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Martín-Sánchez F, Diamond C, Zeitler M, Gomez AI, Baroja-Mazo A, Bagnall J, Spiller D, White M, Daniels MJD, Mortellaro A, Peñalver M, Paszek P, Steringer JP, Nickel W, Brough D, Pelegrín P. Inflammasome-dependent IL-1β release depends upon membrane permeabilisation. Cell Death Differ 2016; 23:1219-31. [PMID: 26868913 PMCID: PMC4946890 DOI: 10.1038/cdd.2015.176] [Citation(s) in RCA: 185] [Impact Index Per Article: 23.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2015] [Revised: 12/03/2015] [Accepted: 12/22/2015] [Indexed: 12/03/2022] Open
Abstract
Interleukin-1β (IL-1β) is a critical regulator of the inflammatory response. IL-1β is not secreted through the conventional ER–Golgi route of protein secretion, and to date its mechanism of release has been unknown. Crucially, its secretion depends upon the processing of a precursor form following the activation of the multimolecular inflammasome complex. Using a novel and reversible pharmacological inhibitor of the IL-1β release process, in combination with biochemical, biophysical, and real-time single-cell confocal microscopy with macrophage cells expressing Venus-labelled IL-1β, we have discovered that the secretion of IL-1β after inflammasome activation requires membrane permeabilisation, and occurs in parallel with the death of the secreting cell. Thus, in macrophages the release of IL-1β in response to inflammasome activation appears to be a secretory process independent of nonspecific leakage of proteins during cell death. The mechanism of membrane permeabilisation leading to IL-1β release is distinct from the unconventional secretory mechanism employed by its structural homologues fibroblast growth factor 2 (FGF2) or IL-1α, a process that involves the formation of membrane pores but does not result in cell death. These discoveries reveal key processes at the initiation of an inflammatory response and deliver new insights into the mechanisms of protein release.
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Affiliation(s)
- F Martín-Sánchez
- Grupo de Inflamación Molecular, Centro de Investigación Biomédica en Red en el Área Temática de Enfermedades Hepáticas y Digestivas, Hospital Clínico Universitario Virgen de la Arrixaca, Instituto Murciano de Investigación Biosanitaria (IMIB-Arrixaca), Murcia, Spain
| | - C Diamond
- Faculty of Life Sciences, University of Manchester, Manchester, UK.,Singapore Immunology Network (SIgN), Agency for Science Technology and Research (A*STAR), Singapore
| | - M Zeitler
- Heidelberg University Biochemistry Center, Heidelberg, Germany
| | - A I Gomez
- Grupo de Inflamación Molecular, Centro de Investigación Biomédica en Red en el Área Temática de Enfermedades Hepáticas y Digestivas, Hospital Clínico Universitario Virgen de la Arrixaca, Instituto Murciano de Investigación Biosanitaria (IMIB-Arrixaca), Murcia, Spain
| | - A Baroja-Mazo
- Grupo de Inflamación Molecular, Centro de Investigación Biomédica en Red en el Área Temática de Enfermedades Hepáticas y Digestivas, Hospital Clínico Universitario Virgen de la Arrixaca, Instituto Murciano de Investigación Biosanitaria (IMIB-Arrixaca), Murcia, Spain
| | - J Bagnall
- Faculty of Life Sciences, University of Manchester, Manchester, UK
| | - D Spiller
- Faculty of Life Sciences, University of Manchester, Manchester, UK
| | - M White
- Faculty of Life Sciences, University of Manchester, Manchester, UK
| | - M J D Daniels
- Faculty of Life Sciences, University of Manchester, Manchester, UK
| | - A Mortellaro
- Singapore Immunology Network (SIgN), Agency for Science Technology and Research (A*STAR), Singapore
| | - M Peñalver
- Probelte Biotechnology, S.L., Murcia, Spain
| | - P Paszek
- Faculty of Life Sciences, University of Manchester, Manchester, UK
| | - J P Steringer
- Heidelberg University Biochemistry Center, Heidelberg, Germany
| | - W Nickel
- Heidelberg University Biochemistry Center, Heidelberg, Germany
| | - D Brough
- Faculty of Life Sciences, University of Manchester, Manchester, UK
| | - P Pelegrín
- Grupo de Inflamación Molecular, Centro de Investigación Biomédica en Red en el Área Temática de Enfermedades Hepáticas y Digestivas, Hospital Clínico Universitario Virgen de la Arrixaca, Instituto Murciano de Investigación Biosanitaria (IMIB-Arrixaca), Murcia, Spain.,Faculty of Life Sciences, University of Manchester, Manchester, UK
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Davies L, Spiller D, White MRH, Grierson I, Paraoan L. PERP expression stabilizes active p53 via modulation of p53-MDM2 interaction in uveal melanoma cells. Cell Death Dis 2011; 2:e136. [PMID: 21451571 PMCID: PMC3101815 DOI: 10.1038/cddis.2011.19] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.3] [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] [Indexed: 12/22/2022]
Abstract
