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BACKGROUND: Episodic breathlessness is often accompanied by panic. A vicious cycle of breathlessness-panic-breathlessness leads to emergencies with severe breathlessness and/or fear of dying. However, the interaction between episodic breathlessness and panic is poorly understood. Thus, the aim is a better understanding of the interaction between panic and episodic breathlessness to develop appropriate support for patients suffering from this symptom. METHODS: Patients suffering from episodic breathlessness due to life-limiting diseases answered questions on the characteristics of episodic breathlessness and panic-spectrum psychopathology, including underlying mechanisms. Using the Patient Health Questionnaire and the Structured Clinical Interview for DSM-IV Diagnoses (SCID), patients were screened for panic disorder. An open-ended question captured the patients' descriptions of panic during breathlessness episodes. RESULTS: Forty-six patients [52% women, mean age =66 years; standard deviation (SD) 7.3 years] provided information: 61% suffered from panic during the entire breathlessness episode, 39% experienced panic in every episode, and 25% were diagnosed with panic disorder. Exploratory data analysis was conducted. Patients with high scores in breathlessness catastrophizing thoughts experienced more panic in a breathlessness episode (P<0.001) and considered themselves more panic than low-scorers (P=0.024). There was a significant indirect effect of episodic breathlessness intensity on the panic experienced in an episode, and this effect was mediated by catastrophizing thoughts regarding breathlessness (b=0.164; 95% CI: 0.105, 0.222). Patients described in the open-ended question experiencing only panic or breathlessness, or a combination of both. Some patients managed to differentiate panic from episodic breathlessness, and used strategies to avoid panic in an episode. CONCLUSIONS: Research on treatment options for episodic breathlessness should not only focus on panic in breathlessness episodes, but also on underlying mechanisms such as catastrophizing thoughts, as they aggravate the burden.
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Disnea , Miedo , Humanos , Femenino , Anciano , Masculino , Estudios TransversalesRESUMEN
CONTEXT: Episodic breathlessness is characterized by increased breathlessness intensity, and it is burdensome for patients. A vicious cycle of breathlessness-anxiety/panic-breathlessness leads to emergencies that can rarely be alleviated by drugs. Non-pharmacological interventions seem to be beneficial: Can a brief cognitive and behavioral intervention help patients to better manage episodic breathlessness? OBJECTIVES: To evaluate the feasibility, safety, acceptability, and potential effects of a brief cognitive and behavioral intervention for the management of episodic breathlessness. METHODS: Between February 2019 and February 2020, 49 patients with life-limiting diseases suffering from episodic breathlessness were enrolled in the single-arm phase II study. The baseline assessment was followed by the one- to two-hour intervention. In weeks two, four, and six after the intervention, the outcomes (main outcome of potential effects: mastery of breathlessness) were assessed, and in week six, a qualitative interview, and the final assessment took place. A mixed-methods approach was used to evaluate mainly the feasibility, including interviewing informal carers. RESULTS: 46/49 patients (24 female; 36 with COPD; mean age: 66.0 years) participated in the baseline assessment, 38 attended the intervention, 32 completed the final assessment, and 22 were interviewed. Study procedures and the intervention were feasible and mainly well accepted and patients did not experience burdens caused by it (28/32). In the interviews, patients described a positive change in their competencies in managing episodic breathlessness and feelings of anxiety during the episode. Mastery of breathlessness improved after the intervention. CONCLUSION: The brief cognitive and behavioral intervention and the study procedures are feasible, safe, and well accepted. We can describe a change for better management of episodic breathlessness in patients after the intervention, still, this needs to be evaluated in a Phase III trial for inclusion in the management of episodic breathlessness.
