The impact of ferritin on the disassociation of HbA1c and mean plasma glucose.

OBJECTIVE: To explore the impact of ferritin level on the disassociation of glycated hemoglobin A1c (HbA1c) and mean plasma glucose (MPG). RESEACH DESIGN AND METHODS: We used a 2012-2013 cross-sectional survey conducted in Pinggu district, Beijing including 3095 Chinese participants aged 25-75 years. We categorized their glycemic status by interviewing for diagnosed diabetes and by measuring HbA1c, fasting plasma glucose (FPG), and 2-hours post-load plasma glucose (2-hours PPG). We fitted a multivariable regression model to explore the impact of ferritin on the association of HbA1c or glycated albumin (GA) and mean plasma glucose. RESULTS: A total of 5.65% of participants were diagnosed as diabetes using HbA1c criteria, and 9.79% using oral glucose tolerance test criteria. Compared with males, females had significantly lower hemoglobin levels (159.82 ± 11.56 vs 135.93 ± 12.62) and lower ferritin levels (113.00 [68.55, 185.50] vs 33.40 [12.40, 70.13]). Linear regression analysis performed in different groups classified by different diagnose criterion indicated that the correlation between MPG and HbA1c differs in different tertiles of ferritin (lowest vs middle vs highest: R2 = 0.507 vs 0.645 vs 0.687 in female; R2 = 0.415 vs 0.715 vs 0.615 in male), and the association between MPG and HbA1c diminished in the lowest tertile of ferritin. CONCLUSIONS: Ferritin level might affect the association between glucose and HbA1c, which should be taken into account when using HbA1c as a diagnosis criterion for diabetes and prediabetes.

A multi-center randomized controlled trial of the LenoMed ATA-I-1-0 insulin pump for the intensive treatment of diabetic patients.

BACKGROUND: Continuous subcutaneous insulin infusion (CSII) is an effective method for managing diabetes. The aim of this study was to evaluate the efficacy and safety of the LenoMed ATA-I-1-0 insulin pump for the treatment of patients with type 1 and type 2 diabetes, compared to the Medtronic MMT-712 insulin pump. METHODS: A total of 120 subjects with diabetes needing insulin treatment were recruited, and 104 completed the trial. The intervention and control group used the LenoMed and Medtronic insulin pump, respectively. The primary outcome was a reduction in fasting plasma glucose. Secondary outcomes included blood glucose control at 7 time points (before and after each meal, and before sleep), hemoglobin A1c (HbA1c) levels at 1 time point, and accuracy and safety of the pumps. RESULTS: In the per protocol set of 104 subjects, a significant drop in fasting plasma glucose levels was observed for 98.0% subjects in the intervention group and 92.7% in the control group. There was no statistically significant difference between groups [5.23%; 95% confidence interval (CI): -2.69% -13.2%]. Compared to baseline, levels of blood glucose and HbA1c dropped (P<0.001) at a similar magnitude in both groups. The accuracy and alarm effectiveness was 100%. No adverse event or severe adverse event related to the medication occurred in the study. CONCLUSIONS: The novel injection equipment, the LenoMed ATA-I-1-0 insulin pump, demonstrated efficacy and a good safety profile, and was not inferior to the widely used Medtronic MMT-712 insulin pump. Thus, our study suggests that the LenoMed ATA-I-1-0 insulin pump can be widely used in clinical practice.

The coupling interaction of NO2- with NH4+ or NO3- as an important source of N2O emission from agricultural soil in the North China Plain.

NO2- plays a crucial role in regulating N2O formation from the soil, while how it affects the production of soil N2O is still not well understood. In this study, N2O and NO emissions from an agricultural field of the North China Plain (NCP) were comparatively investigated under five different fertilizer treatments (NH4+, NO3-, NO2-, NH4+ + NO2- and NO3- + NO2-). Additionally, soil NH4+, NO2- and NO3- concentrations and the abundance of functional genes associated with nitrogen cycling were also analyzed in the incubation experiment. The results showed that the N2O average fluxes from the complex treatments of NO2- + NO3- were 1.4-2.4 times the sum of those from the separate treatments of NO2- and NO3- whereas from the complex treatments of NO2- + NH4+ were a factor of 1-1.4 larger than those from the separate treatments of NO2- and NH4+, indicating the coupling interaction of NO2- with NH4+ or NO3- makes a remarkable contribution to N2O emission from the soil. Significant reduction of the activity of N2O reductase was found in the soil with the addition of NO2-, which favored the accumulation of N2O formed through nitrification of NH4+ and denitrification of NO2-, resulting in relatively high N2O emissions from the complex treatments. As the intermediate product of nitrification and denitrification, NO2- produced is also expected to interact with NH4+ or NO3- to promote N2O emission from the soil, especially during fertilization events when NO2- is easily accumulated due to the acceleration of the nitrification and denitrification processes.

