RESUMO
Calcification starts with hydroxyapatite (HA) crystallization on cell membranous components, as with aortic valve interstitial cells (AVICs), wherein a cell-membrane-derived substance containing acidic phospholipids (PPM/PPLs) acts as major crystal nucleator. Since nucleic acid removal is recommended to prevent calcification in valve biosubstitutes derived from decellularized valve scaffolds, the involvement of ribosomal RNA (rRNA) and nuclear chromatin (NC) was here explored in three distinct contexts: (i) bovine AVIC pro-calcific cultures; (ii) porcine aortic valve leaflets that had undergone accelerated calcification after xenogeneic subdermal implantation; and (iii) human aortic valve leaflets affected by calcific stenosis. Ultrastructurally, shared AVIC degenerative patterns included (i) the melting of ribosomes with PPM/PPLs, and the same for apparently well-featured NC; (ii) selective precipitation of silver particles on all three components after adapted von Kossa reactions; and (iii) labelling by anti-rRNA immunogold particles. Shared features were also provided by parallel light microscopy. In conclusion, the present results indicate that rRNA and NC contribute to AVIC mineralization in vitro and in vivo, with their anionic charges enhancing the HA nucleation capacity exerted by PPM/PPL substrates, supporting the concept that nucleic acid removal is needed for valve pre-implantation treatments, besides better elucidating the modality of pro-calcific cell death.
Assuntos
Estenose da Valva Aórtica , Valva Aórtica , Humanos , Animais , Bovinos , Suínos , Valva Aórtica/metabolismo , Durapatita/metabolismo , RNA Ribossômico/metabolismo , Estenose da Valva Aórtica/metabolismo , Modelos Animais , Cromatina/metabolismo , Células CultivadasRESUMO
Calcium-dependent cytosolic phospholipase A2α (cPLA2α) had been previously found to be overexpressed by aortic valve interstitial cells (AVICs) subjected to in vitro calcific induction. Here, cPLA2α expression was immunohistochemically assayed in porcine aortic valve leaflets (iAVLs) that had undergone accelerated calcification subsequent to 2- to 28-day-long implantation in rat subcutis. A time-dependent increase in cPLA2α-positive AVICs paralleled mineralization progression depending on dramatic cell membrane degeneration with the release of hydroxyapatite-nucleating acidic lipid material, as revealed by immunogold particles decorating organelle membranes in 2d-iAVLs, as well as membrane-derived lipid byproducts in 7d- to 28d-iAVLs. Additional positivity was detected for (i) pro-inflammatory IL-6, mostly exhibited by rat peri-implant cells surrounding 14d- and 28d-iAVLs; (ii) calcium-binding osteopontin, with time-dependent increase and no ossification occurrence; (iii) anti-calcific fetuin-A, mostly restricted to blood plasma within vessels irrorating the connective envelopes of 28d-iAVLs; (iv) early apoptosis marker annexin-V, limited to sporadic AVICs in all iAVLs. No positivity was found for either apoptosis executioner cleaved caspase-3 or autophagy marker MAP1. In conclusion, cPLA2α appears to be a factor characterizing AVL calcification concurrently with a distinct still uncoded cell death form also in an animal model, as well as a putative target for the prevention and treatment of calcific valve diseases.
Assuntos
Estenose da Valva Aórtica/metabolismo , Valva Aórtica/metabolismo , Cálcio/metabolismo , Fosfolipases A2 do Grupo IV/metabolismo , Osteogênese/fisiologia , Animais , Apoptose/fisiologia , Autofagia/fisiologia , Calcinose/metabolismo , Células Cultivadas , Modelos Animais de Doenças , Células Intersticiais de Cajal/metabolismo , Masculino , Ratos , Ratos Sprague-Dawley , SuínosRESUMO
Motoneuron activity is modulated by histamine receptors. While H1 and H2 receptors have been widely explored, H3 histamine receptors (H3Rs) have not been sufficiently characterized. This paper targets the effects of the selective activation of H3Rs and their expression on the membranes of large ventral horn cells. The application of selective pharmacological agents to spinal cords isolated from neonatal rats was used to identify the presence of functional H3Rs on the membrane of physiologically identified lumbar motoneurons. Intra and extracellular recordings revealed that H3R agonist, α-methylhistamine, depolarized both single motoneurons and ventral roots, even in the presence of tetrodotoxin, an effect prevented by H3R antagonist, thioperamide. Finally, immunohistochemistry located the expression of H3Rs on a subpopulation of large cells in lamina IX. This study identifies H3Rs as a new exploitable pharmacological target against motor disturbances.