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Cuidadores , Disnea , Anciano , Ansiedad/terapia , Cuidadores/psicología , Cognición , Disnea/etiología , Femenino , Humanos , MasculinoRESUMEN
PURPOSE: To analyze the spectrum of uveitis at a German tertiary center. PATIENTS AND METHODS: A total of 474 consecutive patients with uveitis were classified according to the primary anatomic site of inflammation, examined for laterality of disease, and screened for etiologies. RESULTS: Out of the total, 253 patients (53%) had anterior uveitis, 90 patients (19%) had intermediate uveitis, 100 patients (21%) had posterior uveitis, and 31 patients (7%) had panuveitis. Fifty-six percent of the patients had bilateral involvement, predominantly in intermediate uveitis (ratio 4:1) and panuveitis (ratio 3.4:1). Regarding the etiology of all uveitis cases we found 17% infectious, 23% specific clinical entities, 20% associated with systemic disease (most commonly sarcoidosis with 11%), and 41% idiopathic uveitis. CONCLUSIONS: Anterior uveitis was the most common anatomic site of intraocular inflammation. Using a tailored approach, screening for systemic etiologies is recommended, since 20% of all patients had associated systemic diseases.
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PURPOSE: MET is a potential therapeutic target in lung cancer and both MET tyrosine kinase inhibitors and monoclonal antibodies have entered clinical trials. MET signaling can be activated by various mechanisms, including gene amplification. In this study, we aimed to investigate MET amplification status in adeno- and squamous cell carcinomas of the lung. We propose clearly defined amplification scores and provide epidemiologic data on MET amplification in lung cancer. EXPERIMENTAL DESIGN: We evaluated the prevalence of increased MET gene copy numbers in 693 treatment-naïve cancers by FISH, defined clear cutoff criteria, and correlated FISH results to MET IHC. RESULTS: Two thirds (67%) of lung cancers do not have gains in MET gene copy numbers, whereas 3% show a clear-cut high-level amplification (MET/centromer7 ratio ≥2.0 or average gene copy number per nucleus ≥6.0 or ≥10% of tumor cells containing ≥15 MET copies). The remaining cases can be subdivided into intermediate- (6%) and low-level gains (24%). Importantly, MET amplifications occur at equal frequencies in squamous and adenocarcinomas without or with EGFR or KRAS mutations. CONCLUSION: MET amplification is not a mutually exclusive genetic event in therapy-naïve non-small cell lung cancer. Our data suggest that it might be useful to determine MET amplification (i) before EGFR inhibitor treatment to identify possible primary resistance to anti-EGFR treatment, and (ii) to select cases that harbor KRAS mutations additionally to MET amplification and, thus, may not benefit from MET inhibition. Furthermore, our study provides comprehensive epidemiologic data for upcoming trials with various MET inhibitors.
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Adenocarcinoma/genética , Carcinoma de Células Escamosas/genética , Amplificación de Genes , Neoplasias Pulmonares/genética , Proteínas Proto-Oncogénicas c-met/genética , Adulto , Anciano , Anciano de 80 o más Años , Femenino , Dosificación de Gen , Humanos , Inmunohistoquímica , Hibridación Fluorescente in Situ , Masculino , Persona de Mediana EdadAsunto(s)
Biomarcadores/sangre , Pulmón/patología , Sarcoidosis/sangre , Uveítis/sangre , Adolescente , Adulto , Anciano , Anciano de 80 o más Años , Femenino , Humanos , Masculino , Persona de Mediana Edad , Sarcoidosis/diagnóstico , Sarcoidosis Pulmonar/sangre , Sarcoidosis Pulmonar/diagnóstico , Uveítis/complicaciones , Adulto JovenRESUMEN
Birt-Hogg-Dubé syndrome is a rare autosomal dominant condition caused by a germline mutation in the folliculin gene, which is characterized by skin fibrofolliculomas, multiple lung cysts and renal cancer. The clinical expression of the syndrome is highly variable, with recurrent pneumothoraces due to ruptured lung cysts in many cases. We report a patient with pneumomediastinum and cervico-facial emphysema after severe coughing without pneumothorax, skin lesions or renal tumour, but a striking family history of lung abnormalities.
