Importance Of Different Pathways Research Articles

Dosing the Coast: Leaking Sewage Infrastructure Delivers Large Annual Doses and Dynamic Mixtures of Pharmaceuticals to Urban Rivers.

Pharmaceuticals are commonly detected at low concentrations in surface waters, where they disrupt biological and ecological processes. Despite their ubiquity, the annual mass of pharmaceuticals exported from watersheds is rarely quantified. We used liquid chromatography-mass spectroscopy to screen for 92 pharmaceuticals in weekly samples from an urban stream network in Baltimore, MD, USA, that lacks wastewater treatment effluents. Across the network, we detected 37 unique compounds, with higher concentrations and more compounds in streams with higher population densities. We also used concentrations and stream discharge to calculate annual pharmaceutical loads at the watershed outlet, which range from less than 1 kg to ∼15 kg and are equivalent to tens of thousands of human doses. By calculating annual watershed mass balances for eight compounds, we show that ∼0.05 to ∼42% of the pharmaceuticals consumed by humans in this watershed are released to surface waters, with the importance of different pathways (leaking sewage vs treated wastewater effluent) differing among compounds. These results demonstrate the importance of developing, maintaining, and improving sewage infrastructure to protect water resources from pharmaceutical contamination.

Isotopic constraints on atmospheric sulfate formation pathways in the Mt. Everest region, southern Tibetan Plateau

Abstract. As an important atmosphere constituent, sulfate aerosols exert profound impacts on climate, the ecological environment, and human health. The Tibetan Plateau (TP), identified as the “Third Pole”, contains the largest land ice masses outside the poles and has attracted widespread attention for its environment and climatic change. However, the mechanisms of sulfate formation in this specific region still remain poorly characterized. An oxygen-17 anomaly (Δ17O) has been used as a probe to constrain the relative importance of different pathways leading to sulfate formation. Here, we report the Δ17O values in atmospheric sulfate collected at a remote site in the Mt. Everest region to decipher the possible formation mechanisms of sulfate in such a pristine environment. Throughout the sampling campaign (April–September 2018), the Δ17O in non-dust sulfate show an average of 1.7 ‰±0.5 ‰, which is higher than most existing data on modern atmospheric sulfate. The seasonality of Δ17O in non-dust sulfate exhibits high values in the pre-monsoon and low values in the monsoon, opposite to the seasonality in Δ17O for both sulfate and nitrate (i.e., minima in the warm season and maxima in the cold season) observed from diverse geographic sites. This high Δ17O in non-dust sulfate found in this region clearly indicates the important role of the S(IV)+O3 pathway in atmospheric sulfate formation promoted by conditions of high cloud water pH. Overall, our study provides an observational constraint on atmospheric acidity in altering sulfate formation pathways, particularly in dust-rich environments, and such identification of key processes provides an important basis for a better understanding of the sulfur cycle in the TP.

Food security in rural Burkina Faso: the importance of consumption of own-farm sourced food versus purchased food

BackgroundThe number of undernourished people and the risk of micro-nutrient deficiency remain high in sub-Saharan Africa (SSA). Decades of policy designed to reverse the trends of food insecurity have illustrated that the causal pathways of intervention to end-point outcomes, such as nutrition, are not necessarily straightforward. Utilising proxies for dimensions of food security, this study investigates the relative importance of different pathways to food security in two subtly contrasting communities in the Sahelian and Sudanian Savanna zones of Burkina Faso.ResultsIn Yatenga province, approximately 31% of households were classified as ‘severely food insecure’ in the ‘lean’ period. In contrast, over 84% of households sampled in Seno province were classified as being ‘severely food insecure’ in the ‘lean’ period. There were statistically significant associations between food security indicators and off-farm income, farm income and production diversity. The source of income had significantly different associations with diet diversity in the two provinces. In Yatenga province, higher gross farm income in the absence of off-farm income was predicted to result in more diverse diets; in Seno province, however, gross farm income was only predicted to result in more diverse diets when households are also earning off-farm income.ConclusionsOur analysis shows that households were most differentiated by income generating pathways to food security in the ‘lean’ period. This finding should not detract from the essential role played by home-produced foods in improving food security. Rather, market-orientated agriculture and production for home consumption, as shown by households in this study, can be combined as part of a more resilient livelihood strategy. Policy needs to be targeted towards agro-ecological conditions, as well as socioeconomic factors in order to facilitate improved on-farm income, farm resilience and off-farm employment opportunities.

