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Donahue TJ, Hillhouse TM, Webster KA, Young R, De Oliveira EO, Porter JH. Examination of the mechanisms underlying the discriminative stimulus properties of the atypical antipsychotic amisulpride. Behav Pharmacol 2024; 35:47-54. [PMID: 38375659 DOI: 10.1097/fbp.0000000000000760] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/21/2024]
Abstract
Amisulpride is an atypical benzamide antipsychotic/antidepressant, whose mechanism of action is thought to depend mainly on dopamine D2/3 receptor activity, but also with some serotonin 5-HT2B/7 effects. The present study examined the role of D2/3 receptors and 5-HT2B/7 receptors in amisulpride's discriminative stimulus. Selective agonists and antagonists of the above receptors were tested in adult, male C57BL/6 mice trained to discriminate 10 mg/kg amisulpride from vehicle in a two-lever drug discrimination assay. After acquisition of the two-lever discrimination, the amisulpride generalization curve yielded an ED50 = 0.56 mg/kg (95% CI = 0.42-0.76 mg/kg). Substitution tests found that the D2/3 antagonist raclopride (62.7% Drug Lever Responding), D2/3 agonist quinpirole (56.6% DLR), 5-HT7 agonist LP-44 (50.1% DLR) and 5-HT7 antagonist SB-269970 (36.7% DLR) produced various degrees of partial substitution for the amisulpride stimulus, whereas the 5-HT2B agonist BW 723C86 (17.9% DLR) and 5-HT2B antagonist SB-204741 (21.1% DLR) yielded negligible amisulpride-like effects. In combination tests with amisulpride, quinpirole decreased percent responding from 98.3% to 57.0% DLR, LP-44 decreased percent responding from 97.6% to 76.7% DLR, and BW 723C86 reduced percent responding from 95.66% to 74.11% DLR. Taken together, the results from stimulus generalization and antagonism studies suggest that amisulpride has a complex discriminative cue that involves mainly mixed D2/3 receptor antagonist/agonist effects and, to a lesser degree, mixed 5-HT7 receptor agonist/antagonist and perhaps 5-HT2B receptor antagonist effects.
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Affiliation(s)
- Timothy J Donahue
- Department of Psychology, Virginia Commonwealth University, Richmond, Virginia
| | - Todd M Hillhouse
- Department of Psychology, University of Wisconsin - Green Bay, Green Bay, Wisconsin
| | | | - Richard Young
- Department of Medicinal Chemistry, Virginia Commonwealth University
| | | | - Joseph H Porter
- Department of Psychology, Virginia Commonwealth University, Richmond, Virginia
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Abstract
This chapter focuses on the translational value of drug discrimination as a preclinical assay for drug development. In particular, the importance of two factors, i.e., training dose and species, for drug discrimination studies with the atypical antipsychotic clozapine is examined. Serotonin receptors appear to be an important pharmacological mechanism mediating clozapine's discriminative cue in both rats and mice, although differences are clearly evident as antagonism of cholinergic muscarinic receptors is important in rats at a higher training dose (5.0 mg/kg) of clozapine, but not at a lower training dose (1.25 mg/kg). Antagonism of α1 adrenoceptors is a sufficient mechanism in C57BL/6 and 129S2 mice to mimic clozapine's cue, but not in DBA/2 and B6129S mice, and only produces partial substitution in low-dose clozapine discrimination in rats. Dopamine antagonism produces partial substitution for clozapine in DBA/2, 129S2, and B6129S mice, but not in C57BL/6 mice, and partial substitution is seen with D4 antagonism in low-dose clozapine drug discrimination in rats. Thus, it is evident that clozapine has a complex mixture of receptor contributions towards its discriminative cue based on the data from the four mouse strains that have been tested that is similar to the results from rat studies. A further examination of antipsychotic stimulus properties in humans, particularly in patients with schizophrenia, would go far in evaluating the translational value of the drug discrimination paradigm for antipsychotic drugs.
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Affiliation(s)
- Joseph H Porter
- Department of Psychology, Virginia Commonwealth University, Richmond, VA, 23284, USA.
| | - Kevin A Webster
- Department of Psychology, Virginia Commonwealth University, Richmond, VA, 23284, USA
| | - Adam J Prus
- Department of Psychology, Northern Michigan University, Marquette, MI, USA
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Donahue TJ, Hillhouse TM, Webster KA, Young R, De Oliveira EO, Porter JH. Discriminative stimulus properties of the atypical antipsychotic amisulpride: comparison to its isomers and to other benzamide derivatives, antipsychotic, antidepressant, and antianxiety drugs in C57BL/6 mice. Psychopharmacology (Berl) 2017; 234:3507-3520. [PMID: 28921163 DOI: 10.1007/s00213-017-4738-y] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/31/2017] [Accepted: 09/07/2017] [Indexed: 01/25/2023]
Abstract
RATIONALE Racemic (RS)-amisulpride (Solian®) is an atypical antipsychotic drug used to treat schizophrenia and dysthymia. Blockade of dopamine D2/D3 and/or serotonin 5-HT7 receptors is implicated in its pharmacological effects. While the (S)-amisulpride isomer possesses a robust discriminative cue, discriminative stimulus properties of (RS)-amisulpride have not been evaluated. OBJECTIVES The present study established (RS)-amisulpride as a discriminative stimulus and assessed amisulpride-like effects of amisulpride stereoisomers, other benzamide derivatives, and antipsychotic, antidepressant, and anxiolytic drugs. METHODS Adult, male C57BL/6 mice were trained to discriminate 10 mg/kg (RS)-amisulpride from vehicle in a two-lever food-reinforced operant conditioning task. RESULTS (RS)-Amisulpride's discriminative stimulus was dose-related, time-dependent, and stereoselective. (S)-Amisulpride (an effective dose of 50% (ED50) = 0.21 mg/kg) was three times more potent than (RS)-amisulpride (ED50 = 0.60 mg/kg) or (R)-amisulpride (ED50 = 0.68 mg/kg). (RS)-Amisulpride generalized fully to the structurally related atypical antipsychotic/antidysthymia drug sulpiride (Sulpor®; ED50 = 7.29 mg/kg) and its (S)-enantiomer (ED50 = 9.12 mg/kg); moderate to high partial generalization [60-75% drug lever responding (%DLR)] occurred to the benzamide analogs tiapride (Tiapridal®) and raclopride, but less than 60% DLR to metoclopramide (Reglan®), nemonapride (Emilace®), and zacopride. Antipsychotic, antidepressant, and antianxiety drugs from other chemical classes (chlorpromazine, quetiapine, risperidone, and mianserin) produced 35-55% amisulpride lever responding. Lastly, less than 35% DLR occurred for clozapine, olanzapine, aripiprazole imipramine, chlordiazepoxide, and bupropion. CONCLUSIONS (RS)-Amisulpride generalized to some, but not all benzamide derivatives, and it failed to generalize to any other antipsychotic, antidepressant, or antianxiety drugs tested. Interestingly, the (R)-isomer shared very strong stimulus properties with (RS)-amisulpride. This finding was in contrast to findings from Donahue et al. (Eur J Pharmacol 734:15-22, 2014), which found that the (R)-isomer did not share very strong stimulus properties when the (S)-isomer was the training drug.
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Affiliation(s)
- Timothy J Donahue
- Department of Psychology, Virginia Commonwealth University, 806 West Franklin Street, PO Box 842018, Richmond, VA, 23284-2018, USA
| | - Todd M Hillhouse
- Department of Psychology, Weber State University, Ogden, UT, USA
| | - Kevin A Webster
- Department of Psychology, Virginia Commonwealth University, 806 West Franklin Street, PO Box 842018, Richmond, VA, 23284-2018, USA
| | - Richard Young
- Department of Medicinal Chemistry, Virginia Commonwealth University, Richmond, VA, USA
| | - Eliseu O De Oliveira
- Department of Chemical and Life Science Engineering, Virginia Commonwealth University, Richmond, VA, USA
| | - Joseph H Porter
- Department of Psychology, Virginia Commonwealth University, 806 West Franklin Street, PO Box 842018, Richmond, VA, 23284-2018, USA.
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Farrell MS, McCorvy JD, Huang XP, Urban DJ, White KL, Giguere PM, Doak AK, Bernstein AI, Stout KA, Park SM, Rodriguiz RM, Gray BW, Hyatt WS, Norwood AP, Webster KA, Gannon BM, Miller GW, Porter JH, Shoichet BK, Fantegrossi WE, Wetsel WC, Roth BL. In Vitro and In Vivo Characterization of the Alkaloid Nuciferine. PLoS One 2016; 11:e0150602. [PMID: 26963248 PMCID: PMC4786259 DOI: 10.1371/journal.pone.0150602] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2015] [Accepted: 02/17/2016] [Indexed: 01/05/2023] Open
Abstract
Rationale The sacred lotus (Nelumbo nucifera) contains many phytochemicals and has a history of human use. To determine which compounds may be responsible for reported psychotropic effects, we used in silico predictions of the identified phytochemicals. Nuciferine, an alkaloid component of Nelumbo nucifera and Nymphaea caerulea, had a predicted molecular profile similar to antipsychotic compounds. Our study characterizes nuciferine using in vitro and in vivo pharmacological assays. Methods Nuciferine was first characterized in silico using the similarity ensemble approach, and was followed by further characterization and validation using the Psychoactive Drug Screening Program of the National Institute of Mental Health. Nuciferine was then tested in vivo in the head-twitch response, pre-pulse inhibition, hyperlocomotor activity, and drug discrimination paradigms. Results Nuciferine shares a receptor profile similar to aripiprazole-like antipsychotic drugs. Nuciferine was an antagonist at 5-HT2A, 5-HT2C, and 5-HT2B, an inverse agonist at 5-HT7, a partial agonist at D2, D5 and 5-HT6, an agonist at 5-HT1A and D4 receptors, and inhibited the dopamine transporter. In rodent models relevant to antipsychotic drug action, nuciferine blocked head-twitch responses and discriminative stimulus effects of a 5-HT2A agonist, substituted for clozapine discriminative stimulus, enhanced amphetamine induced locomotor activity, inhibited phencyclidine (PCP)-induced locomotor activity, and rescued PCP-induced disruption of prepulse inhibition without induction of catalepsy. Conclusions The molecular profile of nuciferine was similar but not identical to that shared with several approved antipsychotic drugs suggesting that nuciferine has atypical antipsychotic-like actions.