Assuntos
Neurônios Motores/metabolismo , Receptores Histamínicos/metabolismo , Corno Ventral da Medula Espinal/metabolismo , Animais , Metilistaminas/farmacologia , Neurônios Motores/efeitos dos fármacos , Ratos , Corno Ventral da Medula Espinal/efeitos dos fármacosRESUMO
The involvement of calcium-dependent cytosolic phospholipase A2α (cPLA2α) in aortic valve calcification is not exhaustively elucidated. Here, cPLA2α expression in aortic valve interstitial cell (AVIC) pro-calcific cultures simulating either metastatic or dystrophic calcification was estimated by qPCR, Western blotting, and counting of cPLA2α-immunoreactive cells, with parallel ultrastructural examination of AVIC calcific degeneration. These evaluations also involved pro-calcific AVIC cultures treated with cPLA2α inhibitor dexamethasone. cPLA2α over-expression resulted for both types of pro-calcific AVIC cultures. Compared to controls, enzyme content was found to increase by up to 300% and 186% in metastatic and dystrophic calcification-like cultures, respectively. Increases in mRNA amounts were also observed, although they were not as striking as those in enzyme content. Moreover, cPLA2α increases were time-dependent and strictly associated with mineralization progression. Conversely, drastically lower levels of enzyme content resulted for the pro-calcific AVIC cultures supplemented with dexamethasone. In particular, cPLA2α amounts were found to decrease by almost 88% and 48% in metastatic and dystrophic calcification-like cultures, respectively, with mRNA amounts showing a similar trend. Interestingly, these drastic decreases in cPLA2α amounts were paralleled by drastic decreases in mineralization degrees, as revealed ultrastructurally. In conclusion, cPLA2α may be regarded as a crucial co-factor contributing to AVIC mineralization in vitro, thus being an attractive potential target for designing novel therapeutic strategies aimed to counteract onset or progression of calcific aortic valve diseases.
Assuntos
Estenose da Valva Aórtica/patologia , Valva Aórtica/patologia , Calcinose/patologia , Cálcio/metabolismo , Fosfolipases A2 do Grupo IV/metabolismo , Células Intersticiais de Cajal/patologia , Animais , Valva Aórtica/metabolismo , Estenose da Valva Aórtica/metabolismo , Calcinose/metabolismo , Bovinos , Células Cultivadas , Fosfolipases A2 do Grupo IV/genética , Células Intersticiais de Cajal/metabolismoRESUMO
Spinal motoneurons and locomotor networks are regulated by monoamines, among which, the contribution of histamine has yet to be fully addressed. The present study investigates histaminergic regulation of spinal activity, combining intra- and extracellular electrophysiological recordings from neonatal rat spinal cord in vitro preparations. Histamine dose-dependently and reversibly generated motoneuron depolarization and action potential firing. Histamine (20 µM) halved the area of dorsal root reflexes and always depolarized motoneurons. The majority of cells showed a transitory repolarization, while 37% showed a sustained depolarization maintained with intense firing. Extracellularly, histamine depolarized ventral roots (VRs), regardless of blockage of ionotropic glutamate receptors. Initial, transient glutamate-mediated bursting was synchronous among VRs, with some bouts of locomotor activity in a subgroup of preparations. After washout, the amplitude of spontaneous tonic discharges increased. No desensitization or tachyphylaxis appeared after long perfusion or serial applications of histamine. On the other hand, histamine induced single motoneuron and VR depolarization, even in the presence of tetrodotoxin (TTX). During chemically induced fictive locomotion (FL), histamine depolarized VRs. Histamine dose-dependently increased rhythm periodicity and reduced cycle amplitude until near suppression. This study demonstrates that histamine induces direct motoneuron membrane depolarization and modulation of locomotor output, indicating new potential targets for locomotor neurorehabilitation.
