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101.
Hemodynamic stress in lateral saccular aneurysms 总被引:7,自引:0,他引:7
The flow velocities in glass and silastic lateral aneurysm models were quantitatively measured with the non-invasive laser Doppler method. The influences of the elasticity of the wall, the pulse wave and the properties of the perfusion medium on the intra-aneurysmal circulation were investigated. As shown previously, the inflow into the aneurysm arose from the downstream lip and was directed toward the center of the fundus. Backflow to the parent vessel took place along the walls of the fundus. With non-pulsatile perfusion, flow velocities in the center of the standardized aneurysms varied between 0.4 and 2% of the maximum velocity in the parent vessel. With pulsatile perfusion, flow velocities in the center of the fundus ranged between 8 and 13% of the flow velocity in the axis of the parent vessel. Flow velocities in the aneurysms were slower with a polymer suspension with blood-like properties compared to a glycerol/water solution. Flow velocity measurements near the aneurysmal wall allowed the estimation of the shear stresses at critical locations. The maximum shear stresses at the downstream lip of the aneurysm were in the range of the stresses measured at the flow divider of an arterial bifurcation. The present results suggest that in human saccular aneurysms intra-aneurysmal flow and shear stress on the wall are directly related to the pulsatility of perfusion, i.e. the systolic/diastolic pressure difference and that the tendency to spontaneous thrombosis depends on the viscoelastic properties of the blood, namely the hematocrit. 相似文献
102.
103.
AMÉLIE VANTAUX SHARON SCHILLEWAERT THOMAS PARMENTIER WIM VAN DEN ENDE JOHAN BILLEN TOM WENSELEERS 《Ecological Entomology》2015,40(5):511-517
1. The aphid Aphis fabae (Scopoli) is facultatively tended by Lasius niger (Linnaeus) ants. Previously, we found that A. fabae colonies can be made up of several clones, and that clones display significant differences in the composition of their honeydew sugars, especially in the amount of the ant attractant sugar melezitose that they produce. 2. These clonal differences could greatly impact the strength of the mutualistic interaction with ants as well as the aphids' fitness. 3. Hence, the aim of this study was to compare the fitness of different A. fabae clones that differed in their melezitose secretion, and whether or not they were tended by ants. 4. Individual fitness indices, colony growth, and alate production of single‐clone aphid colonies were analysed. 5. The results demonstrate that the fitness consequences of ant attendance critically depend on an interaction between levels of melezitose production. In particular, we show that high‐melezitose secreting clones produce fewer alates and hence might have a lower dispersal ability in the presence of ants. 6. Furthermore, these data confirm previous evidence that ant attendance is costly and results in the production of fewer apterae. 相似文献
104.
105.
106.
Rusznyák A Szabó G Pollák B Vágány V Palatinszky M 《Acta microbiologica et immunologica Hungarica》2007,54(4):339-352
From reed biofilm samples of Kelemen-szék (Kiskunság National Park, KNP) and Nagy-Vadas (Hortobágy National Park, HNP) altogether 260 bacterial isolates were gained after serial dilutions and plating onto different media. Following a primary selection 164 strains were investigated by "traditional" phenotypic tests and clustered by numerical analysis. Fifty-six representative strains were selected to ARDRA and 16S rDNA sequence analysis for identification. Strains were identified as members of genera Agrobacterium, Paracoccus, Halomonas, Pseudomonas, Bacillus, Planococcus and Nesterenkonia. The species diversity was also investigated by a cultivation independent method. A clone library was constructed using the community DNA isolated from the biofilm sample of Kelemen-szék. Screening of the 140 bacterial clones resulted in 45 different ARDRA groups. Sequence analysis of the representatives revealed a great phylogenetic diversity. A considerable majority of the clones was affiliated with uncultured bacterial clones (with sequence similarity between 93 and 99%) originating from diverse environmental samples (for example salt marshes, compost or wastewater treatment plants). The DNA sequences of other clones showed the presence of genera Flavobacterium, Sphingobacterium, Pseudomonas and Agrobacterium. 相似文献
107.
