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Biomedical subjects

H A Addo

Publications and source records attributed to H A Addo.

10 recordsLinked to original sources
PubMed1987

Thiazide-induced photosensitivity: a study of 33 subjects.

The clinical features, action spectrum and subsequent course, are described in 33 subjects with thiazide-induced photosensitivity. The reaction appeared to be phototoxic in nature. The wavelengths involved were those of the longer UVA and, not infrequently, also the shorter UVB waveband. In most instances withdrawal of the drug resulted in clearance of the clinical reaction and a return of the action spectrum to normal. In the few subjects in whom the photosensitivity persisted, either in the form of the clinical reaction or an abnormal action spectrum, or both, either a specific photodermatosis was present or another potentially photoactive drug was being taken. In no instance, was there evidence of the induction of long-term chronic photosensitivity (persistent light reaction) following the withdrawal of the thiazide drug.

Aged↗
PubMed1987

UVB phototherapy and photochemotherapy (PUVA) in the treatment of polymorphic light eruption and solar urticaria.

Forty subjects (36 with polymorphic light eruption and four with solar urticaria) were treated during the spring and early summer of the years 1982 to 1985 with either UVB phototherapy (a total of 54 treatment courses in subjects with polymorphic light eruption) or photochemotherapy (PUVA) (18 treatment courses in polymorphic light eruption and eight in solar urticaria patients). Both forms of prophylactic therapy were found to be effective in 90% of those with polymorphic light eruption, and PUVA in all those with solar urticaria. The optimum duration of treatment was 5 weeks. Adverse reactions, although common, were usually slight and rarely required alteration of the treatment regimen.

Adolescent↗
PubMed1987

Quinine induced photosensitivity: clinical and experimental studies.

Quinine induced photosensitivity, an infrequently described adverse effect, is reported in four patients. The clinical presentation and distribution was that of a light exposed site eruption characterized by oedema and erythema in three patients, and by lichen planus in the fourth. Monochromator phototesting demonstrated abnormal delayed erythema responses in the UVB, UVA and visible wavebands. The clinical features suggested a phototoxic effect but laboratory studies indicated that the molecular mechanisms involved are unusual. Clinical and phototest evidence of abnormal photosensitivity persisted for some months after stopping quinine. Broad spectrum sunscreens are advised for the management of such patients and, where possible, cessation of quinine administration.

Aged↗
PubMed1985

A study of cutaneous photosensitivity induced by amiodarone.

Amiodarone-induced cutaneous photosensitivity was studied in 12 subjects treated with the drug. The action spectrum for the abnormal response to sunlight was shown to be within the range of 335-460 (+/- 30) nm. The clinical features of the photosensitivity response suggested that it was most probably a phototoxic reaction, a conclusion supported by the results of in vitro studies which indicated activity mainly against cell membranes. Of the five in vitro models used, three--namely photohaemolysis, the inhibition of DNA synthesis in PHA stimulated lymphocytes and the killing of mouse peritoneal macrophages--provided unequivocal evidence of the phototoxic potential of both amiodarone and its major metabolite, desethylamiodarone. In each model desethylamiodarone produced a greater effect by a factor of between 2 and 10. In vitro, UV-B wavelengths produced a greater effect than UVA but the difference between the effective wavelengths in vivo and in vitro might be explained by the greater absorption of the shorter wavelength UV-B in the epidermis. Zinc oxide-containing preparations appeared to be the most effective in reducing the cutaneous photosensitivity. It is suggested that the long-term cutaneous pigmentation resulting from oral amiodarone has a significant photosensitivity component.

Adult↗
PubMed1985

A study of compositae plant extract reactions in photosensitivity dermatitis.

In subjects with chronic photosensitivity of the photosensitivity dermatitis/actinic reticuloid type the persistent reaction of the skin appears to be due to a number of factors, including those of contact allergic sensitivity and of photosensitivity (i.e., phototoxicity and/or photoallergy). The assessment of the relevant importance of these factors can be complicated by the reactivity of the skin resulting in false positive responses from skin patch and photopatch testing. Moreover, difficulties may also arise in the assessment of the results using commercially available patch test materials. However, the study described here indicated that, provided the reactivity of the skin is suppressed prior to investigation, reliable results are obtained from photopatch testing and that these results are similar whether the extract is from a commercial source or has been obtained from locally grown Compositae plants. Also, that although there may be a photoallergic component in the cutaneous photosensitivity, the results of the in vivo and in vitro studies reported here indicate the likely involvement of phototoxicity as well.

Adult↗
PubMed1984

Actinic prurigo--a specific photodermatosis?

Actinic prurigo can be defined as an idiopathic photodermatosis which usually starts in childhood, particularly affects the female, with some evidence for an atopic and familial photosensitivity background. It affects both exposed and covered skin but mainly the former and although it may be present all the year round is usually maximal on the exposed skin during months of sunshine. The changes are those of a chronic prurigo along with more acute episodes following sunshine exposure in which there is a background of edematous erythema. It usually lasts throughout childhood and adolescence, but tends to wane and even to clear in late adolescence or early adult life. The etiology is unknown, as are the mechanisms involved. Action spectrum studies have produced no evidence for the involvement of specific wavelengths other than the presence of UV sensitivity in some subjects and a suggestion that the longer wavelength UVA may be more important than the sunburn waveband around 305 nm. Based on a study of 60 personal cases with actinic prurigo the authors agree with the longheld view of Calnan & Meara (1) that actinic prurigo is a separate and distinct photodermatosis.

Adolescent↗
PubMed1982

The relationship between exposure to fragrance materials and persistent light reaction in the photosensitivity dermatitis with actinic reticuloid syndrome.

Contact allergic sensitivity to allergens such as plants of the Compositae family is a feature of the chronic skin reaction seen in the photosensitivity dermatitis with actinic reticuloid syndrome. In fifty patients with this syndrome an increased incidence of contact allergic sensitivity to some common fragrance materials was demonstrated. Evidence is also presented, both by in vitro and in vivo studies, which indicates that a phototoxic mechanism is involved. The relevance of continued exposure to common allergens and their involvement in photosensitization mechanisms is discussed in an attempt to explain the state of 'persistent light reaction'.

Humans↗