Ability of Lactobacillus gasseri K 7 to inhibit Escherichia coli adhesion in vitro on Caco-2 cells and ex vivo on pigs' jejunal tissue

The ability of Lactobacillus (Lb.) gasseri K 7 to inhibit adhesion of Escherichia coli O8:K88 to intestinal mucosa was studied on cultured Caco-2 cells and ex vivo on pigs' small intestinal tissue. Lactobacilli were added simultaneously with E. coli, before E. coli and after E. coli for competition, exclusion and displacement assays. The concentration of lactobacilli on fully differentiated Caco-2 cells was 4.5+/-0.3 x 10(8) cfu/well, while the concentration of E. coli varied from 1.5 x 10(6) to 4.3 x 10(8) cfu/well. The number of E. coli adhered to Caco-2 monolayer (cfu/well) was lineary correlated (R(2)=0.97) to the concentration of added cells. In the assay simulating exclusion, E. coli adhesion was reduced by Lb. gasseri K 7 strain by 0.1 to 0.6 log cfu/well. The binding of E. coli was inhibited even more when incubated simultaneously with lactobacilli, particularly at the lowest concentration of E. coli (ratio E. coli/lactobacilli 1:248), where five-times reduction (or 0.7 log) was observed. When adhesion to tissue derived from pigs' jejunum was tested, concentration of E. coli was constant (6.9+/-0.14 x 10(7) cfu/ml), while the concentration of Lb. gasseri K 7 was 5.9 x 10(7) and 1.3 x 10(7) cfu/ml in two independent experiments, respectively. The adhesion of E. coli and Lb. gasseri K 7 cells to jejunal mucosa was similar (1.0+/-0.17 x 10(6) and 1.54+/-0.10 x 10(6) cfu/cm(2)) when the concentrations of single strains in suspensions were approximately the same. No significant competition, exclusion or displacement of E. coli by lactobacilli was observed on jejunal tissue. In conclusion, Lb. gasseri K 7 was found to be effective in reducing E. coli adhesion to Caco-2 enterocytes, but it was not able to do so in ex vivo conditions tested for pig jejunal tissue.     

Recycled Polyolefin Blends: Effect of Modified Natural Zeolite on their Properties and Morphology

The purpose of this study is to investigate the effect of treated natural zeolite on the flow behavior, morphology, thermal, and mechanical properties in recycled polyolefin blends. A model polymer blend consisting of 95 wt% polyolefines and 5 wt% polystyrene was studied. Compositions from this recycled blend and dehydrated zeolite in a narrow concentration range (0–5 wt%) were treated with maleic anhydride-grafted polypropylene and initiator dicumyl peroxide. The compositions were characterized by capillary rheometry, wide-angle X-ray scattering, differential scanning calorimetry, scanning electron microscopy, and mechanical tests. The results show a compatibilizing effect of treated zeolite expressed by increase of shear viscosity and improvement of interfacial interactions and impact strength. The results can open wide possibilities for utilization of treated zeolite in recycling of unsorted polymer wastes.     

A delta9 desaturase from Bombus lucorum males: investigation of the biosynthetic pathway of marking pheromones

The knowledge of the molecular basis of communication in bumblebee communities is limited. None of the enzymes that participate in pheromone production have been characterized. Here, we cloned the gene encoding the Delta(9) desaturase from cDNA prepared from the total RNA of the pheromone gland and fat bodies of Bombus lucorum male. Functional expression of BlucNPVE desaturase in Saccharomyces cerevisiae and GC-MS analyses revealed its preference for C(18) saturated fatty acids. This suggests that Delta(9) desaturase is involved in the desaturation of metabolic fatty acids stored in triacylglyceroles (TAGs), because oleic acid is the most abundant fatty acid bound in TAG in B. lucorum and it is present in low concentration in the pheromone blend. The incubation of pheromone precursors with a dissected labial gland as well as direct injection of labelled pheromone substrates into B. lucorum males revealed that esterification of pheromone products occurs in the labial gland. These results support both the biosynthesis of pheromones from common lipids and the de novo synthesis of unsaturated pheromones in the labial gland.     

Microwave plasma‐initiated grafting of acrylic acid on Celgard 2500 membrane to prepare alkaline battery separators—Characteristics of process and product

A process of plasma‐initiated grafting of acrylic acid on commercial porous polypropylene membrane was studied. The influence of parameters of the plasma (power, gas pressure, time plasma‐sample distance, sample arrangement) and grafting (solvent composition, monomer concentration, time, inhibitor presence) on the degree of grafting, amount of homopolymer produced and surface electrical resistance was determined. A degree of grafting up to 18 mmol/g was obtained, which resulted in sample resistance as low as 30 mΩ cm². The molecular weight of AAc homopolymer that can be assumed as equal to the MW of grafted chains, ranged from 25,000 to 50,000,000 da. SEM and water permeability measurements show that grafting causes filling of the pores, which, however, does not stop K⁺ ions from penetrating the membrane. The performance of nickel‐cadmium cells with acrylic acid grafted membranes as separator is also presented. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Accelerated weathering of pectin/poly(vinyl alcohol) blends studied by spectroscopic methods

