Distribution of intracellular and secreted surfactant during postnatal rat lung development

Pulmonary surfactant prevents alveolar collapse via reduction of surface tension. In contrast to human neonates, rats are born with saccular lungs. Therefore, rat lungs serve as a model for investigation of the surfactant system during postnatal alveolar formation. We hypothesized that this process is associated with characteristic structural and biochemical surfactant alterations. We aimed to discriminate changes related to alveolarization from those being either invariable or follow continuous patterns of postnatal changes. Secreted active (mainly tubular myelin (tm)) and inactive (unilamellar vesicles (ulv)) surfactant subtypes as well as intracellular surfactant (lamellar bodies (lb)) in type II pneumocytes (PNII) were quantified before (day (d) 1), during (d 7), at the end of alveolarization (d 14), and after completion of lung maturation (d 42) using electron microscopic methods supplemented by biochemical analyses (phospholipid quantification, immunoblotting for SP-A). Immunoelectron microscopy determined the localization of surfactant protein A (SP-A). (1) At d 1 secreted surfactant was increased relative to d 7-42 and then decreased significantly. (2) Air spaces of neonatal lungs comprised lower fractions of tm and increased ulv, which correlated with low SP-A concentrations in lung lavage fluid (LLF) and increased respiratory rates, respectively. (3) Alveolarization (d 7-14) was associated with decreasing PNII size although volume and sizes of Lb continuously increased. (4) The volume fractions of Lb correlated well with the pool sizes of phospholipids in lavaged lungs. Our study emphasizes differential patterns of developmental changes of the surfactant system relative to postnatal alveolarization.

Upper ocean vertical supply: A neglected primary factor controlling the distribution of neodymium concentrations of open ocean surface waters?

Neodymium (Nd) isotopes are an important geochemical tool to trace the present and past water mass mixing as well as continental inputs. The distribution of Nd concentrations in open ocean surface waters (0�100 m) is generally assumed to be controlled by lateral mixing of Nd from coastal surface currents and by removal through reversible particle scavenging. However, using 228Ra activity as an indicator of coastal water mass influence, surface water Nd concentration data available on key oceanic transects as a whole do not support the above scenario. From a global compilation of available data, we find that more stratified regions are generally associated with low surface Nd concentrations. This implies that upper ocean vertical supply may be an as yet neglected primary factor in determining the basin-scale variations of surface water Nd concentrations. Similar to the mechanism of nutrients supply, it is likely that stratification inhibits vertical supply of Nd from the subsurface thermocline waters and thus the magnitude of Nd flux to the surface layer. Consistently, the estimated required input flux of Nd to the surface layer to maintain the observed concentrations could be nearly two orders of magnitudes larger than riverine/dust flux, and also larger than the model-based estimation on shelf-derived coastal flux. In addition, preliminary results from modeling experiments reveal that the input from shallow boundary sources, riverine input, and release from dust are actually not the primary factors controlling Nd concentrations most notably in the Pacific and Southern Ocean surface waters.

Narrow dust jets in a diffuse gas coma: a natural product of small active regions on comets

Comets often display narrow dust jets but more diffuse gas comae when their eccentric orbits bring them into the inner solar system and sunlight sublimates the ice on the nucleus. Comets are also understood to have one or more active areas covering only a fraction of the total surface active with sublimating volatile ices. Calculations of the gas and dust distribution from a small active area on a comet’s nucleus show that as the gas moves out radially into the vacuum of space it expands tangentially, filling much of the hemisphere centered on the active region. The dust dragged by the gas remains more concentrated over the active area. This explains some puzzling appearances of comets having collimated dust jets but more diffuse gaseous atmospheres. Our test case is 67P/Churyumov–Gerasimenko, the Rosetta mission target comet, whose activity is dominated by a single area covering only 4% of its surface.

Analysis of the erosive effect of different dietary substances and medications

Excessive consumption of acidic drinks and foods contributes to tooth erosion. The aims of the present in vitro study were twofold: (1) to assess the erosive potential of different dietary substances and medications; (2) to determine the chemical properties with an impact on the erosive potential. We selected sixty agents: soft drinks, an energy drink, sports drinks, alcoholic drinks, juice, fruit, mineral water, yogurt, tea, coffee, salad dressing and medications. The erosive potential of the tested agents was quantified as the changes in surface hardness (ΔSH) of enamel specimens within the first 2 min (ΔSH2-0 = SH2 min - SHbaseline) and the second 2 min exposure (ΔSH4-2 = SH4 min - SH2 min). To characterise these agents, various chemical properties, e.g. pH, concentrations of Ca, Pi and F, titratable acidity to pH 7·0 and buffering capacity at the original pH value (β), as well as degree of saturation (pK - pI) with respect to hydroxyapatite (HAP) and fluorapatite (FAP), were determined. Erosive challenge caused a statistically significant reduction in SH for all agents except for coffee, some medications and alcoholic drinks, and non-flavoured mineral waters, teas and yogurts (P < 0·01). By multiple linear regression analysis, 52 % of the variation in ΔSH after 2 min and 61 % after 4 min immersion were explained by pH, β and concentrations of F and Ca (P < 0·05). pH was the variable with the highest impact in multiple regression and bivariate correlation analyses. Furthermore, a high bivariate correlation was also obtained between (pK - pI)HAP, (pK - pI)FAP and ΔSH.

