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Purinergic signaling is a crucial determinant in the regulation of pulmonary vascular physiology and presents a promising avenue for addressing lung diseases. This intricate signaling system encompasses two primary receptor classes: P1 and P2 receptors. P1 receptors selectively bind adenosine, while P2 receptors exhibit an affinity for ATP, ADP, UTP, and UDP. Functionally, P1 receptors are associated with vasodilation, while P2 receptors mediate vasoconstriction, particularly in basally relaxed vessels, through modulation of intracellular Ca2+ levels. The P2X subtype receptors facilitate extracellular Ca2+ influx, while the P2Y subtype receptors are linked to endoplasmic reticulum Ca2+ release. Notably, the primary receptor responsible for ATP-induced vasoconstriction is P2X1, with α,ß-meATP and UDP being identified as potent vasoconstrictor agonists. Interestingly, ATP has been shown to induce endothelium-dependent vasodilation in pre-constricted vessels, associated with nitric oxide (NO) release. In the context of P1 receptors, adenosine stimulation of pulmonary vessels has been unequivocally demonstrated to induce vasodilation, with a clear dependency on the A2B receptor, as evidenced in studies involving guinea pigs and rats. Importantly, evidence strongly suggests that this vasodilation occurs independently of endothelium-mediated mechanisms. Furthermore, studies have revealed variations in the expression of purinergic receptors across different vessel sizes, with reports indicating notably higher expression of P2Y1, P2Y2, and P2Y4 receptors in small pulmonary arteries. While the existing evidence in this area is still emerging, it underscores the urgent need for a comprehensive examination of the specific characteristics of purinergic signaling in the regulation of pulmonary vascular tone, particularly focusing on the disparities observed across different intrapulmonary vessel sizes. Consequently, this review aims to meticulously explore the current evidence regarding the role of purinergic signaling in pulmonary vascular tone regulation, with a specific emphasis on the variations observed in intrapulmonary vessel sizes. This endeavor is critical, as purinergic signaling holds substantial promise in the modulation of vascular tone and in the proactive prevention and treatment of pulmonary vascular diseases.
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Cardiovascular diseases (CVDs) are the leading cause of morbidity and mortality worldwide. Epidemiological studies indicate that pre-menopausal women are more protected against the development of CVDs compared to men of the same age. This effect is attributed to the action/effects of sex steroid hormones on the cardiovascular system. In this context, estrogen modulates cardiovascular function in physiological and pathological conditions, being one of the main physiological cardioprotective agents. Here we describe the common pathways and mechanisms by which estrogens modulate the retrograde and anterograde communication between the nucleus and mitochondria, highlighting the role of genomic and non-genomic pathways mediated by estrogen receptors. Additionally, we discuss the presumable role of bromodomain-containing protein 4 (BRD4) in enhancing mitochondrial biogenesis and function in different CVD models and how this protein could act as a master regulator of estrogen protective activity. Altogether, this review focuses on estrogenic control in gene expression and molecular pathways, how this activity governs nucleus-mitochondria communication, and its projection for a future generation of strategies in CVDs treatment.
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BACKGROUND: Acute respiratory distress syndrome (ARDS) is a severe form of respiratory failure characterized by altered lung mechanics and poor oxygenation. Bronchial hyperresponsiveness has been reported in ARDS survivors and animal models of acute lung injury. Whether this hyperreactivity occurs at the small airways or not is unknown. OBJECTIVE: To determine ex-vivo small airway reactivity in a rat model of acute lung injury (ALI) by hydrochloric acid (HCl) instillation. METHODS: Twelve anesthetized rats were connected to mechanical ventilation for 4-hour, and randomly allocated to either ALI group (HCl intratracheal instillation; n=6) or Sham (intratracheal instillation of 0.9% NaCl; n=6). Oxygenation was assessed by arterial blood gases. After euthanasia, tissue samples from the right lung were harvested for histologic analysis and wet-dry weight ratio assessment. Precision cut lung slice technique (100-200 µm diameter) was applied in the left lung to evaluate ex vivo small airway constriction in response to histamine and carbachol stimulation, using phase-contrast video microscopy. RESULTS: Rats from the ALI group exhibited hypoxemia, worse histologic lung injury, and increased lung wet-dry weight ratio as compared with the sham group. The bronchoconstrictor responsiveness was significantly higher in the ALI group, both for carbachol (maximal contraction of 84.5±2.5% versus 61.4±4.2% in the Sham group, P<0.05), and for histamine (maximal contraction of 78.6±5.3% versus 49.6±5.3% in the Sham group, P<0.05). CONCLUSION: In an animal model of acute lung injury secondary to HCL instillation, small airway hyperresponsiveness to carbachol and histamine is present. These results may provide further insight into the pathophysiology of ARDS.
