Search

To survey landscape-scale fluxes of biogenic gases, a 100 m Teflon tube was attached to a tethered balloon as a sampling inlet for a fast response Proton Transfer Reaction Mass Spectrometer (PTRMS). Along with meteorological instruments deployed on the tethered balloon and at 3 m and outputs from a regional weather model, these observations were used to estimate landscape scale biogenic volatile organic compound fluxes with two micrometeorological techniques: mixed layer variance and surface layer gradients. This highly mobile sampling system was deployed at four field sites near Barcelona to estimate landscape-scale BVOC emission factors in a relatively short period (3 weeks). The two micrometeorological techniques agreed within the uncertainty of the flux measurements at all four sites even though the locations had considerable heterogeneity in species distribution and complex terrain. The observed fluxes were significantly different than emissions predicted with an emission model using site-specific emission factors and land-cover characteristics. Considering the wide range in reported BVOC emission factors of VOCs for individual vegetation species (more than an order of magnitude), this flux estimation technique is useful for constraining BVOC emission factors used as model inputs.

The Bio-hydro-atmosphere interactions of Energy, Aerosols, Carbon, H2O, Organics & Nitrogen (BEACHON) project seeks to understand the feedbacks and inter-relationships between hydrology, biogenic emissions, carbon assimilation, aerosol properties, clouds and associated feedbacks within water-limited ecosystems. The Manitou Experimental Forest Observatory (MEFO) was established in 2008 by the National Center for Atmospheric Research to address many of the BEACHON research objectives, and it now provides a fixed field site with significant infrastructure. MEFO is a mountainous, semi-arid ponderosa pine-dominated forest site that is normally dominated by clean continental air, but is periodically influenced by anthropogenic sources from Colorado Front Range cities. This article summarizes the past and ongoing research activities at the site, and highlights some of the significant findings that have resulted from these measurements. These activities include: – soil property measurements, – hydrological studies, – measurements of high-frequency turbulence parameters, – eddy covariance flux measurements of water, energy, aerosols and carbon dioxide through the canopy, – biogenic and anthropogenic volatile organic compound emissions and their influence on regional atmospheric chemistry, – aerosol number and mass distributions, – chemical speciation of aerosol particles, – characterization of ice and cloud condensation nuclei, – trace gas measurements, and – model simulations using coupled chemistry and meteorology. In addition to various long-term continuous measurement, three focused measurement campaigns with state-of-the-art instrumentation have taken place since the site was established, and two of these are the subjects of this special issue: BEACHON-ROCS (Rocky Mountain Organic Carbon Study, 2010) and BEACHON-RoMBAS (Rocky Mountain Biogenic Aerosol Study, 2011).

Molecular dynamics simulations of the catalytic subunit of cAMP dependent protein kinase (cAPK) have been performed in an aqueous environment. The relations among the protein hydrogen-bonding network, secondary structural elements, and the internal motions of rigid domains were examined. The values of fluctuations of protein dihedral angles during dynamics show quite distinct maxima in the regions of loops and minima in the regions of alpha-helices and beta-strands. Analyses of conformation snapshots throughout the run show stable subdomains and indicate that these rigid domains are constrained during the dynamics by a stable network of hydrogen bonds. The most stable subdomain during the dynamics was in the small lobe including part of the carboxy-terminal tail. The most significant flexible region was the highly conserved glycine-rich loop between beta strands 1 and 2 in the small lobe. Many of the main chain dihedral angle changes measured in a comparison of the crystallographic structures of "open" and "closed" conformations of cAPK correspond to the highly flexible residues found during dynamics.

