The non-Newtonian rheology of dilute colloidal suspensions

The non-Newtonian rheology is calculated numerically to second order in the volume fraction in steady simple shear flows for Brownian hard spheres in the presence of hydrodynamic and excluded volume interactions. Previous analytical and numerical results for the low-shear structure and rheology are confirmed, demonstrating that the viscosity shear thins proportional to Pe2, where Pe is the dimensionless shear rate or Péclet number, owing to the decreasing contribution of Brownian forces to the viscosity. In the large Pe limit, remnants of Brownian diffusion balance convection in a boundary-layer in the compressive region of the flow. In consequence, the viscosity shear thickens when this boundary-layer coincides with the near-contact lubrication regime of the hydrodynamic interaction. Wakes are formed at large Pe in the extensional zone downstream from the reference particle, leading to broken symmetry in the pair correlation function. As a result of this asymmetry and that in the boundary-layer, finite normal stress differences are obtained as well as positive departures in the generalized osmotic pressure from its equilibrium value. The first normal stress difference changes from positive to negative values as Pe is increased when the hard-sphere limit is approached. This unusual effect is caused by the hydrodynamic lubrication forces that maintain particles in close proximity well into the extensional quadrant of the flow. The study demonstrates that many of the non-Newtonian effects observed in concentrated suspensions by experiments and by Stokesian dynamics simulations are present also in dilute suspensions

Seasonal overview of beef meat quality in a small-scale slaughterhouse

The objective of this study was to investigate a possible relationship between blood parameters related to animal welfare and defined beef meat quality characteristics during winter and summer seasons in one small-scale slaughterhouse. At exsanguination, blood samples were collected, and serum concentrations for total proteins (TP), albumin and C-reactive protein (CRP) were evaluated. After 24 h of chilling, ultimate pH was measured and meat samples were used for drip loss and cooking loss determination. Dehydration was not observed during seasons, while elevated concentrations of TP accompanied by higher CRP values pointed to summer as a more stressful season. Analysing the meat quality parameters, it was observed that during the two seasons, ultimate pH values were in the range for normal meat acidification, but values for drip and cooking loss were significantly increased during the summer season. In conclusion, CRP could be used as potential biomarker for beef meat quality estimation, in the first instance drip loss and ultimate pH

Seasonal changes in photosynthetic rate and pigment content in two populations of the monotypic Balkan serpentine endemic Halacsya sendtneri

Halacsya sendtneri (Boiss.) Dorfl. is an obligate serpentine palaeoendemic of the Balkan Peninsula. It is able to maintain a favourable magnesium:calcium (Mg:Ca) ratio throughout its root and shoot, and grow in serpentine habitats with different microclimate conditions. Seasonal variation of leaf chlorophyll and carotenoid contents showed a steep decline right after the spring period, which was most probably caused by the drought imposed on the plants on the shallow serpentine soil. However, the in situ photosynthetic rate remained stable throughout the spring and summer period. Prolonged photosynthetic activity enables this species an investment into root development and sustainable survival in the harsh soils of the habitats it occupies

Fetal cystic hygroma associated with terminal 2p25.1 duplication and terminal 3p25.3 deletion: Cytogenetic, fluorescent in situ hybridization and microarray familial characterization of two different chromosomal structural rearrangements

We report a prenatally diagnosed case of partial trisomy 2p and partial monosomy 3p, resulting from unbalanced translocation (2;3)(p25.1;p25.3) of paternal origin. Parents were non consanguineous Caucasians, with familial history of recurrent miscarriages on the father’s side. Detailed sonographic examination of the fetus showed a septated cystic hygroma measuring 6 mm at 13 weeks’ gestation. Karyotyping and fluorescent in situ hybridization (FISH) analysis of cultured amniotic fluid cells revealed an unbalanced translocation der(3)t(2;3)(p25.1; p25.3) and apparently balanced inv(3)(p13p25.3) in a fetus. Parental cytogenetic evaluation using karyotyping and FISH analysis showed the presence of both a balanced translocation and a paracentric inversion in father t(2;3) (p25.1;p25.3) inv(3)(p13p25.3). Microarray analysis showed a 11.6 Mb deletion at 3p26.3-p25.3 and duplication of 10.5 Mb at the 2p25.3-p25 region. The duplicated region at 2p25.1p25.3 contains 45 different genes, where 12 are reported as OMIM morbid genes with different phenotypical implications. The deleted region at 3p26.3-p25.3 contains 65 genes, out of which 27 are OMIM genes

