Kinetic characteristics of the excitability-inducing material channel in oxidized cholesterol and brain lipid bilayer membranes.

The kinetic characteristics of the opening and closing of the excitability-inducing material (EIM) channel in oxidized cholesterol and in brain lipid bilayers are compared. The kinetics of the opening and closing of individual ion-conducting channels in bilayers doped with small amounts of EIM are determined from discrete fluctuations in ionic current. The kinetics for approach to steady-state conductance are determined for lipid bilayers containing many channels. Steady-state and kinetic characteristics for the EIM channel incorporated in brain lipid bilayers can be accounted for by the model developed for the EIM channel incorporated in oxidized cholesterol membranes. Relaxation time, calculated from rate constants of single-channel membranes or directly measured in many-channel membranes is strongly temperature dependent, and is always shorter in brain lipid membranes. Changes in temperature do not affect the interaction of the electric field and the open channel, but the open configuration of the EIM channel in brain lipid bilayers is stablized with increasing temperature. The configurational energy difference between the open and closed channel, calculated from temperature studies, is larger in brain lipid bilayers. The energy barrier which separates the two configurations of the channel is larger in oxidized cholesterol bilayers.

Tendinopatía cálcica: etiopatogenia y evaluación por imágenes / Calcific tendinitis: aetiopathogenesis and imaging evaluation

Resumen: La tendinopatía cálcica es causada por el depósito patológico de cristales de hidroxiapatita de calcio en los tendones y es una causa común de dolor en las articulaciones. Afecta más frecuentemente al hombro y la cadera, con hallazgos característicos en imágenes; sin embargo, cualquier tendón puede estar involucrado. Ocasionalmente, la tendinopatía cálcica puede simular patología agresiva, como infección o neoplasia, especialmente en RM. Fisiotpatológicamente, las calcificaciones provendrían de una diferenciación anormal de las células madre del tendón, que comienzan a producir calcio, aunque todavía no es del todo claro. Los radiólogos deben estar familiarizados con los hallazgos de las imágenes para distinguir la tendinopatía cálcica de procesos más agresivos. La aspiración y lavado guiado bajo ecografía es una técnica útil realizada por el radiólogo para el tratamiento de casos sintomáticos. La familiaridad con estos procedimientos y su apariencia en imágenes es un aspecto importante en el manejo de esta enfermedad. El propósito de esta revisión es analizar la etiopatogenia de la tendinopatía cálcica, la evaluación con imágenes en los sitios de presentación más comunes y también en los menos frecuentes, así como el papel que desempeña la ecografía en el tratamiento de la patología.

Abstract: Calcific tendinitis is caused by abnormal deposition of calcium hydroxyapatite crystals in tendons and is a common cause of joint pain. The disease typically affects the shoulder and hip, with characteristic imaging findings; however, any tendon can be involved. Occasionally, calcific tendinitis can mimic aggressive disorders, such as infection and neoplasm, especially on MRI. Apparently, the calcifications come from an abnormal differentiation of the tendon stem cells, which begin to produce calcium. Radiologists should be familiar with the imaging findings to distinguish calcific tendinitis from more aggressive processes. Image-guided percutaneous needle aspiration is a useful technique performed by the radiologist for the treatment of symptomatic cases. Being familiar with these processes and their imaging appearance is an important aspect in the management of this common disease. The purpose of this review is to analyze the pathogenesis of calcium tendinopathy, the evaluation of images in both the most common and less frequent presentation sites, as well as the role played by ultrasound in the treatment of pathology.

Hormonal control of oviductal ciliary activity: effect of prostaglandins.

Prostaglandins have been shown to exist in the walls of the oviduct and to effect strongly oviductal muscle contractions and egg transport. Our observations, using laser light-scattering spectroscopy, indicate that the "natural" prostaglandins F2 alpha, E1, and E2 can stimulate ciliary activity in cultures of ciliated epithelium of the rabbit oviduct. These findings suggest a new alternative to explain the effect of prostaglandins on oviductal egg transport.

The oviductal cilia and Kartagener's syndrome.

Women who have Kartagener's syndrome (primary ciliary dyskinesia) may or may not be fertile. The bronchial mucociliary clearance is reduced markedly in most of these women; this has led investigators to the conclusion that the cilia in the respiratory tract are immotile, and that "beating cilia may have no indispensable role in the female reproductive tract." Yet motile cilia are considered by many workers to be essential for normal ovum transport. More recently, bizarre ciliary motion has been described in the respiratory cilia of Kartagener's women. Our hypothesis was that the dyskinetic ciliary activity (or immotility) would be the same in both the respiratory and reproductive tracts and thus explain the fertility (or lack of it) in Kartagener's women. This report shows an identical ultrastructure and absolute immotility of cilia in both the respiratory tract and reproductive tract of a woman with Kartagener's syndrome who has never conceived. From this concordance, we suggest that the fertility of Kartagener's women is explained by the dyskinetic motion of oviductal cilia, and that the ciliated endosalpinx is essential for human reproduction.

