Similarities and differences in the autonomic control of airway and urinary bladder smooth muscle

The airways and the urinary bladder are both hollow organs serving very different functions, i.e. air flow and urine storage, respectively. While the autonomic nervous system seems to play only a minor if any role in the physiological regulation of airway tone during normal breathing, it is important in the physiological regulation of bladder smooth muscle contraction and relaxation. While both tissues share a greater expression of M2 than of M3 muscarinic receptors, smooth muscle contraction in both is largely mediated by the smaller M3 population apparently involving phospholipase C activation to only a minor if any extent. While smooth muscle in both tissues can be relaxed by β-adrenoceptor stimulation, this primarily involves β2-adrenoceptors in human airways and β3-adrenoceptors in human bladder. Despite activation of adenylyl cyclase by either subtype, cyclic adenosine monophosphate plays only a minor role in bladder relaxation by β-agonists; an important but not exclusive function is known in airway relaxation. While airway β2-adrenoceptors are sensitive to agonist-induced desensitization, β3-adrenoceptors are generally considered to exhibit much less if any sensitivity to desensitization. Gene polymorphisms exist in the genes of both β2- and β3-adrenoceptors. Despite being not fully conclusive, the available data suggest some role of β2-adrenoceptor polymorphisms in airway function and its treatment by receptor agonists, whereas the available data on β3-adrenoceptor polymorphisms and bladder function are too limited to allow robust interpretation. We conclude that the distinct functions of airways and urinary bladder are reflected in a differential regulation by the autonomic nervous system. Studying these differences may be informative for a better understanding of each tissue

Signal transduction underlying the control of urinary bladder smooth muscle tone by muscarinic receptors and β-adrenoceptors

The normal physiological contraction of the urinary bladder, which is required for voiding, is predominantly mediated by muscarinic receptors, primarily the M3 subtype, with the M2 subtype providing a secondary backup role. Bladder relaxation, which is required for urine storage, is mediated by β-adrenoceptors, in most species involving a strong β3-component. An excessive stimulation of contraction or a reduced relaxation of the detrusor smooth muscle during the storage phase of the micturition cycle may contribute to bladder dysfunction known as the overactive bladder. Therefore, interference with the signal transduction of these receptors may be a viable approach to develop drugs for the treatment of overactive bladder. The prototypical signaling pathway of M3 receptors is activation of phospholipase C (PLC), and this pathway is also activated in the bladder. Nevertheless, PLC apparently contributes only in a very minor way to bladder contraction. Rather, muscarinic-receptor-mediated bladder contraction involves voltage-operated Ca2+ channels and Rho kinase. The prototypical signaling pathway of β-adrenoceptors is an activation of adenylyl cyclase with the subsequent formation of cAMP. Nevertheless, cAMP apparently contributes in a minor way only to β-adrenoceptor-mediated bladder relaxation. BKCa channels may play a greater role in β-adrenoceptor-mediated bladder relaxation. We conclude that apart from muscarinic receptor antagonists and β-adrenoceptor agonists, inhibitors of Rho kinase and activators of BKCa channels may have potential to treat an overactive bladder

Adaptive control of cooperating sensors - focus and stereo ranging with an agile camera system

This paper presents a cooperative computer vision procedure in which focus ranging and stereo ranging operate together, verifying the results of each in computing the position (but not the shape) of arbitrary objects in a stationary, unknown environment. The procedure increases the reliability of the position measurements by enforcing measurement consistency via mutual constraint, and increases their accuracy by combining them with a maximum likelihood estimator into an estimate of lower variance than any of the measurements alone. The final outcome of the procedure is a set of estimated three-dimensional points together with their estimated uncertainties built from a sequence of dynamic, adaptive sensing operations. The results of 75 experiments processing close to 3000 different obiect points lying between 1 and 3 meters distant from the cameras show that the integrated range values are (I) highly reliable, since no mistaken combined range measurements are observed, and (II) more pre cise than either of the computed ranges alone. The cooperative methodology extends to more and different sensors, and the results lend practical credence to the view that multiple sensors (I) allow the limitations of a single sensor to be circumvented, (II) provide larger, statistically more effective data sets, (III) reduce mistakes generated by inaccurate interpretation models, using sensors outside of their known operating regions, and sensor failure

An experimental investigation of estimation approaches for optical flow fields

Various approaches have been suggested to solve the correspondence problem for image sequences. This chapter discusses two basically different approaches for the estimation of optical flow vector fields in order to clarify their advantages and disadvantages as well as the relation between them. The first approach is based on the extraction and interframe match of features. Several features are investigated using real-world images. The performance of the approach involving features is evaluated. In distinction to feature-based approaches, one may directly evaluate the spatio-temporal variation of the picture function which results in a differential or gradient-based approach. This gradient-based approach has been supplemented by a smoothness requirements on the optical flow field, in which the estimation of the optical flow field formulated as an optimization problem resulting in a system of partial differential equations for the optical flow field. Subsequent investigations show that s ignificant contributions for the determination of the optical flow field could be expected among others from gray value structures which correspond to the image locations evaluated in the feature-based approach. Results from both approaches obtained using the same input data are compared

CHEMDAT - ein Programm zur Bearbeitung von chemischen Wasseranalysen

TIB: ZA 2122 (46) / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekSIGLEDEGerman

Incremental Natural Language Description of Dynamic Imagery

Although image understanding and natural language processing constitute two major areas of AI, they have mostly been studied independently of each other. Only a few attempts have been concerned with the integration of computer vision and the generation of natural language expressions for the description of image sequences. The aim of our joint efforts at combining a vision system and a natural language access system is the automatic simultaneous description of dynamic imagery, i.e., we are interested in image interpretation and language processing on an incremental basis. In this contribution 1 we sketch an approach towards the integration of the Karlsruhe vision system called Actions and the natural language component Vitra developed in Saarbrücken. The steps toward realization, base

The pharmacological rationale for combining muscarinic receptor antagonists and β-adrenoceptor agonists in the treatment of airway and bladder disease

Muscarinic receptor antagonists and beta-adrenoceptor agonists are used in the treatment of obstructive airway disease and overactive bladder syndrome. Here we review the pharmacological rationale for their combination. Muscarinic receptors and beta-adrenoceptors are physiological antagonists for smooth muscle tone in airways and bladder. Muscarinic agonism may attenuate beta-adrenoceptor-mediated relaxation more than other contractile stimuli. Chronic treatment with one drug class may regulate expression of the target receptor but also that of the opposing receptor. Prejunctional beta(2)-adrenoceptors can enhance neuronal acetylcholine release. Moreover, at least in the airways, muscarinic receptors and beta-adrenoceptors are expressed in different locations, indicating that only a combined modulation of both systems may cause dilatation along the entire bronchial tree. While all of these factors contribute to a rationale for a combination of muscarinic receptor antagonists and beta-adrenoceptor agonists, the full value of such combination as compared to monotherapy can only be determined in clinical studies