Experiments performed at the San Diego (super) computer visualization lab, using a computer graphics model of the standard Shakura-Sunyaev type accretion disk in an X-ray binary system have demonstrated the tendency of these disks to be unstable to the development of warped deformations, when located around an X-ray source of very high luminosity. Experimental determination of the threshold luminosity above which the instability is activated gave 1-10% of Eddington Luminosity, depending on binary parameters. The instability may provide a suitable mechanism for causing accretion disks to tilt out of the binary plane, thereby causing them to start precessing. These results suggest that disk precession may be a very common phenomenon in high luminosity X-ray sources; much more common than suggested by the small number of presently known cases of the precessing disk phenomenon.

The structures of the mirror image (+)- and (-)-trans-anti-adducts of 7,8-dihydroxy-9,10-epoxy-7,8,9,10-tetrahydrobenzo(a)pyrene to guanine N2 have been of great interest because the high biological activity of 7,8-dihydroxy-9,10-epoxy-7,8,9,10-tetrahydrobenzo(a)pyrene in mammalian mutagenesis and tumorigenesis has been attributed to the predominant (+)-trans-anti-adduct. We have carried out new potential energy minimization studies, involving wide-scale conformational searches on small modified DNA subunits, followed by energy-minimized build-up techniques, to generate atomic resolution views of these adducts. These energy-minimized duplex dodecamers were then subjected to 100-ps molecular dynamic simulations with solvent and salt to yield animated molecular structures. The most favored computed structure for the (+)-adduct places the pyrenyl moiety in the B-DNA minor groove, with its long axis directed toward the 5' end of the modified strand, and with a pronounced bend in the helix axis. In the (-)-adduct, there are 2 favored structures. One places the pyrenyl moiety in the minor groove, whereas the other positions it in the major groove; in both cases, the pyrenyl long axis is directed more toward the 3' end of the modified strand, and with much less helix axis bend. Structures with intercalation character computed for these adducts are less preferred. The favored computed structures agree with spectroscopic data on the (+)- and (-)-trans-anti-adducts, whereas recent experimental evidence suggests that cis-adducts assume intercalation-type structures. Perhaps the conformational distinctions elucidated for the (+)- and (-)-trans anti-adducts play a role in their differential tumorigenic properties in mammalian systems.

Eighteen patients had caudate nucleus infarcts (10 left-sided; 8 right-sided). Infarcts extended into the anterior limb of the internal capsule in 9 patients, and also the anterior putamen in 5 patients. Thirteen patients had motor signs, most often a slight transient hemiparesis. Dysarthria was common (11 patients). Cognitive and behavioral abnormalities were frequent, and included abulia (10 patients), agitation and hyperactivity (7 patients), contralateral neglect (3 patients, all right caudate), and language abnormalities (2 patients, both left caudate). The majority of patients had risk factors for penetrating artery disease. Branch occlusion of Heubner's artery, or perforators from the proximal anterior or middle cerebral arteries were the posited mechanism of infarction.

SummaryThe effects of plasmin have been examined because platelets may be exposed to plasmin in vivo and treatment of platelets with plasmin shortens platelet survival. Rabbit plasmin was prepared by urokinase activation of plasminogen immobilized on lysine- Sepharose. Plasmin caused rabbit platelets to aggregate and release the contents of their amine storage granules, but aggregation was slower than in response to ADP or thrombin. EDTA, prostaglandin E1, or creatine phosphate/creatine phosphokinase were inhibitory, but indomethacin was not. Deaggregation did not occur when platelets had been aggregated by a concentration of plasmin that caused extensive release of granule contents. EDTA or prostaglandin E1 caused deaggregation. Low concentrations of ADP and plasmin acted synergistically in causing platelet aggregation. Plasmin decreased the amounts of platelet membrane glycoproteins that stained with periodic acid-Schiff reagent; glycoprotein I was more susceptible than glycoproteins II and III. Concentrations of plasmin that induced the release of amine storage granule contents also released PAS- staining granule gylcoproteins.Platelets incubated with plasmin, washed and resuspended, were not aggregated by ADP, but were aggregated strongly by the combination of fibrinogen and ADP, and bound 125I-fibrinogen to a greater extent than untreated platelets. Platelets preincubated with a high concentration of plasmin were unresponsive to thrombin, but were sometimes aggregated by fibrinogen.Plasmin decreased the buoyant density and increased the median size of platelets. Thus plasmin, as well as ADP and thrombin, may contribute to the density shift observed in platelets from rabbits in which thrombosis and continuous vessel injury have been induced.

