RESUMEN
Gastric disorders are increasingly prevalent, but reliable noninvasive tools to objectively assess gastric function are lacking. Body-surface gastric mapping (BSGM) is a noninvasive method for the detection of gastric electrophysiological features, which are correlated with symptoms in patients with gastroparesis and functional dyspepsia. Previous studies have validated the relationship between serosal and cutaneous recordings from limited number of channels. This study aimed to comprehensively evaluate the basis of BSGM from 64 cutaneous channels and reliably identify spatial biomarkers associated with slow-wave dysrhythmias. High-resolution electrode arrays were placed to simultaneously capture slow waves from the gastric serosa (32 × 6 electrodes at 4 mm spacing) and epigastrium (8 × 8 electrodes at 20 mm spacing) in 14 porcine subjects. BSGM signals were processed based on a combination of wavelet and phase information analyses. A total of 1,185 individual cycles of slow waves were assessed, out of which 897 (76%) were classified as normal antegrade waves, occurring in 10 (71%) subjects studied. BSGM accurately detected the underlying slow wave in terms of frequency (r = 0.99, P = 0.43) as well as the direction of propagation (P = 0.41, F-measure: 0.92). In addition, the cycle-by-cycle match between BSGM and transitions of gastric slow wave dysrhythmias was demonstrated. These results validate BSGM as a suitable method for noninvasively and accurately detecting gastric slow-wave spatiotemporal profiles from the body surface.NEW & NOTEWORTHY Gastric dysfunctions are associated with abnormalities in the gastric bioelectrical slow waves. Noninvasive detection of gastric slow waves from the body surface can be achieved through multichannel, high-resolution, body-surface gastric mapping (BSGM). BSGM matched the spatiotemporal characteristics of gastric slow waves recorded directly and simultaneously from the serosal surface of the stomach. Abnormal gastric slow waves, such as retrograde propagation, ectopic pacemaker, and colliding wavefronts can be detected by changes in the phase of BSGM.
Asunto(s)
Gastroparesia , Estómago , Animales , Electrodos , Fenómenos Electrofisiológicos , Motilidad Gastrointestinal/fisiología , Humanos , Membrana Serosa/fisiología , Estómago/fisiología , PorcinosRESUMEN
Slow waves play a central role in coordinating gastric motor activity. High-resolution mapping of extracellular potentials from the stomach provides spatiotemporal detail on normal and dysrhythmic slow-wave patterns. All mapping studies to date have focused exclusively on tissue activation; however, the recovery phase contains vital information on repolarization heterogeneity, the excitable gap, and refractory tail interactions but has not been investigated. Here, we report a method to identify the recovery phase in slow-wave mapping data. We first developed a mathematical model of unipolar extracellular potentials that result from slow-wave propagation. These simulations showed that tissue repolarization in such a signal is defined by the steepest upstroke beyond the activation phase (activation was defined by accepted convention as the steepest downstroke). Next, we mapped slow-wave propagation in anesthetized pigs by recording unipolar extracellular potentials from a high-resolution array of electrodes on the serosal surface. Following the simulation result, a wavelet transform technique was applied to detect repolarization in each signal by finding the maximum positive slope beyond activation. Activation-recovery (ARi) and recovery-activation (RAi) intervals were then computed. We hypothesized that these measurements of recovery profile would differ for slow waves recorded during normal and spatially dysrhythmic propagation. We found that the ARi of normal activity was greater than dysrhythmic activity (5.1 ± 0.8 vs. 3.8 ± 0.7 s; P < 0.05), whereas RAi was lower (9.7 ± 1.3 vs. 12.2 ± 2.5 s; P < 0.05). During normal propagation, RAi and ARi were linearly related with negative unit slope indicating entrainment of the entire mapped region. This relationship was weakened during dysrhythmia (slope: -0.96 ± 0.2 vs -0.71 ± 0.3; P < 0.05).NEW & NOTEWORTHY The theoretical basis of the extracellular gastric slow-wave recovery phase was defined using mathematical modeling. A novel technique utilizing the wavelet transform was developed and validated to detect the extracellular slow-wave recovery phase. In dysrhythmic wavefronts, the activation-to-recovery interval (ARi) was shorter and recovery-to-activation interval (RAi) was longer compared with normal wavefronts. During normal activation, RAi vs. ARi had a slope of -1, whereas the weakening of the slope indicated a dysrhythmic propagation.
