RESUMEN

BACKGROUND: This case report describes a rare benign tumour, which presented as discrete areas of gingival hyperplasia affecting both the mandible and the maxilla. METHOD: Surgical excision of the lesions was carried out under local anaesthetic. Histopathological examination confirmed the diagnosis of oral myofibromatosis. RESULTS: The condition responded to surgical excision and appears to have limited growth potential. It affects a wide spectrum of ages and can be alarming due to rapid enlargement and ulceration, so careful diagnosis is important to avoid unnecessary aggressive treatment.

Asunto(s)

Hiperplasia Gingival/etiología , Neoplasias Gingivales/complicaciones , Miofibromatosis/complicaciones , Actinas/análisis , Adolescente , Diagnóstico Diferencial , Fibroblastos/patología , Neoplasias Gingivales/patología , Humanos , Masculino , Músculo Liso/patología , Miofibromatosis/patología

RESUMEN

Dental pathology and/or treatment have been linked to a small number of brain abscesses as possible sources of infection. A further case is presented, in which a dental site is implicated. A review of the evidence was undertaken. A wide range of dental procedures had been implicated. In some cases the brain isolate was not of dental origin. In many, the diagnosis was one of exclusion. In order to confirm the role of odontogenic infection in the pathogenesis of brain abscess, modern sampling techniques should be used to precisely identify the isolates. The causal organism should be identified in both oral and cranial sites.

Asunto(s)

Absceso Encefálico/etiología , Infección Focal Dental/complicaciones , Absceso Periodontal/complicaciones , Absceso Encefálico/diagnóstico por imagen , Absceso Encefálico/microbiología , Infección Focal Dental/microbiología , Hemiplejía/etiología , Humanos , Masculino , Persona de Mediana Edad , Absceso Periodontal/microbiología , Streptococcus sanguis/aislamiento & purificación , Tomografía Computarizada por Rayos X

RESUMEN

Endothelial cells release nitric oxide (NO) acutely in response to increased "flow" or fluid shear stress (FSS), and the increase in NO production is correlated with enhanced phosphorylation and activation of endothelial nitric oxide synthase (eNOS). Both vascular endothelial growth factor and FSS activate endothelial protein kinase B (PKB) by way of incompletely understood pathway(s), and, in turn, PKB phosphorylates eNOS at Ser-1179, causing its activation. In this study, we found that either FSS or insulin stimulated insulin receptor substrate-1 (IRS-1) tyrosine and serine phosphorylation and increased IRS-1-associated phosphatidylinositol 3-kinase activity, phosphorylation of PKB Ser-473, phosphorylation of eNOS Ser-1179, and NO production. Brief pretreatment of bovine aortic endothelial cells with tumor necrosis factor-alpha (TNF-alpha) inhibited the above described FSS- or insulin-stimulated protein phosphorylation events and almost totally inhibited FSS- or insulin-stimulated NO production. These data indicate that FSS and insulin regulate eNOS phosphorylation and NO production by overlapping mechanisms. This study suggests one potential mechanism for the development of endothelial dysfunction in disease states with alterations in insulin regulation and increased TNF-alpha levels.

Asunto(s)

Factores de Crecimiento Endotelial/farmacología , Endotelio Vascular/fisiología , Insulina/farmacología , Linfocinas/farmacología , Óxido Nítrico Sintasa/metabolismo , Óxido Nítrico/metabolismo , Proteínas Serina-Treonina Quinasas , Proteínas Proto-Oncogénicas/metabolismo , Transducción de Señal/fisiología , Factor de Necrosis Tumoral alfa/farmacología , Animales , Aorta , Bovinos , Células Cultivadas , Endotelio Vascular/citología , Endotelio Vascular/efectos de los fármacos , Activación Enzimática , Proteínas Sustrato del Receptor de Insulina , Cinética , Óxido Nítrico Sintasa/efectos de los fármacos , Óxido Nítrico Sintasa de Tipo III , Fosfoproteínas/metabolismo , Fosforilación , Fosfoserina/metabolismo , Fosfotreonina/metabolismo , Fosfotirosina/metabolismo , Proteínas Proto-Oncogénicas c-akt , Transducción de Señal/efectos de los fármacos , Estrés Mecánico , Factor A de Crecimiento Endotelial Vascular , Factores de Crecimiento Endotelial Vascular

