Trading water for carbon in the future: Effects of elevated CO2 and warming on leaf hydraulic traits in a semiarid grassland.

The effects of climate change on plants and ecosystems are mediated by plant hydraulic traits, including interspecific and intraspecific variability of trait phenotypes. Yet, integrative and realistic studies of hydraulic traits and climate change are rare. In a semiarid grassland, we assessed the response of several plant hydraulic traits to elevated CO2 (+200 ppm) and warming (+1.5 to 3°C; day to night). For leaves of five dominant species (three graminoids and two forbs), and in replicated plots exposed to 7 years of elevated CO2 , warming, or ambient climate, we measured: stomatal density and size, xylem vessel size, turgor loss point, and water potential (pre-dawn). Interspecific differences in hydraulic traits were larger than intraspecific shifts induced by elevated CO2 and/or warming. Effects of elevated CO2 were greater than effects of warming, and interactions between treatments were weak or not detected. The forbs showed little phenotypic plasticity. The graminoids had leaf water potentials and turgor loss points that were 10% to 50% less negative under elevated CO2 ; thus, climate change might cause these species to adjust their drought resistance strategy away from tolerance and toward avoidance. The C4 grass also reduced allocation of leaf area to stomata under elevated CO2 , which helps explain observations of higher soil moisture. The shifts in hydraulic traits under elevated CO2 were not, however, simply due to higher soil moisture. Integration of our results with others' indicates that common species in this grassland are more likely to adjust stomatal aperture in response to near-term climate change, rather than anatomical traits; this contrasts with apparent effects of changing CO2 on plant anatomy over evolutionary time. Future studies should assess how plant responses to drought may be constrained by the apparent shift from tolerance (via low turgor loss point) to avoidance (via stomatal regulation and/or access to deeper soil moisture).

Genetic and functional variation across regional and local scales is associated with climate in a foundational prairie grass.

Global change forecasts in ecosystems require knowledge of within-species diversity, particularly of dominant species within communities. We assessed site-level diversity and capacity for adaptation in Bouteloua gracilis, the dominant species in the Central US shortgrass steppe biome. We quantified genetic diversity from 17 sites across regional scales, north to south from New Mexico to South Dakota, and local scales in northern Colorado. We also quantified phenotype and plasticity within and among sites and determined the extent to which phenotypic diversity in B. gracilis was correlated with climate. Genome sequencing indicated pronounced population structure at the regional scale, and local differences indicated that gene flow and/or dispersal may also be limited. Within a common environment, we found evidence of genetic divergence in biomass-related phenotypes, plasticity, and phenotypic variance, indicating functional divergence and different adaptive potential. Phenotypes were differentiated according to climate, chiefly median Palmer Hydrological Drought Index and other aridity metrics. Our results indicate conclusive differences in genetic variation, phenotype, and plasticity in this species and suggest a mechanism explaining variation in shortgrass steppe community responses to global change. This analysis of B. gracilis intraspecific diversity across spatial scales will improve conservation and management of the shortgrass steppe ecosystem in the future.

Prospective evaluation of the incidence of delayed nausea and vomiting in patients with colorectal cancer receiving oxaliplatin-based chemotherapy.

PURPOSE: This study sought to prospectively determine the frequency of delayed nausea and vomiting with oxaliplatin-based chemotherapy following day 1 prophylaxis with a 5-HT-(3) receptor antagonist and dexamethasone. METHODS: Patients with colon cancer, ≥ age 18, with a performance status ≤ 2, receiving oxaliplatin (85-100 mg/m(2)) as part of a standard folinic acid, 5-fluorouracil, oxaliplatin regimen for the first time were eligible. All patients received a 5-HT(3) receptor antagonist and dexamethasone 20 mg on day 1 prior to oxaliplatin. No routine prophylaxis for delayed emesis was given. Antiemetic outcome was recorded in patient-completed diaries for the 120-h study period following oxaliplatin administration. Primary endpoint was frequency of delayed (24-120 h) emesis (vomiting/retching). RESULTS: Forty-one patients were enrolled and 39 are evaluable. Median age was 70 (34-85) and the female/male ratio was 20:19. Four patients (10%) experienced vomiting or retching during the delayed period. One patient vomited during the first 24 h after oxaliplatin. The overall (120 h) no emesis rate was 87% (34/39). Twenty-one patients (54%) developed delayed nausea. Nine patients had moderate or severe nausea. Eighteen patients (46%) took rescue antiemetics during the delayed period. Delayed and overall complete response (no emesis or use of rescue antiemetics) rates were 54% and 49%, respectively. CONCLUSIONS: The use of a 5-HT(3) antagonist and dexamethasone prior to oxaliplatin results in excellent control of nausea and vomiting (CR-90%) during the 24 h after chemotherapy. However, without further antiemetic treatment, complete response in the delayed period decreased to 54%. This study supports the need for routine antiemetic prophylaxis for delayed nausea and vomiting following oxaliplatin-based chemotherapy.

