The Southeastern Aerosol Research and Characterization (SEARCH) study: temporal trends in gas and PM concentrations and composition, 1999-2010.

UNLABELLED: The SEARCH study began in mid 1998 with a focus on particulate matter and gases in the southeastern United States. Eight monitoring sites, comprising four urban/nonurban pairs, are located inland and along the coast of the Gulf of Mexico. Downward trends in ambient carbon monoxide (CO), sulfur dioxide (SO2), and oxidized nitrogen species (NOy) concentrations averaged 1.2 +/- 0.4 to 9.7 +/- 1.8% per year from 1999 to 2010, qualitatively proportional to decreases of 4.7 to 7.9% per year in anthropogenic emissions of CO, SO2, and oxides of nitrogen (NOx) in the SEARCH region. Downward trends in mean annual sulfate (SO4) concentrations ranged from 3.7 +/- 1.1 to 6.2 +/- 1.1% per year approximately linear with, but not 1:1 proportional to, the 7.9 +/- 1.1% per year reduction in SO2 emissions from 1999 to 2010. The 95th percentile of the March-October peak daily 8-hr ozone (O3 concentrations decreased by 1.1 +/- 0.4 to 2.4 +/- 0.6 ppbv per year (1.5 +/- 0.6 to 3.1 +/- 0.8% per year); O3 precursor emissions of NOx and volatile organic compounds (VOC) decreased at rates of 4.7 and 3.3% per year, respectively. Ambient particulate nitrate (NO3) concentrations decreased by 0.6 +/- 1.2 to 5.8 +/- 0.9% per year modulated in comparison with mean annual ambient NOy concentration decreases ranging from 6.0 +/- 0.9 to 9.0 +/- 1.3% per year. Mean annual organic matter (OM) and elemental carbon (EC) concentrations declined by 3.3 +/- 0.8 to 6.5 +/- 0.3 and 3.2 +/- 1.4 to 7.8 +/- 0.7% per year. The analysis demonstrates major improvements in air quality in the Southeast from 1999 to 2010. Meteorological variations and incompletely quantified uncertainties for emission changes create difficulty in establishing unambiguous quantitative relationships between emission reductions and ambient air quality. IMPLICATIONS: Emissions and secondary pollutants show complex relationships that depend on year-to-year variations in dispersion and atmospheric chemistry. The observed response of 03 to NOx and VOC emissions in the Southeast implies that continuing reductions of precursor emissions, probably achieved through vehicle fleet turnover and emission control measures, will be needed to attain the National Ambient Air Quality Standard for O3. Reductions in fine particle concentrations have resulted from reductions of primary PM, especially EC and a portion of OM, and from reduction of gas precursors known to form particles, especially SO4 from SO2. Continued reduction of PM2.5 mass concentrations will require attention to organic constituents, which may be complicated by potentially unmanageable biogenic species present in the Southeast.

The Southeastern Aerosol Research and Characterization (SEARCH) study: spatial variations and chemical climatology, 1999-2010.

UNLABELLED: The Southeastern Aerosol Research and Characterization (SEARCH) study, which has been in continuous operation from 1999 to 2012, was implemented to investigate regional and urban air pollution in the southeastern United States. With complementary data from other networks, the SEARCH measurements provide key knowledge about long-term urban/nonurban pollution contrasts and regional climatology affecting inland locations and sites along the Gulf of Mexico coastline. Analytical approaches ranging from comparisons of mean concentrations to the application of air mass trajectories and principal component analysis provide insight into local and area-wide pollution. Gases (carbon monoxide, sulfur dioxide, nitrogen oxides, ozone, and ammonia), fine particle mass concentration, and fine particle species concentrations (including sulfate, elementary carbon, and organic carbon) are affected by a combination of regional conditions and local emission sources. Urban concentrations in excess of regional baselines and intraurban variations of concentrations depend on source proximity, topography, and local meteorological processes. Regional-scale pollution events (95th percentile concentrations) involving more than 6 of the 8 SEARCH sites are rare (< 2% of days), while subregional events affecting 4-6 sites occur on approximately 10% of days. Regional and subregional events are characterized by widely coincident elevated concentrations of ozone, sulfate, and particulate organic carbon, driven by persistent synoptic-scale air mass stagnation and higher temperatures that favor formation of secondary species, mainly in the summer months. The meteorological conditions associated with regional stagnation do not favor long-range transport of polluted air masses during episodes. Regional and subregional pollution events frequently terminate with southward and eastward penetration of frontal systems, which may initially reduce air pollutant concentrations more inland than along the Gulf Coast. IMPLICATIONS: Regional distribution of emission sources and synoptic-scale meteorological influences favoring stagnation lead to high regionwide pollution levels. The regional influence is greatest with secondary species, including ozone (03) particulate sulfate (SO4), and particulate organic matter, some of which is produced by atmospheric oxidation of volatile organic compounds (VOCs) from vegetation and anthropogenic sources. Other species, many of which are from primary emissions, are more influenced by local sources, especially within the Atlanta, GA, and Birmingham, AL, metropolitan areas. Limited measurements of modern and fossil total carbon point to the importance of biological and biogenic emissions in the Southeast.

