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Ponjoan A, Garre-Olmo J, Blanch J, Fages E, Alves-Cabratosa L, Martí-Lluch R, Comas-Cufí M, Parramon D, Garcia-Gil M, Ramos R. Is it time to use real-world data from primary care in Alzheimer's disease? Alzheimers Res Ther 2020; 12:60. [PMID: 32423489 PMCID: PMC7236302 DOI: 10.1186/s13195-020-00625-2] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2019] [Accepted: 05/01/2020] [Indexed: 12/17/2022]
Abstract
BACKGROUND The analysis of real-world data in clinical research is rising, but its use to study dementia subtypes has been hardly addressed. We hypothesized that real-world data might be a powerful tool to update AD epidemiology at a lower cost than face-to-face studies, to estimate the prevalence and incidence rates of AD in Catalonia (Southern Europe), and to assess the adequacy of real-world data routinely collected in primary care settings for epidemiological research on AD. METHODS We obtained data from the System for the Development of Research in Primary Care (SIDIAP) database, which contains anonymized information of > 80% of the Catalan population. We estimated crude and standardized incidence rates and prevalences (95% confidence intervals (CI)) of AD in people aged at least 65 years living in Catalonia in 2016. RESULTS Age- and sex-standardized prevalence and incidence rate of AD were 3.1% (95%CI 2.7-3.6) and 4.2 per 1000 person-years (95%CI 3.8-4.6), respectively. Prevalence and incidence were higher in women and in the oldest people. CONCLUSIONS Our incidence and prevalence estimations were slightly lower than the recent face-to-face studies conducted in Spain and higher than other analyses of electronic health data from other European populations. Real-world data routinely collected in primary care settings could be a powerful tool to study the epidemiology of AD.
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Affiliation(s)
- Anna Ponjoan
- Vascular Health Research Group (ISV-Girona), Jordi Gol Institute for Primary Care Research (IDIAPJGol), Barcelona, Catalonia, Spain
- Girona Biomedical Research Institute (IDIBGi), Girona, Catalonia, Spain
- Autonomous University of Barcelona, Bellaterra (Cerdanyola del Vallès), Catalonia, Spain
| | - Josep Garre-Olmo
- Girona Biomedical Research Institute (IDIBGi), Girona, Catalonia, Spain
| | - Jordi Blanch
- Vascular Health Research Group (ISV-Girona), Jordi Gol Institute for Primary Care Research (IDIAPJGol), Barcelona, Catalonia, Spain
| | - Ester Fages
- Vascular Health Research Group (ISV-Girona), Jordi Gol Institute for Primary Care Research (IDIAPJGol), Barcelona, Catalonia, Spain
- Primary Care Services, Catalan Institute of Health (ICS), Girona, Catalonia, Spain
| | - Lia Alves-Cabratosa
- Vascular Health Research Group (ISV-Girona), Jordi Gol Institute for Primary Care Research (IDIAPJGol), Barcelona, Catalonia, Spain
| | - Ruth Martí-Lluch
- Vascular Health Research Group (ISV-Girona), Jordi Gol Institute for Primary Care Research (IDIAPJGol), Barcelona, Catalonia, Spain
- Girona Biomedical Research Institute (IDIBGi), Girona, Catalonia, Spain
- Autonomous University of Barcelona, Bellaterra (Cerdanyola del Vallès), Catalonia, Spain
| | - Marc Comas-Cufí
- Vascular Health Research Group (ISV-Girona), Jordi Gol Institute for Primary Care Research (IDIAPJGol), Barcelona, Catalonia, Spain
| | - Dídac Parramon
- Vascular Health Research Group (ISV-Girona), Jordi Gol Institute for Primary Care Research (IDIAPJGol), Barcelona, Catalonia, Spain
- Primary Care Services, Catalan Institute of Health (ICS), Girona, Catalonia, Spain
| | - María Garcia-Gil
- Vascular Health Research Group (ISV-Girona), Jordi Gol Institute for Primary Care Research (IDIAPJGol), Barcelona, Catalonia, Spain
| | - Rafel Ramos
- Vascular Health Research Group (ISV-Girona), Jordi Gol Institute for Primary Care Research (IDIAPJGol), Barcelona, Catalonia, Spain.
- Department of Medical Sciences, School of Medicine, Campus Salut, University of Girona, Girona, Catalonia, Spain.
- IDIAPJGol, c/ Maluquer Salvador, 11 baixos, 17002, Girona, Catalonia, Spain.
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Ponjoan A, Garre-Olmo J, Blanch J, Fages E, Alves-Cabratosa L, Martí-Lluch R, Comas-Cufí M, Parramon D, Garcia-Gil M, Ramos R. Epidemiology of dementia: prevalence and incidence estimates using validated electronic health records from primary care. Clin Epidemiol 2019; 11:217-228. [PMID: 30881138 PMCID: PMC6407519 DOI: 10.2147/clep.s186590] [Citation(s) in RCA: 55] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023] Open
Abstract
Purpose Updated estimates of incidence and prevalence of dementia are crucial to ensure adequate public health policy. However, most of the epidemiological studies in the population in Spain were conducted before 2010. This study assessed the validity of dementia diagnoses recorded in electronic health records contained in a large primary-care database to determine if they could be used for research purposes. Then, to update the epidemiology of dementia in Catalonia (Spain), we estimated crude and standardized prevalence and incidence rates of dementia in Catalonia in 2016. Methods The System for the Development of Research in Primary Care (SIDIAP) database contains anonymized information for >80% of the Catalan population. Validity of dementia codes in SIDIAP was assessed in patients at least 40 years old by asking general practitioners for additional evidence to support the diagnosis. Crude and standardized incidence and prevalence (95% CI) in people aged ≥65 years were estimated assuming a Poisson distribution. Results The positive predictive value of dementia diagnoses recorded in SIDIAP was estimated as 91.0% (95% CI 87.5%–94.5%). Age-and sex-standardized incidence and prevalence of dementia were 8.6/1,000 person-years (95% CI 8.0–9.3) and 5.1% (95% CI 4.5%–5.7%), respectively. Conclusion SIDIAP contains valid dementia records. We observed incidence and prevalence estimations similar to recent face-to-face studies conducted in Spain and higher than studies using electronic health data from other European populations.