Drought-Induced Root Pressure in Sorghum bicolor.

Root pressure, also manifested as profusive sap flowing from cut stems, is a phenomenon in some species that has perplexed biologists for much of the last century. It is associated with increased crop production under drought, but its function and regulation remain largely unknown. In this study, we investigated the initiation, mechanisms, and possible adaptive function of root pressure in six genotypes of Sorghum bicolor during a drought experiment in the greenhouse. We observed that root pressure was induced in plants exposed to drought followed by re-watering but possibly inhibited by 100% re-watering in some genotypes. We found that root pressure in drought stressed and re-watered plants was associated with greater ratio of fine: coarse root length and shoot biomass production, indicating a possible role of root allocation in creating root pressure and adaptive benefit of root pressure for shoot biomass production. Using RNA-Seq, we identified gene transcripts that were up- and down-regulated in plants with root pressure expression, focusing on genes for aquaporins, membrane transporters, and ATPases that could regulate inter- and intra-cellular transport of water and ions to generate positive xylem pressure in root tissue.

Aprepitant as salvage antiemetic therapy in breast cancer patients receiving doxorubicin and cyclophosphamide.

GOALS OF WORK: To assess the efficacy of adding aprepitant to a 5-HT(3) antagonist and dexamethasone as salvage antiemetic therapy for breast cancer patients receiving their initial cycle of an anthracycline and cyclophosphamide (AC) and failing to achieve complete control of emesis. MATERIALS AND METHODS: Eligibility: breast cancer patients receiving their first cycle of AC. TREATMENT: standard dose of a 5-HT(3) antagonist and dexamethasone 8-10 mg IV/PO on day 1 prior to cycle 1 of AC and dexamethasone 4 mg bid on days 2 and 3. Patients without complete control (no emesis, no nausea, or rescue antiemetics) during cycle 1 could proceed to cycle 2. During cycle 2, patients received AC and identical antiemetics (except dexamethasone 4 mg qd on days 2 and 3) plus aprepitant 125 mg PO day 1 and 80 mg PO days 2 and 3. Primary endpoint: complete control, 0-120 h after chemotherapy. RESULTS: Sixty-two patients received cycle 1 of AC. Complete control cycle 1: 13 patients (21%; 95%CI, 12-33%). Of the 49 patients eligible for cycle 2, four elected not to continue on study. Of the 45 patients receiving cycle 2, 44 were evaluable. Complete control and complete response (no emesis, no rescue) for the 5-day study period improved from 0% to 18% (p = 0.14) and 7% to 36% (p = 0.02) on cycles 1 and 2, respectively. CONCLUSIONS: In breast cancer patients receiving AC, the addition of aprepitant to a 5-HT(3) antagonist and dexamethasone during cycle 2 of treatment improved antiemetic outcome. Although the improvement in the primary endpoint of complete control during cycle 2 was not significant, all secondary endpoints such as complete response and no emesis rates were significantly better during cycle 2. The extent of antiemetic control during cycle 2 was numerically inferior to the results achieved in a phase III trial employing aprepitant with cycle 1 of AC chemotherapy, suggesting that the preferred approach is to include aprepitant with the initial cycle of AC chemotherapy.

Intraoperative radiation therapy as part of planned monotherapy for early-stage breast cancer.

INTRODUCTION: Adjuvant whole breast radiation therapy has developed into the standard of care for patients following a lumpectomy for early-stage breast cancer. However, there is recent interest in intraoperative radiation therapy (IORT) to minimize toxicity while still improving local control beyond surgical resection and anti-estrogen therapy alone. MATERIALS AND METHODS: All patients were evaluated pre-operatively in a multidisciplinary clinic setting at a community hospital for suitability for breast conservation therapy. A total of 109 patients were reviewed receiving 110 IORT treatments. Patients were followed with clinical breast examinations and mammography as clinically indicated. RESULTS: At a median follow-up of 29.9 months, 2/110 (1.8%) patients experienced a local failure. One patient (0.9%) experienced a regional failure. Local control, disease-free survival and overall survival at 3 years were 98.9% (95%CI 92.2-99.8), 97.2% (95%CI 88.9-99.3), and 96.0% (95%CI 84.9-99.0), respectively. Five-year local control, disease-free survival, and overall survival rates were 96.3% (95%CI 84.7-99.2), 94.6% (95%CI 83.2-98.3), and 92.5% (95%CI 80.4-97.3), respectively. Patient self-reported cosmetic outcome was available for 51 patients, with all patients reporting being either very pleased, pleased, or satisfied with their cosmetic outcome, and no patients reported being dissatisfied or worse. CONCLUSIONS: The results of our series suggest the feasibility of utilizing IORT in a community-based cancer center with a high degree of local control, and patient satisfaction with regard to cosmesis. While the results of this series suggest that IORT may be a promising modality, longer follow-up is warranted to better understand exactly which clinicopathological features can predict long-term locoregional disease control.