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Affiliation(s)
- Martilias S. Farrell
- Department of Pharmacology, University of North Carolina School of Medicine, Chapel Hill, North Carolina, United States of America
- * E-mail:
| | - John D. McCorvy
- Department of Pharmacology, University of North Carolina School of Medicine, Chapel Hill, North Carolina, United States of America
| | - Xi-Ping Huang
- Department of Pharmacology, University of North Carolina School of Medicine, Chapel Hill, North Carolina, United States of America
- National Institute of Mental Health Psychoactive Drug Screening Program, University of North Carolina School of Medicine, Chapel Hill, North Carolina, United States of America
| | - Daniel J. Urban
- Department of Pharmacology, University of North Carolina School of Medicine, Chapel Hill, North Carolina, United States of America
| | - Kate L. White
- Department of Pharmacology, University of North Carolina School of Medicine, Chapel Hill, North Carolina, United States of America
| | - Patrick M. Giguere
- Department of Pharmacology, University of North Carolina School of Medicine, Chapel Hill, North Carolina, United States of America
| | - Allison K. Doak
- Department of Pharmaceutical Chemistry, University of California San Francisco, San Francisco, California, United States of America
| | - Alison I. Bernstein
- Department of Environmental Health, Rollins School of Public Health and Center for Neurodegenerative Diseases, Emory University, Atlanta, Georgia, United States of America
| | - Kristen A. Stout
- Department of Environmental Health, Rollins School of Public Health and Center for Neurodegenerative Diseases, Emory University, Atlanta, Georgia, United States of America
| | - Su Mi Park
- Departments of Psychiatry and Behavioral Sciences, Cell Biology, and Neurobiology, Mouse Behavioral and Neuroendocrine Analysis Core Facility, Duke University Medical Center, Durham, North Carolina, United States of America
| | - Ramona M. Rodriguiz
- Departments of Psychiatry and Behavioral Sciences, Cell Biology, and Neurobiology, Mouse Behavioral and Neuroendocrine Analysis Core Facility, Duke University Medical Center, Durham, North Carolina, United States of America
| | - Bradley W. Gray
- Department of Pharmacology and Toxicology, University of Arkansas for Medical Sciences, Little Rock, Arkansas, United States of America
| | - William S. Hyatt
- Department of Pharmacology and Toxicology, University of Arkansas for Medical Sciences, Little Rock, Arkansas, United States of America
| | - Andrew P. Norwood
- Department of Pharmacology and Toxicology, University of Arkansas for Medical Sciences, Little Rock, Arkansas, United States of America
| | - Kevin A. Webster
- Department of Psychology, Virginia Commonwealth University, Richmond, Virginia, United States of America
| | - Brenda M. Gannon
- Department of Pharmacology and Toxicology, University of Arkansas for Medical Sciences, Little Rock, Arkansas, United States of America
| | - Gary W. Miller
- Department of Environmental Health, Rollins School of Public Health and Center for Neurodegenerative Diseases, Emory University, Atlanta, Georgia, United States of America
| | - Joseph H. Porter
- Department of Psychology, Virginia Commonwealth University, Richmond, Virginia, United States of America
| | - Brian K. Shoichet
- Department of Pharmaceutical Chemistry, University of California San Francisco, San Francisco, California, United States of America
| | - William E. Fantegrossi
- Department of Pharmacology and Toxicology, University of Arkansas for Medical Sciences, Little Rock, Arkansas, United States of America
| | - William C. Wetsel
- Departments of Psychiatry and Behavioral Sciences, Cell Biology, and Neurobiology, Mouse Behavioral and Neuroendocrine Analysis Core Facility, Duke University Medical Center, Durham, North Carolina, United States of America
| | - Bryan L. Roth
- Department of Pharmacology, University of North Carolina School of Medicine, Chapel Hill, North Carolina, United States of America
- Department of Psychiatry, University of North Carolina School of Medicine, Chapel Hill, North Carolina, United States of America
- Program in Neuroscience, University of North Carolina School of Medicine, Chapel Hill, North Carolina, United States of America
- Lineberger Comprehensive Cancer Center, University of North Carolina School of Medicine, Chapel Hill, North Carolina, United States of America
- Carolina Institute for Developmental Disabilities, University of North Carolina School of Medicine, Chapel Hill, North Carolina, United States of America
- Division of Chemical Biology and Medicinal Chemistry, School of Pharmacy, University of North Carolina School of Medicine, Chapel Hill, North Carolina, United States of America
- National Institute of Mental Health Psychoactive Drug Screening Program, University of North Carolina School of Medicine, Chapel Hill, North Carolina, United States of America
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Webster KA, Vincent L, Docherty CA. 56 Peak plantar pressures during walking in chronic ankle instability and healthy patients. Br J Sports Med 2015. [DOI: 10.1136/bjsports-2015-095573.56] [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: 11/03/2022]
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Donahue TJ, Hillhouse TM, Webster KA, Young R, De Oliveira EO, Porter JH. (S)-amisulpride as a discriminative stimulus in C57BL/6 mice and its comparison to the stimulus effects of typical and atypical antipsychotics. Eur J Pharmacol 2014; 734:15-22. [DOI: 10.1016/j.ejphar.2014.03.047] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2013] [Revised: 03/10/2014] [Accepted: 03/20/2014] [Indexed: 11/28/2022]
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Chopra I, Li HF, Wang H, Webster KA. Phosphorylation of the insulin receptor by AMP-activated protein kinase (AMPK) promotes ligand-independent activation of the insulin signalling pathway in rodent muscle. Diabetologia 2012; 55:783-94. [PMID: 22207502 PMCID: PMC4648248 DOI: 10.1007/s00125-011-2407-y] [Citation(s) in RCA: 84] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/10/2011] [Accepted: 11/10/2011] [Indexed: 01/22/2023]
Abstract
AIMS/HYPOTHESIS Muscle may experience hypoglycaemia during ischaemia or insulin infusion. During severe hypoglycaemia energy production is blocked, and an increase of AMP:ATP activates the energy sensor and putative insulin-sensitiser AMP-activated protein kinase (AMPK). AMPK promotes energy conservation and survival by shutting down anabolism and activating catabolic pathways. We investigated the molecular mechanism of a unique glucose stress defence pathway involving AMPK-dependent, insulin-independent activation of the insulin signalling pathway. METHODS Cardiac or skeletal myocytes were subjected to glucose and insulin-free incubation for increasing intervals up to 20 h. AMPK, and components of the insulin signalling pathway and their targets were quantified by western blot using phosphor-specific antibodies. Phosphomimetics were used to determine the function of IRS-1 Ser789 phosphorylation and in vitro [³²P]ATP kinase assays were used to measure the phosphorylation of the purified insulin receptor by AMPK. RESULTS Glucose deprivation increased Akt-Thr308 and Akt-Ser473 phosphorylation by almost tenfold. Phosphorylation of glycogen synthase kinase 3 beta increased in parallel, but phosphorylation of ribosomal 70S subunit-S6 protein kinase and mammalian target of rapamycin decreased. AMPK inhibitors blocked and aminoimidazole carboxamide ribonucleotide (AICAR) mimicked the effects of glucose starvation. Glucose deprivation increased the phosphorylation of IRS-1 on serine-789, but phosphomimetics revealed that this conferred negative regulation. Glucose deprivation enhanced tyrosine phosphorylation of IRS-1 and the insulin receptor, effects that were blocked by AMPK inhibition and mimicked by AICAR. In vitro kinase assays using purified proteins confirmed that the insulin receptor is a direct target of AMPK. CONCLUSIONS/INTERPRETATION AMPK phosphorylates and activates the insulin receptor, providing a direct link between AMPK and the insulin signalling pathway; this pathway promotes energy conservation and survival of muscle exposed to severe glucose deprivation.
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MESH Headings
- AMP-Activated Protein Kinases/antagonists & inhibitors
- AMP-Activated Protein Kinases/metabolism
- Animals
- Animals, Newborn
- Cells, Cultured
- Hep G2 Cells
- Humans
- Hypoglycemia/metabolism
- Hypoglycemic Agents/pharmacology
- Insulin Receptor Substrate Proteins/genetics
- Insulin Receptor Substrate Proteins/metabolism
- Ligands
- Muscle, Skeletal/cytology
- Muscle, Skeletal/drug effects
- Muscle, Skeletal/metabolism
- Mutant Proteins/metabolism
- Myocytes, Cardiac/cytology
- Myocytes, Cardiac/drug effects
- Myocytes, Cardiac/metabolism
- Phosphorylation/drug effects
- Protein Kinase Inhibitors/pharmacology
- Protein Processing, Post-Translational/drug effects
- Rats
- Receptor, Insulin/isolation & purification
- Receptor, Insulin/metabolism
- Recombinant Proteins/metabolism
- Signal Transduction/drug effects
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Affiliation(s)
- I Chopra
- Department of Molecular and Cellular Pharmacology, University of Miami Miller School of Medicine, 1600 NW 10th Ave, RMSB 6038, Miami, FL 33136, USA
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Prentice HM, Moench IA, Rickaway ZT, Dougherty CJ, Webster KA, Weissbach H. MsrA protects cardiac myocytes against hypoxia/reoxygenation induced cell death. Biochem Biophys Res Commun 2007; 366:775-8. [PMID: 18083115 DOI: 10.1016/j.bbrc.2007.12.043] [Citation(s) in RCA: 47] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2007] [Accepted: 12/04/2007] [Indexed: 01/30/2023]
Abstract
Reactive oxygen species (ROS) are critical in tissue responses to ischemia-reperfusion. The enzyme methionine sulfoxide reductase-A (MsrA) is capable of protecting cells against oxidative damage by reversing damage to proteins caused by methionine oxidation or by decreasing ROS through a scavenger mechanism. The current study employed adenovirus mediated over-expression of MsrA in primary neonatal rat cardiac myocytes to determine the effect of this enzyme in protecting against hypoxia/reoxygenation in this tissue. Cells were transduced with MsrA encoding adenovirus and subjected to hypoxia/reoxygenation. Apoptotic cell death was decreased by greater than 45% in cells over-expressing MsrA relative to cells transduced with a control virus. Likewise total cell death as determined by levels of LDH release was dramatically decreased by MsrA over-expression. These observations indicate that MsrA is protective against hypoxia/reoxygenation stress in cardiac myocytes and point to MsrA as an important therapeutic target for ischemic heart disease.
