Seasonal and Spatial Variation of the Bacterial Mutagenicity of Fine Organic Aerosol in Southern California

The bacterial mutagenicity of a set of 1993 urban particulate air pollution samples is examined using the Salmonella typhimurium TM677 forward mutation assay. Ambient fine particulate samples were collected for 24 hr every sixth day throughout 1993 at four urban sites, including Long Beach, central Los Angeles, Azusa, and Rubidoux, California, and at an upwind background site on San Nicolas Island. Long Beach and central Los Angeles are congested urban areas where air quality is dominated by fresh emissions from air pollution sources; Azusa and Rubidoux are located farther downwind and receive transported air pollutants plus increased quantities of the products of atmospheric chemical reactions. Fine aerosol samples from Long Beach and Los Angeles show a pronounced seasonal variation in bacterial mutagenicity per cubic meter of ambient air, with maximum in the winter and a minimum in the summer. The downwind smog receptor site at Rubidoux shows peak mutagenicity (with postmitochondrial supernatant but no peak without postmitochondrial supernatant) during the September-October periods when direct transport from upwind sources can be expected. At most sites the mutagenicity per microgram of organic carbon from the aerosol is not obviously higher during the summer photochemical smog period than during the colder months. Significant spatial variation in bacterial mutagenicity is observed: mutagenicity per cubic meter of ambient air, on average, is more than an order of magnitude lower at San Nicolas Island than within the urban area. The highest mutagenicity values per microgram of organics supplied to the assay are found at the most congested urban sites at central Los Angeles and Long Beach. The highest annual average values of mutagenicity per cubic meter of air sampled occur at central Los Angeles. These findings stress the importance of proximity to sources of direct emissions of bacterial mutagens and imply that if important mutagen-forming atmospheric reactions occur, they likely occur in the winter and spring seasons as well as the photochemically more active summer and early fall periods

Considerations for design of source apportionment studies

This report recommends procedures for source and ambient sampling and analysis in source apportionment studies. The recommendations are based on the results of receptor model studies of atmospheric particles in urban areas, especially a recent study of Houston, TX, undertaken as part of the Mathematical and Empirical Receptor Models Workshop (Quail Roost II). The recommendations are presented at three levels of increasing cost and detail of information obtained. Existing mass emissions inventories combined with chemically resolved test data from similar sources (not necessarily in the same locale) can be used to initially estimate the sources of elements present on ambient particles. To aid local users in construction of chemically resolved emission estimates, the U.S. Environmental Protection Agency (EPA) is compiling a library of compositions and size distributions of particulate emissions from major source types. More reliable source characterization can be achieved if the actual sources are tested directly. EPA should develop and publish detailed procedures for source sampling that would be more appropriate for receptor model use than are existing standard methods. Source and ambient sampling should be conducted by similar methods. If possible, particles from sources should be collected in a way that simulates changes that would normally occur before they reach distant receptors (e.g. by diluting and cooling the particles from hot sources). It is recommended that particulate samples be routinely collected in two size fractions by use of virtual impactors and that all samples be subjected, at a minimum, to mass and X-ray fluorescence analyses. Additional measurements are suggested for obtaining more detailed information: neutron activation analysis; X-ray diffraction; automated particle classification by electron microscopy; analyses for classes of organic species, ^(14)C and thermally released carbonaceous species; and real-time observation of several gases during sample collection. Methods for collecting meteorological data in parallel with ambient samples are described, as are methods for incorporating such data into the source identification process

A case study of the culture of a high achieving suburban midwestern junior high school

The major purpose of this study was to examine the culture, i.e., the values, beliefs, and norms, in a high achieving junior high school. The study was designed to paint a portrait of the school\u27s culture;The study took place from September 1985 through June 1986. It included 16 days on-site distributed one to three days a month over the ten-month period. An ethnographic case study approach using observation, interviews, and artifact analysis was utilized;The school chosen for the study was Indian Hills Junior High School in West Des Moines, Iowa. The school is located in a middle to upper middle class community and has a consistent history of high academic achievement. To confirm the school\u27s positive climate a survey was given to the staff. Once the positive climate was confirmed observations, intensive interviews, and analysis of artifacts uncovered six dominant themes which permeated the school\u27s culture;As a result of the study the researcher formulated six assumptions about strong positive school cultures which are based upon those dominant themes: (1) The major force shaping the culture is the leadership provided by the principal, (2) A widely-shared value that people are important has a powerful effect upon the culture, (3) A positive learning climate is important in the culture, (4) A sense of pride is extremely important to staff and students in developing the culture, (5) Staff autonomy and intrapreneurship seem to have an uplifting effect on the culture, (6) The culture is a mixture of loosely coupled and tightly coupled systems;The results of the study are presented in three journal articles which richly describe the values, beliefs, and norms of the staff and students at Indian Hills. The articles provide insight as to how the school\u27s strong positive culture was developed

