Fixation-off (Scoto) sensitivity combined with photosensitivity

A 16-year-old boy of normal intelligence had brief absence and myoclonic jerks since age 7 years. Video-EEG documented the unexpected combination of fixation-off sensitivity (scotosensitivity) with photosensitivity.     

Protection against photodynamic therapy (PDT)-induced photosensitivity by fabric materials

"Special" highly protective fabrics are now available that offer broad-spectrum protection in preventing sunburn, and possibly other types of photodamage. It is important to know to what extent these fabrics are capable of protecting the wearer against skin cancer, photosensitivity disorders, and inadvertent phototoxic reactions from photodynamic therapy (PDT). We assess the ability of one such special (Solumbra) fabric and one "typical" summer fabric to provide protection against PDT phototoxicity produced in tape-stripped Sk-1 hairless mice by topical 5-aminolevulinic acid (ALA) and (primarily) visible light (360-800 nm). Since ALA-derived photosensitizers absorb most of the visible spectrum, results from these studies give a good indication of the photoprotective capability of these fabrics throughout this region. Mice were irradiated dorsally with a Kodak slide projector equipped with a 300 W tungsten-halogen lamp (I0 = 48.3 mW/cm2). After determining the minimal phototoxic dose (MPD) to be 1.40 +/- 0.4 J/cm2, we irradiated the tape-stripped ALA-sensitized mice through the stretched test fabrics with appropriate multiples of the MPD. The special fabric provided protection against 25-30 MPD visible light between 360-800 nm in 14/14 mice. The typical fabric failed to provide protection against 2.5 MPD of the same spectrum. No phototoxic or other adverse responses were seen with either the ALA or light control. In conclusion, the Solumbra fabric is much more protective against ALA photosensitization than the typical fabric. Both appear better at blocking UV than visible light.     

Principles and technicals studies of investigating photosensitivity of the skin (author's transl)

The authors report the principles of investigating photosensitivity of the skin: objects of testing and some basic practical consideration (doses, laws of irradiance, choice of wavelength in a test). Artificial sources for irradiation are studied. Xenon arc lamp is the most suitable. Two main kinds of device are suitable for routine radiant energy measurement; the thermopile with linear spectral response and the photoelectric cells without linear relationship between wavelength and sensitivity. To delimit the emission of xenon arc, the authors use absorption filters (cut-off type). Irradiation monochromator is indispensable to much dermatological photobiology, especially action spectrum study. Methods of measurement, time course of the response dose response relationship, threshold response and action spectrum of normal and abnormal effects of light on the skin are described. Routine phototesting procedure enclose: minimal erythemal dose, phototest, photopatchtest. Technical study and interpretation are exposed. For the dermatologist, phototesting procedure is necessary for the diagnosis. Mechanism of photosensitivity (phototoxic or photoallergic reaction) and wavelength dependence have to be known for an appropriate treatment.     

The photosensitivity dermatitis and actinic reticuloid syndrome (chronic actinic dermatitis) occurring in seven young atopic dermatitis patients

This study describes the translocation of the brain specific protein kinase C gamma isoenzyme (PKCgamma) in the hippocampus during food rewarded spatial learning. The holeboard test was used for spatial orientation, and immunoblot analysis was used for assessment of PKCgamma in cytosolic, membrane-inserted and membrane-associated fractions. Membrane-associated PKCgamma was increased during early acquisition of spatial learning, but not in a later phase of training. This transient and apparently temporary intracellular PKCgamma translocation was only observed in the posterior but not in the anterior hippocampus, and was only detected within 10 min after termination of the learning trial. This study supports the idea that PKCgamma is significantly involved in the biochemical events underlying learning and memory, notably during the period of novel information processing. The results further promote the hypothesis that the hippocampus is specifically involved in temporal information processing, which requires the engagement of PKCgamma.     

In vitro studies on the protoporphyrin uptake and photosensitivity of normal skin fibroblasts and fibroblasts from patients with erythropoietic protoporphyria

Fibroblasts derived from patients with erythropoietic protoporphyria (EPP) are not sensitive to violet light and do not contain an excess of protoporphyrin (PP). Fibroblasts from both normal individuals and patients with EPP can take up very low concentrations of PP from culture medium. Cells grown in PP-containing medium showed a gradually increasing but limited uptake of PP and also an increased sensitivity to light. A sensitive scanning microfluorometric method has made it possible to demonstrate that the PP is mainly localized in the perinuclear granules. After exposure to violet light, cells photosensitized by PP in a culture medium showed increased membrane permeability as well as reduced reproductive capacity. Both of these photodamage effects can be repaired during postirradiation incubation in culture medium at 37 degrees C.     

Inhibitory effect of melanin pigment on sensitization and elicitation of murine contact photosensitivity: mechanism of low responsiveness in C57BL/10 background mice

We have shown that murine contact photosensitivity (CPS) to 3,3',4',5-tetrachlorosalicylanilide (TCSA) is genetically controlled mainly by the major histocompatibility complex. The H-2b,d haplotypes are closely associated with high responders, whereas mice with the H-2k are non-responders. Irrespective of their H-2 haplotypes, the C57BL/10 (B10) background strains, including B10, B10.D2, B10.A, and B10.BR, possessing black fur color, were low or nonresponders in CPS to TCSA. In B10 mice, however, high-sensitivity responses were induced when subcutaneous inoculation of epidermal cells (ECs) photomodified in vitro with TCSA was used for both immunization and challenge, suggesting that the epicutaneous route for induction and elicitation is defective in B10 background mice. F1 mice obtained by crossing high-responder BALB/c and low-responder B10 mice, possessing agouti fur color, were non-responders of CPS. The magnitude of CPS in the F2 mice derived from F1 (BALB/c X B10) siblings varied from low to high. When these F2 mice were divided into five groups with regard to fur color, the magnitude of reaction was correlated with the fur color and there was inverse relationship between the magnitude of CPS and the amount of melanin pigment in earlobe ECs. Furthermore, the in vivo formation of TCSA-EC photoadducts was negatively correlated to the melanin amount in earlobes. These observations suggested that the failure in CPS of the B10 background mice stems from inability of in vivo photocoupling of TCSA to ECs, presumably due to absorption of ultraviolet radiation by melanin pigment.