Managing invasions by terrestrial alien plants in Ireland: challenges and opportunities

The successful management of plant invasions is a global concern, given the large ecological and economic impacts of many introduced plant species, which may be compounded by interactions with other environmental and socio-economic changes. With the aim of identifying the challenges and opportunities associated with the management of terrestrial plant invasions in Ireland, in the light of international obligations, we review some of the most important initiatives that have been conducted to manage current invasive alien plants and the principles that should guide their management and the restoration of invaded communities. While the focus of most management practices has been based on the application of herbicide treatments and/or mechanical removal, alternative approaches may be needed in the future due to general environmental or site-related concerns. The likelihood of the widespread and successful eradication of the most significant plant invaders is, however, unlikely and more focus needs to be on a prioritised approach that targets areas where they have the greatest impact. Our ability to do this is, however, limited due to a poor understanding of the long-term impacts of plant invasions and the effectiveness of many control measures that fail to recognise species- and habitat-specific factors. An improved understanding of how the relative importance of different pathways of introduction will change in the future is also needed, including the volumes of seed traded on the internet. A range of citizen science initiatives have been promoted to raise awareness of plant invasions, with the aim of reducing the demand for ornamental species and the unintentional spread of existing invaders. These will be important for the early detection and eradication of new introductions as well as limiting the spread of existing invaders. However, the effective control of existing plant invaders requires an all-island coordinated approach supported by appropriate resources and scientific expertise.

Managing invasions by terrestrial alien plants in Ireland: challenges and opportunities

The successful management of plant invasions is a global concern, given the large ecological and economic impacts of many introduced plant species, which may be compounded by interactions with other environmental and socio-economic changes. With the aim of identifying the challenges and opportunities associated with the management of terrestrial plant invasions in Ireland, in the light of international obligations, we review some of the most important initiatives that have been conducted to manage current invasive alien plants and the principles that should guide their management and the restoration of invaded communities. While the focus of most management practices has been based on the application of herbicide treatments and/or mechanical removal, alternative approaches may be needed in the future due to general environmental or site-related concerns. The likelihood of the widespread and successful eradication of the most significant plant invaders is, however, unlikely and more focus needs to be on a prioritised approach that targets areas where they have the greatest impact. Our ability to do this is, however, limited due to a poor understanding of the long-term impacts of plant invasions and the effectiveness of many control measures that fail to recognise species- and habitat-specific factors. An improved understanding of how the relative importance of different pathways of introduction will change in the future is also needed, including the volumes of seed traded on the internet. A range of citizen science initiatives have been promoted to raise awareness of plant invasions, with the aim of reducing the demand for ornamental species and the unintentional spread of existing invaders. These will be important for the early detection and eradication of new introductions as well as limiting the spread of existing invaders. However, the effective control of existing plant invaders requires an all-island coordinated approach supported by appropriate resources and scientific expertise.

Modeling the Toxicokinetics of Multiple Metals in the Oyster Crassostrea hongkongensis in a Dynamic Estuarine Environment.

Metal contamination is a major problem in many estuaries. Toxicokinetic models are useful tools for predicting metal accumulation in estuarine organisms and managing the associated ecological risks. However, obtaining toxicokinetic parameter values with sufficient predictive power is challenging for dynamic estuarine waters. In this study, we determined the toxicokinetics of multiple metals in the oyster Crassostrea hongkongensis in a dynamic estuary polluted by metals using a 48 day transplant experiment. During the experiment, metal concentrations in oysters, water, and suspended particles were intensively monitored at 3 day intervals. The toxicokinetic parameters were then estimated using the Markov chain Monte Carlo (MCMC) method. The calibrated model was capable of successfully simulating the time-course of metal bioaccumulation in oysters and was further validated by predicting the bioaccumulation at another site in the estuary. Furthermore, the model was used to assess the relative importance of different pathways in metal bioaccumulation. With the MCMC method, distributions instead of single values were assigned to model parameters. This method makes the model predictions probabilistic with clearly defined uncertainties, and they are thus particularly useful for the risk assessment of metals in aquatic systems.