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Síndrome de Birt-Hogg-Dubé/complicaciones , Síndrome de Birt-Hogg-Dubé/genética , Enfisema Mediastínico/complicaciones , Enfisema Mediastínico/genética , Síndrome de Birt-Hogg-Dubé/diagnóstico por imagen , Tos/complicaciones , Mutación del Sistema de Lectura , Humanos , Masculino , Enfisema Mediastínico/diagnóstico por imagen , Linaje , Fenotipo , Proteínas Proto-Oncogénicas/genética , Tomografía Computarizada por Rayos X , Proteínas Supresoras de Tumor/genética , Adulto JovenRESUMEN
We recently reported fibroblast growth factor receptor-type 1 (FGFR1) amplification to be associated with therapeutically tractable FGFR1 dependency in squamous cell lung cancer. This makes FGFR1 a novel target for directed therapy in these tumors. To reproducibly identify patients for clinical studies, we developed a standardized reading and evaluation strategy for FGFR1 fluorescence in-situ hybridization (FISH) and propose evaluation criteria, describe different patterns of low- and high-level amplifications and report on the prevalence of FGFR1 amplifications in pulmonary carcinomas. A total of 420 lung cancer patients including 307 squamous carcinomas, 100 adenocarcinomas of the lung and 13 carcinomas of other types were analyzed for FGFR1 amplification using a dual color FISH. We found heterogeneous and different patterns of gene copy numbers. FGFR1 amplifications were observed in 20% of pulmonary squamous carcinomas but not in adenocarcinomas. High-level amplification (as defined by an FGFR1/centromer 8 (CEN8) ratio ≥2.0, or average number of FGFR1 signals per tumor cell nucleus ≥6, or the percentage of tumor cells containing ≥15 FGFR1 signals or large clusters ≥10%) was detected at a frequency of 16% and low-level amplification (as defined by ≥5 FGFR1 signals in ≥50% of tumor cells) at a frequency of 4%. We conclude that FGFR1 amplification is one of the most frequent therapeutically tractable genetic lesions in pulmonary carcinomas. Standardized reporting of FGFR1 amplification in squamous carcinomas of the lung will become increasingly important to correlate therapeutic responses with FGFR1 inhibitors in clinical studies. Thus, our reading and evaluation strategy might serve as a basis for identifying patients for ongoing and upcoming clinical trials.
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Adenocarcinoma/genética , Carcinoma de Células Escamosas/genética , Amplificación de Genes , Hibridación Fluorescente in Situ , Neoplasias Pulmonares/genética , Receptor Tipo 1 de Factor de Crecimiento de Fibroblastos/genética , Adenocarcinoma/patología , Adenocarcinoma del Pulmón , Carcinoma de Células Escamosas/patología , Fijadores , Formaldehído , Dosificación de Gen , Predisposición Genética a la Enfermedad , Alemania , Humanos , Neoplasias Pulmonares/patología , Adhesión en Parafina , Fenotipo , Valor Predictivo de las Pruebas , Reproducibilidad de los Resultados , Fijación del TejidoAsunto(s)
Asma/complicaciones , Cardiomiopatía Dilatada/etiología , Disnea/etiología , Complicaciones Cardiovasculares del Embarazo/etiología , Adulto , Asma/diagnóstico , Cardiomiopatía Dilatada/diagnóstico , Cardiomiopatía Dilatada/tratamiento farmacológico , Fármacos Cardiovasculares/uso terapéutico , Cesárea , Diagnóstico Diferencial , Quimioterapia Combinada , Disnea/diagnóstico , Ecocardiografía Doppler en Color , Femenino , Humanos , Valor Predictivo de las Pruebas , Embarazo , Complicaciones Cardiovasculares del Embarazo/diagnóstico , Complicaciones Cardiovasculares del Embarazo/tratamiento farmacológico , Índice de Severidad de la Enfermedad , Resultado del TratamientoRESUMEN
