Plant Dermatitis.

Plant dermatitis is a common pathology that plagues those who work and recreate in the North American outdoors. The most common plant family to cause dermatitis is the Toxicodendron genus, which includes the plants known by the common names of poison ivy, poison oak, and poison sumac. While mortality is usually quite low for this pathology, the incidence and prevalence of the disease leads to substantial healthcare burden and financial implications across the population. The mainstays of treatment have focused on prevention, corticosteroids, and antihistamines.

Recurrent erythema multiforme-like reaction secondary to recurrent poison ivy exposure.

A 14-year-old boy developed an erythema multiforme-like reaction following Toxicodendron radicans (poison ivy) allergic contact dermatitis three separate times over the course of 3 years. The severity of each erythema multiforme-like reaction corresponded to the severity of the allergic contact dermatitis which preceded it.

Evaluation and Management of Toxicodendron Dermatitis in the Emergency Department: A Review of Current Practices.

Toxicodendron dermatitis is an underappreciated disease seen in the emergency department. Although self-limiting, symptoms can be distressing and can last for weeks if untreated, particularly with re-exposure. Continuing research has improved our understanding of specific inflammatory markers that are associated with exposure to urushiol-the compound responsible for Toxicodendron dermatitis-although consensus for treatment remains varied and poorly supported. Owing to the lack of recent primary literature on the topic, many providers rely on historical precedent, expert opinion, and personal experience when treating this disease. This article provides a narrative review of the literature currently available on the effects of urushiol on key molecular and cellular functions and the prevention and treatment of Toxicodendron dermatitis.

Black-Spot Toxicodendron Dermatitis With Varied Presentation.

This article describes the clinical presentation, differential diagnosis, and treatment of 2 unrelated cases with different presentations of black-spot Toxicodendron dermatitis. In the first case, a healthy 7-y-old male presented with a rash consisting of black dots with localized surrounding erythema on the left arm. The rash then progressed to a vesicular, pinpoint, raised rash spreading to the face, arms, and neck. In the second case, a 4-y-old male presented with non-pruritic, black, flat, non-erythematous lesions that did not progress. This patient's older sibling had been diagnosed with poison ivy 1 wk prior, and they attended the same child care where the poison ivy was thought to be acquired. In both cases, diagnosis of black-spot Toxicodendron dermatitis was made. The black spot of Toxicodendron dermatitis is caused by urushiol oxidation on exposure to air. The subject may or may not go on to develop allergic contact dermatitis after the exposure. Diagnosis of this dermatitis is made on clinical presentation, with careful consideration of history, distribution, and lesion morphology. When allergic dermatitis does develop as in the first case, systemic treatment with oral steroids is recommended. In both of these cases the black dots completely resolved in 2 to 3 wk. Dermatologic referral for dermoscopy and biopsy may be necessary if the dermatosis does not resolve as anticipated.

Habitat Suitability and Establishment Limitations of a Problematic Liana.

The US native liana, poison ivy (Toxicodendron radicans), responsible for contact dermatitis in humans, is a competitive weed with great potential for expansion in disturbed habitats. To facilitate a better understanding of this threat, we sought to evaluate habitat suitability, population demography, and biotic interactions of poison ivy, using a series of complementary field studies in the two habitats where it most commonly occurs-forest interiors and edges. Of the 2500 seeds planted across both habitats, poison ivy initially colonized forest interiors (32% emergence) at a higher rate than edge habitats (16.5% emergence). However, forest interior seedlings were less likely to survive (interior n = 3; edge n = 15), which might be attributed to herbivore pressure when the seedlings were smaller in the less competitive forest interior. Once established, the poison ivy seedlings appeared to be more tolerant of herbivory, except that of large grazers such as deer. The early life stage of seedling emergence, survival, and establishment are critical in poison ivy success, with biotic pressure, especially from plant competition and deer, limiting recruitment. A suitable habitat of this expanding native liana would increase with increasing forest fragmentation, but might be buffered by the expanding deer population.

Toxicodendron Contact Dermatitis: A Case Report and Brief Review.