Reaction of O(3P) with C3H6: Yield of the Reaction Products as a Function of Temperature.

Reaction of oxygen atoms with propene is an important step in combustion processes particularly affecting the profiles of intermediate species and flame speed. The relative importance of different pathways of this multichannel reaction at different temperatures represents significant theoretical interest and is essential for modeling combustion systems. In the present work, we report the first experimental investigation of the products of the O(3P) + C3H6 reaction over an extended temperature range (298-905 K). By using a low pressure flow reactor combined with a quadrupole mass spectrometer, the yields of the five reaction products, H atom, CH3, C2H5, CH2O and OH were determined as a function of temperature between 298 and 905 K: 0.0064 × (T/298)2.74 exp(765/T), 1.41 × (T/298)-1.0 exp(-335/T), 0.92 × (T/298)-1.41 exp(-381/T), 0.17 × (T/298)0.165 exp(-36/T), and 0.0034 × (T/298)2.34 exp(788/T), respectively (corresponding to the variation of the respective yields between 298 and 905 K in the ranges 0.08-0.31, 0.46-0.32, 0.26-0.12, 0.15-0.19, and 0.05-011), independent of pressure in the range 1-8 Torr of helium. For the yields of the minor reaction products, H2 and CH3CHO the upper limits were determined as 0.2 and 0.05, respectively. These results are compared with the experimental data and theoretical calculations available in the literature.

Reaction of O(3P) with C2H4: Yield of the Reaction Products as a Function of Temperature.

Reaction of oxygen atoms with ethylene is an important step in the combustion process particularly affecting the profiles of intermediate species and flame speed. Currently, the relative importance of different pathways of this multichannel reaction at different temperatures is not fully established and determination of the branching ratios for different reaction channels as a function of temperature remains essential for modeling combustion systems. In the present work, the products of the O(3P) + C2H4 reaction have been studied over an extended temperature range (297-900 K) using a low pressure flow reactor (1-8 Torr) combined with a quadrupole mass spectrometer. The yields of the three main reaction products, H atom, CH3 radical, and CH2O, were determined to be 0.31 ± 0.05, 0.53 ± 0.09, and 0.17 ± 0.03, respectively, independent of pressure and temperature under experimental conditions of the study. For the yields of the minor reaction products, H2 and CH4, the upper limits were determined as 0.05 and 0.02, respectively. These results are compared with the experimental data and theoretical calculations available in the literature.

Postsecondary Student Persistence and Pathways: Evidence From the YITS-A in Canada

The Youth in Transition Survey is used to follow the postsecondary education (PSE) pathways and outcomes of Canadian youth over the mid 2000s. Students starting at community colleges and four year universities are analyzed separately. First program outcomes are reported, showing the proportions of students who leave their first programs but remain in PSE by switching/transferring to other programs, institutions, or levels. Multinomial regression estimates correlates of students’ first program switching and leaving decisions. Five year graduation rates are calculated to show the importance of different pathways (across programs, institutions, and levels) to earning a PSE credential; in the aggregate and for subgroups of students. Transfers constitute important but not terribly large pathways for Canadian students to adjust their PSE and obtain PSE credentials. We calculate the resulting extent to which institution specific measures of persistence, PSE leaving, and graduation rates misstate the rates experienced by students. Compared to American students, university and community college starters in Canada have higher persistence and graduation rates and lower transfer rates across institutions. For community college starters, much of the difference is due to the relative lack of well defined pathways from community colleges to universities in Canada. We find that students with more family resources are better able to transfer across programs or institutions in order to obtain a PSE credential.