The activation and regulation of target genes by the tumour-suppressor p53 dictates the fate of a cell, with cell cycle arrest or apoptosis being two distinct outcomes. PERP (p53 apoptosis effector related to PMP-22), a p53 transcriptional target, is induced specifically during apoptosis but not cell cycle arrest. Downregulation of PERP is associated with the aggressive, monosomy 3-type of uveal melanoma (UM), the most common primary intraocular tumour in adults, and increased PERP expression has a pro-apoptotic effect in UM cells. Here, we identify a novel effect of PERP expression, as elevated PERP protein positively influences active levels of its own transcriptional regulator, p53. Using fluorescent fusion proteins of PERP, p53 and MDM2, we demonstrate in single living UM cells that PERP expression significantly enhances p53 activity and its nuclear localization, increases p53-dependent transcription (including that of MDM2) while allowing oscillatory nucleo-cytoplasmic shuttling of p53/MDM2 complexes. Phosphorylation of p53 serine residues that interfere with the interaction between p53 and its negative regulator MDM2 and enhance pro-apoptotic gene transcription also occurs subsequent to PERP expression. These results implicate a role for PERP in amplifying functional p53 levels that promote p53-dependent apoptosis, and reveal a potential target for exploitation in enhancing p53 activity.
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Affiliation(s)
- L Davies
- Department of Eye and Vision Sciences, Institute of Ageing and Chronic Disease, University of Liverpool, Liverpool, UK
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3
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Astorri E, Bombardieri M, Corsiero E, Gabba S, Barone F, Proctor G, Pitzalis C, Bowman SJ, St Pierre Y, Sutcliffe N, Isenberg DA, Goldblatt F, Price E, Hamburger J, Richards A, Rauz S, Regan M, Jones A, Rigby S, Mulherin D, Clarke A, Ong V, Nihtyanova S, Black C, Denton C, Barnes T, Spiller D, Anderson M, Edwards S, Moots R, Gamal M, Zaki E, Khaled HF, Abdul-Aziz OA, Shaaban AA, Abu Senna H, Bishop VL, Herrick A, Wragg E, Ioannou Y, Zhang JY, Passam FH, Rahgozar S, Qi JC, Giannakopoulos B, Qi M, Yu P, Yu DM, Hogg PJ, Krilis SA, Hopkins CW, Spiers LR, Bhagat SS, Ostor AJ, Hall FC. Concurrent Oral 10 - Connective Tissue Disease [OP65-OP72]: OP65. Molecular and Cellular Evolution of Functional Tertiary Lymphoid Structures in Salivary Glands of NOD Mice. Rheumatology (Oxford) 2010. [DOI: 10.1093/rheumatology/keq710] [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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4
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Spiller D, Mirtelli C, Losi P, Briganti E, Sbrana S, Counoupas S, Kull S, Tonlorenzi S, Soldani G. In vitro evaluation of the PEtU-PDMS material immunocompatibility: the influence of surface topography and PDMS content. J Mater Sci Mater Med 2009; 20:2511-2520. [PMID: 19756971 DOI: 10.1007/s10856-009-3823-0] [Citation(s) in RCA: 7] [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: 12/16/2008] [Accepted: 07/14/2009] [Indexed: 05/28/2023]
Abstract
The aim of the present work is to evaluate the in vitro immunocompatibility of an elastomeric material with feasible applications in the cardiovascular field. In particular, since it is well known that surface chemistry and topography play a key role in the foreign body response, their influence on human monocytes was evaluated. The material, constituted by a poly(ether)urethane (PEtU) and a polydimethylsiloxane (PDMS), was synthesized to manufacture films and small-diameter vascular grafts with three different surface topographical features, smooth, rough and porous, and siloxane rates, 10, 30 and 40. Human THP-1 monocytes have been cultured for 72 h on the films and human blood has been circulating for 2 h into the grafts to assess leukocyte adhesion and cytokine releases. Materials extracts were utilized to evaluate monocyte apoptosis. Smooth films showed lower cell adhesion degrees than rough and porous ones. All the PEtU-PDMS (poly(ether)urethane-polydimethylsiloxane) films and vascular grafts induced a narrow inflammatory response, as demonstrated by slight cytokine secretion levels, in particular samples with the highest PDMS contents (30 and 40%) induced the lowest IL-1b secretion. Moreover, an absence of monocyte apoptosis advises that the negligible release values have not to be ascribed to material toxicity. In the end, surface topography showed to affect only monocyte adhesion while siloxane content the cytokine release. Therefore, the possibility to modify the above tested parameters during material synthesis and manufacture could allow to bound the inflammatory potency of the PEtU-PDMS devices and render them excellent candidates for cardiovascular reconstruction.
