T.M. Macleod

THE STUDY OF THE EFFICACY OF SOME AGENTS USED FOR THE PROTECTION OF THE SKIN FROM EXPOSURE TO LIGHT

—Mexenone. Red Veterinary Petrolatum, benzyl salicylate and benzyl cinnaniate, para-aminobenzoic acid, and (Hhydrogyacetone (DHA)/ Lawsone, were studied by in vitro and in vivo methods in a group of normal subjects and in patients suffering from polymorphic light eruption, solar urticaria, porphyria, or xeroderma pigmentosum. It was found that a preparation with an apparent adequate protection factor in normal subjects not infrequently failed to give comparable protection in patients with abnormal skin responses either on phototesting or in clinical use. A combined chemical and physical light protective preparation (Cream ERl) was therefore formulated and shown to be more effective. The difficulty in prescribing light screening preparations without specific knowledge of the responsible wavebands is discussed, and attention is drawn to the frequent unreliability of in vitro studies as a means of determining the in vivo efficacy of a preparation.

New sunscreens confer improved protection for photosensitive patients in the blue light region

Background Some patients with photosensitivity disorders are sensitive to visible radiation. As current commercial sunscreens do not significantly absorb in this region, there is a lack of effective topical photoprotection. To meet this need a new range of sunscreens has been developed incorporating zinc oxide and pigmentary grade titanium dioxide as active ingredients.

The uptake of labelled thymidine by leucocytes of nickel sensitive patients.

SUMMARY.— Thymidine uptake studies using a predominantly lymphocyte suspension of white blood cells in a series of 12 cases of nickel contact dermatitis and 14 controls are reported.

A study of chemical light screening agents

In those photodermatoses in which the action spectrum involves wavelengths outside the short ultraviolet (i.e. >320 nm) little protection can be obtained against long UV (>320 nm) by the application of chemical light screening agents. An action spectrum involving wavelengths >320 nm is a common occurrence and may necessitate the additional provision of protection from a physical light screening agent. Such a physical agent is titanium dioxide and in a study of its use in a variety of formulations using in vitro techniques it was shown to be effective throughout the wavelengths 400‐700 nm. It was also shown to have a satisfactory protective capacity in those photodermatoses in which the action spectrum involves wavelength peaks 365 nm (335–395 nm) and 400 nm (370–430 nm). It also has a reasonable cosmetic acceptability provided care is taken to incorporate in the formulations colouring agents which can be varied to suit the individual patient.

THE INVESTIGATION OF PHOTOCONTACT DERMATITIS IN A DYE MANUFACTURING PROCESS

Summary.— An investigation of photocontact dermatitis occurring in a dye manufacturing process is described. Sixteen employees were studied by photopatch testing to the complete anthraquinone‐based dye: Disperse Blue 35 and to chromatographically separated bands. By irradiation of the skin with visible light between 400 and 700 nm evidence was obtained to show that the complete dye produced photo‐contact dermatitis in individuals, whether they had previously been exposed to it or not. Using the same technique, only 4 of the 10 constituent hands produced a similar photocontact reaction.

Nickel hypersensitivity. Nickel binding to amino acids and lymphocytes.

The nature of a protein hapten conjugate which could effect lymphocyte transformation in nickel hypersensitivity was investigated by subjecting the culture media employed to radiochromatographic analysis. Autoradiographic studies with 63Ni demonstrate direct binding of nickel salts to the lymphocyte cell surface. This occurs with a proportion of lymphocytes both from nickel sensitive and from control subjects and so binding is not of itself the stimulus for transformation.

In vitro lymphocyte studies in chronic polymorphic light eruption

Lymphocytes suspended in autologous sera from seven subjects with chronic polymorphic light eruption were irradiated with UV radiation corresponding to the peak of their action spectra, and lymphocyte transformation and migration inhibition studies were subsequently carried out. The results obtained do not support a concept of photoallergy, but an increased thymidine uptake ratio was obtained in one subject, the only one who had shown clinical involvement of covered skin sites in addition to light exposed ones.

The leukocyte migration inhibitión test in allergic nickel contact dermatitis

No statistical difference was found between the migration indices of nickel sensitive and control subjects using the leukocyte migration inhibition test with two concentrations of nickel sulphate. The results contrast with the specific positive results demonstrated previously in the same subjects with the lymphocyte transformatior test

Electrophoretic mobility of human lymphocytes — An investigation of the technique of cytopherometry

Abstract Cell surface charge has been investigated as a possible characteristic of lymphocyte sub-populations. Lymphocytes were separated from heparinised blood by a Ficoll-Triosil method and their electrophoretic mobility measured with a cytopherometer. The instrument used was found to have inherent faults which were eliminated by certain modifications. Ability thereafter to obtain reproducible results commends it as a useful tool in the study of lymphocytes in disease states. Investigation of 17 control subjects showed that two sub-populations with electrophoretic mobilities less than and greater than 1.01 × 10−4 cm2ν−1 sec−1 were identifiable in a ratio of approximately 75:25 with peaks at 1.15 and 0.95 × 10−4 cm2ν−1 sec−1 while in 5 subjects with chronic lymphocytic leukaemia the ratio was much less. In rats similar peaks were found at 1.22 and 0.90 × 10−4 cm2ν−1 sec−1 while in neo-natally thymectomised and irradiated rats the peak at 1.22 × 10−4 cm2ν−1 sec−1 was eliminated. These populations probably represent T and B cells. This investigative has considerable clinical applicability.

THE ADVANTAGES OF THE GLYCOGELATIN PATCH TEST OVER TRADITIONAL TESTING METHODS

SUMMARY.— The disadvantages of certain variable factors influencing the reliability of traditional patch test techniques have been discussed.