The effects of apolipoprotein B depletion on HDL subspecies composition and function

HDL cholesterol (HDL-C) efflux function may be a more robust biomarker of coronary artery disease risk than HDL-C. To study HDL function, apoB-containing lipoproteins are precipitated from serum. Whether apoB precipitation affects HDL subspecies composition and function has not been thoroughly investigated. We studied the effects of four common apoB precipitation methods [polyethylene glycol (PEG), dextran sulfate/magnesium chloride (MgCl2), heparin sodium/manganese chloride (MnCl2), and LipoSep immunoprecipitation (IP)] on HDL subspecies composition, apolipoproteins, and function (cholesterol efflux and reduction of LDL oxidation). PEG dramatically shifted the size distribution of HDL and apolipoproteins (assessed by two independent methods), while leaving substantial amounts of reagent in the sample. PEG also changed the distribution of cholesterol efflux and LDL oxidation across size fractions, but not overall efflux across the HDL range. Dextran sulfate/MgCl2, heparin sodium/MnCl2, and LipoSep IP did not change the size distribution of HDL subspecies, but altered the quantity of a subset of apolipoproteins. Thus, each of the apoB precipitation methods affected HDL composition and/or size distribution. We conclude that careful evaluation is needed when selecting apoB depletion methods for existing and future bioassays of HDL function.

An Approach to Cluster EU Member States into Groups According to Pathways of Salmonella in the Farm‐to‐Consumption Chain for Pork Products

The aim of the project as the cluster analysis was to in part to develop a generic structured quantitative microbiological risk assessment (QMRA) model of human salmonellosis due to pork consumption in EU member states (MSs), and the objective of the cluster analysis was to group the EU MSs according to the relative contribution of different pathways of Salmonella in the farm-to-consumption chain of pork products. In the development of the model, by selecting a case study MS from each cluster the model was developed to represent different aspects of pig production, pork production, and consumption of pork products across EU states. The objective of the cluster analysis was to aggregate MSs into groups of countries with similar importance of different pathways of Salmonella in the farm-to-consumption chain using available, and where possible, universal register data related to the pork production and consumption in each country. Based on MS-specific information about distribution of (i) small and large farms, (ii) small and large slaughterhouses, (iii) amount of pork meat consumed, and (iv) amount of sausages consumed we used nonhierarchical and hierarchical cluster analysis to group the MSs. The cluster solutions were validated internally using statistic measures and externally by comparing the clustered MSs with an estimated human incidence of salmonellosis due to pork products in the MSs. Finally, each cluster was characterized qualitatively using the centroids of the clusters.

On-the-fly Neutron Tomography of Water Transport into Lupine Roots

Measurement and visualization of water flow in soil and roots is essential for understanding of how roots take up water from soils. Such information would allow for the optimization of irrigation practices and for the identification of the optimal traits for the capture of water, in particular when water is scarce. However, measuring water flow in roots growing in soil is challenging. The previous 2D experiments (Zarebanadkouki et al., 2012) have not been sufficient for understanding the water transport across the root and therefore we employed an on-the-fly tomography technique with temporal resolution of three minutes. In this paper, we show that the series of on-the-fly neutron tomographic experiments performed on the same sample allow for monitoring the three-dimensional spatial distribution of D2O across the root tissue. The obtained data will allow us to calculate the convective and diffusive transport properties across root tissue and to estimate the relative importance of different pathways of water across the root tissue.

Using muscle gene expression to estimate triacylglyceride deposition, and relative contributions of fatty acid synthesis and fatty acid import in intramuscular fat in cattle

Intramuscular fat content (IMF%) in cattle influences the value of individual animals, especially for higher marbling markets. IMF is triacylglyceride (TAG) in lipid droplets in the intramuscular adipocytes. However, there are many different pathways from feed intake to the final common process of TAG synthesis and storage as IMF. To evaluate the relative importance of different pathways we compared changes in the expression of genes encoding proteins involved in the TAG and fatty acid (FA) synthesis pathways in the longissimus muscle of Piedmontese × Hereford (P×H) and Wagyu × Hereford (W×H) crosses. Based on these changes we have estimated the relative contributions of FA synthesised de novo in the intramuscular adipocyte and the uptake of circulating FA (both free and from TAG), from the diet or synthesised de novo in other tissues, to TAG deposition as IMF. We have analysed the impact of different developmental times and different diets on these processes. Increased de novo FA synthesis in intramuscular adipocytes appeared to contribute more than increased FA uptake from circulation to the additional TAG deposition in W×H compared with P×H cattle between 12 and 25 months (forage diet). Changing diet from forage to concentrate appeared to increase the importance of FA uptake from circulation relative to de novo FA synthesis for TAG synthesis in intramuscular adipocytes. These results are consistent with the literature based on analysis of lipid composition. Gene expression appears to provide a simple assay for identification of the source of FA for the deposition of IMF.

