Transzygotic carcinogenic effect of nitrosoethylurea in rats

The results of two experiments on the transzygotic transfer of the nitrosoethylurea (NEU) carcinogenic effect are presented. In the first experiment female rats received 60 mg/kg b. w. of NEU at 16, 18 and 20th day of the pregnancy. Their F1 descendants developed multiple tumours of the nervous system after a short latency (up to 40 weeks). The rats of F2, F3, F4 and F5 generations which were not in a direct contact with NEU developed a statistically higher incidence of tumours occurring spontaneously (those of mammary gland, pituitary, and haematopoietic tissue). However, the incidence of nervous system tumours was at the level of controls. In the second experiment male rats received 80 mg/kg b. w. of NEU and then were mated with untreated females. The incidence of the nervous system tumours in the descendants of treated males was somewhat higher than in the controls. The manifestations and mechanisms of the transzygotic effect are discussed.     

The quality of run-off from an irrigated market garden area in Brazil

This paper presents the results of a study carried out in Brazil to determine the effects of irrigation and fertiliser use on the quality characteristics of run-off from an agricultural area used for intensive cultivation of market garden produce.The results show that during dry weather the discharge of nutrients from the cultivated area when irrigation is taking place is equivalent to 7 kg ha⁻¹ yr⁻¹ N and 1 kg ha⁻¹ yr⁻¹ P. Considerable accumulation of nutrients took place in the soil during the growing season, over the 129-day survey period the nutrient content of the top soil increased by approximately 590 g m⁻²N and P and 780 g m⁻²K. This accumulation was derived from fertilisers which were applied at rates of 1136 kg ha⁻¹N, 978 P and 1367 K. During wet weather the nutrients which had accumulated in the soil were washed out.     

Structure, orientation, and conformational changes in transmembrane domains of multidrug transporters

Multidrug transporter proteins promote the active transmembrane efflux of noxious drugs, thereby decreasing their accumulation in the intracellular medium and reducing their therapeutic efficiency. Expression of such proteins drastically reduces the efficiency of chemotherapeutic treatments against cancer and various infectious diseases. To overcome major difficulties related to the crystallization of membrane proteins, other experimental approaches have been developed to gain information on the structural changes involved in drug transport. We examine here and illustrate with a few examples how infrared and fluorescence spectroscopy can provide new insights into the structure of the membrane domains of multidrug transporters in particular. Such domains contain the drug-binding site(s) and mediate the passage of substrates across the cell membrane.     

Measurements and thermodynamic modeling of the solubility of squalene in supercritical carbon dioxide

The solubility of squalene in supercritical carbon dioxide (SC-CO₂) was measured and it was analyzed together with the values obtained by Catchpole and von Kamp (1997). The results showed that the experimental values obtained in this work agreed with the order of magnitude of those reported in the literature and correlated well with the Chrastil equation. The thermodynamic modeling using the Peng–Robinson equation of state only correlated well with the experimental values obtained when the critical properties and acentric factor reported by Ruivo et al. (2004) were used. The values predicted for the solubility of squalene in SC-CO₂ using modeling employing the GC-EOS, were only of the same order of magnitude as the experimental values for pressures below 200 bar, and its performance was influenced by the value of the critical hard sphere diameter.     

A double-layered carbon nanotube array with super-hydrophobicity

The growth of double-layered vertical-aligned carbon nanotube (CNT) arrays by a single step chemical vapor deposition is reported. The deactivation and reactivation of catalyst particles may be the cause of such a growth process. An interesting morphology difference between the top and the bottom CNT layers was observed. In contrast to the smooth surface of the top CNT layer, the surface of the bottom layer shows hierarchical structures. The surface structures of the bottom CNT layer allow this surface to exhibit super-hydrophobic properties and excellent self-cleaning abilities.     

Production and characterization of recombinant cyprosin B in Saccharomyces cerevisiae (W303-1A) strain

The Saccharomyces cerevisiae W303-1A strain transformed with a centromeric plasmid containing CYPRO11, which codifies the aspartic protease cyprosin B, was grown in a 3 l bioreactor under aerobic conditions. Expression of cyprosin B is directly dependent on the concentration of galactose used as the inducer and carbon source in 1% yeast extract, 2% bactopeptone, and 4% galactose in culture medium. For 4% of galactose, 209 mg.l(-1) total protein, and 1036 U.ml(-1) recombinant cyprosin B activity were obtained from 6.1 g dcw.l(-1) biomass. The recombinant cyprosin B, purified by two consecutive anion-exchange chromatographies (diethyl amino-ethyl [DEAE]-Sepharose and Q-Sepharose XK-16 columns), shows a specific activity of 62 x 10(3) U.mg(-1), corresponding to a purification degree of 12.5-fold and a recovery yield of 25.6% relative to that in fermentation broth. The proteolytic activity of recombinant cyprosin B is optimal at 42 degrees C and pH 4.5. The recombinant cyprosin B activity is 95% inhibited by pepstatin A, which confirms its aspartic protease nature. The pure recombinant cyprosin B is composed of two subunits, one with 14 and the other with 32 kDa. It exhibits clotting activity, similar to that of the natural enzyme from Cynara cardunculus flowers. The results reported here show that recombinant cyprosin B, the first clotting protease of plant origin produced in a bioreactor, can now be produced in large scale and may constitute a new and efficient alternative to enzymes of animal or fungal origin that are widely used in cheese making.     

