RESUMEN
Microscale propulsion impacts a diverse array of fields ranging from biology and ecology to health applications, such as infection, fertility, drug delivery, and microsurgery. However, propulsion in such viscous drag-dominated fluid environments is highly constrained, with time-reversal and geometric symmetries ruling out entire classes of propulsion. Here, we report the spontaneous symmetry-breaking propulsion of rotating spherical microparticles within non-Newtonian fluids. While symmetry analysis suggests that propulsion is not possible along the fore-aft directions, we demonstrate the existence of two equal and opposite propulsion states along the sphere's rotation axis. We propose and experimentally corroborate a propulsion mechanism for these spherical microparticles, the simplest microswimmers to date, arising from nonlinear viscoelastic effects in rotating flows similar to the rod-climbing effect. Similar possibilities of spontaneous symmetry-breaking could be used to circumvent other restrictions on propulsion, revising notions of microrobotic design and control, drug delivery, microscale pumping, and locomotion of microorganisms.
Asunto(s)
Elasticidad , Fenómenos Magnéticos , Microesferas , Dinámicas no Lineales , Resinas Acrílicas/química , Humanos , Mucinas/química , Mucinas/ultraestructura , Reología , ViscosidadRESUMEN
The respiratory and intestinal tracts are exposed to physical and biological hazards accompanying the intake of air and food. Likewise, the vasculature is threatened by inflammation and trauma. Mucin glycoproteins and the related von Willebrand factor guard the vulnerable cell layers in these diverse systems. Colon mucins additionally house and feed the gut microbiome. Here, we present an integrated structural analysis of the intestinal mucin MUC2. Our findings reveal the shared mechanism by which complex macromolecules responsible for blood clotting, mucociliary clearance, and the intestinal mucosal barrier form protective polymers and hydrogels. Specifically, cryo-electron microscopy and crystal structures show how disulfide-rich bridges and pH-tunable interfaces control successive assembly steps in the endoplasmic reticulum and Golgi apparatus. Remarkably, a densely O-glycosylated mucin domain performs an organizational role in MUC2. The mucin assembly mechanism and its adaptation for hemostasis provide the foundation for rational manipulation of barrier function and coagulation.
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Biopolímeros/metabolismo , Mucinas/metabolismo , Factor de von Willebrand/metabolismo , Secuencia de Aminoácidos , Animales , Microscopía por Crioelectrón , Disulfuros/metabolismo , Femenino , Glicosilación , Células HEK293 , Humanos , Concentración de Iones de Hidrógeno , Ratones Endogámicos C57BL , Modelos Moleculares , Mucinas/química , Mucinas/ultraestructura , Péptidos/química , Dominios Proteicos , Multimerización de Proteína , Factor de von Willebrand/química , Factor de von Willebrand/ultraestructuraRESUMEN
Low grade appendiceal mucinous neoplasm (LAMN) is the primary source of pseudomyxoma peritonei (PMP). PMP may develop after seemingly complete resection of primary tumor by appendectomy, which is unpredictable due to lack of reliable prognostic indicators. We retrospectively reviewed 154 surgically resected LAMNs to explore if any of the macroscopic and microscopic characteristics may be associated with increasing risk of PMP development. Our major findings include: (1) As compared to those without PMP, the cases that developed PMP were more frequent to have (a) smaller luminal diameter (<1 cm) and thicker wall, separate mucin aggregations, and microscopic perforation/rupture, all suggestive of luminal mucin leakage; (b) microscopic acellular mucin presenting on serosal surface and not being confined to mucosa; and (c) neoplastic epithelium dissecting outward beyond mucosa, however, with similar frequency of neoplastic cells being present in muscularis propria. (2) Involvement of neoplastic cells or/and acellular mucin at surgical margin did not necessarily lead to tumor recurrence or subsequent PMP, and clear margin did not absolutely prevent PMP development. (3) Coexisting diverticulum, resulted from neoplastic or non-neoplastic mucosa being herniated through muscle-lacking vascular hiatus of appendiceal wall, was seen in a quarter of LAMN cases, regardless of PMP. The diverticular portion of tumor involvement was often the weakest point where rupture occurred. In conclusion, proper evaluation of surgical specimens with search for mucin and neoplastic cells on serosa and for microscopic perforation, which are of prognostic significance, should be emphasized.