Elevational diversity and distribution of ammonia-oxidizing archaea community in meadow soils on the Tibetan Plateau.

Unraveling elevational diversity patterns of plants and animals has long been attracting scientific interests. However, whether soil microorganisms exhibit similar elevational patterns remains largely less explored, especially for functional microbial communities, such as ammonia oxidizers. Here, we investigated the diversity and distribution pattern of ammonia-oxidizing archaea (AOA) in meadow soils along an elevation gradient from 4400 m to the grassline at 5100 m on the Tibetan Plateau using terminal restriction fragment length polymorphism (T-RFLP) and sequencing methods by targeting amoA gene. Increasing elevations led to lower soil temperature and pH, but higher nutrients and water content. The results showed that AOA diversity and evenness monotonically increased with elevation, while richness was relatively stable. The increase of diversity and evenness was attributed to the growth inhibition of warm-adapted AOA phylotypes by lower temperature and the growth facilitation of cold-adapted AOA phylotypes by richer nutrients at higher elevations. Low temperature thus played an important role in the AOA growth and niche separation. The AOA community variation was explained by the combined effect of all soil properties (32.6%), and 8.1% of the total variation was individually explained by soil pH. The total AOA abundance decreased, whereas soil potential nitrification rate (PNR) increased with increasing elevations. Soil PNR positively correlated with the abundance of cold-adapted AOA phylotypes. Our findings suggest that low temperature plays an important role in AOA elevational diversity pattern and niche separation, rising the negative effects of warming on AOA diversity and soil nitrification process in the Tibetan region.

Diversity and succession of autotrophic microbial community in high-elevation soils along deglaciation chronosequence.

Global warming has resulted in substantial glacier retreats in high-elevation areas, exposing deglaciated soils to harsh environmental conditions. Autotrophic microbes are pioneering colonizers in the deglaciated soils and provide nutrients to the extreme ecosystem devoid of vegetation. However, autotrophic communities remain less studied in deglaciated soils. We explored the diversity and succession of the cbbL gene encoding the large subunit of form I RubisCO, a key CO2-fixing enzyme, using molecular methods in deglaciated soils along a 10-year deglaciation chronosequence on the Tibetan Plateau. Our results demonstrated that the abundance of all types of form I cbbL (IA/B, IC and ID) rapidly increased in young soils (0-2.5 years old) and kept stable in old soils. Soil total organic carbon (TOC) and total nitrogen (TN) gradually increased along the chronosequence and both demonstrated positive correlations with the abundance of bacteria and autotrophs, indicating that soil TOC and TN originated from autotrophs. Form IA/B autotrophs, affiliated with cyanobacteria, exhibited a substantially higher abundance than IC and ID. Cyanobacterial diversity and evenness increased in young soils (<6 years old) and then remained stable. Our findings suggest that cyabobacteria play an important role in accumulating TOC and TN in the deglaciated soils.

Diversity and distribution of autotrophic microbial community along environmental gradients in grassland soils on the Tibetan Plateau.

Soil microbial autotrophs play a significant role in CO2 fixation in terrestrial ecosystem, particularly in vegetation-constrained ecosystems with environmental stresses, such as the Tibetan Plateau characterized by low temperature and high UV. However, soil microbial autotrophic communities and their driving factors remain less appreciated. We investigated the structure and shift of microbial autotrophic communities and their driving factors along an elevation gradient (4400-5100 m above sea level) in alpine grassland soils on the Tibetan Plateau. The autotrophic microbial communities were characterized by quantitative PCR, terminal restriction fragment length polymorphism (T-RFLP), and cloning/sequencing of cbbL genes, encoding the large subunit for the CO2 fixation protein ribulose-1,5-bisphosphate carboxylase/oxygenase (RubisCO). High cbbL gene abundance and high RubisCO enzyme activity were observed and both significantly increased with increasing elevations. Path analysis identified that soil RubisCO enzyme causally originated from microbial autotrophs, and its activity was indirectly driven by soil water content, temperature, and NH4 (+) content. Soil autotrophic microbial community structure dramatically shifted along the elevation and was jointly driven by soil temperature, water content, nutrients, and plant types. The autotrophic microbial communities were dominated by bacterial autotrophs, which were affiliated with Rhizobiales, Burkholderiales, and Actinomycetales. These autotrophs have been well documented to degrade organic matters; thus, metabolic versatility could be a key strategy for microbial autotrophs to survive in the harsh environments. Our results demonstrated high abundance of microbial autotrophs and high CO2 fixation potential in alpine grassland soils and provided a novel model to identify dominant drivers of soil microbial communities and their ecological functions.

Impact of reclaimed water irrigation on antibiotic resistance in public parks, Beijing, China.

