An intensive measurement campaign was performed in June 2000 at the Mt. Cimone station (44°11' N-10°42' E, 2165 m asl, the highest mountain in the northern Italian Apennines) to study photochemical ...ozone production in the lower free troposphere. In general, average mixing ratios of important trace gases were not very high (121 ± 20 ppbv CO, 0.284 ± 0.220 ppbv NOx, 1.15 ± 0.8 ppbv NOy, 58 ± 9 ppbv O3), which indicates a small contribution by local pollution. Those trace gas levels are representative of continental background air, which is further supported by the analysis of VOCs (e.g.: C2H6 = (905 ± 200) pptv, C3H8 = (268 ±110) pptv, C2H2 = (201 ± 102) pptv, C5H8 = (111 ± 124) pptv, benzene = (65 ± 33) pptv). Furthermore, significant diurnal variations for a number of trace gases (O3, CO, NOx, NOy, HCHO) indicate the presence of free tropospheric airmasses at nighttime as a consequence of local catabatic winds. Average mid-day peroxy radical concentrations at Mt. Cimone are of the order of 30 pptv. At mean NO concentrations of the order of 40 pptv this gives rise to significant in situ net O3 production of 0.1-0.3 ppbv/hr. The importance of O3 production is supported by correlations between O3, CO, NOz, and HCHO, and between HCHO, CO and NOy.
Background: It is unknown whether microalbuminuria is associated with non‐alcoholic fatty liver disease (NAFLD) among patients with prediabetes and type 2 diabetes mellitus (DM). This study ...investigated the association of NAFLD with microalbuminuria among patients with prediabetes and diabetes.
Methods: We evaluated 1361 subjects who had an abnormal oral glucose tolerance test (OGTT) on routine screening. All participants were divided into two groups, prediabetes and newly diagnosed type 2 DM, and the association of NAFLD with metabolic parameters on microalbuminuria was analysed.
Results: The patients with NAFLD had higher prevalence rates of microalbuminuria (6.3% vs 19%; P= 0.001 in prediabetes, 4.5% vs 32.6%; P < 0.001 in diabetes) and also had a greater albumin‐to‐creatinine ratio (14.6 ± 52.0 µg/mg Cr vs 27.7 ± 63.9 µg/mg Cr; P= 0.051 in prediabetes, 11.4 ± 21.4 µg/mg Cr vs 44.7 ± 76.4 µg/mg Cr; P < 0.001 in diabetes) than those without NAFLD. The logistic regression analysis showed that NAFLD was associated with increased rates of microalbuminuria (odds ratio 3.66; 95% confidence interval (CI) 1.31–10.20, P= 0.013 in prediabetes, odds ratio 5.47; 95% CI 1.01–29.61, P= 0.048 in diabetes), independently of age, sex, body mass index, waist circumference, liver enzymes, lipid profiles, HbA1c, insulin resistance as estimated by homeostasis model assessment, hypertension, smoking status and the metabolic syndrome.
Conclusions: The results of our study revealed a strong relationship between microalbuminuria and NAFLD in the patients with prediabetes and newly diagnosed diabetes. Further studies are required to confirm whether NAFLD is a predictor of the development of microalbuminuria in patients with prediabetes and diabetes.
Though mucosal cysts in the paranasal sinuses (PSMCs) are common findings on radiographic images, the nature of PSMCs and risk factors for the development of PSMCs have not yet been determined. The ...aim of this study was to evaluate the characteristics of PSMCs using brain magnetic resonance (MR) imaging.
A total of 6831 subjects who underwent health checkup including brain MR imaging were included in this study. The characteristics of PSMCs, including their location, number and size, as well as the presence of obstruction of the sinus ostium and sinusitis, were analysed using brain MR images. Structured questionnaires and medical records were reviewed to evaluate the smoking status and comorbid medical conditions.