Assuntos
Histamina/farmacologia , Neurônios Motores/efeitos dos fármacos , Raízes Nervosas Espinhais/efeitos dos fármacos , Potenciais de Ação/efeitos dos fármacos , Potenciais de Ação/fisiologia , Animais , Estimulação Elétrica , Feminino , Locomoção/efeitos dos fármacos , Locomoção/fisiologia , Masculino , Neurônios Motores/metabolismo , Neurônios Motores/fisiologia , N-Metilaspartato/farmacologia , Ratos , Receptores Ionotrópicos de Glutamato/metabolismo , Raízes Nervosas Espinhais/citologia , Raízes Nervosas Espinhais/metabolismo , Raízes Nervosas Espinhais/fisiologia , Tetrodotoxina/farmacologiaRESUMO
Decellularized porcine aortic valve conduits (AVCs) implanted in a Vietnamese Pig (VP) experimental animal model were matched against decellularized and then cryopreserved AVCs to assess the effect of cryopreservation on graft hemodynamic performance and propensity to in vivo repopulation by host's cells. VPs (n = 12) underwent right ventricular outflow tract substitution using AVC allografts and were studied for 15-month follow-up. VPs were randomized into two groups, receiving AVCs treated with decellularization alone (D; n = 6) or decellularization/cryopreservation (DC; n = 6), respectively. Serial echocardiography was carried out to follow up hemodynamic function. All explanted AVCs were processed for light and electron microscopy. No signs of dilatation, progressive stenosis, regurgitation, and macroscopic calcification were echocardiographically observed in both D and DC groups. Explanted D grafts exhibited near-normal features, whereas the presence of calcification, inflammatory infiltrates, and disarray of elastic lamellae occurred in some DC grafts. In the unaltered regions of AVCs from both groups, almost complete re-endothelialization was observed for both valve cusps and aorta walls. In addition, side-by-side repopulation by recipient's fibroblasts, myofibroblasts, and smooth muscle cells was paralleled by ongoing tissue remodeling, as revealed by the ultrastructural identification of typical canals of collagen fibrillogenesis and elastogenesis-related features. Incipient neo-vascularization and re-innervation of medial and adventitial tunicae of grafted aortic walls were also detected for both D and DC groups. Cryopreservation did not affect post-implantation AVC hemodynamic behavior and was topically propensive to cell repopulation and tissue renewal, although graft deterioration including calcification was present in several areas. Thus, these preliminary data provide essential information on feasibility of decellularization and cryopreservation coupling in the perspective of treatment optimization and subsequent clinical trials using similarly treated human allografts as innovative heart valve substitutes.
Assuntos
Aorta/transplante , Valva Aórtica/transplante , Bioprótese , Implante de Prótese Vascular/instrumentação , Prótese Vascular , Criopreservação , Implante de Prótese de Valva Cardíaca/instrumentação , Próteses Valvulares Cardíacas , Aloenxertos , Animais , Aorta/fisiopatologia , Aorta/ultraestrutura , Valva Aórtica/fisiopatologia , Valva Aórtica/ultraestrutura , Implante de Prótese Vascular/efeitos adversos , Proliferação de Células , Ecocardiografia , Sobrevivência de Enxerto , Implante de Prótese de Valva Cardíaca/efeitos adversos , Hemodinâmica , Microscopia Eletrônica de Transmissão , Modelos Animais , Complicações Pós-Operatórias/patologia , Complicações Pós-Operatórias/fisiopatologia , Suínos , Fatores de TempoRESUMO
Pancreatic Ductal Adenocarcinoma (PDAC) is the most frequent pancreatic cancer and represents one of the most aggressive human neoplasms. Typically identified at advance stage disease, most PDAC tumors are unresectable and resistant to standard therapies. The immunosuppressive microenvironment in PDAC impedes tumor control but a greater understanding of the complex stromal interactions within the tumor microenvironment (TME) and the development of strategies capable of restoring antitumor effector immune responses could be crucial to fight this aggressive tumor and its spread. Natural Killer (NK) cells play a crucial role in cancer immunosurveillance and represent an attractive target for immunotherapies, both as cell therapy and as a pharmaceutical target. This review describes some crucial components of the PDAC TME (collagens, soluble factors and fibroblasts) that can influence the presence, phenotype and function of NK cells in PDAC patients tumor tissue. This focused overview highlights the therapeutic relevance of dissecting the complex stromal composition to define new strategies for NK cell-based immunotherapies to improve the treatment of PDAC.