Adsorption behavior of redox-active suppressor additives: Combined electrochemical and STM studies

The redox chemistry and the related surface phase behavior of Safranine (SAF) and Janus Green B (JGB) have been studied by means of cyclic voltammetry in combination with in situ Scanning Tunneling Microscopy using HOPG (Highly Oriented Pyrolytic Graphite) and single crystalline Cu(1 0 0) as model substrates, both revealing different widths of the accessible potential windows. JGB and SAF serve as prototypical heterocyclic suppressor/leveler additives that are used for the metallization of 3D-TSVs (3D Through Silicon Vias) following a classical "leveling" concept. SAF can be considered as the reductive decomposition product of JGB that is formed at the copper/electrolyte interface upon electroplating. Both additives reveal a pronounced pH-dependent redox-chemistry with redox-transitions lying close to or even beyond the anodic limit of the copper potential window. Affected by these redox-processes are in particular the aromatic cores of those heterocycles that can be (quasi)reversibly reduced by a two electron transfer process within the potential window of copper. Therefore we identify the reduced form of those dyes as the active components for the suppressing/leveling effect in copper plating. STM data clearly shows a dye surface phase behavior that is crucially determined by its potential-dependent redox-chemistry. This will be exemplarily discussed for the SAF dye. On chloride-modified Cu(1 0 0) mono-reduced SAF forms a structurally well-defined monolayer of cationic stacking polymers. However, this coupled anion/cation layer reveals only minor suppressing capabilities with respect to the copper dissolution and deposition processes. Complete reduction of the aromatic heterocycle finally leads to the 3D precipitation of hydrophobic reaction products. 3D clusters of this SAF precipitate are discussed as the active structural motif for the suppressing effect of these dyes. (C) 2011 Elsevier Ltd. All rights reserved.

Topographic and age-dependent distribution of subchondral bone density in the elbow joints of clinically normal dogs

OBJECTIVE: To investigate topographic and age-dependent adaptation of subchondral bone density in the elbow joints of healthy dogs by means of computed tomographic osteoabsorptiometry (CTOAM). Animals-42 elbow joints of 29 clinically normal dogs of various breeds and ages. PROCEDURES: Subchondral bone densities of the humeral, radial, and ulnar joint surfaces of the elbow relative to a water-hydroxyapatite phantom were assessed by means of CTOAM. Distribution patterns in juvenile, adult, and geriatric dogs (age, < 1 year, 1 to 8 years, and > 8 years, respectively) were determined and compared within and among groups. RESULTS: An area of increased subchondral bone density was detected in the humerus distomedially and cranially on the trochlea and in the olecranon fossa. The ulna had maximum bone densities on the anconeal and medial coronoid processes. Increased bone density was detected in the craniomedial region of the joint surface of the radius. A significant age-dependent increase in subchondral bone density was revealed in elbow joint surfaces of the radius, ulna, and humerus. Mean subchondral bone density of the radius was significantly less than that of the ulna in paired comparisons for all dogs combined and in adult and geriatric, but not juvenile, dog groups. CONCLUSIONS AND CLINICAL RELEVANCE: An age-dependent increase in subchondral bone density at the elbow joint was revealed. Maximal relative subchondral bone densities were detected consistently at the medial coronoid process and central aspect of the humeral trochlea, regions that are commonly affected in dogs with elbow dysplasia.

