Effects of biaxial deformation on pulmonary artery endothelial cells

An apparatus has been designed to subject vascular cells grown on a compliant substrate in vitro to uniform, quantifiable levels of biaxial deformation. The system described can be controlled with respect to strain level, rate, and frequency to mimic the pulsatile force to which vascular cells are exposed in vivo under both physiologic and pathologic conditions. In the experiments presented here, bovine pulmonary artery endothelial cells were grown on a substrate of segmented polyurethane urea (Mitrathane). Cell growth and morphology on this substrate were compared with those of cells grown on standard tissue culture polystyrene with no difference noted between the two substrates. Primary cultures of pulmonary artery endothelial cells were seeded onto Mitrathane, which was then subjected to cyclic biaxial deformation-producing strains of 0.78%, 1.76%, 4.9%, or 12.5% at a frequency of 1 sec-1 and a duty cycle of 0.5 sec-1 for 7 h. Cells subjected to deformations generating strains of either 4.9% or 12.5% secreted significantly less fibronectin than nondeformed cells. Similar results were obtained in experiments using cloned pulmonary artery endothelial cells on Mitrathane subjected to the 4.9% strain; however, total protein synthesis was increased. Cell viability and DNA synthesis were not affected by cyclic biaxial deformation in these experiments.     

Lucky rugose corals on crinoid stems: unusual examples of subepidermal epizoans from the Devonian of Morocco

Berkowski, B & Klug, C. 2011: Lucky rugose corals on crinoid stems: unusual examples of subepidermal epizoans from the Devonian of Morocco. Lethaia, Vol. 45, pp. 24–33. In the fossil record, evidence for true epizoans, i.e. living animals inhabiting other living host‐animals, is rather rare. A host reaction is usually needed to proof the syn vivo‐settling of the epizoan. Herein, we provide a first report of such an epizoan biocoenosis from various strata of the Early Devonian of Hamar Laghdad, the world‐renowned Moroccan mud‐mound locality. In this case, solitary rugose corals settled as larvae on crinoid stems, perhaps at a spot where the epidermis was missing for some reason (injury, disease). Both the crinoid and the coral began to grow around each other. By doing so, the affected crinoid columnals formed a swelling, where ultimately only an opening slightly larger than the coral orifice remained. We discuss both macroecological and small‐scale synecological aspects of this biocoenosis. The coral profited from its elevated home because it reached into more rapid currents providing the polyp with more food than at the densely populated seafloor, which was probably covered by a coral‐meadow around the mounds and hydrothermal vents. □Corals, crinoids, Early Devonian, epizoans, Morocco, Rugosa.     

Meta-analysis of the literature on diagnostic accuracy of SPECT in parkinsonian syndromes

Background  

Parkinson's disease (PD) is the second most common neurodegenerative disorder. One of the most widely used techniques to diagnose PD is a Single Photon Emission Computer Tomography (SPECT) scan to visualise the integrity of the dopaminergic pathways in the brain. Despite this there remains some discussion on the value of SPECT in the differential diagnosis of PD. We did a meta-analysis of all the existing literature on the diagnostic accuracy of both pre- and post-synaptic SPECT imaging in the differential diagnosis of PD.     

An ultrastructural study of adhesive junctions in reaggregates of unincubated chick embryos.

Cell suspensions obtained by the dissociation of unincubated chick embryo blastoderms were allowed to reaggregate on a gyratory shaker for 24-48 hours. The reaggregates which form during this period consist of an inner phase of tightly packed cohesive cells surrounded by an external phase of loosely packed cells. This sorted out arrangement achieves its definitive form between 24 and 48 hours of rotation culture. It was determined that the external phase consists of primitive ectoderm and that the internal phase consists of primitive endoderm. Both 24- and 48-hour reaggregates were examined in the electron microscope and observations were directed to areas of close membrane apposition between cells. In 48-hour reaggregates, primitive endoderm cells were joined by many specialized junctions (desmosomes). The formation of desmosomes in reaggregates of dissociated unincubated chick embryo cells was correlated with the sorting out process.     

