Bacterial Community Structure Recovery in Reclaimed Coal Mined Soil under Two Vegetative Regimes.

Coal mining can be deleterious to the soil physical and chemical makeup, but also to the soil microbial community. Effectively, the removal of nearly all organic matter from the upper soil horizons reduces the effectiveness of any soil to support vegetation, and up until recently, microbial community parameters were not considered in the successful reclamation of overburden. Thus, our study proposes to measure the uncultivated bacterial community using 16S ribosomal RNA (rRNA) high-throughput sequencing in a chronosequence of reclaimed overburden in Mississippi. The study sites comprised samplings of pasture and wooded reclamation sites consisting of 1 to 13 yr post reclamation time, as well as reference sites. Overall, the primary driver of bacterial community dynamics was vegetative cover, although time also influenced dynamics. Richness estimations for operational taxonomic units (OTUs) showed that recently reclaimed (∼1 yr) and Pasture sites were more OTU rich with levels of >1400 compared with reference site levels of ∼1000. Diversity levels also followed a similar trend. Community structure typically differed between time points and vegetative cover; however, membership was similar between sites and reference, indicating that new communities still shared some membership from the previous community. Overall, physicochemical properties trended toward more positive for soil health as time progressed, but bacterial community recovery was still not structurally recovered, although richness and diversity values exceeded reference. Overall, this study demonstrated that mine reclamation using pasture and/or wood restoration can reestablish the bacterial community to approximate reference conditions, but vegetation is still the dominating environmental factor dictating microbial community.

Infliximab treatment of intravenous immunoglobulin-resistant Kawasaki disease.

OBJECTIVE: To investigate the safety, tolerability, and pharmacokinetics of the anti-tumor necrosis factor-alpha monoclonal antibody infliximab in subjects with intravenous immunoglobulin (IVIG)-resistant Kawasaki disease (KD). STUDY DESIGN: We conducted a multicenter, randomized, prospective trial of second IVIG infusion (2 g/kg) versus infliximab (5 mg/kg) in 24 children with acute KD and fever after initial treatment with IVIG. Primary outcome measures were the safety, tolerability, and pharmacokinetics of infliximab. Secondary outcome measures were duration of fever and changes in markers of inflammation. RESULTS: Study drug infusions were associated with cessation of fever within 24 hours in 11 of 12 subjects treated with infliximab and in 8 of 12 subjects retreated with IVIG. No infusion reactions or serious adverse events were attributed to either study drug. No significant differences were observed between treatment groups in the change from baseline for laboratory variables, fever, or echocardiographic assessment of coronary arteries. CONCLUSIONS: Both infliximab and a second IVIG infusion were safe and well tolerated in the subjects with KD who were resistant to standard IVIG treatment. The optimal management of patients resistant to IVIG remains to be determined.

Response of bahiagrass carbon assimilation and photosystem activity to below optimum temperatures.

Photosynthesis and growth of tropical grasses are sensitive to cool season temperatures but information on the responsive mechanisms is limited in many species including bahiagrass (Paspalum notatum Flueggé). Therefore, an experiment was conducted in sunlit, controlled environment chambers to determine the effect of below optimum temperatures on leaf net photosynthesis (A) and chlorophyll fluorescence (F) and response to internal [CO2] (Ci) and photosynthetic photon flux density (PPFD) of A and F of bahiagrass. Five day/night temperatures of 14/6, 18/10, 22/14, 26/18 and 30/22°C were imposed from 55 to 100 days after transplanting for plants grown initially for 55 days at 30/22°C. Leaf A and F were measured from 1000 to 1400 hours between -1 to 35 days after imposing temperature treatments. Leaf A-F/Ci and A-F/PPFD response curves were measured between 11 and 20 days after start of temperature treatments. After 35 days of treatment, the cold acclimation response of leaf A was assessed by lowering temperature in all treatments to 6°C and measuring A and F for a 3-day period. Repeated-measures analysis showed significant effects of time, temperature and time × temperature. The reduction of A on the first day of cold shock was 64, 37, 61, 64 and 81% in plants previously grown at 14, 18, 22, 26 and 30°C, respectively, which indicates acclimation at 18°C. Below optimum temperature significantly lowered CO2-saturated net photosynthesis (Asat), carboxylation efficiency (CE) and electron transport rate (ETR) derived from A-F/Ci curves. Below optimum temperature also lowered light-saturated photosynthesis (Amax), Rd and ETR derived from A-F/PPFD curves. The relationship between φCO2 and φPSII showed that bahiagrass A was more sensitive than electron transport at below optimum temperatures, which may be associated with increased CO2 leakage and over-cycling of C4 acid cycle. The leaf-level photosynthesis parameters and their response functions will also help to improve algorithms for simulating forage growth under variable temperature conditions.