Safe, mild ultraviolet-B exposure: An essential human requirement for vitamin D and other vital bodily parameter adequacy: A review.

The enigma of skin sunburning, skin ageing and skin cancer and essential vitamin D production both resulting from solar ultraviolet-B (280-315 nm) (UVB) exposure has long puzzled photobiologists. Advice to patients by non-photobiological clinicians is now often to sunbathe to acquire vitamin D adequacy. However, modern work shows only mild UVB exposure is needed to maintain satisfactory levels, which have been demonstrated as very similar in summer and winter from about 25° to 70° north. Even very careful high protection factor 15 sunscreen use does not prevent adequate production, although it is slightly reduced, such that obsessive use of very protective screens of 50 + might. Dark skin pigmentation too usually at most minimally impairs production. However, confinement indoors and widespread clothing cover can, but oral supplementation overcomes any such deficiency. Thus, vitamin D adequacy needs just mild regular UVB skin exposure well under sunburning levels, unlikely to cause significant skin damage. This suggests mild UVB exposure may also be needed for other bodily requirements, which is indeed so. Thus, it also prevents the development of contact dermatitis and polymorphic light eruption through suppressing adaptive immunity. It also prevents the occurrence of multiple skin infections resulting from this suppression through stimulating innate immunity and cutaneous bacterial defensin production. Finally, blood pressure is reduced through low-dose UVB-induced production of the vasodilator nitric oxide (though UVA, 315-400 nm, is more efficient). Thus, mild UVB exposure is important for several aspects of internal health, whereas high-dose exposure is extremely detrimental to cutaneous health.

Clustering mechanism of ethanol-water mixtures investigated with photothermal microfluidic cantilever deflection spectroscopy.

The infrared-active (IR) vibrational mode of ethanol (EtOH) associated with the asymmetrical stretching of the C-C-O bond in pico-liter volumes of EtOH-water binary mixtures is calorimetrically measured using photothermal microfluidic cantilever deflection spectroscopy (PMCDS). IR absorption by the confined liquid results in wavelength dependent cantilever deflections, thus providing a complementary response to IR absorption revealing a complex dipole moment dependence on mixture concentration. Solvent-induced blue shifts of the C-C-O asymmetric vibrational stretch for both anti and gauche conformers of EtOH were precisely monitored for EtOH concentrations ranging from 20-100% w/w. Variations in IR absorption peak maxima show an inverse dependence on induced EtOH dipole moment (µ) and is attributed to the complex clustering mechanism of EtOH-water mixtures.

Hallauer's Tusón: a decade of selection for tropical-to-temperate phenological adaptation in maize.

Crop species exhibit an astounding capacity for environmental adaptation, but genetic bottlenecks resulting from intense selection for adaptation and productivity can lead to a genetically vulnerable crop. Improving the genetic resiliency of temperate maize depends upon the use of tropical germplasm, which harbors a rich source of natural allelic diversity. Here, the adaptation process was studied in a tropical maize population subjected to 10 recurrent generations of directional selection for early flowering in a single temperate environment in Iowa, USA. We evaluated the response to this selection across a geographical range spanning from 43.05° (WI) to 18.00° (PR) latitude. The capacity for an all-tropical maize population to become adapted to a temperate environment was revealed in a marked fashion: on average, families from generation 10 flowered 20 days earlier than families in generation 0, with a nine-day separation between the latest generation 10 family and the earliest generation 0 family. Results suggest that adaptation was primarily due to selection on genetic main effects tailored to temperature-dependent plasticity in flowering time. Genotype-by-environment interactions represented a relatively small component of the phenotypic variation in flowering time, but were sufficient to produce a signature of localized adaptation that radiated latitudinally, in partial association with daylength and temperature, from the original location of selection. Furthermore, the original population exhibited a maladaptive syndrome including excessive ear and plant heights along with later flowering; this was reduced in frequency by selection for flowering time.

The science of dermocosmetics and its role in dermatology.

