Biomedical subjects

Malcolm W Greaves

Publications and source records attributed to Malcolm W Greaves.

6 recordsLinked to original sources

PubMed2003

Itch.

Itch is a common skin sensation, with substantial effects on behaviour. Neurophysiological research has permitted accurate definition of neural pathways of itch, and has confirmed the distinctiveness of itch pathways in comparison with pain. A clinical classification of itch, based on such improved understanding, describes the difference between peripheral (pruritoceptive) and central (neurogenic or neuropathic) itch. New specific and sensitive investigational methods in people and animals enable us to better understand this bothersome symptom, and have important clinical implications. We describe the clinical classification of itch, new findings on neuropathophysiology of itch, methods for assessment, and improved treatments.

Animals↗

PubMed2002

Classification of anti-FcepsilonRI and anti-IgE autoantibodies in chronic idiopathic urticaria and correlation with disease severity.

BACKGROUND: Circulating autoantibodies against FcepsilonRI, IgE, or both occur in approximately one third of patients with chronic idiopathic urticaria (CIU), but not all autoantibodies initiate histamine release. OBJECTIVE: We sought to classify patients with CIU into subsets on the basis of serum bioactivity and immunoreactivity and to examine the relationship between newly defined subtype and disease severity. METHODS: Sera from patients with CIU (n = 78), dermog-raphism (n = 15), and cholinergic urticaria (n = 10) and sera from healthy subjects (n = 39) were analyzed by means of Western blot analysis for anti-FcepsilonRI autoantibodies and for histamine release from basophils and dermal mast cells. In vivo reactivity of autologous serum was tested by means of intradermal injection, and CIU severity was determined on the basis of clinical interview. RESULTS: We classified sera from patients with CIU into 5 subsets: immunoreactive histamine-releasing anti-FcepsilonRI autoantibodies (n = 20 [26%]); immunoreactive anti-FcepsilonRI autoantibodies without histamine-releasing activity (n = 12 [15%]); anti-IgE-like autoantibodies (n = 7 [9%]); serum containing a mast cell-specific histamine-releasing factor (n = 7 [9%]); and sera with no identifiable factor (n = 32 [41%]). Patients with serum histamine-releasing activity had more severe urticaria than patients without such activity. Positive skin test responses to autologous sera were associated with histamine-releasing anti-FcepsilonRI autoantibodies but not with non-histamine-releasing anti-FcepsilonRI autoantibodies. Neither healthy subjects nor patients with dermographism or cholinergic urticaria had his-tamine-releasing anti-FcepsilonRI autoantibodies. CONCLUSION: These data support the specificity of functional anti-FcepsilonRI autoantibodies to CIU. The identification of distinctive subsets of patients suggests that other pathogenic mechanisms occur in CIU in addition to direct ligation of FcepsilonRI by autoantibodies causing dermal mast cell degranulation. Elucidating these mechanisms might lead to new treatments for CIU.

Adolescent↗

PubMed2002

Chronic urticaria.

UNLABELLED: Chronic urticaria has a spectrum of clinical presentations and causes. About 50% of patients with "idiopathic" disease have histamine-releasing autoantibodies in their blood. The term autoimmune urticaria is increasingly being accepted for this subgroup of patients, in whom immunosuppressive therapies may be appropriate if conventional approaches to management are unsuccessful. This article reviews the classification, causes, and management of chronic urticaria in light of recent advances in the understanding of its etiology. LEARNING OBJECTIVE: At the conclusion of this learning activity, participants should have up-to-date knowledge of the classification, assessment, and management of chronic urticaria and understand where the concept of autoimmune urticaria fits into existing frameworks.

Autoimmune Diseases↗

PubMed2002

Pathophysiology of chronic urticaria.

Chronic urticaria includes several different subsets with distinct pathophysiologies, and with important implications for investigation and treatment. Chronic 'idiopathic' urticaria represents a special challenge, which, until recently, was not taken up by dermatological or immunological investigators. However, it has now emerged that at least 30% of patients possess histamine-releasing autoantibodies against Fc epsilon R1, or less commonly IgE itself. These autoantibodies are causative. Recent work implicates complement activation in most cases. Functional (i.e. histamine releasing) autoantibodies are specific to chronic urticaria. However, immunoreactive (non-histamine-releasing) anti-Fc epsilon R1 autoantibodies can be found in sera of patients with physical urticarias and with autoimmune connective tissue and bullous diseases. The reason for the occurrence of this disease type in some individuals but not others is unclear. One possibility is the development, in genetically predisposed persons, of autoantibodies by molecular mimicry - perhaps against lipopolysaccharide of Helicobacter pylori, an organism frequently infecting the upper gastrointestinal tract of chronic urticaria patients.

Autoimmunity↗

PubMed2002

Drug-induced urticaria and angioedema: pathomechanisms and frequencies in a developing country and in developed countries.

A careful drug history should be obtained from all patients with acute or chronic urticaria/angioedema, especially in the elderly. Although strictly comparable data are lacking, drug-induced urticaria appears to be more common in developed countries than in Malaysia, at least in a Hospital setting. Culprit drugs include antibiotics, analgesics and contrast media. Pseudoallergic drug-induced urticaria mimicks true allergic urticaria, but without an evident immunological basis, and is at least as common as the allergic type. In Malaysia, and in many other countries compulsory, ingredient labelling of 'traditional' medicines would do much to reduce the frequency of drug-induced urticaria.

Adolescent↗

PubMed2002

Antihistamines in urticaria and angioedema.

H1-antihistamines are the cornerstone of symptomatic treatment in acute and chronic urticaria, in which they not only relieve itching, but also reduce the number, size, and duration of urticarial lesions. Relief of whealing, flaring, and erythema may be incomplete as the vascular effects of histamine are mediated to its action at H2-receptors as well as at H1-receptors, and other vasoactive substances may also be involved. In randomized, prospective, placebo-controlled, double-blind studies, the new low-sedating H1-antihistamines have been found to be effective and safe in urticaria. Sedating antihistamines, although effective, place patients at risk for adverse effects, including decreased psychomotor performance. The response to H1-antihistamines in some types of urticaria, for example, in urticarial vasculitis, is unsatisfactory. An H2-antihistamine administered concurrently with an H1-antihistamine may modestly enhance relief of itching and wheal formation in some patients with urticaria refractory to treatment with an H1-antihistamine alone. The available evidence does not justify the routine addition of H2-antihistamine treatment to H1-antihistamine treatment.

Angioedema↗