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Sanford TC, Tweten RK, Abrahamsen HL. Bacterial cholesterol-dependent cytolysins and their interaction with the human immune response. Curr Opin Infect Dis 2024; 37:164-169. [PMID: 38527455 PMCID: PMC11042984 DOI: 10.1097/qco.0000000000001010] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/27/2024]
Abstract
PURPOSE OF REVIEW Many cholesterol-dependent cytolysin (CDC)-producing pathogens pose a significant threat to human health. Herein, we review the pore-dependent and -independent properties CDCs possess to assist pathogens in evading the host immune response. RECENT FINDINGS Within the last 5 years, exciting new research suggests CDCs can act to inhibit important immune functions, disrupt critical cell signaling pathways, and have tissue-specific effects. Additionally, recent studies have identified a key region of CDCs that generates robust immunity, providing resources for the development of CDC-based vaccines. SUMMARY This review provides new information on how CDCs alter host immune responses to aid bacteria in pathogenesis. These studies can assist in the design of more efficient vaccines and therapeutics against CDCs that will enhance the immune response to CDC-producing pathogens while mitigating the dampening effects CDCs have on the host immune response.
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Affiliation(s)
- Tristan C. Sanford
- University of Oklahoma Health Sciences Center, Department of Microbiology and Immunology, Oklahoma City, OK 73104
| | - Rodney K. Tweten
- University of Oklahoma Health Sciences Center, Department of Microbiology and Immunology, Oklahoma City, OK 73104
| | - Hunter L. Abrahamsen
- University of Oklahoma Health Sciences Center, Department of Microbiology and Immunology, Oklahoma City, OK 73104
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2
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Dorso L, Chartier C, Popoff MR, Tesson C, Despres J, Uzal FA. Postpartum clostridial gangrenous metritis in 12 dairy goats in France. J Vet Diagn Invest 2023; 35:266-271. [PMID: 36912442 DOI: 10.1177/10406387231161508] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/14/2023] Open
Abstract
Clostridial infections in goats have been associated frequently with enteric diseases or gas gangrene but very rarely with the reproductive system. We describe here 12 cases of fatal postpartum gangrenous metritis in does associated with infection by several clostridial species. Clinically, these cases were characterized by rapid onset of hyperthermia followed by death after kidding. On postmortem examination, the uteri appeared to be necrotic and were hemorrhagic and edematous. Microscopically, the uteri had diffuse coagulative necrosis, edema, hemorrhage, and fibrinous thrombi with intralesional gram-positive rods. Clostridium perfringens was isolated from 7 of 9 uterine samples cultured, and C. perfringens, C. septicum, C. novyi, or C. chauvoei were demonstrated by immunohistochemistry (IHC) in the 5 cases examined. IHC for Paeniclostridium sordellii was negative in all 5 cases. PCR performed on 3 of the C. perfringens isolates was positive for alpha toxin and perfringolysin, identifying these isolates as type A. Clostridial infection should be considered in cases of postpartum gangrenous metritis of does.
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Affiliation(s)
- Laëtitia Dorso
- Oniris, INRAE (National Research Institute for Agriculture, Food and the Environment), BIOEPAR (Biology, Epidemiology and Risk Analysis in Animal Health), Nantes, France.,Oniris, CHUV (University Veterinary Hospital), Nantes, France
| | - Christophe Chartier
- Oniris, INRAE (National Research Institute for Agriculture, Food and the Environment), BIOEPAR (Biology, Epidemiology and Risk Analysis in Animal Health), Nantes, France
| | | | | | | | - Francisco A Uzal
- California Animal Health and Food Safety Laboratory System, San Bernardino Laboratory, School of Veterinary Medicine, University of California-Davis, Davis, CA, USA
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Prasad K. Current Status of Primary, Secondary, and Tertiary Prevention of Coronary Artery Disease. Int J Angiol 2021; 30:177-186. [PMID: 34776817 PMCID: PMC8580611 DOI: 10.1055/s-0041-1731273] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022] Open
Abstract
Fifty percent of all death from cardiovascular diseases is due to coronary artery disease (CAD). This is avoidable if early identification is made. Preventive health care has a major role in the fight against CAD. Atherosclerosis and atherosclerotic plaque rupture are involved in the development of CAD. Modifiable risk factors for CAD are dyslipidemia, diabetes, hypertension, cigarette smoking, obesity, chronic renal disease, chronic infection, high C-reactive protein, and hyperhomocysteinemia. CAD can be prevented by modification of risk factors. This paper defines the primary, secondary, and tertiary prevention of CAD. It discusses the mechanism of risk factor-induced atherosclerosis. This paper describes the CAD risk score and its use in the selection of individuals for primary prevention of CAD. Guidelines for primary, secondary, and tertiary prevention of CAD have been described. Modification of risk factors and use of guidelines for prevention of CAD would prevent, regress, and slow down the progression of CAD, improve the quality of life of patient, and reduce the health care cost.
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Affiliation(s)
- Kailash Prasad
- Department of Physiology (APP), College of Medicine, University of Saskatchewan, Saskatoon, Saskatchewan, Canada
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4
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Chaiyabutr N, Chanhome L, Vasaruchapong T, Laoungbua P, Khow O, Rungsipipat A, Sitprija V. The pathophysiological effects of Russell's viper ( Daboia siamensis) venom and its fractions in the isolated perfused rabbit kidney model: A potential role for platelet activating factor. Toxicon X 2020; 7:100046. [PMID: 32875291 PMCID: PMC7452022 DOI: 10.1016/j.toxcx.2020.100046] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2020] [Revised: 05/21/2020] [Accepted: 06/04/2020] [Indexed: 12/20/2022] Open
Abstract
The pathophysiological effects of Russell's viper venom (RVV) and its fractions, including phospholipase A2 (RvPLA2), metalloprotease (RvMP), L-amino acid oxidase (RvLAAO), and phosphodiesterase (RvPDE) on renal functions were investigated using the isolated perfused rabbit kidney (IPK) model. Moreover, whether their effects on renal alterations were promoted by platelet activating factor (PAF) was tested using the PAF receptor antagonist, WEB 2086. There was a marked reduction in the perfusion pressure (PP) and renal vascular resistance (RVR) 10 min after RVV administration (1.0 mg/100 ml of perfusate), thereafter both PP and RVR gradually increased and approached the control level within 90 min. These effects were abolished by pretreatment with WEB2086 (2 μg/μl). Administration with RvPLA2 (280 μg/ml), RvMP (280 μg/ml), or RvLAAO (135 μg/ml) alone increased both the PP and RVR, whereas RvPDE (100 μg/ml) reduced both the PP and RVR. Pretreatment with WEB 2086 completely abolished the effects induced by RvMP, but not the other fractions. The RVV also caused a marked decrease in the glomerular filtration rate (GFR), urinary flow rate (UF), and osmolar clearance (Cosm), and these effects were not inhibited by pretreatment with WEB2086. Each RVV fraction also increased, to varying extents, the GFR, UF, and Cosm, and these effects induced by RvPLA2 or RvMP, but not the other fractions, were completely blocked by WEB 2086. Changes in percent filtered Na+ and K+ excreted in the IPK by RVV, RvPDE, and RvMP were abolished by pretreatment with WEB 2086. Histological evaluation profiled mainly tubulonephrosis in the treated kidney. These results reveal that the alterations in renal functions induced by RVV and its fractions are due to the synergistic action of the different components of snake venom, instead of the action of a single component. The effects of RVV and its fractions in rabbit IPK are mediated at least in part by PAF.
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Affiliation(s)
- Narongsak Chaiyabutr
- Queen Saovabha Memorial Institute, The Thai Red Cross Society, Bangkok, 10330, Thailand
| | - Lawan Chanhome
- Queen Saovabha Memorial Institute, The Thai Red Cross Society, Bangkok, 10330, Thailand
| | - Taksa Vasaruchapong
- Queen Saovabha Memorial Institute, The Thai Red Cross Society, Bangkok, 10330, Thailand
| | - Panithi Laoungbua
- Queen Saovabha Memorial Institute, The Thai Red Cross Society, Bangkok, 10330, Thailand
| | - Orawan Khow
- Queen Saovabha Memorial Institute, The Thai Red Cross Society, Bangkok, 10330, Thailand
| | - Anudep Rungsipipat
- Department of Veterinary Pathology, Faculty of Veterinary Science, Chulalongkorn University, Bangkok, 10330, Thailand
| | - Visith Sitprija
- Queen Saovabha Memorial Institute, The Thai Red Cross Society, Bangkok, 10330, Thailand
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5
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Nagahama M, Takehara M, Rood JI. Histotoxic Clostridial Infections. Microbiol Spectr 2019; 7:10.1128/microbiolspec.gpp3-0024-2018. [PMID: 31350831 PMCID: PMC10957196 DOI: 10.1128/microbiolspec.gpp3-0024-2018] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2018] [Indexed: 01/01/2023] Open
Abstract
The pathogenesis of clostridial myonecrosis or gas gangrene involves an interruption to the blood supply to the infected tissues, often via a traumatic wound, anaerobic growth of the infecting clostridial cells, the production of extracellular toxins, and toxin-mediated cell and tissue damage. This review focuses on host-pathogen interactions in Clostridium perfringens-mediated and Clostridium septicum-mediated myonecrosis. The major toxins involved are C. perfringens α-toxin, which has phospholipase C and sphingomyelinase activity, and C. septicum α-toxin, a β-pore-forming toxin that belongs to the aerolysin family. Although these toxins are cytotoxic, their effects on host cells are quite complex, with a range of intracellular cell signaling pathways induced by their action on host cell membranes.