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Background: Cardiovascular surgeries often require deep hypothermic circulatory arrest and cardiopulmonary bypass (CPB), which can disrupt blood clotting and lead to excessive bleeding. Traditional treatments involve transfusing blood and blood products, which can have adverse effects and place significant strain on the global blood supply. Research suggests that autologous platelet-rich plasmapheresis (aPRP) may reduce the need for transfusions by preserving blood components. However, the impact of aPRP on postoperative blood loss and clinical outcomes in cardiovascular surgery remains controversial. This study aimed to examine the effects of aPRP on postoperative blood loss and recovery in patients undergoing heart valve surgery. Methods: A total of 183 patients were divided into either aPRP or control groups. The aPRP group received aPRP before CPB, whereas the control group did not. The primary endpoint was postoperative bleeding between the groups. The secondary endpoints were postoperative bleeding risk factors and clinical outcome assessment. Logistic regression analysis with covariate adjustment was used to calculate these risk factors. Results: A total of 76 patients (41.5%) in the aPRP group and 107 patients (58.5%) in the control group were included in the analysis. No significant difference was found in the occurrence of postoperative bleeding [odds ratio (OR) =0.53, 95% confidence interval (CI): 0.28-1.00, P=0.05], and the aPRP group had fewer complications than the controls (OR =0.28, 95% CI: 0.10-0.68, P=0.009). However, after adjusting for the New York Heart Association (NYHA) classification, diabetes, arrhythmology, mean activated clotting time (ACTmean), CPB, bleeding, thoracotomy, and body mass index (BMI), there was a significant difference in postoperative bleeding (adjusted OR =0.47, 95% CI: 0.22-0.98, P=0.04) and complications (adjusted OR =0.23, 95% CI: 0.07-0.64, P=0.008) between the two groups. Conclusions: Preoperative aPRP can improve postoperative outcomes and reduce complications in patients undergoing heart valve surgery.
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BACKGROUND: The aim of this study was to match clinical outcomes of heart transplantation (HTx) against histopathologic and ultrastructural characteristics of marginal grafts preserved by cold storage (CS) or ex vivo normothermic perfusion. METHODS: Since 2011, 100 patients had undergone HTx at our institution by using marginal donors (aged ≥55 years, expected ischemic time of >4 hours, left ventricular ejection fraction of ≤50%, interventricular septum thickness of ≥14 mm, drug abuse history, episodes of cardiac arrest, and presence of mild coronary artery disease). CS was utilized in 79 cases (Group 1, 79%), and ex vivo perfusion was utilized in 21 (Group 2, 21%). Pre-operative data, survival, and complications in the first 5 years after HTx were analyzed. Myocardial biopsies were collected at graft harvesting, just before implantation, and immediately after aortic declamping. RESULTS: Pre-operative demographics were similar in the 2 groups. Graft utilization rate with ex vivo perfusion was 81%. Ischemic, cardiopulmonary bypass, and surgical times were shorter in Group 2 patients, who showed a lower incidence of overall complications (33% vs 13%, pâ¯=â¯0.04) and better 5-year survival (log-rank, pâ¯=â¯0.04). Moreover, restoration of hypertrophy-related sarcomere changes and mitigation of reperfusion-dependent myocardium injuries were more frequently observed in Group 2 hearts. CONCLUSIONS: Ex vivo perfusion allows for continuous evaluation of marginal donor hearts, favoring exclusion of unsuitable grafts, reduction of complications, and optimal survival of up to 5 years. Such results, supported by consistent histopathologic and ultrastructural findings, suggest better myocardial preservation.
Assuntos
Criopreservação/instrumentação , Transplante de Coração/métodos , Microscopia Eletrônica de Transmissão/métodos , Miocárdio/ultraestrutura , Preservação de Órgãos/métodos , Perfusão/métodos , Função Ventricular Esquerda/fisiologia , Adolescente , Adulto , Criança , Criopreservação/métodos , Circulação Extracorpórea , Feminino , Seguimentos , Coração , Insuficiência Cardíaca/diagnóstico , Insuficiência Cardíaca/fisiopatologia , Insuficiência Cardíaca/cirurgia , Humanos , Masculino , Pessoa de Meia-Idade , Estudos Retrospectivos , Volume Sistólico/fisiologia , Temperatura , Doadores de Tecidos , Adulto JovemRESUMO
Ectopic calcification of native and bioprosthetic heart valves represents a major public health problem causing severe morbidity and mortality worldwide. Valve procalcific degeneration is known to be caused mainly by calcium salt precipitation onto membranes of suffering non-scavenged cells and dead-cell-derived products acting as major hydroxyapatite nucleators. Although etiopathogenesis of calcification in native valves is still far from being exhaustively elucidated, it is well known that bioprosthesis mineralization may be primed by glutaraldehyde-mediated toxicity for xenografts, cryopreservation-related damage for allografts and graft immune rejection for both. Instead, mechanical valves, which are free from calcification, are extremely thrombogenic, requiring chronic anticoagulation therapies for transplanted patients. Since surgical substitution of failed valves is still the leading therapeutic option, progressive improvements in tissue engineering techniques are crucial to attain readily available valve implants with good biocompatibility, proper functionality and long-term durability in order to meet the considerable clinical demand for valve substitutes. Bioengineered valves obtained from acellular non-valvular scaffolds or decellularized native valves are proving to be a compelling alternative to mechanical and bioprosthetic valve implants, as they appear to permit repopulation by the host's own cells with associated tissue remodelling, growth and repair, besides showing less propensity to calcification and adequate hemodynamic performances. In this review, insights into valve calcification onset as revealed by in vivo and in vitro procalcific models are updated as well as advances in the field of valve bioengineering.
