Examination of the itch response from the raphides of the fishtail palm Caryota mitis

Study of two plants used in traditional medicine in Zimbabwe for skin problems and rheumatism: Dioscorea sylvatica and Urginea altissima

Two plants used in Zimbabwean traditional medicine, Dioscorea sylvatica (Dioscoreaceae) and Urginea altissima (Liliaceae), produce mild inflammation and itching when rubbed on the skin. Investigations of the causes of these cutaneous reactions showed that raphides of calcium oxalate are, at least in part, responsible for the effects. Histamine could not be detected.

Irritant contact dermatitis caused by needle-like calcium oxalate crystals, raphides, in Agave tequilana among workers in tequila distilleries and agave plantations

It was found that needle-like calcium oxalate crystals, raphides, are found abundantly in all tissues of Agave tequilana plants; thus, 1 droplet (0.03 ml) of juice pressed from leaves contains 100-150 crystals, 30-500 microm in length, sharpened at both ends. In tequila distilleries, 5/6 of the workers who handle the agave stems have experienced the characteristic irritation. In contrast, only 1/3 of workers in agave plantations who harvest agave plants, complain of the irritation. It is confirmed that all the irritation suffered in both distilleries and plantations takes place at bodily locations where the plants come into contact with the worker's skin in the course of their work.

Vulvar pain syndrome: a review

Vulvar pain syndrome (vulvar vestibulitis, vulvodynia, burning vulvar syndrome) was first described at the end of the last century. Although more than 100 years have passed, the cause(s) of the disorder remains elusive. This review of the literature endeavors to collate the known facts relating to vulvar pain syndrome and to expose those hypothetical etiologies which fall short of establishing any scientific foundation. The diagnosis of vulvar pain syndrome is established on the basis of historical data which detail a rather abrupt onset of vestibular itching, burning, dryness which may be intermittent or continuous. Commonly, patients present with a history of chronic treatment for recurrent fungal infections. Sexual relations become uncomfortable or intolerable. Unanimously, the patients describe a panorama of topical creams and ointments which fail to alleviate the symptoms. Physical examination typically verifies hyperesthesia of the vestibular skin when touched lightly with a cotton-tipped applicator. Similarly, the vestibular skin shows varying degrees of redness. The treatment programs for vulvar pain syndrome are as diverse as the multitude of etiological hypotheses. This review includes data pointing out those therapeutic measures that appear valueless and that may add to the patient's chronic discomfort.

Observations on the idioblasts of Dieffenbachia

The toxicity of the Arum genus, especially the Dieffenbachia, has long been a topic of controversy. Some believe that the injury inflicted is primarily mechanical, the result of needle like crystals of calcium oxalate (raphides) found in the stems and leaves. Others cite evidence supporting the existence of enzymatic and allergic injury. This paper describes a hitherto neglected third factor, specialized cells which can forcibly shoot the raphides and which may be necessary for the toxic effect since raphide containing plants devoid of these cells are not toxic. The effects of physical and chemical factors on the behavior of these cells are described.

The dermatitic properties of black bryony (Tamus communis L.)

The skin irritant properties of both the juice expressed from the ripe berries and the slimy mucilage present in the rhizomes of black bryony (Tamus communis L.) were investigated. The dermatitis produced on human skin after gently rubbing in either the berry juice or the rhizome mucilage was found in both cases to be a result of mechanical irritation, being produced by penetration of the skin by minute needle-like crystals of calcium oxalate. Scanning electron micrographs supporting this conclusion are presented. Chemical investigation of the rhizome mucilage confirmed the presence of histamine. The rôle of histamine in the production of skin irritation following contact with the rhizome mucilage is discussed.