Mast Evans

Content:
  • Error 500 - Page not Available
  • Kevin W Evans CPA - Mast Evans & Isenhour LLP 2nd St SW Conover, NC Accountants - MapQuest
  • Mast Evans & Isenhour LLP 2nd St SW, Conover, NC - omosironews.info
  • Mast Group Ltd. Providing high quality diagnostic products to customers worldwide
  • Action of mast cell dischargers on the localization of Evans' blue. - PubMed - NCBI
  • The Mast Brothers-I just want to please the Lord

    Error 500 - Page not Available

    mast evans Mast cells are involved in atopic disorders, often exacerbated by stress, and are located perivascularly close to sympathetic and sensory nerve endings. Mast cells are activated by electrical nerve stimulation and millimolar concentrations of neuropeptides, such as substance P SP. Moreover, acute psychological stress induces CRH-dependent mast cell degranulation. Treatment of rats neonatally with capsaicin had no effect on either Evans blue extravasation or mast cell degranulation, indicating that the effect e techno exogenous CRH in the skin was not secondary to or dependent on the release of neuropeptides from sensory nerve endings. The effect of CRH on Evans mast evans extravasation and mast cell degranulation was inhibited by the mast cell stabilizer disodium cromoglycate cromolynbut mast evans by the mast evans molecule somatostatin.

    Kevin W Evans CPA - Mast Evans & Isenhour LLP 2nd St SW Conover, NC Accountants - MapQuest

    mast evans

    Mast cells are involved in atopic disorders, often exacerbated by stress, and are located perivascularly close to sympathetic and sensory nerve endings.

    Mast cells are activated by electrical nerve stimulation and millimolar concentrations of neuropeptides, such as substance P SP.

    Moreover, acute psychological stress induces CRH-dependent mast cell degranulation. Treatment of rats neonatally with capsaicin had no effect on either Evans blue extravasation or mast cell degranulation, indicating that the effect of exogenous CRH in the skin was not secondary to or dependent on the release of neuropeptides from sensory nerve endings.

    The effect of CRH on Evans blue extravasation and mast cell degranulation was inhibited by the mast cell stabilizer disodium cromoglycate cromolyn , but not by the antisecretory molecule somatostatin. To investigate which vasodilatory molecules might be involved in the increase in vascular permeability, the CRH injection site was pretreated with the H 1 -receptor antagonist diphenhydramine, which largely inhibited the CRH effect, suggesting that histamine was involved in the CRH-induced vasodilation.

    The possibility that nitric oxide might also be involved was tested using pretreatment with a nitric oxide synthase inhibitor that, however, increased the effect of CRH. These findings indicate that CRH activates skin mast cells at least via a CRHR 1 -dependent mechanism leading to vasodilation and increased vascular permeability. The present results have implications for the pathophysiology and possible therapy of skin disorders, such as atopic dermatitis, eczema, psoriasis, and urticaria, which are exacerbated or precipitated by stress.

    CRH is also secreted peripherally and has proinflammatory and other actions 1. For instance, systemic administration of rabbit anti-CRH serum suppressed both the amount of exudate and inflammatory cell accumulation in carrageenin-induced sc inflammation and ameliorated the severity of experimental autoimmune uveitis in rodents 2 , 3.

    Immunocytochemistry verified the presence of CRH also in human tissues undergoing inflammatory processes, including joints of patients with rheumatoid arthritis and osteoarthritis, thyroids of patients with Hashimoto thyroiditis, and gut lesions of patients with ulcerative colitis 4 — 6. However, there is a discrepancy between the abundance of iCRH and the paucity of its mRNA at inflammatory sites in the early, acute phase of inflammation.

    The demonstration of CRH-like immunoreactivity in the dorsal horn of the spinal cord and dorsal root ganglia 9 , 10 , as well as in sympathetic nerve cell bodies in sympathetic ganglia 9 , 11 , support the hypothesis that the majority of iCRH in early inflammation is of neuronal rather than immune cell origin. CRH administration to humans or animals iv causes significant dose-dependent peripheral vasodilation, manifested as flushing and hypotension These effects may derive from activation of mast cells, which are located perivascularly, close to nerves for review see Ref.

    In fact, acute psychological stress in rats resulted in dura mast cell activation and rat mast cell protease I secretion, which were CRH-dependent Mast cells can be activated by nerve stimulation 15 or sensory neuropeptides such as SP 16 , and they secrete potent vasoactive and proinflammatory mediators that include histamine, cytokines, prostanoids, and proteases The ability of CRH to activate mast cells may explain its proinflammatory actions and the pathophysiology of certain skin conditions, which are precipitated or exacerbated by stress, such as atopic dermatitis, eczema, psoriasis, and urticaria.