The overall prevalence of PSMCs was 7.4% and was significantly higher in females than in males. PSMCs were most commonly found in the maxillary sinus, most of which were located unilaterally as a solitary cyst. Large cysts were associated with obstruction of the sinus ostium and subsequent sinusitis. Smoking was a single important risk factor for developing PSMCs. No significant associations were found between symptoms (nasal/respiratory) and the presence of PSMCs.
The prevalence of PSMCs was 7.4% and decreased with age. Large cysts may lead to obstruction of the sinus and subsequent sinusitis. Smoking was an important risk factor for PSMCs, and the total amount of smoking correlated with cyst size. Most subjects were asymptomatic, and specific treatment was not performed.
Background:
A composite metric for the quality of glycemia from continuous glucose monitor (CGM) tracings could be useful for assisting with basic clinical interpretation of CGM data.
Methods:
We ...assembled a data set of 14-day CGM tracings from 225 insulin-treated adults with diabetes. Using a balanced incomplete block design, 330 clinicians who were highly experienced with CGM analysis and interpretation ranked the CGM tracings from best to worst quality of glycemia. We used principal component analysis and multiple regressions to develop a model to predict the clinician ranking based on seven standard metrics in an Ambulatory Glucose Profile: very low–glucose and low-glucose hypoglycemia; very high–glucose and high-glucose hyperglycemia; time in range; mean glucose; and coefficient of variation.
Results:
The analysis showed that clinician rankings depend on two components, one related to hypoglycemia that gives more weight to very low-glucose than to low-glucose and the other related to hyperglycemia that likewise gives greater weight to very high-glucose than to high-glucose. These two components should be calculated and displayed separately, but they can also be combined into a single Glycemia Risk Index (GRI) that corresponds closely to the clinician rankings of the overall quality of glycemia (r = 0.95). The GRI can be displayed graphically on a GRI Grid with the hypoglycemia component on the horizontal axis and the hyperglycemia component on the vertical axis. Diagonal lines divide the graph into five zones (quintiles) corresponding to the best (0th to 20th percentile) to worst (81st to 100th percentile) overall quality of glycemia. The GRI Grid enables users to track sequential changes within an individual over time and compare groups of individuals.
Conclusion:
The GRI is a single-number summary of the quality of glycemia. Its hypoglycemia and hyperglycemia components provide actionable scores and a graphical display (the GRI Grid) that can be used by clinicians and researchers to determine the glycemic effects of prescribed and investigational treatments.
Experiments investigating the isotopic fractionation in the formation of H2 by the photolysis of CH2O under tropospheric conditions are reported and discussed. The deuterium (D) depletion in the H2 ...produced is 500(±20)‰ with respect to the parent CH2O. We also observed that complete photolysis of CH2O under atmospheric conditions produces H2 that has virtually the same isotope ratio as that of the parent CH2O. These findings imply that there must be a very strong concomitant isotopic enrichment in the radical channel (CH2O+hν → CHO+H) as compared to the molecular channel (CH2O+hν → H2+CO) of the photolysis of CH2O in order to balance the relatively small isotopic fractionation in the competing reaction of CH2O with OH. Using a 1-box photochemistry model we calculated the isotopic fractionation factor for the radical channel to be 0.22(±0.08), which is equivalent to a 780(±80)‰ enrichment in D of the remaining CH2O. When CH2O is in photochemical steady state, the isotope ratio of the H2 produced is determined not only by the isotopic fractionation occurring during the photolytical production of H2 (αm) but also by overall fractionation for the removal processes of CH2O (αf), and is represented by the ratio of αm/αf. Applying the isotopic fractionation factors relevant to CH2O photolysis obtained in the present study to the troposphere, the ratio of αm/αf varies from ~0.8 to ~1.2 depending on the fraction of CH2O that reacts with OH and that produces H2. This range of αm/αf can render the H2 produced from the photochemical oxidation of CH4 to be enriched in D (with respect to the original CH4) by the factor of 1.2–1.3 as anticipated in the literature.
