Wheals

The human histamine Hi-receptor is a 487 amino acid protein that is widely distributed within the body. Histamine potently stimulates smooth muscle contraction via Hi-receptors in blood vessels, airways and in the gastrointestinal tract. In vascular endothelial cells, Hi-receptor activation increases vascular permeability and the synthesis and release of prostacyclin, plateletactivating factor, Von Willebrand factor and nitric oxide thus causing inflammation and the characteristic wheal response observed in the skin. Circulating histamine in the bloodstream (from, e.g. exposure to antigens or allergens) can, via the Hi-receptor, release sufficient nitric oxide from endothelial cells to cause a profound vasodilatation and drop in blood pressure (septic and anaphylactic shock). Activation of... 

Urticaria is a usually transient skin reaction marked by edema and the formation of wheals, smooth, raised areas. 

The classical skin response to local release of histamine that results from contact with an allergen, irritant or following an insect bite. A central wheal develops as a direct result of local inflammation and the the oedema the follows the increased capillary permeability caused by histamine acting on HI-receptors on vascular-endothelial cells. 

The nurse should insert the needle at a 15-degree angle between the upper layers of the skin. The nurse should not aspirate the syringe or massage the area Injection produces a small wheal (raised area) on the outer surface of the skin. If a wheal does not appear on the outer surface of the skin, there is a good possibility that the drug entered the SC tissue, and any test results would be inaccurate. 

IMPAIRED SKIN INTEGRITY. The nurse inspects die skin every 4 hours for redness, rash, or lesions that appear as red wheals or blisters. When a skin rash or irritation is present, die nurse administers frequent skin care Emollients, antipyretic creams, or a topical corticosteroid may be prescribed. An antihistamine may be prescribed. Harsh soaps and perfumed lotions are avoided. The nurse instructs the patient to avoid nibbing the area and not to wear rough or irritating clothing. 

The patient is at risk for Stevens-Johnson syndrome when taking the cephalosporins StevensJohnson syndrome is manifested by fever, cough, muscular aches and pains headache, and the appearance of lesions on the skin, mucous membranes and eyes The lesions appear as red wheals or blisters often starting on the face, in the mouth, or on the lips neck, and extremities This syndrome, which also may occur with the administration of other types of drugs can be fatal. The nurse should report any of these symptoms to the primary health care provider immediately. 

Stevens-Johnson syndrome fever, cough, muscular aches and pains, headache, and lesions of the skin, mucous membranes, and eyes. The lesions appear as red wheals or blisters, often starting on die face, in the mo util, or on the lips, neck, and extremities, stomatitis inflammation of die mo util striae lines or bands elevated above or depressed below surrounding tissue, or differing in color or texture subjective data information supplied by the patient or family sublingual under die tongue... 

Figure 5,19. Effect of pipe diameter on pressure drop lor transport of wheal...

Physical factors, such as heat, mechanical stimulation and exercise, may sometimes lead to mast cell degranulation and whealing in the skin, but rarely provoke systemic anaphylaxis [4, 26]. Patients do report that these and other factors in combination (such as exercise, heat and alcohol) may elicit anaphylaxis in summation. 

Some patients with chronic idiopathic urticaria develop wheals and even angioedema after aspirin or NSAIDs. In others, aspirin causes an obvious increase in the underlying urticaria. The reaction may occur in just 15 min or up to 24 h following aspirin ingestion, but on average it develops within 1-4 h. Most cases resolve within a few hours, but in severe reactions bouts of multiform skin eruptions, covering most of the body, may continue for 10 days after aspirin intake [8,16,17]. 

Clough GF, Boutsiouki P, Church MK Comparison 57 of the effects of levocetirizine and loratadine on histamine-induced wheal, flare, and itch in human skin. Allergy 2001 56 985-988. 58... 

Grant JA, Riethuisen JM, Moulaert B, DeVos C A double-blind, randomized, single-dose, crossover comparison of levocetirizine with ebastine, fexofenadine, loratadine, mizolastine, and placebo sup- 59 pression of histamine-induced wheal-and-flare response during 24 hours in healthy male subjects. 

The appearance of erythema or a wheal within 15 min indicates a positive reaction, and calcitonin salmon should not be administered... 

A wheal at least 2x2 mm with erythema is considered positive. 

A wheal at least 6x6 mm with erythema and at least 3 mm greater than the negative control is considered positive. 

TB skin testing with the 5-TU strength of brand purified protein derivative (PPD), also known as the Mantoux test, is the preferred method for skin testing.2,16,20 The product is injected into the skin (not subcutaneously) with a fine (27-gauge) needle and produces a small, raised, blanched wheal to be read by an experienced professional in 48 to 72 hours. Criteria for interpretation are listed in Table 72-1.1,2,6,16,20 The Centers for Disease Control and Prevention (CDC) does not recommend the routine use of... 

Wright, M. and B. Wheals (1987), Pyrolysis-mass spectrometry of natural gums, resins and waxes and its use for detecting such materials in ancient Egyptian cases, /. Appl. Pyrol. 11,195-211. 

Similar results were previously seen with a similar column and a gradient (Ibrahim and Wheals, 1996). Although PEG was not analyzed in this work, nonylphenol ethoxylates eluted after octylphenol ethoxylates, suggesting an alkyl contribution to retention. Since AE s have both a hydrophobic and a hydrophilic section, the alkyl portion may be interacting with the hydrophobic siloxane functionality and the EO portion may be interacting with the hydrophilic silanol functionality of the silica. 

The older test is the pin prick test where a small quantity of the antigen is placed under the skin. If there is an allergic reaction a wheal and flare, i.e. a hive, will appear. The pin prick test is not suitable for those who undergo anaphylactic shock. 

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