580: A pathway analysis of imprinted genes in developing placentae

genes in developing placentae Jennifer King, Kai Wang, Huaiyu Mi, Nicole Bender, Rachel Steward, Sue Ingles, Joseph Ouzounian, Melissa Wilson University of Southern California, Department of Obstetrics and Gynecology, Los Angeles, CA, University of Southern California, Department of Psychiatry and The Behavioral Sciences, Los Angeles, CA, University of Southern California, Department of Preventive Medicine, Los Angeles, CA OBJECTIVE: Genomic imprinting has been demonstrated to be integral to fetal development and placentation. The majority of studies on imprinted gene expression in humans have involved term placentas, while placental imprinting is known to be a dynamic process, which evolves during human pregnancy. For these reasons, the distinct imprinted gene expression profile displayed in the early human placenta remains largely unknown. Our objective was to investigate the pattern of imprinted gene expression across first and early second trimester placental development. STUDY DESIGN: We sequenced complementary cDNA from placental villi obtained at 7, 8, 9, and 15 weeks gestation using massively parallel next-generation sequencing (RNA-seq). We used the PANTHER classification system (http://www.pantherdb.org/about.jsp) to evaluate imprinted gene expression at each gestational age in reference to the human genome. We performed a pathway analysis to determine important processes at each time point that differ from the human genome using the Wilcoxon Rank Sum test. We did not use a Bonferroni correction due to the exploratory nature of the analysis. We report the top 15 pathways for each gestational age. RESULTS: Table includes top 15 pathways for each gestational age, none of which are statistically significant after Bonferroni correction. CONCLUSION: Similarities between global gene expression pathways and imprinted gene pathways speak to the importance of imprinted genes in the developing placenta. Imprinted genes have variable expression in early placental development. The top pathway for gestational ages of 8 and 9 weeks appear remarkably similar. At 15 weeks, the molecular pathways of the imprinted genes are notably different compared to earlier gestational age. These observations may reflect changes in imprinted gene expression that occur with changes in oxygen pressure or may be a result of small sample size. Larger studies are required to differentiate. 581 A pathway analysis of the developing placentome Jennifer King, Kai Wang, Huaiyu Mi, Ian Tilley, Rachel Steward, Sue Ingles, Joseph Ouzounian, Melissa Wilson University of Southern California, Department of Obstetrics and Gynecology, Los Angeles, CA, University of Southern California, Department of Psychiatry and The Behavioral Sciences, Los Angeles, CA, University of Southern California, Department of Preventive Medicine, Los Angeles, CA OBJECTIVE: The creation of a suitable intrauterine environment for fetal development is dependent on the proper functioning of placental chorionic villi. Chorionic villi require well-coordinated expression of several transcription factors, cytokines and their receptors, growth factors, and cell cycle regulators. Disruption of the expression of these regulatory factors may lead to placental growth and development disorders. However, gene expression levels across gestatational age have not been fully delineated. Our objective was to investigate the pattern of global gene expression across first and early second trimester placental development. STUDY DESIGN: In the present investigation, we sequenced complementary cDNA from placenta villi obtained at 7, 8, 9, and 15 weeks gestation, using massively parallel next-generation sequencing (RNAseq). We used the PANTHER classification system (http://www.pantherdb.org/about.jsp) to evaluate global gene expression at each gestational age in reference to the human genome. We performed a pathway analysis to determine important processes at each time point that differ from the human genome using the Wilcoxon Rank Sum test with a Bonferroni correction for multiple comparisons. RESULTS: See Table. CONCLUSION: Pathways involved in protein degradation, and regulation of trophoblast invasion are important at all four gestational ages. However, the relative importance of different pathways diverges after that point among the four gestational ages. The possible clinical significance of the ubiquitin proteasome pathway may be underappreciated to date. Additional analyses with a larger sample size are required to understand how these pathways may play a role in predisposing to diseases of placental etiology, such as preeclampsia or intrauterine growth restriction. Pathway description, ( )over or ( )under represented vs human genome (reference) Poster Session IV Academic Issues, Antepartum Fetal, Clinical Ob, Fetus, Genetics, Hypertension, Med-Surg-Diseases, Operative Ob, U/S www.AJOG.org