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Affiliation(s)
- Anna Ponjoan
- Vascular Health Research Group (ISV-Girona), Jordi Gol Institute for Primary Care Research (IDIAPJGol), Barcelona, Catalonia, Spain, .,Girona Biomedical Research Institute (IDIBGI), Girona, Catalonia, Spain.,Santa Clara Primary Care Health Center, Catalan Health Institute, Girona, Catalonia, Spain
| | - Josep Garre-Olmo
- Girona Biomedical Research Institute (IDIBGI), Girona, Catalonia, Spain
| | - Jordi Blanch
- Vascular Health Research Group (ISV-Girona), Jordi Gol Institute for Primary Care Research (IDIAPJGol), Barcelona, Catalonia, Spain,
| | - Ester Fages
- Vascular Health Research Group (ISV-Girona), Jordi Gol Institute for Primary Care Research (IDIAPJGol), Barcelona, Catalonia, Spain,
| | - Lia Alves-Cabratosa
- Vascular Health Research Group (ISV-Girona), Jordi Gol Institute for Primary Care Research (IDIAPJGol), Barcelona, Catalonia, Spain,
| | - Ruth Martí-Lluch
- Vascular Health Research Group (ISV-Girona), Jordi Gol Institute for Primary Care Research (IDIAPJGol), Barcelona, Catalonia, Spain, .,Girona Biomedical Research Institute (IDIBGI), Girona, Catalonia, Spain.,Santa Clara Primary Care Health Center, Catalan Health Institute, Girona, Catalonia, Spain
| | - Marc Comas-Cufí
- Vascular Health Research Group (ISV-Girona), Jordi Gol Institute for Primary Care Research (IDIAPJGol), Barcelona, Catalonia, Spain,
| | - Dídac Parramon
- Vascular Health Research Group (ISV-Girona), Jordi Gol Institute for Primary Care Research (IDIAPJGol), Barcelona, Catalonia, Spain, .,Autonomous University of Barcelona, Bellaterra (Cerdanyola del Vallès), Catalonia, Spain
| | - María Garcia-Gil
- Vascular Health Research Group (ISV-Girona), Jordi Gol Institute for Primary Care Research (IDIAPJGol), Barcelona, Catalonia, Spain,
| | - Rafel Ramos
- Vascular Health Research Group (ISV-Girona), Jordi Gol Institute for Primary Care Research (IDIAPJGol), Barcelona, Catalonia, Spain, .,Department of Medical Sciences, School of Medicine, Campus Salut, University of Girona, Girona, Catalonia, Spain,
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3
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Roman Degano I, Ramos R, Garcia-Gil M, Zamora A, Comas-Cufi M, Frances A, Marrugat J. P6258Higher cardiovascular disease incidence by increasing number of vascular territories affected and hypercholesterolemia level in population with existing cardiovascular disease. Eur Heart J 2018. [DOI: 10.1093/eurheartj/ehy566.p6258] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Affiliation(s)
- I Roman Degano
- Hospital del Mar, Municipal Institute for Medical Research (IMIM), Barcelona, Spain
| | - R Ramos
- Primary Care Research Institute (IDIAP), Barcelona, Spain
| | - M Garcia-Gil
- Primary Care Research Institute (IDIAP), Barcelona, Spain
| | - A Zamora
- University of Girona, Medical Sciences, Girona, Spain
| | - M Comas-Cufi
- Primary Care Research Institute (IDIAP), Barcelona, Spain
| | | | - J Marrugat
- CIBERCV, Health Institute Carlos III/Hospital del Mar Medical Research Institute (IMIM), Madrid/Barcelona, Spain
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4
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Fina-Aviles F, Medina-Peralta M, Mendez-Boo L, Hermosilla E, Elorza JM, Garcia-Gil M, Ramos R, Bolibar B, Javaid MK, Edwards CJ, Cooper C, Arden NK, Prieto-Alhambra D. The descriptive epidemiology of rheumatoid arthritis in Catalonia: a retrospective study using routinely collected data. Clin Rheumatol 2014; 35:751-7. [PMID: 25344777 DOI: 10.1007/s10067-014-2801-1] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2014] [Revised: 10/01/2014] [Accepted: 10/12/2014] [Indexed: 10/24/2022]
Abstract
Information on the epidemiology of rheumatoid arthritis (RA) in Southern Europe is scarce. We estimated the age- and gender-adjusted incidence and prevalence of RA in Catalonia using routinely collected primary care records. We identified incident (2009-2012) and prevalent (on 31 December 2012) cases of RA in the SIDIAP database using ICD-10 codes. SIDIAP contains anonymized data from computerized primary care records for about five million adults (>80 % of the population). We estimated age- (5-year groups) and gender-specific, and directly standardized incidence and prevalence of RA and confidence intervals (95% CIs) assuming a Poisson distribution. A total of 20,091 prevalent (among whom 5,796 incident) cases of RA were identified among 4,796,498 study participants observed for up to 4 years. Rates of RA increased with age in both genders, peaking at the age of 65-70 years. Age- and gender-standardized incidence and prevalence rates were 0.20/1,000 person-years (95% CI 0.19-0.20) and 4.17/1,000 (4.11-4.23) respectively. Rheumatoid factor was positive (≥10 IU/mL) in 1,833 (73.9 %) of 2,482 cases tested in primary care. The incidence and prevalence of RA in Catalonia are similar to those of other Southern European regions, and lower than those of northern areas. This data will inform health care planning and resource allocation.
