Knowledge about factors regulating vasculogenesis remains limited. The cellular repressor of E1A-... more Knowledge about factors regulating vasculogenesis remains limited. The cellular repressor of E1A-stimulated gene (CREG) has been reported to be involved in maintaining cellular differentiation and endothelial homeostasis, thus we hypothesize that CREG may be a novel factor regulating vasculogenesis. By using mouse embryonic stem cells (ESC) derived embryoid body (EB) model, we confirmed expression of CREG was significantly up-regulated during EB differentiation. Overexpression of CREG in ESC led to accelerated cystic EB formation, increased endothelial differentiation and vasculogenesis, whereas knockdown of CREG produced opposite phenotypes. Moreover, we found expression of vascular endothelial growth factor (VEGF) was up-regulated and PI3K/Akt pathway was activated in CREG-overexpressing EB. Administration of VEGF neutralizing antibody or PI3K/Akt pharmacological inhibitor LY294002 blocked the vasculogenesis in CREG over-expressing EB, while supplement of VEGF rescued vasculogenesis deficiency in CREG knocked down EB. Further study by Western blot determined that PI3K/Akt was a downstream effector of VEGF. We identify CREG as a novel factor in regulating endothelial differentiation and vasculogenesis via VEGF/PI3K/Akt pathway.
To explore the molecular mechanism of brain tissue injury induced by lipopolysaccharide (LPS), we... more To explore the molecular mechanism of brain tissue injury induced by lipopolysaccharide (LPS), we studied the effects of endotoxic shock on rat brain cortex NF-kappaB and the effects of dexamethasone on these changes. Rats were randomly divided into LPS, LPS + dexamethasone, and control groups. The DNA-binding activity of NF-kappaB was observed using electrophoretic mobility shift assay (EMSA). Protein expression in nuclear extracts was studied using Western blots, and nuclear translocation was observed using immunohistochemistry. These indices were assayed at 1 h and 4 h after intravenous injection of LPS (4 mg x kg(-1)). EMSA showed significantly increased NF-kappaB DNA-binding activity in nuclear extracts from the LPS group at both 1 h and 4 h after LPS injection, compared with the control group (P < 0.01). For the LPS group, the NF-kappaB DNA-binding activity was greater at 1 h than at 4 h (P < 0.05). The expression of p65 and p50 protein in the nuclear extracts was also increased, as compared with the control group. However, the expression of p65 and p50 protein from cytosolic extracts did not show any significant change. Dexamethasone down-regulated not only NF-kappaB DNA-binding activity but also the expression of p65 protein in the nuclear extracts. From these data, we have concluded that NF-kappaB activation and nuclear translocation of NF-kappaB play a key role in the molecular mechanism of brain tissue injury in endotoxic shock. Dexamethasone may alleviate brain injury by inhibiting NF-kappaB activation.
Journal of Geophysical Research: Atmospheres, 2013
ABSTRACT [1] Limitations in the chemical characterization of tropospheric organic aerosol (OA) co... more ABSTRACT [1] Limitations in the chemical characterization of tropospheric organic aerosol (OA) continue to impede attempts to fully understand its chemical sources and sinks. To assess the role of organic nitrates in OA, we used a new thermal dissociation-laser induced fluorescence-based (TD-LIF) technique to obtain a high-time-resolution record of total aerosol organic nitrates (hereafter ΣANsaer) at the Bakersfield, CA supersite during the 2010 CalNex campaign. The TD-LIF measurements compare well with Fourier transform infrared measurements from collocated filter samples. These measurements show that ΣANs are a ubiquitous component of the OA with the –ONO2 subunit comprising on average 4.8% of the OA mass. Scaling this fraction by an estimate of the organic backbone mass yields an estimate that 17–23% of OA molecules contain nitrate functional groups. Measurements of both total ΣAN (gas + aerosol) and ΣANaer show that on average 21% of ΣANs are in the condensed phase, suggesting atmospheric organic nitrates have similar volatilities to analogous non-nitrate oxidized organic compounds. The fraction of ΣAN that is in the condensed phase increases with total OA concentration, providing direct evidence from the atmosphere that absorptive partitioning into OA has some control over the ΣAN phase partitioning. The specific molecular identity of the ΣAN is incompletely understood. Both biogenic hydrocarbons and long chain alkanes are calculated to be significant sources of low volatility nitrates in Bakersfield, and ultra performance liquid chromatography coupled to an electrospray ionization high-resolution quadrupole time-of-flight mass spectrometer measurements confirm the existence of particulate nitrooxy organosulfates derived from gas-phase oxidation of both isoprene and monoterpenes.