    Here we studied the ability of CRH to activate skin mast cells and increase vascular permeability in a receptor-specific, dose-dependent fashion. The drugs used were obtained from the following sources: All solutions, except antalarmin see below , were prepared fresh in normal saline the morning of the experiment. Male Sprague Dawley rats, each weighing approximately g Charles River, NY , were anesthetized with a single ip injection of 0. The same procedure was repeated with 0.

    The W geno-type was inferred from the white coat depletion of hair pigment of the animals. All animals were housed in a modern animal facility and were allowed ad libitum access to food and water. Drugs were tested by intradermal injection in 0. The CRH was drawn in one syringe while, when appropriate, the pretreatment solutions were prepared in different syringes to avoid any mixing between the two solutions. The pretreatment solution was injected first and was allowed to remain in the skin for 5 min before CRH.

    The final amount injected was 0. The animal was killed 15 min later by asphyxiation over CO 2 vapor and decapitated; the skin was removed, turned over, and photographed. Animals were handled one at a time in an isolated procedure room inside the animal facility to minimize any effect of the stress of handling, change of environment, or presence of other injected animals. For sensory nerve neuropeptide depletion, one entire litter of rats was injected with capsaicin within 2 days of birth, and the male rats were used 5 weeks later as described before The effectiveness of this procedure was confirmed by immunocytochemistry 21 , which showed that there were no SP-positive cells or nerve processes in the skin of capsaicin-treated rats.

    All specimens were treated with 0. The sections were incubated for 2 h at 4 C in rhodamine-conjugated goat antirabbit immunoglobulin Cappel Laboratories, Cochranville, PA , diluted 1: Final observation and photography were performed with Nikon Diaphot inverted microscope Don Santo. Human leukemic mast cells HMC-1 were obtained from Dr. Butterfield Mayo Clinic, MN and were grown as described previously Two successive amplifications were conducted using overlapping, nested primers.

    Primer selection was based on the published sequence of CRHR 1 The number of animals tested in vivo or in vitro is denoted by n. The effect of CRH on both vasodilation and mast cell degranulation was dose dependent Table 1.

    Little intrarat variability was observed during these experiments 3. To examine the possible confounding effect of such variability, the results were recalculated after subtracting the control value obtained from the saline injection in each rat. C, The same results shown in B but recalculated after subtracting the control value due to saline from all experimental values obtained in the same rat. The inhibitory effect of antalarmin required 6 h to become evident results not shown , most likely because it was extremely insoluble in aqueous medium.

    B, Agarose gel 1. No such product was identified in human cultured synoviocytes used under the same conditions results not shown. Ultrastructural observations of mast cells from CRH-injected sites had obvious signs of degranulation evidenced by loss of the electron dense content of their secretory granules Fig.

    Photomicrographs of rat skin mast cells stained with toluidine blue. Higher magnifications of mast cells from C a control site and D a CRH site; note activated mast cells in D showing secretory granule content outside the cell perimetry.

    Actual number of rats examined is listed on Table 1. In animals that had been treated neonatally with capsaicin to destroy neuropeptide containing sensory nerve termini, immunohistochemistry for SP showed no fibers positive for this peptide Fig. We also investigated whether the effect of CRH could be inhibited by agents known to either stabilize the mast cell surface or inhibit neuronal secretion. To investigate which mast cell-derived vasodilatory molecule mediated the vasodilatory effect of CRH, the injection sites were pretreated with the histamine-1 receptor antagonist diphenhydramine for 5 min Fig.

    These results suggest that, whereas histamine is the main molecule through which CRH induces fluid extravasation, some of this effect may be mediated by other vasodilatory molecules. We, therefore, investigated whether NO might also be involved because it has been shown to be secreted from mast cells. The present findings show that CRH triggers rat skin mast cell degranulation, which results in vasodilation and increased vascular permeability documented by Evans blue extravasation.

    This effect shows little intrarat but considerable interrat variability. The smallest CRH concentration 0. It should also be noted that these peptides carry a net positive charge thought to be important for triggering mast cell secretion, whereas CRH has one net negative charge.

    The vasodilatory effect of CRH was blocked by the antiallergic drug cromolyn, which can inhibit mast cell secretion from connective tissue mast cells 25 , providing indirect evidence that mast cells are necessary. The morphological evidence clearly indicated that CRH results in mast cell degranulation. Somatostatin did not block the effect of CRH on fluid extravasation, but increased vascular permeability itself.

