Radiation induced lichen planus - an uncommon side effect

Cutaneous lichen planus is classically characterized by violaceous, pruritic, planar papules and plaques, most commonly affecting the extremities. Lichen planus following radiation therapy is extremely rare and lichen planus following radiation therapy for prostate carcinoma has not been previously reported in the literature. We report a 66-year-old man who presented to the dermatology clinic with a symmetric pruritic eruption affecting the pelvic and gluteal region within two months of radiation therapy targeting the prostate and pelvic lymph nodes for prostate adenocarcinoma. The patient did not have a prior history of lichen planus. Physical examination demonstrated well demarcated, violaceous papules and plaques in a circumferential band-like distribution on the bilateral gluteal, lumbosacral, and pelvic region. In addition, he had a few discrete lesions on the calves and dorsal feet. Punch biopsy revealed an acanthotic epidermis with "saw-tooth" rete ridges and a lichenoid inflammatory infiltrate. A diagnosis of hypertrophic lichen planus was made, reinforcing the importance for clinicians to recognize radiation therapy as a risk factor for developing lichen planus despite no prior history of lichen planus

Phenolics, depsides and triterpenes from the chilean lichen pseudocyphellaria nudata (zahlbr.) D.J. Galloway

Indexación: ScieloThe lichen Pseudocyphellaria nudata is a species endemic to southern South América. From the lichen tallus, methyl orsellinate, 2-methoxy-3,6-dimethyl-4-hydroxybenzaldehyde, methyl-evernate, tenuiorin, hopan-6ß,22-diol and hopan-6α,76,22-triol were isolated and identified as the main lichen constituents. This is the first report of the occurrence of 2-methoxy-3,6-dimethyl-4-hydroxybenzaldehyde in lichens.http://www.scielo.cl/scielo.php?script=sci_arttext&pid=s0717-97072008000300017&nrm=is

A lichen protected by a super-hydrophobic and breathable structure

A species of lichen, Lecanora conizaeoides, is shown to be super-hydrophobic. It uses a combination of hydrophobic compounds and multi-layered roughness to shed water effectively. This is combined with gas channels to produce a biological analogue of a waterproof, breathable garment. The particular lichen grows mostly during wet seasons and is unusually resistant to acid rain [Hauck, M., 2003. The Bryotogist 106(2), 257-269; Honegger, R., 1998. Lichenologist 30(3),193-212]. The waterproof, breathable surface allows this lichen to photosynthesise when other species are covered with a layer of water. In addition, rainwater runs off the surface of the organism, reducing its intake of water from above and probably contributing to its resistance to acid rain

Lichens in Forest Park and Nitrogenous Air Pollution

Lichens have been shown to be useful bioindicators for determining levels of nitrogen deposition related to air pollution. Preliminary lichen surveys in Forest Park in 2011 and 2012 revealed the presence of lichen species associated with high levels of nitrogenous pollution. The summer of 2013, we conducted lichen surveys at 25 permanent research sites that had been set up in Forest Park and the Ancient Forest Preserve in 1993. The majority of the lichens we collected at every site were classified as indicative of worst, poor, or fair air quality, with few lichens found that would indicate good or best air quality. Lobaria is a lichen common in Oregon and is important in the normal nitrogen cycle in forests. However, Lobaria is very sensitive to nitrogenous air pollution and is associated with the best air quality category. We only collected Lobaria at one site in the middle of the park. We found no significant differences in lichens in the different air quality variables in the various sections of the park, indicating that all of Forest Park is subjected to poor air quality

Mediterranean lichens in the tropics : lichens of the mist oasis of Erkwit, Sudan

From the mist oasis of Erkwit (Red Sea coastal plain of Sudan) 25 epiphytic lichen taxa are reported, probably the first lichen floristic report for the country. Most species encountered are widespread in warm and dry areas worldwide, while a few have their center in the Mediterranean region and document a Mediterranean element in this tropical region

Influence of Cladonia substellata Vainio extracts and usnic acid on germination and growth of Allium cepa L. seedlings

The effect of lichen extracts obtained from Cladonia substellata and its main constituent, on the germination and growth of onion (Allium cepa L.) seedlings was investigated. No significant inhibitory effect of the lichen extracts and usnic acid on germination was found, except of usnic acid at the concentration of 726.7 mM. Growth inhibition of the radicle and of the hypocotyl of the seedlings was found for the total extract and for usnic acid in concentrations of 290.6 mM and 726.7 mM

Estimating coextinction risks from epidemic tree death

At least 10% of the world's tree species are threatened with extinction and pathogens are increasingly implicated in tree threats. Coextinction and threats to affiliates as a consequence of the loss or decline of their host trees is a poorly understood phenomenon. Ash dieback is an emerging infectious disease causing severe dieback of common ash Fraxinus excelsior throughout Europe. We utilized available empirical data on affiliate epiphytic lichen diversity (174 species and 17,800 observations) among 20 ash dieback infected host tree populations of F. excelsior on the island Gotland in the Baltic Sea, Sweden. From this, we used structured scenario projections scaled with empirical data of ash dieback disease to generate probabilistic models for estimating local and regional lichen coextinction risks. Average coextinction probabilities (A - ) were 0.38 (95% CI 60.09) for lichens occurring on F. excelsior and 0.14 (95% CI 60.03) when considering lichen persistence on all tree species. A - was strongly linked to local disease incidence levels and generally increasing with lichen host specificity to F. excelsior and decreasing population size. Coextinctions reduced affiliate community viability, with significant local reductions in species richness and shifts in lichen species composition. Affiliates were projected to become locally extirpated before their hosts, illuminating the need to also consider host tree declines. Traditionally managed open wooded meadows had the highest incidence of ash dieback disease and significantly higher proportions of affiliate species projected to go extinct, compared with unmanaged closed forests and semi-open grazed sites. Most cothreatened species were not previously red-listed, which suggest that tree epidemics cause many unforeseen threats to species. Our analysis shows that epidemic tree deaths represent an insidious, mostly overlooked, threat to sessile affiliate communities in forested environments. Current conservation and management strategies must account for secondary extinctions associated with epidemic tree death

Influence of ground substrate on establishment of reindeer lichen after artificial dispersal

Methods to improve the recovery of reindeer lichen after soil disturbance or overgrazing are being sought for areas where reindeer are herded. The effects of four substrates – mineral soil, moss, twigs and pine bark – on the establishment of lichen fragments after total removal of the vegetation were thus studied in a middle-aged pine stand and a clear-cut, both located in a lichen-rich pine-heath. Cladina mitis fragments of two sizes were manually dispersed in 1 m2 quadrats and their movements from their respective dispersal points were registered after one year. The natural re-establishment of lichens in the quadrats was monitored over three years by using digital pictures. In the forest stand, no significant differences were detected in either the fragment movement or the lichen establishment between the different substrates, but the fragment size had positive effects on both parameters. In the clear-cut, the moss substrate was the most suitable not only for the artificially dispersed lichens to fasten to, but also for the natural settlement of lichens from the surrounding lichen mat. More lichen thalli fastened to the bark and twigs substrates than to the mineral soil, but the settlement of lichens from the surrounding was greater on bare mineral soil substrate. The results indicate that artificial dispersal of lichen thalli on an appropriate substrate could be a successful strategy for promoting lichen recovery

Topical Tocopherol for treatment of reticular oral lichen planus: randomized, double-blind, crossover study

This randomized, double-blind, placebo-controlled crossover study assessed the efficacy of topical tocopherol acetate compared with placebo in easing oral discomfort in patients with reticular oral lichen planus (ROLP)