In vitro lipid peroxidation of human serum catalyzed by cupric ion: antioxidant rather than prooxidant role of ascorbate.

The dual role of ascorbate as an antioxidant and a prooxidant has been clearly documented in the literature. Ascorbate acts as an antioxidant by protecting human serum from lipid peroxidation induced by azo dye-generated free radicals. On the other hand, ascorbate is readily oxidized in the presence of transition metal ions, (especially cupric ion) and accelerates lipid peroxidation in tissue homogenates by producing free radicals. Interestingly, we observed an antioxidant rather than an expected prooxidant role of ascorbate when human serum supplemented with 1.2mmol/L ascorbate underwent lipid peroxidations initiated by 2mmol/L copper sulfate. The antioxidant role of ascorbate was confirmed by studying the conventional thiobarbituric acid reactive substances (TBARS) as well as by observing the protective effect of ascorbate on the copper-induced peroxidation of unsaturated and polyunsaturated fatty acids. The antioxidation protection provided by ascorbate was comparable to that of equimolar alpha-tocopherol when incubated for 24h. However, lipid peroxidation products were lower in serum supplemented with alpha-tocopherol after 48h of incubation. This effect may be attributed to the binding of copper by plpha-tocopherol after serum proteins, thus preventing direct interaction between cupric ions and ascorbate. This proposed mechanism is based on the observation that the concentration of ascorbate decreased more slowly in serum than in phosphate buffer at physiological pH. Our results also indicate an outstanding anti-oxidant property of human serum due to the chelation of transition metal ions (even at high concentrations) by various serum proteins.     

Effect of Cytochalasin B, Lantrunculin B, Colchicine, Cycloheximid, Dimethyl Sulfoxide and Ion Channel Inhibitors on Biospeckle Activity in Apple Tissue

The biospeckle phenomenon is used for non-destructive monitoring the quality of fresh fruits and vegetables, but in the case of plant tissues there is a lack of experimentally confirmed information about the biological origin of the biospeckle activity (BA). As a main sources of BA, processes associated with the movement inside the cell, such as cytoplasmic streaming, organelle movement and intra- and extracellular transport mechanisms, are considered. The aim of this study is to investigate the effect of metabolism inhibitors, connected with intracellular movement such as cytochalasin B, lantrunculin B, colchicine, cycloheximid, dimethyl sulfoxide (DMSO) and mixture of ion channel inhibitors, injected into apples, on BA. Two methods of BA analysis based on cross-correlation coefficient and Laser Speckle Contrast Analysis (LASCA) were used. DMSO, lantrunculin B and mixture of ion channel inhibitors have a significant effect on BA, and approximately 74 % of BA of apple tissue is potentially caused by biological processes. Results indicate that the functioning of actin microfilaments and ion channels significantly affect BA.     

Raman imaging of changes in the polysaccharides distribution in the cell wall during apple fruit development and senescence

Planta - Du ring on-tree ripening, the pectin distribution changed from polydispersed in cell wall to cumulated in cell wall corners. During apple storage, the pectin distribution returned to...     

Expression of p21 and bcl-2 proteins and p53 mRNA in surgically resected preparations of non-small cell lung cancer (stage IIIA) after etoposide and cisplatin chemotherapy

Apoptosis which is also a called programmed cell death plays an important role during development, homeostasis and in many diseases such as cancer. Apoptosis is a genetically encoded cell death program defined by characteristic morphological and biochemical features. It is well recognized as a distinct pathologic mechanism in tumours responding to anticancer therapies. Many genes play an important role in this process. We evaluated an expression of the tumour supressor gene p53 and proteins p21 and bcl-2 in non-small cell lung cancer. We examined resected tumour tissues from 30 patients who received neoadjuvant chemotherapy. As a control we assessed tissues from patients treated without chemotherapy. Histological slides of the resected tumours were evaluated by TUNEL, in situ hybridisation and with immunoperoxidase staining procedure. The results were documented by photography. We examined the level of extinction using cytophotometry. In conclusion, preoperative chemotherapy induces apoptosis in cancer cells. The level of p53 correlates with the acceleration of TUNEL reaction. The loss of bcl-2 expression correlated with an increased apoptotic cell death. There was an increased p21 protein expression in the examined cancer tissues after chemotherapy.     

Multilayer nonnegative matrix factorization using projected gradient approaches

The most popular algorithms for Nonnegative Matrix Factorization (NMF) belong to a class of multiplicative Lee-Seung algorithms which have usually relative low complexity but are characterized by slow-convergence and the risk of getting stuck to in local minima. In this paper, we present and compare the performance of additive algorithms based on three different variations of a projected gradient approach. Additionally, we discuss a novel multilayer approach to NMF algorithms combined with multi-start initializations procedure, which in general, considerably improves the performance of all the NMF algorithms. We demonstrate that this approach (the multilayer system with projected gradient algorithms) can usually give much better performance than standard multiplicative algorithms, especially, if data are ill-conditioned, badly-scaled, and/or a number of observations is only slightly greater than a number of nonnegative hidden components. Our new implementations of NMF are demonstrated with the simulations performed for Blind Source Separation (BSS) data.     

Quantitative determination of albumin in urine by on-line immunoadsorptive cleanup and reversed-phase chromatography

Albumin in urine is selectively adsorbed on an immunoadsorber (human serum albumin-specific antibodies coupled covalently with a silica stationary phase) and after elution with 0.1% HCl is quantitatively determined by reversed-phase chromatography with detection of native fluorescence. The optimization of sample preparation and characteristics of the method such as recovery, linearity, reproducibility, detection limit, and selectivity are discussed.     

The solution structure of motilin from NMR distance constraints, distance geometry, molecular dynamics, and an iterative full relaxation matrix refinement

A model of the structure of the 22 amino acid residue gastrointestinal peptide hormone motilin in 30% hexafluoro-2-propanol has been obtained by using distance constraints obtained from two-dimensional nuclear Overhauser enhancements. A set of initial structures have been generated by using the distance geometry program DIANA, and 10 of these structures have been refined by using restrained molecular dynamics (AMBER). The resulting structures are virtually indistinguishable in terms of constraint violations and energies and display less than 0.5-A root mean square deviations (RMSD) of the backbone atom positions from Tyr7 to Lys20. A comparison of back-calculated and experimental NOE intensities indicates that RMSD's are not the best indicators of the goodness of fit or of the precision with which the structure is defined. The structure was further refined by fitting the experimental NOE data using an iterative full relaxation matrix analysis. The mean error between the observed and calculated backbone NOE intensities for the final refined structure was 0.23 for the full length of the molecule, 0.18 for the region from Glu9 to Lys20, and 0.29 for the region from Phe1 to Gly8. R factors for the same regions were 0.27, 0.19, and 0.43, respectively. All of the NOE-determined structures consistently display an alpha-helix which extends from Glu9 to Lys20. Considerable lack of definition of structure exists at the amino and carboxyl ends of the molecule and also in the vicinity of Thr6-Tyr7-Gly8. A tendency to form a wide turn appears to exist over the sequence Pro3-Ile4-Phe5-Thr6, but the structure in this region is not well defined by the NOE data.