Contact dermatitis caused by the sap of plants from the Anacardiaceae family, including poison ivy, oak, and sumac, is among the most common skin conditions in the United States. The author reports the case of a 50-year-old man who presented with numerous vesicles and flaccid bullae on erythematous bases on his right volar wrist; smaller areas of vesiculation on his trunk and legs, several of which displayed a linear configuration; and erythema and swelling on and around his penis. The patient was diagnosed with Toxicodendron contact dermatitis caused by exposure to poison ivy. The author describes symptoms, assessment methods, and differential diagnoses, as well as provides a brief review of pathologic and etiologic factors, epidemiology, and treatment approaches for cutaneous dermatitis caused by contact with poison ivy and related plants. The author also provides an brief history, recommended therapies, and notable physical characteristics of poison ivy, with the final takeaway point-Clinicians should educate their patients on how to identify, and, thus, avoid, contact with these highly irritating plants.

The complete genome sequence of Toxicodendron radicans, Eastern Poison Ivy.

Eastern Poison Ivy ( Toxicodendron radicans, Anacardiaceae) is well known in Eastern North America for causing contact dermatitis, an itchy and painful rash in most people who come in contact with it.  We present the whole genome sequence and annotation of this species. A total of 96,255,779 paired-ends reads consisting of 28.9 G bases were obtained by sequencing one leaf from a wild-collected plant.  The reads were assembled by a de novo method followed by alignment to related species. Annotation was performed via GenMark-ES. The raw and assembled data is publicly available via GenBank: Sequence Read Archive ( SRR10325927) and Assembly ( GCA_009867345).

Accession-Level Differentiation of Urushiol Levels, and Identification of Cardanols in Nascent Emerged Poison Ivy Seedlings.

Poison ivy (Toxicodendron radicans (L.) Kuntze) shows accession-level differentiation in a variety of morphometric traits, suggesting local adaptation. To investigate whether the presumed defense compound urushiol also demonstrates accession-level accumulation differences, in vitro nascent germinated poison ivy seedlings from geographically isolated populations were germinated in vitro and then assayed for known urushiol congener accumulation levels. Significant accession-level differences in the accumulation levels of total C15- and C17-, total C15-, total C17-, specific C15 congeners, and specific C17 congeners of urushiol were identified. In addition, hereto novel C15- and C17-urushiol isomers were identified as well. Cardanols are assumed to be the penultimate metabolites giving rise to urushiols, but this assumption was not previously empirically validated. C15-cardanol congeners and isomers corresponding to expected substrates needed to produce the observed C15-urushiol congeners and isomers were identified in the same poison ivy seedling extracts. Total C15-cardanol and C15-cardanol congeners also showed significant accession-level differences. Based on the observed C15-cardanol congeners in poison ivy, the penultimate step in urushiol biosynthesis was proposed to be a cardanol-specific hydroxylase activity.

Sequencing and De Novo Assembly of the Toxicodendron radicans (Poison Ivy) Transcriptome.

Contact with poison ivy plants is widely dreaded because they produce a natural product called urushiol that is responsible for allergenic contact delayed-dermatitis symptoms lasting for weeks. For this reason, the catchphrase most associated with poison ivy is "leaves of three, let it be", which serves the purpose of both identification and an appeal for avoidance. Ironically, despite this notoriety, there is a dearth of specific knowledge about nearly all other aspects of poison ivy physiology and ecology. As a means of gaining a more molecular-oriented understanding of poison ivy physiology and ecology, Next Generation DNA sequencing technology was used to develop poison ivy root and leaf RNA-seq transcriptome resources. De novo assembled transcriptomes were analyzed to generate a core set of high quality expressed transcripts present in poison ivy tissue. The predicted protein sequences were evaluated for similarity to SwissProt homologs and InterProScan domains, as well as assigned both GO terms and KEGG annotations. Over 23,000 simple sequence repeats were identified in the transcriptome, and corresponding oligo nucleotide primer pairs were designed. A pan-transcriptome analysis of existing Anacardiaceae transcriptomes revealed conserved and unique transcripts among these species.

MALDI-MS Imaging of Urushiols in Poison Ivy Stem.

