Library

feed icon rss

Your email was sent successfully. Check your inbox.

An error occurred while sending the email. Please try again.

Proceed reservation?

Export
Filter
  • 1980-1984  (2)
  • Age-dependent maturation  (1)
  • Allergen-induced histamine release  (1)
  • 1
    ISSN: 1432-1076
    Keywords: Bronchial asthama ; Adrenergic theory ; α- and β-adrenoceptors ; Blood cells ; Age-dependent maturation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Among the possible mechanisms which may cause wheezing or asthmatic episodes a genetically determined β-adrenoceptor blockade and a hyperresponsiveness of α-andrenoceptors has been postulated. Evidence to support this hypothesis stems from an increased bronchial sensitivity to β-blockers, a reduced formation of cyclic AMP in response to β-adrenergic stimulation and enhanced α-adrenergic responses in asthmatic subjects. The recent development of techniques for measuring the specific, high-affinity binding of radiolabeled α-and β-adrenergic antagonists made it possible to study α- and β-adrenoceptors in vitro. Based upon the assumption that a change in the number and/or affinity of adrenergic receptors might be a general phenomenon, we have performed α- and β-receptor binding studies on lymphocytes and platelets from wheezing infants and asthmatic children as well as of infants, children, and adults not suffering from these diseases. Using 125[I]-cyanopindolol (ICYP) and 3[H]-yohimbine (HYOH) as highly specific ligands for α- and β-adrenoceptors, the following results were obtained: (1) Lymphocytes and platelets from control subjects and asthamatics bound similar amounts of ICYP and HYOH and thus showed no differences either in the number or the affinity of α- and β-adrenoceptors. Lymphocytes and platelets of wheezing and nonwheezing infants also bound the same amounts of the radioligands. (2) In asthmatic children receiving 4×2 puffs salbutamol β-adrenoceptor were down-regulated and this may mimic β-adrenoceptor blockade. (3) When subjects were divided into four categories according to age (0–5, 5–10, 10–20 years, adults) the number of β-adrenoceptor binding sites showed an age-dependent increase. The number and affinity of α-adreneceptor binding sites on platelets was neither influenced by age nor disease. It is concluded that the α- and β-adrenoceptors of wheezing infants and asthmatic children at least on blood cells are normal. However the β-adrenoceptors show an age-dependent maturation process, which may account for an unresponsiveness to β-adrenoceptor agonists in wheezing infants.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 2
    ISSN: 1432-1440
    Keywords: Childhood asthma ; House dust mite allergy ; Bronchial provocation test ; Allergen-induced histamine release ; Basophile granulocytes
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary It was suggested that 28 asthmatic children be sensitized against the house dust mite according to a positive case history and/or a positive result of the prick test and the radio-allergosorbent test (RAST). When these children underwent a bronchial provocation test with house dust mite allergen, 19 responded with a bronchoconstriction whereas nine remained unaffected. With the positive results there occurred a good correspondence with case history, prick test, and RAST, the latter being most valid in predicting results of bronchial reagibility to the house dust mite. On the other hand, those children who underwent bronchial provocation due to positive results in at least one of the allergy tests, but who did not respond with bronchoconstriction, showed no correspondence with either history or skin testing and RAST. However, when isolated basophiles from both children's groups were challenged with different house dust mite concentrations, the histamine release not only showed a good correspondence with the positive results of the bronchial provocation test, but also a correct prediction of the negative results could be made. Thus, of all allergy tests, the histamine liberation test appears to be the most valid for predicting the bronchial reagibility of asthmatic children to the house dust mite; this perhaps will allow a reduction in the frequency of inhalation challenges in those asthmatic children who are supposed to have been sensitized against house dust mite.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
Close ⊗
This website uses cookies and the analysis tool Matomo. More information can be found here...