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Affiliation(s)
- Masahiro Nagahama
- Department of Microbiology, Faculty of Pharmaceutical Sciences, Tokushima Bunri University, Yamashiro-cho, Tokushima 770-8514, Japan
| | - Masaya Takehara
- Department of Microbiology, Faculty of Pharmaceutical Sciences, Tokushima Bunri University, Yamashiro-cho, Tokushima 770-8514, Japan
| | - Julian I Rood
- Infection and Immunity Program, Monash Biomedicine Discovery Institute and Department of Microbiology, Monash University, Clayton, Victoria 3800, Australia
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6
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Goossens E, Valgaeren BR, Pardon B, Haesebrouck F, Ducatelle R, Deprez PR, Van Immerseel F. Rethinking the role of alpha toxin in Clostridium perfringens-associated enteric diseases: a review on bovine necro-haemorrhagic enteritis. Vet Res 2017; 48:9. [PMID: 28209206 PMCID: PMC5314468 DOI: 10.1186/s13567-017-0413-x] [Citation(s) in RCA: 35] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2016] [Accepted: 01/12/2017] [Indexed: 11/23/2022] Open
Abstract
Bovine necro-haemorrhagic enteritis is an economically important disease caused by Clostridium perfringens type A strains. The disease mainly affects calves under intensive rearing conditions and is characterized by sudden death associated with small intestinal haemorrhage, necrosis and mucosal neutrophil infiltration. The common assumption that, when causing intestinal disease, C. perfringens relies upon specific, plasmid-encoded toxins, was recently challenged by the finding that alpha toxin, which is produced by all C. perfringens strains, is essential for necro-haemorrhagic enteritis. In addition to alpha toxin, other C. perfringens toxins and/or enzymes might contribute to the pathogenesis of necro-haemorrhagic enteritis. These additional virulence factors might contribute to breakdown of the protective mucus layer during initial stage of pathogenesis, after which alpha toxin, either or not in synergy with other toxins such as perfringolysin O, can act on the mucosal tissue. Furthermore, alpha toxin alone does not cause intestinal necrosis, indicating that other virulence factors might be needed to cause the extensive tissue necrosis observed in necro-haemorrhagic enteritis. This review summarizes recent research that has increased our understanding of the pathogenesis of bovine necro-haemorrhagic enteritis and provides information that is indispensable for the development of novel control strategies, including vaccines.
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Affiliation(s)
- Evy Goossens
- Department of Pathology, Bacteriology and Avian Diseases, Faculty of Veterinary Medicine, Ghent University, Salisburylaan 133, B-9820, Merelbeke, Belgium
| | - Bonnie R Valgaeren
- Department of Large Animal Internal Medicine, Faculty of Veterinary Medicine, Ghent University, Salisburylaan 133, B-9820, Merelbeke, Belgium
| | - Bart Pardon
- Department of Large Animal Internal Medicine, Faculty of Veterinary Medicine, Ghent University, Salisburylaan 133, B-9820, Merelbeke, Belgium
| | - Freddy Haesebrouck
- Department of Pathology, Bacteriology and Avian Diseases, Faculty of Veterinary Medicine, Ghent University, Salisburylaan 133, B-9820, Merelbeke, Belgium
| | - Richard Ducatelle
- Department of Pathology, Bacteriology and Avian Diseases, Faculty of Veterinary Medicine, Ghent University, Salisburylaan 133, B-9820, Merelbeke, Belgium
| | - Piet R Deprez
- Department of Large Animal Internal Medicine, Faculty of Veterinary Medicine, Ghent University, Salisburylaan 133, B-9820, Merelbeke, Belgium
| | - Filip Van Immerseel
- Department of Pathology, Bacteriology and Avian Diseases, Faculty of Veterinary Medicine, Ghent University, Salisburylaan 133, B-9820, Merelbeke, Belgium.
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7
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Stevens DL, Aldape MJ, Bryant AE. Necrotizing Fasciitis, Gas Gangrene, Myositis and Myonecrosis. Infect Dis (Lond) 2017. [DOI: 10.1016/b978-0-7020-6285-8.00011-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/21/2022] Open
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8
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Perfringolysin O: The Underrated Clostridium perfringens Toxin? Toxins (Basel) 2015; 7:1702-21. [PMID: 26008232 PMCID: PMC4448169 DOI: 10.3390/toxins7051702] [Citation(s) in RCA: 41] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2015] [Accepted: 05/08/2015] [Indexed: 12/21/2022] Open
Abstract
The anaerobic bacterium Clostridium perfringens expresses multiple toxins that promote disease development in both humans and animals. One such toxin is perfringolysin O (PFO, classically referred to as θ toxin), a pore-forming cholesterol-dependent cytolysin (CDC). PFO is secreted as a water-soluble monomer that recognizes and binds membranes via cholesterol. Membrane-bound monomers undergo structural changes that culminate in the formation of an oligomerized prepore complex on the membrane surface. The prepore then undergoes conversion into the bilayer-spanning pore measuring approximately 250–300 Å in diameter. PFO is expressed in nearly all identified C. perfringens strains and harbors interesting traits that suggest a potential undefined role for PFO in disease development. Research has demonstrated a role for PFO in gas gangrene progression and bovine necrohemorrhagic enteritis, but there is limited data available to determine if PFO also functions in additional disease presentations caused by C. perfringens. This review summarizes the known structural and functional characteristics of PFO, while highlighting recent insights into the potential contributions of PFO to disease pathogenesis.
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9
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Recessive mutations in DGKE cause atypical hemolytic-uremic syndrome. Nat Genet 2013; 45:531-6. [PMID: 23542698 PMCID: PMC3719402 DOI: 10.1038/ng.2590] [Citation(s) in RCA: 327] [Impact Index Per Article: 29.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2012] [Accepted: 03/01/2013] [Indexed: 12/14/2022]
Abstract
Pathologic thrombosis is a major cause of mortality. Hemolytic-uremic syndrome (HUS) features episodes of small-vessel thrombosis resulting in microangiopathic hemolytic anemia, thrombocytopenia and renal failure. Atypical HUS (aHUS) can result from genetic or autoimmune factors that lead to pathologic complement cascade activation. Using exome sequencing, we identified recessive mutations in DGKE (encoding diacylglycerol kinase ɛ) that co-segregated with aHUS in nine unrelated kindreds, defining a distinctive Mendelian disease. Affected individuals present with aHUS before age 1 year, have persistent hypertension, hematuria and proteinuria (sometimes in the nephrotic range), and develop chronic kidney disease with age. DGKE is found in endothelium, platelets and podocytes. Arachidonic acid-containing diacylglycerols (DAG) activate protein kinase C (PKC), which promotes thrombosis, and DGKE normally inactivates DAG signaling. We infer that loss of DGKE function results in a prothrombotic state. These findings identify a new mechanism of pathologic thrombosis and kidney failure and have immediate implications for treating individuals with aHUS.
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10
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Oxygen free radicals as a mechanism of hypercholesterolemic atherosclerosis: Effects of probucol. Int J Angiol 2011. [DOI: 10.1007/bf02014924] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023] Open
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11
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Prasad K, Gupta J, Kalra J. Effects of platelet-activating factor on cardiovascular function, oxygen free radical status, and blood chemistry. Int J Angiol 2011. [DOI: 10.1007/bf02014905] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022] Open
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12
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Stevens DL, Aldape MJ, Bryant AE. Necrotizing fasciitis, gas gangrene, myositis and myonecrosis. Infect Dis (Lond) 2010. [DOI: 10.1016/b978-0-323-04579-7.00010-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/17/2022] Open
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13
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Abstract
This review is focused on the effects of histamine and platelet-activating factor (PAF) in allergic rhinitis and the plausible implications for therapy. Rhinitis is defined as a heterogeneous disorder resulting from an IgE-mediated reaction associated with nasal inflammation of variable intensity. Two phases of response are triggered by an IgE/allergen cross-linking event: the first is the release of preformed mediators such as histamine or interleukins from mast cells and basophils; the second begins when cells start producing lipid-derived mediators. One of these mediators is PAF. Apart from leukotrienes, PAF is perhaps the most potent inflammatory mediator in allergic rhinitis for inducing vascular leakage, a response that may contribute to the appearance of rhinorrhea and nasal congestion.
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Affiliation(s)
- V Alfaro
- Department of Physiology, University of Barcelona, Avda. Diagonal 645, 08028 Barcelona, Spain.