RESUMEN

Integrin-mediated substrate adhesion of endothelial cells leads to intracellular signaling, including the activation of ERK 1/2 (extracellular regulated kinases 1 and 2), members of the mitogen-activated protein kinase (MAPK) family. MKP-1 is a dual-specificity protein phosphatase that may play an important role in regulating MAPK activity through dephosphorylation of threonine and tyrosine. Adhesion of human umbilical vein endothelial cells to fibronectin increased MKP-1 protein and mRNA levels, which reached a maximum at 60 min, while MAPK activity was maximal at 30 min. The MEK inhibitor PD98059 blocked activation of MAPK as well as the induction of MKP-1 during adhesion. The transcription inhibitor actinomycin D blocked MKP-1 induction and produced prolonged MAPK activation during adhesion. In contrast, endothelial adhesion to poly-L-lysine did not alter MAPK activity or MKP-1 levels. These findings demonstrate that integrin-mediated adhesion of endothelial cells to fibronectin results in transcriptional activation of MKP-1 through a MAPK-dependent mechanism. Regulation of MKP-1 by MAPK likely represents an important negative-feedback mechanism.

Asunto(s)

Adhesión Celular/fisiología , Proteínas de Ciclo Celular , Endotelio Vascular/citología , Endotelio Vascular/metabolismo , Fibronectinas/metabolismo , Proteínas Inmediatas-Precoces/metabolismo , Fosfoproteínas Fosfatasas , Proteínas Tirosina Fosfatasas/metabolismo , Células Cultivadas , Dactinomicina/farmacología , Fosfatasa 1 de Especificidad Dual , Endotelio Vascular/efectos de los fármacos , Activación Enzimática/efectos de los fármacos , Flavonoides/farmacología , Humanos , Proteínas Inmediatas-Precoces/genética , Integrinas/metabolismo , Quinasas de Proteína Quinasa Activadas por Mitógenos/antagonistas & inhibidores , Proteínas Quinasas Activadas por Mitógenos/metabolismo , Proteína Fosfatasa 1 , Proteínas Tirosina Fosfatasas/genética , ARN Mensajero/genética , ARN Mensajero/metabolismo , Transcripción Genética/efectos de los fármacos

RESUMEN

Endothelial cells release nitric oxide (NO) acutely in response to increased laminar fluid shear stress, and the increase is correlated with enhanced phosphorylation of endothelial nitric-oxide synthase (eNOS). Phosphoamino acid analysis of eNOS from bovine aortic endothelial cells labeled with [(32)P]orthophosphate demonstrated that only phosphoserine was present in eNOS under both static and flow conditions. Fluid shear stress induced phosphate incorporation into two specific eNOS tryptic peptides as early as 30 s after initiation of flow. The flow-induced tryptic phosphopeptides were enriched, separated by capillary electrophoresis with intermittent voltage drops, also known as "peak parking," and analyzed by collision-induced dissociation in a tandem mass spectrometer. Two phosphopeptide sequences determined by tandem mass spectrometry, TQpSFSLQER and KLQTRPpSPGPPPAEQLLSQAR, were confirmed as the two flow-dependent phosphopeptides by co-migration with synthetic phosphopeptides. Because the sequence (RIR)TQpSFSLQER contains a consensus substrate site for protein kinase B (PKB or Akt), we demonstrated that LY294002, an inhibitor of the upstream activator of PKB, phosphatidylinositol 3-kinase, inhibited flow-induced eNOS phosphorylation by 97% and NO production by 68%. Finally, PKB phosphorylated eNOS in vitro at the same site phosphorylated in the cell and increased eNOS enzymatic activity by 15-20-fold.

Asunto(s)

Cromonas/farmacología , Inhibidores Enzimáticos/farmacología , Exodesoxirribonucleasas/metabolismo , Morfolinas/farmacología , Óxido Nítrico Sintasa/metabolismo , Óxido Nítrico/biosíntesis , Inhibidores de las Quinasa Fosfoinosítidos-3 , Secuencia de Aminoácidos , Animales , Secuencia de Bases , Bovinos , Células Cultivadas , Cartilla de ADN , Exodesoxirribonucleasas/genética , Exodesoxirribonucleasas/aislamiento & purificación , Cinética , Espectrometría de Masas , Datos de Secuencia Molecular , Óxido Nítrico Sintasa/química , Óxido Nítrico Sintasa de Tipo III , Mapeo Peptídico , Fosfopéptidos/química , Fosforilación