Asunto(s)
Fenómenos Electrofisiológicos/fisiología , Motilidad Gastrointestinal/fisiología , Modelos Biológicos , Músculo Liso/fisiología , Membrana Serosa/fisiología , Estómago/fisiología , Animales , Electromiografía , Membrana Serosa/citología , PorcinosRESUMEN
BACKGROUND: Gastric motility is coordinated by bioelectrical slow waves, and gastric dysrhythmias are reported in motility disorders. High-resolution (HR) mapping has advanced the accurate assessment of gastric dysrhythmias, offering promise as a diagnostic technique. However, HR mapping has been restricted to invasive surgical serosal access. This study investigates the feasibility of HR mapping from the gastric mucosal surface. METHODS: Experiments were conducted in vivo in 14 weaner pigs. Reference serosal recordings were performed with flexible-printed-circuit (FPC) arrays (128-192 electrodes). Mucosal recordings were performed by two methods: (i) FPC array aligned directly opposite the serosal array, and (ii) cardiac mapping catheter modified for gastric mucosal recordings. Slow-wave propagation and morphology characteristics were quantified and compared between simultaneous serosal and mucosal recordings. KEY RESULTS: Slow-wave activity was consistently recorded from the mucosal surface from both electrode arrays. Mucosally recorded slow-wave propagation was consistent with reference serosal activation pattern, frequency (P≥.3), and velocity (P≥.4). However, mucosally recorded slow-wave morphology exhibited reduced amplitude (65-72% reduced, P<.001) and wider downstroke width (18-31% wider, P≤.02), compared to serosal data. Dysrhythmias were successfully mapped and classified from the mucosal surface, accorded with serosal data, and were consistent with known dysrhythmic mechanisms in the porcine model. CONCLUSIONS & INFERENCES: High-resolution gastric electrical mapping was achieved from the mucosal surface, and demonstrated consistent propagation characteristics with serosal data. However, mucosal signal morphology was attenuated, demonstrating necessity for optimized electrode designs and analytical algorithms. This study demonstrates feasibility of endoscopic HR mapping, providing a foundation for advancement of minimally invasive spatiotemporal gastric mapping as a clinical and scientific tool.
Asunto(s)
Electrofisiología/métodos , Motilidad Gastrointestinal , Membrana Mucosa/fisiología , Membrana Serosa/fisiología , Animales , Electrodos , Fenómenos Electrofisiológicos , Electrofisiología/instrumentación , Femenino , Procesamiento de Señales Asistido por Computador , PorcinosRESUMEN
Unlike passive rupture of the human chorioamnion at birth, the insect extraembryonic (EE) tissues - the amnion and serosa - actively rupture and withdraw in late embryogenesis. Withdrawal is essential for development and has been a morphogenetic puzzle. Here, we use new fluorescent transgenic lines in the beetle Tribolium castaneum to show that the EE tissues dynamically form a basal-basal epithelial bilayer, contradicting the previous hypothesis of EE intercalation. We find that the EE tissues repeatedly detach and reattach throughout development and have distinct roles. Quantitative live imaging analyses show that the amnion initiates EE rupture in a specialized anterior-ventral cap. RNAi phenotypes demonstrate that the serosa contracts autonomously. Thus, apposition in a bilayer enables the amnion as 'initiator' to coordinate with the serosa as 'driver' to achieve withdrawal. This EE strategy may reflect evolutionary changes within the holometabolous insects and serves as a model to study interactions between developing epithelia.
Asunto(s)
Membranas Extraembrionarias/fisiología , Tribolium/fisiología , Animales , Epitelio/fisiología , Imagen Óptica , Reproducción , Membrana Serosa/fisiologíaRESUMEN
The subserous space is a large, anatomically continuous potential space that interconnects the chest, abdomen, and pelvis. The subserous space is formed from areolar and adipose tissue, and contains branches of the vascular, lymphatic, and nervous systems. As such, it provides one large continuous space in which many disease processes can spread between the chest, abdomen, and the pelvis.