Neurohumoral stimulation of Gq-coupled receptors has been proposed as a central mechanism in the pathogenesis of diabetic heart disease. The resulting contractile dysfunction is closely related to abnormal intracellular Ca(2+) handling with functional defects of the sarcoplasmic reticulum (SR). The present study was therefore designed to determine the role of G(q)-protein signaling via G(alpha)(11) and G(alpha)(q) in diabetes for the induction of functional and structural changes in the Ca(2+) release complex of the SR. An experimental type 1-diabetes was induced in wild type, G(alpha)(11) knockout, and G(alpha)(11/q)-knockout mice by injection of streptozotocin. Cardiac morphology and function was assessed in vivo by echocardiography. SR Ca(2+) leak was tested in vitro based on a (45)Ca(2+) assay and protein densities as well as gene expression of ryanodine receptor (RyR2), FKBP12.6, sorcin, and annexin A7 were analyzed by immunoblot and RT-PCR. In wild type animals 8 weeks of diabetes resulted in cardiac hypertrophy and SR Ca(2+) leak was increased. In addition, diabetic wild type animals showed reduced protein levels of FKBP12.6 and annexin A7. In G(alpha)(11)- and G(alpha)(11/q)-knockout animals, however, SR Ca(2+) release and cardiac phenotype remained unchanged upon induction of diabetes. Densities of the proteins that we presently analyzed were also unaltered in G(alpha)(11)-knockout mice. G(alpha)(11/q)-knockout animals even showed increased expression of sorcin and annexin A7. Thus, based on the present study we suggest a signaling pathway via the G(q)-proteins, G(alpha)(11) and G(alpha)(q), that could link increased neurohumoral stimulation in diabetes with defective RyR2 channel function by regulating protein expression of FKBP12.6, annexin A7, and sorcin.
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Calcio/metabolismo , Complicaciones de la Diabetes/metabolismo , Diabetes Mellitus Experimental/metabolismo , Subunidades alfa de la Proteína de Unión al GTP Gq-G11/metabolismo , Miocitos Cardíacos/metabolismo , Retículo Sarcoplasmático/metabolismo , Animales , Anexina A7/análisis , Cardiomegalia/etiología , Cardiomegalia/metabolismo , Diabetes Mellitus Experimental/patología , Cardiopatías/etiología , Cardiopatías/metabolismo , Ratones , Ratones Noqueados , Miocitos Cardíacos/patología , Proteínas/análisis , Canal Liberador de Calcio Receptor de Rianodina/análisis , Proteínas de Unión a Tacrolimus/análisisRESUMEN
Background Asymptomatic diabetic patients have a high incidence of clinically unrecognized left ventricular dysfunction with an abnormal cardiac response to exercise. We, therefore, examined subclinical defects in the contraction-relaxation cycle and intracellular Ca(2+) regulation in myocardium of asymptomatic type 2 diabetic patients. Methods Alterations in the dynamics of the intracellular Ca(2+) transient and contractility were recorded in right atrial myocardium of type 2 diabetic patients and non-diabetic control tissue loaded with fura-2. In order to gain an insight into mechanisms underlying the altered Ca(2+) handling in diabetic myocardium levels of mRNA, protein expression and phosphorylation of key proteins in sarcoplasmic Ca(2+) handling were determined. Results In isolated atrial trabeculae of diabetic myocardium the rise of systolic Ca(2+) was significantly prolonged, but relaxation of the Ca(2+) transient was unaltered compared to control tissue. Accordingly, the levels of expression of mRNA and protein of the Ca(2+) release channel (RyR2) of the sarcoplasmic reticulum were reduced by 68 and 22%, respectively. Endogenous phosphorylation of RyR2 by protein kinases C, however, was increased by 31% in diabetic myocardium, as assessed by the back-phosphorylation technique. Levels of expression of SERCA2 and phospholamban were unaltered between both groups. Conclusions Intracellular Ca(2+) release is prolonged in non-failing myocardium of type 2 diabetic patients and this may be primarily due to a decreased expression of RyR2. This defective Ca(2+) release may represent an early stage of ventricular dysfunction in type 2 diabetes and would favor the abnormal response to exercise frequently observed in asymptomatic diabetic patients.