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Adenocarcinoma Mucinoso/patología , Adenocarcinoma Mucinoso/cirugía , Apendicectomía/métodos , Neoplasias del Apéndice/patología , Seudomixoma Peritoneal/patología , Adenocarcinoma Mucinoso/complicaciones , Adenocarcinoma Mucinoso/ultraestructura , Adolescente , Adulto , Anciano , Anciano de 80 o más Años , Estudios de Casos y Controles , Divertículo/etiología , Divertículo/patología , Femenino , Humanos , Masculino , Persona de Mediana Edad , Mucinas/ultraestructura , Clasificación del Tumor/métodos , Recurrencia Local de Neoplasia/prevención & control , Patología Quirúrgica/métodos , Pronóstico , Seudomixoma Peritoneal/diagnóstico , Seudomixoma Peritoneal/etiología , Estudios Retrospectivos , Gestión de Riesgos , Membrana Serosa/patología , Membrana Serosa/ultraestructura , Adulto JovenRESUMEN
ãIn order to characterize the adhesion and deformation behavior between chitosan-modified liposomes and the mucin layer of the small intestine, mucin was coated on hydrophobic surface-modified carbon nanotube (CNT) probe of an atomic force microscope. The interaction between this mucin layer and the liposomes with or without chitosan modification in phosphoric acid buffer solution was determined by atomic force microscopy. The pH of the buffer solution was controlled at 2.8 and 7.0. The chitosan modification increased the attractive force between the liposomes and mucin layer during the separation process under both pH conditions. This result corresponded with that from a previous study about the liposome adhesion behavior on the surface of the small intestine of rats. By using the mucin-coated CNT probe, the long range and different types of attractive forces between the chitosan-modified liposomes and mucin layer was observed. Furthermore, the small-scaled deformation behavior change on the liposomal surfaces due to chitosan modification was also observed by the CNT probe. The detail deformation and adhesion behavior of the liposomes with or without chitosan modification was detected.
Asunto(s)
Quitosano/química , Sistemas de Liberación de Medicamentos , Liposomas/química , Sondas Moleculares , Mucinas/química , Nanotubos de Carbono/química , Adhesividad , Animales , Tampones (Química) , Concentración de Iones de Hidrógeno , Interacciones Hidrofóbicas e Hidrofílicas , Intestino Delgado/metabolismo , Liposomas/metabolismo , Liposomas/ultraestructura , Microscopía de Fuerza Atómica , Sondas Moleculares/ultraestructura , Mucinas/ultraestructura , Nanotubos de Carbono/ultraestructura , Ácidos Fosfóricos/química , Ratas , Soluciones/química , Propiedades de SuperficieRESUMEN
Mucins are the main components of the gastrointestinal mucus layer. Mucin glycosylation is critical to most intermolecular and intercellular interactions. However, due to the highly complex and heterogeneous mucin glycan structures, the encoded biological information remains largely encrypted. Here we have developed a methodology based on force spectroscopy to identify biologically accessible glycoepitopes in purified porcine gastric mucin (pPGM) and purified porcine jejunal mucin (pPJM). The binding specificity of lectins Ricinus communis agglutinin I (RCA), peanut (Arachis hypogaea) agglutinin (PNA), Maackia amurensis lectin II (MALII), and Ulex europaeus agglutinin I (UEA) was utilized in force spectroscopy measurements to quantify the affinity and spatial distribution of their cognate sugars at the molecular scale. Binding energy of 4, 1.6, and 26 aJ was determined on pPGM for RCA, PNA, and UEA. Binding was abolished by competition with free ligands, demonstrating the validity of the affinity data. The distributions of the nearest binding site separations estimated the number of binding sites in a 200-nm mucin segment to be 4 for RCA, PNA, and UEA, and 1.8 for MALII. Binding site separations were affected by partial defucosylation of pPGM. Furthermore, we showed that this new approach can resolve differences between gastric and jejunum mucins.
