29
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Abstract
We study a model of three microbial populations competing for three complementary nutrients in a single chemostat. By using methods of numerical bifurcation theory we analyze the model equations and determine the effect of the model parameters on the dynamics of the system. The main question to be answered is whether there exist conditions under which the three populations can coexist in a stable state in the chemostat. The analysis shows that coexistence can be obtained as a stable steady state but also as a stable periodic state for a wide range of operating conditions of the chemostat.
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Affiliation(s)
- D V Vayenas
- Department of Chemical Engineering, University of Patras, Greece
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30
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Abstract
The operating diagram of a bioreactor is an illustrative way to present the effect that the operating conditions have on its long-term behavior. It can be constructed if a mathematical model of the bioreactor is available. The procedure for constructing the operating diagram consists in analyzing the dynamic behavior of the system of the differential equations of the model. Some methods are described that can be used in computing operating diagrams of bioreactors. They are based on numerical bifurcation techniques for systems of differential equations. Both cases of bioreactors with constant and periodically varying operating conditions are considered.
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Affiliation(s)
- S Pavlou
- Department of Chemical Engineering, University of Patras, Greece.
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31
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Thomopoulos NA, Vayenas DV, Pavlou S. On the coexistence of three microbial populations competing for two complementary substrates in configurations of interconnected chemostats. Math Biosci 1998; 154:87-102. [PMID: 9949649 DOI: 10.1016/s0025-5564(98)10047-0] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [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: 11/30/2022]
Abstract
We examine the question of coexistence of three microbial populations competing for two complementary rate-limiting substrates in configurations of interconnected chemostats. It is known that coexistence of two populations competing for two rate-limiting substrates is possible in a single chemostat, but coexistence is not possible when three populations are involved. We examine whether coexistence of three populations becomes possible by considering configurations of two or three interconnected chemostats, thus allowing for effects of spatial heterogeneity. Computational analysis of the model equations indicates that in the case of two chemostats coexistence is possible only for specific discrete parameter values where the system is structurally unstable and therefore the coexistence state is not practically attainable, whereas in the case of three chemostats coexistence is possible for a whole range of parameter values where the system is structurally stable and therefore the coexistence state can be realized in practice.
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Affiliation(s)
- N A Thomopoulos
- Department of Chemical Engineering, University of Patras, Greece
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32
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Abstract
It is known that, when two microbial populations competing for a single rate-limiting nutrient are grown in a spatially uniform environment, such as a single chemostat, with competition being the only interaction between them, they cannot coexist, but eventually one of the two populations prevails and the other becomes extinct. Spatial heterogeneity has been suggested as a means of obtaining coexistence of the two populations. A configuration of two interconnected chemostats is a simple model of a spatially heterogeneous environment. It has been shown that, when Monod's model is used for the specific growth rates of the two populations, steady-state coexistence can be obtained in such systems for wide ranges of operating conditions. In the present work, we study a model of microbial competition in configurations of interconnected chemostats and we show that, if a substrate inhibition model is used for the specific growth rates of the two populations, coexistence in a periodic state is also possible. The analysis of the model is done by numerical bifurcation theory methods.
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Affiliation(s)
- P Lenas
- Department of Chemical Engineering, University of Patras, Greece
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33
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Sakellariou M, Pavlou S, Tzeferacos A, Michalopoulos J, Kastoras A, Christopoulos J, Papalouka M, Xidias G, Kiessling A. P-100. Outcome of insemination with high sperm concentrations for brief periods of time. Hum Reprod 1997. [DOI: 10.1093/humrep/12.suppl_2.168-a] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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34
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Abstract
Coexistence of three microbial populations engaged in pure and simple competition is not possible in a chemostat with time-invariant operating conditions under any circumstances. It is shown that by periodic variation of the chemostat dilution rate it is possible to obtain a stable coexistence state of all three populations in the chemostat. This is accomplished by performing a numerical bifurcation analysis of a mathematical model of the system and by determining its dynamic behavior with respect to its operating parameters. The coexistence state obtained in the periodically operated chemostat is usually periodic, but cases of quasi-periodic and chaotic behavior are also observed.
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Affiliation(s)
- P Lenas
- Department of Chemical Engineering, University of Patras, Greece
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Abstract
Predator-prey systems in continuously operated chemostats exhibit sustained oscillations over a wide range of operating conditions. When two such chemostats interact through flow exchange, the interplay of the oscillation frequencies gives rise to a wealth of dynamic behavior patterns. Using numerical bifurcation techniques, we perform a detailed computational study of these patterns and the transitions between them as the coupling strength and relative frequencies of the two chemostats vary. We concentrate on certain strong resonance phenomena between the two frequencies as well as their mutual extinction and provide a representative sampling of possible phase portraits for our model system. Our observations corroborate recent mathematical results and case studies of coupled nonlinear chemical oscillators in which regions of mutual extinction as well as the Arnol'd structure for two-parameter families of maps of the plane have been observed. We highlight certain unexpected features of the operating diagram discovered through our computational study and discuss their implication for the dynamic response of the chemostat system.