Black carbon (BC) and light-absorbing organic carbon (brown carbon, BrC) play key roles in warmin... more Black carbon (BC) and light-absorbing organic carbon (brown carbon, BrC) play key roles in warming the atmosphere, but the magnitude of their effects remains highly uncertain. Theoretical modelling and laboratory experiments demonstrate that coatings on BC can enhance BC's light absorption, therefore many climate models simply assume enhanced BC absorption by a factor of ∼1.5. However, recent field observations show negligible absorption enhancement, implying models may overestimate BC's warming. Here we report direct evidence of substantial field-measured BC absorption enhancement, with the magnitude strongly depending on BC coating amount. Increases in BC coating result from a combination of changing sources and photochemical aging processes. When the influence of BrC is accounted for, observationally constrained model calculations of the BC absorption enhancement can be reconciled with the observations. We conclude that the influence of coatings on BC absorption should be...
Huan jing ke xue= Huanjing kexue / [bian ji, Zhongguo ke xue yuan huan jing ke xue wei yuan hui "Huan jing ke xue" bian ji wei yuan hui.], 2006
On-line measurements of particle number size distribution were conducted during 2004-07-13 - 2004... more On-line measurements of particle number size distribution were conducted during 2004-07-13 - 2004-08-23 by using TDMPS-APS system in Beijing; in between the size distributions of particle mass and chemical compositions were measured by using MOUDI cascade impactor under three kinds of weather conditions: (1) high temperature and high relative humidity night, (2) high temperature and high relative humidity day, and (3) clear days. The results indicate that particulate matter, especially fine particle pollution becomes severe under high temperature and high relative humidity conditions, which results in low visibility (2.5km); the average concentrations of PM1.8 and PM10 are 170.68 microg/m3 and 249.35 microg/m3, respectively, PM1.8 accounts for 68% of PM10; number concentration mainly concentrates in the range of 50 - 100nm, about 2 x 10(4) - 3 x 10(4)cm(-3); rain process has a great effect on scavenging particles, especially fine particles. After the rain process PM10 is 3 times low...
Organic aerosols (OA) in the atmosphere affect Earth's energy budget by not only scattering b... more Organic aerosols (OA) in the atmosphere affect Earth's energy budget by not only scattering but also absorbing solar radiation due to the presence of the so-called "brown carbon" (BrC) component. However, the absorptivities of OA are not or poorly represented in current climate and chemical transport models. In this study, we provide a method to constrain the BrC absorptivity at the emission inventory level using recent laboratory and field observations. We review available measurements of the light-absorbing primary OA (POA), and quantify the wavelength-dependent imaginary refractive indices (kOA, the fundamental optical parameter determining the particle's absorptivity) and their uncertainties of the bulk POA emitted from biomass/biofuel, lignite, propane, and oil combustion sources. In particular, we parameterize the kOA of biomass/biofuel combustion sources as a function of the black carbon (BC)-to-OA ratio, indicating that the absorptive properties of POA depe...