Asunto(s)
Cavidad Abdominal/fisiopatología , Pelvis/fisiopatología , Peritoneo/fisiopatología , Membrana Serosa/fisiopatología , Cavidad Torácica/fisiopatología , Cavidad Abdominal/anatomía & histología , Cavidad Abdominal/diagnóstico por imagen , Cavidad Abdominal/fisiología , Humanos , Pelvis/anatomía & histología , Pelvis/diagnóstico por imagen , Pelvis/fisiología , Peritoneo/anatomía & histología , Peritoneo/diagnóstico por imagen , Peritoneo/fisiología , Radiografía Torácica , Membrana Serosa/anatomía & histología , Membrana Serosa/diagnóstico por imagen , Membrana Serosa/fisiología , Cavidad Torácica/anatomía & histología , Cavidad Torácica/fisiologíaRESUMEN
BACKGROUND: Extracellular recordings are used to define gastric slow wave propagation. Signal filtering is a key step in the analysis and interpretation of extracellular slow wave data; however, there is controversy and uncertainty regarding the appropriate filtering settings. This study investigated the effect of various standard filters on the morphology and measurement of extracellular gastric slow waves. METHODS: Experimental extracellular gastric slow waves were recorded from the serosal surface of the stomach from pigs and humans. Four digital filters: finite impulse response filter (0.05-1 Hz); Savitzky-Golay filter (0-1.98 Hz); Bessel filter (2-100 Hz); and Butterworth filter (5-100 Hz); were applied on extracellular gastric slow wave signals to compare the changes temporally (morphology of the signal) and spectrally (signals in the frequency domain). KEY RESULTS: The extracellular slow wave activity is represented in the frequency domain by a dominant frequency and its associated harmonics in diminishing power. Optimal filters apply cutoff frequencies consistent with the dominant slow wave frequency (3-5 cpm) and main harmonics (up to ≈ 2 Hz). Applying filters with cutoff frequencies above or below the dominant and harmonic frequencies was found to distort or eliminate slow wave signal content. CONCLUSIONS & INFERENCES: Investigators must be cognizant of these optimal filtering practices when detecting, analyzing, and interpreting extracellular slow wave recordings. The use of frequency domain analysis is important for identifying the dominant and harmonics of the signal of interest. Capturing the dominant frequency and major harmonics of slow wave is crucial for accurate representation of slow wave activity in the time domain. Standardized filter settings should be determined.
Asunto(s)
Electrofisiología/métodos , Motilidad Gastrointestinal/fisiología , Procesamiento de Señales Asistido por Computador , Animales , Humanos , Membrana Serosa/fisiologíaRESUMEN
Obesity is one of the most prevalent health problems in the United States. Current therapeutic strategies for the treatment of obesity are unsatisfactory. We hypothesized the use of colon electrical stimulation (CES) to treat obesity by inhibiting upper gastrointestinal motility. In this preliminary study, we aimed at studying the effects of CES on gastric emptying of solid, intestinal motility, and food intake in dogs. Six dogs, equipped with serosal colon electrodes and a jejunal cannula, were randomly assigned to receive sham-CES or CES during the assessment of: (i) gastric emptying of solids, (ii) postprandial intestinal motility, (iii) autonomic functions, and (iv) food intake. We found that (i) CES delayed gastric emptying of solids by 77%. Guanethidine partially blocked the inhibitory effect of CES on solid gastric emptying; (ii) CES significantly reduced intestinal contractility and the effect lasted throughout the recovery period; (iii) CES decreased vagal activity in both fasting and fed states, increased the sympathovagal balance and marginally increased sympathetic activity in the fasting state; (iv) CES resulted in a reduction of 61% in food intake. CES reduces food intake in healthy dogs and the anorexigenic effect may be attributed to its inhibitory effects on gastric emptying and intestinal motility, mediated via the autonomic mechanisms. Further studies are warranted to investigate the therapeutic potential of CES for obesity.