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Galectin-1 is a 14 kDa beta-galactoside binding protein, capable of forming lattice-like structures with glycans of cellular glycoconjugates and inducing intracellular signaling. The expression of Galectin-1 in porcine cartilage is described in this work for the first time. Immunocytochemical methods revealed distinct distribution patterns for both articular and growth plate cartilage. In articular cartilage, the highest reactivity for Galectin-1 was found in all chondrocytes at the superficial zone and in most of those at the lower layer of the middle zone. In the growth plate, marked reactivity was seen in chondrocytes at the proliferative zone and reached a maximum level for the column-forming cells at the hypertrophic zone. In addition, different Galectin-1 distribution patterns were observed at the subcellular level. With regards to the metabolic effects of Galectin-1, the results in vitro seem to indicate an inhibitory effect of Galectin-1 on articular chondrocyte anabolism (i.e. inhibition of cell proliferation and anabolic gene expression) and a stimulation of catabolic processes (i.e. induction of matrix degradation and hypertrophy marker expression). These data represent a starting point for the understanding the molecular mechanisms underlining ECM-Galectin-1 interaction and the subsequent signaling-cell transduction processes involving cartilage formation and maturation.
Assuntos
Cartilagem , Condrócitos/fisiologia , Matriz Extracelular , Galectina 1/metabolismo , Animais , Cartilagem/citologia , Cartilagem/metabolismo , Adesão Celular/fisiologia , Ciclo Celular/fisiologia , Proliferação de Células , Condrócitos/citologia , Matriz Extracelular/química , Matriz Extracelular/metabolismo , Galectina 1/genética , SuínosRESUMO
PURPOSE: To report the results of ultrastructural analysis of the postoperative effects of ab interno trabeculectomy in a human eye. SETTING: Department of Ophthalmology, Palmanova Hospital, Palmanova, Udine, Italy. METHODS: A 60-year-old woman with cataract and glaucoma had enucleation for a choroidal melanoma 10 days after ab interno trabeculectomy combined with phacoemulsification. A second ab interno trabeculectomy was performed after enucleation to evaluate the outcomes of the previous trabeculectomy. Light and transmission electron microscopy analyses were performed on samples excised from areas (1) not subjected to a procedure (control samples), (2) that had ab interno trabeculectomy before enucleation, and (3) that had ab interno trabeculectomy immediately after enucleation. RESULTS: Control samples showed normal trabecular features. Semithin sections of all ab interno trabeculectomy samples showed full-thickness removal of trabeculum segments, with Schlemm's canal lumen opening into the anterior chamber and apparent preservation of the adjacent structures. On ultrathin sections of samples that had ab interno trabeculectomy before enucleation, the endothelium lining the outer wall of Schlemm's canal and other angle components showed intact ultrastructural features. In trabecular beams that were not removed, the extracellular matrix appeared to have maintained its fine texture and was free of activated fibroblasts or leucocyte infiltrates. CONCLUSIONS: Observations confirm that ab interno trabeculectomy causes direct communication between Schlemm's canal lumen and the anterior chamber in vivo and immediately after enucleation during the early postoperative period. The absence of an evident inflammatory reaction in the examined case should be considered with caution because of possible tumor-induced immune suppression.