Asunto(s)
Mucinas Gástricas/metabolismo , Mucinas/metabolismo , Polisacáridos/metabolismo , Animales , Mucinas Gástricas/química , Mucinas Gástricas/ultraestructura , Mucosa Gástrica/metabolismo , Mucosa Intestinal/metabolismo , Lectinas/química , Lectinas/metabolismo , Lectinas/ultraestructura , Microscopía de Fuerza Atómica/métodos , Mucinas/química , Mucinas/ultraestructura , Polisacáridos/química , Polisacáridos/ultraestructura , Análisis Espectral/métodos , Porcinos , Distribución TisularRESUMEN
Mucus, with its burden of inspired particulates and pathogens, is cleared from mucosal surfaces of the airways by cilia beating within the periciliary layer (PCL). The PCL is held to be "watery" and free of mucus by thixotropic-like forces arising from beating cilia. With radii of gyration ~250 nm, however, polymeric mucins should reptate readily into the PCL, so we assessed the glycocalyx for barrier functions. The PCL stained negative for MUC5AC and MUC5B, but it was positive for keratan sulfate (KS), a glycosaminoglycan commonly associated with glycoconjugates. Shotgun proteomics showed KS-rich fractions from mucus containing abundant tethered mucins, MUC1, MUC4, and MUC16, but no proteoglycans. Immuno-histology by light and electron microscopy localized MUC1 to microvilli, MUC4 and MUC20 to cilia, and MUC16 to goblet cells. Electron and atomic force microscopy revealed molecular lengths of 190-1,500 nm for tethered mucins, and a finely textured glycocalyx matrix filling interciliary spaces. Adenoviral particles were excluded from glycocalyx of the microvilli, whereas the smaller adenoassociated virus penetrated, but were trapped within. Hence, tethered mucins organized as a space-filling glycocalyx function as a selective barrier for the PCL, broadening their role in innate lung defense and offering new molecular targets for conventional and gene therapies.
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Glicocálix/metabolismo , Mucinas/metabolismo , Moco/metabolismo , Mucosa Respiratoria/metabolismo , Adenoviridae/metabolismo , Adenoviridae/ultraestructura , Animales , Técnicas de Cultivo de Célula , Cilios/ultraestructura , Dependovirus/metabolismo , Dependovirus/ultraestructura , Células Epiteliales/metabolismo , Glicocálix/ultraestructura , Glicosaminoglicanos/metabolismo , Cobayas , Humanos , Sulfato de Queratano/metabolismo , Mucinas/ultraestructura , Mucosa Respiratoria/virologíaRESUMEN
Moist mucosal epithelial interfaces that are exposed to external environments are dominated by sugar epitopes, some of which (e.g., sialic acids) are involved in host defense. In this study, we determined the abundance and distribution of two sialic acids to assess differences in their availability to an exogenous probe in isolated mucins and mucous gels. We used atomic force microscopy to obtain force maps of human preocular mucous and purified ocular mucins by probing and locating the interactions between tip-tethered lectins Maackia amurensis and Sambucus nigra and their respective receptors, α-2,3 and α-2,6 N-acetylneuraminic (sialic) acids. The rupture force distributions were not affected by neighboring sugar-bearing molecules. Energy contours for both lectin-sugar bonds were fitted to a two-barrier model, suggesting a conformational change before dissociation. In contrast to data from purified mucin molecules, the preocular gels presented numerous large clusters (19,000 ± 4000 nm(2)) of α-2,6 sialic acids, but very few small clusters (2000 ± 500 nm(2)) of α-2,3 epitopes. This indicates that mucins, which are rich in α-2,3 sialic acids, are only partially exposed at the surface of the mucous gel. Microorganisms that recognize α-2,3 sialic acids will encounter only isolated ligands, and the adhesion of other microorganisms will be enhanced by large islands of neighboring α-2,6 sialic acids. We have unveiled an additional level of mucosal surface heterogeneity, specifically in the distribution of pro- and antiadhesive sialic acids that protect underlying epithelia from viruses and bacteria.