Molecular mechanism of mucin secretion: I. The role of intragranular charge shielding.

Mucus is an ubiquitous polymer hydrogel that functions as a protective coat on the surface of integument and mucosa of species ranging from simple animals (such as coelenterates) to mammals. The polymer matrix of mucus is made out of long-chain glycoproteins called mucins that are tangled together, forming a randomly woven, highly polyionic network (Lee et al., 1977; Verdugo et al., 1983). Mucin-containing granules, produced by mammalian goblet cells in vitro, undergo massive post-exocytotic swelling. Their swelling kinetics is similar to the swelling of condensed artificial polymer gels (Verdugo, 1984; Tanaka and Fillmore, 1979). We had proposed that mucins must be condensed in the secretory granule and expand by hydration during or after exocytosis (Verdugo, 1984; Tam and Verdugo, 1981). However, the polyionic charges of mucins prevents condensation unless they (the mucins) are appropriately shielded. The present experiments were designed to assert the presence of an intragranular shielding cation and its role in secretion. Giant mucin granules of the slug (Ariolimax columbianus) are released intact from mucus-secreting cells of the slug's skin. They burst spontaneously outside the cell, forming, upon hydration, the typical slug mucus (Deyrup-Olsen et al., 1983). We report here that these granules contain from 2.5 to 3.6 moles calcium/kg dry material, and that calcium is released from the granules immediately before the burst that discharges their secretory product. Therefore, we propose that calcium functions as a shielding cation of polyionic mucins, and that the bursting discharge of mucins from secretory granules must result from the release of calcium from the intragranular compartment.(ABSTRACT TRUNCATED AT 250 WORDS)

Conformational structure of respiratory mucus studied by laser correlation spectroscopy.

Samples of respiratory mucus were obtained from the trachea of dogs and patients undergoing bronchoscopy. The samples were studied by laser correlation spectroscopy. The autocorrelation function of laser light scattered by both human and canine respiratory mucus was a single exponential in thick mucus or a double exponential in thin watery mucus. This finding suggests that, as in the case of uterine cervical mucus, the molecular structure of respiratory mucus is an ensemble of entangled, randomly-coiled glycoproteins forming a loose network of variable density rather than a covalently cross-linked molecular network as proposed in earlier studies.

Molecular mechanism of product storage and release in mucin secretion. II. The role of extracellular Ca++.

Mucin-containing granules, produced by mammalian goblet cells in vitro, undergo massive post-exocytotic swelling (23). Their swelling kinetics are similar to the swelling of condensed artificial polymer gels (22). Earlier, we proposed that mucins are condensed in the secretory granule and expand by swelling during or after exocytosis (21). The swelling of mucus is affected by ionic influences, as it is governed by a Donnan equilibrium process (21). However, the effect of cations on the swelling of newly released mucins had not yet been investigated. Calcium has been found in high concentration inside secretory granules of mucin-secreting cells (18, 9, 25), and is also elevated in the mucus of cystic fibrosis patients (17). The present experiments were designed to study the effect of extracellular Ca++ concentration on the swelling kinetics of the newly released secretory product of respiratory goblet cells in vitro. The data show that extracellular Ca++, in concentrations similar to those found in the mucus of cystic fibrosis patients (2 to 4 mM) can produce a four-fold decrease in the diffusivity of the newly released mucin polymer network, resulting in a slow rate of swelling, and a mucus that remains thick for long periods of time. The present findings are in agreement with the Donnan equilibrium hypothesis for the regulation of mucus swelling and rheology (21), and bear important implications for the pathophysiology of cystic fibrosis.

Development of an in vitro model of primate cervical goblet cells.

Mucins, are densely packed in secretory granules of goblet cells. Upon exocytosis they undergo massive hydration that results in the formation of the mucus gel. Because the mucin polymer network is held together by tangles and low energy bonds, the rheological properties of this gel are mainly determined by the degree of postexocytotic hydration. Hydration in mucus is governed by a Donnan equilibrium as it is driven by electrostatic interaction among the polyionic charges of the mucins and other fixed polyions. Although, variations of charge density of the mucin polymer could be an efficient physiologic mechanism to control the rate of mucus hydration and rheology, this subject has not been investigated. In here we describe a primary tissue culture system of cervical goblet cells of the monkey uterus. This preparation allows to measure directly the kinetic of hydration of exocytosed mucins. Because the physicochemical parameters of the bathing medium can be effectively controlled, variations in the kinetic of mucins swelling upon exocytosis, can be used as a convenient indicator of fluctuations of charge density in secretory products. Since the cervical mucosa readily respond to endocrine influences, this preparation can provide a useful model to study the effect of hormones or other transmitters on polyionic charge density of secretory product.

