A multiperipheral model with continued cross channel unitarity

We derive, by using a spectral representation in momentum transfer, t, an integral equation, similar in structure to a multipheral equation, with continued cross channel unitarity, for the absorptive part for a composite particle scattering amplitude from a Bethe-Salpeter equation describing composite particle scattering in the s channel. At high energy in the t channel, the equation becomes homogeneous and has a Reggeized solution. We indicate how this equation may be solved using determinental techniques. We also show how the composite particle amplitude resulting from the original equation may be used to construct production and three body amplitudes. We also infer the possibility of studying, using the amplitude from the cross channel problem, the effect of extra unitarity on Reggeon-Reggeon-particle vertices.     

Styrene Emulsion Polymerization above the CMC: New Evidence on Particle Nucleation by means of AFFFF

Summary: The number (N) and size distribution of particles (PSD) of a styrene emulsion polymerization above the CMC were studied by means of asymmetric flow‐field flow fractionation (AF⁴). Bimodal PSDs were obtained, suggesting that coagulation of the primary particles is not as extensive as would be expected, according to the coagulative mechanism. AF⁴ allowed it to be demonstrated that N is constant during interval II, and that the resolution limit of other particle sizing techniques can lead to erroneous mechanistic inferences, from the evolution of N.

Particle size distribution measured at low conversion for the emulsion polymerization of styrene, obtained by AF⁴ and DLS. The initial surfactant (S₀), initiator (I₀) and monomer (M₀) concentrations are indicated in the figure.     

Amino acid rejection behaviour as a function of concentration

The solute rejection versus concentration behaviour of five different amino acids has been investigated using a Nitto Denko NTR7450 nanofiltration membrane. The experimental data for amino acid rejection was also compared against a combined steric and charge rejection model. At its isoelectric point, lysine was effectively neutral and its behaviour was well described by the model incorporating a steric function only. For phenylalanine, the combined model was found to fit the data well. In contrast there was poor agreement between the model and rejection data for glutamine, glutamic acid and glycine whose rejection values at first increased with concentration. This result implied that another governing process was in operation. Dimerisation as an explanation for the observed phenomena was also investigated. Size analysis of amino acid molecules as a function of the prevailing concentration using dynamic light scattering was limited but showed no evidence of dimerisation. This data was supported by osmotic pressure measurements which demonstrated no evidence of non-linearity in the relation between osmotic pressure and concentration.     

Melanosomal damage in normal human melanocytes induced by UVB and metal uptake--a basis for the pro-oxidant state of melanoma

Melanins are ubiquitous catecholic pigments, formed in organelles called melanosomes within melanocytes, the function of which is to protect skin against harmful effects of UV radiation. Melanosomes within melanoma cells are characteristically abnormal, with fragmented melanin and disrupted membranes. We hypothesize that the disruption of melanosomal melanin might be an early event in the etiology and progression of melanoma, leading to increased oxidative stress and mutation. In this report, we examine the effect of a combination of UV treatment and metal ion exposure on melanosomes within melanocytes, as well as their ability to act as pro-oxidants in ex situ experiments, and assay the effects of this treatment on viability and cell cycle progression. UVB exposure causes morphologic changes of the cells and bleaching of melanosomes in normal melanocytes, both significantly enhanced in Cu(II) and Cd(II)-treated cells, as observed by microscopy. The promoted bleaching by Cu(II) is due to its ability to redox cycle under oxidative conditions, generating reactive oxygen species; verified by the observed enhancement of hydroxyl radical generation when isolated melanosomes were treated with both Cu(II) ions and UVB, as assayed by DNA clipping. Single-dose UVB/Cu treatment does not greatly affect cell viability or cell cycle progression in heavily pigmented cells, but did so in an amelanotic early stage melanoma cell line.     

On the localization of water-soluble porphyrins in micellar systems evaluated by static and time-resolved frequency-domain fluorescence techniques