Urushiols are the allergenic components of Toxicodendron radicans (poison ivy) as well as other Toxicodendron species. They are alk-(en)-yl catechol derivatives with a 15- or 17-carbon side chain having different degrees of unsaturation. Although several methods have been developed for analysis of urushiols in plant tissues, the in situ localization of the different urushiol congeners has not been reported. Here, we report on the first analysis of urushiols in poison ivy stems by matrix-assisted laser desorption/ionization-mass spectrometry imaging (MALDI-MSI). Our results show that the urushiol congeners with 15-carbon side chains are mainly localized to the resin ducts, while those with 17-carbon side chains are widely distributed in cortex and vascular tissues. The presence of these urushiols in stem extracts of poison ivy seedlings was confirmed by GC-MS. These novel findings provide new insights into the spatial tissue distribution of urushiols that might be biosynthetically or functionally relevant.

Efficacy of the saponin component of Impatiens capensis Meerb.in preventing urushiol-induced contact dermatitis.

ETHNOPHARMACOLOGICAL RELEVANCE: Many different tribes of American Indians used jewelweed, Impatiens capensis Meerb, as a plant mash to reduce development of poison ivy dermatitis. Saponins are a natural soapy constituent found within plants. A 2012 study suggested that saponins may be present in jewelweed which could be responsible for its efficacy in preventing rash development following contact with Toxicodendron radicans (L.) Kuntze (poison ivy). This study validated this hypothesis and demonstrated additional biological activity of the jewelweed saponin containing extract. MATERIALS AND METHODS: Fresh I. capensis leaves were extracted with methanol and further partitioned between ethyl acetate and water, with a final separation between water and n-butanol, to obtain a saponin containing extract. The presence of saponins in the extract was demonstrated by the observation of foaming and using a vanillin colorimetric assay for total saponins. Efficacy of the saponin containing extracts in rash reduction was tested by brushing poison ivy (PI) onto the forearms of volunteers (N=23) in six locations and treating these PI exposed areas with distilled water (control), saponin containing extracts, fresh plant mashes, and soaps made with and without plant extracts. Saponin containing extracts were further tested for biological activity against both gram negative and gram positive bacteria and against cancer cell lines A-375, HT-29, and MCF-7. Additionally, because saponins have been shown to have a stimulatory effect in cardiac muscle 2 µl saponin extract was applied superficially to black worms, Lumbriculus variegatus (N=5). RESULTS, AND CONCLUSIONS: Both saponin containing extracts and all soaps tested were effective in reducing poison ivy dermatitis; thus, saponin content correlates with PI rash prevention. No apparent antibiosis was observed against any bacteria tested; however, dose response cytotoxicity was documented against MCF-7 breast cancer cells and cytostatic activity was seen against the HT-29 colon cancer cell lines. Lumbriculus variegatus exhibited a 138% increase in heart rate over baseline rate five minutes post treatment implying a possible positive chronotropic effect.

Treatment of severe poison ivy: a randomized, controlled trial of long versus short course oral prednisone.

BACKGROUND: Toxidendron (poison ivy, oak, and sumac) contact dermatitis is a common complaint in the outpatient primary care setting with little evidence-based guidance on best treatment duration. METHODS: This randomized, controlled trial examined the efficacy and side effects of a 5-day regimen of 40 mg oral prednisone daily (short course) compared to the same 5-day regimen followed by a prednisone taper of 30 mg daily for 2 days, 20 mg daily for 2 days, 10 mg daily for 2 days, and 5 mg daily for 4 days over a total of 15 days (long course) in patients with severe poison ivy dermatitis. RESULTS: In 49 patients with severe poison ivy, non-adherence rates, rash return, medication side effects, and time to improvement and complete healing of the rash were not significantly different between the two groups. Patients receiving the long course regimen were significantly less likely to utilize other medications (22.7% vs. 55.6%, P = 0.02, number needed to treat 3.05). CONCLUSIONS: This study suggests that a longer course prescription may save patients' time and exposure to excess medication in the treatment of severe poison ivy. Application of this information to clinical practice will save return visits and reduce excess non-prescription medication administration to individual patients.