Our increased knowledge of normal skin physiology has ushered in a subtle revolution in cosmetic science. Originally designed as preparations to enhance personal appearance by direct application on to the skin, cosmetics have now taken on a new role in dermatology, through the support of the management of many skin disorders. This evolving role of cosmetics in skin care is primarily due to scientific and technological advancements that have changed our understanding of normal skin physiology and how cosmetics modify its appearance both physically and biologically. The vast array of techniques currently available to investigate skin responsivity to multiple stimuli has brought about a new era in cosmetic and dermocosmetic development based on a robust understanding of skin physiology and its varied responses to commonly encountered environmental insults. Most cosmetic research is undertaken on reconstructed skin models crucial in dermatological research, given the strict ban imposed by the European Union on animal testing. In addition, the design and conduct of trials evaluating cosmetics now follow rules comparable to those used in the development and evaluation of pharmaceutical products. Cosmetic research should now aim to ensure all trials adhere to strictly reproducible and scientifically sound methodologies. The objective of this review is to provide an overview of the multidisciplinary scientific approach used in formulating dermocosmetics, and to examine the major advances in dermocosmetic development and assessment, the safety and regulatory guidelines governing their production and the exciting future outlook for these dermocosmetic processes following good practice rules.

Phase stability and elastic properties of Cr-V alloys.

V is the only element in the periodic table that forms a complete solid solution with Cr and thus is particularly important in alloying strategy to ductilize Cr. This study combines first-principles density functional theory calculations and experiments to investigate the phase stability and elastic properties of Cr-V binary alloys. The cluster expansion study reveals the formation of various ordered compounds at low temperatures that were not previously known. These compounds become unstable due to the configurational entropy of bcc solid solution as the temperature is increased. The elastic constants of ordered and disordered compounds are calculated at both T = 0 K and finite temperatures. The overall trends in elastic properties are in agreement with measurements using the resonant ultrasound spectroscopy method. The calculations predict that addition of V to Cr decreases both the bulk modulus and the shear modulus, and enhances the Poisson's ratio, in agreement with experiments. Decrease in the bulk modulus is correlated to decrease in the valence electron density and increase in the lattice constant. An enhanced Poisson's ratio for bcc Cr-V alloys (compared to pure Cr) is associated with an increased density of states at the Fermi level. Furthermore, the difference charge density in the bonding region in the (110) slip plane is highest for pure Cr and decreases gradually as V is added. The present calculation also predicts a negative Cauchy pressure for pure Cr, and it becomes positive upon alloying with V. The intrinsic ductilizing effect from V may contribute, at least partially, to the experimentally observed ductilizing phenomenon in the literature.

Case report of four patients with erythrodermic cutaneous T-cell lymphoma and severe photosensitivity mimicking chronic actinic dermatitis.

The marked photosensitivity associated with chronic actinic dermatitis (CAD) is presumed to be due to a T cell-mediated response to ultraviolet (UV)-induced epidermal neoantigens. Photosensitivity is, however, a rare occurrence in cutaneous T-cell lymphoma (CTCL). We discuss a series of four patients with erythrodermic CTCL who exhibited marked photosensitivity mimicking CAD. Significantly, the tumour cells had a CD8 phenotype in half of these patients. All patients had T-cell clones in skin and also demonstrated identical peripheral T-cell clones in blood or lymph node involvement. Sézary cell counts ranged from 6% to 20%, CD4/CD8 ratios from 0.22 to 23.5. Clinical presentation was striking for a marked photosensitive distribution. Monochromator irradiation testing revealed reduced minimal erythema doses throughout UVB and UVA ranges, findings consistent with those seen in CAD. All patients subsequently died from systemic disease. These findings suggest that, rarely, malignant clonal T-cell populations may recognize a unique UV-induced neoantigen, resulting in the clinical features of severe photosensitivity mimicking those seen in CAD.

The quality of life of 790 patients with photodermatoses.