Differential distribution of vasa vasorum in different vascular beds in humans

OBJECTIVE: Vasa vasorum (VV) have been implicated to play a role in the pathogenesis of atherosclerosis. This study was designed to describe the distribution of VV density in different vascular beds in humans and to investigate the association between VV density and the known distribution of atherosclerosis in human arteries. METHODS: Forty-two human arteries, harvested at autopsy or after explantation, were analyzed by three-dimensional microscopic-computed tomography (micro-CT). VV density, endothelial-surface-fraction (Sigma VV endothelial-surface-area/vessel-wall-volume) and vascular-area-fraction (Sigma VV area/vessel-wall-area) were calculated for coronary, renal and femoral arteries. Representatively five coronary, renal and femoral arteries were stained for endothelial cells (von Willebrand-Factor), macrophages (CD68), vascular endothelial growth factor (VEGF) and collagen (Sirius Red). RESULTS: Coronary arteries showed a higher VV density compared to renal and femoral arteries (2.12+/-0.26 n/mm(2) versus 0.61+/-0.06 n/mm(2) and 0.66+/-0.11 n/mm(2); P<0.05 for both) as well as a higher endothelial-surface-fraction and vascular-area-fraction. Histology showed a positive correlation between histologically derived VV density and CD68-positive cells/area (r=0.54, P<0.01), VEGF-immunoreactivity/area (r=0.55, P<0.01) and a negative correlation between VV density and collagen I content (r=0.66, P<0.05). CONCLUSION: This micro-CT study highlights a higher VV density in coronary than in peripheral arteries, supporting the relation between VV density and the susceptibility to atherosclerosis in different vascular beds in humans.

The polarized distribution of poly(A+)-mRNA-induced functional ion channels in the Xenopus oocyte plasma membrane is prevented by anticytoskeletal drugs

Foreign mRNA was expressed in Xenopus laevis oocytes. Newly expressed ion currents localized in defined plasma membrane areas were measured using the two-electrode voltage clamp technique in combination with a specially designed chamber, that exposed only part of the surface on the oocytes to channel agonists or inhibitors. Newly expressed currents were found to be unequally distributed in the surface membrane of the oocyte. This asymmetry was most pronounced during the early phase of expression, when channels could almost exclusively be detected in the animal hemisphere of the oocyte. 4 d after injection of the mRNA, or later, channels could be found at a threefold higher density at the animal than at the vegetal pole area. The pattern of distribution was observed to be similar with various ion channels expressed from crude tissue mRNA and from cRNAs coding for rat GABAA receptor channel subunits. Electron microscopical analysis revealed very similar microvilli patterns at both oocyte pole areas. Thus, the asymmetric current distribution is not due to asymmetric surface structure. Upon incubation during the expression period in either colchicine or cytochalasin D, the current density was found to be equal in both pole areas. The inactive control substance beta-lumicolchicine had no effect on the asymmetry of distribution. Colchicine was without effect on the amplitude of the expressed whole cell current. Our measurements reveal a pathway for plasma membrane protein expression endogenous to the Xenopus oocyte, that may contribute to the formation and maintenance of polarity of this highly organized cell.

The spatial distribution of water in the inner coma of Comet 9P/Tempel 1: Comparison between models and observations

The near nucleus coma of Comet 9P/Tempel 1 has been simulated with the 3D Direct Simulation Monte Carlo (DSMC) code PDSC++ (Su, C.-C. [2013]. Parallel Direct Simulation Monte Carlo (DSMC) Methods for Modeling Rarefied Gas Dynamics. PhD Thesis, National Chiao Tung University, Taiwan) and the derived column densities have been compared to observations of the water vapour distribution found by using infrared imaging spectrometer on the Deep Impact spacecraft (Feaga, L.M., A’Hearn, M.F., Sunshine, J.M., Groussin, O., Farnham, T.L. [2007]. Icarus 191(2), 134–145. http://dx.doi.org/10.1016/j.icarus.2007.04.038). Modelled total production rates are also compared to various observations made at the time of the Deep Impact encounter. Three different models were tested. For all models, the shape model constructed from the Deep Impact observations by Thomas et al. (Thomas, P.C., Veverka, J., Belton, M.J.S., Hidy, A., A’Hearn, M.F., Farnham, T.L., et al. [2007]. Icarus, 187(1), 4–15. http://dx.doi.org/10.1016/j.icarus.2006.12.013) was used. Outgassing depending only on the cosine of the solar insolation angle on each shape model facet is shown to provide an unsatisfactory model. Models constructed on the basis of active areas suggested by Kossacki and Szutowicz (Kossacki, K., Szutowicz, S. [2008]. Icarus, 195(2), 705–724. http://dx.doi.org/10.1016/j.icarus.2007.12.014) are shown to be superior. The Kossacki and Szutowicz model, however, also shows deficits which we have sought to improve upon. For the best model we investigate the properties of the outflow.