Above‐ and belowground linkages in Sphagnum peatland: climate warming affects plant‐microbial interactions

Peatlands contain approximately one third of all soil organic carbon (SOC). Warming can alter above‐ and belowground linkages that regulate soil organic carbon dynamics and C‐balance in peatlands. Here we examine the multiyear impact of in situ experimental warming on the microbial food web, vegetation, and their feedbacks with soil chemistry. We provide evidence of both positive and negative impacts of warming on specific microbial functional groups, leading to destabilization of the microbial food web. We observed a strong reduction (70%) in the biomass of top‐predators (testate amoebae) in warmed plots. Such a loss caused a shortening of microbial food chains, which in turn stimulated microbial activity, leading to slight increases in levels of nutrients and labile C in water. We further show that warming altered the regulatory role of Sphagnum‐polyphenols on microbial community structure with a potential inhibition of top predators. In addition, warming caused a decrease in Sphagnum cover and an increase in vascular plant cover. Using structural equation modelling, we show that changes in the microbial food web affected the relationships between plants, soil water chemistry, and microbial communities. These results suggest that warming will destabilize C and nutrient recycling of peatlands via changes in above‐ and belowground linkages, and therefore, the microbial food web associated with mosses will feedback positively to global warming by destabilizing the carbon cycle. This study confirms that microbial food webs thus constitute a key element in the functioning of peatland ecosystems. Their study can help understand how mosses, as ecosystem engineers, tightly regulate biogeochemical cycling and climate feedback in peatlands     

Palaeoenvironment and taphonomy of a Late Jurassic (Late Tithonian) Lagerstätte from central Poland

A rich assemblage of exceptionally preserved marine and terrestrial fossils occurs in fine‐grained limestones in the upper part of the Late Tithonian (Middle Volgian) shallowing upward carbonate sequence in Central Poland. The richest horizon, a deposit known locally as the Corbulomima horizon, is named after the shallow burrowing suspension feeding bivalve Corbulomima obscura, moulds of which occur in densities of up to 500 per square metre on some bedding planes. The fauna in this bed also includes organic and phosphatic remains of a wide range of other creatures including the exuviae of limulids and decapods, disarticulated fish skeletons and rare isolated pterosaur bones and teeth. There are also perfectly preserved dragonfly wings and beetle exoskeletons. The average stable carbon and oxygen isotope values for ostracod shells and fine‐grained sediment from this horizon suggest precipitation of the calcium carbonate from warm seawater of normal marine salinity. The carbonate sediments overlying the fossiliferous horizon have been interpreted as nearshore to shoreface facies. These pass abruptly into coarse reworked intraclastic sediments interpreted as possible tsunami or storm surge over‐wash deposits. The clasts in this deposit have more positive oxygen isotope values than those in the underlying limestone, which may indicate that they were lithified in a slightly more evaporative, perhaps intertidal, setting. The succession terminates with silicified fine‐grained limestones likely to have formed in extremely shallow lagoonal environments. In contrast with the Solnhofen limestones of Lower Tithonian age in south‐central Germany the Corbulomima horizon is interpreted as a transitional deposit formed in a shallow marine setting by rapid burial with elements of both Konservat‐ and Konzentrat‐Lagerstätte preservation. □Konzentrat and Konservat‐Lagerstätte, Taphonomy, Palaeoenvironment, Paleogeography, Late Jurassic, Poland.     

Geographic and topographic determinants of local FMD transmission applied to the 2001 UK FMD epidemic

Background

Models of Foot and Mouth Disease (FMD) transmission have assumed a homogeneous landscape across which Euclidean distance is a suitable measure of the spatial dependency of transmission. This paper investigated features of the landscape and their impact on transmission during the period of predominantly local spread which followed the implementation of the national movement ban during the 2001 UK FMD epidemic. In this study 113 farms diagnosed with FMD which had a known source of infection within 3 km (cases) were matched to 188 control farms which were either uninfected or infected at a later timepoint. Cases were matched to controls by Euclidean distance to the source of infection and farm size. Intervening geographical features and connectivity between the source of infection and case and controls were compared.

Results

Road distance between holdings, access to holdings, presence of forest, elevation change between holdings and the presence of intervening roads had no impact on the risk of local FMD transmission (p > 0.2). However the presence of linear features in the form of rivers and railways acted as barriers to FMD transmission (odds ratio = 0.507, 95% CIs = 0.297,0.887, p = 0.018).

Conclusion

This paper demonstrated that although FMD spread can generally be modelled using Euclidean distance and numbers of animals on susceptible holdings, the presence of rivers and railways has an additional protective effect reducing the probability of transmission between holdings.

     

Comparison of the intracellular lipids of cultured vascular endothelial cells and fibroblasts

Summary The lipids of human umbilical vein endothelial cells, calf aortic endothelial cells and foreskin fibroblasts have been compared. Cell cultures were established, and, upon confluency, the lipids were extracted and analyzed with respect to total lipid content, classes of lipids and total lipid fatty acid composition. The total quantity of lipid per milligram protein found in both human umbilical vein endothelium and calf aorta endothelium was similar to that found in fibroblasts grown in similar medium. Both types of endothelium contained the same major neutral lipid classes as fibroblasts, although they contained more phospholipid than did fibroblasts. The fatty acid composition of the three cells examined was influenced by cell type as well as the type of serum in the culture medium. This work was supported by PHS Grants HL16058, HL19638, AM14626 and HL18827.