Assuntos
Glaucoma/patologia , Malha Trabecular/cirurgia , Malha Trabecular/ultraestrutura , Trabeculectomia/métodos , Câmara Anterior/ultraestrutura , Catarata/complicações , Neoplasias da Coroide/patologia , Enucleação Ocular , Feminino , Glaucoma/cirurgia , Humanos , Pressão Intraocular , Melanoma/patologia , Pessoa de Meia-Idade , Facoemulsificação , Resultado do TratamentoRESUMO
Valve dystrophic calcification is a common disorder affecting normophosphatemic subjects. Here, cultured aortic valve interstitial cells (AVICs) were treated 3 to 28 days with phosphate (Pi) concentrations spanning the normal range in humans (0.8, 1.3, and 2.0 mM) alone or supplemented with proinflammatory stimuli to assess possible priming of dystrophic-like calcification. Compared with controls, spectrophotometric analyses revealed marked increases in calcium amounts and alkaline phosphatase activity for 2.0-mM-Pi-containing cultures, with enhancing by proinflammatory mediators. Ultrastructurally, AVICs treated with low/middle Pi concentrations showed an enormous endoplasmic reticulum (ER) enclosing organelle debris, so apparently executing a survival-related atypical macroautophagocytosis, consistently with ultracytochemical demonstration of ER-associated acid phosphatase activity and decreases in autophagosomes and immunodetectable MAP1LC3. In contrast, AVICs cultured at 2.0-mM Pi underwent mineralization due to intracellular release and peripheral layering of phospholipid-rich material acting as hydroxyapatite nucleator, as revealed by Cuprolinic Blue and von Kossa ultracytochemical reactions. Lack of immunoblotted caspase-3 cleaved form indicated apoptosis absence for all cultures. In conclusion, fates of cultured AVICs were crucially driven by Pi concentration, suggesting that serum Pi levels just below the upper limit of normophosphatemia in humans may represent a critical watershed between macroautophagy-associated cell restoring and procalcific cell death.
Assuntos
Valva Aórtica/citologia , Valva Aórtica/patologia , Calcinose/patologia , Fosfatos/metabolismo , Fosfatase Alcalina/metabolismo , Animais , Valva Aórtica/metabolismo , Valva Aórtica/ultraestrutura , Autofagia , Calcinose/metabolismo , Cálcio/metabolismo , Bovinos , Sobrevivência Celular , Células Cultivadas , Retículo Endoplasmático/metabolismo , Retículo Endoplasmático/patologia , Retículo Endoplasmático/ultraestruturaRESUMO
Several animal models are currently used for the surgical implantation of either biologic or biopolymeric scaffolds in order to provide in vivo assessment of tissue-engineered heart valves. The Vietnamese pig (VP) is herein proposed as a suitable recipient to test the function of novel bioengineered valve substitutes, in the reconstruction of the right ventricular outflow tract (RVOT). This review aims to provide a complete and exhaustive panel of physiological parameters and methodological information for preclinical studies of tissue-engineered heart valves in the VP animal model.
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Próteses Valvulares Cardíacas , Engenharia Tecidual , Aloenxertos , Animais , Valva Aórtica/cirurgia , Ecocardiografia , Regeneração Tecidual Guiada , Modelos Animais , Desenho de Prótese , SuínosAssuntos
Seleção do Doador , Parada Cardíaca/etiologia , Insuficiência Cardíaca/cirurgia , Transplante de Coração , Miocárdio/ultraestrutura , Sarcômeros/ultraestrutura , Doadores de Tecidos , Coleta de Tecidos e Órgãos/efeitos adversos , Adulto , Idoso , Parada Cardíaca/patologia , Parada Cardíaca/fisiopatologia , Insuficiência Cardíaca/diagnóstico , Insuficiência Cardíaca/fisiopatologia , Humanos , Masculino , Resultado do TratamentoRESUMO
Diurnal variations in tonic pain reactions have been described in mice tested in Spring, but the underlying mechanisms are still unknown. We tested the potential role of melatonin, a key hormone in the control of neuro-endocrine circadian rhythms. The experiments were performed in male CBA/J mice housed under controlled temperature, humidity, and light (12/12 dark/light cycle) conditions, during the Light (7-10a.m.) or Dark (7-10p.m.) phases of the diurnal cycle. In a first group of experiments, animals were either pretreated with i.p. saline (controls) or with the melatonin receptor antagonist, luzindole (30 mg/kg), before the s.c. injection of a dilute formalin solution into a hindpaw. In control animals, pain-related behavioral reactions (licking and flinching) were higher in the evening (Dark) than in the morning (Light), both during the first (0-10 min) and the second (11-55 min) phase of the response to s.c. formalin. In animals pre-treated with luzindole, no diurnal changes occurred, pain reactions in the Dark being similar to those of the Light Control group. In a second group of experiments, artificial pinealectomy, obtained by exposing animals to continuous light for 48 h, also reduced pain reactions in the evening to levels comparable to those in the morning. Receptor autoradiography showed lower binding availability at spinal cord level in mice sacrificed during the Dark, as expected from the circadian pattern of melatonin secretion. A further significant decrease of melatonin receptor binding was induced by noxious stimulation. These results suggest a proalgesic role of endogenous melatonin in tonic pain.