Procedimientos intervencionales guiados por ultrasonido en radiología musculoesquelética / Ultrasound guided interventional procedures in musculoskeletal radiology

Ultrasound is a useful diagnostic modality to study many structures such as subcutaneous tissue, tendons, muscles, joints, and nerves. It has low cost, wide availability and high resolution. These advantages make ultrasound a good modality in interventional procedures like soft tissue tumors biopsy, aspiration of cysts and other collections, and also in treating symptomatic calcifications like deposition of hidroxiapatite crystals in the rotator cuff, among other indications. Our objetive is to present the experience of the authors in performing musculoskeletal interventional procedures by ultrasound.

El ultrasonido es una modalidad imaginológica útil para el estudio de múltiples estructuras, tales como tejidos subcutáneos, tendones, músculos, articulaciones y nervios. Tiene un bajo costo, amplia disponibilidad y alta resolución. Estas ventajas hacen del ultrasonido una excelente modalidad en procedimientos intervencionales tales como biopsias de tejidos de partes blandas, aspiración de quistes y otras colecciones y también en el tratamiento de calcificaciones sintomáticas, tales como depósitos de cristales de hidroxiapatita de calcio en el manguito rotador. Este artículo desea mostrar la experiencia de los autores en la realización de procedimientos intervencionales musculoesqueléticos guiados por ultrasonido.

Mucin exocytosis.

Mucins produced by goblet cells of the respiratory mucosa are condensed while stored in secretory granules. Mucin condensation and its decondensation upon exocytosis can be explained by the theory of polymer gel phase transition. After the opening of a secretory pore, Ca2+ inside the granule is exchanged for extracellular Na+. Na/Ca exchange triggers a polymer gel phase transition whereby the mucin polymer matrix undergoes massive swelling and thereby changes from a condensed to a hydrated phase. Swelling of the granular content is driven by a Donnan potential and results in the release of secretory product and the formation of small mucin gels, which later anneal to each other to form the respiratory mucus. Because of the tangled rather than cross-linked topology of the mucin network, the rheologic properties of the respiratory mucus depend primarily on hydration. As mucins are polyionic, the hydration of mucus is controlled by a Donnan equilibrium. Hence, mucus hydration and rheology are determined by two factors: the quantity, chain length, and charge density of the secreted mucins, and the amount and the ionic and polyionic composition of the water transported across the respiratory mucosa.

Ca2+-dependent hormonal stimulation of ciliary activity.

It has been demonstrated that calcium modulates ciliary activity in protozoa and also in epithelial cilia of the mussel gill. Changes in the frequency of ciliary beat in the oviduct of the salamander have also been associated with movement of Ca2 across the cell membrane. However, the control of ciliary activity in mammals is poorly understood and the function of calcium in mammalian cilia and its role in coupling hormonal effects to changes in ciliary activity have been only preliminarily investigated. The evidence presented here suggests that the stimulus-response coupling of the stimulating effect of prostaglandin E2 (PGE2) on ciliary activity of the rabbit oviduct is carried out by release of intracellular Ca2+.

Hydration kinetics of exocytosed mucins in cultured secretory cells of the rabbit trachea: a new model.

Experiments have been done to test the idea that mucins undergo postexocytotic swelling. Previous work led to the hypothesis that the glycoprotein network of the mucus gel is probably held together by entanglements and low energy bonds, rather than by interchain covalent bonding. Since glycoproteins and other proteins in the mucus are polyions, it was further proposed that mucus must be capable of swelling, with its swelling properties depending on the pH and ionic strength of the medium hydrating the mucus. Experiments using oestrous cervical mucus from cows as a model confirmed this prediction. Observations on tissue cultures of respiratory secretory cells reported here show that freshly secreted mucins also undergo swelling during and after exocytosis. This evidence supports the hypothesis that the rheological properties of mucus may be physiologically regulated by hydration via control of the transepithelial movement of water, ions and soluble proteins, rather than by variations in the degree of covalent cross-linking between glycoprotein chains as proposed earlier.

Laser light-scattering spectroscopy: a new application in the study of ciliary activity.

A uniquely precise and simple method to study ciliary activity by laser light-scattering spectroscopy has been developed and validated. A concurrent study of the effect of Ca2+ on ciliary activity in vitro by laser scattering spectroscopy and high speed cinematography has demonstrated that this new method is simpler and as accurate and reproducible as the high speed film technique.