RESUMEN

Electrospray ionization (ESI) tandem mass spectrometry (MS/MS) of peptides in conjunction with automated sequence database searching of the resulting collision-induced dissociation (CID) spectra has become a powerful method for the identification of purified proteins or the components of protein mixtures. The success of the method is critically dependent on the manner by which the peptides are introduced into the mass spectrometer. In this report, we describe a capillary electrophoresis-based system for the automated, sensitive analysis of complex peptide mixtures. The system consists of an ESI-MS/MS instrument, a solid-phase extraction (SPE)-capillary zone electrophoresis (CZE) device for peptide concentration and separation, and an algorithm written in Instrument Control Language (ICL) which modulates the electrophoretic conditions in a data-dependent manner to optimize available time for the generation of high-quality CID spectra of peptides in complex samples. We demonstrate that the data-dependent modulation of the electric field significantly expands the analytical window for each peptide analyzed and that the sensitivity of the SPE-CZE technique is not noticeably altered by the procedure. By applying the technique to the analysis of in vivo phosphorylation sites of endothelial nitric oxide synthase (eNOS), we demonstrate the power of this system for the MS/MS analysis of minor peptide species in complex samples such as phosphopeptides generated by the proteolytic digestion of a large protein, eNOS, phosphorylated at low stoichiometry.

Asunto(s)

Óxido Nítrico Sintasa/análisis , Péptidos/análisis , Fosfopéptidos/análisis , Secuencia de Aminoácidos , Animales , Bovinos , Electroforesis Capilar , Espectrometría de Masas , Datos de Secuencia Molecular , Óxido Nítrico Sintasa de Tipo III

RESUMEN

An understanding of a broader concept of health is increasingly important for all health professionals, including dentists, and has recently been incorporated as a key principle in the Government White Paper, The New NHS. This aims to deliver a dependable, high quality, egalitarian health service. In the past, performance measurements in the UK have often relied simply on those areas which are most easily quantified. For example, within the hospital service, performance was measured in terms of the cost and the number of finished consultant episodes, from which the 'purchaser efficiency index' was calculated. This tended to produce a driving force rewarding those doing more rather than those doing more better. It is analogous to the system which has been the backbone of NHS dental practice for many years, 'fee per item of service', where throughout is rewarded rather than outcome. However, the White Paper has signalled a move away from simply counting activity. From April 1999 within the hospital service the purchaser efficiency index has been replaced with more rounded measures, reflecting the changing concepts of health, in a new broader performance framework to determine what really counts for patients. It will focus on measuring health improvement, fairer access, better quality and outcome, including the views of patients.

Asunto(s)

Atención Odontológica , Salud Bucal , Indicadores de Salud , Humanos , Calidad de Vida , Odontología Estatal , Medicina Estatal , Reino Unido

RESUMEN

Axl is a receptor tyrosine kinase originally identified as a transforming gene product in human myeloid leukemia cells. Cultured rat vascular smooth muscle cells also express Axl, where it has been proposed that Axl may play a role in cell proliferation. In the current study, we tested the hypotheses that Axl expression would parallel neointima formation in balloon-injured rat carotid, and that Axl expression would be regulated by growth factors present at sites of vascular injury. Ribonuclease protection assay showed dynamic increases in Axl mRNA in vessels, with peak expression 7 and 14 days after injury. Immunohistochemical analysis confirmed these results and demonstrated that Axl protein expression was localized primarily to cells of the neointima after injury. Northern blot analysis indicated increased mRNA expression for the secreted Axl ligand, Gas6, in injured carotids, with a time course paralleling that of Axl upregulation. Axl and Gas6 expression were temporally correlated with neointima formation, suggesting a role for Axl signaling in this process. Other studies, performed in cultured rat vascular smooth muscle cells, revealed positive regulation of Axl mRNA expression by thrombin or angiotensin II but not by basic fibroblast growth factor, platelet-derived growth factor-BB, or transforming growth factor-ss1. Western blot analysis confirmed these results, showing that Axl protein expression was specifically increased by thrombin or angiotensin II. Our results implicate Axl as a potential mediator of vascular smooth muscle migration and proliferation caused by vascular injury and G protein-coupled receptor agonists.

