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Biomedical subjects

M W Greaves

Publications and source records attributed to M W Greaves.

At least 235 records · Page 13Linked to original sources
PubMed1982

[Prostaglandins, leukotrienes, anti-inflammatory substances and their importance in inflammatory reactions of the skin].

Prostaglandins appear to play an important role as mediators of inflammation since they fulfill the major criteria. They possess powerful proinflammatory properties; they are present in increased concentrations in a wide range of proinflammatory lesions, and anti-inflammatory drugs inhibit their formation. The role of leukotrienes and other hydroxy fatty acid products is far less clear although their participation in cellular events seems probable. Steroid and nonsteroid anti-inflammatory drugs owe their activity at least in part to inhibition of biosynthesis of prostaglandins, although these two drug classes appear to act at different points in the pathways. It becomes increasingly clear that the oxygenation of arachidonic acid leads to the formation of a multiplicity of pharmacologically active fatty acids of which only a few have so far been identified.

Animals↗
PubMed1981

Adenosine triphosphate-evoked vascular changes in human skin: mechanism of action.

Adenosine triphosphate (ATP), adenosine diphosphate (ADP), adenosine monophosphate (AMP), adenosine, adenine and inosine were injected intradermally into the backs of human volunteers. ATP, ADP and AMP evoked weal and flare responses in the skin in a dose dependent manner. The rank order of potency was ATP greater than ADP greater than AMP; other metabolites were apparently inactive. The potency of ATP was approximately 0.002 times that of histamine. In the forearm, cross tachyphylaxis was demonstrated between ATP and histamine weals; also the flare due to injected ATP spread beyond a band which was applied to prevent diffusion, indicating that the flare is neurogenic. Injections of ATP and high doses of ADP produced a sensation of persistent pain, unlike histamine which produced transient pain or itch on some occasions, and saline which was without effect. The possible involvement of histamine, mast cells and prostaglandins in the response was examined. The inhibitory actions of systemic pretreatment with diphenhydramine suggests that the erythema and wealing responses to ATP are at least partly due to ATP-evoked histamine release. Indomethacin, doxantrazole and cimetidine did not alter the ATP reaction.

Adenosine Diphosphate↗
PubMed1981

Aquagenic pruritus.

Three patients were studied in whom brief contact of the skin with water at any temperature evoked intense itching without visible changes in the skin. The patients were otherwise apparently healthy, and this chronic and disabling disorder tended to attract a "psychogenic" label. Pharmacological studies showed that the condition was associated with local release of acetyl choline in the skin, mast-cell degranulation, and raised blood histamine concentrations. It responded well to antihistamines in two of the three patients. Aquagenic pruritus is probably common, but it is generally unrecognised and may be misdiagnosed. Antihistamines may induce a good therapeutic response.

Acetylcholine↗
PubMed1981

Relapse rate and long-term management of plaque psoriasis after treatment with photochemotherapy and dithranol.

The relapse rate of plaque psoriasis after initial clearing with the "Ingram" dithranol regimen or photochemotherapy was comparable when no maintenance treatment was given. It was estimated that psoriasis recurs to half of its pretreatment extent after about six months in half the patients. Maintenance treatment with photochemotherapy once a week or once every three weeks was useful in reducing the relapse rate. This study failed to show any statistical difference in relapse rates between these two maintenance schedules. If this finding turns out to be true over longer periods of study the maintenance schedule entailing treatment once every three weeks with its lower cumulative dose of long-wave ultraviolet light will clearly be preferable. The psoriasis in most patients was under better overall control with maintenance treatment than with intermittant clearing courses given when the extent of the psoriasis had become unacceptable to them. There was, however, a group of roughly one-fifth of patients who remained in satisfactory remission for over 16 months after initial clearing. Regular maintenance treatment was unnecessary in them. Much more information is needed on response to treatment in subgroups of patients to permit recognition from the start of which patients are likely to have long remission and which are not.

Adult↗
PubMed1981

The effect of photochemotherapy (PUVA) on cell mediated immunity in the guinea pig.

Guinea pigs were injected intraperitoneally with 8-methoxypsoralen (8-MOP) and afterwards the shaved right flank was irradiated with UV-A. This treatment was performed daily for 14 days. Seven days after treatment started they were immunized with ovalbumin in Freund's complete adjuvant and 7 days later skin tested with ovalbumin on the unirradiated left flank. Photochemotherapy (8-MOP plus UV-A) did not alter the total white blood cells or the proportion of lymphocytes or granulocytes. However, this treatment significantly depressed the delayed hypersensitivity reaction to ovalbumin; nonspecific inflammation, induced by intradermal turpentine, was not altered. In addition, treatment with 8-MOP alone suppressed the skin reaction to ovalbumin, but not to the same extent as treatment with 8-MOP and UV-A. 8-MOP plus UV-A had no effect on macrophage migration inhibition factor but it did significantly depress mitogen and antigen specific lymphocyte transformation.

Animals↗
PubMed1981

Dissociation of histamine release and clinical improvement following treatment of acquired cold urticaria by prednisone.

1 Corticosteroids are known to suppress evoked histamine release from human skin in vitro. Therefore the effect of prednisone, on cold evoked histamine release and clinical response was studied in six patients with acquired cold urticaria. 2 Following cold challenge all six patients developed an immediate urticarial response of the forearm and elevation of histamine levels, measured by superfusion cascade bioassay of the venous blood draining the forearm. 3 After treatment with prednisone, in an oral dose of 20-25 mg for 1 to 5 days, a suppression of evoked histamine release occurred in all but one patient. However, there was no corresponding decrease of erythema or oedema, though pruritus was improved in most patients. 4 The lack of clinical improvement in erythema and oedema, despite reduction in histamine levels, suggests that histamine may not be the principal mediator of the vascular response to cold challenge in acquired cold urticaria.

Adolescent↗
PubMed1981

Cholinergic urticaria with associated angio-oedema.

Three patients are described who developed angio-oedema and urticaria after a hot bath challenge and physical exercise. In one patient this was accompanied by a fall in peak expiratory flow rate. Blood levels of smooth muscle biological activity, measured using a bio-assay, increased in all patients after experimental challenge. The association of angio-oedema with cholinergic urticaria is emphasized and possible mechanisms discussed.

Adolescent↗
PubMed1981

Aquagenic urticaria: evidence of cholinergic and histaminergic basis.

Two patients with urticaria evoked at the site of contact of skin with water have been studied. Protection of the skin from contact with water by prior application of petrolatum ointment prevented wealing, but removal of the stratum corneum enhanced wealing. Organic solvents did not themselves evoke wealing, but they enhanced the reaction to subsequent challenge by water. That the release of acetylcholine is an essential step in the pharmacogenesis of wealing in aquagenic urticaria is indicated by the suppressive effect of locally-applied scopolamine on water-evoked wealing. Aquagenic urticaria is also associated with elevated blood histamine levels and degranulation of mast cells in the water-challenged skin. The relationship of acetylcholine and histamine to each other and to contact of water with the skin remains uncertain.

Acetylcholine↗