Studies of tree recruitment are many, but they provide few general insights into the role of recruitment limitation for population dynamics. That role depends on the vital rates (transitions) from seed production to sapling stages and on overall population growth. To determine the state of our understanding of recruitment limitation we examined how well we can estimate parameters corresponding to these vital rates. Our two-part analysis consists of (1) a survey of published literature to determine the spatial and temporal scale of sampling that is basis for parameter estimates, and (2) an analysis of extensive data sets to evaluate sampling intensity found in the literature. We find that published studies focus on fine spatial scales, emphasizing large numbers of small samples within a single stand, and tend not to sample multiple stands or variability across landscapes. Where multiple stands are sampled, sampling is often inconsistent. Sampling of seed rain, seed banks, and seedlings typically span <1 yr and rarely last 5 yr. Most studies of seeding establishment and growth consider effects of a single variable and a single life history stage. By examining how parameter estimates are affected by the spatial and temporal extent of sampling we find that few published studies are sufficiently extensive to capture the variability in recruitment stages. Early recruitment stages are especially variable and require samples across multiple years and multiple stands. Ironically, the longest duration data sets are used to estimate mortality rates, which are less variable (in time) than are early life history stages. Because variables that affect recruitment rates interact, studies of these interactions are needed to assess their full impacts. We conclude that greater attention to spatially extensive and longer duration sampling for early life history stages is needed to assess the role of recruitment limitation in forests.

Prophylactic pyridoxine (vitamin B6), given concomitantly with capecitabine-containing chemotherapy, was not effective for the prevention of HFS.

9085 Background: Capecitabine is an oral fluoropyrimidine that is used to treat various malignancies. Hand and Foot Syndrome (HFS) is a dose limiting toxicity of capecitabine and can limit the use of this agent in some patients. Some investigators have observed that pyridoxine (vitamin B6) can ameliorate HFS caused by capecitabine. We designed a prospective trial to determine if pyridoxine can prevent HFS in patients receiving capecitabine. Methods: In our double-blind, placebo controlled trial, we randomly assigned eligible patients treated with capecitabine to receive either daily pyridoxine 100 mg or placebo along with their capecitabine-containing chemotherapy regimen. Patients were observed during the first four cycles of capecitabine treatment. The primary end point was the incidence and grade of HFS that occurred in both arms. Results: Between 2008 and 2011, 77 patients were randomly assigned to receive either pyridoxine (n=38) or placebo (n=39). Both arms were matched in baseline characteristics. The median age was 53.5 years. The ethnic composition of the study population was African American 53%, Caucasian 22%, Hispanic 18%, and Asian 7%. The daily doses of capecitabine were: 2000 mg/m2 (69 pts), 1650 mg/m2 (5 pts), 1400 mg/m2 (2 pts) and 1000 mg/m2 (1 pt). Dosages of capecitabine were equally matched between the two arms of the study. HFS occurred after a median of 2 chemotherapy cycles in both groups. HFS developed in 10/38 (26%) patients in the pyridoxine group and in 8/39 (20%) patients in the placebo group (p=0.547). Therefore, the risk of HFS was 6 percentage points higher in pyridoxine group (95% CI for difference: -13 percentage points to +25 percentage points). Given our study results, we can be confident of excluding a true benefit from pyridoxine larger than 13 percentage points. No difference in HFS grades was observed. Conclusions: Prophylactic pyridoxine (vitamin B6), given concomitantly with capecitabine-containing chemotherapy, was not effective for the prevention of HFS. [Table: see text]

No abstract

The delineation of ground beef batches has implications for the management of product disposition policies in the event of Shiga toxin-producing Escherichia coli contamination. Analysis of individual contributor animal-specific DNA profiles can provide valuable empirical data for understanding the dynamics of ground meat production processes and can act as a surrogate for cross-contamination. A genetic method was developed for characterizing the source raw material flow and carryover between discrete batches of ground beef in a large-scale commercial beef grinding operation. The application developed involves the introduction of a genetically distinct source raw material batch into the grinding system and comprehensive sampling of that index batch and subsequent batches followed by single nucleotide polymorphism genotyping of random subsamples. Capture-mark-recapture statistical techniques were used to estimate (i) the number of carcass contributors and (ii) the associated level of carryover between batches. Carryover, expressed as a percentage of the total weight of the batch material (in pounds), was observed between the genetically distinct index batch and the next sequential batch at approximately 1%. The nondetection of additional carryover to subsequent batches, with a detection level of approximately 0.2%, supports a serial dilution model of same source raw material carryover, consistent with the recorded weight of beef trimmings used in each batch. For ground beef manufacturers, this method is a simple approach for validating the independence of finished batches of beef in their grind systems in support of product disposition policies.