An analysis of plasma levels and 24-hour ECG recordings in tricyclic antidepressant poisoning: implications for management.

Twenty-seven patients with confirmed tricyclic antidepressant (TCA) self-poisoning were studied for 24 h following admission to hospital. Ten patients were judged to be severely poisoned on clinical grounds, whilst 14 patients had initial plasma levels above 1 mg l-1, indicating severe poisoning. Plasma levels were generally maximal on admission to hospital and fell quickly thereafter.

The erythemal response of human skin to ultraviolet radiation.

A reflectance instrument was used to measure objectively the erythemal response of human skin to ultraviolet radiation. Dose-response curves have been constructed for four radiation wavelengths. In each case, the measured increase in erythema was found to be linearly related to the logarithm of the dose of ultraviolet radiation.

An evaluation of sunscreens in patients with broad action-spectrum photosensitivity.

The photoprotection afforded by three sunscreens available by prescription in the U.K. has been studied in patients with severe broad action-spectrum photosensitivity.

Quantitative studies on cutaneous erythema induced by ultraviolet radiation.

A reflectance instrument was used to measure the variation in UVR-induced erythema at different positions on the back. The pre-irradiation erythema index decreased from top to bottom of the back but the increase in index remained constant for a fixed exposure dose. In contrast, the minimal erythema dose was higher at lower sites on the back.

A portable instrument for quantifying erythema induced by ultraviolet radiation.

The design and performance of an instrument for quantifying ultraviolet-induced cutaneous erythema are discussed. If the instrument is used to record an 'erythema index' at a site on the skin before and after irradiation, the difference between those two readings is essentially related to an increase in vasodilation and is largely independent of the melanin content of the epidermis.

A microcomputer program to predict sunburn exposure.

A simple microcomputer program written in BASIC calculates the time that can be spent in the sun without risk of sunburn. Seven data are requested by the computer: (1) the month, (2) the weather conditions, (3) the subject's complexion, (4) the subject's activity outdoors, (5) the sun protection factor if a sunscreen is used, (6) the latitude on the Earth's surface, and (7) the time of day at which sun exposure begins. The calculated "safe exposure time" is an estimate for the time to give a minimal erythema dose--a just visible sunburn.

Personal ultraviolet radiation dosimetry with polysulphone film badges.

The use of the plastic film, polysulphone, as a dosimeter for monitoring personal exposure to both natural and artificial sources of ultraviolet radiation is described. In particular, the relationship of the change in optical properties of the film with biologically-meaningful quantities, such as the minimal erythema dose, is explained.

A preliminary study on photoaddition and erythema due to UVB radiation.

The spectral irradiance of narrow band and broad spectrum radiation sources have been measured and the erythemally effective irradiance calculated by weighting the spectral irradiance of each source by an erythema action spectrum for human skin and integrating over the range of wavelengths in each spectrum. The ratio of the erythemally effective irradiances determined in this manner have been compared with the ratio of exposure times necessary to produce a delayed minimal perceptible erythema on the trunk skin of fair-skinned subjects irradiated with the two different sources. There was close agreement between the two ratios, supporting the notion of photoaddition applied to erythema elicited by UVB radiation.

A preliminary study on the in vivo transmission of light through psoriatic plaques.

The transmission of light through psoriatic plaques has been measured in vivo using a quartz fiber before and after the application of the lipophilic liquid, glycerin. The results indicated a roughly two-fold increase in transmission following the application of glycerin. This was achieved after a period which ranged from 3 to 15 min suggesting a diffusion process.

The establishment and clinical value of a dermatological photobiology service in a district general hospital.

The availability of a local dermatological photobiology facility has proved to be of great value in the management of patients with photodermatoses, especially those with chronic actinic dermatitis. It is our belief that clinically useful results can only be achieved if careful attention is paid to technical factors such as radiation measurement.

Using a microcomputer program to avoid sunburn.

A simple microcomputer program is described which is designed to calculate the time that can be spent in the sun without the risk of sunburn following the input of the seven variables listed below: Time of year (month); Weather; Subject's complexion; Subject's activity outdoors; Whether or not a sunscreen is being used; Subject's geographical latitude on the Earth's surface; Time of day at which sun exposure begins. The calculated 'safe exposure time' is, of course, not exact, but it will give a reasonable guide to follow.

Clinical climatology.

An appreciation of the influence of environmental factors regarding the quality and quantity of terrestrial ultraviolet radiation (UVR) is important when trying to optimize the conditions for climatic therapy of skin diseases or in order to minimize the harmful effects of the sun. The time of day, season of the year and geographical latitude all have strong influences on the amount of UVB energy reaching the surface of the Earth. For example, it is important to realize that there be may be more sunburning UVB around on a moderately cloudy day at midday than on a clear day in the late afternoon.

A direct comparison between subcutaneous and intralymphatic injections for lymphoscintigraphy.

Lymphoscintigraphy using 99mTc colloids has been proposed as a simple adjunct to lymphangiography. To validate the technique of subcutaneous injection we performed a direct comparison between intralymphatic and subcutaneous administration of 99mTc-antimony colloid. In all cases excellent correspondence was obtained between the two techniques.

A method for predicting the phototoxicity of non-steroidal anti-inflammatory drugs.

The photosensitisation potential of several non-steroidal anti-inflammatory drugs (NSAIDs) has been investigated in vivo using an irradiation monochromator. Evidence of abnormal, immediate photosensitivity was obtained in 13 of the 38 patients taking one of four out of seven different NSAIDs. A simple mathematical model was developed to predict the likelihood of photosensitivity occurring with a given drug by considering the mass of drug normally ingested, the spectral absorption characteristics of the drug, and the quantity and spectral quality of the radiation (e.