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Affiliation(s)
- F Fina-Aviles
- Primary Care Department, Institut Català de la Salut, Av Gran Via de les Corts Catalanes 587, 3rd floor, 08007, Barcelona, Spain
| | - M Medina-Peralta
- Primary Care Department, Institut Català de la Salut, Av Gran Via de les Corts Catalanes 587, 3rd floor, 08007, Barcelona, Spain
| | - L Mendez-Boo
- Primary Care Department, Institut Català de la Salut, Av Gran Via de les Corts Catalanes 587, 3rd floor, 08007, Barcelona, Spain
| | - E Hermosilla
- IDIAP Jordi Gol Primary Care Research Institute, Universitat Autònoma de Barcelona, Av Gran Via de les Corts Catalanes 587, Atic, 08007, Barcelona, Spain
| | - J M Elorza
- IDIAP Jordi Gol Primary Care Research Institute, Universitat Autònoma de Barcelona, Av Gran Via de les Corts Catalanes 587, Atic, 08007, Barcelona, Spain
| | - M Garcia-Gil
- Primary Care Department, Institut Català de la Salut, Av Gran Via de les Corts Catalanes 587, 3rd floor, 08007, Barcelona, Spain.,IDIAP Jordi Gol Primary Care Research Institute, Universitat Autònoma de Barcelona, Av Gran Via de les Corts Catalanes 587, Atic, 08007, Barcelona, Spain
| | - R Ramos
- Primary Care Department, Institut Català de la Salut, Av Gran Via de les Corts Catalanes 587, 3rd floor, 08007, Barcelona, Spain.,IDIAP Jordi Gol Primary Care Research Institute, Universitat Autònoma de Barcelona, Av Gran Via de les Corts Catalanes 587, Atic, 08007, Barcelona, Spain
| | - B Bolibar
- IDIAP Jordi Gol Primary Care Research Institute, Universitat Autònoma de Barcelona, Av Gran Via de les Corts Catalanes 587, Atic, 08007, Barcelona, Spain
| | - M K Javaid
- Oxford NIHR Musculoskeletal Biomedical Research Unit, Nuffield Department of Orthopaedics, Rheumatology and Musculoskeletal Sciences, University of Oxford, Windmill Road, OX3 7LD, Oxford, UK.,MRC Lifecourse Epidemiology Unit, University of Southampton, Tremona Road, SO16 6YD, Southampton, UK
| | - C J Edwards
- Southampton General Hospital, Tremona Road, SO16 6YD, Southampton, UK
| | - C Cooper
- Oxford NIHR Musculoskeletal Biomedical Research Unit, Nuffield Department of Orthopaedics, Rheumatology and Musculoskeletal Sciences, University of Oxford, Windmill Road, OX3 7LD, Oxford, UK.,MRC Lifecourse Epidemiology Unit, University of Southampton, Tremona Road, SO16 6YD, Southampton, UK
| | - N K Arden
- Oxford NIHR Musculoskeletal Biomedical Research Unit, Nuffield Department of Orthopaedics, Rheumatology and Musculoskeletal Sciences, University of Oxford, Windmill Road, OX3 7LD, Oxford, UK.,MRC Lifecourse Epidemiology Unit, University of Southampton, Tremona Road, SO16 6YD, Southampton, UK
| | - D Prieto-Alhambra
- IDIAP Jordi Gol Primary Care Research Institute, Universitat Autònoma de Barcelona, Av Gran Via de les Corts Catalanes 587, Atic, 08007, Barcelona, Spain. .,Oxford NIHR Musculoskeletal Biomedical Research Unit, Nuffield Department of Orthopaedics, Rheumatology and Musculoskeletal Sciences, University of Oxford, Windmill Road, OX3 7LD, Oxford, UK. .,MRC Lifecourse Epidemiology Unit, University of Southampton, Tremona Road, SO16 6YD, Southampton, UK. .,SIDIAP Database, IDIAP Jordi Gol, Av Gran Via Corts Catalanes, 587, Atic, 08007, Barcelona, Spain.
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Castellanos M, Sobrino T, Pedraza S, Moldes O, Pumar JM, Silva Y, Serena J, Garcia-Gil M, Castillo J, Davalos A. High plasma glutamate concentrations are associated with infarct growth in acute ischemic stroke. Neurology 2008; 71:1862-8. [DOI: 10.1212/01.wnl.0000326064.42186.7e] [Citation(s) in RCA: 69] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
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Garcia-Gil M, Bertini F, Pesi R, Voccoli V, Tozzi MG, Camici M. 5 '-Amino-4-imidazolecarboxamide riboside induces apoptosis in human neuroblastoma cells via the mitochondrial pathway. Nucleosides Nucleotides Nucleic Acids 2007; 25:1265-70. [PMID: 17065104 DOI: 10.1080/15257770600890905] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
Abstract
5'-Amino-4-imidazolecarboxamide (AICA) riboside induces apoptosis in neuronal cell models. In order to exert its effect, AICA riboside must enter the cell and be phosphorylated to the ribotide. In the present work, we have further studied the mechanism of apoptosis induced by AICA riboside. The results demonstrate that AICA riboside activates AMP-dependent protein kinase (AMPK), induces release of cytochrome c from mitochondria and activation of caspase 9. The role of AMPK in determining cell fate is controversial. In fact, AICA riboside has been reported to be neuroprotective or to induce apoptosis depending on its concentration, cell type or apoptotic stimuli used. In order to clarify whether the activation of AMPK is related to apoptosis in our model, we have used another AMPK stimulator, metformin, and we have analysed its effects on cell viability, nuclear morphology and AMPK activity. Five mM metformin increased AMPK activity, inhibited viability, and increased the number of apoptotic nuclei. AICA riboside, which can be generated from the ribotide (an intermediate of the purine de novo synthesis) by the action of the ubiquitous cytosolic 5'-nucleotidase (cN-II), may accumulate in those individuals in which an inborn error of purine metabolism causes both a building up of intermediates and/or an increase of the rate of de novo synthesis, and/or an overexpression of cN-II. Therefore, our results suggest that the toxic effect of AICA riboside on some types of neurons may participate in the neurological manifestations of syndromes related to purine dismetabolisms.
