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.     

Production of high transverse momentum prompt photons and neutral pions in proton-proton interactions at 280 GeV/c

The inclusive cross sections for production of prompt photons and π⁰ s by 280 GeV/c protons incident on a liquid hydrogen target, have been measured forp _T in the range 4.0 to 6.5 GeV/c and for |x _F |<0.45. A quantitative comparison of the prompt photon cross section with next-to-leading order QCD predictions using Duke and Owens structure functions is performed. Phenomenological fits to the π⁰ and prompt photon cross sections are given.     

Study of the π+π+π-π- system centrally 0 produced by incident π+ andp beams at 85 GeV/c

The reactions π⁺ p→π⁺(π⁺π⁺π^-π^-)p andpp→p(π⁺π⁺π^-π^-)p, where the (π⁺ π⁺ π^- π^-) system is centrally produced have been studied at 85 GeV/c. The π⁺π⁺π^-π^- mass spectrum shows evidence for thef ₁ (1285) meson with a mass of 1278±2 MeV and width 41±12 MeV which decays mainly through ρ⁰(770)π⁺π^-. Thef ₁(1285) is also observed in the ηπ⁺π^- channel. There is no significant evidence for ηππ or 4π decay modes of thef ₁(1420). The ρ⁰ρ⁰ production is found to be small. A Dalitz plot analysis of the 3π system shows evidence fora ₂ (1320) production and for a large contribution of theJ ^PC=1⁺⁺ ρπ wave.     

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.     

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.     

Analytical performance of the AtheNA MultiLyte® ANA II assay in sera from lupus patients with multiple positive ANAs

The purpose of this study was to evaluate the precision and accuracy of a commercial multiplexed kit for the measurement of 9 anti-nuclear antibodies (ANAs; anti-SS/A, anti-SS/B, anti-Sm, anti-RNP, anti-Jo-1, anti-Scl-70, anti-dsDNA, anti-Centromere B, and anti-Histone), and to compare these results to a subset of ANAs measured by enzyme-linked immunosorbent assays (ELISA) and immunodiffusion (ID). Sera were obtained from 22 systemic lupus erythematosus (SLE) patients, twelve controls and five others (commercial source) with various autoimmune diseases. ANA results from the AtheNA MultiLyte ANA II Assay (AtheNA) were compared to ELISA results (controls) and patients (ID). The AtheNA interassay coefficients of variation (CVs, N = 39, performed in duplicate; replicated 3x) ranged from 6.2% to 16.7% (mean = 9.8%), while the intra-assay CVs ranged from 5.8% to 14.3% (mean = 10.8%). Compared to results for SLE cases and controls, the sensitivity of AtheNA ranged from 85.7% to 100% (mean = 97.1%), while diagnostic specificity ranged from 16.7% to 100% (mean = 71.6%). There was significant agreement (P values ranging from 0.0001 to 0.03) when analytes coanalyzed by AtheNA and ELISA/ID were evaluated using Cohen's kappa (kappa values ranging from 0.376 to 1.000). No false positive ANA results were observed for either the control or commercial source autoimmune disease sera. These results indicate that the AtheNA assay is a precise and accurate alternative for performing multiple ELISAs or IDs in the diagnosis of autoimmune diseases, especially when the number of sera to be tested is large, such as in clinical screening or epidemiologic studies. It also appears that the AtheNA assay identifies positive ANA specificities which are missed by ID techniques, suggesting that it may have greater analytical sensitivity for some ANAs.     

Structure-based design of conformationally constrained cyclic peptidomimetics to target the MLL1-WDR5 protein–protein interaction as inhibitors of the MLL1 methyltransferase activity

We described herein structure-based design,synthesis and evaluation of conformationally constrained,cyclic peptidomimetics to block the MLL1-WDR5 protein–protein interaction as inhibitors of the MLL1 histone methyltransferase activity.Our study has yielded cyclic peptidomimetics with very high binding affinities to WDR5(Kivalues 1 nmol/L) and function as antagonists of the MLL1 histone methyltransferase activity.