Donnan mechanism of mucin release and conditioning in goblet cells: the role of polyions.

Mucin, the principal polymeric species in the mucus matrix, is condensed inside secretory granules and undergoes massive swelling upon exocytosis. Mucin swelling is governed by a Donnan equilibrium. However, the effect of polyions such as soluble proteins on the swelling of mucin granules has not been investigated. The experiments reported here were designed to evaluate the effect of albumin on swelling kinetics of mucin granules exocytosed from respiratory goblet cells in culture. The kinetics of swelling was monitored by video-microscopy. The diffusivity of newly released mucins, in the presence of different concentrations of serum albumin, was evaluated using the expression: D = r2f/tau where tau is the characteristic time of the swelling, and rf is the final equilibrium radius of the swollen granule. Preliminary results indicate that serum albumin at concentrations of 10(-7) M, which are equivalent to those found in the bronchial mucus of asthmatic or cystic fibrosis patients, can produce up to a 90% decrease in the diffusivity of newly released mucins. Albumin is commonly present on the surface of the respiratory mucosa, and its concentration is increased in asthma and other bronchial inflammatory diseases. The evidence presented here shows that soluble proteins can strongly modulate the rate of swelling of newly released mucins, as predicted by Donnan equilibrium. Since swelling is a critical determinant of mucus rheology, the concentration of plasma proteins on the mucosa could play an important role in the regulation of the rheological properties of mucus. Also, the characteristically thick mucus found in chronic bronchial inflammatory diseases could be at least partially explained by the high levels of albumin found in the airways of these patients.

Enrichment of subpopulations of respiratory epithelial cells using flow cytometry.

The application of flow cytometry to enrich airway epithelial cell subpopulations is described. A complementary epithelial cell preparative technique is also outlined. The ability of the airway epithelium to protect the lung from environmental insults results from a complex interaction among the different cells that form its matrix. The separation of the different epithelial cell types is an essential step in the studies of mechanisms of the controlling factors of cell repair, cell differentiation, and neoplastic transformation. Epithelial cells of the New Zealand white rabbit trachea are prepared using enzymatic digestion and microdissection. Small sections of tracheal wall are dissected into pieces approximately 10 mm2. The mucosa is dissected and placed in 0.15% hyaluronidase for 40 min at 22 degrees C. Mucus is removed, and the mucosa is then placed in 0.1% pronase at 37 degrees C for 30 min. With careful dissection, the epithelium can be dissected from the mucosa in 10-mm2 sheets. Sheets of epithelial cells are placed in 6 ml of an enzymatic solution containing collagenase, 0.2% bovine serum albumin, 0.04% soya bean trypsin inhibitor, 0.06 ml of 1 M Hepes buffer for 3 h at 37 degrees C. The cells are gently pipetted during the 3-h period, yielding a suspension of viable cells. Subpopulations of these different cell types are enriched using an Orthocytofluorograph 50111. A krypton ion laser was used for excitation of cells at 488 nm. Forward-angle and 90 degrees scatter were gated on the histogram. The purification of the ciliated, basal, and secretory cells was 90%, 97%, and 94%, respectively.(ABSTRACT TRUNCATED AT 250 WORDS)

Reversible condensation of mast cell secretory products in vitro.

We have investigated the mechanisms responsible for the condensation and decondensation of secretory products that occur in mast cell secretion. We show here that the hydrated matrix of an exocytosed secretory granule can be recondensed to its original volume by exposure to acidic solutions containing histamine at concentrations that mimic those found in vivo. Recondensation by acidic histamine began in the range of 1-10 mM with a dose response curve that was accurately predicted by a Hill type equation with four highly cooperative binding sites and a half maximum concentration of [Hi++] = 3.9 mM. Recondensation by histamine showed a sigmoidal dependency on pH (critical range pH 5.5-6.5) and was fully reversible. These experiments suggest that histamine, possibly by binding to anionic sites in the protein-heparin complex of the granule matrix, triggers a change in the polymeric structures of the granule matrix from an extended coil to a collapsed globular state. This may be a useful model for understanding the condensation of secretory products into dense core granules and their subsequent decondensation upon exocytosis.

beta-Adrenergic stimulation of respiratory ciliary activity.

We investigated the effect of isoproterenol on ciliary activity using a mucus-free preparation of cultured ciliated cells of the rabbit trachea. The frequency of ciliary beating was monitored by dynamic laser-scattering spectroscopy. The results demonstrated that isoproterenol directly stimulates the activity of ciliated cells of the respiratory epithelium and that this effect is beta-adrenergic specific inasmuch as the observed stimulation can be blocked by propranolol.