Glycation starts from nonenzymatic amino-carbonyl reaction that binds carbonyl group of reducing sugars to the amino group of amino acids. Glycation leads to further complex reactions to form ...advanced glycation end products (AGE). Because AGE are implicated in the gradual development of diabetic complications, tissue accumulation of AGE has been widely examined in various tissues of rats. Avian species are known to have high body temperature and blood glucose concentration compared with mammals. Although these characteristics enabled chickens to be used as experimental models for diabetes mellitus, the information of AGE accumulation in various tissues of chickens has not been limited so far. In the present study, therefore, the radioactive AGE prepared by reacting 14C-glucose and amino acids were intravenously administrated, and comparison of tissue accumulation of 14C-labeled AGE was made between chickens and rats. At 30 min after administration, tissues (18–20) were collected, and the radioactivity incorporated into tissues was determined. High levels of radioactivity per gram of tissue in the liver and kidney were observed in both rats and chickens. In chickens but not rats, a large amount of 14C-labeled AGE incorporated into 1 g of spleen was observed, and the specific accumulation of AGE in the avian spleen might have a particular role in immune response in avian species.
Photo-absorption by black carbon (BC) aerosol is believed to be enhanced by the internal mixing of BC with volatile compounds. We investigate this effect quantitatively with laboratory experiments. ...Graphite particles are used as a surrogate for BC, with coatings of oleic acid and glycerol. The photo-absorption of coated graphite with known shell and core diameters are directly measured by a photo-acoustic technique. The size distribution and coating thickness are quantified using a single-particle soot photometer (SP2). The absorption is amplified by ∼30% even with a small coating thickness (shell/core diameter ratio (D
p
/D
c
) = 1.2). The amplification reaches as high as 2 at D
p
/D
c
= 2. We calculate the amplification of the absorption using a shell/core model of Mie theory. The model generally reproduces the measured amplification well.
Measurements of ambient OH and HO2 radicals were performed by laser induced fluorescence (LIF) during CAREBeijing2006 (Campaigns of Air Quality Research in Beijing and Surrounding Region 2006) at the ...suburban site Yufa in the south of Beijing in summer 2006. On most days, local air chemistry was influenced by aged air pollution that was advected by a slow, almost stagnant wind from southern regions. Observed daily concentration maxima were in the range of (4-17) × 106 cm-3 for OH and (2-24) × 108 cm-3 for HO2 (including an estimated interference of 25% from RO2 ). During daytime, OH reactivities were generally high (10-30 s-1 ) and mainly contributed by observed VOCs and their calculated oxidation products. The comparison of modelled and measured HOx concentrations reveals a systematic underprediction of OH as a function of NO. A large discrepancy of a factor 2.6 is found at the lowest NO concentration encountered (0.1 ppb), whereas the discrepancy becomes insignificant above 1 ppb NO. This study extends similar observations from the Pearl-River Delta (PRD) in South China to a more urban environment. The OH discrepancy at Yufa can be resolved, if NO-independent additional OH recycling is assumed in the model. The postulated Leuven Isoprene Mechanism (LIM) has the potential to explain the gap between modelled and measured OH at Beijing taking into account conservative error estimates, but lacks experimental confirmation. This and the hereby unresolved discrepancy at PRD suggest that other VOCs besides isoprene might be involved in the required, additional OH recycling. Fast primary production of ROx radicals up to 7 ppb h-1 was determined at Beijing which was dominated by the photolysis of O3 , HONO, HCHO, and dicarbonyls. For a special case, 20 August, when the plume of Beijing city was encountered, a missing primary HOx source (about 3 ppb h-1 ) was determined under high NOx conditions similar to other urban areas like Mexico City. CAREBeijing2006 emphasizes the important role of OVOCs as a radical source and sink, and the need for further investigation of the chemical degradation of VOCs in order to better understand radical chemistry in VOC-rich air.