Objective—Increased level of plasma advanced oxidation protein products (AOPPs) has been found in... more Objective—Increased level of plasma advanced oxidation protein products (AOPPs) has been found in patients with uremia and nonuremic subjects with coronary artery disease. This study was conducted to test the hypothesis that AOPPs play a causal role in atherosclerosis. Methods and Results—Hypercholesterolemic (0.5% wt/wt diet) or normal rabbits received either repeated intravenous injections of AOPPs modified rabbit serum albumin (AOPPs-RSA)
ABSTRACT Atmospheric particulate matter plays an important role in the Earth's radiative ... more ABSTRACT Atmospheric particulate matter plays an important role in the Earth's radiative balance. Over the past two decades, it has been established that a portion of particulate matter, black carbon, absorbs significant amounts of light and exerts a warming effect rivalling that of anthropogenic carbon dioxide(1,2). Most climate models treat black carbon as the sole light-absorbing carbonaceous particulate. However, some organic aerosols, dubbed brown carbon and mainly associated with biomass burning emissions(3-6), also absorbs light(7). Unlike black carbon, whose light absorption properties are well understood(8), brown carbon comprises a wide range of poorly characterized compounds that exhibit highly variable absorptivities, with reported values spanning two orders of magnitude(3-6,9,10). Here we present smog chamber experiments to characterize the effective absorptivity of organic aerosol from biomass burning under a range of conditions. We show that brown carbon in emissions from biomass burning is associated mostly with organic compounds of extremely low volatility(11). In addition, we find that the effective absorptivity of organic aerosol in biomass burning emissions can be parameterized as a function of the ratio of black carbon to organic aerosol, indicating that aerosol absorptivity depends largely on burn conditions, not fuel type. We conclude that brown carbon from biomass burning can be an important factor in aerosol radiative forcing.
ABSTRACT In this paper, we study the joint price and power allocation in spectrum sharing macro-f... more ABSTRACT In this paper, we study the joint price and power allocation in spectrum sharing macro-femtocell networks. The proposed game theoretic framework is based on bi-level Stackelberg game where macro base station (MBS) works as a leader and underlaid femto base stations (FBSs) work as followers. MBS has fixed data rate and imposes interference price on FBSs for maintaining its data rate and earns revenue while FBSs jointly adjust their power for maximizing their data rates and utility functions. Since the interference from FBSs to macro user equipment is kept under a given threshold and FBSs compete against each other for power allocation, there is a need to determine a power allocation strategy which converges to Stackelberg equilibrium. We consider two cases for MBS power allocation, i.e., fixed and dynamic power. MBS can adjust its power in case of dynamic power allocation according to its minimum data rate requirement and number of FBSs willing to share the spectrum. For both cases we consider uniform and nonuniform pricing where MBS charges same price to all FBSs for uniform pricing and different price to each FBS for non-uniform pricing according to its induced interference. We obtain unique closed form solution for each case if the co-interference at FBSs is assumed fixed. And an iterative algorithm which converges rapidly is also proposed to take into account the effect of co-tier interference on interference price and power allocation strategy. The results are explained with numerical simulation examples which validate the effectiveness of our proposed solutions.
ABSTRACT In this paper we study the joint price and power allocation for interference management ... more ABSTRACT In this paper we study the joint price and power allocation for interference management in macro- femto spectrum sharing network based on the Stackelberg game. In our model, the macro base station (MBS) works as leader and overlaid femto base stations (FBSs) as followers. The MBS allocates its power and interference price to the FBSs to guarantee its user's minimum rate requirement and reap the revenue from the femto network. Based on this price, FBSs calculates their power in distributed way. The game is formulated for joint utility maximization of both types of players. We consider the two cases of fixed and dynamic MBS power and propose uniform price for all FBSs. In this game model, first of all the number of players (FBSs) is calculated that can participate in the game against different macro user rate requirement and then price and power are determined. We propose unique closed form solution to the both cases based on convex optimization which always guarantee the convergence. The numerical results validate the effectiveness of our proposed solutions.
Laboratory studies have established a number of chemical pathways by which nitrogen oxides (NO(x)... more Laboratory studies have established a number of chemical pathways by which nitrogen oxides (NO(x)) affect atmospheric organic aerosol (OA) production. However, these effects have not been directly observed in ambient OA. We report measurements of particulate organic nitrates in Bakersfield, California, the nighttime formation of which increases with NO(x) and is suppressed by high concentrations of organic molecules that rapidly react with nitrate radical (NO(3))--evidence that multigenerational chemistry is responsible for organic nitrate aerosol production. This class of molecules represents about a third of the nighttime increase in OA, suggesting that most nighttime secondary OA is due to the NO(3) product of anthropogenic NO(x) emissions. Consequently, reductions in NO(x) emissions should reduce the concentration of organic aerosol in Bakersfield and the surrounding region.