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Affiliation(s)
- D Spiller
- Istituto di Fisiologia Clinica del Consiglio Nazionale delle Ricerche (IFC-CNR), Ospedale G. Pasquinucci, Massa, Italy.
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5
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Abstract
Faced with limited water supply options in the longer term and the worst drought on record in the short term, the Queensland Government is constructing the Western Corridor Recycled Water Project which will supply up to 182 ML/day of purified recycled water for industrial and potable purposes. The project is one of a suite of capital works projects in progress which in the longer term will supply up to 10% of the region's potable water supply.
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Affiliation(s)
- W H Traves
- GHD Pty Ltd., 201 Charlotte Street, Brisbane, Queensland, Australia.
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6
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Farneti PA, Sbrana S, Spiller D, Cerillo AG, Santarelli F, Di Dario D, Del Sarto PA, Glauber M. Reduction of blood coagulation and monocyte-platelet interaction following the use of a minimal extracorporeal circulation system (Synergy®) in coronary artery bypass grafting (CABG). Perfusion 2008; 23:49-56. [DOI: 10.1177/0267659108091336] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Cardiovascular surgery with cardiopulmonary bypass (CPB) induces activation of blood coagulation and systemic inflammation involved in post-operative complications. Our study evaluated the impact of the minimal extracorporeal circulation (mini-CPB) system (Synergy®, Sorin Group) on these functional aspects. Twenty patients were randomly assigned to standard CPB (n=10) or to Synergy (n=10). Platelet expression of PAC-1, and monocyte/granulocyte-platelet conjugates were evaluated by flow cytometry. A leukocyte-platelet adhesion index was calculated after cell number normalization. ELISAs were performed to measure IL-6 and TNF-α, thrombin-antithrombin III complexes (TAT), prothrombin fragments (F1+2), β-thromboglobulin (β-TG) and sP-selectin (sCD62P). Blood samples were drawn at the time of anesthesia (T1), at the end of CPB (T2), and at 4 (T3) and 24 hours (T4) after weaning from CPB. All patients were similar for clinical characteristics. When compared to standard CPB, the Synergy showed lower levels of the monocyte-platelet adhesion index at T2 (0.023 ± 0.005 vs 0.063 ± 0.013, P = 0.0092) and T4 (0.031 ± 0.003 vs 0.055 ± 0.005, P = 0.0017), TAT complexes at T2 (27.175 ± 5.967 vs 86.592 ± 5.415, P = 0.0005) and T3 (26.977 ± 2.468 vs 45.146 ± 4.365, P = 0.0041), F1+2 fragments at T2 (2.222 ± 0.226 vs 4.249 ± 0.292, P = 0.0009), and sP-selectin at T3 (115.17 ± 19.623 vs 169.554 ± 19.709, P = 0.0703) and T4 (108.542 ± 6.429 vs 140.799 ± 14.771, P = 0.0833). In summary, the Synergy exhibited a lower post-operative activation of blood coagulation, together with a reduced interaction between circulating monocytes and platelets.