Asunto(s)

Traumatismos de las Arterias Carótidas , Cateterismo/efectos adversos , Proteínas de Unión al GTP/metabolismo , Proteínas Oncogénicas/biosíntesis , Proteínas Tirosina Quinasas Receptoras/biosíntesis , Receptores de Superficie Celular/agonistas , Angiotensina II/farmacología , Animales , Factor 2 de Crecimiento de Fibroblastos/farmacología , Masculino , Factor de Crecimiento Derivado de Plaquetas/farmacología , Proteínas Proto-Oncogénicas , Ratas , Ratas Sprague-Dawley , Receptores de Superficie Celular/metabolismo , Trombina/farmacología , Factor de Crecimiento Transformador beta/farmacología , Tirosina Quinasa del Receptor Axl

RESUMEN

PURPOSE: We investigated whether control of constitutive endothelial cell nitric oxide synthase (cNOS) and nitric oxide (NO) by changes in shear stress might be important for the regulation of smooth muscle cell (SMC) growth and vascular diameter. METHODS: Bilateral femoral arteriovenous fistulas were placed in baboons to increase the blood flow in the external iliac arteries. At 2 months, the fistula was ligated on one side to restore normal flow (flow switch). RESULTS: In response to flow switch and a decrease in shear stress, iliac artery lumenal area decreased and SMC proliferation was induced. A decline in NO production, cNOS messenger RNA (mRNA), and protein were associated with these biological effects. In a subset of animals with iliac arteries under high flow, infusion of N(omega)-nitro-L-arginine, an inhibitor of cNOS, did not induce proliferation. CONCLUSION: Shear stress can regulate cNOS, vasoconstriction, and SMC proliferation. A decrease in nitric oxide may be necessary, but is not sufficient to induce SMC proliferation in response to a decrease in blood flow.

Asunto(s)

Músculo Liso Vascular/fisiología , Óxido Nítrico Sintasa/fisiología , Animales , Arteria Ilíaca/citología , Masculino , Músculo Liso Vascular/citología , Óxido Nítrico/fisiología , Óxido Nítrico Sintasa/genética , Óxido Nítrico Sintasa de Tipo III , Nitroarginina/farmacología , Papio , ARN Mensajero/análisis , Estrés Mecánico

RESUMEN

Endothelial nitric oxide synthase (eNOS) has been shown to be regulated both transcriptionally and posttranslationally in cultured endothelial cells, but eNOS regulatory mechanisms in vivo have not been elucidated. Because one of the strongest stimuli for eNOS expression in tissue culture is cell proliferation and because increased NO production would be beneficial in the setting of arterial injury, we hypothesized that eNOS expression should be increased in regenerating endothelium after a denuding injury. Rat aortas underwent partial endothelial denudation by passage of a deflated balloon catheter, and eNOS expression was studied 48 hours after injury. Immunohistochemistry with eNOS monoclonal antibody, NADPH diaphorase activity assay under conditions specific for eNOS, and mRNA hybridization were performed in situ on perfusion-fixed rat aortic segments. The vessels were studied en face to enhance visualization compared with cross sections. eNOS protein and mRNA expression were significantly increased in regenerating and migrating endothelial cells at the wound edge, with translocation of eNOS to the plasma membrane at the leading edge. Similar results were obtained when endothelial cells were studied in a tissue culture wound model. An important role for transforming growth factor (TGF)-beta1 in regulating eNOS expression was suggested by the ability of a TGF-beta1-neutralizing antibody to limit induction of eNOS at the wound edge. Increased eNOS expression after wounding appears to be related to signal events associated with cell migration as well as proliferation, because eNOS expression in vivo increased in nonproliferating cells and TGF-beta1-neutralizing antibody inhibited eNOS expression but stimulated proliferation. The current study is the first to suggest an important role in vivo for increased eNOS, and perhaps NO production, in the process of endothelial regeneration and wound repair.

Asunto(s)

Aorta/enzimología , Endotelio Vascular/enzimología , Óxido Nítrico Sintasa/metabolismo , Regeneración/fisiología , Análisis de Varianza , Animales , Aorta/fisiología , Técnicas de Cultivo , Endotelio Vascular/fisiología , Procesamiento de Imagen Asistido por Computador , Inmunohistoquímica , Hibridación in Situ , Masculino , NADPH Deshidrogenasa/metabolismo , Óxido Nítrico Sintasa de Tipo III , Ratas , Estadísticas no Paramétricas