Asunto(s)
Regulación del Apetito , Colon/fisiopatología , Terapia por Estimulación Eléctrica , Motilidad Gastrointestinal , Obesidad/terapia , Antagonistas Adrenérgicos/farmacología , Animales , Sistema Nervioso Autónomo/efectos de los fármacos , Ciego/inervación , Ciego/fisiología , Colon/efectos de los fármacos , Colon/inervación , Colon/fisiología , Perros , Estimulación Eléctrica/métodos , Femenino , Vaciamiento Gástrico/efectos de los fármacos , Motilidad Gastrointestinal/efectos de los fármacos , Tránsito Gastrointestinal , Guanetidina/farmacología , Obesidad/fisiopatología , Periodo Posprandial , Distribución Aleatoria , Membrana Serosa/inervación , Membrana Serosa/fisiología , Sistema Nervioso Simpático/fisiología , Nervio Vago/fisiologíaRESUMEN
High resolution electrical mapping of slow waves on the stomach serosa has improved our understanding of gastric electrical activity in normal and diseased states. In order to assess the signals acquired from high resolution mapping, a robust framework is required. Our framework is semi-automated and allows for rapid processing, analysis and interpretation of slow waves via qualitative and quantitative measures including isochronal activation time mapping, and velocity and amplitude mapping. Noise removal techniques were validated for raw recorded signals, where three filters were evaluated for baseline drift removal and three filters for removal of high frequency interference. For baseline drift removal, the Gaussian moving median filter was most effective, while for eliminating high frequency interference the Savitzky Golay filter was the most effective. Methods for assessing slow wave velocity and amplitude were investigated. To estimate slow wave velocity, a finite difference approach with interpolation and smoothing was used. To evaluate the slow wave amplitude and width, a peak and trough method based on Savitzky Golay derivative filters was used. Together, these methods constitute a significantly improved framework for analyzing gastric high resolution mapping data.
Asunto(s)
Algoritmos , Artefactos , Electromiografía/métodos , Complejo Mioeléctrico Migratorio/fisiología , Membrana Serosa/fisiología , Procesamiento de Señales Asistido por Computador , Estómago/fisiología , Diagnóstico por Computador/métodos , Humanos , Reproducibilidad de los Resultados , Sensibilidad y Especificidad , Relación Señal-RuidoRESUMEN
The functions of the gastrointestinal (GI) tract include digestion, absorption, excretion, and protection. In this review, we focus on the electrical activity of the stomach and small intestine, which underlies the motility of these organs, and where the most detailed systems descriptions and computational models have been based to date. Much of this discussion is also applicable to the rest of the GI tract. This review covers four major spatial scales: cell, tissue, organ, and torso, and discusses the methods of investigation and the challenges associated with each. We begin by describing the origin of the electrical activity in the interstitial cells of Cajal, and its spread to smooth muscle cells. The spread of electrical activity through the stomach and small intestine is then described, followed by the resultant electrical and magnetic activity that may be recorded on the body surface. A number of common and highly symptomatic GI conditions involve abnormal electrical and/or motor activity, which are often termed functional disorders. In the last section of this review we address approaches being used to characterize and diagnose abnormalities in the electrical activity and how these might be applied in the clinical setting. The understanding of electrophysiology and motility of the GI system remains a challenging field, and the review discusses how biophysically based mathematical models can help to bridge gaps in our current knowledge, through integration of otherwise separate concepts.
Asunto(s)
Electrofisiología , Tracto Gastrointestinal/fisiología , Animales , Electrofisiología/métodos , Motilidad Gastrointestinal/fisiología , Tracto Gastrointestinal/citología , Tracto Gastrointestinal/metabolismo , Humanos , Mucosa Intestinal/citología , Mucosa Intestinal/metabolismo , Mucosa Intestinal/fisiología , Modelos Biológicos , Músculo Liso/fisiología , Membrana Serosa/fisiología , Estómago/fisiologíaRESUMEN
Cottonseed (Gossypium sp.) meals are protein rich and inexpensive, but the presence of the polyphenolic dialdehyde, gossypol, is responsible of many toxic effects in animals including fishes. Recently an effect on the transepithelial ion transport in rat colon has been demonstrated. In this study we investigated the effect of gossypol on the transepithelial electrical parameters of the isolated intestine of seawater adapted eel, Anguilla anguilla, by employing a Ussing chamber technique. We showed that the addition of gossypol to the perfusion media reduced short circuit current (I(sc)), a measure of Cl- active absorption in this tissue, and increased tissue conductance (g(t)). The observation that the effect of gossypol on both I(sc) and g(t) was modified by the pretreatment with TFP, a calmodulin inhibitor, suggests that the substance acts via a Ca2+ calmodulin pathway and excludes the possibility that the observed effects were due to a cytotoxic action. In addition, experiments performed in the presence of verapamil suggest that the polyphenolic pigment increases Ca2+ influx. It is likely that gossypol stimulates a basolateral quinine sensitive K+ conductance producing a K+ flux in absorptive direction that explains the reduction of I(sc). In addition dilution potential experiments showed that the polyphenolic aldehyde increases the anion conductance of the paracellular pathway. In conclusion our study suggests that gossypol alters ion transport in eel intestine by acting on both transcellular and paracellular pathways. Since the intestine is an important organ for maintaining the water and ion balance in seawater adapted fish, it is conceivable that gossypol could impair the ability of the animals to adapt to the environment.