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Calcio/metabolismo , Diabetes Mellitus/metabolismo , Miocardio/metabolismo , Miocardio/patología , Retículo Sarcoplasmático/metabolismo , Señalización del Calcio , Proteínas Quinasas Dependientes de AMP Cíclico/metabolismo , Diabetes Mellitus/fisiopatología , Femenino , Regulación Enzimológica de la Expresión Génica , Atrios Cardíacos/enzimología , Atrios Cardíacos/fisiopatología , Humanos , Contracción Isométrica , Masculino , Persona de Mediana Edad , Relajación Muscular , Miocardio/enzimología , Proteína Quinasa C/metabolismo , ARN Mensajero/genética , ARN Mensajero/metabolismo , Canal Liberador de Calcio Receptor de Rianodina/metabolismo , ATPasas Transportadoras de Calcio del Retículo Sarcoplásmico/metabolismoRESUMEN
Cardiac contraction is dependent on a rapid alteration of the intracellular Ca(2+) concentration, especially the Ca(2+) released during systole. In end-stage heart failure, cardiac contractility is depressed due to alterations in the structure and function of proteins or protein complexes. Over recent years, new insights have been obtained regarding the regulation of the intracellular Ca(2+) homeostasis and its pathophysiological alteration in end-stage heart failure. This review focuses on the mechanisms involved in the release of Ca(2+) from the sarcoplasmic reticulum (SR) during systole via the ryanodine receptors and the Ca(2+)-uptake into the SR by the sarcoplasmic reticulum Ca(2+)-ATPase (SERCA 2a). In addition, new therapeutic options will be introduced which may be of importance for the treatment of heart failure patients.
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Calcio/metabolismo , Insuficiencia Cardíaca/fisiopatología , Homeostasis/fisiología , Líquido Intracelular/fisiología , Disfunción Ventricular Izquierda/fisiopatología , Remodelación Ventricular/fisiología , ATPasas Transportadoras de Calcio/fisiología , Insuficiencia Cardíaca/terapia , Humanos , Contracción Miocárdica/fisiología , Canal Liberador de Calcio Receptor de Rianodina/fisiología , Retículo Sarcoplasmático/fisiología , ATPasas Transportadoras de Calcio del Retículo Sarcoplásmico , Sístole/fisiología , Disfunción Ventricular Izquierda/terapiaRESUMEN
In cardiac cells, phospholamban is a potent inhibitor of sarcoplasmic reticulum calcium (Ca(2+)) transport. Overexpression of mutant forms of phospholamban may result in beneficial or detrimental effects on intracellular Ca(2+) handling and cardiac systolic and diastolic function. Mutations in phospholamban have also been linked to human cardiomyopathies, providing important insights into the underlying disease mechanisms and the key role of phospholamban in myocardial excitation-contraction coupling. This Perspective discusses new advances in our understanding of the role of phospholamban in intracellular Ca(2+) handling and the development of human and murine cardiomyopathies.