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Affiliation(s)
- M Garcia-Gil
- Department of Biology, University of Pisa, Pisa, Italy
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7
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Cervia D, Martini D, Garcia-Gil M, Di Giuseppe G, Guella G, Dini F, Bagnoli P. Cytotoxic effects and apoptotic signalling mechanisms of the sesquiterpenoid euplotin C, a secondary metabolite of the marine ciliate Euplotes crassus, in tumour cells. Apoptosis 2006; 11:829-43. [PMID: 16534550 DOI: 10.1007/s10495-006-5700-3] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
Most antitumour agents with cytotoxic properties induce apoptosis. The lipophilic compound euplotin C, isolated from the ciliate Euplotes crassus, is toxic to a number of different opportunistic or pathogenic microorganisms, although its mechanism of action is currently unknown. We report here that euplotin C is a powerful cytotoxic and pro-apoptotic agent in mouse AtT-20 and rat PC12 tumour-derived cell lines. In addition, we provide evidence that euplotin C treatment results in rapid activation of ryanodine receptors, depletion of Ca2+ stores in the endoplasmic reticulum (ER), the release of cytochrome c from the mitochondria, activation of caspase-12, and activation of caspase-3, leading to apoptosis. Intracellular Ca2+ overload is an early event which induces apoptosis and is parallelled by ER stress and the release of cytochrome c, whereas caspase-12 may be activated by euplotin C at a later stage in the apoptosis pathway. These events, either independently or concomitantly, lead to the activation of the caspase-3 and its downstream effectors, triggering the cell to undergo apoptosis. These results demonstrate that euplotin C may be considered for the design of cytotoxic and pro-apoptotic new drugs.
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Affiliation(s)
- D Cervia
- Dipartimento di Fisiologia e Biochimica G. Moruzzi, via S. Zeno, 56127, Pisa, Italy.
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8
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Garcia-Gil M, Pesi R, Perna S, Allegrini S, Giannecchini M, Camici M, Tozzi MG. 5'-aminoimidazole-4-carboxamide riboside induces apoptosis in human neuroblastoma cells. Neuroscience 2003; 117:811-20. [PMID: 12654334 DOI: 10.1016/s0306-4522(02)00836-9] [Citation(s) in RCA: 100] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
5'-Aminoimidazole-4-carboxamide riboside (AICA riboside) has been previously shown to be toxic to two neuronal cell models [Neuroreport 11 (2000) 1827]. In this paper we demonstrate that AICA riboside promotes apoptosis in undifferentiated human neuroblastoma cells (SH-SY5Y), inducing a raise in caspase-3 activity. In order to exert its effect on viability, AICA riboside must enter the cells and be phosphorylated to the ribotide, since both a nucleoside transport inhibitor, and an inhibitor of adenosine kinase produce an enhancement of the viability of AICA riboside-treated cells. Short-term incubations (2 h) with AICA riboside result in five-fold increase in the activity of AMP-dependent protein kinase (AMPK). However, the activity of AMPK is not significantly affected at prolonged incubations (48 h), when the apoptotic effect of AICA riboside is evident. The results demonstrate that when the cell line is induced to differentiate both toward a cholinergic phenotype (with retinoic acid) or a noradrenergic phenotype (with phorbol esters), the toxic effect is significantly reduced, and in the case of the noradrenergic phenotype differentiation, the riboside is completely ineffective in promoting apoptosis. This reduction of effect correlates with an overexpression of Bcl-2 during differentiation. AICA riboside, derived from the hydrolysis of the ribotide, an intermediate of purine de novo synthesis, is absent in normal healthy cells; however it may accumulate in those individuals in which an inborn error of purine metabolism causes an increase in the rate of de novo synthesis and/or an overexpression of cytosolic 5'-nucleotidase, that appears to be the enzyme responsible for AICA ribotide hydrolysis. In fact, 5'-nucleotidase activity has been shown to increase in patients affected by Lesch-Nyhan syndrome in which both acceleration of de novo synthesis and accumulation of AICA ribotide has been described, and also in other neurological disorders of unknown etiology. Our results raise the intriguing clue that the neurotoxic effect of AICA riboside on the developing brain might contribute to the neurological manifestations of syndromes related to purine dismetabolisms.
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Affiliation(s)
- M Garcia-Gil
- Dipartimento di Fisiologia e Biochimica, Università di Pisa, Via S. Maria, 55 56100, Pisa, Italy.