Studies on human antibodies. V. Amino acid composition of antidextrans of the same and of differing specificities from several individuals.

Human dextran-antidextran-specific precipitates from individuals immunized with dextrans containing either one or two antigenic determinants, were analyzed for their content of various amino acids. Large differences in certain amino acids were found among alpha-(1 --> 6)-specific antidextrans. Wide variations were also observed in antidextran fractions from a given individual specific for alpha-(1 --> 6)- and alpha-(1 --> 2)-linked glucose residues.

Action of cytochalasin D on cells of established lines. II. Cortex and microfilaments.

Cells in culture exposed to cytochalasin D (CD) rapidly undergo a long-sustained tonic contraction. Coincident with this contracture the thin microfilaments of the cortex become compacted into feltlike masses. The ravelled filaments of these masses remain actinlike and bind heavy meromyosin; they are not disrupted or disaggregated, but rather, appear to represent a contracted state of the microfilament apparatus of the cell cortex. On continued exposure to CD, 'myoid' bundles, containing thick, dense filaments, and larger fusiform or ribbonlike, putatively myosinoid, aggregates may appear. These appearances are interpreted as consequences of a state of hypercontraction without relaxation induced by CD. They do not occur in CD-treated cells prevented from contracting by inhibitors of energy metabolism, and are readily reversible on withdrawal of CD. Extensive ordered arrays of thin microfilaments develop in cells which are reextending during early recovery.

Action of cytochalasin D on cells of established lines. III. Zeiosis and movements at the cell surface.

The projection of knobby protuberances at the cell surface (zeiosis) is a general cellular response to cytochalasin D (CD), resulting from herniation of endoplasm through undefended places of the cortex during cell contractions and displacement of microfilaments induced by CD. Zeiosis is prevented by agents that interfere with the contractile response to CD, such as inhibitors of energy metabolism or cyclic AMP. The developed protrusions, which remain relatively stable in the presence of CD, contain chiefly mono- or subribosomes, and occasionally other organelles normally resident in endoplasm; compact microfilament felt occupies their bases and extends into their proximal stalks. Protein synthesis in the knobs is less than half of that in the polyribosome-containing endoplasm residual in the main body of the cell. Knobs first protrude singly near the margin of the contracting cells and rapidly cluster into small groups in the periphery even at lower temperature. The clusters then migrate centripetally and coalesce into a large aggregate near the apex of the immobilized and retracted cell: this movement is energy- and temperature-dependent. Aggregation is more prominent and stable in cell lines of epithelial derivation than in fibroblastic or other lines in which nuclear extrusion occurs more readily. The latter is regarded as a special manifestation of zeiosis. Macromarkers, such as latex spherules, migrate like the zeiotic knobs on the cell surfaces in the presence of CD. The aggregated knobs, although persistent for days in the presence of CD, are rapidly recessed after withdrawal of the agent as ruffling is resumed and the cells spread. These movements are discussed in terms of current concepts of mobility of the cell membrane.

Action of cytochalasin D on cells of established lines. I. Early events.