AM Fietta AM Bardoni R Salvini I Passadore M Morosini L Cavagna V Codullo E Pozzi F Meloni C Montecucco 《Arthritis research & therapy》2007,8(6):R160
Lung fibrosis is a major cause of mortality and morbidity in systemic sclerosis (SSc). However, its pathogenesis still needs
to be elucidated. We examined whether the alteration of certain proteins in bronchoalveolar lavage fluid (BALF) might have
a protective or a causative role in the lung fibrogenesis process. For this purpose we compared the BALF protein profile obtained
from nine SSc patients with lung fibrosis (SScFib+) with that obtained from six SSc patients without pulmonary fibrosis (SScFib-) by two-dimensional gel electrophoresis (2-DE). Only spots and spot-trains that were consistently expressed in a different
way in the two study groups were taken into consideration. In total, 47 spots and spot-trains, corresponding to 30 previously
identified proteins in human BALF, showed no significant variation between SScFib+ patients and SScFib- patients, whereas 24 spots showed a reproducible significant variation in the two study groups. These latter spots corresponded
to 11 proteins or protein fragments, including serum albumin fragments (13 spots), 5 previously recognized proteins (7 spots),
and 4 proteins (3 spots) that had not been previously described in human BALF maps, namely calumenin, cytohesin-2, cystatin
SN, and mitochondrial DNA topoisomerase 1 (mtDNA TOP1). Mass analysis did not determine one protein-spot. The two study groups
revealed a significant difference in BALF protein composition. Whereas levels of glutathione S-transferase P (GSTP), Cu–Zn
superoxide dismutase (SOD) and cystatin SN were downregulated in SScFib+ patients compared with SScFib- patients, we observed a significant upregulation of α1-acid glycoprotein, haptoglobin-α chain, calgranulin (Cal) B, cytohesin-2,
calumenin, and mtDNA TOP1 in SScFib+ patients. Some of these proteins (GSTP, Cu–Zn SOD, and cystatin SN) seem to be involved in mechanisms that protect lungs
against injury or inflammation, whereas others (Cal B, cytohesin-2, and calumenin) seem to be involved in mechanisms that
drive lung fibrogenesis. Even if the 2-DE analysis of BALF did not provide an exhaustive identification of all BALF proteins,
especially those of low molecular mass, it allows the identification of proteins that might have a role in lung fibrogenesis.
Further longitudinal studies on larger cohorts of patients will be necessary to assess their usefulness as predictive markers
of disease. 相似文献
108.
Rens W O'Brien PC Grützner F Clarke O Graphodatskaya D Tsend-Ayush E Trifonov VA Skelton H Wallis MC Johnston S Veyrunes F Graves JA Ferguson-Smith MA 《Genome biology》2007,8(11):R243-21
Background
Sex-determining systems have evolved independently in vertebrates. Placental mammals and marsupials have an XY system, birds have a ZW system. Reptiles and amphibians have different systems, including temperature-dependent sex determination, and XY and ZW systems that differ in origin from birds and placental mammals. Monotremes diverged early in mammalian evolution, just after the mammalian clade diverged from the sauropsid clade. Our previous studies showed that male platypus has five X and five Y chromosomes, no SRY, and DMRT1 on an X chromosome. In order to investigate monotreme sex chromosome evolution, we performed a comparative study of platypus and echidna by chromosome painting and comparative gene mapping.Results
Chromosome painting reveals a meiotic chain of nine sex chromosomes in the male echidna and establishes their order in the chain. Two of those differ from those in the platypus, three of the platypus sex chromosomes differ from those of the echidna and the order of several chromosomes is rearranged. Comparative gene mapping shows that, in addition to bird autosome regions, regions of bird Z chromosomes are homologous to regions in four platypus X chromosomes, that is, X1, X2, X3, X5, and in chromosome Y1.Conclusion
Monotreme sex chromosomes are easiest to explain on the hypothesis that autosomes were added sequentially to the translocation chain, with the final additions after platypus and echidna divergence. Genome sequencing and contig anchoring show no homology yet between platypus and therian Xs; thus, monotremes have a unique XY sex chromosome system that shares some homology with the avian Z. 相似文献109.
Background
It is widely accepted that genetic regulatory systems are 'modular', in that the whole system is made up of smaller 'subsystems' corresponding to specific biological functions. Most attempts to identify modules in genetic regulatory systems have relied on the topology of the underlying network. However, it is the temporal activity (dynamics) of genes and proteins that corresponds to biological functions, and hence it is dynamics that we focus on here for identifying subsystems. 相似文献110.
Ana Paula F Trombone Celio L Silva Luciana P Almeida Rogerio S Rosada Karla M Lima Constance Oliver Maria C Jamur Arlete AM Coelho-Castelo 《Genetic vaccines and therapy》2007,5(1):1-8