RESUMEN

In this review, the role of tyrosine kinases in angiotensin II-mediated signal transduction pathways in vascular smooth muscle is discussed. Angiotensin II was isolated by virtue of its vasoconstrictor abilities and has long been thought to play a critical role in hypertension. However, recent studies indicate important roles for angiotensin II in inflammation, atherosclerosis, and congestive heart failure. The expanding role of angiotensin II indicates that multiple signal transduction pathways are likely to be activated in a tissue-specific manner. Exciting recent data show that angiotensin II directly stimulates tyrosine kinases, including pp60(c-src) kinase (c-Src), focal adhesion kinase (FAK), and Janus kinases (JAK2 and TYK2). Angiotensin II may activate receptor tyrosine kinases, such as Axl and platelet-derived growth factor, by as-yet-undefined autocrine mechanisms. Finally, unknown tyrosine kinases may mediate tyrosine phosphorylation of Shc, Raf, and phospholipase C-gamma after angiotensin II stimulation. These angiotensin II-regulated tyrosine kinases appear to be required for angiotensin II effects, such as vasoconstriction, proto-oncogene expression, and protein synthesis, on the basis of studies with tyrosine kinase inhibitors. Thus, understanding angiotensin II-stimulated signaling events, especially those related to tyrosine kinase activity, may form the basis for the development of new therapies for cardiovascular diseases.

Asunto(s)

Angiotensina II/fisiología , Músculo Liso Vascular/citología , Proteínas Tirosina Quinasas/fisiología , Transducción de Señal/fisiología , Moléculas de Adhesión Celular/fisiología , Células Cultivadas , Quinasa 1 de Adhesión Focal , Proteína-Tirosina Quinasas de Adhesión Focal , Humanos , Desarrollo de Músculos , Músculo Liso Vascular/crecimiento & desarrollo , Fosforilación , Factor de Crecimiento Derivado de Plaquetas/fisiología , Proto-Oncogenes Mas , Familia-src Quinasas/fisiología

RESUMEN

Fluid shear stress is one of the most important mechanical forces acting upon vascular endothelium, because of its location at the interface between the bloodstream and vascular wall. Recent evidence indicates that several intracellular signaling events are stimulated in endothelial cells in response to shear stress. Through these events, shear stress modulates endothelial cell function and vascular structure, but the molecular basis of shear stress mechanotransduction remains to be elucidated. In our research we have focused on three temporal signal responses to shear stress: (1) production of nitric oxide (NO) as an immediate response; (2) activation of extracellular-regulated kinases (ERK1/2; p44/p42 mitogen-activated protein (MAP) kinases) as a rapid response, and (3) tyrosine phosphorylation of focal adhesion kinase (FAK) as a sustained response. In terms of vessel biology, NO production, and ERK1/2 and FAK activation seem to be correlated with vascular homeostasis, gene expression and cytoskeletal rearrangement, respectively. In this review, we discuss the mechanisms that establish the temporal order of shear stress-stimulated responses based on a hierarchy for assembly of signal transduction molecules at the cell plasma membrane.

Asunto(s)

Endotelio Vascular/fisiología , Proteínas Quinasas Activadas por Mitógenos , Transducción de Señal , Animales , Proteínas Quinasas Dependientes de Calcio-Calmodulina/metabolismo , Moléculas de Adhesión Celular/metabolismo , Endotelio Vascular/citología , Quinasa 1 de Adhesión Focal , Proteína-Tirosina Quinasas de Adhesión Focal , Humanos , Proteína Quinasa 1 Activada por Mitógenos , Proteína Quinasa 3 Activada por Mitógenos , Óxido Nítrico/biosíntesis , Fosforilación , Proteínas Tirosina Quinasas/metabolismo , Estrés Mecánico , Tirosina/metabolismo