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Affiliation(s)
- M A Taylor
- Department of Chemical Engineering, Princeton University, New Jersey
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36
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Abstract
It is well known that when two microbial populations competing for a single rate-limiting nutrient are grown in a chemostat with time-invariant inputs, with competition being the only interaction between them, they cannot coexist, but eventually one of the two populations prevails and the other becomes extinct. It has been suggested that periodic variation of one of the chemostat's operating parameters can stabilize the coexistence state of the two microbial populations. A systematic numerical study of the model equations describing microbial competition in a chemostat with periodically varying dilution rate is performed, and it is shown that coexistence of the competing microbial populations is obtained for a wide range of operating conditions. The coexistence state is usually in the form of limit cycle oscillations. However, cases of chaotic behavior resulting from successive period doublings and quasi-periodicity are also observed.
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Affiliation(s)
- P Lenas
- Department of Chemical Engineering, University of Patras, Greece
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Pavlou S, Kevrekidis IG. Microbial predation in a periodically operated chemostat: a global study of the interaction between natural and externally imposed frequencies. Math Biosci 1992; 108:1-55. [PMID: 1550993 DOI: 10.1016/0025-5564(92)90002-e] [Citation(s) in RCA: 47] [Impact Index Per Article: 1.5] [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: 12/27/2022]
Abstract
Predator-prey systems in continuously operated chemostats exhibit sustained oscillations over a wide range of operating conditions. When the chemostat is operated periodically, the interaction of the natural oscillation frequency with the external forcing gives rise to a wealth of dynamic behavior patterns. Using numerical bifurcation techniques, we perform a detailed computational study of these patterns and the transitions (local and especially global) between them as the amplitude and frequency of the forcing vary. The transition from low-forcing-amplitude quasiperiodicity to entrainment of the chemostat behavior by strong forcing (involving the concerted closing of resonance horns) is analyzed. We concentrate on certain strong resonance phenomena between the two frequencies and provide an extensive atlas of computed phase portraits for our model system. Our observations corroborate recent mathematical results and case studies of periodically forced chemical oscillators. In particular, the existence and relative succession of several distinct types of global bifurcations resulting in chaotic transients and multistability are studied in detail. The location in the operating diagram of several key codimension 2 local bifurcations of periodic solutions is computed, and their interaction with an interesting feature we name "real-eigenvalues horns" is examined.
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Affiliation(s)
- S Pavlou
- Department of Chemical Engineering, University of Patras, Greece
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Pavlou S, Vayenas C, Dassios G. Comments on optimal catalyst activity profiles in pellets—VIII. General nonisothermal reacting systems with arbitrary kinetics. Chem Eng Sci 1991. [DOI: 10.1016/0009-2509(91)85041-u] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
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40
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Abstract
A mathematical model for an ideal chemostat in which one microbial population feeds on another and where Monod's model is used for the specific growth rates of both populations predicts a less stable behavior for the system than the one observed experimentally. Various factors have been proposed as being the reason for the increased stability of such systems. In this work, the effect of spatial heterogeneity on the dynamics of the microbial feeding interaction is studied. It is concluded that spatial heterogeneity has a stabilizing effect on the system. This effect combined with other factors could be the reason for the increased stability observed in systems where a microbial feeding interaction occurs.
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Affiliation(s)
- E Tsangaropoulou
- Institute of Chemical Engineering and High Temperature Chemical Processes and Department of Chemical Engineering, University of Patras, GR-26110 Patras, Greece
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Pavlou S, Kevrekidis IG, Lyberatos G. On the coexistence of competing microbial species in a chemostat under cycling. Biotechnol Bioeng 1990; 35:224-32. [DOI: 10.1002/bit.260350303] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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Mortola JF, Sathanandan M, Pavlou S, Dahl KD, Hsueh AJ, Rivier J, Vale W, Yen SS. Suppression of bioactive and immunoreactive follicle-stimulating hormone and luteinizing hormone levels by a potent gonadotropin-releasing hormone antagonist: pharmacodynamic studies. Fertil Steril 1989; 51:957-63. [PMID: 2498133] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