Characterization of homofermentative lactobacilli isolated from kefir grains: potential use as probiotic

Considering that several health promoting properties are associated with kefir consumption and a reliable probiotic product requires a complete identification of the bacterial species, the present work evaluates several proved markers of probiotic potential of eleven isolates of homofermentative lactobacilli isolated from kefir grains and molecular identification and genotypic diversity. Using restriction analysis of amplified ribosomal DNA (ARDRA) and analysis of the 16S-23S rRNA internal spacer region we confirmed that all homofermentative lactobacilli belong to the species Lactobacillus plantarum. RAPD-PCR analysis allowed the discrimination of lactobacilli in five clusters. All isolates exhibited high resistance to bile salt. High survival after one hour of exposure to pH 2.5 was observed in Lb. plantarum CIDCA 8313, 83210, 8327 and 8338. All isolates were hydrophilic and non autoaggregative. Isolate CIDCA 8337 showed the highest percentage of adhesion among strains. All tested lactobacilli had strong inhibitory power against Salmonella typhimurium and Escherichia coli. Seven out of eleven isolates showed inhibition against Sal. enterica and five isolates were effective against Sal. gallinarum. Only CIDCA 8323 and CIDCA 8327 were able to inhibit Sal. sonnei. We did not find any correlation between the five clusters based on RAPD-PCR and the probiotic properties, suggesting that these isolates have unique characteristics.     

Oil recovery and lecithin production using water degumming sludge of crude soybean oils

BACKGROUND: Wet gums produced during aqueous degumming of crude soybean oils are currently processed to produce lecithin or added to meals to increase their nutritive value for animal feed. Oils occluded in these gums are generally not recovered or processed. In this work, three methods to recover occluded oil and obtain lecithin from wet gums were assayed: direct extraction of oil with cold acetone (Method I), extraction after water elimination under vacuum (Method II) and by solvent partition with hexane/ethanol (Method III). RESULTS: Higher oil yields (up to 588 g kg^?1 of occluded oil) were obtained when water was eliminated before extraction (Methods II and III). No significant differences were observed in lecithin yields between three methods (720–807 g kg^?1 of dried gums). Recovered oils had acidity = 16.7–21.7 g kg^?1 as oleic acid, TOTOX (total oxidation) values ≤ 8.82, unsaponifiable matter = 9.0–12.1 g kg^?1, and Phosphorus = 87–330 mg kg^?1. Lecithins obtained by Methods I, II and III hexane phase had the same purity level (610–691 g of total measured phospholipids kg^?1). CONCLUSIONS: The occluded oil in soybean wet gums can be recovered, with quality and stability indexes compatible with their reinsertion in the productive process, by water elimination and extraction with acetone. Lecithins can be obtained with different phospholipid composition and diverse application fields. Copyright © 2008 Society of Chemical Industry     

Breakage of wet flexible fiber agglomerates impacting a plane

The breakage of an agglomerate of wet flexible fibers impacting a plane is computationally investigated in this work using the discrete element method. In the agglomerate, the fibers stick together due to cohesive liquid bridge forces. Agglomerate breakage with various impact conditions, initial configurations, fiber properties, and liquid bridge properties is systematically investigated. The degree of breakage is governed by the impact energy, the cohesion energy due to liquid bridges, the energy dissipation/absorption through fiber–fiber contacts and fiber deformation, and the efficiency of force transmission within the agglomerate. More specifically, breakage is promoted by increasing impact velocity, decreasing agglomerate size, increasing initial compaction, increasing fiber bending modulus, decreasing liquid surface tension, and decreasing liquid-to-solid volume ratio. Breakage is strongly dependent on the modified Weber number, that is, the ratio of the Weber number to a dimensionless rupture distance, which is a measure of the impact energy relative to the cohesion energy.     

The importance of access to information and knowledge coordination on quality and economic benefits obtained from Six Sigma

Wireless Networks - This paper presents a structural equation model that relates knowledge coordination with access to information in the process of implementing Six Sigma and their impact on the...