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Facó PEG, Havt A, Barbosa PSF, Nobre ACL, Bezerra GP, Menezes DB, Fonteles MC, Lopes-Ferreira M, Monteiro HSA. Effects of Thalassophryne nattereri fish venom in isolated perfused rat kidney. Toxicon 2003; 42:509-14. [PMID: 14529732 DOI: 10.1016/s0041-0101(03)00229-0] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
Thalassophryne nattereri, popularly known as Niquim, is a venomous fish responsible for many accidents in fishermen in the Northeast of Brazil. The effects of T. nattereri venom on renal physiology has not been tested. Isolated kidneys from Wistar rats of 240-280 g weight were perfused with Krebs-Henseleit solution containing 6g% of previously dialyzed bovine serum albumin. The effects of Niquim venom were studied on the perfusion pressure (PP), renal vascular resistance (RVR), urinary flow (UF), glomerular filtration rate (GFR), percent of sodium tubular transport (%TNa(+)), percent of potassium tubular transport (%TK(+)) and percent of chloride tubular transport (%TCl(-)). The venom of T. nattereri (0.3, 1.0, and 3.0 microg/ml) was always added to the system 30 minutes after the beginning of each experiment (n=6). All experiments were preceded by 30 minutes internal control period and an external control group, where kidneys were perfused with only Krebs-Henseleit solution. All three doses tested promoted increases in PP and RVR. The first two doses also increased GFR and UF. The higher dose promoted decreases in GFR, UF, %TNa(+), %TK(+), %TCl(-). In the treated groups we observed hyalin casts inside all tubules and proteinaceous material in the urinary space. We conclude that the effects resulted from niquim venom agents that promoted a direct effect in kidney cells causing the release of vasoactive factors.
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Affiliation(s)
- P E G Facó
- Department of Pathology and Forensic Medicine, Rua Monsenhor Furtado, S/N, 60441-750 Fortaleza, CE, Brazil
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15
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Auger S, Vallerand D, Haddad PS. Cold preservation-warm reperfusion perturbs cytosolic calcium ion homeostasis in rat liver sinusoidal endothelial cells. Liver Transpl 2003; 9:150-9. [PMID: 12548509 DOI: 10.1053/jlts.2003.50025] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Increases in intracellular calcium ion (Ca(2+)) levels of sinusoidal endothelial cell (SEC) may have a crucial role in mediating the expression of adhesion molecules and thus contribute to the microcirculatory disturbances observed in primary graft dysfunction. The effect of changes in the composition and/or temperature of the reperfusion solution on cytosolic Ca(2+) was studied in isolated rat SECs. Cells were preserved in cold University of Wisconsin (UW) solution for 0, 12, or 24 hours and loaded with Fura-2AM dye (Cedarlane, Eugene, OR) at 20 degrees C in N-2-hydroxyethylpiperazine-propanesulfonic acid (HEPES)-buffered physiological solution (HEPES 20 degrees C) or UW solution (UW 20 degrees C). SEC Ca(2+) levels were measured by cytofluorimetry. Basal steady-state Ca(2+) levels were much lower when SECs were loaded in UW 20 degrees C (37 +/- 2 nmol/L) than in HEPES 20 degrees C (114 +/- 32 nmol/L). In unstored controls (0 hour), going from UW 20 degrees C to HEPES 37 degrees C induced a large transient increase (185 +/- 31 nmol/L) in SEC Ca(2+) levels, which was greatly inhibited (43 +/- 13 nmol/L) in Ca(2+)-free HEPES 37 degrees C. A similar large transient increase was observed going from UW 20 degrees C to HEPES 20 degrees C (163 +/- 22 nmol/L). Changing temperature only (20 degrees C to 37 degrees C) in UW or HEPES solution had a much smaller effect on SEC Ca(2+) levels (14 +/- 2 and 60 +/- 18 nmol/L, respectively). These changes were similar in cold-preserved cells. In unstored controls, solution changes greatly attenuated the intensity of subsequent Ca(2+) responses to the purinergic agonist adenosine triphosphate (ATP). Cold preservation (CP) greatly attenuated both the frequency of appearance and intensity of ATP-induced Ca(2+) responses. Hence, changing reperfusion solution composition has a greater impact on SEC steady-state Ca(2+) levels than changing temperature. Cold preservation does not significantly affect changes in SEC steady-state Ca(2+) levels, but greatly impairs the capacity of SECs to subsequently respond to Ca(2+)-mobilizing agonists.
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Affiliation(s)
- Stéphanie Auger
- Department of Pharmacology, Université de Montréal, Quebec, Canada
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16
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Ren DC, Du GH, Zhang JT. Protective effect of ginkgo biloba extract on endothelial cell against damage induced by oxidative stress. J Cardiovasc Pharmacol 2002; 40:809-14. [PMID: 12451313 DOI: 10.1097/00005344-200212000-00001] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
The viability of bovine aortic endothelial cells (BAECs) treated with 0.1 m H O was decreased by 39.8%, and 100 mg/l EGb761 increased the viability by 20.6%. Exposure BAECs to H O for 6 min resulted in a significant elevation in the intracellular free Ca. Pretreatment of BAECs with 10 mg/l and 100 mg/l EGb761 for 10 min showed a decrease in the intracellular free Ca, 4.5% and 20.6%, respectively. The apoptotic rate of BAECs measured by propidium iodide (PI) staining was (38.1 +/- 2%) after 18 h of treatment with H O. Pretreatment of BAECs with 100 mg/l EGb761 for 1 h reduced the apoptotic rate to 27 +/- 1%. In addition, there were about 5-7% of cells stained positive measured by TUNEL assay. When BAECs were exposed to 0.1 m H O for 18 h, the number of TUNEL-positive cells increased to 37-44%. When 10 mg/l EGb761 and 100 mg/l EGb761 were used, the TUNEL-positive cells decreased to 26.5 +/- 3.1% and 17.5 +/- 1.7%, respectively. Furthermore, EGb761 also inhibited caspase-3 activity induced by H O. It is concluded that EGb761 has protective effect on bovine vascular endothelial cells against damage induced by H O. Further studies are needed to clarify the mechanisms of action of EGb761.
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Affiliation(s)
- De Cheng Ren
- Instiute of Materia Medica, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, China
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17
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Stevens DL, Bryant AE. The role of clostridial toxins in the pathogenesis of gas gangrene. Clin Infect Dis 2002; 35:S93-S100. [PMID: 12173116 DOI: 10.1086/341928] [Citation(s) in RCA: 91] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022] Open
Abstract
Clostridium perfringens gas gangrene is, without a doubt, the most fulminant necrotizing infection that affects humans. In victims of traumatic injury, the infection can become well established in as little as 6-8 h, and the destruction of adjacent healthy muscle can progress several inches per hour despite appropriate antibiotic coverage. Shock and organ failure are present in 50% of patients and, among these, 40% die. Despite modern medical advances and intensive-care regimens, radical amputation remains the single best life-saving treatment. Over the past century, much has been learned about the pathogenesis of this disease, and novel therapies are on the horizon for patients with this devastating infection.
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Affiliation(s)
- Dennis L Stevens
- Veterans Affairs Medical Center, Boise, ID, USA; and University of Washington School of Medicine, Seattle, WA, USA.
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18
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Abstract
Hyperglycaemia appears to be a critical factor in the aetiology of diabetic retinopathy and initiates downstream events including: basement membrane thickening, pericyte drop out and retinal capillary non-perfusion. More recently, focus has been directed to the molecular basis of the disease process in diabetic retinopathy. Of particular importance in the development and progression of diabetic retinopathy is the role of growth factors (eg vascular endothelial growth factor, placenta growth factor and pigment epithelium-derived factor) together with specific receptors and obligate components of the signal transduction pathway needed to support them. Despite these advances there are still a number of important questions that remain to be answered before we can confidently target pathological signals. How does hyperglycaemia regulate retinal vessels? Which growth factors are most important and at what stage of retinopathy do they operate? What is the preferred point in the growth factor signalling cascade for therapeutic intervention? Answers to these questions will provide the basis for new therapeutic interventions in a debilitating ocular condition.
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Affiliation(s)
- J Cai
- Department of Optometry and Vision Sciences, Cardiff University, UK
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19
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Marathe GK, Zimmerman GA, Prescott SM, McIntyre TM. Activation of vascular cells by PAF-like lipids in oxidized LDL. Vascul Pharmacol 2002; 38:193-200. [PMID: 12449015 DOI: 10.1016/s1537-1891(02)00169-6] [Citation(s) in RCA: 55] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
The components of inflammation, including macrophages, cytokines and lipid inflammatory mediators, have a role in atherosclerosis. A key lipid mediator in regulated, physiologic inflammation is platelet-activating factor (PAF). PAF activates cells, including monocytes, through a single molecularly characterized receptor, the PAF receptor (PAFR), at exceedingly low concentrations. The PAFR recognizes the short residue, an acetate residue, at the 2-position of the phospholipid, and this sharp specificity precludes receptor activation by other related phosphatidylcholines. Oxidation of low-density lipoproteins (LDLs) is an early and causal step in atherosclerosis that generates inflammatory compounds leading to foam cell formation. One class of oxidatively generated inflammatory compounds are phospholipids that structurally mimic PAF, the PAF-like lipids. Oxidation of LDLs fragments and derivatizes the fatty acid residues at the 2-position of the phosphatidylcholines that comprise the shell of LDLs, an event that allows certain oxidized phospholipids to interact with and activate the PAFR. We know that these products activate polymorphonuclear leukocytes, but because the function of the PAFR differs among cells, we do not know if monocytes or platelets themselves respond to PAF-like lipids. Here, we show that PAF-like lipids from oxidized LDLs are potent and serve as specific agonists for all cells that express the PAFR.