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Affiliation(s)
- H M Prentice
- Florida Atlantic University, College of Biomedical Science, 777 Glades Road, Boca Raton, FL 33431, USA
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Gounis MJ, Spiga MG, Graham RM, Wilson A, Haliko S, Lieber BB, Wakhloo AK, Webster KA. Angiogenesis is confined to the transient period of VEGF expression that follows adenoviral gene delivery to ischemic muscle. Gene Ther 2005; 12:762-71. [PMID: 15772688 DOI: 10.1038/sj.gt.3302481] [Citation(s) in RCA: 54] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Therapeutic angiogenesis involves the introduction of exogenous growth factor proteins and genes into ischemic tissues to augment endogenous factors and promote new vessel growth. Positive results from studies in animal models of peripheral arterial disease (PAD) and coronary artery disease over the past decade have supported the implementation of clinical trials testing vascular endothelial growth factor (VEGF) and fibroblast growth factor (FGF) proteins and genes. Although several clinical trials reported positive results, others have been disappointing and results of a recent Phase II trial of VEGF delivered by adenovirus (the RAVE trial) were negative. It has been suggested that the duration of gene expression following delivery by adenovirus may be insufficient to produce stable vessels. Here we present direct evidence in support of this using the rabbit ischemic hindlimb model injected with adenovirus encoding VEGF165. Immunohistology indicated an activation of endothelial cell cycling and proliferation 2-3 days after VEGF delivery that coincided closely with transient VEGF expression. Ki-67-positive endothelial nuclei were evident at high levels in capillaries and large vessels in muscles from treated animals. Angiography indicated increased density of both large and small vessels in Ad-VEGF-treated muscle at 1 week, but no significant differences thereafter. The early burst of endothelial proliferation was accompanied by increased nuclear fragmentation and condensation in VEGF-treated muscles, suggesting coincident apoptosis. No further endothelial cell proliferation took place after 1 week although there was still evidence of apoptosis. The results suggest that angiogenesis is confined to the short period of VEGF expression produced by adenovirus and early gains in collateralization rapidly regress to control levels when VEGF production ceases.
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Affiliation(s)
- M J Gounis
- The Vascular Biology Institute, University of Miami School of Medicine, Miami, FL, USA
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Abstract
Cryptosporidiosis is a zoonotic disease caused by a parasitic protozoan belonging to the coccidial genus Cryptosporidium. Current laboratory methods are adequate for the detection of the infection when oocysts are present in great numbers, but more-sensitive means of identification are urgently required. In a recent issue of Parasitology Today, Carolyn Petersen has presented a review of the cell biology of this parasite'. Here, Kath Webster draws attention to the various methods involved in its detection and classification.
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Affiliation(s)
- K A Webster
- Central Veterinary Laboratory, Woodham Lane, New Haw, Weybridge, UK KT 15 3NB
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Gile M, Warhurst DC, Webster KA, West DM, Marshall JA. A multiplex allele specific polymerase chain reaction (MAS-PCR) on the dihydrofolate reductase gene for the detection of Cryptosporidium parvum genotypes 1 and 2. Parasitology 2002; 125:35-44. [PMID: 12166518 DOI: 10.1017/s0031182002001786] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.1] [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: 12/19/2022]
Abstract
A multiplex allele specific polymerase chain reaction (MAS-PCR) based on the Cryptosporidium parvum dihydrofolate reductase (dhfr) gene sequence differentiates genotype 1 ('Human') from 2 ('Cattle') in a 1-step reaction. The MAS-PCR was validated on a panel of 34 microscopically positive C. parvum faecal samples of human and animal origin in comparison with 2 published PCR-restriction fragment length polymorphism (RFLP) methods targeting dhfr and the oocyst wall protein (cowp) genes. A validation panel of 37 negative faecal samples of human and animal origin was also tested in comparison with the cowp PCR-RFLP. MAS-PCR was found to be as sensitive for species detection as the most sensitive of the other tests, and detected more mixed genotype infections than the two other tests combined. In addition the MAS-PCR showed equivalent detection sensitivity in comparison with a published nested RFLP targeting the SSU rRNA gene, on a panel of prepared mixed genotype samples. The 1-step reaction is simpler and less expensive to perform than the RFLP methods, while the C. parvum specific amplicons and those for genotypes 1 and 2 (575, 357 and 190 bp respectively) can be easily distinguished on agarose gel.
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Affiliation(s)
- M Gile
- Biotechnology Department, Veterinary Laboratories Agency, Addlestone, Surrey, UK.
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Affiliation(s)
- M Giles
- Veterinary Laboratories Agency--Weybridge, Addlestone, Surrey
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Abstract
Redox-sensitive cysteine residues are present in the interaction domains of many protein complexes. There are examples in all of the major categories of transcription factors, including basic region, leucine zipper, helix-loop-helix, and zinc finger. Zinc finger structures require at least two zinc-coordinated cysteine sulfhydryl groups, and oxidation or alkylation of these can eliminate DNA-binding and transcriptional functions. We review here the evidence for oxidation of zinc finger cysteines, the pathways and reactive oxygen intermediates involved, and the functional and physiological consequences of these reactions. Despite skepticism that the strongly reducing intracellular environment would permit significant oxidation of cysteine residues within zinc finger transcription factors, there is compelling evidence that oxidation occurs both in vitro and in vivo. Early reports demonstrating reversible oxidation of zinc-coordinated cysteines with loss of binding function in vitro were shown to reflect accurately the changes in intact cells, and these in turn have been shown to correlate with physiological changes. In particular, the accumulation of oxidized Spl zinc fingers during aging, and estrogen receptors in tamoxifen-resistant breast cancers are dramatic examples of what may be a general sensitivity of zinc finger factors to changes in the redox state of the cell.
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Affiliation(s)
- K A Webster
- Department of Molecular and Cellular Pharmacology, University of Miami Medical Center, FL 33136, USA.
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Yamashita K, Discher DJ, Hu J, Bishopric NH, Webster KA. Molecular regulation of the endothelin-1 gene by hypoxia. Contributions of hypoxia-inducible factor-1, activator protein-1, GATA-2, AND p300/CBP. J Biol Chem 2001; 276:12645-53. [PMID: 11278891 DOI: 10.1074/jbc.m011344200] [Citation(s) in RCA: 263] [Impact Index Per Article: 11.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023] Open
Abstract
Endothelin-1 (ET-1) is a peptide hormone with potent vasoconstrictor properties which is synthesized and secreted predominantly by vascular endothelial cells. Its production is regulated by numerous stimuli including ischemia and hypoxia, and the enhanced levels that occur during myocardial ischemia may contribute to the progression of heart failure. We reported previously a preliminary characterization of a hypoxia-inducible factor-1 (HIF-1) binding site in the human ET-1 promoter which contributed to the activation of ET-1 expression in endothelial cells. We report here that the HIF-1 binding site alone is not sufficient for the response to hypoxia but requires an additional 50 base pairs of flanking sequence that includes binding sites for the factors activator protein-1 (AP-1), GATA-2, and CAAT-binding factor (NF-1). Mutation of any one of these sites or the HIF-1 site eliminated induction by hypoxia. Mutations of the AP-1 and GATA-2 sites, but not the HIF-1 site, were complemented by overexpressing AP-1, GATA-2, HIF-1alpha, or the activator protein p300/CBP, restoring the response to hypoxia. Binding studies in vitro confirmed physical associations among GATA-2, AP-1, and HIF-1 factors. Overexpression or depletion of p300/CBP modulated the level of ET-1 promoter expression as well as the endogenous ET-1 transcript but did not change the fold induction by hypoxia in either case. Regulation of the ET-1 promoter by hypoxia in non-endothelial cells required overexpression of GATA-2 and HIF-1alpha. The results support essential roles for AP-1, GATA-2, and NF-1 in stabilizing the binding of HIF-1 and promoting recruitment of p300/CBP to the ET-1 hypoxia response complex.