    This is not surprising because somatostatin had previously been shown to stimulate rat 28 and human 29 mast cell secretion. The increase in vascular permeability induced by CRH appears to be receptor mediated because only the amidated form of CRH, which interacts with CRH receptors 30 , was active. The fact that antalarmin did not inhibit the CRH-induced response entirely is most likely due to its insolubility in aqueous media, which results in poor bioavailability.

    Alternatively, CRHR 2 may also be involved. In vivo , some direct action of CRH on blood vessels cannot be precluded because a CRHR 2 subtype was recently identified on arterioles Our finding that the peptide CRH antagonist [ d -phe 12 , Nie 21,38 , Ala 32 ]rCRH 12 — 41 acted as a partial agonist for mast cell degranulation was unexpected.

    We believe that the band seen with RT-PCR in HMC-1 cells does signify CRHR 1 receptor expression in this cell line because it was reliably obtained, whereas no such band was seen when simultaneously run using identical solutions in cultured human synoviocytes obtained from patients undergoing joint replacement.

    Admittedly, it is hard to extrapolate from leukemic mast cells to normal rat skin mast cells and confirmation will have to await in situ hybridization of rat skin samples.

    Nevertheless, our results are supported by other evidence showing that human skin expresses genes for CRH receptors and for CRH The lack of an inhibitory effect of capsaicin treatment on the effect of injected CRH indicates that, at least when given exogenously, the action of CRH does not depend on the presence of sensory afferent fiber terminals or SP release. The identification of CRH in primary sensory afferent fibers 10 , however, suggests that antidromic release of CRH from unmyelinated C fibers innervating the skin may participate in vivo.

    For instance, skin mast cells degranulated in response to electrical stimulation ES of sensory nerves 39 , whereas dura mast cells degranulated after ES of the trigeminal 15 or cervical 40 ganglion. CRH is also present in neurons of sympathetic chain ganglia 41 from the terminals of which it may be also secreted during stress.

    In general, mast cell-neuron interactions appear to be important in hypersensitivity reactions 16 and in neuroinflammatory syndromes CRH binding sites have been found on human peripheral blood leukocytes for review see Ref. Consequently, CRH may either initiate or potentiate the inflammatory process mediated by mast cells via the release of cytokines.

    This possibility is not excluded by our present results since CRH stimulates secretion of IL-1 from monocytes 43 , whereas IL-1 44 and stem cell factor 45 have been reported to induce mast cell secretion. However, inflammatory cells are unlikely to be present under normal conditions in the skin. The fact that the histamine-1 receptor antagonist diphenhydramine could not block the CRH effect entirely indicates that vasodilatory molecules other than histamine may be involved.

    For instance, vasodilation in rodents is equally dependent on histamine and serotonin 46 , whereas cytokines present in mast cells 17 may also be involved.

    For instance, tumor necrosis factor TNF secreted from skin mast cells in response to morphine sulfate was shown to result in skin vasodilation and expression of endothelial adhesion molecule-1 Another vasoactive candidate is NO, which can also be released from mast cells A similar increase in vasodilation following inhibition of NO synthesis by L-NAME documented as increased intestinal permeability and secretion was attributed to release of histamine from mast cells and not to a direct effect of NO In fact, the inducible isozyme of NO synthase is known to be up-regulated in mast cells and macrophages in intestinal inflammation The inflammatory mediators released could recruit and activate immune cells, as well as act on nerve endings to release more peptides, thus further stimulating mast cells.

    Preliminary results indicate that rat skin mast cells degranulate during 30 min of acute stress by immobilization This same process was previously shown to induce degranulation of dura mast cells through CRH release Novel nonpeptide CRH-receptor antagonists, or other molecules that could interfere with CRH-induced skin mast cell activation, might be useful in the management of skin disorders, which are triggered or exacerbated by stress, such as atopic dermatitis, eczema, psoriasis or urticaria.

    Thanks are due to Dr. Linda Tamulaites for her word processing skills. Part of the experimental work reported in this paper was carried out by Dr. Oxford University Press is a department of the University of Oxford.

    It furthers the University's objective of excellence in research, scholarship, and education by publishing worldwide. Sign In or Create an Account.

    Mast Evans & Isenhour LLP 2nd St SW, Conover, NC - omosironews.info

    mast evans

    Mast Group Ltd. Providing high quality diagnostic products to customers worldwide

    mast evans

    Action of mast cell dischargers on the localization of Evans' blue. - PubMed - NCBI

    mast evans