Characterization of surface winds over the Iberian Peninsula

This work presents a characterization of the surface wind climatology over the Iberian Peninsula (IP). For this objective, an unprecedented observational database has been developed. The database covers a period of 6years (2002–2007) and consists of hourly wind speed and wind direction data recorded at 514 automatic weather stations. Theoriginal observations underwent a quality control process to remove rough errors from the data set. In the first step, the annual and seasonal mean behaviour of the wind field are presented. This analysis shows the high spatial variability of the wind as a result of its interaction with the main orographic features of the IP. In order to simplify the characterization of the wind, a clustering procedure was applied to group the observational sites with similar temporal wind variability. A total of 20 regions are identified. These regions are strongly related to the main landforms of the IP. The wind behaviour of each region, characterized by the wind rose (WR), annual cycle (AC) and wind speed histogram, is explained as the response of each region to the main circulation types (CTs) affecting the IP. Results indicate that the seasonal variability of the synoptic scale is related with intra-annual variability and modulated by local features in the WRs variability. The wind speed distribution not always fit to a unimodal Weibull distribution consequence of interactions at different atmospheric scales. This work contributes to a deeper understanding of the temporal and spatial variability of surface winds. Taken together, the wind database created, the methodology used and the conclusion extracted are a benchmark for future works based on the wind behaviour.

A 49 year hindcast of surface winds over the Iberian Peninsula

The use of hindcast climatic data is quite extended for multiple applications. However, this approach needs the support of a validation process to allow its drawbacks and, therefore, confidence levels to be assessed. In this work, the strategy relies on an hourly wind database resulting from a dynamical downscaling experiment, with a spatial resolution of 10 km, covering the Iberian Peninsula (IP), driven by the ERA40 reanalysis (1959–2001) extended by European Centre for Medium-Range Weather Forecast (ECMWF) analysis (2002–2007) and comprising two main steps. Initially, the skill of the simulation is evaluated comparing the quality-tested observational database (Lorente-Plazas et al., 2014) at local and regional scales. The results show that the model is able to portray the main features of the wind over the IP: annual cycles, wind roses, spatial and temporal variability, as well as the response to different circulation types. In addition, there is a significant added value of the simulation with respect to driving conditions, especially in regions with a complex orography. However, some problems are evident, the major drawback being the systematic overestimation of the wind speed, which is mainly attributed to a missrepresentation of frictional forces. The model skill is also lower along the Mediterranean coast and for the Pyrenees. In a second phase, the high spatio-temporal resolution of the pseudo-real wind database is used to explore the limitations of the observational database. It is shown that missing values do not affect the characterisation of the wind climate over the IP, while the length of the observational period (6 years) is sufficient for most regions, with only a few exceptions. The spatial distribution of the observational sampling schemes should be enhanced to improve the correct assessment of all IP wind regimes, particularly in some mountainous areas.

Size-frequency distribution of boulders ≥7 m on comet 67P/Churyumov-Gerasimenko

Aims. We derive for the first time the size-frequency distribution of boulders on a comet, 67P/Churyumov-Gerasimenko (67P), computed from the images taken by the Rosetta/OSIRIS imaging system. We highlight the possible physical processes that lead to these boulder size distributions. Methods. We used images acquired by the OSIRIS Narrow Angle Camera, NAC, on 5 and 6 August 2014. The scale of these images (2.44−2.03 m/px) is such that boulders ≥7 m can be identified and manually extracted from the datasets with the software ArcGIS. We derived both global and localized size-frequency distributions. The three-pixel sampling detection, coupled with the favorable shadowing of the surface (observation phase angle ranging from 48° to 53°), enables unequivocally detecting boulders scattered all over the illuminated side of 67P. Results. We identify 3546 boulders larger than 7 m on the imaged surface (36.4 km2), with a global number density of nearly 100/km2 and a cumulative size-frequency distribution represented by a power-law with index of −3.6 +0.2/−0.3. The two lobes of 67P appear to have slightly different distributions, with an index of −3.5 +0.2/−0.3 for the main lobe (body) and −4.0 +0.3/−0.2 for the small lobe (head). The steeper distribution of the small lobe might be due to a more pervasive fracturing. The difference of the distribution for the connecting region (neck) is much more significant, with an index value of −2.2 +0.2/−0.2. We propose that the boulder field located in the neck area is the result of blocks falling from the contiguous Hathor cliff. The lower slope of the size-frequency distribution we see today in the neck area might be due to the concurrent processes acting on the smallest boulders, such as i) disintegration or fragmentation and vanishing through sublimation; ii) uplifting by gas drag and consequent redistribution; and iii) burial beneath a debris blanket. We also derived the cumulative size-frequency distribution per km2 of localized areas on 67P. By comparing the cumulative size-frequency distributions of similar geomorphological settings, we derived similar power-law index values. This suggests that despite the selected locations on different and often opposite sides of the comet, similar sublimation or activity processes, pit formation or collapses, as well as thermal stresses or fracturing events occurred on multiple areas of the comet, shaping its surface into the appearance we see today.