RESUMEN

We propose a model for signaling events induced by fluid shear stress that incorporates many of the features discussed in this paper (FIG. 4). First, heterotrimeric G-proteins, as well as a small G-proteins, are activated by flow. Indeed, a G protein appears to be required for ERK1/2 activation by flow because ERK1/2 activation is completely inhibited by GDP-beta S. Then, flow activates phospholipase C and generates IP3 and diacylglycerol (DG). IP3 releases Ca2+ from internal Ca2+ stores via IP3 receptor and DG activates PKC. Nollert and colleagues have shown that flow activates PLC and increases IP3. It is possible that several different PKC isozymes are activated by flow including both Ca(2+)-dependent and Ca(2+)-independent isozymes. These different isozymes may have specific downstream substrates. For example, PKC-epsilon may be involved in activation of ERK1/2, while the PKC isozyme responsible for activation of JNK remains unknown. It is also possible that these PKC isozymes may be important in gene transcription events. For example, PKC-zeta has been suggested to be involved in NF-kappa B-mediated gene transcription. Longer term changes in endothelial cell morphology and structure are likely to involve separate kinases. Important candidates for these changes include members of the c-Src and FAK families. c-Src is now considered to be a component of the focal adhesion complex and regulate focal adhesion formation and/or cytoskeletal rearrangement. Recently, stretch, another mechanostress, has been shown to activate c-Src in fetal rat lung cells. It has been clarified that ERK1/2 and JNK are regulated by the small G-proteins, Ras and Rac/Cdc42H, respectively, and their effectors in parallel with each other. Rac and Rho are also thought to be involved in membrane ruffling and/or cytoskeletal rearrangement. Fluid shear stress causes stress fiber formation and focal adhesion rearrangement. Recent study by Malek and Izumo suggested the importance of microtubules in shear stress-induced morphological change and actin stress fiber formation. It is clear that the focal adhesion complex plays an important role in shear stress-induced signal and it is interesting to speculate that shear stress-induced signaling has cross-talk with signaling induced by integrins. As a general model we propose that the integration between the rapid events stimulated by shear stress and the longer term events is mediated by tyrosine kinases that serve to regulate these multiple signal transduction pathways.

Asunto(s)

Endotelio Vascular/fisiopatología , Transducción de Señal , Animales , Arteriosclerosis/patología , Arteriosclerosis/fisiopatología , Endotelio Vascular/patología , Humanos , Estrés Mecánico

RESUMEN

Endothelial cells release nitric oxide (NO) more potently in response to increased shear stress than to agonists which elevate intracellular free calcium concentration ([Ca2+]i). To determine mechanistic differences in the regulation of endothelial constitutive NO synthase (ecNOS), we measured NO production by bovine aortic endothelial cells exposed to shear stress in a laminar flow chamber or treated with Ca2+ ionophores in static culture. The kinetics of cumulative NO production varied strikingly: shear stress (25 dyne/cm2) stimulated a biphasic increase over control that was 13-fold at 60 minutes, whereas raising [Ca2+]i caused a monophasic 6-fold increase. We hypothesized that activation of a protein kinase cascade mediates the early phase of flow-dependent NO production. Immunoprecipitation of ecNOS showed a 210% increase in phosphorylation 1 minute after flow initiation, whereas there was no significant increase after Ca2+ ionophore treatment. Although ecNOS was not tyrosine-phosphorylated, the early phase of flow-dependent NO production was blocked by genistein, an inhibitor of tyrosine kinases. To determine the Ca2+ requirement for flow-dependent NO production, we measured [Ca2+]i with a novel flow-step protocol. [Ca2+]i increased with the onset of shear stress, but not after a step increase. However, the step increase in shear stress was associated with a potent biphasic increase in NO production rate and ecNOS phosphorylation. These studies demonstrate that shear stress can increase NO production in the absence of increased [Ca2+]i, and they suggest that phosphorylation of ecNOS may importantly modulate its activity during the imposition of increased shear stress.

Asunto(s)

Endotelio Vascular/metabolismo , Óxido Nítrico Sintasa/metabolismo , Animales , Calcio/agonistas , Calcio/metabolismo , Bovinos , Células Cultivadas , Endotelio Vascular/citología , Inhibidores Enzimáticos/farmacología , Genisteína , Membranas Intracelulares/metabolismo , Isoflavonas/farmacología , Cinética , Óxido Nítrico/antagonistas & inhibidores , Óxido Nítrico/biosíntesis , Concentración Osmolar , Fosforilación , Estrés Mecánico