Fluorescence quenching of meso-tetrakis-4-sulfonatophenyl (TPPS(4)) and meso-tetrakis-4-N-methylpyridil (TMPyP) porphyrins is studied in aqueous solution and upon addition of micelles of sodium dodecylsulfate (SDS), cetyltrimethylammonium chloride (CTAC), N-hexadecyl-N,N-dimethyl-3-ammonio-1-propanesulfonate (HPS) and t-octylphenoxypolyethoxyethanol (Triton X-100). Potassium iodide (KI) was used as quencher. Steady-state Stern-Volmer plots were best fitted by a quadratic equation, including dynamic (K(D)) and static (K(S)) quenching. K(S) was significantly smaller than K(D). Frequency-domain fluorescence lifetimes allowed estimating bimolecular quenching constants, k(q). At 25 degrees C, in aqueous solution, TMPyP shows k(q) values a factor of 2-3 higher than the diffusional limit. TPPS(4) shows collisional quenching with pH dependent k(q) values. For TMPyP quenching results are consistent with reported binding constants: a significant reduction of quenching takes place for SDS, a moderate reduction is observed for HPS and almost no change is seen for Triton X-100. Similar data were obtained at 50 degrees C. For CTAC-TPPS(4) system an enhancement of quenching was observed as compared to pure buffer. This is probably associated to accumulation of iodide at the cationic micellar interface. The attraction between CTAC headgroups and I(-), and repulsion between SDS and I(-), enhances and reduces the fluorescence quenching, respectively, of porphyrins located at the micellar interface. The small quenching of TPPS(4) in Triton X-100 is consistent with strong binding as reported in the literature.     

Detection and quantification of sucrose as dietary biomarker using gas chromatography and liquid chromatography with mass spectrometry

Several epidemiological studies suggest a link between the intake of refined sugars and an increased risk for colorectal, breast, pancreatic and endometrial cancer. However, other studies failed to confirm these conclusions and the reason for this may be the ambiguity of dietary assessment methods - mainly self-reporting - employed. Sucrose is an established biomarker for sugars intake, allowing the objective assessment of dietary sucrose. So far, urinary excretion of sucrose was mainly determined using an enzyme assay. However, this method is time-consuming and labour-intensive. In this study, we present a mass spectrometric method for the determination of sucrose in urine using liquid chromatography with mass spectrometry (LC/MS) which can be used for large-scale epidemiological studies.     

Predicted energies and structures associated with the mixed calcium strontium fluorapatites

Atomic scale local density functional simulations and configurational averaging are used to predict the energies and lattice parameters associated with mixed calcium/strontium fluorapatites, Ca_xSr_10−x(PO₄)₆F₂. In particular, the partition of Sr²⁺ and Ca²⁺ ions between the 6h and 4f cation sites is established across the entire compositional range. Lattice parameters and lattice volume are also analyzed as a function of Ca²⁺ to Sr²⁺ concentration and their cation site distribution. The predicted internal energy of mixing between the end members is used to discuss the available experimental data.     

Anti-idiotypic nanobody-alkaline phosphatase fusion proteins: Development of a one-step competitive enzyme immunoassay for fumonisin B1 detection in cereal

A rapid and sensitive one-step competitive enzyme immunoassay for the detection of FB₁ was developed. The anti-idiotypic nanobody–alkaline phosphatase (Ab2β−Nb−AP) was validated by the AP enzyme activity and the properties of bounding to anti-FB1-mAb (3F11) through colorimetric and chemiluminescence analyses. The 50% inhibitory concentration and the detection limit (LOD) of colorimetric enzyme-linked immunosorbent assay (ELISA) for FB₁ were 2.69 and 0.35 ng mL⁻¹, respectively, with a linear range of 0.93–7.73 ng mL⁻¹. The LOD of the chemiluminescence ELISA (CLIA) was 0.12 ng mL⁻¹, and the IC₅₀ was 0.89 ± 0.09 ng mL⁻¹ with a linear range of 0.29–2.68 ng mL⁻¹. Compared with LC-MS/MS, the results of this assay indicated the reliability of the Ab2β−Nb−AP fusion protein based one-step competitive immunoassay for monitoring FB₁ contamination in cereals. The Ab2β−Nb−AP fusion proteins have the potential to replace chemically-coupled probes in competitive enzyme immunoassay systems.     

Mango (Mangifera indica L.) Polyphenols: Anti-Inflammatory Intestinal Microbial Health Benefits,and Associated Mechanisms of Actions

Mango is rich in polyphenols including gallotannins and gallic acid, among others. The bioavailability of mango polyphenols, especially polymeric gallotannins, is largely dependent on the intestinal microbiota, where the generation of absorbable metabolites depends on microbial enzymes. Mango polyphenols can favorably modulate bacteria associated with the production of bioactive gallotannin metabolites including Lactobacillus plantarum, resulting in intestinal health benefits. In several studies, the prebiotic effects of mango polyphenols and dietary fiber, their potential contribution to lower intestinal inflammation and promotion of intestinal integrity have been demonstrated. Additionally, polyphenols occurring in mango have some potential to interact with intestinal and less likely with hepatic enzymes or transporter systems. This review provides an overview of interactions of mango polyphenols with the intestinal microbiome, associated health benefits and underlying mechanisms.