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Ritmo Circadiano/fisiologia , Melatonina/fisiologia , Dor/fisiopatologia , Animais , Autorradiografia/métodos , Comportamento Animal , Sítios de Ligação , Formaldeído , Asseio Animal/efeitos dos fármacos , Técnicas In Vitro , Isótopos de Iodo , Masculino , Camundongos , Camundongos Endogâmicos CBA , Atividade Motora/efeitos dos fármacos , Dor/induzido quimicamente , Medição da Dor/métodos , Glândula Pineal/lesões , Glândula Pineal/fisiologia , Receptores de Melatonina/antagonistas & inibidores , Receptores de Melatonina/metabolismo , Medula Espinal/efeitos dos fármacos , Medula Espinal/metabolismo , Triptaminas/farmacologiaRESUMO
We identified 220-kD protein in bovine skeletal muscle homogenate by affinity chromatography on an agarose column and subsequent SDS-PAGE. Peptide mass fingerprinting (MALDI mass spectrometry) and internal sequence analysis revealed that this protein has homology with several members of the myosin superfamily, particularly with human cardiac beta-myosin heavy chain (beta-MHC). A rabbit polyclonal antibody against the 220-kD protein specifically stained a 220-kD band in Western blots of skeletal muscle homogenate. Immunohistochemical experiments on cryostat sections demonstrated that in skeletal muscle this protein is exclusively localized at the neuromuscular junctions, no immunoreactivity being present at the myofibril level. Because of its relative homology with cardiac beta-MHC, we also investigated the distribution of the 220-kD protein in bovine heart. In cardiac fibers, 220-kD protein-related immunoreactivity was restricted to the intercalated disks, whereas myofibrils were completely devoid of specific immunoreactivity. This distribution pattern was completely different from that of cardiac beta-MHC, which involved myofibrils. Because of the above biochemical and immunohistochemical features, the 220-kD protein we have identified is suggested to be a novel member of the non-muscle (non-sarcomeric) myosin family.
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Músculo Esquelético/metabolismo , Miosina Tipo II/metabolismo , Junção Neuromuscular/metabolismo , Animais , Miosinas Cardíacas/química , Miosinas Cardíacas/metabolismo , Bovinos , Imuno-Histoquímica , Peso Molecular , Músculo Esquelético/citologia , Miocárdio/metabolismo , Miosina Tipo II/química , Mapeamento de Peptídeos , Coelhos , Análise de Sequência de Proteína , Homologia de Sequência de AminoácidosRESUMO
BACKGROUND: Heart valve bioprostheses for cardiac valve replacement are fabricated by xeno- or allograft tissues. Decellularization techniques and tissue engineering technologies applied to these tissues might contribute to the reduction in risk of calcification and immune response. Surprisingly, there are few data on the cell phenotypes obtained after cellularizing these naturally-derived biomaterials in comparison to those expressed in the intact valve. METHODS: Aortic valve interstitial cells (VIC) were used to repopulate the corresponding valve leaflets after a novel decellularization procedure based on the use of ionic and nonionic detergents. VIC from leaflet microexplants at the third passage were utilized to repopulate the decellularized leaflets. Intact, decellularized and repopulated valve leaflets and cultured VIC were examined by immunocytochemical procedures with a panel of antibodies to smooth muscle and nonmuscle differentiation antigens. Intact and cellularized leaflets were also investigated with Western blotting and transmission electron microscopy, respectively. RESULTS: Myofibroblasts and smooth muscle cells (SMC) were mostly localized to the ventricularis of the leaflet whereas fibroblasts were dispersed unevenly. Cultured VIC were comprised of myofibroblasts and fibroblasts with no evidence of endothelial cells and SMC. Two weeks after VIC seeding into decellularized leaflets, grafted cells were found penetrating the bioscaffold. The immunophenotypic and ultrastructural properties of the grafted cells indicated that a VIC heterogeneous mesenchymal cell population was present: fibroblasts, myofibroblasts, SMC, and endothelial cells. CONCLUSIONS: VIC seeding on detergent-treated valve bioscaffolds has the cellular potential to reconstruct a viable aortic valve.
