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Query: UMLS:C0033774 (pruritus)
 14,546 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Atopic dermatitis (AD) is a familial inflammatory skin disorder which is characterized by extreme pruritus, the typical morphology and distribution, the chronic or chronically relapsing time course and the personal or family history of atopy (asthma, allergic rhinitis, atopic dermatitis). However, there exists a variety of additional features which are either less specific or relatively rare. Although this disease has been well-known since the beginning of the century, the pathogenesis is not clearly understood at present. This review summarizes the reported deviations of the immune system as well as the alterations of the mediators of inflammation and the abnormalities of cyclic nucleotide regulation. These findings will be correlated with clinical symptoms. In particular the following topics were taken into consideration: association with HLA-antigens, elevation of serum IgE and generation of IgE immune complexes, numerical and functional deficiencies of T-suppressor cells, involvement of granulocytes, alterations of mediators of inflammation and especially the observations on the cyclic adenosine monophosphate (cAMP)-phosphodiesterase. These extremely complex findings based on the interaction between disregulation of the autonomous nervous system and alterations of the immune system may provide a better understanding of the pathogenesis of atopic dermatitis.
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PMID:[Pathogenesis of atopic dermatitis]. 299 74

Atopic dermatitis is clearly characterized by altered cutaneous physiologic responses. There is a tendency to acral vasoconstriction. Rubbing causes skin pallor and white dermographism. Vascular instability is demonstrated by responses to cholinergic agents, histamine, and nicotinates. Psychophysiologic studies demonstrate exaggerated vasodilator responses to emotional stress with consequent pruritus and scratching. The itch threshold is low, duration is prolonged, and nighttime scratching movements may be frequent or almost continuous. Regardless of the inciting trigger factors, the scratching causes the damage and the severe dermatitis. Thermal as well as emotional stimuli to sweating cause severe itching in AD, yet the concept of a miliaria-type, poral occlusion mechanism remains unproven. Some studies suggest actually increased sweating along with erythema and pruritus during acute flares of AD. The concept of sweat-borne allergens causing skin reactions during sweating is interesting but has never been proven. Studies of sweat responses to pharmacologic agents have produced conflicting data, and attempts to link these responses to Szentivanyi's beta-adrenergic blockade theory are not convincing. The numerous variables of climate, season, sex, age, and habitus affect sweating greatly. Future studies must carefully control for each of these factors before pharmacologically induced sweat responses can be interpreted clearly. A number of lines of evidence suggest involvement of histamine and other mediators in the evolution of erythema, pruritus, and scratching in AD. Flares of the condition have been reproducibly evoked by only two incitants: experimental emotional stress interviews and specific food challenge in selected sensitive individuals. In the latter, increased plasma histamine has been demonstrated, presumably generated by antigen/IgE stimulated degranulation of mast cells in the gut and/or skin. The demonstrated increased histamine releasability of basophils from atopic individuals may be the result of defective cellular regulatory mechanisms. Recent studies have demonstrated increased cyclic AMP-phosphodiesterase activity in leukocytes from atopic individuals. The resultant decreased intracellular cyclic AMP removes an inhibitory factor, which in turn causes net cellular hyperresponsiveness. This effect has been shown to account, at least in part, for increased histamine release from leukocytes of patients with AD. These and other studies focused upon cell functional regulation are providing better understanding of basic biochemical abnormalities and may lead to improved diagnostic and therapeutic approaches in managing atopic disease.
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PMID:Pharmacophysiology of atopic dermatitis. 300 74

The term hyper-reactivity defines an inadequate reaction of the nose to normal airborne stimuli that are harmless to most of the population. In such cases the nose always shows exactly the same symptoms, irrespective of whether the rhinitis is allergic (IgE- or cell-mediated) or nonspecific (vasomotor). These symptoms include sneezing, nasal obstruction, hypersecretion, and itching of the nose. The vascular supply of the nose consists of capacitance vessels (veins, venules, sinusoids), resistance vessels (arteries, arterioles), and exchange vessels (capillaries of fenestrated types). Drug and mediator effects may be directed to different nasal vessel systems. The autonomic innervation of the nose is complex. Some neuropeptides have been demonstrated, in addition to the classical neurotransmitters of the sympathetic and parasympathetic system. Neuropeptide Y (NPY) is found in adrenergic fibers, vasoactive intestinal peptide (VIP) in cholinergic neurones; substance P (SP), calcitonin-gene-related peptide (CGRP) and neurokinine (NKA) are found in sensory nerves. The possible significance of the different neurotransmitters and mediators in nasal hyperreactivity is discussed.
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PMID:[Current aspects of nasal hyperreactivity]. 306 18