n/a

Platelet survival CPS) is shortened in a number of conditions but the mechanisms responsible are unclear. In rabbits, removal of the aortic endothelium or injury of the neointima does not shorten PS. However, induction of thrombi in rabbit aortae with Indwelling cannulae (IDC) shortens FS (IDC 37.0 hr, control 79.6 hr), and Increases the proportion of platelets in the lightest fraction upon straetan density gradient centrifugation. Therefore we examined the effect of agents to which platelets may be exposed during thromboembolism (ADP, thrombin, plasmin) on PS and platelet density. ADP treatnent of washed rabbit platelets did not alter their survival but did increase the proportion in the lightest fraction. Treatment of platelets with thrombin did not shorten PS but increased the proportion in the lightest fraction. Treatment with plasmin in vitro shortened PS (plasmin, 57.6 ± 6.0 hr, control 80.2 ± 4,2 hr) and increased the proportion in the lightest fraction. Thus changes in platelet density are not necessarily associated with changes in PS. Of the factors investigated that are known to be involved in thromboembolism, only plasmin shortened PS. This may be due to its ability to alter major platelet membrane glycoproteins(principally glycoproteins I and II of rabbit platelets).

The effects of plasmin have been examined because platelets may be exposed to plasmin in vivo and treatment of platelets with plasmin shortens platelet survival. Rabbit plasmin was prepared by urokinase activation of plasminogen immobilized on lysine-Sepharose. Plasmin caused rabbit platelets to aggregate and release the contents of their amine storage granules, but aggregation was slower than in response to ADP or thrombin. EDTA, prostaglandin E1, or creatine phosphate/creatine phosphokinase were inhibitory, but indomethacin was not. Deaggregation did not occur when platelets had been aggregated by a concentration of plasmin that caused extensive release of granule contents. EDTA or prostaglandin E1 caused deaggregation. Low concentrations of ADP and plasmin acted synergistically in causing platelet aggregation. Plasmin decreased the amounts of platelet membrane glycoproteins that stained with periodic acid-Schiff reagent; glycoprotein I was more susceptible than glycoprotein II and III. Concentrations of plasmin that induced the release of amine storage granule contents also released PAS-staining granule glycoproteins. Platelets incubated with plasmin, washed and resuspended, were not aggregated by ADP, but were aggregated strongly by the combination of fibrinogen and ADP, and bound 125I-fibrinogen to a greater extent than untreated platelets. Platelets preincubated with a high concentration of plasmin were unresponsive to thrombin, but were sometimes aggregated by fibrinogen. Plasmin decreased the buoyant density and increased the median size of platelets. Thus plasmin, as well as ADP and thrombin, may contribute to the density shift observed in platelets from rabbits in which thrombosis and continuous vessel injury have been induced.

n/a

In connection with an extensive pharmacological and psychological study of antipyretic drugs, the effect of same was tried on the acuity of hearing. Experiments were performed on normal human subjects, and in a few cases on persons suffering with mild deafness. The tests were made, by means of a watch, in a quiet room, with the subject in a sitting position; and all necessary controls were carried out for the elimination of error. In every experiment the normal limit of hearing was first determined; the drug to be studied was then administered by mouth; and the acuity was afterwards tested at definite intervals of time. Only therapeutic doses of the drugs were administered. The following substances were studied: acetanilid, acetphenetidin, antipyrin, pyramidon, lactophenin, salol, aspirin, quinin, sodium salicylate, and “melubrin.” After studying the effects of individual drugs, certain combinations were administered. The following were among the combinations studied: acetanilid plus sodium bicarbonate, a...