Chemical composition of Acid fog

Fog water collected at three sites in Los Angeles and Bakersfield, California, was found to have higher acidity and higher concentrations of sulfate, nitrate, and ammonium than previously observed in atmospheric water droplets. The pH of the fog water was in the range of 2.2 to 4.0. The dominant processes controlling the fog water chemistry appear to be the condensation and evaporation of water vapor on preexisting aerosol and the scavenging of gas-phase nitric acid.     

Metabolism at several levels of organization in the fruit of the avocado,Persea americana,Mill.

Studies conducted over a number of years offer opportunities for comparisons of oxidative and phosphorylative activities in fruits at the cellular and subcellular levels.In tissue slices placed in moist air as well as in the intact fruit the respiratory rise takes place at the expense of endogenous substrates, while the pattern of respiration in mitochondrial systems is determined by the acid of the Krebs cycle supplied. The change in oxidation rates between the preclimacteric and the climacteric stage is slight in the case of succinate but more striking with malate and with the keto acids. Thiaminepyrophosphate (TPP) plays a key role in determining the rates of oxidation in particles from unripe fruit and in preventing state 3 and state 4 inhibitions in mitochondria from climacteric peak avocados. Oxalacetate was implicated as the inhibitor and the mechanism of the inhibition studied.Inhibitors were used to learn about the electron transport chain in the avocado. When amytal, cyanide, azide and DNP were applied to tissue slices a remarkable stimulation of oxygen uptake was noted, especially in the preclimacteric stage. A return to control rates was achieved by a combination of inhibitors. The response to single inhibitors was explained by mobilization of limiting cofactors to fewer active sites. Coexistence of phosphorylative and non-phosphorylative pathways was also implicated. The use of inhibitors on mitochondrial preparations presented a strikingly different picture by blocking the oxidase and the carriers. In order to resolve the contradiction more knowledge is needed about the relative contributions of the soluble and the particulate systems at the cellular level.The action of 2,4-dinitrophenol (DNP) served as a basis for theories of ripening. When phosphate metabolism was examined in tissue slices the effects of DNP on the incorporation of³²P into esters did not differ materially between the two stages. However the rate of esterification into all esters examined increased greatly with ripening. Similarly, the ADP/O ratios in mitochondrial system increased indicating improvement on phosphorylative activities as the climacteric progresses.The inescapable conclusion is that the machinery for energy generation is in full operation throughout the climacteric. The suggestion was made that for metabolic impairments leading to senescence the search should be directed to protein and nucleic acid metabolism.

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Zusammenfassung Studien über eine Reihe von Jahren geben Gelegenheit zu Vergleichen über die oxidativen und phosphorylativen Aktivitäten in Früchten auf zellularem und subzellularem Niveau.Sowohl in Gewebeschnitten — in feuchter Luft gehalten — als auch in der intakten Frucht wird der Anstieg der Atmung von einer Abgabe endogener Substanzen begleitet, während das Muster der Atmung in den mitochondrischen Systemen bestimmt wird durch die Säure, die vom Krebs-Zyklus zugeführt wird. Die Änderung in den Oxidationsraten während des Vor- und Nachreifestadiums ist gering im Falle von Succinat, aber auffallend grösser bei Malat und den Ketosäuren. Thiaminpyrophosphat (TPP) spielt eine Schlüsselrolle in der Bestimmung der Oxidationsrate in Teilchen unreifer Früchte und bei Verhinderung der Hemmung der Stufen 3 und 4 in Mitochondrien von Avocados, die auf dem Höhepunkt der Nachreife standen. Oxalacetat war als Inhibitor beteiligt und der Mechanismus der Hemmung wurde studiert.Inhibitoren dienten dazu, die Elektronen-Transportkette in der Avocado kennenzulernen. Wurden Amytal, Cyanid, Azid und DNP Gewebeschnitten appliziert, ergab sich eine bemerkenswerte Stimulation der Sauerstoff-Aufnahme insbesondere im Vorreife-Stadium. Ein Abfall auf Kontroll-Werte ergab sich durch eine Kombination von Inhibitoren. Das Ansprechen auf einzelne Inhibitoren wurde mit einer Mobilisierung limitierender Kofaktoren gegenüber weniger aktiven Stellen erklärt. Die Koexistenz phosphorylativer und nicht-phosphorylativer Wege wurde mithin gefolgert. Der Gebrauch von Inhibitoren auf mitochondrischen Präparaten gibt ein auffallend verschiedenes Bild durch Blockieren der Oxidase und des Trägers. Um den Widerspruch zu lösen, ist mehr Kenntnis über die relativen Beiträge des löslichen und der Teilchen-Systeme auf dem zellularen Niveau notwendig.Die Tätigkeit von 2,4-Dinitrophenol (DNP) diente als Basis für die Theorie der Reifung. Wurde der Phosphat-Metabolismus in Gewebeschnitten untersucht, unterschieden sich die Effekte der DNP auf den Einbau von³²P in Ester nicht wesentlich zwischen den beiden Stufen. Nichtsdestoweniger stieg die Veresterungs-Rate in allen geprüften Estern stark mit der Reifung an. Ähnlich nahmen auch die ADP/O-Verhältnisse im mitochondrischen System zu und gaben eine Verbesserung in den phosphorylativen Aktivitäten wie den Nachreife-Fortschritt an.Die unausweichliche Schlussfolgerung ist, dass die Maschinerie für die Energie-Erzeugung während der Nachreife in voller Tätigkeit ist. Die Vorstellung wurde entwickelt, dass für die Beeinträchtigung des Stoffwechsels, die zum Altern führt, die Suche in Richtung Protein- und Nucleinsäuren-Umwandlung gelenkt werden sollte.