Asunto(s)
Mecanismos de Defensa , Geles/química , Mucinas/química , Mucinas/ultraestructura , Membrana Mucosa/química , Ácidos Siálicos/química , Mezclas Complejas/química , HumanosRESUMEN
The mechanisms by which mucus helps prevent viruses from infecting mucosal surfaces are not well understood. We engineered non-mucoadhesive nanoparticles of various sizes and used them as probes to determine the spacing between mucin fibers (pore sizes) in fresh undiluted human cervicovaginal mucus (CVM) obtained from volunteers with healthy vaginal microflora. We found that most pores in CVM have diameters significantly larger than human viruses (average pore size 340 +/- 70 nm; range approximately 50-1800 nm). This mesh structure is substantially more open than the 15-100-nm spacing expected assuming mucus consists primarily of a random array of individual mucin fibers. Addition of a nonionic detergent to CVM caused the average pore size to decrease to 130 +/- 50 nm. This suggests hydrophobic interactions between lipid-coated "naked" protein regions on mucins normally cause mucin fibers to self-condense and/or bundle with other fibers, creating mucin "cables" at least three times thicker than individual mucin fibers. Although the native mesh structure is not tight enough to trap most viruses, we found that herpes simplex virus (approximately 180 nm) was strongly trapped in CVM, moving at least 8,000-fold slower than non-mucoadhesive 200-nm nanoparticles. This work provides an accurate measurement of the pore structure of fresh, hydrated ex vivo CVM and demonstrates that mucoadhesion, rather than steric obstruction, may be a critical protective mechanism against a major sexually transmitted virus and perhaps other viruses.
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Moco del Cuello Uterino/virología , Cuello del Útero/ultraestructura , Moco/virología , Simplexvirus/fisiología , Vagina/ultraestructura , Transporte Biológico , Adhesión Celular , Moco del Cuello Uterino/fisiología , Cuello del Útero/fisiología , Elasticidad , Femenino , Geles , Humanos , Mucinas/ultraestructura , Nanopartículas , Ovulación , Polietilenglicoles , Simplexvirus/ultraestructura , Vagina/fisiología , ViscosidadAsunto(s)
Córnea/cirugía , Endotelio Corneal/efectos de los fármacos , Soluciones Oftálmicas/administración & dosificación , Facoemulsificación/métodos , Irrigación Terapéutica , Córnea/ultraestructura , Endotelio Corneal/metabolismo , Endotelio Corneal/ultraestructura , Humanos , Mucinas/metabolismo , Mucinas/ultraestructura , Soluciones Oftálmicas/farmacologíaRESUMEN
In recent years, the exposure of biological systems to various nanomaterials has become an issue of great public concern. Although living organisms have arrays of biological defense mechanisms against exposure to exogenous compounds, the biochemical mechanisms allowing various nanomaterials to enter the body are not well understood. A unique example of a typical mucosal glycoprotein capable of binding and solubilizing nanomaterials in physiological solution is provided, suggesting a possible route for entry into biological systems.
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Mucinas/metabolismo , Nanoestructuras/química , Animales , Tampones (Química) , Bovinos , Cromatografía en Gel , Fulerenos/metabolismo , Ligandos , Luz , Microscopía de Fuerza Atómica , Microscopía de Túnel de Rastreo , Mucinas/ultraestructura , Nanoestructuras/ultraestructura , Nanotubos de Carbono/química , Dispersión de Radiación , Soluciones , Glándula Submandibular/químicaRESUMEN
PURPOSE: To evaluate human corneal endothelial mucin layer thickness and ultrastructure after phacoemulsification and irrigation-aspiration with either next generation ophthalmic irrigating solution (NGOIS) or BSS PLUS. METHODS: Paired human corneas were mounted in an artificial anterior chamber, exposed to 3 minutes of continuous ultrasound (US) at 80% power using the Alcon SERIES 20000 LEGACY surgical system (n = 9) or to 2 minutes of pulsed US at 50% power, 50% of the time at 20 pps using the Alcon INFINITI Vision System (n = 5), and irrigated with 250 mL of either NGOIS or BSS PLUS. A control group of paired corneas did not undergo phacoemulsification or irrigation-aspiration (n = 5). Corneas were divided and fixed for mucin staining or transmission electron microscopy. Mucin layer thickness was measured on the transmission electron microscopy prints. RESULTS: The mucin layer thickness in the continuous phaco group was 0.77 +/- 0.02 microm (mean +/- SE) with NGOIS and 0.51 +/- 0.01 microm with BSS PLUS (t test, P < 0.001). The mucin layer thickness in the pulsed phaco group was 0.79 +/- 0.02 microm with NGOIS and 0.54 +/- 0.01 microm with BSS PLUS (P < 0.001). The mucin layer thickness in the untreated control group was 0.72 +/- 0.02 microm. The endothelial ultrastructure was normal in all corneas. CONCLUSIONS: In this in vitro corneal model, NGOIS, due to its lower surface tension and higher viscosity, preserved endothelial mucin layer thickness better than BSS PLUS with both the INFINITI Vision System (pulsed US) and the LEGACY surgical system (continuous US).
