Flow correlated percolation during vascular network formation in tumors

A theoretical model based on the molecular interactions between a growing tumor and a dynamically evolving blood vessel network describes the transformation of the regular vasculature in normal tissues into a highly inhomogeneous tumor specific capillary network. The emerging morphology, characterized by the compartmentalization of the tumor into several regions differing in vessel density, diameter and necrosis, is in accordance with experimental data for human melanoma. Vessel collapse due to a combination of severely reduced blood flow and solid stress exerted by the tumor, leads to a correlated percolation process that is driven towards criticality by the mechanism of hydrodynamic vessel stabilization.Comment: 4 pages, 3 figures (higher resolution at http://www.uni-saarland.de/fak7/rieger/HOMEPAGE/flow.eps

Comparative haemodynamic studies of resting and active skeletal muscle in anaesthetised rats: role of nitric oxide

Our previous studies have indicated that nitric oxide takes part in the basal regulation of vascular tone in skeletal muscle. The purpose of this study was to investigate whether nitric oxide has a role in the active hyperaemic response of a working muscle in a resting subject. Haemodynamic effects of nitric oxide synthase (NOS) inhibition (L-NAME, 10 mg/kg/30 min iv. infusion) were determined simultaneously in the resting m. quadriceps femoris and in the working (breathing) m. rectus abdominis in anaesthetised rats (86Rb accumulation technique). L-NAME increased blood pressure and total peripheral resistance (TPR) while it decreased cardiac output. Blood flow (BF) decreased and vascular resistance (VR) increased both in resting (BF: 8.91±1.97→5.92±2.59 ml/min/100 g, p<0.05; VR: 106±29.9→ 212±113 R, p<0.01) and working (BF: 17.0±4.78→6.93±2.15 ml/min/100g, p<0.001; VR: 57.0±18.5→160±56.7 R, p<0.01) muscle following NOS inhibition, but the percentile change of BF was higher in the working muscle (59%) than in the resting one (34%, p0.001). There was a positive correlation between the cardiac output and the blood flow of the resting muscle with or without L-NAME administration, but blood flow of the working muscle failed to have any correlation with the cardiac output in control animals. However, L-NAME administration decreased both the cardiac output and the blood flow and similarly to the resting muscle a positive correlation was found. In conclusion, the haemodynamic effects of NOS inhibition are higher in working muscle than in the resting one: the nitric oxide may have important role in vasodilatation during muscle activity

Evaluating alternative mowing regimes for conservation management of Central European mesic hay meadows: A field experiment

<p>Conservation status of hay meadows highly depends on their management. The main goal of this study was to assess the efficiency of different mowing regimes in maintenance of plant species richness and diversity of mesic hay meadows. The field experiment was carried out on a species rich, mesic hay meadow in Western Hungary. We evaluated the effects of four alternative types of management on the plant community after 7 years of continuous treatment: (1) mowing twice a year, typical traditional management, (2) mowing once a year in May, most practised currently by local farmers, (3) mowing once a year in September, often proposed for conservation management and (4) abandonment of mowing. Traditional mowing resulted in significantly higher number and higher diversity of vascular plant species than other mowing regimes. Mowing twice a year was the only efficient way to control the spread of the invasive <i>Solidago gigantea,</i> and mowing in September was more successful in it than mowing in May. We conclude that the traditional mowing regime is the most suitable to maintain botanical diversity of mesic hay meadows; however, other regimes should also be considered if certain priority species are targeted by conservation.</p

Analysis of stop-gain and frameshift variants in human innate immunity genes.

Loss-of-function variants in innate immunity genes are associated with Mendelian disorders in the form of primary immunodeficiencies. Recent resequencing projects report that stop-gains and frameshifts are collectively prevalent in humans and could be responsible for some of the inter-individual variability in innate immune response. Current computational approaches evaluating loss-of-function in genes carrying these variants rely on gene-level characteristics such as evolutionary conservation and functional redundancy across the genome. However, innate immunity genes represent a particular case because they are more likely to be under positive selection and duplicated. To create a ranking of severity that would be applicable to innate immunity genes we evaluated 17,764 stop-gain and 13,915 frameshift variants from the NHLBI Exome Sequencing Project and 1,000 Genomes Project. Sequence-based features such as loss of functional domains, isoform-specific truncation and nonsense-mediated decay were found to correlate with variant allele frequency and validated with gene expression data. We integrated these features in a Bayesian classification scheme and benchmarked its use in predicting pathogenic variants against Online Mendelian Inheritance in Man (OMIM) disease stop-gains and frameshifts. The classification scheme was applied in the assessment of 335 stop-gains and 236 frameshifts affecting 227 interferon-stimulated genes. The sequence-based score ranks variants in innate immunity genes according to their potential to cause disease, and complements existing gene-based pathogenicity scores. Specifically, the sequence-based score improves measurement of functional gene impairment, discriminates across different variants in a given gene and appears particularly useful for analysis of less conserved genes

Cut mowing and grazing effects with grey cattle on plant species composition in case of Pannon wet grasslands

Examined area can be found at Balaton Uplands National Park (Hungary). 5 sample areas were examined in Badacsonytördemic: 1: 32 hectare under-grazed pasture, 2: 38 hectare overgrazed pasture, 3: 34 hectare hayfield, 4: trampled area, 5: beaten track. Livestock population was 118 in the monitored pastures. Sampling was executed along five 52m long circular transects, within 5cm × 5cm interlocking quadrates. Based on the data we can state that the curve of the drinking area was the highest of speciesarea examinations however weed appeared because of degradation which provided more species. According to species-area examinations overgrazed areas were richer in species then other examined areas. Based on diversity data drinking area considered degraded, while meadow and overgrazed areas was considered as proper state. Diversity of meadow was larger, but dominance of economically useful species was smaller. The amount of less valuable species – Carex hirta – increased