Knowledge about factors regulating vasculogenesis remains limited. The cellular repressor of E1A-... more Knowledge about factors regulating vasculogenesis remains limited. The cellular repressor of E1A-stimulated gene (CREG) has been reported to be involved in maintaining cellular differentiation and endothelial homeostasis, thus we hypothesize that CREG may be a novel factor regulating vasculogenesis. By using mouse embryonic stem cells (ESC) derived embryoid body (EB) model, we confirmed expression of CREG was significantly up-regulated during EB differentiation. Overexpression of CREG in ESC led to accelerated cystic EB formation, increased endothelial differentiation and vasculogenesis, whereas knockdown of CREG produced opposite phenotypes. Moreover, we found expression of vascular endothelial growth factor (VEGF) was up-regulated and PI3K/Akt pathway was activated in CREG-overexpressing EB. Administration of VEGF neutralizing antibody or PI3K/Akt pharmacological inhibitor LY294002 blocked the vasculogenesis in CREG over-expressing EB, while supplement of VEGF rescued vasculogenesis deficiency in CREG knocked down EB. Further study by Western blot determined that PI3K/Akt was a downstream effector of VEGF. We identify CREG as a novel factor in regulating endothelial differentiation and vasculogenesis via VEGF/PI3K/Akt pathway.
To explore the molecular mechanism of brain tissue injury induced by lipopolysaccharide (LPS), we... more To explore the molecular mechanism of brain tissue injury induced by lipopolysaccharide (LPS), we studied the effects of endotoxic shock on rat brain cortex NF-kappaB and the effects of dexamethasone on these changes. Rats were randomly divided into LPS, LPS + dexamethasone, and control groups. The DNA-binding activity of NF-kappaB was observed using electrophoretic mobility shift assay (EMSA). Protein expression in nuclear extracts was studied using Western blots, and nuclear translocation was observed using immunohistochemistry. These indices were assayed at 1 h and 4 h after intravenous injection of LPS (4 mg x kg(-1)). EMSA showed significantly increased NF-kappaB DNA-binding activity in nuclear extracts from the LPS group at both 1 h and 4 h after LPS injection, compared with the control group (P < 0.01). For the LPS group, the NF-kappaB DNA-binding activity was greater at 1 h than at 4 h (P < 0.05). The expression of p65 and p50 protein in the nuclear extracts was also increased, as compared with the control group. However, the expression of p65 and p50 protein from cytosolic extracts did not show any significant change. Dexamethasone down-regulated not only NF-kappaB DNA-binding activity but also the expression of p65 protein in the nuclear extracts. From these data, we have concluded that NF-kappaB activation and nuclear translocation of NF-kappaB play a key role in the molecular mechanism of brain tissue injury in endotoxic shock. Dexamethasone may alleviate brain injury by inhibiting NF-kappaB activation.
Journal of Geophysical Research: Atmospheres, 2013
ABSTRACT [1] Limitations in the chemical characterization of tropospheric organic aerosol (OA) co... more ABSTRACT [1] Limitations in the chemical characterization of tropospheric organic aerosol (OA) continue to impede attempts to fully understand its chemical sources and sinks. To assess the role of organic nitrates in OA, we used a new thermal dissociation-laser induced fluorescence-based (TD-LIF) technique to obtain a high-time-resolution record of total aerosol organic nitrates (hereafter ΣANsaer) at the Bakersfield, CA supersite during the 2010 CalNex campaign. The TD-LIF measurements compare well with Fourier transform infrared measurements from collocated filter samples. These measurements show that ΣANs are a ubiquitous component of the OA with the –ONO2 subunit comprising on average 4.8% of the OA mass. Scaling this fraction by an estimate of the organic backbone mass yields an estimate that 17–23% of OA molecules contain nitrate functional groups. Measurements of both total ΣAN (gas + aerosol) and ΣANaer show that on average 21% of ΣANs are in the condensed phase, suggesting atmospheric organic nitrates have similar volatilities to analogous non-nitrate oxidized organic compounds. The fraction of ΣAN that is in the condensed phase increases with total OA concentration, providing direct evidence from the atmosphere that absorptive partitioning into OA has some control over the ΣAN phase partitioning. The specific molecular identity of the ΣAN is incompletely understood. Both biogenic hydrocarbons and long chain alkanes are calculated to be significant sources of low volatility nitrates in Bakersfield, and ultra performance liquid chromatography coupled to an electrospray ionization high-resolution quadrupole time-of-flight mass spectrometer measurements confirm the existence of particulate nitrooxy organosulfates derived from gas-phase oxidation of both isoprene and monoterpenes.