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The right and left ventricles have traditionally been studied as individual entities. Furthermore, modifications found in diseased left ventricles are assumed to influence on right ventricle alterations, but the connection is poorly understood. In this review, we describe the differences between ventricles under physiological and pathological conditions. Understanding the mechanisms that differentiate both ventricles would facilitate a more effective use of therapeutics and broaden our knowledge of right ventricle (RV) dysfunction. RV failure is the strongest predictor of mortality in pulmonary arterial hypertension, but at present, there are no definitive therapies directly targeting RV failure. We further explore the current state of drugs and molecules that improve RV failure in experimental therapeutics and clinical trials to treat pulmonary arterial hypertension and provide evidence of their potential benefits in heart failure.
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Ventrículos Cardíacos/fisiopatología , Hipertensión Arterial Pulmonar/fisiopatología , Disfunción Ventricular Derecha/fisiopatología , HumanosRESUMEN
BACKGROUND: Amyloid-ß peptide (Aß) deposition in Alzheimer's disease (AD) is due to an imbalance in its production/clearance rate. Aß is transported across the blood-brain barrier by LRP1 and P-gp as efflux transporters and RAGE as influx transporter. Vitamin D deficit and polymorphisms of the vitamin D receptor (VDR) gene are associated with high prevalence of mild cognitive impairment (MCI) and AD. Further, vitamin D promotes the expression of LRP1 and P-gp in AD-animal model brains. OBJECTIVE: To associate VDR polymorphisms Apa I (rs7975232), Taq I (rs731236), and Fok I (rs2228570) with the risk of developing MCI in a Chilean population, and to evaluate the relationship of these polymorphisms to the expression of VDR and Aß-transporters in peripheral blood mononuclear cells (PBMCs). METHODS: VDR polymorphisms Apa I, Taq I, and Fok I were determined in 128 healthy controls (HC) and 66 MCI patients. mRNA levels of VDR and Aß-transporters were evaluated in subgroups by qPCR. RESULTS: Alleles A of Apa I and C of Taq I were associated with a lower risk of MCI. HC with the Apa I AA genotype had higher mRNA levels of P-gp and LRP1, while the expression of VDR and RAGE were higher in MCI patients and HC. For Fok I, the TC genotype was associated with lower expression levels of Aß-transporters in both groups. CONCLUSION: We propose that the response to vitamin D treatment will depend on VDR polymorphisms, being more efficient in carriers of protective alleles of Apa I polymorphism.
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Péptidos beta-Amiloides/biosíntesis , Péptidos beta-Amiloides/genética , Disfunción Cognitiva/genética , Disfunción Cognitiva/metabolismo , Polimorfismo de Nucleótido Simple/genética , Receptores de Calcitriol/genética , Anciano , Chile/epidemiología , Disfunción Cognitiva/epidemiología , Estudios de Cohortes , Femenino , Expresión Génica , Humanos , Masculino , Proteínas de Transporte de Membrana/genética , Proteínas de Transporte de Membrana/metabolismo , Factores de Riesgo , Polimerasa Taq/genética , Polimerasa Taq/metabolismo , Factores de Transcripción/genética , Factores de Transcripción/metabolismoRESUMEN
Clara cells are the main airway secretory cells able to regenerate epithelium in the distal airways through transdifferentiating into goblet cells, a process under negative regulation of the Notch pathway. Pneumocystis is a highly prevalent fungus in humans occurring between 2 and 5 months of age, a period when airways are still developing and respiratory morbidity typically increases. Pneumocystis induces mucus hyperproduction in immunocompetent host airways and whether it can stimulate Clara cells is unknown. Markers of Clara cell secretion and Notch1 activation were investigated in lungs of immunocompetent rats at 40, 60, and 80 days of age during Pneumocystis primary infection with and without Valproic acid (VPA), a Notch inducer. The proportion of rats expressing mucin increased in Pneumocystis-infected rats respect to controls at 60 and 80 days of age. Frequency of distal airways Clara cells was maintained while mRNA levels for the mucin-encoding genes Muc5B and Muc5ac in lung homogenates increased 1.9 and 3.9 times at 60 days of infection (P. = 0.1609 and P. = 0.0001, respectively) and protein levels of the Clara cell marker CC10 decreased in the Pneumocystis-infected rats at 60 and 80 days of age (P. = 0.0118 & P. = 0.0388). CC10 and Muc5b co-localized in distal airway epithelium of Pneumocystis-infected rats at day 60. Co-localization of Muc5b and Ki67 as marker of mitosis in distal airways was not observed suggesting that Muc5b production by Clara cells was independent of mitosis. Notch levels remained similar and no transnucleation of activated Notch associated to Pneumocystis infection was detected. Unexpectedly, mucus was greatly increased at day 80 in Pneumocystis-infected rats receiving VPA suggesting that a Notch-independent mechanism was triggered. Overall, data suggests a Clara to goblet cell transdifferentiation mechanism induced by Pneumocystis and independent of Notch.