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Affiliation(s)
- K Yamashita
- Department of Molecular and Cellular Pharmacology, University of Miami Medical Center, Miami, Florida 33149, USA
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Webster KA. Therapeutic angiogenesis: a case for targeted, regulated gene delivery. Crit Rev Eukaryot Gene Expr 2001; 10:113-25. [PMID: 11186327] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/19/2023]
Abstract
Blood and vascular disorders underlie a plethora of pathological conditions and are the single most frequent cause of human disease. Eliminated or restricted blood flow to tissues as a result of vessel dysfunction results in the disruption of oxygen and nutrient delivery and the accumulation of waste metabolites. Cells cannot survive extended severe ischemia but may be able to adapt to a moderate condition where diffusion to and from bordering nonischemic regions sustain vital functions. Under this condition, secondary functions of affected cells are likely to be impaired and a new metabolic equilibrium is established, determined by the level of cross-diffusion. In tissues with a normally high metabolic turnover such as skeletal and cardiac muscle, ischemia causes hypoxia, acidosis, and depressed function (contractility). The treatment possibilities for tissue ischemia resulting from vascular disease are limited. Lipid-lowering agents may help slow the progression of vessel disease in some instances, but surgical reconstruction may be the only option in advanced stages, and even this is not always an option. An alternative and rather obvious strategy to treat ischemia is to activate endogenous angiogenic or vasculogenic pathways and stimulate revascularization of the tissue. The feasibility of such a strategy has now been established through the results of studies over the past decade and a new discipline called therapeutic angiogenesis has emerged. This review focuses on the application of therapeutic angiogenesis for treating peripheral limb ischemia and coronary artery diseases; the author traces the evidence supporting the feasibility of this treatment strategy, its current limitations, and possible directions.
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Affiliation(s)
- K A Webster
- Department of Molecular and Cellular Pharmacology, University of Miami Medical Center, FL 33136, USA
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16
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Abstract
Cardiac myocytes can undergo programmed cell death in response to a variety of insults and apoptotic elimination of myocytes from the adult myocardium can lead directly to cardiomyopathy and death. Although it remains to be shown that therapy specifically targeting apoptosis will improve the prognosis of ischemic heart disease or heart failure, a number of studies in the past year have shed light on potential ways to intervene in the process. Progress in the past year includes a better understanding of the importance of mitochondria-initiated events in cardiac myocyte apoptosis, of factors inducing apoptosis during hypoxia, and of the dual pro-apoptotic and anti-apoptotic effects of hypertrophic stimuli such as beta-adrenoceptor agonists, nitric oxide and calcineurin. Further evidence supports the pathophysiologic relevance of apoptosis in human heart disease. The tracking of cytoprotective and apoptotic signal transduction pathways has revealed important new insights into the roles of the mitogen-activated protein (MAP) kinases p38, extracellular signal regulated kinase (ERK) and c-Jun N-terminus kinase (JNK) in cardiac cell fate.
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Affiliation(s)
- N H Bishopric
- Department of Molecular and Cellular Pharmacology, University of Miami School of Medicine, Miami, Florida 33101, USA.
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17
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Yamashita K, Kajstura J, Discher DJ, Wasserlauf BJ, Bishopric NH, Anversa P, Webster KA. Reperfusion-activated Akt kinase prevents apoptosis in transgenic mouse hearts overexpressing insulin-like growth factor-1. Circ Res 2001; 88:609-14. [PMID: 11282895 DOI: 10.1161/01.res.88.6.609] [Citation(s) in RCA: 101] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Abstract -Hearts of wild-type and insulin-like growth factor-1 overexpressing (Igf-1(+/-)) transgenic mice were subjected to Langendorff perfusions and progressive periods of ischemia followed by reperfusion. Apoptosis was measured by DNA nucleosomal cleavage and a hairpin probe labeling assay to detect single-base overhang. Transgenic hearts subjected to 20 minutes of ischemia and 4 hours of reperfusion (I/R) sustained a rate of apoptosis of 1.8+/-0.3% compared with 4.6+/-1.1% for wild-type controls (n=4; P<0.03). Phosphorylation of the protein kinase Akt/protein kinase B was elevated 6.2-fold in transgenic hearts at baseline and increased another 4.4-fold within 10 minutes of reperfusion, remaining elevated for up to 2 hours. I/R activated Akt in wild-type hearts but to a lesser extent (1.6+/-0.3-fold). Pretreatment of transgenic hearts with wortmannin immediately before and during ischemia eliminated reperfusion-mediated activation of Akt and neutralized the resistance to apoptosis. The stress-activated kinase p38 was also activated during ischemia and reperfusion in both wild-type and transgenic hearts. Perfusion with the p38 inhibitor SB203580 (10 micromol/L) blocked both p38 activation and phosphorylation of Akt and differentially modulated apoptosis in wild-type and transgenic hearts. Pretreatment with SB203580 reduced apoptosis in wild-type hearts but increased apoptosis in transgenic hearts. These results demonstrate that Akt phosphorylation during I/R is modulated by IGF-1 and prevents apoptosis in hearts that overexpress the IGF-1 transgene.
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Affiliation(s)
- K Yamashita
- Department of Molecular and Cellular Pharmacology, University of Miami Medical Center, Miami, Florida, USA
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18
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Slepak TI, Webster KA, Zang J, Prentice H, O'Dowd A, Hicks MN, Bishopric NH. Control of cardiac-specific transcription by p300 through myocyte enhancer factor-2D. J Biol Chem 2001; 276:7575-85. [PMID: 11096067 DOI: 10.1074/jbc.m004625200] [Citation(s) in RCA: 66] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The transcriptional integrator p300 regulates gene expression by interaction with sequence-specific DNA-binding proteins and local remodeling of chromatin. p300 is required for cardiac-specific gene transcription, but the molecular basis of this requirement is unknown. Here we report that the MADS (MCM-1, agamous, deficiens, serum response factor) box transcription factor myocyte enhancer factor-2D (MEF-2D) acts as the principal conduit for cardiac transcriptional activation by p300. p300 activation of the native 2130-base pair human skeletal alpha-actin promoter required a single hybrid MEF-2/GATA-4 DNA motif centered at -1256 base pairs. Maximal expression of the promoter in cultured myocytes and in vivo correlated with binding of both MEF-2 and p300, but not GATA-4, to this AT-rich motif. p300 and MEF-2 were coprecipitated from cardiac nuclear extracts by an oligomer containing this element. p300 was found exclusively in a complex with MEF-2D at this and related sites in other cardiac-restricted promoters. MEF-2D, but not other MEFs, significantly potentiated cardiac-specific transcription by p300. No physical or functional interaction was observed between p300 and other factors implicated in skeletal actin transcription, including GATA-4, TEF-1, or SRF. These results show that, in the intact cell, p300 interactions with its protein targets are highly selective and that MEF-2D is the preferred channel for p300-mediated transcriptional control in the heart.
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Affiliation(s)
- T I Slepak
- Department of Molecular and Cellular Pharmacology, University of Miami, Florida 33101, USA
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19
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Abstract
Nitric oxide (NO) induces apoptosis in cardiac myocytes through an oxidant-sensitive mechanism. However, additional factors appear to modulate the exact timing and rate of NO-dependent apoptosis. In this study, we investigated the role of mitogen-activated protein kinases (MAPKs) (extracellular signal-regulated kinase [ERK] 1/2, c-Jun N-terminal kinase [JNK] 1/2, and p38MAPK) in NO-mediated apoptotic signaling. The NO donor S:-nitrosoglutathione (GSNO) induced caspase-dependent apoptosis in neonatal rat cardiac myocytes, preceded by a rapid (<10-minute) and significant (approximately 50-fold) activation of JNK1/2. Activation of JNK was cGMP dependent and was inversely related to NO concentration; it was maximal at the lowest dose of GSNO (10 micromol/L) and negligible at 1 mmol/L. NO slightly increased ERK1/2 beginning at 2 hours but did not affect p38MAPK activity. Inhibitors of ERK and p38MAPK activation did not affect cell death rates. In contrast, expression of dominant-negative JNK1 or MKK4 mutants significantly increased NO-induced apoptosis at 5 hours (56.77% and 57.37%, respectively, versus control, 40.5%), whereas MEKK1, an upstream activator of JNK, sharply reduced apoptosis in a JNK-dependent manner. Adenovirus-mediated expression of dominant-negative JNK1 both eliminated the rapid activation of JNK by NO and accelerated NO-mediated apoptosis by approximately 2 hours. These data indicate that NO activates JNK as part of a cytoprotective response, concurrent with initiation of apoptotic signaling. Early, transient activation of JNK serves both to delay and to reduce the total extent of apoptosis in cardiac myocytes.
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Affiliation(s)
- P Andreka
- Department of Molecular and Cellular Pharmacology, University of Miami, FL, USA
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20
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Webster KA, Discher DJ, Hernandez OM, Yamashita K, Bishopric NH. A glycolytic pathway to apoptosis of hypoxic cardiac myocytes. Molecular pathways of increased acid production. Adv Exp Med Biol 2000; 475:161-75. [PMID: 10849658 DOI: 10.1007/0-306-46825-5_16] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/16/2023]
Affiliation(s)
- K A Webster
- Department of Molecular and Cellular Pharmacology, University of Miami Medical Center, FL, USA
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21
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Abstract
Because of safety issues, components of the beta-adrenergic signaling pathway cannot currently be viewed as attractive targets for human gene therapy. Rather, the balance of evidence supports strategies that will target gene products specifically and directly at diastolic regulation. Augmenting the activity of the SR Ca2+ ATPase by AAV-mediated delivery of the SERCA2a gene, directed by a cardiac-specific promoter with a tightly regulable on-off switch is perhaps the most attractive strategy. PLB and cTnI also are attractive targets but only if molecular techniques can be devised to modulate their activity specifically and conditionally. Such techniques may involve modifying the phosphorylation sites in vitro and replacing wild type proteins in the failing heart with the modified forms, again using regulated AAV vectors for gene delivery.
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Affiliation(s)
- K A Webster
- Department of Molecular and Cellular Pharmacology, University of Miami Medical Center, Florida, USA.
