In this task, you are given a passage which has a question and the context. You have to generate an answer to the question based on the information present in the context.

Context: Allergic rhinitis (AR) is a complex chronic inflammatory disease of the nasal mucosa, caused by an interaction between genetic and environmental factors. As evidence suggests that some genetic variants may increase susceptibility to both AR and asthma, the objective of this study was to identify asthma susceptibility variants associated with AR in the Chinese population.', 'A cohort of 402 individuals with physician-diagnosed AR and 416 healthy controls were recruited from the Han Chinese population in Beijing. DNA was extracted from the peripheral blood and a total of 12 single-nucleotide polymorphisms (SNPs) shown to be associated with asthma in Japanese subjects were selected for genotyping using the SequenomMassARRAY technology platform.', 'Analysis of frequency differences of allele between the AR patients and control subjects showed that the C allele of rs204993 in the pre-B-cell leukemia homeobox 2 (PBX2) gene from the 6p21.3 locus was significantly associated with AR (p = 0.0006, pcorrected = 0.0340). Genotype analysis further confirmed the difference in distribution of this variant between AR patients and controls in the both the dominant (pT/C+C/C vs T/T = 7.37×10(-5) ) and co-dominant (pT/C vs T/T = 1.98 × 10(-4) , pC/C vs T/T = 0.004) models.\Question: Does variant of PBX2 gene in the 6p21.3 asthma susceptibility locus is associate with allergic rhinitis in Chinese subjects?
These results suggest that the PBX2 gene in the 6p21.3 asthma susceptibility locus may be associated with increased risk for both AR and asthma in Chinese subjects.

Context: Eradication of Helicobacter pylori is not routinely recommended for the symptomatic relief and the prevention of gastric cancer in patients with functional dyspepsia. The present study investigated a useful indicator of H. pylori eradication in such patients by determining the optimal cutoff value of a 13C-urea breath test (UBT).', 'One hundred dyspeptic patients participated in the study. Dyspepsia was scored, and a 13C-UBT administered. A level of delta 13C-UBT of>4 per thousand was diagnosed as H. pylori-positive. After the stomach was endoscopically sprayed with phenol red, biopsy specimens were taken from the antrum, body and cardia of the stomach for the assessment of H. pylori density, and activity (neutrophil infiltration) and degree (lymphocyte infiltration) of gastritis.', 'Correlation between delta 13C-UBT and dyspepsia score was not found. Delta 13C-UBT significantly correlated with H. pylori density score in the total stomach (r = 0.53, P < 0.0001), neutrophil (r = 0.34, P = 0.0005) and lymphocyte score (r = 0.69, P < 0.0001). Twenty-six of the 100 subjects had a neutrophil score of >or=4, lymphocyte score of >or=4, and H. pylori score of >or=4. Their 95% confidence interval of mean was 58.2 per thousand, which reflects moderate to marked acute and chronic gastritis, and dense H. pylori colonization.\Question: Is delta ( 13 ) C-urea breath test value a useful indicator for Helicobacter pylori eradication in patients with functional dyspepsia?
The 13C-UBT is a reliable semiquantitative test to assess H. pylori density and the activity and degree of gastritis. It is proposed that H. pylori eradication therapy might be beneficial for patients with functional dyspepsia with a delta 13C-UBT of >58.2 per thousand.

Context: Much evidence suggests that plant communities on infertile soils are relatively insensitive to increased water deficit caused by increasing temperature and/or decreasing precipitation. However, a multi-decadal study of community change in the western USA does not support this conclusion. This paper tests explanations related to macroclimatic differences, overstorey effects on microclimate, variation in soil texture and plant functional traits.', 'A re-analysis was undertaken of the changes in the multi-decadal study, which concerned forest understorey communities on infertile (serpentine) and fertile soils in an aridifying climate (southern Oregan) from 1949-1951 to 2007-2008. Macroclimatic variables, overstorey cover and soil texture were used as new covariates. As an alternative measure of climate-related change, the community mean value of specific leaf area was used, a functional trait measuring drought tolerance. We investigated whether these revised analyses supported the prediction of lesser sensitivity to climate change in understorey communities on infertile serpentine soils.', 'Overstorey cover, but not macroclimate or soil texture, was a significant covariate of community change over time. It strongly buffered understorey temperatures, was correlated with less change and averaged >50 % lower on serpentine soils, thereby counteracting the lower climate sensitivity of understorey herbs on these soils. Community mean specific leaf area showed the predicted pattern of less change over time in serpentine than non-serpentine communities.\Question: Are plant communities on infertile soils less sensitive to climate change?

Based on the current balance of evidence, plant communities on infertile serpentine soils are less sensitive to changes in the climatic water balance than communities on more fertile soils. However, this advantage may in some cases be lessened by their sparser overstorey cover.