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Pulmón/metabolismo , Pulmón/microbiología , Mucina 5AC/biosíntesis , Mucina 5B/biosíntesis , Infecciones por Pneumocystis/metabolismo , Infecciones por Pneumocystis/microbiología , Pneumocystis/patogenicidad , Receptores Notch/metabolismo , Animales , Transdiferenciación Celular/efectos de los fármacos , Células Epiteliales/efectos de los fármacos , Células Epiteliales/metabolismo , Femenino , Antígeno Ki-67/metabolismo , Mitosis/efectos de los fármacos , Mucina 5AC/genética , Mucina 5AC/metabolismo , Mucina 5B/genética , Mucina 5B/metabolismo , Pneumocystis/efectos de los fármacos , Infecciones por Pneumocystis/patología , ARN Mensajero/genética , ARN Mensajero/metabolismo , Ratas Sprague-Dawley , Transducción de Señal , Uteroglobina/metabolismo , Ácido Valproico/farmacologíaRESUMEN
KEY POINTS: We investigated the excitation-contraction coupling mechanisms in small pulmonary veins (SPVs) in rat precision-cut lung slices. We found that SPVs contract strongly and reversibly in response to extracellular ATP and other vasoconstrictors, including angiotensin-II and endothelin-1. ATP-induced vasoconstriction in SPVs was associated with the stimulation of purinergic P2Y2 receptors in vascular smooth muscle cell, activation of phospholipase C-ß and the generation of intracellular Ca2+ oscillations mediated by cyclic Ca2+ release events via the inositol 1,4,5-trisphosphate receptor. Active constriction of SPVs may play an important role in the development of pulmonary hypertension and pulmonary oedema. ABSTRACT: The small pulmonary veins (SPVs) may play a role in the development of pulmonary hypertension and pulmonary oedema via active changes in SPV diameter, mediated by vascular smooth muscle cell (VSMC) contraction. However, the excitation-contraction coupling mechanisms during vasoconstrictor stimulation remain poorly understood in these veins. We used rat precision-cut lung slices and phase-contrast and confocal microscopy to investigate dynamic changes in SPV cross-sectional luminal area and intracellular Ca2+ signalling in their VSMCs. We found that the SPV (â¼150 µm in diameter) contract strongly in response to extracellular ATP and other vasoconstrictors, including angiotensin-II and endothelin-1. ATP-induced SPV contraction was fast, concentration-dependent, completely reversible upon ATP washout, and inhibited by purinergic receptor antagonists suramin and AR-C118925 but not by MRS2179. Immunofluorescence showed purinergic P2Y2 receptors expressed in SPV VSMCs. ATP-induced SPV contraction was inhibited by phospholipase Cß inhibitor U73122 and accompanied by intracellular Ca2+ oscillations in the VSMCs. These Ca2+ oscillations and SPV contraction were inhibited by the inositol 1,4,5-trisphosphate receptor inhibitor 2-APB but not by ryanodine. The results of the present study suggest that ATP-induced vasoconstriction in SPVs is associated with the activation of purinergic P2Y2 receptors in VSMCs and the generation of Ca2+ oscillations.