Ambient OH and HO2 concentrations were measured by laser induced fluorescence (LIF) during the PRIDE-PRD2006 (Program of Regional Integrated Experiments of Air Quality over the Pearl River Delta, ...2006) campaign at a rural site downwind of the megacity of Guangzhou in Southern China. The observed OH concentrations reached daily peak values of (15-26) × 106 cm-3 which are among the highest values so far reported for urban and suburban areas. The observed OH shows a consistent high correlation with j(O1 D) over a broad range of NOx conditions. The correlation cannot be reproduced by model simulations, indicating that OH stabilizing processes are missing in current models. The observed OH exhibited a weak dependence on NOx in contrast to model predictions. While modelled and measured OH agree well at NO mixing ratios above 1 ppb, a continuously increasing underprediction of the observed OH is found towards lower NO concentrations, reaching a factor of 8 at 0.02 ppb NO. A dependence of the modelled-to-measured OH ratio on isoprene cannot be concluded from the PRD data. However, the magnitude of the ratio fits into the isoprene dependent trend that was reported from other campaigns in forested regions. Hofzumahaus et al. (2009) proposed an unknown OH recycling process without NO, in order to explain the high OH levels at PRD in the presence of high VOC reactivity and low NO. Taking a recently discovered interference in the LIF measurement of HO2 into account, the need for an additional HO2 -> OH recycling process persists, but the required source strength may be up to 20% larger than previously determined. Recently postulated isoprene mechanisms by Lelieveld et al. (2008) and Peeters and Müller (2010) lead to significant enhancements of OH expected for PRD, but an underprediction of the observed OH by a factor of two remains at low NO (0.1-0.2 ppb). If the photolysis of hydroperoxy aldehydes from isoprene is as efficient as proposed by Peeters and Müller (2010), the corresponding OH formation at PRD would be more important than the primary OH production from ozone and HONO. While the new isoprene mechanisms need to be confirmed by laboratory experiments, there is probably need for other, so far unidentified chemical processes to explain entirely the high OH levels observed in Southern China.
In situ observation of the atmospheric CO2, CH4, and CO mixing ratios at Hateruma Island (HAT, 24.05 degree N, 123.80 degree E) often show synoptic-scale variations with correlative elevations during ...winter, associated with air transport from the East Asian countries. We examine winter (November- March) trends in Delta CH4 / Delta CO2, Delta CO / Delta CO2, and Delta CO / Delta CH4 observed at Hateruma over the period 1999 to 2010. To investigate the relationship between the East Asian emissions and the short-term variations in the atmospheric mixing ratios, we use the FLEXPART Lagrangian particle dispersion model (LPDM). The observed ratios Delta CH4 / Delta CO2 and Delta CO / Delta CO2 both show an overall gradual decrease over the study period due to a recent rapid increase in fossil fuel consumption in China. We note, however, that the decreasing rates of Delta CH4 / Delta CO2 and Delta CO / Delta CO2 show gradual decrease and increase, respectively, during the entire observation periods used in this study. The Delta CO / Delta CH4 slope, on the other hand, shows an increasing trend during 1999-2004 but a decrease during 2005-2010. Calculation of the concentration footprint for the atmospheric observation at HAT by using the FLEXPART LPDM indicates that most of the short-term variations are caused by emission variations from northern and eastern China. Combined with a set of reported emission maps, we have estimated the temporal changes in the annual CH4 and CO emissions from China under the assumption that the estimate of the fossil-fuel-derived CO2 emissions based on the energy statistics are accurate. The estimated annual CH4 emissions, corresponding to nonseasonal sources or anthropogenic sources without rice fields, show a nearly constant value of 39 plus or minus 7 TgCH4 yr-1 during 1998-2002, and then gradually increase to 46 plus or minus 8 TgCH4 yr-1 in 2009/2010. The estimated annual CO emissions increase from 134 plus or minus 32 TgCO yr-1 in 1998/1999 to 182 plus or minus 42 TgCO yr-1 in 2004/2005, level off after 2005, and then slightly decrease to less than 160 TgCO yr-1 in 2008-2010.
This study was part of the international field measurement Campaigns of Air Quality Research in Beijing and Surrounding Region 2006 (CAREBeijing‐2006). We investigated a new particle formation event ...in a highly polluted air mass at a regional site south of the megacity Beijing and its impact on the abundance and properties of cloud condensation nuclei (CCN). During the 1‐month observation, particle nucleation followed by significant particle growth on a regional scale was observed frequently (∼30%), and we chose 23 August 2006 as a representative case study. Secondary aerosol mass was produced continuously, with sulfate, ammonium, and organics as major components. The aerosol mass growth rate was on average 19 μg m−3 h−1 during the late hours of the day. This growth rate was observed several times during the 1‐month intensive measurements. The nucleation mode grew very quickly into the size range of CCN, and the CCN size distribution was dominated by the growing nucleation mode (up to 80% of the total CCN number concentration) and not as usual by the accumulation mode. At water vapor supersaturations of 0.07–0.86%, the CCN number concentrations reached maximum values of 4000–19,000 cm−3 only 6–14 h after the nucleation event. During particle formation and growth, the effective hygroscopicity parameter κ increased from about 0.1–0.3 to 0.35–0.5 for particles with diameters of 40–90 nm, but it remained nearly constant at ∼0.45 for particles with diameters of ∼190 nm. This result is consistent with aerosol chemical composition data, showing a pronounced increase of sulfate.
•Dietary carbohydrate influenced colocalization pattern of GLP-1 with neurotensin.•Low carbohydrate diet modified structures of intestinal endocrine cells.•Cells containing both GLP-1 and neurotensin ...reduced in carbohydrate-free group.•Low carbohydrate diet suppressed transcription of mRNA intestinal hormones.