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Abstract
1. In this paper the authors tested the effect of caulerpenyne (CYN), a sesquiterpene synthesized by the green alga Caulerpa taxifolia onto the central nervous system of the leech Hirudo medicinalis. Investigations have been performed with three different approaches: neuroethological, electrophysiological and neurochemical techniques. 2. CYN application mimics the effect of a nociceptive stimulation (brushing), eliciting a clear-cut potentiation of the animal swim response to the test stimulus (non associative learning process such as sensitization). This effect is similar to that one induced by the endogenous neurotransmitter serotonin (5HT). 3. CYN strongly reduces the after-hyperpolarization (AHP) recorded from T sensory neurons. This effect overlaps that one produced by 5HT, but it is not affected by the serotonergic antagonist methysergide. 4. The decrease of AHP amplitude due to CYN application is observed also in presence of apamin, a blocking agent of Ca++-dependent K+ channels, suggesting that CYN is acting through the inhibition of the Na+/K+ electrogenic pump. 5. The depression of the AHP driven by CYN is not prevented by application of MDL 12330A, an adenylate cyclase inhibitor. On the other hand MDL 12330A counteracts the reduction of AHP due to 5HT application. 6. Incubation of the leech central nervous system with CYN induces the phosphorylation of proteins of 29, 50, 66 and 100 kDa. This pattern of phosphorylation is similar to that one elicited by 5HT treatment. 7. The data demonstrate that CYN exerts remarkable effects on leech neurons by acting onto specific molecular targets such as the Na+/K+ ATPase. This effect may influence important neural integrative functions and may explain the sensitizing action produced by the toxin on swim induction. Finally, caulerpenyne does not act through the pathways involved in the 5HT action, and its effect is not mediated by the second messenger cyclic AMP. The mechanism of action of CYN are still under investigations.
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Affiliation(s)
- M Brunelli
- Dipartimento di Fisiologia e Biochimica G. Moruzzi, Università di Pisa, Italy.
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10
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Pesi R, Micheli V, Jacomelli G, Peruzzi L, Camici M, Garcia-Gil M, Allegrini S, Tozzi MG. Cytosolic 5'-nucleotidase hyperactivity in erythrocytes of Lesch-Nyhan syndrome patients. Neuroreport 2000; 11:1827-31. [PMID: 10884027 DOI: 10.1097/00001756-200006260-00006] [Citation(s) in RCA: 42] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
Lesch-Nyhan syndrome is a metabolic-neurological syndrome caused by the X-linked deficiency of the purine salvage enzyme hypoxanthine-guanine phosphoribosyltransferase (HGPRT). Metabolic consequences of HGPRT deficiency have been clarified, but the connection with the neurological manifestations is still unknown. Much effort has been directed to finding other alterations in purine nucleotides in different cells of Lesch-Nyhan patients. A peculiar finding was the measure of appreciable amount of Z-nucleotides in red cells. We found significantly higher IMP-GMP-specific 5'-nucleotidase activity in the erythrocytes of seven patients with Lesch-Nyhan syndrome than in healthy controls. The same alteration was found in one individual with partial HGPRT deficiency displaying a severe neurological syndrome, and in two slightly hyperuricemic patients with a psychomotor delay. Since ZMP was a good substrate of 5'-nucleotidase producing Z-riboside, we incubated murine and human cultured neuronal cells with this nucleoside and found that it is toxic for our models, promoting apoptosis. This finding suggests an involvement of the toxicity of the Z-riboside in the pathogenesis of neurological disorders in Lesch-Nyhan syndrome and possibly in other pediatric neurological syndromes of uncertain origin.
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Affiliation(s)
- R Pesi
- Dipartimento di Fisiologia e Biochimica, Università di Pisa, Italy
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11
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Abstract
There is increasing evidence that sphingolipids are involved in cell survival, differentiation or commitment to death. The effect of different sphingolipids and inhibitors of mitogen-activated protein kinase (MAPK) cascade on SH-SY5Y neuroblastoma cell death has been studied. Permeant ceramide analogues C2-Cer, C8-Cer, and C8-Cer-1-phosphate, but not dihydro C2-Cer induce apoptosis, as shown by Hoechst staining. Inhibition of ceramidase and sphingosine kinase, as well as incubation with sphingosine, decreases cell viability, measured as 3-(4,5-dimethylthiazol-2-yl)-2, 5-diphenyltetrazolium bromide reduction, whereas addition of sphingosine-1-phosphate increases proliferation. Both PD98059 (MAPKK inhibitor) and SB202190 (p38 MAPK inhibitor) decreased viability, but only SB202190 abolished the effect of ceramide. These results suggest that in SH-SY5Y neuroblastoma cells, death is signalled by increases in ceramide, ceramide-phosphate or sphingosine content through p38 MAPK pathway while survival requires MAPK and high sphingosine-1-phosphate/ceramide ratio.
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Affiliation(s)
- S Tavarini
- Departments of Physiology and Biochemistry, University of Pisa, via S. Zeno 31, 56127, Pisa, Italy
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12
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Brunelli M, Garcia-Gil M, Mozzachiodi R, Scuri R, Zaccardi ML. Neurobiological principles of learning and memory. Arch Ital Biol 1997; 135:15-36. [PMID: 9139580] [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] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
An increasing flow of evidences collected on elementary forms of learning processes in selected animal models evidentiates some mechanisms which can represent the basic cellular principles underlying plastic changes: 1. 5HT and second messengers of nucleotide type (like cAMP) have a pivotal role in the learning process. 2. In almost all short-term learning processes the modifications are subserved by a mechanism of protein phosphorylation. 3. In various animal models the modulation of K+ and Ca2+ channels is the molecular mechanism for learning. Experiments performed in sensory T neuron of the leech indicate that the modulation of Na+/K+ electrogenic pump is one of the fundamental mechanism for learning. 4. In long-term plastic changes, the most important finding is that newly synthesized proteins are formed. 5. In addition to what has been observed in the Aplysia model, where changes in synaptic efficacy represent the basic principles of memory storage, in the leech it has been demonstrated that a molecular machinery present in a single neuron can adapt the activity of the cell to environmental stimuli.