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Calcio/fisiología , Contracción Muscular , Miocitos del Músculo Liso/fisiología , Venas Pulmonares/fisiología , Receptores Purinérgicos P2Y2/metabolismo , Vasoconstricción , Adenosina Trifosfato/metabolismo , Animales , Células Cultivadas , Estudios Transversales , Acoplamiento Excitación-Contracción , Receptores de Inositol 1,4,5-Trifosfato/metabolismo , Miocitos del Músculo Liso/citología , Fosfolipasa C beta/metabolismo , Venas Pulmonares/citología , RatasRESUMEN
We have proposed that a common biological mechanism deregulated in opposite directions might explain the inverse epidemiological association observed between Alzheimer's disease (AD) and cancer. Accordingly, we showed that lymphocytes from AD patients have an increased susceptibility, whereas those from survivors of a skin cancer, an increased resistance to oxidative death induced by hydrogen peroxide (H2O2), compared to healthy controls (HC). We investigated the susceptibility to H2O2-induced death of lymphocytes in survivors of any type of cancer and in cancer survivors who later developed AD (Ca&AD). We also explored the involvement of Poly [ADP-ribose] polymerase-1 (PARP-1) and p53 pathways in the process, since both are involved in the increased susceptibility to death of AD lymphocytes. Lymphocytes from 11 cancer and 13 Ca&AD patients, and 12 HC were submitted to increasing concentrations of H2O2 for 20 h. Cell death was determined by flow cytometry, in the presence or absence of PARP-1 inhibition (3-aminobenzamide, 3-ABA), or p53 inhibition (pifithrin-α) or stabilization (Nut-3). PARP-1 and p53 mRNA levels were determined by Real-Time PCR. Lymphocytes from cancer and Ca&AD patients showed increased survival compared to HC, without differences between them, opposite to the increased susceptibility to death previously shown in AD. PARP-1 inhibition provided marked protection from H2O2-induced death in the two groups of patients, significantly greater than in HC. Pharmacological inhibition of p53 increased lymphocyte survival in Ca&AD patients, contrary to the effect previously reported in HC and AD. PARP-1 and p53 mRNA levels were elevated in Ca&AD lymphocytes compared with controls. In all, these results show that cancer imprints an increased resistance to H2O2-induced death in lymphocytes that persists after AD development, and is dependent on both PARP-1 and p53. p53 inhibition showed a differential role in cancer and Ca&AD compared to HC and AD lymphocytes, that could explain the inverse susceptibility to oxidative death in cancer and AD. These results are in agreement with the hypothesis of a common biological mechanism in AD and cancer. The similar cell death susceptibility and cell death pattern observed in cancer and Ca&AD lymphocytes suggests that cancer history leaves long term effects on lymphocyte cell death susceptibility.
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BACKGROUND: Mild cognitive impairment (MCI) has an increased rate of progression to dementia. Alterations of some metabolic factors, such as deficiency of vitamin D, are a risk factor for cognitive deterioration. Vitamin D is involved in the clearance of ß-amyloid (Aß) from the brain. We have reported that lymphocytes from Alzheimer's disease (AD) patients have an increased susceptibility to oxidative death by H2O2 exposure, but currently it is unknown if this characteristic is modifiable in vivo. OBJECTIVE: To determine if correction of low vitamin D levels protects lymphocytes from oxidative death and increases Aß1-40 plasma levels in MCI and very early AD (VEAD) patients. METHOD: Sixteen MCI, 11 VEAD and 25 healthy control (HC) voluntaries were evaluated with the Clinical Dementia Rating (CDR), Montreal Cognitive assessment (MoCA), and Memory Index score (MIS). Lymphocyte death was measured by flow cytometry after 20h exposure to H2O2. In patients with low levels of vitamin D -11 MCI, 9 VEAD and 20 HC- lymphocyte H2O2-death, plasma Aß1-40 levels and cognitive status were evaluated pre- and post-vitamin D supplementation for 6 months. RESULTS: Lymphocytes from MCI and VEAD patients showed increased susceptibility to oxidative death at study entry. In MCI, but not VEAD patients, lymphocyte susceptibility to death and Aß1-40 levels plasma levels improved after 6 months of vitamin D supplementation. In addition, cognitive status on follow-up (18 months) improved in MCI patients after vitamin D supplementation. CONCLUSION: Vitamin D supplementation may be beneficial in MCI. The lack of effect in VEAD may be due to a more advanced stage or different characteristics of the neurodegenerative process.
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Enfermedad de Alzheimer/tratamiento farmacológico , Péptidos beta-Amiloides/sangre , Colecalciferol/uso terapéutico , Disfunción Cognitiva/tratamiento farmacológico , Linfocitos/efectos de los fármacos , Fármacos Neuroprotectores/uso terapéutico , Fragmentos de Péptidos/sangre , Anciano , Anciano de 80 o más Años , Enfermedad de Alzheimer/sangre , Biomarcadores/sangre , Muerte Celular/efectos de los fármacos , Muerte Celular/fisiología , Supervivencia Celular/efectos de los fármacos , Células Cultivadas , Cognición/efectos de los fármacos , Disfunción Cognitiva/sangre , Femenino , Estudios de Seguimiento , Humanos , Peróxido de Hidrógeno/toxicidad , Masculino , Persona de Mediana Edad , Nootrópicos/uso terapéutico , Estrés Oxidativo/efectos de los fármacos , Estrés Oxidativo/fisiología , Resultado del TratamientoRESUMEN