Asunto(s)
Adaptación Fisiológica/efectos de los fármacos , Anguilla/fisiología , Gosipol/farmacología , Intestinos/efectos de los fármacos , Intestinos/fisiología , Transporte Iónico/efectos de los fármacos , Agua de Mar , Ácido 4-Acetamido-4'-isotiocianatostilbeno-2,2'-disulfónico/farmacología , Animales , Tampones (Química) , Calcio/farmacología , Conductividad Eléctrica , Células Epiteliales/efectos de los fármacos , Células Epiteliales/fisiología , Gliburida/farmacología , Técnicas In Vitro , Activación del Canal Iónico/efectos de los fármacos , Membrana Mucosa/efectos de los fármacos , Membrana Mucosa/fisiología , Nitrobenzoatos/farmacología , Perfusión , Quinina/farmacología , Membrana Serosa/efectos de los fármacos , Membrana Serosa/fisiologíaRESUMEN
Mesothelia comprise the epithelial covering of coelomic organs and line the cavities in which they are housed. Mesothelia contribute to the vasculature of the heart and the intestinal tract by developmental processes of epithelial-mesenchymal transition (EMT), migration, and differentiation into endothelial cells, vascular smooth muscle cells, and pericytes. Here, we establish a novel in vitro system to analyze the differentiative potential of mesothelia. Using explants from serosal mesothelium (the mesothelial covering of the gut), we demonstrate that much of the developmental program observed in embryonic mesothelia is retained in the adult structure. Namely, processes of epithelial spreading, EMT, and differentiation into smooth muscle cells from these cells are observed. Interestingly, we were unable to stimulate endothelial cell differentiation using serum or various signaling factors. Taken together, these data reveal that differentiated serosal cells retain vasculogenic potential and provide a generalizable model for future studies on the developmental and differentiative capacity of the mesothelial cell type.
Asunto(s)
Diferenciación Celular , Células Epiteliales/citología , Músculo Liso Vascular/citología , Membrana Serosa/citología , Actinas/metabolismo , Animales , Becaplermina , Vasos Sanguíneos , Células Cultivadas , Desmina/metabolismo , Endotelio Vascular/citología , Endotelio Vascular/metabolismo , Epitelio/fisiología , Factores de Crecimiento de Fibroblastos/metabolismo , Queratinas/metabolismo , Ratones , Músculo Liso Vascular/metabolismo , Miosinas/metabolismo , Molécula-1 de Adhesión Celular Endotelial de Plaqueta/metabolismo , Factor de Crecimiento Derivado de Plaquetas/metabolismo , Proteínas Proto-Oncogénicas c-sis , Membrana Serosa/fisiología , Receptor 2 de Factores de Crecimiento Endotelial Vascular/metabolismo , Proteínas WT1/metabolismoRESUMEN
Bichat first described the mesothelium in 1827 but despite its early discovery, it has only been in recent years that its importance both in health and disease has been realised. One area still poorly understood is that of the mechanisms regulating mesothelial repair. Mesothelial cells are derived from the mesoderm but express many epithelial characteristics. However, mesothelium does not heal in the same way as other epithelial-like cells. Epithelium heals by centripetal migration, with cells at the edge of the wound proliferating and migrating into the injured area. Hertzler in 1919 noted that both large and small peritoneal injuries healed within the same time frame, concluding that the mesothelium could not heal solely by centripetal migration. The exact mechanisms involved in mesothelial regeneration following injury are controversial with a number of proposals suggested to explain the origin of the regenerating cells. This review will examine these proposals and give some insights into the likely mechanisms involved.