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Affiliation(s)
- M Brunelli
- Dipartimento di Fisiologia e Biochimica G. Moruzzi, Università degli Studi di Pisa, Italia
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Sanz C, Leon Y, Garcia-Gil M, Varela-Nieto I. Role of Raf kinases during inner ear development. Int J Dev Biol 1996; Suppl 1:83S-84S. [PMID: 9087707] [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] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Affiliation(s)
- C Sanz
- Instituto de Investigaciones Biomédicas, CSIC, Madrid, Spain
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Garcia-Gil M, Bottai D, Romano A, Fineschi L, Bini L, Pallini V, Brunelli M. Repetitive treatment with serotonin modifies protein synthesis and protein phosphorylation in the central nervous system of Hirudo medicinalis. Electrophoresis 1995; 16:1251-4. [PMID: 7498173 DOI: 10.1002/elps.11501601206] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
Abstract
Serotonin (5HT) is the neurotransmitter involved in some forms of short-term memory in the leech. Behavioral experiments have demonstrated that long-term memory requires new protein synthesis. With the aim of studying the molecular mechanism underlying memory processes in the leech, we have analyzed the effect of 5HT on protein synthesis and protein phosphorylation. Segmental ganglia of the leech central nervous system have been labeled, proteins have been separated by two-dimensional-electrophoresis and labeled proteins detected by autoradiography. Our findings indicate that repetitive treatment with 5HT produces either the persistence of phosphorylation or changes in protein synthesis in several proteins.
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Affiliation(s)
- M Garcia-Gil
- Department of Physiology and Biochemistry, University of Pisa, Italia
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Bottai D, Garcia-Gil M, Zaccardi ML, Fineschi L, Brunelli M. Interleukin-1 and interleukin-6 modify protein phosphorylation in the central nervous system of Hirudo medicinalis. Brain Res 1994; 641:155-9. [PMID: 8019842 DOI: 10.1016/0006-8993(94)91830-9] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
Recent data suggest that IL-1-like molecules have been conserved during evolution. The signal transduction mechanism of IL-1 is not known, but kinase activation has been reported. With the aim of studying if human IL-1 has any effect on the leech nervous system, we have added this cytokine to segmental ganglia labeled with [32P]ortophosphoric acid; proteins have been separated by electrophoresis and phosphoproteins detected by autoradiography. In the present paper we show that human IL-1 and IL-6 are able to induce changes on protein phosphorylation in the leech central nervous system and that these changes are similar to those ones induced by the neurotransmitter serotonin.
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Affiliation(s)
- D Bottai
- Department of Physiology and Biochemistry G. Moruzzi, University of Pisa, Italy
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Garcia-Gil M, Bottai D, Zaccardi ML, Cannizzaro M, Brunelli M. Effect of serotonin on protein phosphorylation in the central nervous system of the leech Hirudo medicinalis. Comp Biochem Physiol C Comp Pharmacol Toxicol 1993; 104:125-31. [PMID: 8097446 DOI: 10.1016/0742-8413(93)90123-3] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
1. Phosphoproteins of different regions of the Hirudo medicinalis central nervous system have been analysed by means of two-dimensional electrophoresis. 2. Serotonin, 8-Br-cAMP and phorbol 12,13-dibutyrate stimulate phosphorylation of a number of proteins whose isoelectric points and molecular weights are presented. 3. A group of proteins of 78 kDa and pI = 6-6.5, whose level of phosphorylation increases in the presence of serotonin, 8-Br-cAMP and phorbol ester, is observed only in segmental but not in cephalic or caudal ganglia. 4. The putative roles of these phosphoproteins are discussed.
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Affiliation(s)
- M Garcia-Gil
- Department of Physiology and Biochemistry, University of Pisa, Italy
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Bottai D, Garcia-Gil M, Zaccardi M, Puopolo M, Cannizzaro M, Brunelli M. Effect of serotonin on protein phosphorylation and protein synthesis in the CNS of “hirudo medicinalis”. Neurochem Int 1992. [DOI: 10.1016/0197-0186(92)92017-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
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Garcia-Gil M, Cipollini G, Cattani M, Bottai D, Brunelli M. Protein kinase C activity in the central nervous system of the leech, Hirudo medicinalis. ACTA ACUST UNITED AC 1991. [DOI: 10.1016/0305-0491(91)90008-2] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
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19
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Garcia-Gil M, Bottai D, Cannizzaro M, Brunelli M. Effect of phorbol ester on protein phosphorylation in the central nervous system of the leech Hirudo medicinalis: a two-dimensional electrophoretical analysis. Comp Biochem Physiol B 1991; 99:859-64. [PMID: 1790678 DOI: 10.1016/0305-0491(91)90154-6] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
1. Proteins of different regions of the Hirudo medicinalis central nervous system have been analyzed by means of two-dimensional electrophoresis. 2. Subcellular distribution of phosphoproteins has been studied in leech segmental ganglia. 3. Phorbol 12,13-dibutyrate, a protein kinase C activator, stimulates the phosphorylation of a number of proteins whose isoelectric points and mol. wts are presented. 4. Putative roles for these phosphoproteins are discussed.