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Affiliation(s)
- Gopal K Marathe
- Department of Internal Medicine, Human Molecular Biology and Genetics Program, University of Utah, Salt Lake City, UT 84112, USA
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Bernatchez PN, Allen BG, Gélinas DS, Guillemette G, Sirois MG. Regulation of VEGF-induced endothelial cell PAF synthesis: role of p42/44 MAPK, p38 MAPK and PI3K pathways. Br J Pharmacol 2001; 134:1253-62. [PMID: 11704645 PMCID: PMC1573057 DOI: 10.1038/sj.bjp.0704367] [Citation(s) in RCA: 39] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022] Open
Abstract
1. Vascular endothelial growth factor (VEGF) is a potent angiogenic and inflammatory mediator. We have recently shown that this latter effect requires the activation of Flk-1 receptor and subsequent endothelial cell (EC) PAF synthesis. However, the intracellular events that regulate EC PAF synthesis upon Flk-1 stimulation by VEGF remain to be elucidated. 2. Using specific inhibitors and Western blot analysis, we herein report that in bovine aortic endothelial cells (BAEC), VEGF induces the synthesis of PAF through the cascade activation of Flk-1 receptor, phospholipase Cgamma (PLCgamma), protein kinase C (PKC) and p42/44 mitogen-activated protein kinases (MAPK). 3. Moreover, we demonstrate that VEGF-mediated PAF synthesis requires the activation of p38 MAPK, likely by directing the conversion of lyso-PAF to PAF. 4. Interestingly, we observed that VEGF also promoted the activation of the phosphatidyl inositol-3-phosphate kinase (PI3K) pathway, and that its blockade potentiated PAF synthesis following a VEGF treatment. Consequently, it appears that the PI3K pathway acts as a negative regulator of EC PAF synthesis. 5. Taken together, these results allow a better understanding of the intracellular events activated upon EC stimulation by VEGF, and shed a new light on the mechanisms by which VEGF induces PAF synthesis.
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Affiliation(s)
- Pascal N Bernatchez
- Research Center, Montreal Heart Institute, Department of Pharmacology, University of Montreal, Montreal (Qc), Canada
| | - Bruce G Allen
- Department of Biochemistry, University of Montreal, Montreal (Qc), Canada
| | - David S Gélinas
- Research Center, Montreal Heart Institute, Department of Pharmacology, University of Montreal, Montreal (Qc), Canada
| | - Gaétan Guillemette
- Department of Pharmacology, University of Sherbrooke, Sherbrooke (Qc), Canada
| | - Martin G Sirois
- Research Center, Montreal Heart Institute, Department of Pharmacology, University of Montreal, Montreal (Qc), Canada
- Author for correspondence:
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21
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Bernatchez PN, Winstead MV, Dennis EA, Sirois MG. VEGF stimulation of endothelial cell PAF synthesis is mediated by group V 14 kDa secretory phospholipase A2. Br J Pharmacol 2001; 134:197-205. [PMID: 11522612 PMCID: PMC1572915 DOI: 10.1038/sj.bjp.0704215] [Citation(s) in RCA: 41] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022] Open
Abstract
1. Vascular endothelial growth factor (VEGF) is a potent inducer of inflammation, and we have shown that this latter effect is mediated through endothelial cell (EC) PAF synthesis. Since the phospholipid remodelling pathway enzymes (CoA-independent transacylase, CoA-IT; phospholipase A2, PLA2; and lyso-PAF acetyltransferase, lyso-PAF-AT) may participate in PAF synthesis, we assessed their contribution to VEGF-induced PAF synthesis in bovine aortic EC (BAEC) and human umbilical vein EC (HUVEC). 2. VEGF enhanced BAEC and HUVEC PAF synthesis by up to 28 and 4 fold above basal levels respectively. 3. A pretreatment with a CoA-IT and lyso-PAF-AT inhibitor (Sanguinarin; 500 nM) blocked VEGF-induced PAF synthesis by 95%, a specific CoA-IT inhibitor (SKF45905; 10 - 50 microM) was without effect, confirming the crucial role of the PLA2 and lyso-PAF-AT. 4. Treatment with secreted PLA2 (sPLA2) inhibitors which have been shown to inhibit both groups IIA and V sPLA2 (SB203347; 10 microM and LY311727; 100 microM) blocked EC PAF synthesis by up to 90%, whereas selective inhibition of group IIA sPLA2 (LY311727; 1 microM) had no significant effect. 5. RT - PCR and Western blot analyses demonstrated the presence of group V sPLA2 whereas group IIA sPLA2 was undetected in EC. 6. Treatment with cytosolic and calcium-independent PLA2 inhibitors (Arachidonyl trifluoromethyl ketone, Bromoenol lactone, Methyl arachydonyl fluorophosphate, up to 50 microM) did not prevent but rather potentiated the VEGF effect on EC PAF synthesis. 7. These results provide evidence that with VEGF activation of EC cells, the group V sPLA2 provides substrate for EC PAF formation.
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Affiliation(s)
- Pascal N Bernatchez
- Research Center, Montreal Heart Institute, and Department of Pharmacology, University of Montreal, Montreal (Qc), Canada
| | - Michelle V Winstead
- Department of Chemistry and Biochemistry, University of California, San Diego, La Jolla, California, CA, 92093-0601, U.S.A
| | - Edward A Dennis
- Department of Chemistry and Biochemistry, University of California, San Diego, La Jolla, California, CA, 92093-0601, U.S.A
| | - Martin G Sirois
- Research Center, Montreal Heart Institute, and Department of Pharmacology, University of Montreal, Montreal (Qc), Canada
- Author for correspondence:
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Marathe GK, Harrison KA, Roberts LJ, Morrow JD, Murphy RC, Tjoelker LW, Prescott SM, Zimmerman GA, McIntyre TM. Identification of platelet-activating factor as the inflammatory lipid mediator in CCl4-metabolizing rat liver. J Lipid Res 2001. [DOI: 10.1016/s0022-2275(20)31168-8] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022] Open
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Sandhu SK, Bhardwaj SK, Sharma P, Kaur G. Alterations in signal transduction cascade in young and adult rat brain and lymphocytes. Brain Res Bull 2001; 54:513-20. [PMID: 11397541 DOI: 10.1016/s0361-9230(01)00437-3] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
Signal transduction cascade, phosphoinositide metabolism, and protein kinases were studied from discrete areas of rat brain like cerebral hemispheres, cerebellum, brainstem, and diencephalon as well as lymphocytes isolated from three different age groups of rats; young (1 month), young adult (3-4 months), and adult (12 months) rats. The activities of protein kinase A, protein kinase C, phospholipase A(2) and phospholipase C and inositol 1, 4, 5-triphosphate, diacylglycerol, cyclic adenosine monophosphate contents were assayed from different brain areas and lymphocytes from these three age group rats. An upregulatory effect on the signal transduction system was observed from 1 month to 3-4-month age group, whereas, the brain tissue and lymphocytes of adult rats showed lower contents and activities of signal transduction components as compared to young adults. In view of the established 'cross talk' between signal transduction system, the present results suggests that molecular/cellular changes in brain and immune cells signal transduction pathway along with neuronal cell loss may contribute to age-related decline in nervous as well as immune system functions.
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Affiliation(s)
- S K Sandhu
- Department of Biotechnology, Guru Nanak Dev University, Amritsar, India
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24
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Hutcheson IR, Griffith TM. Role of phospholipase A(2) and myoendothelial gap junctions in melittin-induced arterial relaxation. Eur J Pharmacol 2000; 406:239-45. [PMID: 11020487 DOI: 10.1016/s0014-2999(00)00643-9] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Abstract
We have used preconstricted rings of rabbit superior mesenteric artery to investigate the contribution of phospholipase A(2) and gap junctional communication to endothelium-derived hyperpolarizing factor (EDHF)-type relaxations evoked by melittin, a polypeptide toxin known to mobilize arachidonic acid from the cell membrane. Arachidonyl trifluoromethyl ketone (30 microM), an inhibitor of the Ca(2+)-dependent phospholipase A(2), and Gap 27 (300 microM), a connexin-mimetic peptide which attenuates intercellular communication via gap junctions, both abolished the endothelium-dependent component of EDHF-type responses evoked by melittin in the presence of the NO synthase inhibitor N(G)-nitro-L-arginine methyl ester (L-NAME, 300 microM) and the cyclooxygenase inhibitor indomethacin (10 microM). By contrast, the sulfhydryl agent thimerosal (300 nM), which amplifies EDHF activity, potentiated nitric oxide (NO)/prostanoid-independent relaxations induced by melittin. Neither arachidonyl trifluoromethyl ketone nor thimerosal modulated relaxations evoked by the peptide toxin in the absence of L-NAME and indomethacin. We conclude that melittin evokes EDHF-type relaxations through activation of the endothelial Ca(2+)-dependent phospholipase A(2) followed by the transmission of a chemical and/or electrical signal via myoendothelial gap junctions. This mechanism of vasorelaxation may be negatively regulated by NO.