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22
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Abstract
Elevated levels of oxygen free radicals have been implicated in the pathways of reperfusion injury to myocardial tissue. The targets for free radicals may include specific as well as random intracellular components, and part of the cellular response is the induction of extracellularly activated and stress-activated kinases. The intermediate signals that initiate these stress responses are not known. Here we show that one of the earliest responses of cardiac myocytes to hypoxia and reoxygenation is the activation of neutral sphingomyelinase and accumulation of ceramide. Ceramide increased abruptly after reoxygenation, peaking at 10 minutes with 225+/-40% of the control level. Neutral sphingomyelinase activity was induced with similar kinetics, and both activities remained elevated for several hours. c-Jun N-terminal kinase (JNK) was also activated within the same time frame. Treatment of cardiac myocytes with extracellular ceramides also activated JNK. Pretreating cells with antioxidants quenched sphingomyelinase activation, ceramide accumulation, and JNK activation. Ceramide did not accumulate in reoxygenated nonmuscle fibroblasts, and JNK was not activated by reoxygenation in these cells. The results identify neutral sphingomyelinase activation as one of the earliest responses of cardiac myocytes to the redox stress imposed by hypoxia-reoxygenation. The results are consistent with a pathway of ceramide-mediated activation of JNK.
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Affiliation(s)
- O M Hernandez
- Department of Molecular and Cellular Pharmacology, University of Miami Medical Center, FL 33136, USA
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23
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Cella D, Webster KA. Quality of life and treatment value in the management of hematologic malignancies. Semin Oncol 1999; 26:34-42. [PMID: 10561016] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/14/2023]
Abstract
This report is an overview of quality-of-life (QOL) concerns among people living with hematologic malignancies, and attempts to place these concerns in the context of overall therapeutic benefit and treatment value. There are two general categories of potential benefit offered by any treatment: time and QOL. If time can be added by a treatment, either by cure or prolonging survival, the value of that time makes toxicity more tolerable to patients, providers, payers, and society. If QOL can be improved, this will also make toxicity more acceptable. However, in the absence of time extension, this trade-off must demonstrate that the QOL benefit clearly outweighs the toxicity. In other words, the acceptability of toxicity increases as the likelihood of benefit improves. The range of possible symptoms and functional problems associated with hematologic malignancies is diverse, characterized by site and degree of involvement. Uncertainty of prognosis and the need to tolerate ambiguity frame many of the emotional challenges that face patients who must make difficult treatment and follow-up decisions. As more QOL data become available from clinical trials in hematologic malignancies, treatment decisions, while still difficult, can be made with more information about risk, type of improvements, toxicities, and probability of overall clinical benefit.
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Affiliation(s)
- D Cella
- Evanston Northwestern Healthcare and Robert H. Lurie Cancer Center, Northwestern University, Chicago, IL, USA
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24
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Abstract
1. Gene transfer into the myocardium can be achieved through direct injection of plasmid DNA or through the delivery of viral vectors, either directly or through the coronary vasculature. Direct DNA injection has proven extremely valuable in studies aimed at characterizing the activities of promoter elements in cardiac tissue and for examining the influence of the pathophysiological state of the myocardium on expression of transferred foreign genes. 2. Viral vectors, in particular adenoviruses and adeno-associated virus, are capable of transfecting genetic material with high transduction efficiencies and have been applied to a range of model systems for in vivo gene transfer. Efficient gene transfer has been achieved into the coronary vessels and surrounding myocardium by intracoronary infusion of adenovirus. 3. Because the immunogenicity of viral vectors can limit transgene expression, much attention has been paid to strategies for circumventing this, including the development of new modified adenovirus and adeno-associated virus vectors that do not elicit significant inflammatory responses. While cellular transplantation may prove valuable for the repair of myocardial tissue, confirmation of its value awaits establishment of a functional improvement in the myocardium following cell grafting. 4. Because gene transfer into the myocardium can now be achieved with high efficiency in the absence of significant inflammatory responses, the ability to regulate foreign gene expression in response to an endogenous disease phenotype will enable the development of new effective viral vectors with direct clinical applicability for specified therapeutic targets.
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Affiliation(s)
- M Y Alexander
- Division of Molecular Genetics, Institute of Biomedical and Life Sciences, University of Glasgow, UK
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25
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Webster KA, Discher DJ, Kaiser S, Hernandez O, Sato B, Bishopric NH. Hypoxia-activated apoptosis of cardiac myocytes requires reoxygenation or a pH shift and is independent of p53. J Clin Invest 1999; 104:239-52. [PMID: 10430605 PMCID: PMC408414 DOI: 10.1172/jci5871] [Citation(s) in RCA: 185] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/1998] [Accepted: 06/24/1999] [Indexed: 02/02/2023] Open
Abstract
Ischemia and reperfusion activate cardiac myocyte apoptosis, which may be an important feature in the progression of ischemic heart disease. The relative contributions of ischemia and reperfusion to apoptotic signal transduction have not been established. We report here that severe chronic hypoxia alone does not cause apoptosis of cardiac myocytes in culture. When rapidly contracting cardiac myocytes were exposed to chronic hypoxia, apoptosis occurred only when there was a decrease in extracellular pH ([pH](o)). Apoptosis did not occur when [pH](o) was neutralized. Addition of acidic medium from hypoxic cultures or exogenous lactic acid stimulated apoptosis in aerobic myocytes. Hypoxia-acidosis-mediated cell death was independent of p53: equivalent apoptosis occurred in cardiac myocytes isolated from wild-type and p53 knockout mice, and hypoxia caused no detectable change in p53 abundance or p53-dependent transcription. Reoxygenation of hypoxic cardiac myocytes induced apoptosis in 25-30% of the cells and was also independent of p53 by the same criteria. Finally, equivalent levels of apoptosis, as demonstrated by DNA fragmentation, were induced by ischemia-reperfusion, but not by ischemia alone, of Langendorff-perfused hearts from wild-type and p53 knockout mice. We conclude that acidosis, reoxygenation, and reperfusion, but not hypoxia (or ischemia) alone, are strong stimuli for programmed cell death that is substantially independent of p53.
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Affiliation(s)
- K A Webster
- Department of Molecular and Cellular Pharmacology, University of Miami Medical Center, Florida 33136, USA.
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26
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Discher DJ, Bishopric NH, Hernandez OM, Webster KA. Instability of a multiple copy enhancer in plasmid vectors: practical considerations. Biotechniques 1999; 26:1026-8, 1030. [PMID: 10376132 DOI: 10.2144/99266bm03] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022] Open
Affiliation(s)
- D J Discher
- University of Miami, Department of Molecular and Cellular Pharmacology, FL 33101, USA
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27
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Abstract
Oestrosis is a parasitic disease of sheep and goats caused by the nasal bot fly Oestrus ovis. In the United Kingdom the economic losses as a result of infestation can be considered negligible, but the differentiation of O ovis cases from more serious diseases such as listeriosis, gid and sheep scab is of considerable importance. Currently, diagnosis of oestrosis relies on the subjective observation of clinical signs or the demonstration of larvae postmortem. This paper assesses the effectiveness of a direct enzyme-linked immunosorbent assay (ELISA) using a crude somatic antigen from first-stage larvae (L1) in the serodiagnosis of oestrosis. The system has been validated with sera from both endemic and non-endemic areas and the results correlated with the clinical data found postmortem. The sensitivity and specificity of the assay were 97.4 per cent and 97.6 per cent, respectively, using a cut-off point based on 35 per cent binding of a reference positive control serum.
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Affiliation(s)
- P Goddard
- Veterinary Laboratories Agency, Addlestone, Surrey
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28
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Murphy BJ, Andrews GK, Bittel D, Discher DJ, McCue J, Green CJ, Yanovsky M, Giaccia A, Sutherland RM, Laderoute KR, Webster KA. Activation of metallothionein gene expression by hypoxia involves metal response elements and metal transcription factor-1. Cancer Res 1999; 59:1315-22. [PMID: 10096565] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/11/2023]
Abstract
Metallothioneins (MTs) are a family of stress-induced proteins with diverse physiological functions, including protection against metal toxicity and oxidants. They may also contribute to the regulation of cellular proliferation, apoptosis, and malignant progression. We reported previously that the human (h)MT-IIA isoform is induced in carcinoma cells (A431, SiHa, and HT29) exposed to low oxygen, conditions commonly found in solid tumors. The present study demonstrates that the genes for hMT-IIA and mouse (m)MT-I are transcriptionally activated by hypoxia through metal response elements (MREs) in their proximal promoter regions. These elements bind metal transcription factor-1 (MTF-1). Deletion and mutational analyses of the hMT-IIA promoter indicated that the hMRE-a element is essential for basal promoter activity and for induction by hypoxia, but that other elements contribute to the full transcriptional response. Functional studies of the mMT-I promoter demonstrated that at least two other MREs (mMRE-d and mMRE-c) are responsive to hypoxia. Multiple copies of either hMRE-a or mMRE-d conferred hypoxia responsiveness to a minimal MT promoter. Mouse MT-I gene transcripts in fibroblasts with targeted deletions of both MTF-1 alleles (MTF-1(-/-); dko7 cells) were not induced by zinc and showed low responsiveness to hypoxia. A transiently transfected MT promoter was unresponsive to hypoxia or zinc in dko7 cells, but inductions were restored by cotransfecting a mouse MTF-1 expression vector. Electrophoretic mobility shift assays detected a specific protein-DNA complex containing MTF-1 in nuclear extracts from hypoxic cells. Together, these results demonstrate that hypoxia activates MT gene expression through MREs and that this activation involves MTF-1.
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Affiliation(s)
- B J Murphy
- Pharmaceutical Discovery Division, SRI International, Menlo Park, California 94025, USA.