BACKGROUND: Polymorphic light eruption and erythropoietic protoporphyria (EPP) have been demonstrated to have a moderate and large impact on the quality of life (QoL) of patients, respectively. However, there is little information available about the impact of other photodermatoses on QoL. OBJECTIVES: To assess and compare the impact of all forms of photodermatoses on patients' QoL using the standard 1-week Dermatology Life Quality Index (DLQI) questionnaire and a modified questionnaire to assess the impact over the previous year. METHODS: All patients with photodermatoses seen between 2001 and 2005 at five U.K. photobiology centres were contacted by post on the same day during a forecasted sunny week across the U.K. and asked to complete DLQI questionnaires. RESULTS: A total of 1877 patients were contacted. Seven hundred and ninety-seven (42%) patients replied, with a range from 30% to 48% for the five individual centres. Nearly two-thirds of patients with actinic prurigo (AP) and more than one-third of patients with photoaggravated dermatoses (PAD), chronic actinic dermatitis, EPP and solar urticaria had a DLQI of > 10, confirming a very large effect of the disorders on QoL. Of the cutaneous porphyrias, both variegate porphyria (median DLQI 3) and porphyria cutanea tarda (median DLQI 1.5) had a much lower impact on QoL than EPP. CONCLUSION: This is the first large-scale study to attempt to measure the impact of a range of photodermatoses on QoL. Photodermatoses have a major impact on QoL. This impact is highest in AP and PAD.

Review of the potential photo-cocarcinogenicity of topical calcineurin inhibitors: position statement of the European Dermatology Forum.

Topical Calcineurin Inhibitors (TCIs) used for the treatment of atopic eczema modify the immune regulatory function of the skin and may have the potential to enhance immunosuppressive ultraviolet (UV) effects. Current recommendations on UV protection in eczema patients treated with PCIs are inconsistent and have given rise to uncertainty and anxiety in patients. Therefore, the European Dermatology Forum (EDF) developed a position statement which reviews critically the available data with regard to the problem, especially analysing and commenting the limitations of rodent models for the human situation. There is no conclusive evidence from rodent trials to indicate that long-term application of TCIs is photococarcinogenic. There is a need for further studies to investigate the validity of mouse models as well as long-term cohort studies in patients using TCIs. Available data suggest that long-term application of TCIs is safe, that there is no evidence of increased skin cancer risk and that it is ethical to treat patients with TCIs when indicated.

Persistent severe amiodarone-induced photosensitivity.

Amiodarone, a benzofuran derivative, has been used therapeutically as an antiarrhythmic and coronary vasodilator in Europe since 1964. One of its commoner side effects is cutaneous photosensitivity; more rarely, after ingestion of the drug for around 12 months, a slate-grey or violaceous discoloration of sun-exposed sites may gradually develop. Both of these side effects usually resolve within 2 years of discontinuation of the drug. We now present a woman who developed both photosensitivity and a slate-grey discoloration whilst taking amiodarone; on discontinuation of the drug, the dyspigmentation gradually resolved, but the photosensitivity has persisted and the patient remains symptomatic more than 17 years later.

Audit of the use of psoralen photochemotherapy (PUVA) and narrowband UVB phototherapy in the treatment of psoriasis.

BACKGROUND: Psoralen photochemotherapy (PUVA), the combined use of psoralen and long wave ultraviolet (UVA) irradiation, was introduced around 1974 and its beneficial effects were rapidly confirmed worldwide. In an attempt to minimize its recognized long-term photocarcinogenic risk after some 150-200 exposures while also maintaining efficacy, however, the narrowband (311-312 nm) ultraviolet B (UVB) lamp (TL-01) was introduced in 1984, and has moved towards replacing PUVA except for severe or resistant disease. AIMS: To discover whether our use of these therapies complied with established British Photodermatology Group guidelines for PUVA and guidelines formulated within our unit for narrowband UVB. METHODS: The study was retrospective over 6 months from November 2001 to April 2002, all relevant information being obtained from the patients' hospital notes. RESULTS: Thirty-one patients received PUVA (18 oral, 11 bath and two uncertain because of missing notes) and 20 narrowband UVB during this period. CONCLUSIONS: Our PUVA and narrowband UVB phototherapy guidelines were shown to have been followed relatively closely with the following exceptions: one PUVA patient received a high cumulative exposure by mutual agreement because there was no other suitable therapy; a failure to measure minimal phototoxic doses (MPDs) in some PUVA patients; and slightly prolonged referral delays, but generally by patient choice.