Asunto(s)
Epitelio/fisiología , Peritoneo/fisiología , Regeneración/fisiología , Cicatrización de Heridas/fisiología , Animales , Recuento de Células , Diferenciación Celular , División Celular , Células Cultivadas , Epitelio/trasplante , Humanos , Peritoneo/trasplante , Membrana Serosa/fisiologíaRESUMEN
The embryo of Toxoneuron nigriceps (Hymenoptera, Braconidae) is surrounded by an extraembryonic membrane, which, at hatching, releases teratocytes and gives rise to a cell layer embedding the body of the 1st instar larva. This cell layer was studied at different developmental times, from soon after hatching up to the first larval moult, in order to elucidate its ultrastructural, immunocytochemical and physiological function. The persisting "larval serosa" shows a striking structural and functional complexity: it is a multifunctional barrier with protective properties, limits the passage of macromolecules and it is actively involved in the enzymatic processing and uptake of nutrients. The reported results emphasizes the important role that the embryo-derived host regulation factors may have in parasitism success in Hymenoptera koinobionts.
Asunto(s)
Larva/fisiología , Avispas/fisiología , Fenómenos Fisiológicos Nutricionales de los Animales , Animales , Membranas Extraembrionarias/fisiología , Membranas Extraembrionarias/ultraestructura , Interacciones Huésped-Parásitos/fisiología , Larva/ultraestructura , Permeabilidad , Membrana Serosa/fisiología , Membrana Serosa/ultraestructura , Absorción Cutánea/fisiología , Avispas/ultraestructuraRESUMEN
Unlike most Hox cluster genes, with their canonical role in anterior-posterior patterning of the embryo, the Hox3 orthologue of insects has diverged. Here, we investigate the zen orthologue in Oncopeltus fasciatus (Hemiptera:Heteroptera). As in other insects, the Of-zen gene is expressed extraembryonically, and RNA interference (RNAi) experiments demonstrate that it is functionally required in this domain for the proper occurrence of katatrepsis, the phase of embryonic movements by which the embryo emerges from the yolk and adjusts its orientation within the egg. After RNAi knockdown of Of-zen, katatrepsis does not occur, causing embryos to complete development inside out. However, not all aspects of expression and function are conserved compared to grasshopper, beetle, and fly orthologues. Of-zen is not expressed in the extraembryonic tissue until relatively late, suggesting it is not involved in tissue specification. Within the extraembryonic domain, Of-zen is expressed in the outer serosal membrane, but unlike orthologues, it is not detectable in the inner extraembryonic membrane, the amnion. Thus, the role of zen in the interaction of serosa, amnion, and embryo may differ between species. Of-zen is also expressed in the blastoderm, although this early expression shows no apparent correlation with defects seen by RNAi knockdown.
Asunto(s)
Heterópteros/embriología , Proteínas de Homeodominio/fisiología , Proteínas de Insectos/fisiología , Membrana Serosa/fisiología , Secuencia de Aminoácidos , Animales , Blastodermo/metabolismo , Embrión no Mamífero/patología , Embrión no Mamífero/fisiología , Heterópteros/genética , Proteínas de Homeodominio/química , Proteínas de Homeodominio/genética , Proteínas de Insectos/química , Proteínas de Insectos/genética , Datos de Secuencia Molecular , Interferencia de ARNRESUMEN
The conspicuous presence of primary cilia, a small immotile cilium present on most cell types, left researchers with little doubt of their functional relevance. Recently mechanosensitive functional significance was established and a link with the pathogenesis of polycystic kidney disease. Together these discoveries have raised the profile of this, previously considered "vestigial", organelle. Primary cilia are expressed on the apical surface of serosal mesothelium and display regional variation but are more abundant on biosynthetically active cells. Adult mesothelial cells are highly biosynthetic producing a phospholipid rich surfactant that lubricates and protects the visceral organs. The mesothelium is utilized as a semipermeable membrane during peritoneal dialysis for patients with end stage renal failure. However, little is known about the functional role of primary cilia on this highly specialized cell type. The present review, examines the significance of the primary cilium in serosal mesothelial cell biology with an emphasis on ciliary location, structure, form and function. Future research is identified and discussed in view of the emerging role cilia have in other cells and the established function of the serosal mesothelium in development, normal function, peritoneal dialysis and pathology of the serosal membranes.