Mild cognitive impairment (MCI) is a clinically detectable initial stage of cognitive deterioration with a high conversion rate to dementia. There is increasing evidence that some of the cerebral alterations present in Alzheimer type dementia can be found in peripheral tissues. We have previously shown that lymphocytes from Alzheimer's disease (AD) patients have increased susceptibility to hydrogen peroxide (H2O2)-induced death that depends on dementia severity. We here investigated whether lymphocytes from MCI patients show increased vulnerability to death, and explored the involvement of Poly [ADP-ribose] polymerase (PARP-1) and p53 in the regulation of this process. Lymphocytes from 16 MCI and 10 AD patients, and 15 healthy controls (HCs) were submitted to increasing concentrations of H2O2 for 20 h. Cell death was determined by flow cytometry, in the presence or absence of PARP-1 inhibitors (3-aminobenzamide (3-ABA) or Nicotinamide (NAM)), or the p53 inhibitor (nutlin-3) or stabilizer (pifithrin-α). PARP-1 and p53 mRNA levels were determined by quantitative PCR (qPCR). Lymphocytes from MCI patients showed increased susceptibility to death, attaining intermediate values between AD and controls. PARP inhibitors -3-ABA and NAM- markedly protected from H2O2-induced death, making the difference between MCI and controls disappear, but not the difference between AD and controls. PARP-1 mRNA expression was increased in MCI lymphocytes. Modulation of p53 with Nutlin-3 or pifithrin-α did not modify the H2O2-induced death of lymphocytes from MCI or AD patients, but augmented the death in control lymphocytes attaining levels similar to MCI and AD. Accordingly, p53 mRNA expression was increased in AD and MCI lymphocytes compared to controls. In all, these results show that increased oxidative death is present in lymphocytes at the MCI stage. PARP-1 has a preponderant role, with complete death protection achieved with PARP inhibition in MCI lymphocytes, but not in AD, suggesting that PARP-1 might have a protective role. In addition, deregulations of the p53 pathway seem to contribute to the H2O2-induced death in MCI and AD lymphocytes, which show increased p53 expression. The results showing a prominent protective role of PARP inhibitors opens the door to study the use of these agents to prevent oxidative death in MCI patients.
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Blastic plasmacytoid dendritic cell neoplasm (BPDCN) is a rare, clinically aggressive hematologic malignancy that most commonly manifests as cutaneous lesions with or without bone marrow involvement and leukemic dissemination. The demonstration of tumor cells with the characteristic immunophenotype with expression of CD56, generally CD4 and dendritic cell antigens (CD123, cyTCL-1, HLA-DR), in the absence of myeloid or lymphoid lineage markers is required for the diagnosis. Responses to chemotherapy are initially satisfactory, with frequent systemic and central nervous system relapses. We report a 24 year-old male with BPDCN, initially diagnosed and treated as non-Hodgkin CD4+ T-cell lymphoma, with initial complete remission who evolved with early central nervous system relapse. A second attempt of chemotherapy failed and the patient died two months later.
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Neoplasias del Sistema Nervioso Central/secundario , Células Dendríticas/patología , Neoplasias Hematológicas/patología , Protocolos de Quimioterapia Combinada Antineoplásica/uso terapéutico , Progresión de la Enfermedad , Resultado Fatal , Neoplasias Hematológicas/tratamiento farmacológico , Humanos , Inmunofenotipificación , Masculino , Inducción de Remisión , Adulto JovenRESUMEN
Blastic plasmacytoid dendritic cell neoplasm (BPDCN) is a rare, clinically aggressive hematologic malignancy that most commonly manifests as cutaneous lesions with or without bone marrow involvement and leukemic dissemination. The demonstration of tumor cells with the characteristic immunophenotype with expression of CD56, generally CD4 and dendritic cell antigens (CD123, cyTCL-1, HLA-DR), in the absence of myeloid or lymphoid lineage markers is required for the diagnosis. Responses to chemotherapy are initially satisfactory, with frequent systemic and central nervous system relapses. We report a 24 year-old male with BPDCN, initially diagnosed and treated as non-Hodgkin CD4+ T-cell lymphoma, with initial complete remission who evolved with early central nervous system relapse. A second attempt of chemotherapy failed and the patient died two months later.
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Humanos , Masculino , Adulto Joven , Células Dendríticas/patología , Neoplasias del Sistema Nervioso Central/secundario , Neoplasias Hematológicas/patología , Inducción de Remisión , Protocolos de Quimioterapia Combinada Antineoplásica/uso terapéutico , Inmunofenotipificación , Resultado Fatal , Progresión de la Enfermedad , Neoplasias Hematológicas/tratamiento farmacológicoRESUMEN
Fas ligation via the ligand FasL activates the caspase-8/caspase-3-dependent extrinsic death pathway. In so-called type II cells, an additional mechanism involving tBid-mediated caspase-9 activation is required to efficiently trigger cell death. Other pathways linking FasL-Fas interaction to activation of the intrinsic cell death pathway remain unknown. However, ATP release and subsequent activation of purinergic P2X(7) receptors (P2X(7)Rs) favors cell death in some cells. Here, we evaluated the possibility that ATP release downstream of caspase-8 via pannexin1 hemichannels (Panx1 HCs) and subsequent activation of P2X(7)Rs participate in FasL-stimulated cell death. Indeed, upon FasL stimulation, ATP was released from Jurkat cells in a time- and caspase-8-dependent manner. Fas and Panx1 HCs colocalized and inhibition of the latter, but not connexin hemichannels, reduced FasL-induced ATP release. Extracellular apyrase, which hydrolyzes ATP, reduced FasL-induced death. Also, oxidized-ATP or Brilliant Blue G, two P2X(7)R blockers, reduced FasL-induced caspase-9 activation and cell death. These results represent the first evidence indicating that the two death receptors, Fas and P2X(7)R connect functionally via caspase-8 and Panx1 HC-mediated ATP release to promote caspase-9/caspase-3-dependent cell death in lymphoid cells. Thus, a hitherto unsuspected route was uncovered connecting the extrinsic to the intrinsic pathway to amplify death signals emanating from the Fas receptor in type II cells.