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Resume Les travaux menés depuis un certain nombre d'années permettent de comparer les activités d'oxydation et de phosphorylation du fruit aux niveaux cellulaire et subcellulaire.Sur des tranches de tissus placées à l'air humide, aussi bien que dans le fruit intact, l'accroissement de l'activité respiratoire a lieu au détriment de substrats endogènes, tandis que, dans les mitochondries isolées, le type de respiration est déterminé par le type d'acide du cycle de Krebs fourni. La variation de l'intensité des oxydations, lorsque le fruit passe de l'étape préclimactérique à l'étape climactérique, est faible dans le cas où l'acide fourni est le succinate, mais plus forte dans le cas du malate et des cétoacides. La thiaminepyrophosphate (TPP) joue un rôle essentiel dans le déterminisme des vitesses d'oxydation par les particules préparées à partir de fruits non mûrs; elle empêche l'action d'un inhibiteur aux stades 3 et 4 dans le cas des mitochondries préparées à partir des fruits d'avocats se trouvant en pleine crise climactérique. L'oxaloacétate semble être cet inhibiteur; le mécanisme de l'inhibition est étudié.Des inhibiteurs ont été utilisés pour étudier la chaîne de transport d'électrons chez l'avocat. Lorsqu'on applique à des tranches de tissus de l'amytal, du cyanure, de l'azide ou du DNP, une stimulation importante de la consommation d'oxygène est observée surtout dans la période préclimactérique. Un retour aux vitesses témoins a été obtenu en utilisant une combinaison d'inhibiteurs. La réponse à un seul inhibiteur est expliquée par la mobilisation de cofacteurs limitants vers un nombre réduit de sites actifs. La coexistence de voies phosphorylantes et non-phosphorylantes est aussi impliquée. Lorsqu'on applique les inhibiteurs à des préparations de mitochondries, des résultats fort différents sont obtenus: dans ce cas, les inhibiteurs bloquent les oxydases et les transporteurs. Pour résoudre cette contradiction, des études complémentaires sont nécessaires sur les contributions relatives des systèmes solubles et particulaires au niveau cellulaire.L'action du 2,4-dinitrophenol (DNP) a servi de base pour des théories de la maturation. Lorsqu'on examine le métabolisme du phosphate dans les tranches de tissus, on observe que les effets du DNP sur l'incorporation du³²P dans les esters ne different pas entre les 2 étapes de la maturation. Cependant, la vitesse d'incorporation dans tous les esters examinés augmente fortement avec la maturation. De même, les rapports ADP/O dans le système mitochondrial augmente, montrant ainsi une augmentation des activités de phosphorylation au fur et à mesure que progresse le climactérique.La conclusion qu'on est obligé de tirer de ces faits, est que le système de production d'énergie fonctionne à plein rendement tout au long du climactérique. L'auteur suggère que la cause des déficiences métaboliques conduisant à la senescence doit être recherchée du côté du métabolisme des protéines et des acides nucléiques.

     

A molecular basis for MHC class II--associated autoimmunity

Class II major histocompatibility (MHC) molecules have an immunoregulatory role. These cell-surface glycoproteins present fragments of protein antigens (or peptides) to thymus-derived lymphocytes (T cells). Nucleotide sequence polymorphism in the genes that encode the class II MHC products determines the specificity of the immune response and is correlated with the development of autoimmune diseases. This study identifies certain class II polymorphic amino acid residues that are strongly associated with susceptibility to insulin-dependent diabetes mellitus, rheumatoid arthritis, and pemphigus vulgaris. These findings implicate particular class II MHC isotypes in susceptibility to each disease and suggest new prophylactic and therapeutic strategies.     