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Affiliation(s)
- I R Hutcheson
- Department of Diagnostic Radiology, Wales Heart Research Institute, University of Wales College of Medicine, Health Park, CF14 4XN, Cardiff, UK
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25
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Abstract
These pieces of evidence can be assimilated into a molecular and cellular model of pathogenesis which is initiated by direct toxin effects upon venous capillary endothelial cell function, leading to expression of pro-inflammatory mediators and adhesion molecules, and initiation of platelet aggregation. Toxin-induced hyperadhesion of leukocytes (see above section) with enhanced respiratory burst activity (due to toxins directly or to toxin-induced IL-8 or PAF synthesis by host cells) and toxin-induced chemotaxis deficits could result in neutrophil-mediated vascular injury. Direct toxin-induced cytopathic effects on EC may also contribute to vascular abnormalities associated with gas gangrene. Over prolonged incubation periods, PLC at sublytic concentrations causes EC to undergo profound shape changes similar to those described following prolonged TNF or interferon gamma exposure. In vivo, conversion of EC to this fibroblastoid morphology could contribute to the localized vascular leakage and massive swelling observed clinically with this infection. Similarly, the direct cytotoxicity of PFO could disrupt endothelial integrity and contribute to progressive edema both locally and systemically. Thus, via the mechanisms outlined above, both PLC and PFO may cause local, regional and systemic vascular dysfunction. For instance, local absorption of exotoxins within the capillary beds could affect the physiological function of the endothelium lining the postcapillary venules, resulting in impairment of phagocyte delivery at the site of infection. Toxin-induced endothelial dysfunction and microvascular injury could also cause loss of albumin, electrolytes, and water into the interstitial space resulting in marked localized edema. These events, combined with intravascular platelet aggregation and leukostasis, would increase venous pressures and favor further loss of fluid and protein in the distal capillary bed. Ultimately, a reduced arteriolar flow would impair oxygen delivery thereby attenuating phagocyte oxidative killing and facilitating anaerobic glycolysis of muscle tissue. The resultant drop in tissue pH, together with reduced oxygen tension, might further decrease the redox potential of viable tissues to a point suitable for growth of this anaerobic bacillus. As infection progresses and additional toxin is absorbed, larger venous channels would become affected, causing regional vascular compromise, increased compartment pressures and rapid anoxic necrosis of large muscle groups. When toxins reach arterial circulation, systemic shock and multiorgan failure rapidly ensue, and death is common.
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Affiliation(s)
- D L Stevens
- Veterans Affairs Medical Center, Infectious Diseases Section, Boise, ID 83702, USA.
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26
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Sharma P, Kumar Bhardwaj S, Kaur Sandhu S, Kaur G. Opioid regulation of gonadotropin release: role of signal transduction cascade. Brain Res Bull 2000; 52:135-42. [PMID: 10808084 DOI: 10.1016/s0361-9230(00)00245-8] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
The present investigation elucidates the opioidergic modulation of gonadotropin releasing hormone release mechanism by signal transduction cascade in discrete brain regions from estrogen-progesterone primed ovariectomized rats. The effects of mu-opioid agonist morphine and its antagonist naloxone followed by morphine were studied (in two different groups of rats) on protein kinase A, adenosine 3',5' cyclic monophosphate, protein kinase C and calcium/calmodulin protein kinase-II as well as phospholipase C, phospholipase A(2), diacylglycerol and inositol 1,4, 5-triphosphate. Significant decline in phosphoinositide metabolism was observed after morphine treatment as depicted by decrease in phospholipase C and phospholipase A2 activities as well as inositol 1,4,5-triphosphate and diacylglycerol contents from discrete brain regions. Protein kinase A activity showed translocation from membrane bound to cytosolic form along with a decrease in its activator adenosine 3',5'-cyclic monophosphate levels in morphine-treated group. Calcium/calmodulin dependent protein kinase II activity also declined, whereas, protein kinase C activity increased in the cytosolic fraction after 45 min of morphine administration. Naloxone was seen to counteract the changes induced by morphine in most of the brain regions studied. Morphine also suppressed luteinizing hormone levels, whereas, follicle stimulating hormone level did not change. The present investigation provides evidence for opioidergic mediated suppression of gonadotropin release through the downregulation of signal transduction cascade.
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Affiliation(s)
- P Sharma
- Department of Biotechnology, Neurochemistry and Neuroendocrinology Laboratory, Guru Nanak Dev University, Amritsar, India
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27
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Mantha SV. Mediation of L-arginine-induced retardation of hypercholesterolemic atherosclerosis in rabbits by antioxidant mechanisms. Nutr Res 1999. [DOI: 10.1016/s0271-5317(99)00109-8] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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28
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Serra H, Monteiro A, Fonteles MC. The effect of Bothrops jararaca venom on rat kidney after short-term exposure: preliminary results. PHARMACOLOGY & TOXICOLOGY 1999; 85:198-200. [PMID: 10563520 DOI: 10.1111/j.1600-0773.1999.tb00092.x] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- H Serra
- Department of Physiology and Pharmacology, Federal University of Ceara and Ceara State University, Fortaleza-Ce-Brazil
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29
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McCarty MF. The reported clinical utility of taurine in ischemic disorders may reflect a down-regulation of neutrophil activation and adhesion. Med Hypotheses 1999; 53:290-9. [PMID: 10608263 DOI: 10.1054/mehy.1998.0760] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
The first publications regarding clinical use of taurine were Italian reports claiming therapeutic efficacy in angina, intermittent claudication and symptomatic cerebral arteriosclerosis. A down-regulation of neutrophil activation and endothelial adhesion might plausibly account for these observations. Endothelial platelet-activating factor (PAF) is a crucial stimulus to neutrophil adhesion and activation, whereas endothelial nitric oxide (NO) suppresses PAF production and acts in various other ways to antagonize binding and activation of neutrophils. Hypochlorous acid (HOCl), a neutrophil product which avidly oxidizes many sulfhydryl-dependent proteins, can be expected to inhibit NO synthase while up-regulating PAF generation; thus, a vicious circle can be postulated whereby HOCl released by marginating neutrophils acts on capillary or venular endothelium to promote further neutrophil adhesion and activation. Taurine is the natural detoxicant of HOCl, and thus has the potential to intervene in this vicious circle, promoting a less adhesive endothelium and restraining excessive neutrophil activation. Agents which inhibit the action of PAF on neutrophils, such as ginkgolides and pentoxifylline, have documented utility in ischemic disorders and presumably would complement the efficacy of taurine in this regard. Fish oil, which inhibits endothelial expression of various adhesion factors and probably PAF as well, and which suppresses neutrophil leukotriene production, may likewise be useful in ischemia. These agents may additionally constitute a non-toxic strategy for treating inflammatory disorders in which activated neutrophils play a prominent pathogenic role. Double-blind studies to confirm the efficacy of taurine in symptomatic chronic ischemia are needed.
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30
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Ellemor DM, Baird RN, Awad MM, Boyd RL, Rood JI, Emmins JJ. Use of genetically manipulated strains of Clostridium perfringens reveals that both alpha-toxin and theta-toxin are required for vascular leukostasis to occur in experimental gas gangrene. Infect Immun 1999; 67:4902-7. [PMID: 10456947 PMCID: PMC96825 DOI: 10.1128/iai.67.9.4902-4907.1999] [Citation(s) in RCA: 70] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
A hallmark of gas gangrene (clostridial myonecrosis) pathology is a paucity of leukocytes infiltrating the necrotic tissue. The cause of this paucity most likely relates to the observation of leukocyte aggregates at the border of the area of tissue necrosis, often within the microvasculature itself. Infecting mice with genetically manipulated strains of Clostridium perfringens type A (deficient in either alpha-toxin or theta-toxin production) resulted in significantly reduced leukocyte aggregation when alpha-toxin was absent and complete abrogation of leukocyte aggregation when theta-toxin was absent. Thus, both alpha-toxin and theta-toxin are necessary for the characteristic vascular leukostasis observed in clostridial myonecrosis.
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Affiliation(s)
- D M Ellemor
- Department of Pathology and Immunology, Monash Medical School, Alfred Hospital, Prahran, Victoria 3181, Australia.
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31
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Titball RW, Naylor CE, Basak AK. The Clostridium perfringensα-toxin. Anaerobe 1999; 5:51-64. [PMID: 16887662 DOI: 10.1006/anae.1999.0191] [Citation(s) in RCA: 130] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/1999] [Accepted: 03/19/1999] [Indexed: 11/22/2022]
Abstract
The gene encoding the alpha-(cpa) is present in all strains of Clostridium perfringens, and the purified alpha-toxin has been shown to be a zinc-containing phospholipase C enzyme, which is preferentially active towards phosphatidylcholine and sphingomyelin. The alpha-toxin is haemolytic as a result if its ability to hydrolyse cell membrane phospholipids and this activity distinguishes it from many other related zinc-metallophospholipases C. Recent studies have shown that the alpha-toxin is the major virulence determinant in cases of gas gangrene, and the toxin might play a role in several other diseases of animals and man as diverse as necrotic enteritis in chickens and Crohn's disease in man. In gas gangrene the toxin appears to have three major roles in the pathogenesis of disease. First, it is able to cause mistrafficking of neutrophils, such that they do not enter infected tissues. Second, the toxin is able to cause vasoconstriction and platelet aggregation which might reduce the blood supply to infected tissues. Finally, the toxin is able to detrimentally modulate host cell metabolism by activating the arachidonic acid cascade and protein kinase C. The molecular structure of the alpha-toxin reveals a two domain protein. The amino-terminal domain contains the phospholipase C active site which contains zinc ions. The carboxyterminal domain is a paralogue of lipid binding domains found in eukaryotes and appears to bind phospholipids in a calcium-dependent manner. Immunisation with the non-toxic carboxyterminal domain induces protection against the alpha-toxin and gas gangrene and this polypeptide might be exploited as a vaccine. Other workers have exploited the entire toxin as the basis of an anti-tumour system.