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Adenosina Trifosfato/fisiología , Apoptosis , Caspasa 8/fisiología , Proteína Ligando Fas/fisiología , Receptores Purinérgicos P2X7/fisiología , Adenosina Trifosfato/análogos & derivados , Adenosina Trifosfato/farmacología , Apirasa/fisiología , Caspasa 3/fisiología , Caspasa 9/fisiología , Conexinas/fisiología , Humanos , Células Jurkat , Proteínas del Tejido Nervioso/fisiología , Antagonistas del Receptor Purinérgico P2X/farmacología , Colorantes de Rosanilina/farmacología , Transducción de Señal/efectos de los fármacos , Transducción de Señal/fisiología , Receptor fas/fisiologíaRESUMEN
Thy-1, an abundant mammalian glycoprotein, interacts with αvß3 integrin and syndecan-4 in astrocytes and thus triggers signaling events that involve RhoA and its effector p160ROCK, thereby increasing astrocyte adhesion to the extracellular matrix. The signaling cascade includes calcium-dependent activation of protein kinase Cα upstream of Rho; however, what causes the intracellular calcium transients required to promote adhesion remains unclear. Purinergic P2X7 receptors are important for astrocyte function and form large non-selective cation pores upon binding to their ligand, ATP. Thus, we evaluated whether the intracellular calcium required for Thy-1-induced cell adhesion stems from influx mediated by ATP-activated P2X7 receptors. Results show that adhesion induced by the fusion protein Thy-1-Fc was preceded by both ATP release and sustained intracellular calcium elevation. Elimination of extracellular ATP with Apyrase, chelation of extracellular calcium with EGTA, or inhibition of P2X7 with oxidized ATP, all individually blocked intracellular calcium increase and Thy-1-stimulated adhesion. Moreover, Thy-1 mutated in the integrin-binding site did not trigger ATP release, and silencing of P2X7 with specific siRNA blocked Thy-1-induced adhesion. This study is the first to demonstrate a functional link between αvß3 integrin and P2X7 receptors, and to reveal an important, hitherto unanticipated, role for P2X7 in calcium-dependent signaling required for Thy-1-stimulated astrocyte adhesion.
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Adenosina Trifosfato/metabolismo , Adhesiones Focales/metabolismo , Integrinas/metabolismo , Receptores Purinérgicos P2X7/metabolismo , Antígenos Thy-1/metabolismo , Animales , Astrocitos/metabolismo , Western Blotting , Calcio/metabolismo , Línea Celular , Técnica del Anticuerpo Fluorescente Indirecta , Integrinas/genética , Ratas , Receptores Purinérgicos P2X7/genética , Antígenos Thy-1/genéticaRESUMEN
Potassium channels (K(+) channels) are members of one of the largest and most diverse families of membrane proteins, widely described from bacteria to humans. Their functions include voltage-membrane potential maintenance, pH and cell volume regulation, excitability, organogenesis and cell death. K(+) channels are involved in sensing and responding to environmental changes such as acidification, O(2) pressure, osmolarity, and ionic concentration. Trypanosoma cruzi is a parasitic protozoan, causative agent of Chagas disease (American trypanosomiasis) an endemic pathology in Latin America, where up 200,000 new cases are reported annually. In protozoan parasites, the presence of K(+) channels has been suggested, but functional direct evidence supporting this hypothesis is limited, mainly due to the difficulty of employing conventional electrophysiological methods to intact parasites. In T. cruzi, K(+) conductive pathways are thought to contribute in the regulatory volume decrease observed under hypoosmotic stress, the steady state pH and the compensatory response to extracellular acidification and the maintenance of plasma membrane potential. In this work we describe the isolation of plasma membrane enriched fractions from T. cruzi epimastigotes, their reconstitution into giant liposomes and the first functional characterization by patch-clamp of K(+) conductive pathways in protozoan parasites.