Current applications and future needs for biomarkers in pediatric cardiomyopathy and heart failure: Summary from the Second International Conference on Pediatric Cardiomyopathy

Biomarkers have established an important role in the diagnosis and prognosis of heart failure in adults, with early indications being that their sensitivity and specificity will be similar in the pediatric population. Since early detection of remodeling is vital to preemptive management in cardiomyopathy and in heart disease arising from congenital lesions, biomarkers may offer a means of identifying high risk patients before they develop symptoms. Although in current use, natriuretic peptides high sensitivity troponins, and C-reactive protein need to have their applications more clearly defined in pediatrics, by evidence based guidelines. Exploratory work should meanwhile continue to define the risk of disease progression in patients with dilated cardiomyopathy, and of sudden death in hypertrophic cardiomyopathy based on biomarker profiles. Further research into the interaction of the genetic basis of disease and proteomic biomarkers will be a valuable means of assessing the importance of different pathways of disease related ventricular remodeling.

Acute Toxicity of Cadmium inDaphnia magnaunder Different Calcium and pH Conditions: Importance of Influx Rate

Water chemistry is generally thought to influence metal toxicity via affecting metal bioavailability and bioaccumulation, but its effects on tissue residue-based toxicity are poorly known. We conducted toxicity tests in parallel with uptake kinetics experiments of cadmium (Cd) in waters of different calcium (Ca) concentrations and pH levels using acclimated Daphnia magna as a model organism. Both the acute toxicity and uptake of Cd were reduced by higher Ca concentration and lower pH. Strikingly constant median effective influx rates (EJ(50), 1.3-1.6 μg g(-1) h(-1)) of Cd were observed when the concentration of Ca varied from 0.5 to 200 mg L(-1), indicating that acclimation to different Ca levels did not affect the tissue residue-based toxicity. The EJ(50) values increased consistently with decreasing pH level, showing that acclimation to acidic water decreased the tissue residue-based toxicity. With the use of calcium uptake inhibitors, we demonstrated that both Ca channel and Ca(2+)/Na(+) exchanger were involved in Cd uptake in daphnids, but there were also other possible pathways with higher affinity. The relative importance of different pathways was clearly dependent on the ambient Ca availability. Our findings are helpful for the development of a more accurate biotic ligand model in predicting the acute toxicity of Cd to daphnids.

Is the urothelium intelligent?

The urothelium separates the urinary tract lumen from underlying tissues of the tract wall. Previously considered as merely an effective barrier between these two compartments it is now recognized as a more active tissue that senses and transduces information about physical and chemical conditions within the urinary tract, such as luminal pressure, urine composition, etc. To understand this sensory function it is useful to consider the urothelium and suburothelium as a functional unit; containing uroepithelial cells, afferent and efferent nerve fibers and suburothelial interstitial cells. This structure responds to alterations in its external environment through the release of diffusible agents, such as ATP and acetylcholine, and eventually modulates the activity of afferent nerves and underlying smooth muscles. This review considers different stresses the urothelium/suburothelium responds to; the particular chemicals released; the cellular receptors that are consequently affected; and how nerve and muscle function is modulated. Brief consideration is also to regional differences in the urothelium/suburothelium along the urinary tract. The importance of different pathways in relaying sensory information in the normal urinary tract, or whether they are significant only in pathological conditions is also discussed. An operational definition of intelligence is used, whereby a system (urothelium/suburothelium) responds to external changes, to maximize the possibility of the urinary tract achieving its normal function. If so, the urothelium can be regarded as intelligent. The advantage of this approach is that input-output functions can be mathematically formulated, and the importance of different components contributing to abnormal urinary tract function can be calculated.