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Affiliation(s)
- R W Titball
- Defence Evaluation and Research Agency, CBD Porton Down, Salisbury, Wiltshire, SP4 OJQ, UK.
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Abstract
BACKGROUND: Cardiac dysfunction and tissue injury during endotoxemia may be caused by increased levels of oxygen free radicals. METHODS AND RESULTS: We therefore investigated the effects of endotoxic shock on cardiac function and contractility, plasma creatine kinase (CK) activity and lactate concentration, oxyradical-producing activity of polymorphonuclear leukocytes (PMNL-CL) and white blood corpuscles, antioxidant reserve (cardiac chemiluminescence [LV-CL]), antioxidant enzyme activity (superoxide dismutase, catalase, glutathione peroxidase), cardiac malondialdehyde (MDA) concentration, a lipid peroxidation product, and hemodynamics in the absence or presence of flaxseed treatment in anesthetized dogs. Flaxseed contains lignans that have antioxidant activites and inhibit platelet-activating factor (PAF). The dogs were assigned to three groups: group I, sham control; group II, endotoxin (ET) treated (5 mg/kg intravenously); group III, ET + flaxseed (2 gm/kg/day orally) for 6 days. ET produced a decrease in cardiac function and contractility and antioxidant enzyme levels, and an increase in cardiac MDA and LV-CL, PMNL-CL, and plasma CK and lactate. Pretreatment with flaxseed attenuated the ET-induced cardiac dysfunction and cellular damage. Protection was incomplete for cardiovascular function, plasma CK, and lactate. CONCLUSIONS: These results suggest that oxyradicals and/or PAF may be involved in the deterioration of cardiovascular function and cellular integrity during ET shock and that antioxidant and anti-PAF agents may be effective in the treatment of ET shock.
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Affiliation(s)
- U Pattanaik
- Toxicology Group, College of Medicine, Saskatoon, SK, Canada
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33
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Yamada Y, Yokota M. Roles of plasma platelet-activating factor acetylhydrolase in allergic, inflammatory, and atherosclerotic diseases. JAPANESE CIRCULATION JOURNAL 1998; 62:328-35. [PMID: 9626899 DOI: 10.1253/jcj.62.328] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Platelet-activating factor (PAF) mediates a variety of physiologic and pathologic events by activating platelets, neutrophils, monocytes, macrophages, and smooth muscle cells. A strongly oxidizing environment induces fragmentation of the polyunsaturated fatty acids of membrane phospholipids, and the resulting oxidized phospholipids are structurally similar to PAF and mimic its biologic actions. The effects of PAF and oxidized phospholipids are abolished by hydrolysis of the sn-2 residue, a reaction catalyzed by PAF acetylhydrolase. Plasma and intracellular forms of PAF acetylhydrolase have been purified and characterized. The plasma form binds with high affinity to lipoproteins in plasma. Furthermore, changes in the activity of this enzyme are associated with various human diseases and animal models of human pathology, suggesting that it may play important roles in their pathogenesis. Studies that have defined the properties of this enzyme and its roles in physiologic and pathologic processes are reviewed. Such studies have provided insight into the functions of PAF and oxidized phospholipids as well as into the etiology of allergic, inflammatory, and atherosclerotic diseases.
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Affiliation(s)
- Y Yamada
- Department of Geriatric Research, National Institute for Longevity Sciences, Obu, Aichi, Japan
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McCarty MF. Nitric oxide deficiency, leukocyte activation, and resultant ischemia are crucial to the pathogenesis of diabetic retinopathy/neuropathy--preventive potential of antioxidants, essential fatty acids, chromium, ginkgolides, and pentoxifylline. Med Hypotheses 1998; 50:435-49. [PMID: 9681924 DOI: 10.1016/s0306-9877(98)90217-1] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Impaired microcirculatory perfusion appears to be crucial to the pathogenesis of both neuropathy and retinopathy in diabetics. This in turn reflects a hyperglycemically mediated perturbation of vascular endothelial function that entails overactivation of protein kinase C, reduced availability of nitric oxide, increased production of superoxide and endothelin, impaired insulin function, diminished synthesis of prostacyclin/PGE1, and increased activation and endothelial adherence of leukocytes. These dysfunctions may be addressed with a supplementation program that includes high-dose antioxidants, fish oil, gamma-linolenic acid, chromium, arginine, carnitine, and ginkgolides. Pharmaceuticals likely to be of benefit in this regard include pentoxifylline, probucol, replacement estrogens, and inhibitors of angiotensin converting enzyme and aldose reductase.
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Abstract
Experimental occlusion of a brain-supplying artery triggers tissue ischemia and subsequent inflammatory events that are initiated at the blood microvessel interface. Cytokine production and molecular adhesive events occur in the early moments following cerebral blood flow reduction, which underlie the transition from ischemic to inflammatory injury. Events both within the microvascular lumen and in the immediately surrounding tissue are involved. Cytokines, including TNF-alpha, IL-1 beta, IL-6, and PAF, are produced from the ischemic parenchyma and contribute to the endothelial cell expression of P-selectin, ICAM-1, and E-selectin. Platelet activation occurs paris passu and probably involves alpha-granule P-selectin to mediate PMN leukocyte-platelet interactions. Other integrin heterodimers are also involved in the early microvascular responses to ischemia. The response of the basal lamina and ECM is somewhat slower, entailing yet unproven mechanisms that most probably include the proteolytic processes of leukocyte transmigration. The modifications to microvascular structure are likely to affect both endothelial and astrocyte relationships, promote erythrocyte extravasation and hemorrhage, and contribute to tissue injury. Remodeling of the microvasculature, apparent in other tissues, involves a number of these processes. However, the enzymatic participants and regulating mechanisms are coming under study: the unraveling of regulatory mechanisms of adhesion receptor expression and their modulation, and the companion roles of integrins as mediators of structural integrity and intercellular signaling.
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Affiliation(s)
- G J del Zoppo
- Department of Molecular and Experimental Medicine, Scripps Research Institute, La Jolla, California 92037, USA.
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36
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Ammit AJ, O'Neill C. Studies of the nature of the binding by albumin of platelet-activating factor released from cells. J Biol Chem 1997; 272:18772-8. [PMID: 9228051 DOI: 10.1074/jbc.272.30.18772] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023] Open
Abstract
This report confirms that human umbilical vein endothelial cells activated by A23187 produce platelet-activating factor (PAF) (22.4 +/- 9.9 ng/10(6) cells/h; mean +/- S.E.). A proportion of the PAF produced (56%) was released by cells into the medium. The PAF released, however, was not detected without prior organic extraction, and the method of organic extraction was critical for detection. Extraction with 80% ethanol was not successful, but a modified methanol/chloroform extraction method was. These observations may explain some of the conflicting reports in the literature on release of PAF by activated endothelial cells. The requirements for organic extraction may reflect the nature of cell-released PAF's binding by albumin; it was observed that PAF added to identical media could be detected in a bioassay without the requirement for extraction. Such PAF was also readily degraded by PAF-acetylhydrolase added to media, while PAF released from cells was resistant to such degradation, suggesting that it was released in a "protected" configuration. Stimulation of cells was performed in media with albumin as the only extracellular macromolecule. Limited proteolytic digestion of the albumin with trypsin and pepsin showed that PAF released by cells was located exclusively between amino acids 240 and 386 (domain II), while no synthetic PAF added to media was located on this region. These results are identical to those described for the release of PAF by the early embryo. Albumin exposed to embryos had a higher thiol concentration (0.77 +/- 0.04 micromol of thiol/micromol of albumin; mean +/- S.E.) than control media to which an equivalent amount of synthetic PAF was added (0.59 +/- 0.02 micromol of thiol/micromol of albumin) (measured with Ellman's reagent). Furthermore, albumin from conditioned media was more susceptible to reduction by 10 mM dithiothreitol than control albumin, as assessed by its mobility on PAGE. The protected configuration of released PAF was caused by cell-dependent conformational changes to albumin involving cysteine-cysteine disulfide bonds. Partial reduction with dithiothreitol of albumin exposed to cells resulted in released PAF being able to be detected directly in a bioassay without the requirement for prior organic extraction.