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Canales de Potasio/fisiología , Proteínas Protozoarias/fisiología , Transducción de Señal/fisiología , Trypanosoma cruzi/fisiología , Animales , Cationes Bivalentes/farmacología , Cationes Monovalentes/farmacología , Membrana Celular/fisiología , Membrana Celular/ultraestructura , Enfermedad de Chagas/parasitología , Fenómenos Electrofisiológicos , Humanos , Canales Iónicos/fisiología , Liposomas , Potenciales de la Membrana/efectos de los fármacos , Potenciales de la Membrana/fisiología , Microscopía Electrónica , Técnicas de Placa-Clamp , Cloruro de Potasio/farmacología , Trypanosoma cruzi/metabolismoRESUMEN
Apoptosis is a programmed form of cell death with well-defined morphological traits that are often associated with activation of caspases. More recently evidence has become available demonstrating that upon caspase inhibition alternative programs of cell death are executed, including ones with features characteristic of necrosis. These findings have changed our view of necrosis as a passive and essentially accidental form of cell death to that of an active, regulated and controllable process. Also necrosis has now been observed in parallel with, rather than as an alternative pathway to, apoptosis. Thus, cell death responses are extremely flexible despite being programmed. In this review, some of the hallmarks of different programmed cell death modes have been highlighted before focusing the discussion on necrosis. Obligatory events associated with this form of cell death include uncompensated cell swelling and related changes at the plasma membrane. In this context, representatives of the transient receptor channel family and their regulation are discussed. Also mechanisms that lead to execution of the necrotic cell death program are highlighted. Emphasis is laid on summarizing our understanding of events that permit switching between cell death modes and how they connect to necrosis. Finally, potential implications for the treatment of some disease states are mentioned.
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Necrosis/metabolismo , Animales , Apoptosis , Autofagia , Caspasas/metabolismo , Ceramidas/metabolismo , Humanos , Membranas Intracelulares/metabolismo , Modelos Biológicos , Canales Catiónicos TRPC/metabolismoRESUMEN
In lymphocytes, Fas activation leads to both apoptosis and necrosis, whereby the latter form of cell death is linked to delayed production of endogenous ceramide and is mimicked by exogenous administration of long- and short-chain ceramides. Here molecular events associated with noncanonical necrotic cell death downstream of ceramide were investigated in A20 B lymphoma and Jurkat T cells. Cell-permeable, C6-ceramide (C6), but not dihydro-C6-ceramide (DH-C6), induced necrosis in a time- and dose-dependent fashion. Rapid formation of reactive oxygen species (ROS) within 30 min of C6 addition detected by a dihydrorhodamine fluorescence assay, as well as by electron spin resonance, was accompanied by loss of mitochondrial membrane potential. The presence of N-acetylcysteine or ROS scavengers like Tiron, but not Trolox, attenuated ceramide-induced necrosis. Alternatively, adenovirus-mediated expression of catalase in A20 cells also attenuated cell necrosis but not apoptosis. Necrotic cell death observed following C6 exposure was associated with a pronounced decrease in ATP levels and Tiron significantly delayed ATP depletion in both A20 and Jurkat cells. Thus, apoptotic and necrotic death induced by ceramide in lymphocytes occurs via distinct mechanisms. Furthermore, ceramide-induced necrotic cell death is linked here to loss of mitochondrial membrane potential, production of ROS, and intracellular ATP depletion.
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Adenosina Trifosfato/metabolismo , Ceramidas/metabolismo , Linfocitos/metabolismo , Necrosis/metabolismo , Especies Reactivas de Oxígeno/metabolismo , Animales , Apoptosis , Espectroscopía de Resonancia por Spin del Electrón , Citometría de Flujo , Depuradores de Radicales Libres/farmacología , Glutatión/efectos de los fármacos , Glutatión/metabolismo , Humanos , Células Jurkat , Linfocitos/efectos de los fármacos , Linfocitos/patología , Potencial de la Membrana Mitocondrial/efectos de los fármacos , Ratones , Mitocondrias/efectos de los fármacos , Mitocondrias/metabolismo , Mitocondrias/patologíaRESUMEN
We previously demonstrated that melatonin is involved in the regulation of adrenal glucocorticoid production in diurnal primates through activation of MT1 membrane-bound melatonin receptors. However, whether melatonin has a similar role in nocturnal rodents remains unclear. Using an integrative approach, here we show that the adult rat adrenal gland expresses a functional MT1 melatonin receptor in a rhythmic fashion. We found that: 1) expression of the cognate mRNA encoding for the MT1 membrane-bound melatonin receptor, displaying higher levels in the day/night transition (1800-2200 h); 2) expression of the predicted 37-kDa MT1 polypeptide in immunoblots from adrenals collected at 2200 h but not 1000 h; 3) no expression of the MT2 melatonin receptor mRNA and protein; 4) specific high-affinity 2-[(125)I]iodomelatonin binding in membrane fractions and frozen sections from adrenals collected at 2200 h but not 0800 h (dissociation constant = 14.22 +/- 1.23 pm; maximal binding capacity = 0.88 +/- 0.02 fmol/mg protein); and 5) in vitro clock time-dependent inhibition of ACTH-stimulated corticosterone production by 1-100 nm melatonin, which was reversed by 1 microm luzindole (a melatonin membrane receptor antagonist). Our findings indicate not only expression but also high amplitude diurnal variation of functional MT1 melatonin receptors in the rat adrenal gland. It is conceivable that plasma melatonin may play a role to fine-tune corticosterone production in nocturnal rodents, probably contributing to the down slope of the corticosterone rhythm.
