Recognizing the Toxicodendrons (poison ivy, poison oak, and poison sumac).
Poison ivy, poison oak, and poison sumac are now classified in the genus Toxicodendron which is readily distinguished from Rhus. In the United States, there are two species of poison oak, Toxicodendron diversilobum (western poison oak) and Toxicodendron toxicarium (eastern poison oak). There are also two species of poison ivy, Toxicodendron rydbergii, a nonclimbing subshrub, and Toxicodendron radicans, which may be either a shrub or a climbing vine. There are nine subspecies of T. radicans, six of which are found in the United States. One species of poison sumac, Toxicodendron vernix, occurs in the United States. Distinguishing features of these plants and characteristics that separate Toxicodendron from Rhus are outlined in the text and illustrated in color plates.
Review of significant progress in clinical dermatology since 1977.
The disease rules all; the patient, except for HLA typing, is in eclipse. Immunology holds the key to new knowledge. Management lingers at present behind scientific advance (systemic lupus erythematosus), or is fired by a new, and possibly overenthusiastic, aggressive spirit (mycosis fungoides). Classification of clinical disease is bound to change (dermatitis herpetiformis). Our concept of Staphylococcus aureus has been widened further (toxic shock syndrome). Psoriasis, a more unpleasant disease than we have cared to admit, may be connected with a generalized enzyme defect. Psoriasis, acne, and other disorders of keratinization respond to newer oral retinoids. Some vignettes of new therapy, new toxicity, new ideas, and old ideas seen anew have been presented.
Human exposure to methylmercury from crayfish (Procambarus clarkii) in China
Methylmercury (MeHg) accumulation in aquatic food raises global concerns about human exposure to MeHg. Crayfish is the world’s third largest farmed crustacean species and a favorite aquatic food in many countries. However, human health hazard due to MeHg exposure via crayfish consumption is unclear, partly because appropriate survey data are lacking. We report on mercury concentrations and speciation in edible tail muscle of crayfish collected from restaurants in 23 Chinese cities. On average, MeHg constituted 99.1 % of mercury in tail muscle, and MeHg concentrations were comparable with those reported for fish in China. Variation in MeHg concentrations was not attributable to broad geographic region (i.e., provinces) or tail length. For different populations, potential health risk (characterized by hazard quotient or HQ) of MeHg exposure through crayfish consumption depended largely on crayfish consumption rates. In particular, a health hazard (HQ > 1) was found for high-rate consumers (i.e., 95 %ile or higher) in some cities in the middle and lower reaches of the Yangtze River (MLYR), during the peak consumption season. Our results suggest that more attention should be paid to dietary MeHg intake via crayfish consumption in China, particularly for communities with high consumption in MLYR.