Black carbon (BC) and light-absorbing organic carbon (brown carbon, BrC) play key roles in warmin... more Black carbon (BC) and light-absorbing organic carbon (brown carbon, BrC) play key roles in warming the atmosphere, but the magnitude of their effects remains highly uncertain. Theoretical modelling and laboratory experiments demonstrate that coatings on BC can enhance BC's light absorption, therefore many climate models simply assume enhanced BC absorption by a factor of ∼1.5. However, recent field observations show negligible absorption enhancement, implying models may overestimate BC's warming. Here we report direct evidence of substantial field-measured BC absorption enhancement, with the magnitude strongly depending on BC coating amount. Increases in BC coating result from a combination of changing sources and photochemical aging processes. When the influence of BrC is accounted for, observationally constrained model calculations of the BC absorption enhancement can be reconciled with the observations. We conclude that the influence of coatings on BC absorption should be...
Huan jing ke xue= Huanjing kexue / [bian ji, Zhongguo ke xue yuan huan jing ke xue wei yuan hui "Huan jing ke xue" bian ji wei yuan hui.], 2006
On-line measurements of particle number size distribution were conducted during 2004-07-13 - 2004... more On-line measurements of particle number size distribution were conducted during 2004-07-13 - 2004-08-23 by using TDMPS-APS system in Beijing; in between the size distributions of particle mass and chemical compositions were measured by using MOUDI cascade impactor under three kinds of weather conditions: (1) high temperature and high relative humidity night, (2) high temperature and high relative humidity day, and (3) clear days. The results indicate that particulate matter, especially fine particle pollution becomes severe under high temperature and high relative humidity conditions, which results in low visibility (2.5km); the average concentrations of PM1.8 and PM10 are 170.68 microg/m3 and 249.35 microg/m3, respectively, PM1.8 accounts for 68% of PM10; number concentration mainly concentrates in the range of 50 - 100nm, about 2 x 10(4) - 3 x 10(4)cm(-3); rain process has a great effect on scavenging particles, especially fine particles. After the rain process PM10 is 3 times low...
Organic aerosols (OA) in the atmosphere affect Earth's energy budget by not only scattering b... more Organic aerosols (OA) in the atmosphere affect Earth's energy budget by not only scattering but also absorbing solar radiation due to the presence of the so-called "brown carbon" (BrC) component. However, the absorptivities of OA are not or poorly represented in current climate and chemical transport models. In this study, we provide a method to constrain the BrC absorptivity at the emission inventory level using recent laboratory and field observations. We review available measurements of the light-absorbing primary OA (POA), and quantify the wavelength-dependent imaginary refractive indices (kOA, the fundamental optical parameter determining the particle's absorptivity) and their uncertainties of the bulk POA emitted from biomass/biofuel, lignite, propane, and oil combustion sources. In particular, we parameterize the kOA of biomass/biofuel combustion sources as a function of the black carbon (BC)-to-OA ratio, indicating that the absorptive properties of POA depe...