Structural and functional consequences of the Milano mutation (R173C) in human apolipoprotein A-I

Carriers of the apolipoprotein A-I(Milano) (apoA-I(M)) variant, R173C, have reduced levels of plasma HDL but no increase in cardiovascular disease. Despite intensive study, it is not clear whether the removal of the arginine or the introduction of the cysteine is responsible for this altered functionality. We investigated this question using two engineered variations of the apoA-I(M) mutation: R173S apoA-I, similar to apoA-I(M) but incapable of forming a disulfide bond, and R173K apoA-I, a conservative mutation. Characterization of the lipid-free proteins showed that the order of stability was wild type approximately R173K>R173S>R173C. Compared with wild-type apoA-I, apoA-I(M) had a lower affinity for lipids, while R173S apoA-I displayed intermediate affinity. The in vivo effects of the apoA-I variants were measured by injecting apoA-I-expressing adeno-associated virus into apoA-I-null mice. Mice that expressed the R173S variant again showed an intermediate phenotype. Thus, both the loss of the arginine and its replacement by a cysteine contribute to the altered properties of apoA-I(M). The arginine is potentially involved in an intrahelical salt bridge with E169 that is disrupted by the loss of the positively charged arginine and repelled by the cysteine, destabilizing the helix bundle domain in the apoA-I molecule and modifying its lipid binding characteristics.

Effects of sulfur on PCDD/F formation under stable and transient combustion conditions during MSW incineration

SO 2 levels in the flue gas from a laboratory-scale fluidized bed reactor combusting artificial municipal solid waste (MSW) were varied (resulting in four different SO 2:HCl ratios 0, 0.2, 0.7 and 2.7 (by mass)) to study the effects of sulfur on the formation of polychlorinated dibenzo- p-dioxins (PCDDs), polychlorinated dibenzofurans (PCDFs) and polychlorinated dibenzothiophenes (PCDTs). Sampling was performed simultaneously at three fixed points in the post-combustion zone with temperatures of 400, 300 and 200 °C, under normal combustion conditions and both during and after transient combustion conditions. The findings indicate that sulfur has a greater inhibitory effect on PCDF formation than on PCDD formation and that the PCDD/PCDF ratio in the flue gas depends on both the SO 2:HCl ratio in the flue gas and memory effects arising from transient combustion conditions. The results also indicate that the relative importance of different pathways shifts in the post-combustion zone; condensation products increasing with reductions in temperature and increases in residence time. However, these changes appear to depend on the SO 2:HCl ratio in the flue gas and combustion conditions. Sulfur seems to inhibit the chlorination of PCDFs. A tendency for increased SO 2 levels in the flue gas to increase levels of PCDTs was also detected, but the increases were much less significant than the reductions in PCDF levels.

Effects of acceptor composition and mechanism of ABCG1-mediated cellular free cholesterol efflux

Among the known mechanisms of reverse cholesterol transport (RCT), ATP binding cassette transporter G1 (ABCG1)-mediated free cholesterol (FC) transport is the most recent and least studied. Here, we have characterized the efficiencies of different acceptors using baby hamster kidney (BHK) cells transfected with human ABCG1 cDNA, which is inducible upon treatment with mifepristone. When normalized on particle number and particle surface area, the acceptor efficiency for FC efflux was as follows: small unilamellar vesicles (SUV)>LDL>reconstituted HDL>HDL2 = HDL3. Based on phospholipid content, the order was reversed. ABCG1 also mediated phospholipid efflux to human serum and HDL3. ABCG1-mediated FC efflux correlated significantly with a number of HDL subfractions and components in serum collected from 25 normolipidemic individuals: apolipoprotein A-II (apoA-II) (r2 = 0.7), apolipoprotein A-I (apoA-I) (r2 = 0.5), HDL-C (r2 = 0.4), HDL-PL (r2 = 0.4), α-2 HDL (r2 = 0.4), and preβ HDL (r2 = 0.2). ABCG1 did not enhance influx of FC or cholesteryl oleyl ether (COE) when cells were incubated with radiolabeled HDL3. ABCG1 expression did not increase the association of HDL3 with cells. Compared with control cells, ABCG1 expression significantly increased the FC pool available for efflux and the rate constant for efflux. In conclusion, composition and particle size determine the acceptor efficiency for ABCG1-mediated efflux. ABCG1 increases cell membrane FC pools and changes its rate of desorption into the aqueous phase without enhancing the association with the acceptor.