Asunto(s)
Cilios/ultraestructura , Células Epiteliales/citología , Cavidad Peritoneal/citología , Membrana Serosa/citología , Animales , Diferenciación Celular , Cilios/fisiología , Células Epiteliales/fisiología , Humanos , Enfermedades Renales Poliquísticas/patología , Membrana Serosa/fisiologíaRESUMEN
Mesothelial cells form a monolayer of specialised pavement-like cells that line the body's serous cavities and internal organs. The primary function of this layer, termed the mesothelium, is to provide a slippery, non-adhesive and protective surface. However, mesothelial cells play other pivotal roles involving transport of fluid and cells across the serosal cavities, antigen presentation, inflammation and tissue repair, coagulation and fibrinolysis and tumour cell adhesion. Injury to the mesothelium triggers events leading to the migration of mesothelial cells from the edge of the lesion towards the wound centre and desquamation of cells into the serosal fluid which attach and incorporate into the regenerating mesothelium. If healing is impaired, fibrous serosal adhesions form between organs and the body wall which impede vital intrathoracic and abdominal movement. Neoplastic transformation of mesothelial cells gives rise to malignant mesothelioma, an aggressive tumour predominantly of the pleura. Although closely associated with exposure to asbestos, recent studies have implicated other factors including simian virus 40 (SV40) in its pathogenesis.
Asunto(s)
Células Epiteliales/fisiología , Epitelio/fisiología , Mesotelioma/patología , Membrana Serosa/fisiología , Animales , Transformación Celular Neoplásica , Células Epiteliales/patología , Epitelio/patología , Epitelio/ultraestructura , Humanos , Mesotelioma/etiología , Microvellosidades/ultraestructura , Modelos Biológicos , Membrana Serosa/citologíaRESUMEN
Regeneration of the mesothelium is unlike that of other epithelial-like surfaces, as healing does not occur solely by centripetal migration of cells from the wound edge. The mechanism of repair of mesothelium is controversial, but it is widely accepted, without compelling evidence, that pluripotent cells beneath the mesothelium migrate to the surface and differentiate into mesothelial cells. In this study we examined an alternative hypothesis, using in vivo cell-tracking studies, that repair involves implantation, proliferation and incorporation of free-floating mesothelial cells into the regenerating mesothelium. Cultured mesothelial cells, fibroblasts and peritoneal lavage cells were DiI- or PKH26-PCL-labelled and injected into rats immediately following mesothelial injury. Implantation of labelled cells was assessed on mesothelial imprints using confocal microscopy, and cell proliferation was determined by proliferating cell nuclear antigen immunolabelling. Incorporation of labelled cells, assessed by the formation of apical junctional complexes, was shown by confocal imaging of zonula occludens-1 protein. Labelled cultured mesothelial and peritoneal lavage cells, but not cultured fibroblasts, implanted onto the wound surface 3, 5 and 8 days after injury. These cells proliferated and incorporated into the regenerated mesothelium, as demonstrated by nuclear proliferating cell nuclear antigen staining and membrane-localised zonula occludens-1 expression, respectively. Furthermore, immunolocalisation of the mesothelial cell marker HBME-1 demonstrated that the incorporated, labelled lavage-derived cells were mesothelial cells and not macrophages as it had previously been suggested. This study has clearly shown that serosal healing involves implantation, proliferation and incorporation of free-floating mesothelial cells into the regenerating mesothelium.