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Affiliation(s)
- PA Farneti
- Cardiac Surgery Department, "G. Pasquinucci" Hospital, Massa (MS)- Italy
| | - S Sbrana
- Laboratory Department (Flow Cytometry Unit), "G.Pasquinucci" Hospital, Massa (MS) - Italy
| | - D Spiller
- Laboratory Department (Flow Cytometry Unit), "G.Pasquinucci" Hospital, Massa (MS) - Italy
| | - AG Cerillo
- Cardiac Surgery Department, "G. Pasquinucci" Hospital, Massa (MS)- Italy
| | - F Santarelli
- Cardiac Surgery Department, "G. Pasquinucci" Hospital, Massa (MS)- Italy
| | - D Di Dario
- Anesthesiology Department, "G. Pasquinucci" Hospital, Massa (MS) - Italy
| | - PA Del Sarto
- Anesthesiology Department, "G. Pasquinucci" Hospital, Massa (MS) - Italy
| | - M Glauber
- Cardiac Surgery Department, "G. Pasquinucci" Hospital, Massa (MS)- Italy
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7
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Howard MR, Spiller D, Reed JE, McNamee C, White M, Moss DJ. No barrier to diffusion between cell soma and neurite membranes in sympathetic neurons for a GPI-anchored glycoprotein. Mol Cell Neurosci 2003; 24:296-306. [PMID: 14572454 DOI: 10.1016/s1044-7431(03)00165-9] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [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: 11/15/2022] Open
Abstract
As neurons extend their axons, it is thought that newly synthesised membrane components travel in vesicles along the axon, fuse with the growth cone membrane, and diffuse back along the axonal membrane. However, it is difficult to explain how axons continue to be populated with membrane proteins as they extend in length. To investigate this problem, we have used a CEPU-green fluorescent protein (GFP) chimeric protein to study the site of insertion of new glycosyl phosphatidyl inositol (GPI)-anchored glycoproteins and their subsequent behaviour in chick dorsal root ganglia (DRG) neurons. Infection of cultures grown for 24 h revealed rapid expression of CEPU-GFP over the whole surface of the neuron, more rapidly than could be accounted for by diffusion from the growth cone, and fluorescence intensity was uniform along the length of the neurite. Photobleaching experiments of neurite membrane revealed that recovery of fluorescence was due to diffusion from adjacent membranes and there was no evidence for membrane flow in either direction. Photobleaching of membrane adjacent to the cell body also showed rapid recovery, with chimera diffusing both from cell body membrane and the distal neurite membrane into the bleached area. These results suggest there is no barrier to diffusion between the cell body and neurite membrane in DRG and sympathetic neurons cultured for 1 or 2 days in vitro. We propose that the neurite is populated by newly synthesised chimera by diffusion from both regions. This situation may also occur in neurons in the early stages of extending axons in vivo prior to polarisation and the development of the dendritic field.
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Affiliation(s)
- M R Howard
- Department of Human Anatomy and Cell Biology, The University of Liverpool, Liverpool, UK
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8
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Burdyga G, Spiller D, Morris R, Lal S, Thompson DG, Saeed S, Dimaline R, Varro A, Dockray GJ. Expression of the leptin receptor in rat and human nodose ganglion neurones. Neuroscience 2002; 109:339-47. [PMID: 11801369 DOI: 10.1016/s0306-4522(01)00474-2] [Citation(s) in RCA: 104] [Impact Index Per Article: 4.7] [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: 10/18/2022]
Abstract
There is evidence for interactions between leptin and cholecystokinin in controlling food intake. Since cholecystokinin acts on vagal afferent neurones, we asked whether the leptin receptor was also expressed by these neurones. Primers for different forms of the leptin receptor were used in reverse transcriptase-polymerase chain reaction (RT-PCR) of rat and human nodose ganglia. RT-PCR yielded products corresponding to the long (functional) form as well as short forms of the rat leptin receptor. Moreover, RT-PCR revealed the long form of the leptin receptor in a human nodose ganglion. The identities of RT-PCR products were confirmed by sequencing. Primers corresponding to leptin itself did not give RT-PCR products in nodose ganglia. Immunocytochemical studies revealed leptin-receptor immunoreactivity in neuronal cell bodies. Many neurones co-expressed the leptin and cholecystokinin type A receptors, or leptin receptor and cocaine- and amphetamine-related transcript. We conclude that vagal afferent neurones that express the cholecystokinin type A receptor and cocaine- and amphetamine-related transcript, may also express the long form of the leptin receptor providing a neurochemical basis for observations of interactions between cholecystokinin and leptin.