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Córnea/cirugía , Endotelio Corneal/metabolismo , Mucinas/metabolismo , Soluciones Oftálmicas/administración & dosificación , Facoemulsificación/métodos , Irrigación Terapéutica , Anciano , Córnea/ultraestructura , Endotelio Corneal/efectos de los fármacos , Endotelio Corneal/ultraestructura , Humanos , Técnicas In Vitro , Persona de Mediana Edad , Mucinas/ultraestructura , Soluciones Oftálmicas/farmacologíaRESUMEN
A novel thermo- and pH-sensitive nanogel particle, which is a core-shell structured particle with a poly(N-isopropylacrylamide) (p(NIPAAm)) hydrogel core and a poly(ethylene glycol) monomethacrylate grafted poly(methacrylic acid) (p(MMA-g-EG)) shell, is of interest as a vehicle for the controlled release of peptide drugs. The interactions between such nanogel particles and artificial mucin layers during both approach and separation were successfully measured by using colloid probe atomic force microscopy (AFM) under various compression forces, scan velocities, and pH values. While the magnitudes of the compression forces and scan velocities did not affect the interactions during the approach process, the adhesive force during the separation process increased with these parameters. The pH values significantly influenced the interactions between the nanogel particles and a mucin layer. A large steric repulsive force and a long-range adhesive force were measured at neutral pH due to the swollen p(MMA-g-EG) shell. On the other hand, at low pH values, the steric repulsive force disappeared and a short-range adhesive force was detected, which resulted from the collapse of the shell layer. The nanogel particles possessed a pH response that was sufficient to protect the incorporated peptide drug under the harsh acidic conditions in the stomach and to effectively adhere to the mucin layer of the small intestine, where the pH is neutral. The relationships among the nanogel particle-mucin layer interactions, pH conditions, scan velocities, and compression forces were systemically investigated and discussed.
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Mucinas/química , Mucinas/ultraestructura , Acrilamidas/química , Adsorción , Coloides/química , Sistemas de Liberación de Medicamentos , Concentración de Iones de Hidrógeno , Microscopía de Fuerza Atómica , Microscopía Electrónica de Rastreo , Nanogeles , Tamaño de la Partícula , Polietilenglicoles/química , Polietileneimina/química , Ácidos Polimetacrílicos/química , Propiedades de SuperficieRESUMEN
Carmine has been used in biological staining to demonstrate selectively nuclei, chromosomes or mucins, depending on the formulation. Throughout its history in science, complaints and frustrations have been expressed about dye quality. Inconsistencies in dye quality or identity have prevented thorough understanding of staining mechanisms and have caused many stain solutions to behave unsatisfactorily. The aim of this review is to (1) detail causes of these problems, which are rooted in history, geography and production, (2) offer ways to minimize problems and (3) provide modern explanations for stain behavior. Carmine is a "semi-synthetic" dye, i.e., a complex of aluminum and the natural dye cochineal (carminic acid). Carmine shows considerable batch-to-batch variability. Geography, politics, history, agricultural practices and iconography all contribute to the variability of cochineal. In addition, widely divergent manufacturing methods are used to produce carmine. Also, confusion in terminology has led to mislabeling. Pressure from the food industry for a more satisfactory colorant for acidic foods led to the introduction of a new dye, aminocarminic acid, which could enter the biological market inadvertantly. Improved methods of analysis should help the certification process by the Biological Stain Commission. Further standardization could be achieved by replacing most of the methods of solubilizing carmine. The majority of these methods use heat, which is likely to damage the dye molecule. Fortunately, carmine is readily dissolved by raising the pH of the aqueous solvent above 12, and a new form of the dye, now available commercially, is soluble in water without the need for heat or pH adjustment. Chemical structures and physical properties of carminic acid, carmine, aminocarminic acid and kermesic acid are reviewed. A new configuration for carmine is proposed, as well as possible changes to carminic acid and carmine molecules as a result of decomposition caused by heating. Each of the major classes of carmine-based stains is described as are possible mechanisms of attachment to specific substrates. Glycogen binds carmine through hydrogen bonding, and it is here that carmine decomposed by heat could have the greatest detrimental impact. Nuclei and chromosomes are stained via coordination bonds, perhaps supplemented by hydrogen bonds. Finally, acidic mucins react ionically with carmine. Specificity in the latter case may be due to unique polymeric carmine molecules that form in the presence of aluminum chloride.