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Affiliation(s)
- M Garcia-Gil
- Department of Physiology and Biochemistry, University of Pisa, Italy
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Catarsi S, Garcia-Gil M, Traina G, Brunelli M. Seasonal variation of serotonin content and nonassociative learning of swim induction in the leech Hirudo medicinalis. J Comp Physiol A Neuroethol Sens Neural Behav Physiol 1990; 167:469-74. [PMID: 2258835 DOI: 10.1007/bf00190817] [Citation(s) in RCA: 24] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
It is possible to obtain habituation of swim induction by stimulating the leech with repetitive light electrical trains. After obtaining this simple form of non-associative learning, it is also possible to potentiate its response by a series of nociceptive skin brushings (dishabituation). Serotonin applied to the animal is the only neurotransmitter found to mimick dishabituation. We have observed that in the period April-June most animals did not exhibit potentiation of the swimming response after nociceptive stimulation while injection of serotonin mimicked dishabituation as in the animals treated in the period October-March. We have seen correlation between the changes in nonassociative learning and the seasonal variation of serotonin levels in segmental ganglia. This finding strengthens the hypothesis of serotonin as the neurotransmitter mediating dishabituation in swim induction of the leech.
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Affiliation(s)
- S Catarsi
- Department of Physiology and Biochemistry, University of Pisa, Italy
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Garcia-Gil M, Berton F, Tongiorgi E, Brunelli M. Effects of cyclic nucleotides and calcium/calmodulin on protein phosphorylation in the CNS of Hirudo medicinalis. J Neurochem 1989; 52:699-704. [PMID: 2465376 DOI: 10.1111/j.1471-4159.1989.tb02511.x] [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: 01/01/2023]
Abstract
Protein phosphorylation plays an important role in the regulation of neural functions. We have studied the phosphorylation of proteins in homogenates of segmental ganglia of the leech Hirudo medicinalis. We describe a number of proteins whose phosphorylation is dependent on calcium/calmodulin or cyclic nucleotides. Most of the proteins whose phosphorylation is increased in the presence of calcium seem to be substrates for cyclic nucleotide-dependent protein kinases. Only two of the phosphoproteins described appear to be specific substrates for calcium/calmodulin protein kinase(s), and at least six phosphoproteins appear to be specific substrates for cyclic nucleotide-dependent kinase(s). The leech nervous system, with large and identifiable neurons, provides a good tool for studies of neural functions, such as learning. The results are discussed in the context of the role of protein phosphorylation on learning processes.
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Affiliation(s)
- M Garcia-Gil
- Department of Physiology and Biochemistry, University of Pisa, Italy
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Berenstein EH, Garcia-Gil M, Siraganian RP. Dexamethasone inhibits receptor-activated phosphoinositide breakdown in rat basophilic leukemia (RBL-2H3) cells. The Journal of Immunology 1987. [DOI: 10.4049/jimmunol.138.6.1914] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
Abstract
The activation of rat basophilic leukemia cells for histamine release is accompanied by Ca2+ influx and arachidonic acid release. IgE receptor but not A23187 ionophore stimulation of these cells also resulted in phosphoinositide breakdown. In these experiments, the culture of these cells with dexamethasone inhibited IgE- and ionophore-mediated histamine release. The concentration for 50% of maximal inhibition was 12 nM, and prolonged exposure to the drug was required, with maximal effect observed in 8 to 15 hr. The inhibitory effect of dexamethasone was reversible (t1/2 for recovery was 16 hr). Dexamethasone blocked the IgE-mediated 45Ca2+ influx and the release of [14C]-arachidonic acid (IC50 of 1 nM and 10 nM respectively). Dexamethasone inhibited the IgE receptor-mediated phosphoinositide breakdown (IC50 of 5 nM). It also decreased arachidonic acid release after A23187 stimulation demonstrating an effect on phospholipase A2. Therefore, exposure of the cells to dexamethasone results in the inhibition of both phospholipase A2 and phospholipase C pathways of arachidonic acid generation.
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Berenstein EH, Garcia-Gil M, Siraganian RP. Dexamethasone inhibits receptor-activated phosphoinositide breakdown in rat basophilic leukemia (RBL-2H3) cells. J Immunol 1987; 138:1914-8. [PMID: 2434566] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
The activation of rat basophilic leukemia cells for histamine release is accompanied by Ca2+ influx and arachidonic acid release. IgE receptor but not A23187 ionophore stimulation of these cells also resulted in phosphoinositide breakdown. In these experiments, the culture of these cells with dexamethasone inhibited IgE- and ionophore-mediated histamine release. The concentration for 50% of maximal inhibition was 12 nM, and prolonged exposure to the drug was required, with maximal effect observed in 8 to 15 hr. The inhibitory effect of dexamethasone was reversible (t1/2 for recovery was 16 hr). Dexamethasone blocked the IgE-mediated 45Ca2+ influx and the release of [14C]-arachidonic acid (IC50 of 1 nM and 10 nM respectively). Dexamethasone inhibited the IgE receptor-mediated phosphoinositide breakdown (IC50 of 5 nM). It also decreased arachidonic acid release after A23187 stimulation demonstrating an effect on phospholipase A2. Therefore, exposure of the cells to dexamethasone results in the inhibition of both phospholipase A2 and phospholipase C pathways of arachidonic acid generation.
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Garcia-Gil M, Siraganian RP. Source of the arachidonic acid released on stimulation of rat basophilic leukemia cells. J Immunol 1986; 136:3825-8. [PMID: 2422263] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
Triggering of rat basophilic leukemia cells for histamine secretion is accompanied by arachidonic acid release. We studied the source of this arachidonic acid released after IgE or calcium ionophore A23187 stimulation. The 48-hr culture of the cells with [14C]arachidonic acid resulted in labeling of the phospholipids to constant specific activity. After IgE stimulation, 8.8% of the cellular [14C]arachidonate was released; this was predominantly from phosphatidylinositol (PI)/phosphatidylserine (PS) (66.3%), less from phosphatidylethanolamine (PE) (25.9%), and minimally from phosphatidylcholine (PC). In contrast, after ionophore stimulation the cells released 16.4% of cellular [14C]arachidonate, most of this was from PE (55.4%) followed by about equal amounts from PS/PI and PC (24% and 20%, respectively). Therefore, the source of the released arachidonic acid depends on the stimulus. In contrast, the results are different when the cells are cultured for only 2 hr with [14C]arachidonic acid. The label in phospholipids was in PC (44%), PE (38%), and PI/PS (20%); the stimulation of the cells with IgE or ionophore resulted in the release of the [14C]arachidonate from PC (81% and 96%, respectively). This suggests the presence of several pools of phospholipids that are labeled at different rates and have variable proximity and/or accessibility to the phospholipase(s) enzyme(s) activated during cell secretion.