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MESH Headings
- Animals
- Appetite Regulation/physiology
- Calcitonin Gene-Related Peptide/genetics
- Calcitonin Gene-Related Peptide/metabolism
- Carrier Proteins/genetics
- Carrier Proteins/metabolism
- Cholecystokinin/metabolism
- DNA, Complementary/genetics
- Fluorescent Antibody Technique
- Humans
- In Situ Hybridization
- Leptin/metabolism
- Microscopy, Confocal
- Molecular Sequence Data
- Nerve Tissue Proteins/genetics
- Nerve Tissue Proteins/metabolism
- Neurons, Afferent/cytology
- Neurons, Afferent/metabolism
- Nodose Ganglion/cytology
- Nodose Ganglion/metabolism
- RNA, Messenger/metabolism
- Rats
- Rats, Wistar
- Receptor, Cholecystokinin A
- Receptors, Cell Surface
- Receptors, Cholecystokinin/genetics
- Receptors, Cholecystokinin/metabolism
- Receptors, Leptin
- Sequence Homology, Nucleic Acid
- Visceral Afferents/cytology
- Visceral Afferents/metabolism
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Affiliation(s)
- G Burdyga
- Physiological Laboratory, University of Liverpool, Liverpool L69 3BX, UK
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9
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Abstract
Falls in blood glucose induce hunger and initiate feeding. The lateral hypothalamic area (LHA) contains glucose-sensitive neurons (GSNs) and orexin neurons, both of which are stimulated by falling blood glucose and are implicated in hypoglycemia-induced feeding. We combined intracellular electrophysiological recording with fluorescein labeling of GSNs to determine their neuroanatomic and functional relationships with orexin neurons. Orexin A (1 micromol/l) caused a 500% increase (P < 0.01) in spontaneous firing rate and rapid and lasting depolarization that was tetrodotoxin-resistant and thus a direct postsynaptic effect. Orexin A altered the intrinsic neuronal properties of GSNs, consistent with increased excitability. Confocal microscopy showed that GSNs were intimately related to orexin neurons: orexin-immunoreactive axons were frequently entwined around GSN dendrites, establishing close and putatively synaptic contacts. Orexin-cell axons also passed in close proximity to glucose-responsive neurons, which are inhibited by low glucose, but orexin A caused smaller depolarization than on GSNs and only a 200% increase in spontaneous firing rate (P < 0.05 vs. GSN). We conclude that GSNs are specific target neurons for orexin A and suggest that they may mediate, at least in part, the acute appetite-stimulating effect of orexin A. Orexin neurons may regulate GSNs so as to control the onset and termination of hypoglycemia-induced feeding.
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Affiliation(s)
- X H Liu
- Diabetes and Endocrinology Research Group, Department of Medicine University of Liverpool, Liverpool, UK
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11
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Abstract
The effects of two levels of nutrition (400 g and 1000 g air dry matter milk substitute powder per day) and three ages of weaning (five, nine and 13 weeks) on cellular immune responses were determined in 32 calves. The lower level of nutrition was found to increase skin sensitivity responses to keyhole limpet haemocyanin (KLH) and decrease lymphocyte blastogenesis test (LBT) responses to ConA and pokewood mitogen (P < 0.05). Weaning at five weeks old resulted in increased KLH skin responses at nine weeks old compared with unweaned calves and decreased LBT responses to ConA and phyto-haemagglutinin at 10 weeks old compared with calves weaned at nine weeks old (P < 0.05). Weaning at five weeks old also increased peripheral blood concentrations of BoCD2+ and BoCD8+ lymphocytes (P < 0.05). The results show that the choice of husbandry conditions alters cellular immune responses in young calves and suggest that early weaning effects are essentially nutritional.