The blends of pectin (PEC) and poly(vinyl alcohol) (PVA) at different components ratios were prepared by mixing in water. Thin polymeric films of PEC/PVA blends and pure polymers were obtained by casting method. All samples were then artificially aged using Suntest apparatus (Atlas) up to 780 h. The changes in chemical structure during sample ageing have been monitored by infrared and ultraviolet‐visible absorption spectroscopies. The first stage of weathering (up to ～ 300 h) was very slow and alteration of chemical structure was negligible in all samples. Prolonged ageing (>300 h) caused more significant degradation processes. FTIR spectra exhibited the highest changes in hydroxyl and carbonyl band ranges indicating the efficient photooxidation of macromolecules. The mechanisms of the observed processes have been discussed. It was found that PVA undergoes faster photoxidative degradation than pectin aged at the same conditions. The PEC/PVA blends exhibited the improved resistance to weathering comparing with both polymers aged individually. Mutual stabilization effect can be explained by intermolecular interactions between PEC and PVA confirmed by spectroscopic methods. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Bonelike apatite formation on niobium metal treated in aqueous NaOH

The essential condition for a biomaterial to bond to the living bone is the formation of a biologically active bonelike apatite on its surface. In the present work, it has been demonstrated that chemical treatment can be used to create a calcium phosphate (CaP) surface layer, which might provide the alkali treated Nb metal with bone-bonding capability. Soaking Nb samples in 0.5 M NaOH, at 25 degrees C for 24 h produced a nano-porous approximately 40 nm thick amorphous sodium niobate hydrogel layer on their surface. Immersion in a simulated body fluid (SBF) lead to the deposition of an amorphous calcium phosphate layer on the alkali treated Nb. The formation of calcium phosphate is assumed to be a result of the local pH increase caused by the cathodic reaction of oxygen reduction on the finely porous surface of the alkali-treated metal. The local rise in pH increased the ionic activity product of hydroxyapatite and lead to the precipitation of CaP from SBF that was already supersaturated with respect to the apatite. The formation of a similar CaP layer upon implantation of alkali treated Nb into the human body should promote the bonding of the implant to the surrounding bone. This bone bonding capability could make Nb metal an attractive material for hard tissue replacements.     

Investigation of the applicability of dielectric relaxation properties of amino acid solutions within the resonant recognition model

The resonant recognition model (RRM) is a physicomathematical approach used to analyze the interactions of a protein and its target, using digital signal processing methods. The RRM is based on the finding that there is a significant correlation between the spectra of numerical presentation of protein sequences and their biological activities. Initially, the electron-ion interaction potential was used to represent each amino acid in the protein sequences. In this paper, the dielectric constant (/spl epsiv/') and dielectric loss tangent (tan /spl delta/) parameters have been determined for their possible use in the RRM. These parameters are based on the values of capacitance and conductance obtained experimentally for 20 amino acid solutions using dielectric spectroscopy for the case of the real component of dielectric permittivity; the parameter used is the dielectric increment (/spl Delta//spl epsiv/'), the difference between dielectric constant of the amino acid solution and that of the solvent alone. The results of multiple cross-spectral analyses have shown that parameters analyzed generate in the consensus spectrum one dominant peak corresponding to the common biological activity of proteins studied, allowing the conclusion that these new parameters are suitable for use in the RRM approach.     

Chromosomal location of the genetic determinants for bacteriocins produced by Lactobacillus gasseri K7

The production of similar or even identical bacteriocins by different lactic acid bacteria is not a rare event. To take advantage of this finding, genetic determinants of the Lactobacillus K7 bacteriocins were tested for putative homologies with previously described bacteriocins of the Lactobacillus acidophilus group through polymerase chain reaction (PCR). Among specific primer pairs of seven known bacteriocins, derived from their respective sequences, only acidocin LF221 A and B primers amplified fragments in chromosomal DNA of K7 strain that revealed strong similarity over small regions of LF221 bacteriocins. Treatment of Lactobacillus K7 with ethidium bromide and mitomycin C was ineffective in generating non-bacteriocinogenic derivatives and had no impact on plasmid loss either. Classification studies elucidated Lactobacillus K7 as a member of the Lactobacillus gasseri species.     

Inhibitors of Cyclin-Dependent Kinases: Types and Their Mechanism of Action

Recent studies on cyclin-dependent kinase (CDK) inhibitors have revealed that small molecule drugs have become very attractive for the treatment of cancer and neurodegenerative disorders. Most CDK inhibitors have been developed to target the ATP binding pocket. However, CDK kinases possess a very similar catalytic domain and three-dimensional structure. These features make it difficult to achieve required selectivity. Therefore, inhibitors which bind outside the ATP binding site present a great interest in the biomedical field, both from the fundamental point of view and for the wide range of their potential applications. This review tries to explain whether the ATP competitive inhibitors are still an option for future research, and highlights alternative approaches to discover more selective and potent small molecule inhibitors.