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29
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Abstract
-Cytokine-induced NO production depresses myocardial contractility and has been shown to be cytotoxic to cardiac myocytes. However, the mechanisms of cytokine-induced cardiac myocyte cell death are unclear. To analyze these mechanisms in detail, we treated neonatal cardiac myocytes in serum-free culture with a combination of the macrophage-derived cytokines interleukin-1beta, tumor necrosis factor-alpha, and interferon-gamma. These cytokines caused a time-dependent induction of cardiac myocyte apoptosis, but not necrosis, beginning 72 hours after treatment, as determined by nuclear morphology, DNA internucleosomal cleavage, and cleavage of poly(ADP-ribose) polymerase, reflecting caspase activation. Apoptosis was preceded by a >50-fold induction of inducible NO synthase mRNA and the release of large amounts (5 to 8 nmol/ microgram protein) of NO metabolites (NOx) into the medium. Cell death was completely blocked by an NO synthase inhibitor and attenuated by antioxidants (N-acetylcysteine and DTT) and the caspase inhibitor ZVAD-fmk. Cytokines also mediated an NO-dependent, sustained increase in myocyte expression of the Bcl-2 homologs Bak and Bcl-x(L). The NO donor S-nitrosoglutathione also induced apoptosis and cell levels of Bak, but not of Bcl-x(L). All effects of cytokines, including poly(ADP-ribose) polymerase cleavage, could be attributed to interleukin-1beta; interferon-gamma and tumor necrosis factor-alpha had no independent effects on apoptosis or on NOx production. We conclude that cytokine toxicity to neonatal cardiac myocytes results from the induction of NO and subsequent activation of apoptosis, at least in part through the generation of oxygen free radicals. The rate and extent of this apoptosis is modulated by alterations in the cellular balance of Bak and Bcl-x(L), which respond differentially to cytokine-induced and exogenous NO and by the availability of oxidant species.
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Affiliation(s)
- D J Ing
- Departments of Molecular and Cellular Pharmacology and Medicine, University of Miami School of Medicine, Miami, Florida, USA. Medicine
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30
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Taylor MA, Webster KA. Recent advances in the diagnosis in livestock of Cryptosporidium, Toxoplasma, Giardia and other protozoa of veterinary importance. Res Vet Sci 1998; 65:183-93. [PMID: 9915141 PMCID: PMC7131700 DOI: 10.1016/s0034-5288(98)90141-2] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [MESH Headings] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 05/21/1998] [Indexed: 01/23/2023]
Affiliation(s)
- M A Taylor
- Parasitology Discipline, Central Veterinary Laboratory, (Veterinary Laboratories Agency), New Haw, Addlestone, Surrey
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31
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Discher DJ, Bishopric NH, Wu X, Peterson CA, Webster KA. Hypoxia regulates beta-enolase and pyruvate kinase-M promoters by modulating Sp1/Sp3 binding to a conserved GC element. J Biol Chem 1998; 273:26087-93. [PMID: 9748288 DOI: 10.1074/jbc.273.40.26087] [Citation(s) in RCA: 138] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023] Open
Abstract
The transcription rates of glycolytic enzyme genes are coordinately induced when cells are exposed to low oxygen tension. This effect has been described in many cell types and is not restricted to species or phyla. In mammalian cells, there are 11 distinct glycolytic enzymes, at least 9 of which are induced by hypoxia. Recent reports described a role for the hypoxia-inducible factor-1 (HIF-1) in the transcriptional activation of lactate dehydrogenase A, aldolase-A, phosphoglycerate kinase, and enolase-1 genes. It is not known whether the HIF-1 factor acts exclusively to regulate these genes during hypoxia, or how the other genes of the pathway are regulated. In this paper, we describe analyses of the muscle-specific pyruvate kinase-M and beta-enolase promoters that implicate additional mechanisms for the regulation of glycolytic enzyme gene transcription by hypoxia. Transient transcription of a reporter gene directed by either promoter was activated when transfected muscle cells were exposed to hypoxia. Neither of these promoters contain HIF-1 binding sites. Instead, the hypoxia response was localized to a conserved GC-rich element positioned immediately upstream of a GATAA site in the proximal promoter regions of both genes. The GC element was essential for both basal and hypoxia-induced expression and bound the transcription factors Sp1 and Sp3. Hypoxia caused the progressive depletion of Sp3 determined by DNA binding studies and Western analyses, whereas Sp1 protein levels remained unchanged. Overexpression of Sp3 repressed expression of beta-enolase promoters. It is concluded that hypoxia activates these glycolytic enzyme gene promoters by down-regulating Sp3, thereby removing the associated transcriptional repression.
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Affiliation(s)
- D J Discher
- Department of Molecular and Cellular Pharmacology, University of Miami Medical Center, Miami, Florida 33136, USA
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32
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Affiliation(s)
- R N Marshall
- Central Veterinary Laboratory, Veterinary Laboratories Agency, Addlestone, Surrey
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33
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Webster KA, Dawson C, Gillard K. Warble fly status of Great Britain in 1997. Vet Rec 1998; 142:549. [PMID: 9637383] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Affiliation(s)
- K A Webster
- Veterinary Laboratories Agency, New Haw, Addlestone, Surrey
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34
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Hu J, Discher DJ, Bishopric NH, Webster KA. Hypoxia regulates expression of the endothelin-1 gene through a proximal hypoxia-inducible factor-1 binding site on the antisense strand. Biochem Biophys Res Commun 1998; 245:894-9. [PMID: 9588211 DOI: 10.1006/bbrc.1998.8543] [Citation(s) in RCA: 213] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
Endothelin-1 (ET-1) is a peptide hormone with potent vasoconstrictor properties that is synthesized and secreted predominantly by vascular endothelial cells. Its production is regulated by numerous stimuli including ischemia and hypoxia, and the enhanced levels that occur during myocardial ischemia may contribute to the progression of heart failure. We previously reported that ET-1 expression was induced by both hypoxia and transition metals in endothelial cells (ECs). Here we define an element in the proximal promoter of the ET-1 gene that is responsible for this induction. By using deletions and site directed mutagenesis of the human ET-1 promoter, in combination with electrophoretic gel mobility shifts and transient expression assays in human ECs, we identified an active hypoxia-inducible factor 1 (HIF-1) binding site starting at position -118 upstream of the transcription start site on the non-coding DNA strand. Mutation of this site eliminated induction by hypoxia without affecting basal (aerobic) expression, and the mutated sequence did not display hypoxia-specific binding of HIF-1.
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Affiliation(s)
- J Hu
- Department of Molecular and Cellular Pharmacology, University of Miami Medical Center, Florida 33136, USA
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35
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Affiliation(s)
- H Prentice
- Department of Genetics, University of Glasgow, UK
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36
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Abstract
Incorporation of quality of life (QOL) investigation into Eastern Cooperative Oncology Group (ECOG) multi-centre clinical trials has led to innovative strategies for protocol design and high quality data collection. A scientific advisory committee reviews protocol design components, measurement selection, timing of assessments and compliance issues. Extensive educational programmes provide information about the scientific and clinical relevance of QOL protocols, as well as practical strategies for data collection and management. Compliance with QOL data collection standards is prospectively monitored and evaluated. Preliminary results from eight ECOG-run protocols found overall compliance to be approximately 85 per cent (94 per cent at baseline and 73 per cent during treatment). Selected patient and institutional factors were evaluated for their association with compliance.
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Affiliation(s)
- E A Hahn
- Center on Outcomes, Research and Education, Evanston Northwestern Healthcare, IL 60201, USA.
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37
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Webster KA, Dawson C, Flowers M, Richards MS. Serological prevalence of Hypoderma species in cattle in Great Britain (1995/96) and the relative value of serological surveillance over clinical observation. Vet Rec 1997; 141:261-3. [PMID: 9316238 DOI: 10.1136/vr.141.11.261] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
Sera from 100,400 cattle on 2850 farms in England, Scotland and Wales were tested for the presence of antibodies to Hypoderma species between the end of November 1995 and the end of February 1996. Twelve animals were resampled because the initial results were equivocal but only one of them was confirmed as seropositive. This animal was a bull imported from Belgium which had been treated with an approved warble fly treatment within 24 hours of arrival at its destination in Great Britain. No seropositive animals were confirmed within the native British cattle population. Statistical analysis of these data indicates that the probable maximum number of infested cattle herds in Great Britain is 112. To detect the disease by direct clinical observation would require more than 500 herds to be infested, indicating that the serological testing of this number of cattle and farms is more than four times as sensitive as clinical observation for the detection of hypodermosis.
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Affiliation(s)
- K A Webster
- Veterinary Laboratories Agency, Addlestone, Surrey
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38
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Abstract
OBJECTIVES Regulated expression of transferred foreign genes may be an important feature of gene therapy. Because coronary artery disease often involves intermittent myocardial ischaemia followed by periods of normal cardiac function it will probably be necessary to regulate the expression of putative therapeutic/cardioprotective genes directly in response to ischaemia-associated signals. The objectives of the current study were to develop a combination of gene regulatory components that can be used to target a product to the myocardium and limit the expression of the gene to periods of ischaemic activity. METHODS Expression plasmids were constructed containing muscle-specific promoters and hypoxia-responsive enhancer elements linked to a reporter gene. The regulation of these constructs by hypoxia or experimental ischaemia was measured following transient expression in cultured cells or after direct injection of DNA into the rabbit myocardium. RESULTS A single set of hypoxia response elements placed immediately upstream of the minimal muscle-specific alpha-myosin heavy chain promoter conferred potent positive regulation of this promoter by hypoxia in vitro and by ischaemia in vivo. Induction by ischaemia persisted for at least 4 h and returned to the baseline level within 8 h. CONCLUSIONS Hypoxia responsive regulatory elements, in combination with weak tissue-restricted promoters incorporated into an appropriate vector system may allow controlled expression of a therapeutic gene in ischaemic myocardium.