Assuntos
Valva Aórtica/citologia , Bioprótese , Técnicas Citológicas , Animais , Western Blotting , Fibroblastos/citologia , Imuno-Histoquímica , Microscopia Eletrônica , Músculo Liso/citologia , Suínos , Engenharia Tecidual , Transplante Heterólogo , Transplante HomólogoRESUMO
Tissue-engineered heart valves are proposed as novel viable replacements granting longer durability and growth potential. However, they require extensive in vitro cell-conditioning in bioreactor before implantation. Here, the propensity of non-preconditioned decellularized heart valves to spontaneous in body self-regeneration was investigated in a large animal model. Decellularized porcine aortic valves were evaluated for right ventricular outflow tract (RVOT) reconstruction in Vietnamese Pigs (nâ=â11) with 6 (nâ=â5) and 15 (nâ=â6) follow-up months. Repositioned native valves (nâ=â2 for each time) were considered as control. Tissue and cell components from explanted valves were investigated by histology, immunohistochemistry, electron microscopy, and gene expression. Most substitutes constantly demonstrated in vivo adequate hemodynamic performances and ex vivo progressive repopulation during the 15 implantation months without signs of calcifications, fibrosis and/or thrombosis, as revealed by histological, immunohistochemical, ultrastructural, metabolic and transcriptomic profiles. Colonizing cells displayed native-like phenotypes and actively synthesized novel extracellular matrix elements, as collagen and elastin fibers. New mature blood vessels, i.e. capillaries and vasa vasorum, were identified in repopulated valves especially in the medial and adventitial tunicae of regenerated arterial walls. Such findings correlated to the up-regulated vascular gene transcription. Neoinnervation hallmarks were appreciated at histological and ultrastructural levels. Macrophage populations with reparative M2 phenotype were highly represented in repopulated valves. Indeed, no aspects of adverse/immune reaction were revealed in immunohistochemical and transcriptomic patterns. Among differentiated elements, several cells were identified expressing typical stem cell markers of embryonic, hematopoietic, neural and mesenchymal lineages in significantly higher number and specific topographic distribution in respect to control valves. Following the longest follow-up ever realized in preclinical models, non-preconditioned decellularized allogeneic valves offer suitable microenvironment for in vivo cell homing and tissue remodeling. Manufactured with simple, timesaving and cost-effective procedures, these promising valve replacements hold promise to become an effective alternative, especially for pediatric patients.
Assuntos
Implante de Prótese de Valva Cardíaca , Próteses Valvulares Cardíacas , Regeneração/fisiologia , Aloenxertos/ultraestrutura , Animais , Forma Celular , Sobrevivência Celular , Células Cultivadas , Perfilação da Expressão Gênica , Imuno-Histoquímica , Imunofenotipagem , Sus scrofa , Transplante HomólogoRESUMO
Metastatic calcification of cardiac valves is a common complication in patients affected by chronic renal failure. In this study, primary bovine aortic valve interstitial cells (AVICs) were subjected to pro-calcific treatments consisting in cell stimulation with (i) elevated inorganic phosphate (Pi = 3 mM), to simulate hyperphosphatemic conditions; (ii) bacterial endotoxin lipopolysaccharide (LPS), simulating direct effects by microbial agents; and (iii) conditioned media (CM) derived from cultures of either LPS-stimulated heterogenic macrophages (commercial murine RAW264.7 cells) or LPS-stimulated fresh allogenic monocytes/macrophages (bCM), simulating consequent inflammatory responses, alone or combined. Compared to control cultures, spectrophotometric assays revealed shared treatment-dependent higher values of both calcium amounts and alkaline phosphatase activity for cultures involving the presence of elevated Pi. Ultrastructurally, shared peculiar pro-calcific degeneration patterns were exhibited by AVICs from these latter cultures irrespectively of the additional treatments. Disappearance of all cytomembranes and concurrent formation of material showing positivity to Cuprolinic Blue and co-localizing with silver precipitation were followed by the outcropping of such a material, which transformed in layers outlining the dead cells. Subsequent budding of these layers resulted in the formation of bubbling bodies and concentrically laminated calcospherulae mirroring those in actual soft tissue calcification. In conclusion, the in vitro models employed appear to be reliable tools for simulating metastatic calcification and indicate that hyperphosphatemic-like conditions could trigger valve calcification per se, with LPS and allogenic macrophage-derived secretory products acting as possible calcific enhancers via inflammatory responses.