Stability of tropical forest tree carbon-water relations in a rainfall exclusion treatment through shifts in effective water uptake depth.

Increasing severity and frequency of drought is predicted for large portions of the terrestrial biosphere, with major impacts already documented in wet tropical forests. Using a 4-year rainfall exclusion experiment in the Daintree Rainforest in northeast Australia, we examined canopy tree responses to reduced precipitation and soil water availability by quantifying seasonal changes in plant hydraulic and carbon traits for 11 tree species between control and drought treatments. Even with reduced soil volumetric water content in the upper 1 m of soil in the drought treatment, we found no significant difference between treatments for predawn and midday leaf water potential, photosynthesis, stomatal conductance, foliar stable carbon isotope composition, leaf mass per area, turgor loss point, xylem vessel anatomy, or leaf and stem nonstructural carbohydrates. While empirical measurements of aboveground traits revealed homeostatic maintenance of plant water status and traits in response to reduced soil moisture, modeled belowground dynamics revealed that trees in the drought treatment shifted the depth from which water was acquired to deeper soil layers. These findings reveal that belowground acclimation of tree water uptake depth may buffer tropical rainforests from more severe droughts that may arise in future with climate change.

The association of Medicare health care delivery systems with stage at diagnosis and survival for patients with melanoma.

OBJECTIVE: To evaluate differences in the stage at diagnosis and survival for melanoma between the 2 most common types of Medicare health care delivery systems, fee-for-service (FFS) and managed care (health maintenance organizations [HMOs]), in the United States during the period from January 1, 1985, through December 31, 1994. DESIGN: We used a linkage of 2 national databases, ie, the Medicare database from the Centers for Medicare and Medicaid Services (formerly the Health Care Financing Administration) and the National Cancer Institute Surveillance, Epidemiology, and End Results program database, to evaluate differences in demographic data, stage at diagnosis, and survival for melanoma between the HMO and FFS groups. Patients A population of 4608 patients (62% men; 92% white). RESULTS: We found an earlier stage of diagnosis for the HMO group compared with the FFS group for melanoma as the first cancer diagnosis, but this did not persist when melanoma was the second or a later cancer diagnosis. For patients with melanoma as the first cancer diagnosis, improved survival was related to earlier stage at diagnosis. CONCLUSIONS: Differences exist in stage at diagnosis between patients in HMOs compared with those in FFS health care plans. This is likely due in part to utilization of services or access to care for patients in HMOs, and may be similar to that of patients in FFS plans with a previous cancer diagnosis before their diagnosis of melanoma. We did not find an increased risk of diagnosis with a late-stage cancer among patients with vs those without a previous cancer diagnosis. Improved survival appears to be related to earlier stage at diagnosis.

Open-label pilot study of alitretinoin gel 0.1% in the treatment of photoaging.

Alitretinoin (9-cis-retinoic acid) is an FDA-approved topical therapy for the treatment of Kaposi sarcoma. Alitretinoin is a naturally occurring endogenous retinoid that binds to and activates all known intracellular retinoic acid receptor (RAR) subtypes alpha, beta, and gamma and retinoic X receptor (RXR) subtypes alpha, beta, and gamma. Photoaging of the skin is the result of accumulated exposure to solar UV radiation. Several topically applied retinoids have been proven clinically effective for treating the appearance of photoaging. Tretinoin and tazarotene, which have been shown to improve photodamaged skin, bind RAR subtypes only. The theoretic benefit of alitretinoin gel 0.1% (Panretin) in the treatment of photoaged skin stems from the binding and activation of both RARs and RXRs, which promote the repair mechanisms in damaged skin. The objective of this study was to evaluate the safety and efficacy of topical alitretinoin gel 0.1% in the treatment of photodamaged skin. The treatment was well tolerated by participants (N=20) and subjectively showed improvement of benign skin lesions (eg, seborrheic keratoses) and precancerous lesions (eg, actinic keratoses). Larger, blinded, controlled trials are needed to investigate the role of this novel retinoid in the treatment of photoaging.