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Biomedical subjects

V Leenutaphong

Publications and source records attributed to V Leenutaphong.

28 records · Page 2Linked to original sources
PubMed1991

Plasmapheresis in solar urticaria.

Three patients with solar urticaria were treated with plasmapheresis. By intradermal injection of in vitro irradiated serum the existence of a circulating photoallergen was demonstrated in cases 1 and 2 but not in case 3. Plasmapheresis induced complete remission of solar urticaria in case 1 and transient improvement in case 2. In case 3, however, no beneficial effect was observed. It is suggested that some patients with solar urticaria, probably those with a circulating photoallergen, may benefit from plasmapheresis.

Adult↗
PubMed1990

Solar urticaria: studies on mechanisms of tolerance.

The mechanisms by which tolerance is induced in solar urticaria were investigated in two patients whose eruptions were induced by wavelengths in the range 320-455 nm in one patient and 400-495 nm in another. Tolerance to radiation was induced by repeated exposures of the skin to the eliciting wavelengths of light. Weal and flare responses to intradermal injections of histamine and the histamine-releasing agent (codeine) were unaltered in the tolerant skin when compared with adjacent normal skin. Intradermal injection of in vitro irradiated serum or plasma from the patients induced an urticarial reaction in the unexposed skin but not in tolerant skin and repeated injections induced tolerance to the eliciting radiation. The results suggest that tolerance is not due to exhaustion of the photoallergen in the skin, or to an increase of the mast-cell degranulation threshold caused by exposure to ultraviolet radiation, or mast-cell mediator depletion, or histamine tachyphylaxis. It is likely that binding sites of IgE on mast cells remain occupied by the photoallergen during the state of tolerance, and that histamine release from mast cells is blocked.

Aged↗
PubMed1989

Pathogenesis and classification of solar urticaria: a new concept.

Although its exact mechanism remains unknown, evidence supports the immunologic nature of solar urticaria. On the basis of experimental findings in the literature and our own observations, a new concept of the pathogenesis and classification of solar urticaria is presented. We propose two types of solar urticaria: type I, IgE-mediated hypersensitivity to specific photoallergens, which are generated only in patients with solar urticaria, and type II, induction of IgE-mediated hypersensitivity to a nonspecific photoallergen, which is generated both in patients with solar urticaria and in normal persons.

Humans↗
PubMed1989

Localized cicatricial pemphigoid (Brunsting-Perry): electron microscopic study.

Electron microscopic findings are presented in a patient with localized cicatricial pemphigoid (Brunsting-Perry). These findings revealed subepidermal separation below the basal lamina. The basal lamina and anchoring fibrils were well preserved and attached to the intact epidermis to form the roof of the blister. These findings support the concept that localized cicatricial pemphigoid, cicatricial pemphigoid, and disseminated cicatricial pemphigoid are closely related diseases and may explain the occurrence of scar formation in localized cicatricial pemphigoid. A review of 42 cases reported in the world literature is included, with emphasis on clinical, histologic, and immunofluorescence microscopic findings.

Aged↗
PubMed1988

Solar urticaria induced by visible light and inhibited by UVA.

A 17-year-old male with solar urticaria is described. The action spectrum ranged from 400 to 520 nm. Wheals induced by visible light were inhibited by simultaneous or subsequent irradiation of the skin with UVA radiation. UVA irradiation prior to exposure to eliciting wavelengths revealed no inhibitory effect, nor was an inhibitory effect found by pre- or postirradiation of test sites with visible light longer than 530 nm. In vitro activation of the patient's serum by exposure to visible light induced wheal formation at the injection site. The wheal formed by in vitro-activated serum was suppressed only when the serum was exposed to UVA after, but not before irradiation with wavelengths of the action spectrum. This suggests that the inactivation of a photoallergen rather than of its precursor is the mechanism by which UVA exerts an inhibitory effect.

Adolescent↗
PubMedDate not supplied

Relationship between skin color and cutaneous response to ultraviolet radiation in Thai.

Predictors of sensitivity to ultraviolet (UV) light, including Fitzpatrick's sun reactive skin types, constitutive skin color and facultative skin color were assessed in 43 healthy Thai volunteers. These predictors were compared with one another and with responses of the skin to UV irradiation, as determined by a minimal erythema dose (MED) of UVB, a minimal immediate pigment darkening dose (MIPDD) of UVA, and a minimal delayed tanning dose (MDTD) of UVA, and by dose-response curves for erythema and pigmentation, as measured objectively with the use of a narrow-band spectrophotometer. The skin type did not correspond well to the constitutive and facultative skin color. There was no correlation between skin type and MED and no relation between skin type and the slope of the dose-response curves for erythema and pigmentation. Constitutional skin color was also not a good predictor of the measured MED, MIPDD and MDTD values but did appear to correlate with the steepness of the dose-response curves for erythema but not for pigmentation. The facultative skin color, however, did not correlate with the dose-response angle of erythema or pigmentation. We have thus found that the skin type is not a good predictor of UV responses in Thai. The constitutive skin color is a better predictor of UV responses of the skin than skin type and that steepness of dose-response curves for erythema is a better measure of the response of the skin to UV irradiation than is a MED measurement.

Adolescent↗
PubMedDate not supplied

A comparison of erythema efficacy of ultraviolet B irradiation from Philips TL12 and TL01 lamps.

The erythema efficacy of UVB irradiation from Philips TL12 and TL01 lamps has been evaluated and compared. Thirty-seven healthy Thai volunteers were irradiated on the previously unexposed lower back with TL12 and TL01 lamps in doses ranging 100 to 550 mJ/cm2 and 360 to 2020 mJ/cm2, respectively. Erythema was evaluated clinically and measured by a narrow-band spectrophotometer before exposure and 24 h after exposure. The threshold doses of UVB that induced barely perceptible erythema (MEDb) with well-defined border erythema (MEDw) and the steepness of the dose-response curves for erythema (DRAE) were compared. We found that MEDb and MEDw of the TL01 lamps were 4.19 and 4.52 times those of TL12 lamps, which were similar to those calculated from the CIE erythema action spectrum (4.2). However, the DRAE of the two lamps were quite similar. Because the initial dosage of UVB phototherapy is usually given as a percentage of a patient's MED, the initial exposure of TL01-UVB phototherapy should be about 4.2 times that of TL12-UVB.

Adolescent↗