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Proteínas de Unión al Calcio/fisiología , Calcio/metabolismo , Insuficiencia Cardíaca/metabolismo , Animales , Proteínas de Unión al Calcio/deficiencia , Proteínas de Unión al Calcio/genética , Insuficiencia Cardíaca/enzimología , Insuficiencia Cardíaca/genética , Insuficiencia Cardíaca/fisiopatología , HumanosRESUMEN
The cardiac SR Ca(2+)-ATPase (SERCA2a) regulates intracellular Ca(2+)-handling and thus, plays a crucial role in initiating cardiac contraction and relaxation. SERCA2a may be modulated through its accessory phosphoprotein phospholamban or by direct phosphorylation through Ca(2+)/calmodulin dependent protein kinase II (CaMK II). As an inhibitory component phospholamban, in its dephosphorylated form, inhibits the Ca(2+)-dependent SERCA2a function, while protein kinase A dependent phosphorylation of the phospho-residues serine-16 or Ca(2+)/calmodulin-dependent phosphorylation of threonine-17 relieves this inhibition. Recent evidence suggests that direct phosphorylation at residue serine-38 in SERCA2a activates enzyme function and enhances Ca(2+)-reuptake into the sarcoplasmic reticulum (SR). These effects that are mediated through phosphorylation result in an overall increased SR Ca(2+)-load and enhanced contractility. In human heart failure patients, as well as animal models with induced heart failure, these modulations are altered and may result in an attenuated SR Ca(2+)-storage and modulated contractility. It is also believed that abnormalities in Ca(2+)-cycling are responsible for blunting the frequency potentiation of contractile force in the failing human heart. Advanced gene expression and modulatory approaches have focused on enhancing SERCA2a function via overexpressing SERCA2a under physiological and pathophysiological conditions to restore cardiac function, cardiac energetics and survival rate.
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ATPasas Transportadoras de Calcio/metabolismo , Calcio/metabolismo , Contracción Miocárdica/fisiología , Miocardio/metabolismo , Retículo Sarcoplasmático/metabolismo , Animales , Proteínas de Unión al Calcio/metabolismo , ATPasas Transportadoras de Calcio/genética , Activación Enzimática , Regulación de la Expresión Génica , Terapia Genética/métodos , Insuficiencia Cardíaca/metabolismo , Humanos , Modelos Animales , Fosforilación , ATPasas Transportadoras de Calcio del Retículo SarcoplásmicoRESUMEN
OBJECTIVE: Phospholamban ablation or ectopic expression of SERCA1a in the heart results in significant increases in cardiac contractile parameters. The aim of the present study was to determine whether a combination of these two genetic manipulations may lead to further augmentation of cardiac function. METHODS: Transgenic mice with cardiac specific overexpression of SERCA1a were mated with phospholamban deficient mice to generate a model with SERCA1a overexpression in the phospholamban null background (SERCA1(OE)/PLB(KO)). The cardiac phenotype was characterized using quantitative immunoblotting, sarcoplasmic reticulum calcium uptake and single myocyte mechanics and calcium kinetics. RESULTS: Quantitative immunoblotting revealed an increase of 1.8-fold in total SERCA level, while SERCA2 was decreased to 50% of wild types. Isolated myocytes indicated increases in the maximal rates of contraction by 195 and 125%, the maximal rates of relaxation by 200 and 124%, while the time for 80% decay of the Ca(2+)-transient was decreased to 43 and 75%, in SERCA1(OE)/PLB(KO) hearts, compared to SERCA1a overexpressors and phospholamban knockouts, respectively. These mechanical alterations reflected parallel alterations in V(max) and EC(50) for Ca(2+) of the sarcoplasmic reticulum Ca(2+) transport system. Furthermore, there were no significant cardiac histological or pathological alterations, and the myocyte contractile parameters remained enhanced, up to 12 months of age. CONCLUSIONS: These findings suggest that a combination of SERCA1a overexpression and phospholamban ablation results in further enhancement of myocyte contractility over each individual alteration.