Physiological Tolerance Mechanisms of Serpentine Tolerant Plants from Serbia

Serpentine (ultramafic) soils are extremely stressful environments for plant growth due to macronutrient deficiency (N, P, K, Ca), macronutrient toxicity (Mg; extremely high Mg:Ca ratio), and micronutrient toxicity (Mn, Fe, Ni, Cu, Zn), as well as toxicity of other heavy metals (Al, Cr, Co). Serpentine soils are also often shallow, rocky, and susceptible to drought. As a result of extreme adverse physical and chemical conditions, serpentine soils support a high proportion of endemic plant species that are adapted to their harsh environment. We analysed root, stem, and leaf tissue element concentrations (Ca, Mg, Al, Mn, Fe, Ni, Cu, and Zn) of Halacsya sendtneri (Boraginaceae; strict serpentine endemic), Cheilanthes marantae (Pteridaceac; broad serpentine endemic/strong indicator), and Seseli rigidum (Apiaccac; weak serpentine indicator/indifferent) growing on serpentine and limestone in Serbia. Element bioaccumulation factor was calculated as the ratio of plant tissue clement concentration to soil plant-available element concentration. Tissue concentrations of Ca and Mg for H. sendtneri and S. rigidum indicate that the species selectively uptake and translocatc Ca to leaves, relative to Mg, to maintain adequate tissue Mg:Ca ratio. C. marantae did not exhibit selective Ca uptake or translocation, but did exhibit Mg sequestration in roots. Heavy metal exclusion and sequestration were the primary physiological tolerance mechanisms conveying serpentine tolerance in the three species. S. rigidum exhibited divergence into serpentine tolerant and limestone tolerant ecotypes, presenting a useful model species for further studies of physiological adaptation to chemically extreme soils

Physiological Tolerance Mechanisms of Serpentine Tolerant Plants from Serbia

Serpentine (ultramafic) soils are extremely stressful environments for plant growth due to macronutrient deficiency (N, P, K, Ca), macronutrient toxicity (Mg; extremely high Mg:Ca ratio), and micronutrient toxicity (Mn, Fe, Ni, Cu, Zn), as well as toxicity of other heavy metals (Al, Cr, Co). Serpentine soils are also often shallow, rocky, and susceptible to drought. As a result of extreme adverse physical and chemical conditions, serpentine soils support a high proportion of endemic plant species that are adapted to their harsh environment. We analysed root, stem, and leaf tissue element concentrations (Ca, Mg, Al, Mn, Fe, Ni, Cu, and Zn) of Halacsya sendtneri (Boraginaceae; strict serpentine endemic), Cheilanthes marantae (Pteridaceac; broad serpentine endemic/strong indicator), and Seseli rigidum (Apiaccac; weak serpentine indicator/indifferent) growing on serpentine and limestone in Serbia. Element bioaccumulation factor was calculated as the ratio of plant tissue clement concentration to soil plant-available element concentration. Tissue concentrations of Ca and Mg for H. sendtneri and S. rigidum indicate that the species selectively uptake and translocatc Ca to leaves, relative to Mg, to maintain adequate tissue Mg:Ca ratio. C. marantae did not exhibit selective Ca uptake or translocation, but did exhibit Mg sequestration in roots. Heavy metal exclusion and sequestration were the primary physiological tolerance mechanisms conveying serpentine tolerance in the three species. S. rigidum exhibited divergence into serpentine tolerant and limestone tolerant ecotypes, presenting a useful model species for further studies of physiological adaptation to chemically extreme soils