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Carmín/química , Núcleo Celular/ultraestructura , Cromosomas/ultraestructura , Mucinas/ultraestructura , Coloración y Etiquetado/métodosRESUMEN
CA125 antigen is a high molecular mass, structurally heterogeneous, mucin-type molecule expressed during embryonic development as well as in adult human tissues. This study was aimed at investigating its mucin-related property of ferning, as a general complementary way of characterization. Pregnancy-associated CA125 antigen (pCA125) was examined using light, transmission and scanning electron microscopy and compared with cancer-derived CA125 antigen (cCA125). The results obtained for spread-out, air-dried pCA125 and cCA125 samples revealed clear differences in the patterns of crystalline as well as amorphous material. Thus, the fern-like crystals were mainly sparsely distributed and their morphology was atypical. The extent of crystallization of pCA125 was moderately lower than that of cCA125 antigen, whereas variation in the size and spatial organization of fern crystals was evident. Besides the material with a crystalline appearance, differences in the organic substrate were also noticeable. In contrast to the sponge-like appearance of pCA125, cCA125 had a more compact structure. These initial data may be relevant for relating biochemical properties of CA125 antigen with its morphology as a basis for elucidating its still obscure function under different physiological conditions.
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Antígeno Ca-125/ultraestructura , Mucinas/ultraestructura , Antígeno Ca-125/química , Cristalización , Femenino , Humanos , Microscopía Electrónica de Rastreo , Microscopía Electrónica de Transmisión , Mucinas/química , EmbarazoRESUMEN
Atomic force microscopy (AFM) has been used to show that human ocular mucins contain at least three distinct polymer conformations, separable by isopycnic density gradient centrifugation. In this work we have used affinity purification against the anti(mucin peptide core) monoclonal antibody 45M1 to isolate MUC5AC gene products, a major component of human ocular mucins. AFM images confirm that the affinity-purified polymers adopt distinct conformations that coidentify with two of those observed in the parent population, and further reveal that these two different conformations can be present within the same polymer. AFM images of the complexes formed after incubation of 45M1 with the parent sample reveal different rates of binding to the two MUC5AC polymer types. The variability of gene products within a mucin population was revealed by analyzing the height distributions along the polymer contour and periodicities in distances between occupied antibody binding sites. AFM analysis of mucin polymers at the single molecule level provides new information about the genetic origins of individual polymers and the contributions of glycosylation to the physicochemical properties of mucins, which can be correlated with information obtained from biochemistry, antibody binding assays, and molecular biology techniques.
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Ojo/química , Mucinas/química , Mucinas/aislamiento & purificación , Conformación Proteica , Anticuerpos Monoclonales/metabolismo , Conjuntiva/química , Humanos , Mucina 5AC , Mucinas/genética , Mucinas/ultraestructura , Polímeros/química , Polímeros/metabolismoRESUMEN
In this paper the surface activity of protein mucin at solution/air interface has been studied. The experiments of the adsorbed protein at solution/air interface have been carried out with a range of protein concentrations at a defined pH. The adsorption of the protein to solid surfaces and the degree of hydrophobicity at solid/solution interface of mucin have been evaluated at different pH and in the presence of Hofmeister electrolyte. The results from these studies have been further substantiated by surface potential measurements of mucin covered surface on stainless steel. Quartz crystal microbalance (QCM) has been used to follow the protein adsorption kinetics from solution to solid surface. The results from these measurements show that the adsorption behavior has a remarkable dependence on the degree of maximum coverage and is almost independent of the ionic strength. Other characteristic features such as maximum adsorption values at the protein isoelectric point (IEP4.7) and low-affinity isotherms that showed surface saturation even under unfavorable electrostatic conditions have been observed. The amount of mucin adsorbed in the presence of electrolytes has been estimated using electron spectroscopy for chemical analysis (ESCA). The study clearly shows that there exists an inverse relationship between the hydrophobicity and surface tension of the protein and also on the hydrated radius of Hofmeister electrolyte used.