Asunto(s)
Glándulas Suprarrenales/metabolismo , Ritmo Circadiano/fisiología , Receptor de Melatonina MT1/metabolismo , Glándulas Suprarrenales/efectos de los fármacos , Hormona Adrenocorticotrópica/farmacología , Animales , Corticosterona/metabolismo , Masculino , Melatonina/metabolismo , Melatonina/farmacología , ARN Mensajero/metabolismo , Ratas , Ratas Sprague-Dawley , Receptor de Melatonina MT1/genética , Receptor de Melatonina MT2/metabolismoRESUMEN
BACKGROUND: Cardiac output can be measured non invasively by transesophageal Doppler. This is an alternative to measure it by thermodilution with a catheter in the pulmonary artery. AIM: To compare both methods of cardiac output measurement. MATERIAL AND METHODS: Simultaneous measurement of cardiac output by transesophageal Doppler and thermodilution with a catheter in the pulmonary artery in four male critical patients, aged 60+/-12 years, hospitalized in a University Hospital. The Bland and Altman method to compare the concordance between two measurements, was used. RESULTS: Forty measurements were performed. The results of both methods had a correlation coefficient of 0.98. According to the Bland and Altman method, the difference between both methods was -0.5 L with a precision of 0.52 L/min (95% confidence interval -1.51 to 0.52 L/min). Considering that a change between two sequential measurements is considered significant when the difference is more than 15%, both measurements agreed in 83% of cases, that there was a change in cardiac output. CONCLUSIONS: Transesophageal Doppler is a promising non invasive technique to measure cardiac output in critical care patients. It becomes a valid alternative to the thermodilution technique. This preliminary experience must be confirmed in a larger series.
Asunto(s)
Gasto Cardíaco/fisiología , Cateterismo de Swan-Ganz , Ecocardiografía Doppler/métodos , Ecocardiografía Transesofágica/métodos , Termodilución/métodos , Cuidados Críticos , Ecocardiografía Doppler/normas , Ecocardiografía Transesofágica/normas , Humanos , Masculino , Persona de Mediana Edad , Estudios Prospectivos , Termodilución/normasRESUMEN
BACKGROUND: Plasmapheresis is a therapeutic alternative for diseases in which a "humoral factor" has pathogenetic relevance. However it is not devoid of adverse effects. AIM: To review the indications, number of procedures, morbidity and clinical evolution of plasmapheresis in critical patients. PATIENTS AND METHODS: A retrospective and descriptive study in four intensive care units of an University hospital. The severity of patients was evaluated with APACHE II and SOFA scores. RESULTS: Twenty patients were studied. The most common indications of plasmapheresis were thrombotic thrombocytopenic purpura (TTP) in 50% of subjects and small vessel vasculitides in 30%. The number of procedures per patient oscillated between 2 and 14 (mean: 7.1+/-3.3). The registered adverse effects were hypocalcemia in 50% of patients, hypotension in 42.1%, coagulopathy in 35%, hypokalemia in 29%, rash in 20%, procedure related infections in 18% and fever in 10%. There was a significant decrease of 17+/-28% in prothrombin time, after the procedures. Seventy five percent of patients had a favorable evolution. Global mortality rate was 15%. All deaths occurred in patients with TTP and were attributed to the progression of the disease. No death was attributed to the procedure. The initial APACHE II and SOFA scores were 12.4+/-8.4 and 5.3+/-2.9, respectively. Both scores decreased after the procedure. Among other therapeutic measures, 15% of the patients received immunosuppressant treatment, 27% were dialyzed and 32% were mechanically ventilated. CONCLUSIONS: The most common indication of plasmapheresis was TTP. Adverse effects were frequent, however there was no procedure related mortality. The global mortality rate was 15% and all deaths occurred in patients with TTP.