RESUMEN

The mechanisms responsible for altered vascular smooth muscle cell (VSMC) function in hypertension remain unknown. In the spontaneously hypertensive rat (SHR) model of genetic hypertension, there are multiple abnormalities in VSMC function, including increased growth, Na(+)-H+ exchange, and increased signal transduction by protein kinase C. The family of kinases termed mitogen-activated protein (MAP) kinases has recently been shown to be essential mediators of growth factor signal transduction. In the present study, alterations in MAP kinase function in the hypertensive phenotype were investigated using early-passage SHR and Wistar-Kyoto (WKY) VSMCs stimulated with angiotensin II (Ang II, 100 nmol/L) or platelet-derived growth factor-BB (PDGF-BB, 10 ng/mL). MAP kinase activity was measured by in-gel kinase assays and Western blot analysis. Two differences between SHR and WKY rats were observed for Ang II-mediated MAP kinase activation: (1) Inactivation after Ang II stimulation was more rapid in SHR than WKY VSMCs. (2) Activity in SHR VSMCs showed a greater dependence on Ca2+ mobilization, since chelation of intracellular Ca2+ with BAPTA inhibited maximal activity by 95% in SHR VSMCs but by only 50% in WKY VSMCs. In contrast to the results with Ang II, no differences in PDGF-stimulated MAP kinase activity were observed. These findings establish activation of MAP kinase by Ang II as a feature that distinguishes SHR VSMCs from WKY VSMCs and suggest that differences in regulation of MAP kinase signaling may alter cellular events that are increased in the SHR genetic model of hypertension.

Asunto(s)

Proteínas Quinasas Dependientes de Calcio-Calmodulina/metabolismo , Calcio/fisiología , Proteínas de Ciclo Celular , Hipertensión/enzimología , Músculo Liso Vascular/enzimología , Fosfoproteínas Fosfatasas , Transducción de Señal , Angiotensina II/farmacología , Animales , Células Cultivadas , Fosfatasa 1 de Especificidad Dual , Activación Enzimática , Proteínas Inmediatas-Precoces/biosíntesis , Fosforilación , Factor de Crecimiento Derivado de Plaquetas/farmacología , Proteína Quinasa C/fisiología , Proteína Fosfatasa 1 , Proteínas Tirosina Fosfatasas/biosíntesis , Ratas , Ratas Endogámicas SHR , Ratas Endogámicas WKY

RESUMEN

A case of angina bullosa haemorrhagica is reported in which blood blisters appeared during crown preparation. The aetiology, differential diagnosis and management are discussed. Practitioners should be aware of this disorder and take precautions to minimise trauma during operative procedures.

Asunto(s)

Vesícula/etiología , Coronas/efectos adversos , Preparación de la Cavidad Dental/efectos adversos , Mucosa Bucal/lesiones , Hemorragia Bucal/etiología , Adulto , Diagnóstico Diferencial , Femenino , Estudios de Seguimiento , Humanos , Enfermedades de los Labios/etiología , Úlcera/etiología

RESUMEN

Fluid shear stress regulates endothelial cell function, but the signal transduction mechanisms involved in mechanotransduction remain unclear. Recent findings demonstrate that several intracellular kinases are activated by mechanical forces. In particular, members of the mitogen-activated protein (MAP) kinase family are stimulated by hyperosmolarity, stretch, and stress such as heat shock. We propose a model for mechanotransduction in endothelial cells involving calcium-dependent and calcium-independent protein kinase pathways. The calcium-dependent pathway involves activation of phospholipase C, hydrolysis of phosphatidylinositol 4,5-bisphosphate (PIP2), increases in intracellular calcium and stimulation of kinases such as calcium-calmodulin and C kinases (PKC). The calcium-independent pathway involves activation of a small GTP-binding protein and stimulation of calcium-independent PKC and MAP kinases. The calcium-dependent pathway mediates the rapid, transient response to fluid shear stress including activation of nitric oxide synthase (NOS) and ion transport. In contrast, the calcium-independent pathway mediates a slower response including the sustained activation of NOS and changes in cell morphology and gene expression. We propose that focal adhesion complexes link the calcium-dependent and calcium-independent pathways by regulating activity of phosphatidylinositol 4-phosphate (PIP) 5-kinase (which regulates PIP2 levels) and p125 focal adhesion kinase (FAK, which phosphorylates paxillin and interacts with cytoskeletal proteins). This model predicts that dynamic interactions between integrin molecules present in focal adhesion complexes and membrane events involved in mechanotransduction will be integrated by calcium-dependent and calcium-independent kinases to generate intracellular signals involved in the endothelial cell response to flow.