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Affiliation(s)
- H Prentice
- Pharmaceutical Discovery Division, SRI International, Menlo Park, CA, USA
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39
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Abstract
Adenovirus E1A oncoproteins inhibit muscle-specific gene expression and myogenic differentiation by suppressing the transcriptional activating functions of basic helix-loop-helix proteins. As one approach to identifying cardiac-specific gene regulatory proteins, we analyzed the functional regions of E1A proteins that are required for muscle gene repression in cardiac cells. Myocyte-specific promoters, including the alpha-actins and alpha-myosin heavy chain, were selectively and potently inhibited (>90%) by E1A, while the ubiquitously expressed beta-actin promoter was only partially ( approximately 30%) repressed; endogenous gene expression was also affected. Distinct E1A protein binding sites mediated repression of muscle-specific and ubiquitous actin promoters. E1A-mediated inhibition of beta-actin required both an intact binding site for the tumor repressor proteins pRb and p107 and a second E1A domain (residues 15-35). In contrast, cardiac-specific promoter repression required the E1A amino-terminal residues 2-36. The proximal skeletal actin promoter (3' to base pair -153) was a target for repression by E1A. Although E1A binding to p300 was not required for inhibition of either promoter, co-expression of p300 partially reversed E1A-mediated transcriptional repression. We conclude that cardiac-specific and general promoter inhibition by E1A occurs by distinct mechanisms and that cardiac-specific gene expression is modulated by cellular factors interacting with the E1A p300/CBP-binding domain.
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Affiliation(s)
- N H Bishopric
- Molecular Cardiology Laboratory, SRI International, Menlo Park, California 94125, USA
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40
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Taylor A, Webster KA, Gustafson TA, Kedes L. The anti-cancer agent distamycin A displaces essential transcription factors and selectively inhibits myogenic differentiation. Mol Cell Biochem 1997; 169:61-72. [PMID: 9089632 DOI: 10.1023/a:1006898812618] [Citation(s) in RCA: 25] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
The anticancer drug, distamycin A, alters DNA conformation by binding to A/T-rich domains. We propose that binding of the drug to DNA alters transcription factor interactions and that this may alter genetic regulation. We have analyzed the effects of distamycin A upon expression of the muscle-specific cardiac and skeletal alpha-actin genes which have A/T-rich regulatory elements in their promoters. Distamycin A specifically inhibited endogenous muscle genes in the myogenic C2 cell line and effectively eliminated the myogenic program. Conversely, when 10T1/2C18 derived pleuripotential TA1 cells were induced to differentiate in the presence of distamycin A, adipocyte differentiation was enhanced whereas the numbers of cells committing to the myogenic program decreased dramatically. Using the mobility shift assay distamycin A selectively inhibited binding of two important transcription factors, SRF and MEF2, to their respective A/T-rich elements. The binding of factors Sp1 and MyoD were not affected. The inhibition of factor binding correlated with a repression of muscle-specific promoter activity as assayed by transient transfection assays. Co-expression of the myoD gene, driven by a distamycin A-insensitive promoter, failed to relieve the inhibition of these muscle-specific promoters by distamycin A. Additionally, SRF and MEF2 dependent promoters were selectively down regulated by distamycin A. These results suggest that distamycin A may inhibit muscle-specific gene expression by selectively interfering with transcription factor interactions and demonstrate the importance of these A/T-rich elements in regulating differentiation of this specific cell type.
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Affiliation(s)
- A Taylor
- Department of Biological Sciences, Wichita State University, KS 67208, USA
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41
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Abstract
Hypoxia and reoxygenation are principal components of myocardial ischemia and reperfusion and have distinctive effects on the tissue. Both conditions have been associated with inflammation, necrosis, apoptosis, and myocardial infarction. Using a cell culture model of ischemia and reperfusion in which cardiac myocytes were exposed to cycles of hypoxia and reoxygenation, we report here that reoxygenation, but not hypoxia alone, caused sustained approximately 10-fold increases in phosphorylation of the amino-terminal domain of the c-jun transcription factor. The activation was similar to treatments with anisomycin or okadaic acid and correlated with the hypoxia-mediated depression of intracellular glutathione. Reoxygenation-induced c-Jun kinase activity was reduced by preincubating myocytes during the hypoxia phase with the spin-trap agent alpha-phenyl N-tert-butylnitrone or with N-acetylcysteine. The kinase activation was also inhibited by the tyrosine kinase inhibitor genistein but not by other protein kinase inhibitors. These results implicate unquenched reactive oxygen intermediates as the stimulus that initiates a kinase pathway involving the stress-activated protein kinases (JNKs/SAPKs) in reoxygenated cardiac myocytes.
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Affiliation(s)
- K R Laderoute
- Department of Cell and Molecular Biology, SRI International, Menlo Park, Calif, USA
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42
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Abstract
Hypodermosis is a parasitic disease of cattle caused by Hypoderma lineatum and H. bovis. It is an important health and welfare problem of infested cattle and a cause of considerable economic loss. In live animals, detection can be either by direct clinical examination of infested cattle and palpation of second and third stage larvae in the back or by the use of serological methods. This paper describes a competitive ELISA for the detection of antibodies to Hypoderma species in cattle sera. It has been validated using a small panel of 40 samples from clinically positive cattle and 200 samples from clinically negative (unexposed) cattle from a warble free area. Sensitivity and specificity calculated from this panel were 100% and 92% respectively at 2 SD from the mean or 92.5% and 98.5% at 3 SD from the mean. The use of serology and direct clinical examination of affected cattle, are discussed as methods for monitoring hypodermosis. The competitive ELISA should prove a useful adjunct to the standard sandwich ELISA, particularly in the resolution of samples which display non-specific binding properties.
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Affiliation(s)
- K A Webster
- Central Veterinary Laboratory, New Haw, Addlestone, Surrey, UK.
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43
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Cella DF, Dineen K, Arnason B, Reder A, Webster KA, karabatsos G, Chang C, Lloyd S, Steward J, Stefoski D. Validation of the functional assessment of multiple sclerosis quality of life instrument. Neurology 1996; 47:129-39. [PMID: 8710066 DOI: 10.1212/wnl.47.1.129] [Citation(s) in RCA: 257] [Impact Index Per Article: 9.2] [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: 02/01/2023] Open
Abstract
Based on scientific literature and interviews with clinicians and patients, we developed a quality of life instrument for use with people with MS called the Functional Assessment of Multiple Sclerosis (FAMS). The initial item pool consisted of 88 questions: 28 from the general version of the Functional Assessment of Cancer Therapy quality of life instrument, plus 60 generated by patients, providers, and literature review. The validation samples comprised a mail survey cohort (N = 377) and a clinical cohort (N = 56). Both cohorts provides evidence for internal consistency of the derived subscales, test-retest reliability, content validity, concurrent validity, and construct validity. Principal components and Rasch measurement model analyses were applied sequentially to survey sample data, reducing test length to 44 questions, divided into six subscales: mobility, symptoms, emotional well-being (depression), general contentment, thinking/fatigue, and family/social well-being. Fifteen initially rejected questions were added back as miscellaneous (unscored) questions for their potential clinical and empirical value. The mobility subscale was strongly predictive of the Kurtzke Extended Disability Status Scale and the Scripps Neurologic Rating Scales. The other five subscales were not, indicating they measure aspects of patient quality of life not captured by the neurologic exam. The final 59-item English language instrument (FAMS version 2) is available for inclusion in clinical trials and clinical practice.
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Affiliation(s)
- D F Cella
- Rush-Presbyterian-St. Luke's Medical Center, Chicago, IL, USA
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44
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Abstract
Current methods of gene transfer into cultured cardiac myocytes have serious limitations, including low efficiency, toxicity or constraints on DNA insert size. The present study examined the effectiveness of hemagglutinating virus of Japan (HVJ) in promoting liposome-mediated DNA transfer into cultured neonatal rat cardiac myocytes. Fluorescein isothiocyanate-labeled oligonucleotides (F-ODN) or plasmid expression vectors encoding SV40 large T antigen (pActSVT) and beta-galactosidase (pAct beta-gal) were complexed with liposomes and the viral protein coat of HVJ. Plasmid vectors were complexed with the nuclear localizing protein HMG-1 prior to HVJ-liposome encapsulation. Neonatal myocytes were transfected by incubation with HVJ-liposome/DNA complexes on culture day 3 or 7. Using F-ODN, we were able to demonstrate significant uptake of DNA (transfection efficiencies of 80-90%) 1 h after transfection that persisted for 1 week in culture. Interestingly, F-ODN were concentrated in the myocyte nuclei for the first 4 days after transfection. Immunohistochemistry showed that 25-30% of myocytes transfected with either pActSVT or pAct beta-Gal expressed plasmid-encoded protein at 72 h whether they were transfected at day 3 or day 7 of culture, while cells transfected with blank vectors did not. Quantitative beta-galactosidase assays confirmed that the use of HVJ significantly enhanced liposome-mediated transfection. Cell toxicity was not apparent. Gene transfer via intracoronary injection also demonstrated the capacity of HVJ to mediate transfection of rabbit cardiac myocytes in vivo, with F-ODN-dependent fluorescence persisting for up to 1 week. We conclude that HVJ/liposome-mediated transfer is efficient for the transfection of both oligonucleotides and plasmids into cardiac myocytes both in vitro and in vivo, and may provide a new tool for the investigation of cardiac myocyte biology and disease.