Pharmacokinetics,efficacy and convulsive dose of articaine hydrochloride in goat kids

ObjectiveTo investigate the pharmacokinetics, efficacy and convulsive dose of articaine hydrochloride in goat kids.Study designExperimental prospective study.AnimalsA total of 18 (n = 6 animals per experiment) male Saanen goat kids (2–4 weeks old).MethodsThe study consisted of three experiments. The first determined the pharmacokinetics of articaine following intravenous administration of articaine hydrochloride (8 mg kg^–1). The second experiment investigated the anaesthetic efficacy and pharmacokinetics following cornual nerve block using 1.5% articaine hydrochloride. Anaesthesia of horn buds was evaluated using the response to pinprick test. Non-compartmental analysis was used. The final experiment determined the convulsive dose of articaine and its corresponding plasma concentration following intravenous infusion of articaine hydrochloride (4 mg kg^–1 minute^–1). Data are shown as mean ± standard deviation.ResultsThe mean terminal half-life (t_1/2λz), mean volume of distribution at steady state (Vd_ss) and mean plasma clearance (CL) of articaine following intravenous administration were 0.66 hour, 3.81 L kg^–1 and 5.33 L hour^–1 kg^–1, respectively. After cornual nerve block, the mean maximum plasma concentration of articaine was 587 ng mL^–1 at 0.22 hour and its mean t_1/2λz was 1.26 hours. Anaesthesia of horn buds was observed within 4 minutes following cornual nerve block. The mean dose required to produce convulsions was 16.24 mg kg^–1 and mean convulsive plasma concentrations of articaine and articainic acid were 9905 and 1517 ng mL^–1, respectively.ConclusionsIntravenous administration of 8 mg kg^–1 of articaine hydrochloride did not cause any adverse effects. Pharmacokinetic data suggest that articaine was rapidly eliminated and cleared. Cornual nerve block using 1.5% articaine hydrochloride alleviated the response to the acute nociceptive stimulus during disbudding.Clinical relevanceArticaine hydrochloride appears to be a safe and effective local anaesthetic for disbudding in goat kids.     

Molecular pathogenesis of equine coital exanthema: temperature-sensitive function(s) in cells infected with equine herpesviruses

Preliminary experiments have revealed that several laboratory and wild-type strains of the equine herpesvirus (EHV) triad were temperature-sensitive for growth when assayed at 39 degrees C. The efficiencies of plating (EOP) observed were 10(-2) for both EHV 1 and 2, and 1 X 10(-6) for EHV 3. The EOPs were determined by plaque assays which compared titrations at 34 degrees C and 39 degrees C on equine fetal dermal fibroblast cells. Growth yield experiments, assayed at 34 degrees C, reflected those EOP's, but did not indicate any difference in yields when infected cultures were incubated at 34 degrees C and 37 degrees C. Temperature shift experiments with EHV 3-infected cultures revealed that a temperature-sensitive function(s) responsible for the reduction in titer appeared to be a late function(s). All strains examined appeared to incorporate H3-thymidine into viral-density DNA at the non-permissive temperature of 39 degrees C. Electron microscopy of EHV 3-infected cell cultures, incubated continuously at the non-permissive temperature and examined at 18 h after infection, revealed structures consistent with the accumulation of nucleocapsids within the nucleus. The evidence presented is consistent with the hypothesis that in equine dermal cells infected with a plaque-purified wild-type strain of EHV 3 (1118LP), a function needed for the egress of nucleocapsids from the nucleus is absent at 39 degrees C. The significance of these findings relative to the pathogenicity of the disease (equine coital exanthema) caused by this virus is discussed.     

Revision and application of the LINKAGES model to simulate forest growth in central hardwood landscapes in response to climate change

Context

Global climate change impacts forest growth and methods of modeling those impacts at the landscape scale are needed to forecast future forest species composition change and abundance. Changes in forest landscapes will affect ecosystem processes and services such as succession and disturbance, wildlife habitat, and production of forest products at regional, landscape and global scales.

Objectives

LINKAGES 2.2 was revised to create LINKAGES 3.0 and used it to evaluate tree species growth potential and total biomass production under alternative climate scenarios. This information is needed to understand species potential under future climate and to parameterize forest landscape models (FLMs) used to evaluate forest succession under climate change.

Methods

We simulated total tree biomass and responses of individual tree species in each of the 74 ecological subsections across the central hardwood region of the United States under current climate and projected climate at the end of the century from two general circulation models and two representative greenhouse gas concentration pathways.

Results

Forest composition and abundance varied by ecological subsection with more dramatic changes occurring with greater changes in temperature and precipitation and on soils with lower water holding capacity. Biomass production across the region followed patterns of soil quality.

Conclusions

Linkages 3.0 predicted realistic responses to soil and climate gradients and its application was a useful approach for considering growth potential and maximum growing space under future climates. We suggest Linkages 3.0 can also can used to inform parameter estimates in FLMs such as species establishment and maximum growing space.