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Affiliation(s)
- J M Pollock
- Department of Animal Husbandry, University of Liverpool
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Chatterjee S, May PL, Forster G, Spiller D, Jeffreys RV. Prediction of recurrence in pituitary tumours: a flow cytometric study using in vivo bromodeoxyuridine. Br J Neurosurg 1993; 7:165-9. [PMID: 8494618 DOI: 10.3109/02688699309103473] [Citation(s) in RCA: 6] [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: 01/31/2023]
Abstract
Although most pituitary tumours are regarded as benign, there is a significant risk of local recurrence and a few are frankly malignant. The prediction of clinically aggressive behaviour by histopathological means is inadequate and the selection of patients for postoperative radiotherapy has often been empirical. The flow cytometric analysis of the DNA content of certain intracranial tumours has suggested a correlation between a high proliferative index and a tendency to recur. The in vivo administration of bromodeoxyuridine (BUdR) yields a reliable and accurate S-phase labelling index and evaluation by flow cytometry allows a much greater and therefore more representative number of cells to be examined. We report our results for the flow cytometric evaluation of the S-phase fraction in a group of 11 human pituitary tumours following the preoperative administration of BUdR and discuss the correlation between high values of S-phase fraction and clinically aggressive behaviour. Initial results suggest a correlation between radiological evidence of tumour invasion and an S-phase greater than 2%.
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Affiliation(s)
- S Chatterjee
- Walton Centre for Neurology and Neurosurgery, Walton Hospital, Liverpool, UK
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13
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Cooke LD, Cooke TG, Bootz F, Forster G, Helliwell TR, Spiller D, Stell PM. Ploidy as a prognostic indicator in end stage squamous cell carcinoma of the head and neck region treated with cisplatinum. Br J Cancer 1990; 61:759-62. [PMID: 2337512 PMCID: PMC1971589 DOI: 10.1038/bjc.1990.169] [Citation(s) in RCA: 22] [Impact Index Per Article: 0.6] [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] [Indexed: 12/31/2022] Open
Abstract
We measured tumour cellular DNA in 102 patients entered into two phase III trials of chemotherapy for end stage squamous carcinoma of the head and neck. The median survival of untreated patients with aneuploid tumours was 55 days compared with 224 days for patients treated with cisplatinum. This difference was highly significant. In contrast the median survival of untreated patients with diploid tumours was 74 days compared with 118 days for treated patients. Although this difference is statistically significant, the increased survival of 6 weeks is of no clinical benefit compared with the prolongation of survival of 6 months in patients with aneuploid tumours. Multivariate analysis showed that the significant predictors of survival were Karnofsky status, response to chemotherapy and ploidy.
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Affiliation(s)
- L D Cooke
- Department of Otorhinolaryngology, University of Liverpool, UK
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14
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Abstract
When fasting fifth-instar larvae of Rhodnius prolixus Stål were poisoned with a lethal dose of DDT, the rate of oxygen consumption increased from the onset of hyperactivity, reached a marked peak shortly after knockdown, and then declined. For some days after the peak the oxygen consumption was markedly in excess of that prior to poisoning with DDT. Eventually, the oxygen consumption fell below the pre-teatment value and continued at this low level for some days, although the insect was then undoubtedly dead and in one case had been bisected. There was no marked discontinuity in the declining phase of oxygen consumption and therefore there is no indication of when death occurred. It is concluded that the time of death in DDT-poisoned larvae of Rhodnius cannot be determined by measurements of oxygen consumption.The total oxygen consumed from poisoning until death was always less than that consumed in the normal use of all metabolic reserves by the fasting insect, and these experiments do not support the hypothesis that death in DDT poisoning is due to total exhaustion of metabolic reserves. However, it is pointed out that, in Rhodnius, some of the metabolic reserves are contained in the undigested residue of the blood-meal and in the massive endocuticle and that there is no reason to think that either digestion of the remaining blood-meal or resorption of the endocuticle could be speeded up during DDT poisoning. Hence there is a strong possibility that, in DDT-killed Rhodnius, death is brought about by exhaustion of the available reserves.The peak rate of oxygen consumption during poisoning was greatest in very recently fed larvae and decreased as the interval between moulting and DDT-treatment was increased. This suggests that knockdown occurs when the fuel demands of the DDT-induced activity exceed the rate at which the fuel can be mobilised from the metabolic reserves.
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Abstract
Addition of N, N-dibutyl-p-chlorobenzene sulphonamide (Antiresistant/DDT) in amounts equal to one fifth the dose of DDT increased the toxicity of DDT to the DDT-resistant portion of a housefly population. Full susceptibility was not regained. There was no increase in toxicity to the DDT-susceptible portion.
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