Dose-dependent gonadotropin suppression by a potent gonadotropin-releasing hormone (GnRH) antagonist, Nal1 Glu6 [( Ac-D2Nal1,D4ClPhe2,D3Pal3,Arg5,DGlu(AA)6,- DAla10]GnRH), was determined in five postmenopausal women by frequent sampling for immunoreactive luteinizing hormone (I-LH) and immunoreactive follicle stimulating hormone (I-FSH) for 72 hours after single intramuscular (IM) injections of 10, 50, 150, and 300 micrograms/kg. Bioactive (B) LH and B-FSH also were measured after the IM administration of the 50-micrograms/kg dose. Serum levels of Nal1 Glu6 were determined by a radioreceptor assay for the first 24 hours after the 50-micrograms/kg IM dose and in three women after a 10-micrograms/kg intravenous (IV) dose. While the disappearance rate of serum Nal1 Glu6 after a 10-micrograms/kg IV injection was rapid, gonadotropin suppression persisted longer than detectable serum levels. In contrast, after a 50-micrograms/kg IM injection, the decline from peak circulating levels was slower, contributing to its longer duration of action (greater than 24 hours). All IM doses tested resulted in a similar 51% to 63% decrease in I-LH, which was maximal by 8 hours. The duration of action was dose-dependent, with decreased levels lasting up to 72 hours at the 300-micrograms/kg dose. While decline of I-FSH was smaller (14% to 33%), the duration of suppression was also dose-dependent, although the nadir occurs later (8 to 9 hours after administration) and suppression lasted longer (72 hours at the 150-micrograms/kg dose). The reduction of B-LH was greater than that of I-LH and the suppression of B-FSH also was greater than that of I-FSH.(ABSTRACT TRUNCATED AT 250 WORDS)
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Affiliation(s)
- J F Mortola
- Department of Reproductive Medicine, University of California, San Diego, School of Medicine, La Jolla 92093
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Sambanis A, Pavlou S, Fredrickson AG. Coexistence of bacteria and feeding ciliates: Growth of bacteria on autochthonous substrates as a stabilizing factor for coexistence. Biotechnol Bioeng 1987; 29:714-28. [DOI: 10.1002/bit.260290608] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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Abstract
The effects of the potent GnRH antagonist [Ac-D-NAL(2)1, 4F-D-Phe2, D-Trp3, D-Arg6]-GnRH (GnRH-A), on ovulation in mature rats and rabbits and on serum LH and FSH levels in ovariectomized rats, rabbits and mice were investigated. Dose-response studies showed that 1 microgram (4 micrograms/kg) of GnRH-A was sufficient to inhibit ovulation completely in cycling rats, while 500 micrograms (135 micrograms/kg) were required to inhibit mating induced ovulation in 8 of 11 rabbits. Two of the 3 rabbits which ovulated in spite of the antagonist treatment had delayed LH surges. The mean LH peak of these 3 rabbits was significantly (p less than 0.001) lower than that of controls. Pituitary response to GnRH-A, as measured by plasma gonadotropin levels following GnRH-A treatment in ovariectomized rabbits, rats and mice showed highest sensitivity of the rat to the inhibitory effects of the antagonist. Serum FSH levels were slightly suppressed in rats, but remained undiminished in rabbits and mice. The difference in the response of the three species to the antipituitary effects of GnRH-A is most likely due to differences in the affinity of the pituitary GnRH receptor to the antagonist.
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Wang NG, Sundaram K, Pavlou S, Rivier J, Vale W, Bardin CW. Mice are insensitive to the antitesticular effects of luteinizing hormone-releasing hormone agonists. Endocrinology 1983; 112:331-5. [PMID: 6291919 DOI: 10.1210/endo-112-1-331] [Citation(s) in RCA: 57] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Abstract
Treatment of male rats with [(imBzl)-D-His6, Pro9-NEt]LHRH or [D-Trp6,Pro9-NEt]LHRH, potent agonists of LHRH, led to a marked decrease in serum testosterone levels and a reduction in testicular LH receptor concentration. Similar treatment of mice showed that they were resistant to the antitesticular effects of the LHRH agonists. To further explore the differences between rats and mice, the direct antitesticular effects of these peptides were investigated in hypophysectomized animals. Hypophysectomized rats and mice were given ovine FSH (50 micrograms), with or without a LHRH agonist (10 micrograms), daily for 5 days. On day 6, the testicular steroidogenic response to hCG was studied. In these studies the in vivo as well as the in vitro steroidogenic response of rat testes to hCG were inhibited by the LHRH analogs. In contrast, pretreatment of mice with the LHRH analogs did not affect their testicular steroidogenic response. Binding studies with the [125I]LHRH analog demonstrated receptors for this peptide on Leydig cells from adult rats. Receptors for LHRH were not, however, detectable on murine Leydig cells. These results suggest that one of the reasons for the lack of an antitesticular effect of LHRH agonists in mice may be due to the inability of these peptides to have a direct effect on testes and may relate to a lack of LHRH receptors.
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Benelli C, Durbin P, Pavlou S, Michel O, Michel R. [Effects of thyroidectomy on the limiting step of steroid biosynthesis in the adrenal cortex and testis of the rat]. Pathol Biol (Paris) 1980; 28:371-372. [PMID: 6994041] [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: 05/21/2023]
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Batrinos ML, Panitsa-Faflia C, Pitoulis S, Pavlou S, Piaditis G, Alexandridis T, Liappi C. The clinical features of the menopause and its relation to the length of pregnancies and lactation. Maturitas 1979; 1:261-8. [PMID: 551236 DOI: 10.1016/0378-5122(79)90016-1] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
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