Physiological Tolerance Mechanisms of Serpentine Tolerant Plants from Serbia

Serpentine (ultramafic) soils are extremely stressful environments for plant growth due to macronutrient deficiency (N, P, K, Ca), macronutrient toxicity (Mg; extremely high Mg:Ca ratio), and micronutrient toxicity (Mn, Fe, Ni, Cu, Zn), as well as toxicity of other heavy metals (Al, Cr, Co). Serpentine soils are also often shallow, rocky, and susceptible to drought. As a result of extreme adverse physical and chemical conditions, serpentine soils support a high proportion of endemic plant species that are adapted to their harsh environment. We analysed root, stem, and leaf tissue element concentrations (Ca, Mg, Al, Mn, Fe, Ni, Cu, and Zn) of Halacsya sendtneri (Boraginaceae; strict serpentine endemic), Cheilanthes marantae (Pteridaceac; broad serpentine endemic/strong indicator), and Seseli rigidum (Apiaccac; weak serpentine indicator/indifferent) growing on serpentine and limestone in Serbia. Element bioaccumulation factor was calculated as the ratio of plant tissue clement concentration to soil plant-available element concentration. Tissue concentrations of Ca and Mg for H. sendtneri and S. rigidum indicate that the species selectively uptake and translocatc Ca to leaves, relative to Mg, to maintain adequate tissue Mg:Ca ratio. C. marantae did not exhibit selective Ca uptake or translocation, but did exhibit Mg sequestration in roots. Heavy metal exclusion and sequestration were the primary physiological tolerance mechanisms conveying serpentine tolerance in the three species. S. rigidum exhibited divergence into serpentine tolerant and limestone tolerant ecotypes, presenting a useful model species for further studies of physiological adaptation to chemically extreme soils

Evidence of an Annexin A4 mediated plasma membrane repair response to biomechanical strain associated with glaucoma pathogenesis

Glaucoma is a common neurodegenerative blinding disease that is closely associated with chronic biomechanical strain at the optic nerve head (ONH). Yet, the cellular injury and mechanosensing mechanisms underlying the resulting damage have remained critically unclear. We previously identified Annexin A4 (ANXA4) from a proteomic analyses of human ONH astrocytes undergoing pathological biomechanical strain that mimics glaucomatous conditions. Annexins are a family of calcium-dependent phospholipid binding proteins with key functions in plasma membrane repair (PMR); an active mechanism to limit and mend cellular injury that involves membrane and cytoskeletal reorganizations. However, a role for direct membrane damage and PMR has not been well studied in the context of biomechanical strain, such as that associated with glaucoma. Here we report that this moderate strain surprisingly damages cell membranes to increase permeability in a calcium-dependent manner, and induces rapid aggregation of ANXA4 at injury sites. ANXA4 loss-of-function increases permeability, while exogenous ANXA4 reduces it. Furthermore, ANXA4 aggregation is associated with F-actin dynamics in vitro, and remarkably this interaction and aggregation signature is also observed in the glaucomatous ONH in patient samples. Together these studies link moderate biomechanical strain with direct membrane damage and actin dynamics, and identify an active PMR role for ANXA4 in new model of cell injury associated with glaucoma pathogenesis

Glycan distribution and density in native skin's stratum corneum

Background: The glycosylation of proteins on the surface of corneocytes is believed to play an important role in cellular adhesion in the stratum corneum (SC) of human skin. Mapping with accuracy the localization of glycans on the surface of corneocytes through traditional methods of immunohistochemistry and electron microscopy remains a challenging task as both approaches lack enough resolution or need to be performed in high vacuum conditions. Materials and methods: We used an advanced mode of atomic force microscope (AFM), with simultaneous topography and recognition imaging to investigate the distribution of glycans on native (no chemical preparation) stripped samples of human SC. The AFM cantilever tips were functionalized with antiheparan sulfate antibody and the lectin wheat germ agglutinin (WGA) which binds specifically to Nacetyl glucosamine and sialic acid. Results: From the recognition imaging, we observed the presence of the sulfated glycosaminoglycan, heparan sulfate, and the glycans recognized by WGA on the surface of SC corneocytes in their native state. These glycans were found associated with beadlike domains which represent corneodesmosomes in the SC layers. Glycan density was calculated to be 1200 molecules/m2 in lower layers of SC compared to an important decrease, (106 molecules/m2) closer to the surface due probably to corneodesmosome degradation. Conclusion: Glycan spatial distribution and degradation is first observed on the surface of SC in native conditions and at high resolution. The method used can be extended to precisely localize the presence of other macromolecules on the surface of skin or other tissues where the maintenance of its native state is required.F35(VLID)356402