Asunto(s)

Calcio/fisiología , Endotelio Vascular/fisiología , Proteínas Quinasas/fisiología , Transducción de Señal/fisiología , Calmodulina/fisiología , Moléculas de Adhesión Celular/fisiología , Proteínas del Citoesqueleto/fisiología , Endotelio Vascular/citología , Quinasa 1 de Adhesión Focal , Proteína-Tirosina Quinasas de Adhesión Focal , Proteínas de Unión al GTP/fisiología , Expresión Génica , Humanos , Integrinas/fisiología , Transporte Iónico , Modelos Cardiovasculares , Óxido Nítrico Sintasa/fisiología , Concentración Osmolar , Paxillin , Fosfatidilinositol 4,5-Difosfato , Fosfatos de Fosfatidilinositol/fisiología , Fosfoproteínas/fisiología , Proteína Quinasa C/fisiología , Proteínas Tirosina Quinasas/fisiología , Receptor de Insulina/fisiología , Reología , Estrés Mecánico , Estrés Fisiológico/fisiopatología , Fosfolipasas de Tipo C/fisiología

Asunto(s)

Anestesia Dental/estadística & datos numéricos , Anestesia General/estadística & datos numéricos , Anestesia Intravenosa/estadística & datos numéricos , Odontología General , Recolección de Datos/métodos , Inglaterra , Humanos , Teléfono , Población Urbana

RESUMEN

Angiotensin converting enzyme (ACE) activity contributes to the vascular response to injury because ACE inhibition limits neointima formation in rat carotid arteries after balloon injury. To investigate the mechanisms by which ACE may contribute to vascular smooth muscle cell (VSMC) proliferation, we studied expression of ACE in vivo after injury and in vitro after growth factor stimulation. ACE activity 14 d after injury was increased 3.6-fold in the injured vessel. ACE expression, measured by immunohistochemistry, became apparent at 7 d in the neointima and at 14 d was primarily in the most luminal neointimal cells. To characterize hormones that induce ACE in vivo, cultured VSMC were exposed to steroids and growth factors. Among steroids, only glucocorticoids stimulated ACE expression with an 8.0 +/- 2.1-fold increase in activity and a 6.5-fold increase in mRNA (30 nM dexamethasone for 72 h). Among growth factors tested, only fibroblast growth factor (FGF) stimulated ACE expression (4.2 +/- 0.7-fold increase in activity and 1.6-fold increase in mRNA in response to 10 ng/ml FGF for 24 h). Dexamethasone and FGF were synergistic at the indicated concentrations inducing 50.6 +/- 12.4-fold and 32.5-fold increases in activity and mRNA expression, respectively. In addition, when porcine iliac arteries were transfected with recombinant FGF-1 (in the absence of injury), ACE expression increased in neointimal VSMC, to the same extent as injured, nontransfected arteries. The data suggest a temporal sequence for the response to injury in which FGF induces ACE, ACE generates angiotensin II, and angiotensin II stimulates VSMC growth in concert with FGF.

Asunto(s)

Arterias/efectos de los fármacos , Factores de Crecimiento de Fibroblastos/farmacología , Regulación de la Expresión Génica , Músculo Liso Vascular/efectos de los fármacos , Peptidil-Dipeptidasa A/biosíntesis , Animales , Aorta/citología , Aorta/patología , Arterias/citología , Arterias/patología , Arterias Carótidas/efectos de los fármacos , Arterias Carótidas/patología , Células Cultivadas , Relación Dosis-Respuesta a Droga , Inducción Enzimática , Factores de Crecimiento de Fibroblastos/genética , Glucocorticoides , Masculino , Músculo Liso Vascular/enzimología , Músculo Liso Vascular/patología , Ratas , Proteínas Recombinantes/farmacología , Porcinos , Transfección

RESUMEN

The vascular tree is a highly specialized organ that has developed a complex and highly orchestrated mechanism of response to injury and stress. After PTCA-like injury many of these mechanisms are activated to maintain vessel integrity. Similar but clearly different growth mechanisms are activated by hypertension and hemodynamic stress. In this light, restenosis is merely a reparative response that has gone on too long or to a greater extent than necessary. The number of growth factors that affect this system is enormous, and their temporal and spatial distribution suggests that therapy targeted to any single factor is unlikely to be successful. In contrast, therapies directed at common mediators such as extracellular matrix and downstream cellular effectors may be more effective. Increasing knowledge of these interactions should point the way to new therapies based on cell-cell and cell-matrix interactions that are tissue specific and focused in time and that take advantage of the common mechanisms by which vessels normally adapt to stress.

Asunto(s)

Vasos Sanguíneos/fisiología , Sustancias de Crecimiento/fisiología , Animales , Endotelio Vascular/fisiología , Factores de Crecimiento de Fibroblastos/fisiología , Humanos , Óxido Nítrico/fisiología , Factor de Crecimiento Transformador beta/fisiología