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Affiliation(s)
- K E Ellison
- Falk Cardiovascular Research Center, Stanford, CA, USA
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45
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Wu X, Bishopric NH, Discher DJ, Murphy BJ, Webster KA. Physical and functional sensitivity of zinc finger transcription factors to redox change. Mol Cell Biol 1996; 16:1035-46. [PMID: 8622648 PMCID: PMC231086 DOI: 10.1128/mcb.16.3.1035] [Citation(s) in RCA: 159] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023] Open
Abstract
Redox regulation of DNA-binding proteins through the reversible oxidation of key cysteine sulfhydryl groups has been demonstrated to occur in vitro for a range of transcription factors. The direct redox regulation of DNA binding has not been described in vivo, possibly because most protein thiol groups are strongly buffered against oxidation by the highly reduced intracellular environment mediated by glutathione, thioredoxin, and associated pathways. For this reason, only accessible protein thiol groups with high thiol-disulfide oxidation potentials are likely to be responsive to intracellular redox changes. In this article, we demonstrate that zinc finger DNA-binding proteins, in particular members of the Sp-1 family, appear to contain such redox-sensitive -SH groups. These proteins displayed a higher sensitivity to redox regulation than other redox-responsive factors both in vitro and in vivo. This effect was reflected in the hyperoxidative repression of transcription from promoters with essential Sp-1 binding sites, including the simian virus 40 early region, glycolytic enzyme, and dihydrofolate reductase genes. Promoter analyses implicated the Sp-1 sites in this repression. Non-Sp-1-dependent redox-regulated genes including metallothionein and heme oxygenase were induced by the same hyperoxic stress. The studies demonstrate that cellular redox changes can directly regulate gene expression in vivo by determining the level of occupancy of strategically positioned GC-binding sites.
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Affiliation(s)
- X Wu
- Department of Cell and Molecular Biology, SRI International, Menlo Park, California 94025 USA
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46
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Webster KA, Smith HV, Giles M, Dawson L, Robertson LJ. Detection of Cryptosporidium parvum oocysts in faeces: comparison of conventional coproscopical methods and the polymerase chain reaction. Vet Parasitol 1996; 61:5-13. [PMID: 8750678 DOI: 10.1016/0304-4017(95)00811-x] [Citation(s) in RCA: 73] [Impact Index Per Article: 2.6] [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: 02/02/2023]
Abstract
Conventional and coproscopical methods were compared with the polymerase chain reaction (PCR) for the detection of Cryptosporidium oocysts in bovine faeces. Oocysts were not detected in samples seeded with 10,000 oocysts following formol ether sedimentation and examination using auramine phenol (AP) or by immunofluorescent (IF) staining. When oocysts were concentrated using sucrose flotation the threshold of detection was 4000 oocysts per gram for both staining methods. Following salt flotation 4000 oocysts per gram could be reliably detected by AP staining but the detection limit was increased to 6000 oocysts per gram using IF staining. The recovery of oocysts was significantly less than expected for all techniques. A specific PCR coupled with immunomagnetic particle separation (IMS) of samples detected five oocysts per ml of diluted faeces, which corresponds to 80-90 oocysts per gram. Even allowing for the dilution of formed faecal samples, required for IMS, this represents an increase in sensitivity of several orders of magnitude over the conventional corpodiagnostic methods.
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Affiliation(s)
- K A Webster
- Central Veterinary Laboratory, New Haw, Addlestone, UK
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47
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Abstract
OBJECTIVES Endothelin-1 (ET-1) is a potent vasoconstrictor that is expressed in endothelial cells and in many other cells and tissues. Increased plasma levels of the peptide have been associated with ischemic heart disease, atherosclerosis, and myocardial infarction. The objectives of the current study were (1) to determine the tissue specificity for induction of the ET-1 gene by hypoxia, (2) to determine whether the hypoxia regulatory pathway is the same as that in other hypoxia regulated genes and (3) to analyze the contributions of protein kinases for basal and induced expression of ET-1. METHODS ET-1 transcript levels were measured by Northern blot and quantitative polymerase chain reaction in endothelial and non-endothelial cells following exposure to hypoxia. Regulatory steps within the pathway were identified by treating aerobic or hypoxic cultures with cycloheximide, PMA, a series of selective protein kinase inhibitors, and transition metals. The effects on ET-1 transcripts were compared with the ubiquitous hypoxia inducible pyruvate kinase gene. RESULTS The induction of ET-1 by hypoxia in vitro occurred exclusively in early passage endothelial cells. This induction was prevented by treatment with the protein synthesis inhibitor cycloheximide and was at least partially mimicked by treatment with transition metals. Induction by hypoxia was not effected by inhibitors of protein kinase C, protein kinase A, calcium-calmodulin dependent protein kinase, or cyclic GMP dependent protein kinase. The basal expression was decreased and hypoxic induction was eliminated by treating cells with tyrosine kinase-selective inhibitors. CONCLUSIONS Et-1 induction by hypoxia requires endothelial cell-specific factor(s) or steps, new protein synthesis, and may involve a haeme protein-containing pathway in oxygen sensing. A protein tyrosine kinase step is implicated for both basal and induced expression of the ET-1 gene.
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Affiliation(s)
- I Bodi
- Department of Cell and Molecular Biology, SRI International, Menlo Park, CA 94025, USA
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48
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Leskawa KC, Maddox T, Webster KA. Effects of ethanol on neuroblastoma cells in culture: role of gangliosides in neuritogenesis and substrate adhesion. J Neurosci Res 1995; 42:377-84. [PMID: 8583506 DOI: 10.1002/jnr.490420312] [Citation(s) in RCA: 7] [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
Murine Neuro-2A neuroblastoma cells were exposed to ethanol in culture under two experimental paradigms: (1) short-term (24 hr or less) and low concentrations (0.05 to 0.5%; 8.5 to 86 mM) and (2) long-term (48 hr at 0.5%; 86 mM). Long-term ethanol exposure did not affect Neuro-2A viability, determined by DNA synthesis or the ability to exclude Trypan Blue. Similarly, long-term ethanol treatment did not inhibit differentiation, exhibited by the extension of neurites, promoted by either dibutyryl-cyclic-AMP or by incubation with exogenous ganglioside GM1. The incorporation of exogenous ganglioside GM1 into plasma membranes was not influenced by varying concentrations of ethanol (up to 1.2%; 204 mM). In contrast, ethanol did influence Neuro-2A cell attachment to collagen in a dualistic manner. During short-term ethanol exposure, cell attachment was enhanced. However, when cells were initially exposed to ethanol for 48 hr a marked inhibition of subsequent attachment was observed. Long-term ethanol exposure also inhibited attachment to other substrata, including laminin, fibronectin and vitronectin. Incubation of Neuro-2A cells with either exogenous ganglioside GM1 or a mixture of brain gangliosides partially reversed the inhibition of attachment to collagen. This reversal did not appear to be due to any one particular ganglioside structure, however. Mixed brain gangliosides were fractionated into three fractions, according to the number of sialic acid residues. Each of the three fractions were equally effective in partially restoring Neuro-2A cell attachment to collagen after long-term ethanol treatment. The results suggest that the mechanism by which these effects occur is at the level of plasma membrane fluidity, because both ethanol and glycosphingolipid content are known to influence membrane lateral mobility, although other mechanisms, such as changes in headgroup hydration, are possible.
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Affiliation(s)
- K C Leskawa
- Department of Anatomical Sciences and Neurobiology, School of Medicine, University of Louisville, Kentucky 40292, USA
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49
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Abstract
Short periods of myocardial ischemia appear to provide protection against subsequent prolonged ischemic episodes in experimental animals and in man. This phenomenon, known as ischemic preconditioning, has not yet been characterized at the cellular or molecular levels; however, tissue hypoxia appears to be required. In this study, we used a previously developed method for hypoxic cardiac myocyte culture in order to establish a model for ischemic (or hypoxic) preconditioning in cell culture. We demonstrate that cultured neonatal rat cardiac myocytes preconditioned by 25 min of exposure to hypoxia followed by reoxygenation were protected against membrane damage for up to 6 h of prolonged severe hypoxia, as determined by arachidonic acid release and contractile recovery. In contrast, non-preconditioned myocytes exhibited significant hypoxic damage after 2-4 h. Pretreatment of cells with PMA, a tumor-promoting phorbol ester, mimicked the protective effects of hypoxic preconditioning; pretreatment with the muscarinic cholinergic agonist carbachol had no effect. Our data suggests that isolated myocytes in culture remain competent to be preconditioned by hypoxia, through a pathway that may involve the activation of protein kinase C.
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Affiliation(s)
- K A Webster
- Program in Molecular Cardiology, SRI International, Menlo Park, CA 94025, USA
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50
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Abstract
We have previously demonstrated coordinate inductions of c-fos, c-jun, jun B, and jun D in cardiac myocytes exposed to hypoxia for 2 to 4 hours. Induction of these transcripts occurred before any significant loss of intracellular ATP. In the present study, the origin of the signal(s) that regulates immediate-early gene induction was investigated by comparing the effects of hypoxia with those of the metabolic inhibitors cyanide, deoxyglucose and cyanide combined, and iodoacetic acid. Cyanide, an inhibitor of oxidative metabolism, closely mimicked the metabolic effects of hypoxia, with elimination of oxygen consumption, increased lactate production, and minimal decline in ATP levels under both conditions. Compared with hypoxia, cyanide mediated small transient inductions of fos and jun transcripts that followed a different time course. The combination of cyanide and deoxyglucose resulted in inhibition of lactate production as well as respiration, and ATP dropped rapidly to 20% of control levels. The loss of intracellular ATP was followed by fourfold inductions of c-fos and c-jun with minor changes in jun B and jun D transcript levels. Similarly, iodoacetic acid caused a major (90%) loss of ATP and irreversible cell damage as measured by leakage of creatine phosphokinase enzyme and loss of membrane arachidonic acid; ATP loss was followed by fivefold to sevenfold inductions of c-fos, c-jun and jun B transcripts.(ABSTRACT TRUNCATED AT 250 WORDS)
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Affiliation(s)
- K A Webster
- Department of Cell and Molecular Biology, SRI International, Menlo Park, CA 94025
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