Most helminth parasites induce a strong IgE antibody and elevated eosinophil response in their mammalian hosts and a number of in vitro studies have suggested that IgE, possibly in association with eosinophils, may be an essential element of the host protective immunity against helminth infections. To assess the role of IgE in protective immunity, we examined the effect of suppressing the IgE antibody response on rat immunity to Schistosoma mansoni. Suppression was achieved in neonates by injections of rabbit anti-epsilon chain gamma-globulins, control rats received injections of unspecific gamma-globulins. IgE suppression caused a marked reduction of the inflammatory reaction that developed in the skin of immune rats at the site of a cercarial challenge: the early (30 to 60 min) wheal and flare reaction was abolished, and the late cutaneous reaction (6 to 18 h) associated with intense pruritus, edema and local eosinophilia was greatly reduced. This shows that IgE was critical to the recruitment of effector cells and molecules in the skin during the first 24 h following parasite invasion. Worms were recovered 18 to 30 days after a primary infection and 18 days after a challenge infection from IgE-suppressed and control rats. IgE-suppressed rats cured a first infection as rapidly as the control rats; however, they were two to three times less efficient than the controls at eliminating a second or a third challenge. These observations demonstrate that IgE antibodies are essential for the full development of rat acquired protective immunity against Schistosoma mansoni.
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PMID:IgE antibody and resistance to infection. II. Effect of IgE suppression on the early and late skin reaction and resistance of rats to Schistosoma mansoni infection. 308 55

A 29-year-old man with pollen allergy had experienced immediate adverse reactions, such as itching of the eyes, rhinitis, wheezing, and general urticaria, after using disodium cromoglycate (DSCG) eye drops. The local symptoms were reproducible, and skin tests were strongly positive. With serum from the patient, a RAST was developed for the assay of IgE antibodies. The uptake on RAST disks was 6% of the total activity added, which was a significantly higher level than was found in sera from 35 randomly selected blood donors or in sera from 25 patients tolerating DSCG. By addition of DSCG to the patient's serum, 95% of the binding to paper disks could be inhibited. The induction of specific IgE antibodies was proposed to be a result of a combination of electrostatic and hydrophobic interaction of DSCG and a protein carrier. The substance would thus act as a hapten without any covalent binding to the carrier. DSCG may serve as a model for other nonreactive low-molecular-weight substances suspected to elicit type I-like adverse reactions.
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PMID:Assay of specific IgE antibodies to disodium cromoglycate in serum from a patient with an immediate hypersensitivity reaction. 312 91

This study was performed to investigate the inflammatory changes occurring in the human conjunctiva at different time periods after allergen provocation. Twenty-three ryegrass-sensitive patients with allergic conjunctivitis (19 with hayfever and four with vernal conjunctivitis) were challenged by topical administration of ryegrass antigen to the eye. Allergen concentrations were increased in increments until an immediate ocular allergic reaction was elicited. Numbers of various inflammatory cells (neutrophils, eosinophils, lymphocytes, and monocytes) found in conjunctival scrapings were quantified and correlated with the clinical profile, total serum IgE, and serum IgE to Rye I antigen. Twenty minutes after some level of antigen topical challenge to the eye, all patients had ocular redness, tearing, and itching. Compared with findings in seven control subjects, significant inflammatory cells were found in the conjunctival scrapings of patients before challenge (p less than 0.05) and 20 minutes (p less than 0.001) and 6 hours (p less than 0.002) after effective challenge. Significant increases in neutrophils of patients occurred after 20 minutes (p less than 0.001), and in eosinophils at 6 hours (p less than 0.005), compared with values of control subjects. When each case was evaluated individually, nine of the 23 patients had highly evident inflammatory changes 6 hours after allergen provocation. The levels of total serum IgE and serum IgE to Rye I antigen of these nine patients did not differ significantly from the other patients in the study. Our data provide the first evidence in humans that significant inflammatory changes in conjunctival scrapings are present long after allergen exposure has ended.
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PMID:Inflammatory changes in conjunctival scrapings after allergen provocation in humans. 229 2

During her 26th week of pregnancy a 20-year-old woman developed generalized pruritus, urticaria, flushing, tinnitus, and tachycardia during plasmapheresis with 5% human serum albumin (HSA) as adjunctive treatment for anti-Kell isoimmunization. The reaction was controlled with intravenous diphenhydramine. Despite pretreatment with diphenhydramine and betamethasone a subsequent attempt to perform plasmapheresis with infusion of 5% HSA resulted in a more severe reaction which progressed to respiratory distress. Intradermal skin testing with 5% HSA produced a 9 x 11-mm wheal and 17 x 21-mm erythema at 15 minutes. An enzyme-linked immunoassay was positive for IgE antibody to 5% HSA before and after dialysis for removal of Na caprylate. These results are consistent with an IgE-mediated basis for this patient's reaction to HSA.
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PMID:Anaphylaxis to human serum albumin. 230 85