Cellular regulation by hydrogen peroxide Rhee, Sue Goo; Chang, Tong-Shin; Bae, Yun Soo ...
Journal of the American Society of Nephrology
14, Številka:
8 Suppl 3
Journal Article
Recenzirano
Odprti dostop
Substantial evidence suggests that the transient production of H(2)O(2) is an important signaling event triggered by the activation of various cell surface receptors. Understanding the intracellular ...messenger function of H(2)O(2) calls for studies of how receptor occupation elicits the production of H(2)O(2), what kinds of molecules are targeted by the produced H(2)O(2), and how H(2)O(2) is eliminated after the completion of its mission. Recent studies suggest that growth factor-induced H(2)O(2) production requires the activation of PtdIns 3-kinase. The essential role of PtdIns 3-kinase is likely to provide PI(3,4,5)P(3) that recruits and activates a guanine nucleotide exchange factor of Rac, which is required for the activation of NADPH oxidase. The targets of H(2)O(2) action include proteins that contain a reactive Cys residue. Thus, H(2)O(2) produced in response to growth factor causes inactivation of protein tyrosine phosphatases in various cells by oxidizing specifically the catalytic Cys. These results, together with other observations, indicate that the activation of a receptor tyrosine kinase per se by binding of the corresponding growth factor might not be sufficient to increase the steady-state level of protein tyrosine phosphorylation in cells. Rather, the concurrent inhibition of protein tyrosine phosphatases by H(2)O(2) might also be required. Peroxiredoxins, members of a newly discovered family of peroxidases, efficiently reduced the intracellular level of H(2)O(2) produced in the cells stimulated with various cell surface ligands. Furthermore, the activity of peroxiredoxin enzymes seems to be regulated via protein phosphorylation as in the case of many other intracellular messenger metabolizing enzymes.
This paper deals with alternative multi-functional structures by using grid-stiffened composite panel with excellent bending stiffness and lightweight characteristics. The grid-stiffened ...multi-functional structure can provide an array of available rooms for integrating multiple electronic circuitries into structure with ease. The substrate fabrication process was proposed and the grid-stiffened multi-functional structure equipped with several electronics and interfaces was built up. In order to improve the thermal conduction capability, pitch-based carbon fibers were applied to facesheet of the multi-functional structure. The spot shielding technique was also proposed to enhance the radiation shielding at the selective region sensitive to radiation, and the lightweight radiation spot shielding plate was fabricated with multi-layered laminate of CFRP and tungsten foil. The radiation shielding effectiveness of the multi-functional structure with spot shielding plate was demonstrated by proton beam irradiation test. Through the test, it was found that the radiation spot shielding plate has comparable proton-shielding performance to aluminum but more lightweight characteristics than aluminum. Grid-stiffened MFS with radiation spot shielding can be an effective measure for accommodating lots of electronics into structure, providing dramatic mass and volume savings in spacecraft design.
Hydrogen peroxide is implicated as an intracellular messenger in various cellular responses such as proliferation and differentiation. Peroxiredoxin (Prx) I is a member of the peroxiredoxin family of ...peroxidases and contains a consensus site (Thr90-Pro-Lys-Lys) for phosphorylation by cyclin-dependent kinases (CDKs). This protein has now been shown to be phosphorylated specifically on Thr90 by several CDKs, including Cdc2, in vitro. Phosphorylation of Prx I on Thr90 reduced the peroxidase activity of this protein by 80%. The phosphorylation of Prx I in HeLa cells was monitored with the use of antibodies specific for Prx I phosphorylated on Thr90. Immunoblot analysis with these antibodies of HeLa cells arrested at various stages of the cell cycle revealed that Prx I phosphorylation occurs in parallel with the activation of Cdc2; Prx I phosphorylation was thus marked during mitosis but virtually undetectable during interphase. Furthermore, when Cdc2 expression was reduced by RNA interference with cognate small interfering RNAs, Prx I phosphorylation was not observed in the cells synchronized in mitotic phase. The cytosolic location of Prx I likely prevents its interaction with activated CDKs until after the breakdown of the nuclear envelope during mitosis, when Cdc2 is the CDK that is most active. Phosphorylation of Prx I on Thr90 both in vitroand in vivo was blocked by roscovitine, an inhibitor of CDKs. These results suggest that Cdc2-mediated phosphorylation and inactivation of Prx I and the resulting intracellular accumulation of H2O2 might be important for progression of the cell cycle.