HeLa, Vero, L, HEp2, and MDBK cells respond immediately to 0.2-0.5 microg/ml cytochalasin D (CD) with sustained contraction (contracture), loss of microvilli, expression of endoplasmic contents (zeiosis), nuclear protrusion, and extension of cytoplasmic processes. The development of these changes is depicted, and the dose-response patterns in these cell lines are described. MDBK is generally most resistant and HeLa most sensitive to these effects of CD. Cells in G(1) are most sensitive to CD; responsiveness decreases progressively during early S and is least in mid S through G(2). CD inhibits transport of [(14)C]deoxyglucose in HeLa by about 45% but has no significant effect on hexose uptake in Vero and MDBK; sugar transport is thus apparently unrelated to any morphologic effect of CD. Although spreading and attachment are impeded, CD does not decrease and may even enhance the adhesiveness of established monolayers. Contraction appears to be a primary early effect of CD, upon which other visible changes follow. It is prevented by some inhibitors of energy metabolism (deoxyglucose and dinitrophenol) and does not occur in glycerinated models without ATP. The possible bases of the contractile response to CD are discussed. Although direct or indirect action of CD on some microfilaments may occur, a generalized structural disruption of contractile filaments by CD is considered unlikely.

Subcellular localization of binding sites for cytochalasin D: evidence from activation energies.

The activation energies for binding of tritiated cytochalasin D to HEp-2 cells and isolated plasma membrane were determined by Arrhenius plots. The higher value for intact cells (24 kcal/mol) compared to the plasma membrane fraction (4 kcal/mol at greater than 11.5 degrees C, 18 kcal/mol at less than 11.5 degrees C) was taken as evidence that [3H]cytochalasin D must penetrate the plasma membrane in order to reach its binding sites. The data support the conclusion that binding sites for [3H]cytochalasin D are intracellular, on the cytoplasmic face of the plasma membrane (rather than within the lipid bilayer), and on microsomes (endomembranes).

Purification and properties of Arthrobacter neuraminidase.

Neuraminidase (EC 3.2.1.18) from an Arthrobacter species was purified homogeneity by conventional procedures (yield approx. 1 mg/1) and was judged to be homogeneous by sodium dodecyl sulfate gel electrophoresis. Gel electrofocusing of neuraminidase revealed 1 major band (85-90%), pI 5.35 +/- 0.05, and 6 minor bands, whose pI ranged from 5.25 to 5.70, and each of which had catalytic activity. Arthrobacter neuraminidase is a monomeric glycoprotein of molecular weight 88 000, has an apparent Km of 7.8-10(-4) M for N-acetylneuraminlactose, is insensitive to inhibition by N-acetylneuraminic acid, and is about 2% carbohydrate by weight. The amino acid composition as well as the galactosamine and glucosamine content was determined. The enzyme can hydrolyze (alpha, 2-3), (alpha, 2-6), (alpha, 2-8) linkages. The active size of the enzyme appears to be inaccessible since no inhibition was observed by reagents known to modify sulfhydryl, lysyl, carboxyl, histidinyl, and argininyl residues. In contrast, N-bromosuccinimide at a 60-fold molar ratio to enzyme, gave complete inhibition. These results suggest that a tryptophan residue is essential for catalysis.

A screen for dominant modifiers of the irreC-rst cell death phenotype in the developing Drosophila retina.

Programmed cell death (PCD) in the Drosophila retina requires activity of the irregular chiasmC-roughest (irreC-rst) gene. Loss-of-function mutations in irreC-rst block PCD during retinal development and lead to a rough eye phenotype in the adult. To identify genes that interact with irreC-rst and may be involved in PCD, we conducted a genetic screen for dominant enhancers and suppressors of the adult rough eye phenotype. We screened 150,000 mutagenized flies and recovered 170 dominant modifiers that localized primarily to the second and third chromosomes. At least two allelic groups correspond to previously identified death regulators, Delta and dRas1. Examination of retinae from homozygous viable mutants indicated two major phenotypic classes. One class exhibited pleiotropic defects while the other class exhibited defects specific to the cell population that normally undergoes PCD.

Photoaffinity labeling of plasma membrane receptors for cytochalasins in Ehrlich tumor cells.

Treatment of purified Ehrlich ascites cell plasma membranes either with [3H]cytochalasin B or [3H]19-O-acetylchaetoglobosin A under photolytic conditions produced several radioactive polypeptides which were characterized by SDS-PAGE analyses. The major proteins so photolabeled were in the 60,000-80,000 Da range, with less labeling found in polypeptides smaller than 43,000 and greater than 90,000 Da. Immunofluorescent staining failed to identify the major photolabeled component as actin. It is concluded, in keeping with prior investigations using other cell types, that the predominant proteins photolabeled by cytochalasins are affiliated with the glucose-transport system.

Structure-activity correlations of cytochalasins. Novel halogenated and related cytochalasin C and D derivatives.