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Aire , Mucinas/química , Soluciones/química , Concentración de Iones de Hidrógeno , Microscopía de Fuerza Atómica , Mucinas/ultraestructura , Agua/químicaRESUMEN
Se emplearon las técnicas histoquímicas convencionales para mucinas (PAS, Alcian blue y Azul de toluidina) y la técnica de avidina-biotina para estudiar la unión de las lectinas PNA, UEA-1, RCA-1, ConA, DBA, SBA y WGA a los azúcares específicos en cortes histológicos de glándulas inguales anteriores de Blandin y Nuhn. Las células secretoras mucosas y serosas exhibieron diferentes grados de coloración dependiendo de la lectina y el tipo celular. Estos resultados proveen las bases para la comparación de posibles cambios en las enfermedades de las glándulas salivales menores (AU)
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Humanos , Masculino , Femenino , Adulto , Persona de Mediana Edad , Glándulas Salivales Menores/anatomía & histología , Glándulas Salivales Menores/ultraestructura , Histocitoquímica/métodos , Mucinas/ultraestructura , Lectinas/química , Técnicas Histológicas , Ácido Aminosalicílico/diagnóstico , Neuraminidasa/diagnóstico , Glicoproteínas/química , Glicoproteínas/ultraestructura , Lengua/citología , Lengua/ultraestructura , CadáverRESUMEN
BACKGROUND: Tear secretion and tear film stability seem to be influenced by pseudoexfoliation syndrome (PEX). Histopathological evaluation of conjunctival goblet cells in PEX patients might explain the influence on tear film stability. METHODS: In a prospective, cross-sectional study, 40 eyes of 40 patients with PEX (study group) had measurement of Schirmer test with anesthesia and break-up time prior to cataract surgery. At the end of an uneventful operation, a 1 x 1.5 mm sample of conjunctival tissue was obtained and light and electron microscopy were performed. Results were compared with a control group. Histology evaluation was masked. Primary outcome measures included Schirmer test with anesthesia, break-up time, goblet cell density and morphological character of conjunctiva and conjunctival goblet cells. RESULTS: Both Schirmer test and break-up time values were significantly lower (P= 0.01 and P= 0.001) in the PEX patients (mean 10.6 mm and 8.6 s respectively) than in the control group (13.4 mm and 12.3 s respectively). The number of goblet cells in patients with PEX compared with the control group showed no statistically significant difference (P= 0.66). Use of trichrome stain revealed significant differences in the staining properties of goblet cells between patients with PEX and controls. On electron microscopy, typical pseudoexfoliation filaments were found in the connective tissue of conjunctiva of PEX patients. Remarkable changes of mucin pockets in the study group were also noticed; they had extremely irregular distribution, various forms of size and appearance and even complete collapse. CONCLUSION: Pseudoexfoliation seems to alter basic features of goblet cell morphology, thus affecting tear film stability. Further studies are necessary to determine the exact mechanism.
Asunto(s)
Conjuntiva/ultraestructura , Síndrome de Exfoliación/patología , Células Caliciformes/ultraestructura , Lágrimas/metabolismo , Anciano , Anciano de 80 o más Años , Tejido Conectivo/ultraestructura , Estudios Transversales , Síndrome de Exfoliación/metabolismo , Femenino , Humanos , Masculino , Persona de Mediana Edad , Mucinas/ultraestructura , Estudios ProspectivosRESUMEN
PURPOSE: The structure of mucin balls collected from silicone hydrogel contact lens wearers was examined to determine their nature. METHODS: Tears containing mucin balls were collected using a capillary tube. These were processed for light microscopic histochemistry, scanning electron microscopy, and electron microscopic elemental analysis. Mucin balls were also observed in vivo using confocal microscopy. RESULTS: Histology showed that the mucin balls were PAS positive, indicating that glycoproteins form a major component. Lipids and bacteria were not detected. Scanning electron microscopy did not show the surface to be smooth but revealed a variation in density across the surface. Elemental analysis was inconclusive. CONCLUSIONS: Mucin balls are likely to be made from collapsed mucin and are unlikely to have been formed as a result of pearling around a silicon, lipid, or bacterial kernel.