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Garcia-Gil M, Siraganian RP. Source of the arachidonic acid released on stimulation of rat basophilic leukemia cells. The Journal of Immunology 1986. [DOI: 10.4049/jimmunol.136.10.3825] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
Abstract
Triggering of rat basophilic leukemia cells for histamine secretion is accompanied by arachidonic acid release. We studied the source of this arachidonic acid released after IgE or calcium ionophore A23187 stimulation. The 48-hr culture of the cells with [14C]arachidonic acid resulted in labeling of the phospholipids to constant specific activity. After IgE stimulation, 8.8% of the cellular [14C]arachidonate was released; this was predominantly from phosphatidylinositol (PI)/phosphatidylserine (PS) (66.3%), less from phosphatidylethanolamine (PE) (25.9%), and minimally from phosphatidylcholine (PC). In contrast, after ionophore stimulation the cells released 16.4% of cellular [14C]arachidonate, most of this was from PE (55.4%) followed by about equal amounts from PS/PI and PC (24% and 20%, respectively). Therefore, the source of the released arachidonic acid depends on the stimulus. In contrast, the results are different when the cells are cultured for only 2 hr with [14C]arachidonic acid. The label in phospholipids was in PC (44%), PE (38%), and PI/PS (20%); the stimulation of the cells with IgE or ionophore resulted in the release of the [14C]arachidonate from PC (81% and 96%, respectively). This suggests the presence of several pools of phospholipids that are labeled at different rates and have variable proximity and/or accessibility to the phospholipase(s) enzyme(s) activated during cell secretion.
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Garcia-Gil M, Siraganian RP. Phospholipase A2 stimulation during cell secretion in rat basophilic leukemia cells. J Immunol 1986; 136:259-63. [PMID: 2415621] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
The bridging of IgE receptors on rat basophilic leukemia cells (RBL-2H3) results in a number of biochemical events that accompany histamine secretion. Prominent among these is the release of arachidonic acid from cellular phospholipids, which could be due to the activation of phospholipase enzymes. In the present experiments we studied the intracellular activation of phospholipase A2 (PLA2) during histamine release. RBL-2H3 cells were stimulated through the IgE receptor, and the homogenates were prepared and tested for phospholipase A2 activity on 1-stearoyl-2-[14C]arachidonyl-sn-3-phosphatidylcholine. The amount of activity in the homogenates was dependent on the concentration of secretagogue used to activate the cells. Under optimal conditions there was a 1.86 +/- 0.12-fold (mean +/- SEM, N = 44) increase in the activity found in homogenates of stimulated cells. Activity was present in homogenates prepared 30 sec after cell activation, was optimal between 5 and 10 min, and decreased later. In time course experiments the PLA2 activation preceded histamine release. The activation of the enzyme in the cell occurred in the presence of 10 microM EGTA in the extracellular medium, which completely inhibited release of arachidonic acid and histamine. However, the activity of the enzyme required Ca2+. The PLA2 activity in the homogenates and the extent of cell stimulation for histamine release were maximal at the same concentration of antigen, and both were blocked by the addition of a monovalent hapten. The enzyme in the homogenates was capable of cleaving arachidonic acid from different phospholipids. The production of lysophospholipids could play a critical role in histamine release from cells. These results demonstrate the activation of PLA2 enzyme in cellular homogenates during the secretory process.
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Garcia-Gil M, Siraganian RP. Phospholipase A2 stimulation during cell secretion in rat basophilic leukemia cells. The Journal of Immunology 1986. [DOI: 10.4049/jimmunol.136.1.259] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
Abstract
The bridging of IgE receptors on rat basophilic leukemia cells (RBL-2H3) results in a number of biochemical events that accompany histamine secretion. Prominent among these is the release of arachidonic acid from cellular phospholipids, which could be due to the activation of phospholipase enzymes. In the present experiments we studied the intracellular activation of phospholipase A2 (PLA2) during histamine release. RBL-2H3 cells were stimulated through the IgE receptor, and the homogenates were prepared and tested for phospholipase A2 activity on 1-stearoyl-2-[14C]arachidonyl-sn-3-phosphatidylcholine. The amount of activity in the homogenates was dependent on the concentration of secretagogue used to activate the cells. Under optimal conditions there was a 1.86 +/- 0.12-fold (mean +/- SEM, N = 44) increase in the activity found in homogenates of stimulated cells. Activity was present in homogenates prepared 30 sec after cell activation, was optimal between 5 and 10 min, and decreased later. In time course experiments the PLA2 activation preceded histamine release. The activation of the enzyme in the cell occurred in the presence of 10 microM EGTA in the extracellular medium, which completely inhibited release of arachidonic acid and histamine. However, the activity of the enzyme required Ca2+. The PLA2 activity in the homogenates and the extent of cell stimulation for histamine release were maximal at the same concentration of antigen, and both were blocked by the addition of a monovalent hapten. The enzyme in the homogenates was capable of cleaving arachidonic acid from different phospholipids. The production of lysophospholipids could play a critical role in histamine release from cells. These results demonstrate the activation of PLA2 enzyme in cellular homogenates during the secretory process.
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