Asunto(s)
Epitelio/fisiología , Compuestos Orgánicos , Membrana Serosa/fisiología , Cicatrización de Heridas , Animales , Carbocianinas/química , Células Cultivadas , Epitelio/metabolismo , Epitelio/trasplante , Técnica del Anticuerpo Fluorescente , Colorantes Fluorescentes/química , Masculino , Peritoneo/anatomía & histología , Peritoneo/citología , Ratas , Ratas Endogámicas Lew , Membrana Serosa/citología , Membrana Serosa/trasplanteRESUMEN
PURPOSE: This study investigated the effects of mucosal (urine side) and serosal (blood side) urea on the permeability properties of the in vitro mammalian urinary bladder epithelium. MATERIALS AND METHODS: The permeability properties of the rabbit urinary bladder epithelium were studied in modified Ussing chambers using electrophysiological techniques. RESULTS: Addition of two molar urea to the mucosal solution did not cause a significant change in the short circuit current (Isc, a measure of the ion transport capacity of the epithelium), or the transepithelial conductance (Gt, a measure of the ability of ions to diffuse across the epithelium). In contrast, addition of 0.5 M urea to the serosal solution caused an increase in Gt of approximately 35 microS/cm.2 as well as an increase in Isc over a 5 minute period. The site of the conductance increase by short-term serosal urea was at the apical membrane and not at the tight junctions. The urea-induced conductance completely reversed upon removal of urea, was non-selective, and the magnitude was voltage dependent. Long term serosal urea (greater than 30 minutes) resulted in an irreversible increase in transepithelial conductance. Mucosal urea altered the time course but not the magnitude of the serosal urea-induced conductance. CONCLUSIONS: The ion permeability of the mammalian urinary bladder is increased by serosal urea. At short times the increase is at the apical membrane, while at long times the increase is at the tight junctions. The presence of mucosal urea slows the loss of urothelial barrier function caused by serosal urea.
Asunto(s)
Urea/metabolismo , Vejiga Urinaria/metabolismo , Animales , Electrofisiología , Masculino , Permeabilidad , Conejos , Membrana Serosa/metabolismo , Membrana Serosa/fisiología , Vejiga Urinaria/fisiología , Urotelio/metabolismo , Urotelio/fisiologíaRESUMEN
Controversial interpretations have been given to the postprandial increase in the dominant power (amplitude) of the electrogastrogram (EGG). The aim of this study was to find an appropriate interpretation of the postprandial EGG power changes. Simultaneous serosal and cutaneous recordings of gastric myoelectrical activity were made in 11 patients with gastroparesis in the fasting state and after the ingestion of 8 oz of water. The dominant frequency and corresponding power of the recording before and after water were computed using the power spectral analysis method. It was found that the dominant frequency of the EGG was the same as that of the serosal recording in 10 patients. One patient showed a substantial amount of dysrhythmia and no obvious dominant frequency was noted. A decrease in the dominant frequency was found in these 10 patients after the ingestion of water. Tachygastria of higher than 4 cycles/min was observed in one of 11 patients both in the prewater and postwater states. Consistent changes in amplitude after a drink of water were noted in both serosal recording and EGG. Statistical analysis demonstrated that the dominant power change after water computed from the EGG was correlated with that observed in the serosal recording (r = 0.757, P = 0.007). In conclusion, exogenous stimulation, such as ingestion of water, may change the amplitude of the gastric slow wave and this change is reflected in the EGG, suggesting that the change of the slow-wave amplitude is an important contributing factor to the postprandial change in the EGG dominant power.
Asunto(s)
Ingestión de Alimentos/fisiología , Motilidad Gastrointestinal , Gastroparesia/fisiopatología , Estómago/fisiopatología , Adulto , Electrofisiología , Femenino , Humanos , Masculino , Persona de Mediana Edad , Contracción Muscular/fisiología , Músculo Liso/fisiología , Periodo Posprandial , Membrana Serosa/fisiología , Fenómenos Fisiológicos de la PielRESUMEN
The aim of this study was to derive effective pacing parameters for the entrainment of segmental intestinal myoelectrical activity. The study was performed in 12 dogs. Four pairs of electrodes were implanted on the serosa of the jejunum. Electrical stimulation of the small intestine was performed via the most proximal pair. For the slow waves within a distance of 5 cm, a complete entrainment was achieved with a pacing frequency of 1.1 times the intrinsic frequency (IF), a pulse width of 140 msec, and an amplitude of 4 mA. The time required for the entrainment was 25.6 +/- 2.7 sec. The maximum driven frequency was 1.38 +/- 0.03 IF. The percentage of the entrainment at this frequency was 44.0 +/- 3.9%. The data indicate that pacing is able to completely entrain segmental intestinal myoelectrical activity, suggesting that normalization of intestinal myoelectrical dysrhythmia is feasible with pacing.