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Affiliation(s)
- A J Ammit
- Department of Physiology, University of Sydney, Human Reproduction Unit, Royal North Shore Hospital, St. Leonards, New South Wales 2065, Australia
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Abstract
Oxygen free radicals (OFRs) have been implicated in the development of hypercholesterolemic atherosclerosis. Flax seed is the richest source of omega-3 fatty acid and lignans. omega-3 Fatty acid suppresses the production of interleukin-1 (IL-1), tumor necrosis factor (TNF) and leukotriene B4 (LTB4), and of OFRs by polymorphonuclear leukocytes (PMNLs) and monocytes. Lignans possess anti-platelet activating factor (PAF) activity and are antioxidant. PAF, IL-1, TNF and LTB4 are known to stimulate PMNLs to produce OFRs. Flaxseed would, therefore, reduce the levels of OFRs and hence would prevent the development of hypercholesterolemic atherosclerosis. The effects of dietary flax seed on a high cholesterol diet induced atherosclerosis, lipid profile and OFR-producing activity of PMNLs (PMNL-CL) were investigated in rabbits. The rabbits were divided into 4 groups: group I, control; group II, flax seed diet (7.5 g/kg daily, orally); group III, 1% cholesterol diet; and group IV, same as group III but received flax seed (7.5 g/kg daily, orally). Blood samples were collected before and after 4 and 8 weeks on their respective diets for biochemical measurements and aortae were removed at the end of 8 weeks for estimation of atherosclerotic changes. The high cholesterol diet increased the serum level of total cholesterol (TC) and PMNL-CL without altering the levels of serum triglycerides (TG). These changes were associated with a marked development of atherosclerosis in the aorta. Flax seed reduced the development of aortic atherosclerosis by 46% and reduced the PMNL-CL without significantly lowering the serum cholesterol. Flax seed in normocholesterolemic rabbits increased serum total cholesterol and decreased PMNL-CL without significantly affecting the serum TG. Modest dietary flax seed supplementation is effective in reducing hypercholesterolemic atherosclerosis markedly without lowering serum cholesterol. Its effectiveness against hypercholesterolemic atherosclerosis could be due to suppression of enhanced production of OFRs by PMNLs in hypercholesterolemia. Dietary flax seed supplementation could, therefore, prevent hypercholesterolemia-related heart attack and strokes.
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Affiliation(s)
- K Prasad
- Department of Physiology, College of Medicine, University of Saskatchewan, Saskatoon, Canada
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38
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Balestrieri ML, Servillo L, Lee T. The role of platelet-activating factor-dependent transacetylase in the biosynthesis of 1-acyl-2-acetyl-sn-glycero-3-phosphocholine by stimulated endothelial cells. J Biol Chem 1997; 272:17431-7. [PMID: 9211886 DOI: 10.1074/jbc.272.28.17431] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023] Open
Abstract
Acyl analogs of platelet-activating factor (PAF) (1-acyl-2-acetyl-sn-glycero-3-phosphocholine, acylacetyl -GPC) are the predominant products synthesized during thrombin or ionophore A23187-mediated activation of endothelial cells. However, the biosynthetic pathway responsible for the production of acylacetyl-GPC is not well understood. In the present investigation, we have demonstrated that the acyl analogs of PAF are also the major products from calf pulmonary artery endothelial cells in response to a time-dependent stimulation of ATP (10(-3) M), bradykinin (10(-8) M), or ionophore A23187 (2 microM). In addition, we have found that the CoA-independent PAF:acyllyso-GPC transacetylase recently identified by us is concurrently and transiently induced with maximal 4-fold enhancement at 5 min and returned to near basal level by 10 min treatment of endothelial cells with ATP. Acid phosphatase reduces the increased PAF:acyllyso-GPC transacetylase activity from the homogenates of ATP-activated endothelial cells. Reduced PAF:acyllyso-GPC transacetylase activity can be restored by incubating the acid phosphatase-treated homogenates with ATP (5 mM) and Mg2+ (10 mM). Furthermore, okadaic acid, a protein phosphatase 1 and 2A inhibitor, incubated with endothelial cells in a dose-dependent manner (1-100 nM) for 10-min potentiates and sustained the stimulation of PAF:acyllyso-GPC transacetylase activity by ATP. On the other hand, genistein, tyrphostin-25 (inhibitors of tyrosine-specific protein kinase), and calphostin C (an inhibitor of protein kinase C) block the activation of PAF:acyllyso-GPC transacetylase by ATP. These results are consistent with the notion that ATP regulates the transacetylase activity by reversible activation and inactivation via the phosphorylation and dephosphorylation cycle. ATP also augments the activities of alkyllyso-GPC/acyllyso-GPC:acetyl-CoA acetyltransferase. However, the activation of the acetyltransferases precedes that of the transacetylase with peak activation occurring at 1-2 min of the ATP treatment. In addition, sodium vanadate, also an inhibitor of protein phosphatase, stimulates the increase in the incorporation of [3H]acetate into acyl[3H]acetyl-GPC of the ATP-treated endothelial cells. Collectively, our data show that both acetyltransferases and transacetylase participate in and contribute to the biosynthesis of acyl analogs of PAF in a coordinate fashion in endothelial cells.
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Affiliation(s)
- M L Balestrieri
- Environmental and Health Sciences Division, Oak Ridge Associated Universities, Oak Ridge, Tennessee 37831-0117, USA
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39
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Terada LS, Hybertson BM, Connelly KG, Weill D, Piermattei D, Repine JE. XO increases neutrophil adherence to endothelial cells by a dual ICAM-1 and P-selectin-mediated mechanism. J Appl Physiol (1985) 1997; 82:866-73. [PMID: 9074976 DOI: 10.1152/jappl.1997.82.3.866] [Citation(s) in RCA: 20] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023] Open
Abstract
Circulating xanthine oxidase (XO) can modify adhesive interactions between neutrophils and the vascular endothelium, although the mechanism underlying this effect are not clear. We found that treatment with XO of bovine pulmonary artery endothelial cells (EC), but not neutrophils or plasma, increased adherence, suggesting that XO had its primary effect on EC. The mechanism by which XO increased neutrophil adherence to EC involved binding of XO to EC and production of H2O2. XO also increased platelet-activating factor production by EC by a H2O2-dependent mechanism. Similarly, the platelet-activating factor-receptor antagonist WEB-2086 completely blocked XO-mediated neutrophil EC adherence. In addition, neutrophil adherence was dependent on the beta 2-integrin Mac-1 (CD11b/CD18) but not on leukocyte functional antigen-1 (CD11a/CD18). Treatment of EC with XO for 30 min did not alter intercellular adhesion molecule-1 surface expression but increased expression of P-selectin and release of von Willibrand factor. Antibodies against P-selectin (CD62) did not affect XO-mediated neutrophil adherence under static conditions but decreased both rolling and firm adhesive interactions under conditions of shear. We conclude that extracellular XO associates with the endothelium and promotes neutrophil-endothelial cell interactions through dual intercellular adhesion molecule-1 and P-selectin ligation, by a mechanism that involves platelet-activating factor and H2O2 as intermediates.
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Affiliation(s)
- L S Terada
- Webb-Waring Institute for Biomedical Research, University of Colorado Health Sciences Center, Denver 80262, USA
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40
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Feuerstein G, Rabinovici R, Leor J, Winkler JD, Vonhof S. Platelet-activating factor and cardiac diseases: therapeutic potential for PAF inhibitors. JOURNAL OF LIPID MEDIATORS AND CELL SIGNALLING 1997; 15:255-84. [PMID: 9041476 DOI: 10.1016/s0929-7855(96)00562-7] [Citation(s) in RCA: 22] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
Platelet-activating factor (PAF) is a potent phospholipid mediator released from inflammatory cells in response to diverse immunologic and non-immunologic stimuli. Animal studies have implicated PAF as a major mediator involved in coronary artery constriction, modulation of myocardial contractility and the generation of arrhythmias which may bear on cardiac disorders such as ischemia, infarction and sudden cardiac death. PAF effects are induced by direct actions of PAF on cardiac tissue to modify chronotropic and inotropic activity, or indirectly via the release of eicosanoids such as thromboxane A2 (TXA2), leukotrienes (LT) or cytokines (TNF alpha). The development of selective, high affinity PAF receptor antagonists has permitted investigations on the role of PAF in experimental animal models of cardiac injury. In vivo and in vitro studies strongly suggest that PAF receptor antagonists might convey therapeutic benefits in ischemic conditions and certain arrhythmias. In addition, PAF antagonists might have a cardiac allograft-preservation effect. Although clinical studies with PAF receptor antagonists in patients with cardiac diseases have not yet been reported, the experimental results to date suggest that PAF receptor antagonists might be useful in some specific cardiac disorders in humans.
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Affiliation(s)
- G Feuerstein
- Department of Cardiovascular, UW2511, SmithKline Beecham Pharmaceuticals, King of Prussia, PA 19406-0939, USA
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41
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Affiliation(s)
- J M Grinyó
- Hospital Princeps d'Espanya, Ciutat Sanitària i Universitària de Bellvitge, Universitat de Barcelona, Departament de Medicina, Spain
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42
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Abstract
Necrotizing soft-tissue infections may be rapidly fatal because of toxin-induced circulatory collapse. Because of the often nonspecific clinical presentation, prompt diagnosis may be difficult but is imperative as prompt treatment can be lifesaving. This article discusses necrotizing fasciitis and clostridial myonecrosis, and highlights pathogenesis, clinical presentation, diagnosis, and treatment.