A series of halogenated and related analogues of cytochalasin C (CC) and D (CD) has been synthesized, and the biological activities of the analogues as inhibitors in a cell-free contractility model system obtained from Ehrlich ascites tumor cells were evaluated. The reaction sequence involved treatment of CD with phenyltrimethylammonium perbromide to give 6,12-dibromo-CD (2), dehydrohalogenation of 2 to 12-bromo-CC (3), and the subsequent conversions of 3 to 12-azido- (4), 12-iodo- (5), and 12-cyano-CC (6). The ID50 values for 5, 3, 4, 2, and 6 are 6.0, 7.4, 8.8, 45, and 77 X 10(-7) M, respectively, in comparison to ca. 2.8 X 10(-7) M for the parental compounds. The potential cell and molecular biological applications of these compounds are delineated.

Flecainide-induced sustained ventricular tachycardia successfully treated with lidocaine.

A 69-year-old man had new sustained ventricular tachycardia caused by flecainide which promptly responded to intravenous lidocaine therapy. Discontinuation of the lidocaine infusion resulted in the reappearance of ventricular tachycardia which again immediately terminated after lidocaine was given. In this case, lidocaine effectively reversed the proarrhythmic effects of flecainide.

Think before you prep: defining the terms of change in American healthcare.

United States physicians are grappling with a fundamental reorganization of the healthcare system. Although many remain skeptical of governmental efforts at reform, they seem to take as given an industrial efficiency model of change, including large and integrated managed care arrangements and performance measurement based on outcomes such as quality. This uncharacteristic acquiescence seems to derive in part from a confounding of concepts. This article makes three distinctions: among knowledge about practice, knowledge about quality, and outcomes research; between outcomes research and the outcomes movement; and between the outcomes movement and other options for healthcare reform. The suggestion that statistical measurement of specific variables ought not to have a priori precedence over other ways of thinking--and doing something--about healthcare is made.

"Medical effectiveness" in Canadian and U.S. health policy: the comparative politics of inferential ambiguity.

OBJECTIVE: To compare Canadian and U.S. policymaking to determine how different health care systems may use health services research differently in responding to the common problem of ineffective medical care. DATA SOURCES/STUDY DESIGN/DATA COLLECTION: Not applicable. PRINCIPAL FINDINGS: The United States and Canada are making surprisingly divergent responses to the problem of medical ineffectiveness: reinforcement of the solidarity principle and deprivatization in Canada, and reinforcement of market competition and privatization in the United States. In doing so, Canadian policymakers overstate the societal applicability and U.S. policymakers the individual applicability of outcomes research findings. CONCLUSIONS: Probabilistic findings of medical effectiveness are fundamentally ambiguous as they relate to action. They therefore invite divergent policy responses from different policy regimes. Health services researchers must not imagine that research findings are sufficient to determine the course of health policy.

Evidence and expertise: the challenge of the outcomes movement to medical professionalism.

The outcomes movement--including evidence-based medicine--challenges medicine as a profession by disputing what and how physicians know. First, the movement considers probabilistic research to be virtually the only way to arrive at knowledge in medicine. Second, it insists on objective or impersonal knowledge (statistically manipulated, hard, aggregate data). Such knowledge does not come from within the professional relationship; rather it is gathered across relationships and is offered to the practitioner from the outside. Third, the outcomes movement is motivated by a desire for certainty, promising definitive solutions that will reduce variation and waste. What professionals know, in contrast, is inherently and irreparably uncertain. Fourth, the movement expects physicians to implement the findings from probabilistic research through application. The inferential leap necessary for treating an individual based on aggregate findings is mostly assumed away. Finally, the outcomes movement promotes rule-based behavior on the part of physicians in an effort, among other things, to eliminate variation in medical practice. But professionals do not follow rules per se--they intuit what is right in a situation, including, sometimes, that it is right to defer to a rule. Professional knowledge in medicine is both larger and smaller than the knowledge conceived of by the outcomes movement. The latter is built of probabilistic research and translated into physician directives. Professional knowledge, in contrast, partakes of statistical knowledge and bench science, as well as various forms of personal knowledge, including the experiential. Physicians will continue to need professional knowledge, which allows for the complexity of physician experience and for the immediacy and individuality of patients.

The role of the conjugated carbonyl of cytochalasin A in contractility inhibitions.