The Restaurant syndromes can be caused by five major factors: food allergens, sulfites, monosodium glutamate (MSG), tartrazine, and scombroidosis (and other seafood poisoning). A history of atopy and ingestion of known food allergens such as peanuts, egg, fish, and walnuts, together with positive results of skin tests or RAST to these foods, will favor a diagnosis of food allergy. Allergic reactions to peanuts have produced fatalities in minutes through an IgE mediated reaction. An extremely rapid onset (minutes) of symptoms consisting of flushing, bronchospasm and hypotension is consistent with a sulfite reaction. Burning, pressure, and tightness or numbness in the face, neck, and upper chest following ingestion of Chinese food favors a diagnosis of adverse reaction to MSG. Also, development of late onset bronchospasm (up to 14 hours) may be related to MSG reactions. Bronchospasm and urticaria in a patient with a history of aspirin intolerance suggests tartrazine sensitivity. If everyone ingesting a fish meal develops flushing, urticaria, pruritus, gastrointestinal complaints, or bronchospasm, this implies scombroidosis, ciguatera, or other seafood poisoning. Finally, severe headache or hypertension can result from ingestion of naturally occurring amines, such as tyramine (cheese, red wine) and phenylethylamine (chocolate). A double-blind oral challenge test may be the only way of confirming the diagnosis for most of the etiological factors of the Restaurant syndromes. The treatment of choice for acute reaction is epinephrine followed by antihistamine. Proper labeling and avoidance of these ingredients in sensitive individuals are the best preventive measures.
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PMID:The restaurant syndromes. 330 66

Maintenance hemodialysis is widely used throughout the world, and anaphylactic reactions appear to be increasing in number and severity. However, the exact incidence of sensitization and the role of atopy in these reactions are not yet fully understood. All of the 111 patients routinely dialyzed in a center were tested. All patients had a complete investigation of atopy, RAST to chemicals released during the procedure of dialysis (ethylene oxide (Eto), formaldehyde, phthalic anhydride, and toluene diisocyanate), skin tests with the effluent, and the titration of blood eosinophils. The incidence of atopy was found to be lower (13.5%) than in the normal population of the area. Skin tests with either histamine or allergens are significantly (p less than 0.001) smaller than those of nondialyzed subjects, and this method does not appear to be ideal in this population of patients. Eto sensitivity ranked first (5.5%), followed by phthalic anhydride sensitivity (3.6%); 5/6 patients who had a sensitivity to Eto and/or phthalic anhydride presented symptoms during dialysis, but they never were life threatening. Formaldehyde RAST was only found in one patient who had a life-threatening reaction. Finally, three patients presenting pruritus had positive skin prick tests with the effluent of the dialyzer. All patients having a first use syndrome and 80/81 symptom-free patients did not have serum-specific IgE against the released chemicals, 5/17 patients who had a pruritus during dialysis had either positive RAST to released chemicals or skin tests to the effluent, 5/8 patients who suffered from anaphylaxis had positive RAST to released chemicals, but only those who had a positive RAST presented a severe reaction.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Allergy in long-term hemodialysis. II. Allergic and atopic patterns of a population of patients undergoing long-term hemodialysis. 334 88

Thirty individuals with history of immediate, objective, adverse reactions after shrimp ingestion underwent double-blind, placebo-controlled shrimp-food challenges. All individuals who did not exhibit a positive response (reproduction of objective symptoms) were administered an open challenge of 16 whole cooked shrimp. Positive challenge responses occurred in 9/30 subjects (30%); six of these subjects experienced a positive response during the double-blind phase. Of the 21 remaining subjects, 12 experienced generalized pruritus as their only symptom, whereas nine subjects had completely negative challenge responses. All placebo challenges were negative. Although a positive skin test was strongly associated with challenge symptoms (p less than 0.001), the shrimp prick skin test titration end points were not different among the challenge groups. The serum shrimp RAST percent was significantly higher in the positive challenge group (p less than 0.02). Mean levels of shrimp-specific serum IgG, IgA, and IgM levels were not different among the challenge groups. Although no single immunologic variable could be consistently used to identify subjects more likely to exhibit a positive challenge response, the composite of a positive shrimp prick skin test and elevated serum shrimp-specific IgE (RAST percent label bound greater than 11%) demonstrated a correct predictive value of 87% in this group of shrimp-sensitive subjects.
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PMID:Provocation-challenge studies in shrimp-sensitive individuals. 337 30


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