Glucagon-like peptide (GLP)-1 colocalizes with neurotensin (NT) in the same enteroendocrine cells (EECs) of the chicken ileum. The present study was designed to clarify the influence of dietary carbohydrate (CHO) on the colocalization pattern of GLP-1 with NT in the chicken distal ileum. Male White Leghorn chickens at 6 weeks of age (n = 15) were divided into three groups, a control and two experimental (low-CHO and CHO-free), with five chickens in each, and fed control or experimental diets for 7 d. Distal ileum was collected from each bird as a tissue sample and subjected to double immunofluorescence staining to detect GLP-1 and NT. Three types of EEC, GLP-1+/NT+, GLP-1+/NT− and GLP-1−/NT+, were demonstrated in the chicken ileum. GLP-1+/NT+ cells in the control group had a spindle-like shape with a long cytoplasmic process, but those in the experimental groups were round and lacked a cytoplasmic process. The ratio of GLP-1+/NT+ cells was significantly decreased in the two experimental groups compared with that in the control group. The ratio of GLP-1+/NT+ cells was significantly lower than those of GLP-1+/NT− and GLP-1−/NT+ cells in the two experimental groups. Most cells that were immunoreactive for GLP-1 and NT antisera lacked signals of proglucagon (PG) and NT precursor (NTP) mRNA in the experimental groups. The number of EECs expressing PG and NTP mRNA signals showed tendencies for decreases with a reduction of dietary CHO level. These findings suggest that dietary CHO could be a significant regulator of the pattern of colocalization pattern of GLP-1 with NT in the chicken ileum.
An improved understanding of the variations in the mass concentration and size distribution of black carbon (BC) in the free troposphere (FT) over East Asia, where BC emissions are very high, is ...needed to reliably estimate the radiative forcing of BC in climate models. We measured these parameters and the carbon monoxide (CO) concentration by conducting the Aerosol Radiative Forcing in East Asia (A‐FORCE) 2013W aircraft campaign in East Asia in winter 2013 and compared these data with measurements made in the same region in spring 2009. The median BC concentrations in the FT originating from North China (NC) and South China (SC) showed different seasonal variations, which were primarily caused by variations in meteorological conditions. CO concentrations above the background were much higher in SC than in NC in both seasons, suggesting a more active upward transport of CO. In SC, precipitation greatly increased from winter to spring, leading to an increased wet deposition of BC. As a result, the median BC concentration in the FT was highest in SC air in winter. This season and region were optimal for the effective transport of BC from the planetary boundary layer to the FT. The count median diameters of the BC size distributions generally decreased with altitude via wet removal during upward transport. The altitude dependence of the BC size distributions was similar in winter and spring, in accord with the similarity in the BC mixing state. The observed BC concentrations and microphysical properties will be useful for evaluating the performance of climate models.
Key Points
Seasonal variation of black carbon concentrations over East Asia is shown
Black carbon concentrations were influenced by uplift and wet deposition
The size distribution of black carbon shifted to smaller sizes with altitude
The Aerosol Radiative Forcing in East Asia (A‐FORCE) aircraft campaign was conducted over East Asia in March–April 2009. During the A‐FORCE campaign, 120 vertical profiles of black carbon (BC) and ...carbon monoxide (CO) were obtained in the planetary boundary layer (PBL) and the free troposphere. This study examines the wet removal of BC in Asian outflow using the A‐FORCE data. The concentrations of BC and CO were greatly enhanced in air parcels sampled at 3–6 km in altitude over the Yellow Sea on 30 March 2009, associated with upward transport due to a cyclone with modest amounts of precipitation over northern China. In contrast, high CO concentrations without substantial enhancements of BC concentrations were observed in air parcels sampled at 5–6 km over the East China Sea on 23 April 2009, caused by uplifting due to cumulus convection with large amounts of precipitation over central China. The transport efficiency of BC (TEBC, namely the fraction of BC particles not removed during transport) in air parcels sampled above 2 km during the entire A‐FORCE period decreased primarily with the increase in the precipitation amount that air parcels experienced during vertical transport, although their correlation was modest (r2 = 0.43). TEBC also depended on the altitude to which air parcels were transported from the PBL and the latitude where they were uplifted locally over source regions. The median values of TEBC for air parcels originating from northern China (north of 33°N) and sampled at 2–4 km and 4–9 km levels were 86% and 49%, respectively, during the A‐FORCE period. These median values were systematically greater than the corresponding median values (69% and 32%, respectively) for air parcels originating from southern China (south of 33°N). Use of the A‐FORCE data set will contribute to the reduction of large uncertainties in wet removal process of BC in global‐ and regional‐scale models.
Key Points
Aircraft obtained 120 vertical profiles of BC and CO over East Asia
Wet removal of BC was greater for air originating from south than north China
Removal of BC depended on amount of precipitation experienced during transport
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