Alluvial groundwaters in the area where intensive agricultural activity takes place were geochemically investigated to evaluate factors regulating groundwater quality of alluvial aquifers. For this ...study, 55 groundwater samples were taken from the uniformly distributed irrigation wells and were classified into three distinct groups according to their geochemical characteristics. This study reveals that the groundwater quality and the geochemical characteristics of the clustered groups are consistent with the geology of the area. The samples collected from the area where a thick silt bed overlies the sand aquifer are clustered into Group II and show water quality that is only slightly affected by the contaminants originating from the land surface. However, groundwaters of this group are very high in Fe and Mn levels due to strong anoxic condition caused by the thick silt bed. In contrast, Group I shows water quality largely influenced by agricultural activities (i.e., fertilization, liming) and occurs in the area adjacent to the river where the silt bed is not observed and the sand aquifer is covered with sandy soils. Group III mostly occurs in the upgradient of Group I where a thin, silty soil covers the sand aquifer. In overall, the results show that the clustered groups closely reflect the groundwater susceptibility to the contaminants originated from the land surface. This suggests that groundwater clustering based on water chemistry could be applied to the contamination susceptibility assessment for groundwaters in the agricultural area.
The air–water exchange of gases can be substantially enhanced by wave breaking and specifically by bubble-mediated transfer. A feature of bubble-mediated transfer is the additional pressure on ...bubbles resulting from the hydrostatic forces on a submerged bubble and from surface tension and curvature. This peculiarity results in asymmetry of bubble-mediated gas transfer and equilibrium supersaturations of dissolved gases in a bubbly ocean. A second peculiarity is the finite capacity of bubbles, so that the composition of a bubble may change during the exchange. The result is that gas transfer mediated by bubbles is characterized by an altered dependence on the molecular properties of the dissolved gas compared to direct transfer across the main air–water interface. A related phenomenon for bubble plumes with a high void fraction (air volume to total volume ratio) is that the composition of the dissolved gas within the interstitial water of a plume may alter during the exchange process and only mix into the full water reservoir later. Three asymptotes are identified for gas exchange mediated by high-void-fraction bubble plumes and a semi-empirical parameterization of bubble-mediated gas transfer is devised on the basis of these asymptotes, which describes the dependence of the overall transfer velocity on plume properties and molecular properties of the gas.
These models are confronted with data from laboratory experiments. The experiments use artificial aeration with the gas source switched during each run. Measurements of the bubble distribution enable calculation of the theoretical transfer of the gases. A parameterization fits the theoretical transfer satisfactorily. Gas measurements are used to test if the actual transfer of gases is similar to the theoretical transfer. The experimental method enables separation of bubble-mediated transfer from transfer directly across the main air–water interface. The agreement between gas and bubble-derived values of transfer velocity is sufficient to generally validate the theory, but is imprecise. The results suggest that the interstitial water plays a significant role in limiting gas transfer–in particular, limiting transfer of helium–despite the fact that typical void fractions were low (<
0.1%). It should be possible to predict gas transfer velocities in the field by simulating oceanic bubble plumes sufficient to constrain that part of the transfer, but targets of 10% or 20% may be beyond reach especially for the most poorly soluble gases (for which the bubble-mediated mechanism is particularly important). These simulations require accurate bubble distributions, void fractions and a good description of the entire plume dynamics. Such simulations are particularly important for interpreting dual tracer and nitrogen/oxygen experiments in stormy conditions, where the relative transfer of different gases is a non-trivial problem.
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