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Tear Secretion (tear + secretion)
Selected AbstractsRole of aquaporins in endothelial water transportJOURNAL OF ANATOMY, Issue 5 2002A. S. Verkman The aquaporins (AQP) are a family of homologous water channels expressed in many epithelial and endothelial cell types involved in fluid transport. AQP1 protein is strongly expressed in most microvascular endothelia outside of the brain as well as in endothelial cells in cornea, intestinal lacteals, and other tissues. AQP4 is expressed in astroglial foot processes adjacent to endothelial cells in the central nervous system. Transgenic mice lacking aquaporins have been useful in defining their role in mammalian physiology. Mice lacking AQP1 manifest defective urinary concentrating ability, in part because of decreased water permeability in renal vasa recta microvessels. These mice also show a defect in dietary fat processing that may involve chylomicron absorption by intestinal lacteals. There is preliminary evidence that AQP1 might play a role in tumour angiogenesis and in renal microvessel structural adaptation. However AQP1 in most endothelial tissues does not appear to have a physiological function despite its role in osmotically driven water transport. For example mice lacking AQP1 have low alveolar capillary water permeability but unimpaired lung fluid absorption, as well as unimpaired saliva and tear secretion, aqueous fluid outflow, and pleural and peritoneal fluid transport. In the central nervous system mice lacking AQP4 are partially protected from brain oedema in water intoxication and ischaemic models of brain injury. Therefore although the role of aquaporins in epithelial fluid transport is in most cases well understood there remain many questions about the role of aquaporins in endothelial cell function. It is unclear why many leaky microvessels strongly express AQP1 without apparent functional significance. Improved understanding of aquaporin endothelial biology may lead to novel therapies for human disease, such as pharmacological modulation of tumour angiogenesis, renal fluid clearance and intestinal absorption. [source] Effect of P2X7 receptor knockout on exocrine secretion of pancreas, salivary glands and lacrimal glandsTHE JOURNAL OF PHYSIOLOGY, Issue 18 2010Ivana Novak The purinergic P2X7 receptors are expressed in different cell types where they have varied functions, including regulation of cell survival. The P2X7 receptors are also expressed in exocrine glands, but their integrated role in secretion is unclear. The aim of our study was to determine whether the P2X7 receptors affect fluid secretion in pancreas, salivary glands and tear glands. We monitored gland secretions in in vivo preparations of wild-type and P2X7,/, (Pfizer) mice stimulated with pilocarpine. In cell preparations from pancreas, parotid and lacrimal glands we measured ATP release and intracellular Ca2+ activity using Fura-2. The data showed that pancreatic secretion and salivary secretions were reduced in P2X7,/, mice, and in contrast, tear secretion was increased in P2X7,/, mice. The secretory phenotype was also dependent on the sex of the animal, such that males were more dependent on the P2X7 receptor expression. ATP release in all cell preparations could be elicited by carbachol and other agonists, and this was independent of the P2X7 receptor expression. ATP and carbachol increased intracellular Ca2+ activity, but responses depended on the gland type, presence of the P2X7 receptor and the sex of the animal. Together, these results demonstrate that cholinergic stimulation leads to release of ATP that can via P2X7 receptors up-regulate pancreatic and salivary secretion but down-regulate tear secretion. Our data also indicate that there is an interaction between purinergic and cholinergic receptor signalling and that function of the P2X7 receptor is suppressed in females. We conclude that the P2X7 receptors are important in short-term physiological regulation of exocrine gland secretion. [source] 3233: Effectiveness of a new lubricant for dry eye after photoablation using an osmolarity measurementACTA OPHTHALMOLOGICA, Issue 2010B COCHENER Purpose LASIK has been shown to lead to corneal hypoesthesia, which can trigger a decrease in the reflex arc regulating tears secretion. The goal of this study was to evaluate the benefits of a new lubricant after LASIK compared to a classical treatment by measuring tear osmolarity. Methods Twenty patients scheduled to undergo LASIK were enrolled in the study and randomized into two groups. A baseline osmolarity measurement was taken (TearLab Osmolarity System, TearLab Corp) and then randomized into one of two groups. Patients in the first group received two artificial tears (Refresh and Celluvisc, Allergan) following surgery while the 2nd group received a PEG 400 and hylauronic acid (HA) artificial tear (Blink, Abbott Medical Optics) following treatment. These patients were assessed at 1 month postoperative for changes in osmolarity. Results Normal values of osmolarity with Tear Lab range between 275 and 308 mOsm/L; above this, we consider that the eye is dry. The single tear treatment had the same efficiency as our standard two-drop therapy. No side effects were noted in any patients. Most patients found it easier to have only one kind of lubricant instead of a combination of two, which lead to a better observance. The use of the tear osmolarity system provided a quick, reliable test for detecting patient with a risk of postoperative dry eye and for assessing the effectiveness of the therapy. Conclusion The new lubricant, Blink, is another choice in the therapeutic panel for treatment of dry eye disease. It is well tolerated and as efficient as the combination of Refresh and Celluvisc. New osmolarity measurement is an easy, fast and non-invasive well tolerated test for detecting infraclinical dryness especially before refractive surgery. [source] | ||||||||||