Objective—Increased level of plasma advanced oxidation protein products (AOPPs) has been found in... more Objective—Increased level of plasma advanced oxidation protein products (AOPPs) has been found in patients with uremia and nonuremic subjects with coronary artery disease. This study was conducted to test the hypothesis that AOPPs play a causal role in atherosclerosis. Methods and Results—Hypercholesterolemic (0.5% wt/wt diet) or normal rabbits received either repeated intravenous injections of AOPPs modified rabbit serum albumin (AOPPs-RSA)
ABSTRACT Atmospheric particulate matter plays an important role in the Earth's radiative ... more ABSTRACT Atmospheric particulate matter plays an important role in the Earth's radiative balance. Over the past two decades, it has been established that a portion of particulate matter, black carbon, absorbs significant amounts of light and exerts a warming effect rivalling that of anthropogenic carbon dioxide(1,2). Most climate models treat black carbon as the sole light-absorbing carbonaceous particulate. However, some organic aerosols, dubbed brown carbon and mainly associated with biomass burning emissions(3-6), also absorbs light(7). Unlike black carbon, whose light absorption properties are well understood(8), brown carbon comprises a wide range of poorly characterized compounds that exhibit highly variable absorptivities, with reported values spanning two orders of magnitude(3-6,9,10). Here we present smog chamber experiments to characterize the effective absorptivity of organic aerosol from biomass burning under a range of conditions. We show that brown carbon in emissions from biomass burning is associated mostly with organic compounds of extremely low volatility(11). In addition, we find that the effective absorptivity of organic aerosol in biomass burning emissions can be parameterized as a function of the ratio of black carbon to organic aerosol, indicating that aerosol absorptivity depends largely on burn conditions, not fuel type. We conclude that brown carbon from biomass burning can be an important factor in aerosol radiative forcing.
ABSTRACT In this paper, we study the joint price and power allocation in spectrum sharing macro-f... more ABSTRACT In this paper, we study the joint price and power allocation in spectrum sharing macro-femtocell networks. The proposed game theoretic framework is based on bi-level Stackelberg game where macro base station (MBS) works as a leader and underlaid femto base stations (FBSs) work as followers. MBS has fixed data rate and imposes interference price on FBSs for maintaining its data rate and earns revenue while FBSs jointly adjust their power for maximizing their data rates and utility functions. Since the interference from FBSs to macro user equipment is kept under a given threshold and FBSs compete against each other for power allocation, there is a need to determine a power allocation strategy which converges to Stackelberg equilibrium. We consider two cases for MBS power allocation, i.e., fixed and dynamic power. MBS can adjust its power in case of dynamic power allocation according to its minimum data rate requirement and number of FBSs willing to share the spectrum. For both cases we consider uniform and nonuniform pricing where MBS charges same price to all FBSs for uniform pricing and different price to each FBS for non-uniform pricing according to its induced interference. We obtain unique closed form solution for each case if the co-interference at FBSs is assumed fixed. And an iterative algorithm which converges rapidly is also proposed to take into account the effect of co-tier interference on interference price and power allocation strategy. The results are explained with numerical simulation examples which validate the effectiveness of our proposed solutions.
ABSTRACT In this paper we study the joint price and power allocation for interference management ... more ABSTRACT In this paper we study the joint price and power allocation for interference management in macro- femto spectrum sharing network based on the Stackelberg game. In our model, the macro base station (MBS) works as leader and overlaid femto base stations (FBSs) as followers. The MBS allocates its power and interference price to the FBSs to guarantee its user's minimum rate requirement and reap the revenue from the femto network. Based on this price, FBSs calculates their power in distributed way. The game is formulated for joint utility maximization of both types of players. We consider the two cases of fixed and dynamic MBS power and propose uniform price for all FBSs. In this game model, first of all the number of players (FBSs) is calculated that can participate in the game against different macro user rate requirement and then price and power are determined. We propose unique closed form solution to the both cases based on convex optimization which always guarantee the convergence. The numerical results validate the effectiveness of our proposed solutions.
Laboratory studies have established a number of chemical pathways by which nitrogen oxides (NO(x)... more Laboratory studies have established a number of chemical pathways by which nitrogen oxides (NO(x)) affect atmospheric organic aerosol (OA) production. However, these effects have not been directly observed in ambient OA. We report measurements of particulate organic nitrates in Bakersfield, California, the nighttime formation of which increases with NO(x) and is suppressed by high concentrations of organic molecules that rapidly react with nitrate radical (NO(3))--evidence that multigenerational chemistry is responsible for organic nitrate aerosol production. This class of molecules represents about a third of the nighttime increase in OA, suggesting that most nighttime secondary OA is due to the NO(3) product of anthropogenic NO(x) emissions. Consequently, reductions in NO(x) emissions should reduce the concentration of organic aerosol in Bakersfield and the surrounding region.
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