A study of the mechanism of action of cytochalasin A (CA) in relation to its structural features and to its selective inhibition of certain contractile processes has been initiated. Quantitative structure-function analyses with several CA-related cytochalasins - including synthetic 21,22-dihydro-CA (DHCA), the 22-beta mercaptoethanol CA-adduct, (CA-2ME), and the 22-dithiothreitol CA-adduct (CA-DTT) - have been carried out in a temperature sensitive gel-sol extract from Ehrlich ascites tumor cells. Each drug congener was purified to homogeneity by HPLC prior to biological testing. The undiminished inhibitory indices of DHCA and CA-2ME (ID50 congruent to 3.7 x 10(-7) M) overrules the prior circumstantial evidence accumulated for the obligatory electrophilic interaction of this drug, at its alpha-beta-unsaturated ketone region, with presumptive receptor nucleophiles.

2,3-Dehydro-4-epi-N-acetylneuraminic acid; a neuraminidase inhibitor.

Treatment of N-acetylneuraminic acid methyl ester with sulfuric acid and acetic anhydride at 50 degrees followed by deacetylation gave 2,3-dehydro-2-deoxy-N-acetylneuraminic acid methyl ester and methyl 5-acetamido-2,6-anhydro-2,3,5-trideoxy-D-glycero-D-talo-non-2-enonate (2,3-dehydro-4-epi-NeuAc methyl ester) in equal yields (approximately 40% each). The structure of the latter was ascertained primarily from analysis of its mass spectrum and 1H- and 13C-nuclear magnetic resonance spectra. The relative proportions of these two glycals in the foregoing reaction was dependent on temperature, as at 0 degrees, the yield of 2,3-dehydro-4-epi-NeuAc was markedly diminished. A minor by-product of this acetylation reaction was 2-methyl-(methyl 7,8,9-tri-O-acetyl-2,6-anhydro-2,3,5-trideoxy-D-glycero-D-talo-non-2-enonate)-[ 4,5-d]-2-oxazoline. Based upon this finding and additional interconversion experiments, a mechanism involving the intermediacy of the latter oxazoline to account for the epimerization is proposed. These glycals and their methyl esters are competitive inhibitors of Arthrobacter sialophilus, neuraminidase, suggesting that the 4-hydroxyl group must be equatorially oriented for maximal enzyme inhibition.

Structural features of cytochalasins responsible for gram-positive bacterial inhibitions.

A study of the relative effectiveness of some eighteen natural and synthetically modified cytochalasins on the uptake of glucose by the Gram-positive bacterium Arthrobacter sialophilus showed that cytochalasins B, C or D and aspochalasins A, C or D were inactive natural congeners. The presence of an alpha,beta-unsaturated carbonyl group in the macrolide moiety of these compounds with appropriate bioisosteric placement, as exemplified by cytochalasin A and aspochalasin B, are requisite molecular features. The transmembrane inhibitory index of active compounds was enhanced by increasing their lipophilicity. Thiol adducts of CA were around 20% as active in solute uptake inhibition as was the free drug. Radioactive 7-O-acetyl CA and its thiol adduct were each rapidly taken up by A. sialophilus and remained firmly bound to cellular components even after denaturant manipulations. These findings provide strong evidence for a stable association between CA and presumptive macromolecular receptors in transport and related processes.

Getting there from here: evidentiary quandaries of the US outcomes movement.

The US outcomes movement assumes, and sometimes argues, the primacy for medical practice of probabilistic knowledge derived from methodologically rigorous statistical studies. 'Evidence-based medicine,' then, is considered a course of clinical medicine prescribed by such research. Implementation of evidence-based medicine as recently been uneven in the US, manifesting not only the expected 'obstacles to implementation' but several theoretical weakness of the applied science model of medical care. Outcomes researchers claim to provide certainty - certainty of what is probable, as it turns out - in a world of clinical uncertainty. This paper argues that outcomes research actually exacerbates the inferential uncertainty of practising physicians who would use knowledge for practice. Two quandaries are discussed: whether to privilege rigorous or relevant research, and whether to privilege universal or local knowledge. In each case, the logic of 'evidence-based medicine' is insufficient to resolve the quandary and would seem to support conflicting resolutions. Recent developments in US health policy are cited as manifestations of these quandaries. Finally, the reader is asked not to disregard the political implications of the outcomes movement.