Interactions between nitrogen and phosphorus in modulating soil respiration: A meta-analysis.

BACKGROUND: Economic and social development worldwide increases the input of nutrients, especially nitrogen (N) and phosphorus (P), to soils. These nutrients affect soil respiration (Rs) in terrestrial ecosystems. They may act independently or have interactive effects on Rs. The effect of N and P on Rs and its components (autotrophic respiration [Ra] and heterotrophic respiration [Rh]), however, either individually or together, is poorly understood. We performed a meta-analysis of 130 studies to examine the effects of different fertilization treatments on Rs and its components across terrestrial ecosystems. RESULTS: Our results showed that (1) The impact of fertilizer addition on Rs varies among different fertilizer types. N addition reduced Rs and Rh significantly but did not affect Ra; P addition had no significant effect on Rs, Rh, and Ra; NP addition increased Rs significantly but did not affect Rh and Ra. (2) Ecosystem type, duration of fertilization, fertilization rate, and fertilizer form influenced the response of Rs and its components to fertilizer application. (3) Based on our study, the annual average temperature may be a driving factor of Rs response to fertilizer addition, while soil total nitrogen may be an important predictor of Rs response to fertilizer addition. CONCLUSION: Overall, our study highlights the complex and multifaceted nature of the response of soil Rs and its components to fertilizer application, underscoring the importance of considering multiple factors when predicting and modeling future Rs and its feedback to global change.

C-reactive protein (CRP) is a predictor of high medical-care expenditures in a community-based elderly population aged 70 years and over: the Tsurugaya project.

Because CRP is a strong independent predictor of various diseases, it was hypothesized that CRP may be a useful predictor or treatment target for medical-care expenditures. The aim of this study was to investigate the relationship between CRP and medical-care expenditures in a community-dwelling elderly population. This prospective cohort study was conducted including 925 Japanese subjects aged ≥70 years. A high-sensitivity CRP assay was used by applying the nephelometric method. Hospitalizations, outpatient visits, and expenditures were ascertained through computerized linkage with claims lodged between August 2002 and March 2008 with the Miyagi National Health Insurance (NHI) Association. Since medical-care expenditures were not normally distributed, the category of high medical-care expenditures (>75th percentile of medical-care expenditures: inpatient expenditures >$494/month; outpatient expenditure >$522/month; total expenditures >$1103/month) was used to examine the relation of CRP levels with medical-care expenditures. Multiple logistic regression analysis was used to examine the relationship between CRP cutoff points (low concentrations: <1.0mg/L; intermediate concentrations: 1.0-3.0mg/L; or high concentrations: ≥3.0 mg/L) and medical-care expenditures during 6 year-follow up period. After adjustment for potential confounding factors, a positive association of CRP with hospitalization, and total expenditures (p for trend=0.03 and 0.02, respectively) was found. An elevated baseline CRP level is an independent predictor of increases in prospective medical-care expenditures among community-dwelling elderly. Further study is required to clarify whether reducing CRP by intervention is a cost-effective measure.