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Proteínas de Unión al Calcio/genética , ATPasas Transportadoras de Calcio/genética , Contracción Miocárdica , Miocardio/metabolismo , Animales , Calcio/metabolismo , ATPasas Transportadoras de Calcio/análisis , Tamaño de la Célula , Eliminación de Gen , Expresión Génica , Immunoblotting , Ratones , Ratones Noqueados , Ratones Transgénicos , Retículo Sarcoplasmático/metabolismo , ATPasas Transportadoras de Calcio del Retículo SarcoplásmicoRESUMEN
Human heart failure is characterized by distinct alterations in the intracellular homeostasis and key regulators of the sarcoplasmic reticulum Ca2+ sequestration mechanisms. Systolic peak Ca2+ is reduced, diastolic Ca2+ levels are increased and diastolic Ca2+ decay is prolonged. Recently specific changes in the expression, function and modulation of SR Ca2+-ATPase (SERCA) have been elucidated. As such, in a variety of studies SERCA expression appeared to be decreased in the failing human heart, although these findings have been discussed controversially depending on the studied tissue, especially with respect to the non-failing samples and regional variation in the obtained samples. However, consistent findings of a diminished Ca2+ dependent SERCA activation were found. Increasing evidence has been provided that one of the underlying mechanisms for a decreased activation of SERCA is its altered regulation. With respect to this, the modulations through phospholamban and Ca2+-dependent protein kinase II (CaMK II) play a detrimental role in regulating SERCA function. Phospholamban phosphorylation of SERCA at the serine-16 and threonine-17 site is diminished in human heart failure resulting in decreases in the apparent affinity for Ca2+ of the SR Ca2+ uptake rates. In contrast, activation of CaMK II leads to an increased maximal velocity of SR Ca2+ sequestration that may enhance SR Ca2+-load. Additional regulation has been recently elucidated by changes in the apparent coupling ratio of Ca2+ transported per ATP hydrolysed. This review summarizes recent advances in the understanding how SERCA is modulated under physiological and pathophysiological conditions.
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ATPasas Transportadoras de Calcio/metabolismo , Gasto Cardíaco Bajo/enzimología , Miocardio/enzimología , Animales , Proteínas de Unión al Calcio/metabolismo , Humanos , Fosforilación , ATPasas Transportadoras de Calcio del Retículo SarcoplásmicoRESUMEN
OBJECTIVE: Impaired myocyte Ca2+ handling is a common characteristic of failing hearts and increases in calcineurin activity, a Ca2+-sensitive phosphatase, have been implicated in heart failure phenotype. Transgenic mice with cardiac-specific expression of an active form of calcineurin display depressed function, hypertrophy and heart failure. We examined whether defects in cardiomyocyte Ca2+ handling properties contribute to the impaired cardiac function in calcineurin transgenic mice. METHODS: The levels of SR Ca2+ handling proteins, SR Ca2+ transport function and cardiomyocyte mechanics, as well as Ca2+ kinetics were examined in mice overexpressing a constitutively active form of calcineurin. RESULTS: Transgenic expression of activated calcineurin catalytic subunit resulted in significant protein increases (66%) in SERCA2 and decreases (35%) in phospholamban, as well as enhanced (approximately 80%) phospholamban phosphorylation. These alterations in the SR Ca2+-transport proteins resulted in increased V(max) and Ca2+-affinity of SERCA2. The myofibrillar Mg-ATPase activity was also significantly increased at pCa>6.0. The enhanced SR Ca2+ handling and Mg-ATPase activity reflected significant elevation in myocyte contractile parameters (3-fold), Ca2+ transient amplitude (1.5-fold) and the rate of Ca2+ signal decay (2-fold). In contrast, in vivo cardiac function assessed by echocardiography, indicated severely depressed contractility in calcineurin hearts. The apparent disparity in contractile properties between the cellular and multicellular preparations may be partially due to tissue remodeling, including interstitial fibrosis and a marked reduction (45%), dephosphorylation (81%) and redistribution of the gap junctional protein connexin-43, which could compromise intercellular communication. CONCLUSION: Despite enhanced SR Ca2+ handling and contractility in myocytes, pathological remodeling and defects in intercellular coupling may underlie contractile dysfunction of the calcineurin hearts.