Enantiomeric Mixtures in Natural Product Chemistry: Separation and Absolute Configuration Assignment

Chiral natural product molecules are generally assumed to be biosynthesized in an enantiomerically pure or enriched fashion. Nevertheless, a significant amount of racemates or enantiomerically enriched mixtures has been reported from natural sources. This number is estimated to be even larger since the enantiomeric purity of secondary metabolites is rarely checked in the natural product isolation pipeline. This latter fact may have drastic effects on the evaluation of the biological activity of chiral natural products. A second bottleneck is the determination of their absolute configurations. Despite the widespread use of optical rotation and electronic circular dichroism, most of the stereochemical assignments are based on empirical correlations with similar compounds reported in the literature. As an alternative, the combination of vibrational circular dichroism and quantum chemical calculations has emerged as a powerful and reliable tool for both conformational and configurational analysis of natural products, even for those lacking UV-Vis chromophores. In this review, we aim to provide the reader with a critical overview of the occurrence of enantiomeric mixtures of secondary metabolites in nature as well the best practices for their detection, enantioselective separation using liquid chromatography, and determination of absolute configuration by means of vibrational circular dichroism and density functional theory calculations.Fed Univ Sao Carlos UFSCar, Dept Chem, Rod Washington Luis S-N,Km 235, BR-13565905 Sao Carlos, SP, BrazilFed Univ Sao Paulo UNIFESP, Inst Sci & Technol, R Talim 330, BR-12231280 Sao Jose Dos Campos, SP, BrazilFed Univ Sao Paulo UNIFESP, Inst Sci & Technol, R Talim 330, BR-12231280 Sao Jose Dos Campos, SP, BrazilWeb of ScienceSao Paulo Research Foundation (FAPESP)National Council for Scientific and Technological Development (CNPq-Brazil)CNPqFAPESP: 2013/01710-1, 2014/25222-9, 2015/07089-2, 2016/23794-0]|CNPq: 108265/2017-

The secreted triose phosphate isomerase of Brugia malayi is required to sustain microfilaria production in vivo

Human lymphatic filariasis is a major tropical disease transmitted through mosquito vectors which take up microfilarial larvae from the blood of infected subjects. Microfilariae are produced by long-lived adult parasites, which also release a suite of excretory-secretory products that have recently been subject to in-depth proteomic analysis. Surprisingly, the most abundant secreted protein of adult Brugia malayi is triose phosphate isomerase (TPI), a glycolytic enzyme usually associated with the cytosol. We now show that while TPI is a prominent target of the antibody response to infection, there is little antibody-mediated inhibition of catalytic activity by polyclonal sera. We generated a panel of twenty-three anti-TPI monoclonal antibodies and found only two were able to block TPI enzymatic activity. Immunisation of jirds with B. malayi TPI, or mice with the homologous protein from the rodent filaria Litomosoides sigmodontis, failed to induce neutralising antibodies or protective immunity. In contrast, passive transfer of neutralising monoclonal antibody to mice prior to implantation with adult B. malayi resulted in 60–70% reductions in microfilarial levels in vivo and both oocyte and microfilarial production by individual adult females. The loss of fecundity was accompanied by reduced IFNγ expression by CD4+ T cells and a higher proportion of macrophages at the site of infection. Thus, enzymatically active TPI plays an important role in the transmission cycle of B. malayi filarial parasites and is identified as a potential target for immunological and pharmacological intervention against filarial infections