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Affiliation(s)
- E K Chapnick
- Division of Infectious Diseases, Maimonides Medical Center, Brooklyn, NY 11219, USA
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43
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Heimbürger M, Palmblad JE. Effects of leukotriene C4 and D4, histamine and bradykinin on cytosolic calcium concentrations and adhesiveness of endothelial cells and neutrophils. Clin Exp Immunol 1996; 103:454-60. [PMID: 8608646 PMCID: PMC2200372 DOI: 10.1111/j.1365-2249.1996.tb08302.x] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 11/08/1995] [Indexed: 01/31/2023] Open
Abstract
We compared the effects of leukotrienes B4, C4 and D4 (LTB4, C4 and D4) in vitro, as well as of histamine and bradykinin, on adhesive interactions between cultured umbilical vein endothelial cells (HUVEC) and polymorphonuclear neutrophils (PMN) and on cytosolic calcium transients, [Ca(2+)](i), in vitro. LTB4, but not LTC4 or LTD4 (at 1-100 nM), increased HUVEC adhesiveness for PMN, maximally 2.8 fold; in addition, PMN adhesion was augmented by LTB4 (but not by LTC4 and LTD4) to a plastic surface. Rapid, but smaller increments of HUVEC (but not of PMN) adhesiveness were induced by histamine and bradykinin (at 10 microM). Nonetheless, LTC4 and LTD4 (at 100 nm) induced rapid rises of [Ca(2+)](i) in HUVEC, whereas approximately 100-fold higher concentrations were needed of histamine and bradykinin for similar rises. In PMN LTD4 (and LTB4) induced rapid increases of [Ca(2+)](i), whereas no significant effect was seen with LTC4, histamine or bradykinin. The [Ca(2+)](i) responses to LTC4 and LTD4 were inhibited by the peptidoleukotriene receptor blocker SKF 104,353. Thus, LTB4 and the peptidoleukotrienes display disparate profiles as inducers of adhesion and calcium transients in PMN and HUVEC, indicating discrete differences in the stimulus response coupling for these closely related leukotrienes.
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Affiliation(s)
- M Heimbürger
- Department of Rheumatology, Karolinska Institute at Stockholm Söder Hospital, Sweden
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44
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Sugatani J, Miwa M, Komiyama Y, Ito S. High-density lipoprotein inhibits the synthesis of platelet-activating factor in human vascular endothelial cells. JOURNAL OF LIPID MEDIATORS AND CELL SIGNALLING 1996; 13:73-88. [PMID: 8998599 DOI: 10.1016/0929-7855(95)00047-x] [Citation(s) in RCA: 45] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
The regulation of platelet-activating factor (PAF) synthesis by serum lipoproteins was investigated in human umbilical vein endothelial cells. High-density lipoprotein (HDL) inhibited PAF synthesis in agonist (thrombin, histamine, and A23187)-stimulated endothelial cells, that was determined by incorporation of [3H]acetate into PAF and by bioassay. The inhibition by HDL was increased in a concentration-dependent manner, but was reversed as the concentration of thrombin increased. HDL did not affect the time course of PAF production. HDL lipids suppressed the PAF production to a lesser extent than HDL. The reduction of PAF accumulation in HDL, did not result from degradation of PAF but inhibition of PAF synthesis, which was mainly mediated via the blockade of acetyl-CoA:1-alkyl-2-lyso-sn-glycero-3-phosphocholine acetyltransferase activation. HDL did not prevent the release of [3H]arachidonic acid in thrombin-stimulated endothelial cells. The binding of 125I-HDL to endothelial cells and its uptake were not enhanced by thrombin stimulation. These results demonstrate that HDL may inhibit the activation of acetyltransferase by thrombin at the cell surface. This observation may explain a part of mechanism of HDL action.
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Affiliation(s)
- J Sugatani
- Department of Medical Chemistry, Kansai Medical University, Osaka, Japan
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45
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Tjoelker LW, Eberhardt C, Unger J, Trong HL, Zimmerman GA, McIntyre TM, Stafforini DM, Prescott SM, Gray PW. Plasma platelet-activating factor acetylhydrolase is a secreted phospholipase A2 with a catalytic triad. J Biol Chem 1995; 270:25481-7. [PMID: 7592717 DOI: 10.1074/jbc.270.43.25481] [Citation(s) in RCA: 181] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023] Open
Abstract
Platelet-activating factor (PAF) is a potent pro-inflammatory autacoid with diverse physiological and pathological actions. These actions are modulated by PAF acetylhydrolase, which hydrolyzes the sn-2 ester bond to yield the biologically inactive lyso-PAF. In contrast to most secreted phospholipase A2s, plasma PAF acetylhydrolase is calcium-dependent and contains a GXSXG motif that is characteristic of the neutral lipases and serine esterases. In this study we tested whether the serine in this motif is part of the active site of plasma PAF acetylhydrolase and, if so, what the other components of the active site are. Using site-directed mutagenesis, we demonstrated that Ser-273 (of the GXSXG motif), Asp-296, and His-351 are essential for catalysis. These residues were conserved in PAF acetylhydrolase sequences isolated from bovine, dog, mouse, and chicken. The linear orientation and spacing of these catalytic residues are consistent with the alpha/beta hydrolase conformation of other lipases and esterases. In support of this model, analysis of systematic truncations of PAF acetylhydrolase revealed that deletions beyond 54 amino acids from the NH2 terminus and 21 from the COOH terminus resulted in a loss of enzyme activity. These observations demonstrate that although plasma PAF acetylhydrolase is a phospholipase A2 it has structural properties characteristic of the neutral lipases and esterases.
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Affiliation(s)
- L W Tjoelker
- ICOS Corporation, Bothell, Washington 98021, USA
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46
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Bussolino F, Soldi R, Arese M, Jaranowska A, Sogos V, Gremo F. Multiple roles of platelet-activating factor in the nervous system. Neurochem Int 1995; 26:425-33. [PMID: 7492940 DOI: 10.1016/0197-0186(94)00137-j] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
Affiliation(s)
- F Bussolino
- Dipartimento di Genetica, Biologia e Chimica Medica, Universitá di Torino, Italy
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47
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Bussolino F, Camussi G. Platelet-Activating Factor Produced by Endothelial Cells. A Molecule with Autocrine and Paracrine Properties. ACTA ACUST UNITED AC 1995. [DOI: 10.1111/j.1432-1033.1995.tb20472.x] [Citation(s) in RCA: 65] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
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48
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49
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Hashikura Y, Kawasaki S, Matsunami H, Ikegami T, Nakazawa Y, Makuuchi M. Effect of platelet-activating factor on cold-preserved liver grafts. Br J Surg 1994; 81:1779-82. [PMID: 7827938 DOI: 10.1002/bjs.1800811223] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
Platelet-activating factor (PAF) may play an important role in graft injury in liver transplantation. Livers excised from male Wistar rats were preserved in University of Wisconsin solution for 6 h and then perfused with Krebs-Henseleit solution containing vehicle (bovine serum albumin) or PAF. Impairment of parenchymal cells was assessed by reference to tissue adenosine triphosphate levels, oxygen consumption and alanine aminotransferase activity in the effluent. The effect on non-parenchymal cells was evaluated by measurement of purine nucleoside phosphorylase and alanine aminotransferase levels in the effluent. Administration of as little as 1.0 ng kg-1 PAF caused a significant decrease in adenosine 5'-triphosphate concentration and oxygen consumption (P < 0.05), although non-parenchymal cell injury was not affected. PAF can therefore cause liver graft dysfunction with hepatocytes as the main target, even in the absence of microcirculatory disturbance secondary to interaction between blood cells and endothelial cells.
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Affiliation(s)
- Y Hashikura
- First Department of Surgery, Shinshu University School of Medicine, Matsumoto, Japan
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50
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Bussolino F, Arese M, Silvestro L, Soldi R, Benfenati E, Sanavio F, Aglietta M, Bosia A, Camussi G. Involvement of a serine protease in the synthesis of platelet-activating factor by endothelial cells stimulated by tumor necrosis factor-alpha or interleukin-1 alpha. Eur J Immunol 1994; 24:3131-9. [PMID: 7805742 DOI: 10.1002/eji.1830241233] [Citation(s) in RCA: 26] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
It has been shown that production of platelet-activating factor (PAF, 1-O-alkyl-2-acetyl-sn-glycero-3-phosphocholine) by endothelial cells (EC) stimulated with tumor necrosis factor (TNF)-alpha and interleukin (IL)-1 alpha requires the synthesis of new proteins and is regulated by anti-proteinases. Here, we demonstrate that TNF-alpha and IL-1 alpha induce the expression by EC of a 34-kDa diisopropyl fluorophosphate-binding protein immunoprecipitated by an anti-human elastase antibody. This protein is released in the medium and cleaves the chromogenic substrate N-methoxysuccinyl- Ala-Ala-Pro-Val p-anilide, which is specific for elastase. The generation of this elastase-like protein seems to be important for the synthesis of PAF induced by TNF-alpha and IL-1 alpha, as suggested by the following observations: (a) it precedes the synthesis of PAF; (b) the inhibitors of serine protease and anti-human elastase antibody prevent the synthesis of PAF and the activation of 1-O-alkyl-2-lyso-glycerophosphocholine acetyl-CoA: acetyltransferase, which is a key enzyme of the PAF remodelling pathway; (c) elastase, at concentrations similar to that detectable in the medium of cytokine-activated EC, elicits a rapid synthesis of PAF by EC. High-performance liquid chromatography-tandem mass spectrometric analysis of bioactive PAF demonstrates that the molecular species produced after stimulation of EC with TNF-alpha, IL-1 alpha or elastase are similar, with a predominant synthesis of the alkyl species. These results indicate that TNF-alpha and IL-1 alpha stimulate the production of a serine protease which is critical in the activation of enzymes involved in PAF synthesis, suggesting the potential involvement of this mechanism in the regulation of EC functions.
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Affiliation(s)
- F Bussolino
- Dipartimento di Genetica Biologia e Chimica Medica, Università di Torino, Italy
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