Exacerbation of presumed chronic actinic dermatitis by cockpit visible light in an airline pilot with atopic eczema.

Chronic actinic dermatitis (CAD) is a persistent ultraviolet radiation- or visible light-induced eczema of predominantly the exposed areas of usually elderly people. We now present the case of a young pilot with atopic eczema who developed CAD, regularly exacerbated by exposure to visible light through his aircraft cockpit window.

Erythema multiforme following polymorphic light eruption: a report of two cases.

We report two patients in whom episodes of polymorphic light eruption were followed by recurrent erythema multiforme on exposed and nonexposed sites. Treating the polymorphic light eruption with prophylactic PUVA and/or oral prednisolone or cyclosporin prevented the development of erythema multiforme, suggesting that the two events are related. It is possible that erythema multiforme develops as a response to the same causative antigen as polymorphic light eruption.

Rates of Seed Treatment Insecticides and Control of Stewart's Wilt in Sweet Corn.

Neonicotinoid insecticides applied as seed treatments reduce the incidence of Stewart's wilt. The objectives of this study were to examine the efficacy of different rates of seed treatment insecticides to control Stewart's wilt on susceptible sweet corn hybrids and to compare the economic value of Stewart's wilt control in sweet corn grown for processing and fresh market. Clothianidin (Poncho), imidacloprid (Gaucho), and thiamethoxam (Cruiser) applied to seed at rates ranging from 0.125 to 1.25 mg a.i. per kernel were evaluated in 11 field trials in Illinois and Delaware from 2000 to 2003. Incidence of Stewart's wilt was significantly lower when seed was treated with insecticides than when plants were grown from nontreated seed in all but one trial. The level of control usually was between 50 and 90%. Small but statistically significant differences in incidence of systemically infected plants occurred among rates of insecticides in all trials except those in 2001. Usually, incidence of systemic Stewart's wilt was lower when higher rates of insecticides were applied; however, increasing the rate of insecticides from 0.125 mg a.i. to 1.25 mg a.i. per kernel had a relatively small effect on the level of Stewart's wilt control compared with the difference between treated and nontreated sweet corn seed. Based on a regression analysis, the lowest rates of the insecticides provided 64 to 72% control. The level of control increased about 1.85% with each additional 0.1 mg a.i. of insecticide per kernel from 0.125 mg a.i. to 1.25 mg a.i. Clothianidin provided an 8 or 9% higher level of control than thiamethoxam or imidacloprid at the same rate. Recommendations for application of seed treatment insecticides to processing and fresh market sweet corn differed somewhat due to substantial differences in the value of the crops. Based on estimated costs of $6 to $12 per 0.4 ha for the seed treatments, the economic break even point (i.e., cost of control = value from control) occurred in the range of 3 to 6% Stewart's wilt incidence for processing sweet corn valued at $325 per 0.4 ha and at about 1% Stewart's wilt incidence for fresh market sweet corn valued at $1,625 per 0.4 ha. Relatively small differences in levels of control conferred by commercially available rates of clothianidin (0.25 mg a.i. per kernel) and thiamethoxam (0.125 mg a.i. per kernel) were of little consequence in processing sweet corn but had considerable economic value in fresh market sweet corn.

Glaucoma induced by periorbital topical steroid use--a rare complication.

Eye complications arising during systemic and ophthalmic steroid use are well known. In contrast, there is little highlighting the similar risks associated with topical steroid use around the eyelids. We now describe a 29-year-old lady who used topical steroids in prolonged fashion throughout most of her life for severe eczema, with the recent application of large quantities of potent steroid continuously for one month, including to the periorbital region. Soon after, she presented to her ophthalmologist with severe bilateral glaucoma and irreversible visual loss attributed to the steroid use. Here we emphasise the possible risks of periorbital topical steroid use, as well as the importance of patient education and ophthalmological follow-up.