The spatial range of peripheral collinear facilitation

Contrast detection thresholds for a central Gabor patch (target) can be modulated by the presence of co-oriented and collinear high contrast Gabors flankers. In foveal vision collinear facilitation can be observed for target-to-flankers relative distances beyond two times the wavelength (λ) of the Gabor's carrier, while for shorter relative distances (<2λ) there is suppression. These modulatory influences seem to disappear after 12λ. In this study, we measured contrast detection thresholds for different spatial frequencies (1, 4 and 6 cpd) and target-to-flankers relative distances ranging from 6 to 16λ, but with collinear configurations presented in near periphery at 4° of eccentricity. Results showed that in near periphery collinear facilitation extends beyond 12λ for the higher spatial frequencies tested (4 and 6 cpd), while it decays already at 10λ for the lowest spatial frequency used (i.e., 1 cpd). In addition, we found that increasing the spatial frequency the peak of collinear facilitation shifts towards larger target-to-flankers relative distances (expressed as multiples of the stimulus wavelength), an effect never reported neither for near peripheral nor for central vision. The results suggest that the peak and the spatial extent of collinear facilitation in near periphery depend on the spatial frequency of the stimuli used

Sorption of hydrophobic organic pollutants in saturated soil systems

Sorption equilibria and rates were characterized for a matrix of four aquifer sands and two slightly to moderately hydrophobic organic solutes (nitrobenzene and lindane), and the effects of sorption on the behavior of these solutes in saturated systems of the soils were determined. Experimental data were used to test and evaluate a variety of mathematical models for predicting contaminant fate and transport in groundwater systems.Observed equilibrium relationships between soil and solution phase solute concentrations were found to be described best by the nonlinear Freundlich isotherm model. It was further determined that the sorption process in the systems tested is rate controlled, requiring several days to approach equilibrium in completely mixed batch reactors. Subsequent modeling of solute transport in continuous flow soil column reactors was found to be most successful when rate-controlled models were used, the best results were obtained with a dual-resistance model incorporating the coupled mass transport steps of boundary-layer and intraparticle diffusion.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/26279/1/0000364.pd

Modeling the sorption of hydrophobic contaminants by aquifer materials--II. Column reactor systems

This is the second of a two-part series describing laboratory investigations and mathematical modeling of the sorption of hydrophobic solutes by aquifer materials. An evaluation is made of several rate and equilibrium models for description of solute sorption as a rational basis for predicting sorption processes in groundwater systems. The first paper presents and compares sorption in completely mixed batch-reactor systems while this paper addresses column-reactor systems. The results show that accurate representation of the sorption process can be obtained with either a dual-resistance diffusion model or an equilibrium/first-order sorption rate model. Changes in velocity of the fluid phase affect the magnitude of fitted model parameters, but changes in concentration have negligible influence on these parameters.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/27365/1/0000390.pd

The correlates of urinary albumin to creatinine ratio (ACR) in a high risk Australian Aboriginal community

Background: Albuminuria marks renal disease and cardiovascular risk. It was estimated to contribute 75% of the risk of all-cause natural death in one Aboriginal group. The urine albumin/creatinine ratio (ACR) is commonly used as an index of albuminuria. This study aims to examine the associations between demographic factors, anthropometric index, blood pressure, lipid-protein measurements and other biomarkers and albuminuria in a cross-sectional study in a high-risk Australian Aboriginal population. The models will be evaluated for albuminuria at or above the microalbuminuria threshold, and at or above the "overt albuminuria" threshold with the potential to distinguish associations they have in common and those that differ

Modeling the sorption of hydrophobic contaminants by aquifer materials--I. Rates and equilibria

This is the first of a two-part series describing experimental studies and numerical modeling of the sorption of hydrophobic contaminants by aquifer materials. The work focuses on the evaluation of predictive modeling methods for simulating sorption processes in groundwater systems. Equilibrium behavior and rates of approach to equilibrium were investigated for two hydrophobic solutes and three aquifer materials utilizing different reactor configurations. This paper discusses investigations conducted in completely mixed batch reactors. These investigations illustrate that sorption equilibria are nonlinear for the systems studied and that sorption rates involve an initial rapid step followed by a slower continuing uptake that can persist for several days. Alternative models for description of these equilibria and rate conditions are presented and compared. The second paper evaluates the use of sorption model coefficients determined from batch-reactor systems to model column-reactor systems.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/27364/1/0000389.pd