The abundance and distribution of antibiotics and antibiotic resistance genes (ARGs) in soils from six parks using reclaimed water in Beijing, China, were characterized. Three classes of commonly used antibiotics (tetracycles, quinolones, and sulfonamides) were analyzed by liquid chromatography-tandem mass spectrometry (LC-MS/MS). The highest concentrations of tetracyclines and quinolones were 145.2 µg kg(-1) and 79.2 µg kg(-1), respectively. Detected tetG, tetW, sulI, and sulII genes were quantified by quantitative PCR. ARGs exhibited various abundances for different park soils. The integrase gene (intI1) as an indicator of horizontal gene transfer potential was also detected in high abundance, and had significant positive correlation with tetG, sulI, and sulII genes, suggesting that intI1 may be involved in ARGs dissemination. Both sulII and intI1 clones had high homology with some classes of pathogenic bacteria, such as Klebsiella oxytoca, Acinetobacter baumannii, Shigella flexneri, which could trigger potential public health concern.

Effect of long-term wastewater irrigation on potential denitrification and denitrifying communities in soils at the watershed scale.

Wastewater irrigation mitigates the problem of water shortage but leads to the potential accumulation of pollutants and causes corresponding changes in denitrifying communities and denitrification, hence the potential ecological risk of long-term wastewater irrigation should not be overlooked. We investigated the relative contributions of different environmental factors to the abundance and diversity of denitrifying communities harboring nirK, nirS, and nosZ genes and the relative importance of these biotic and abiotic variables in potential denitrification activity (PDA) in soils with wastewater irrigation for around 25 years at a large watershed scale. Results showed that soil physicochemical properties, pollutants, including heavy metals and PAHs, and vegetation are the major factor groups influencing the abundance and structure of the three denitrifying communities and PDA. NirK-, nirS-, or nosZ-harboring denitrifiers responded in different manners to environmental changes, and were mainly influenced by substrate concentration, carbon source, or pollutants, respectively. The structure of the three denitrifying communities was more relevant to the environmental changes than their abundance. Conversely, the abundance, rather than diversity, was correlated with PDA. Pollutants and vegetation could affect PDA by both direct and indirect paths through soil physicochemical properties including pH, carbon and nitrogen sources, or through the abundance of denitrifying functional genes. The abundance of denitrifying functional genes is a valuable index that integrates potential activity and various environmental factors, and is therefore a good predictor of denitrification in the presence of environmental changes.

Diverse and abundant antibiotic resistance genes in Chinese swine farms.

Antibiotic resistance genes (ARGs) are emerging contaminants posing a potential worldwide human health risk. Intensive animal husbandry is believed to be a major contributor to the increased environmental burden of ARGs. Despite the volume of antibiotics used in China, little information is available regarding the corresponding ARGs associated with animal farms. We assessed type and concentrations of ARGs at three stages of manure processing to land disposal at three large-scale (10,000 animals per year) commercial swine farms in China. In-feed or therapeutic antibiotics used on these farms include all major classes of antibiotics except vancomycins. High-capacity quantitative PCR arrays detected 149 unique resistance genes among all of the farm samples, the top 63 ARGs being enriched 192-fold (median) up to 28,000-fold (maximum) compared with their respective antibiotic-free manure or soil controls. Antibiotics and heavy metals used as feed supplements were elevated in the manures, suggesting the potential for coselection of resistance traits. The potential for horizontal transfer of ARGs because of transposon-specific ARGs is implicated by the enrichment of transposases--the top six alleles being enriched 189-fold (median) up to 90,000-fold in manure--as well as the high correlation (r(2) = 0.96) between ARG and transposase abundance. In addition, abundance of ARGs correlated directly with antibiotic and metal concentrations, indicating their importance in selection of resistance genes. Diverse, abundant, and potentially mobile ARGs in farm samples suggest that unmonitored use of antibiotics and metals is causing the emergence and release of ARGs to the environment.

Effect of pyrene on denitrification activity and abundance and composition of denitrifying community in an agricultural soil.

Toxicity of pyrene on the denitrifiers was studied by spiking an agricultural soil with pyrene to a series of concentrations (0-500 mg kg(-1)) followed by dose-response and dynamic incubation experiments. Results showed a positive correlation between potential denitrification activity and copy numbers of denitrifying functional genes (nirK, nirS and nosZ), and were both negatively correlated with pyrene concentrations. Based on the comparison of EC(50) values, denitrifiers harboring nirK, nirS or nosZ gene were more sensitive than denitrification activity, and denitrifiers harboring nirS gene were more sensitive than that harboring nirK or nosZ genes. Seven days after spiking with EC(50) concentration of pyrene, denitrifiers diversity decreased and community composition changed in comparison with the control. Phylogenetic analyses of three genes showed that the addition of pyrene increased the proportion of Bradyrhizobiaceae, Rhodospirillales, Burkholderiales and Pseudomonadales. Some species belonging to these groups were reported to be able to degrade PAHs.