Poly(ethylene oxide)-grafted thermoplastic membranes for use as cellular hybrid bio-artificial organs in the central nervous system

Poly(acrylonitrile-co-vinyl chloride) (PAN/VC) anisotropic membranes were chemically modified with poly(ethylene oxide) (PEO) (5000 and 20,000 g/mol) by one of two aqueous reactions: (a) acid hydrolysis of the nitrile group to a carboxylic acid with which amine-terminated PEO (PEO-NH(2)) reacted or (b) base reduction of the nitrile group to an amine with which PEO-succinimide (PEO-SC) reacted. Approximately 1.3% of the bulk material was modified with PEO-NH(2) whereas 1.8 to 3.5% was modified with PEO-SC as determined by proton nuclear magnetic resonance ((1)H NMR) and attenuated total reflectance Fourier transform infrared (ATR FTIR) spectra. Approximately 50 to 75% less bovine serum albumin (BSA) adsorbed to PEO-grafted single skin fibers than to unmodified PAN/VC. Transport properties of modified and unmodified fibers were compared by passive diffusion, convective nominal molecular weight cutoff, and hydraulic permeability. Neither hydraulic permeability nor nominal molecular weight cutoff of BSA changed appreciably after surface modification with PEO indicating that pore structure was not adversely affected by the chemistry involved in grafting poly(ethylene oxide). However, in the absence of any membrane conditioning, the apparent diffusion of alpha-chymotrypsinogen (24,000 g/mol) was enhanced in PEO-grafted PAN/VC fibers possibly as a result of reduced sorption of the permeating protein. In vivo biocompatibility in the brain tissue of rats was judged by histological assessment of the host's cellular response to fibers implanted for 30 days; biocompatibility of both PAN/VC and PAN/VC-g-PEO was satisfactory but improved slightly with PEO grafting. (c) 1994 John Wiley & Sons, Inc.     

Exclusion of the APC gene as the cause of a variant form of familial adenomatous polyposis (FAP)

Familial adenomatous polyposis (FAP) is a premalignant disease inherited as an autosomal dominant trait, characterized by hundreds to thousands of polyps in the colorectal tract. Recently, the syndrome has been shown to be caused by mutations in the APC (adenomatous polyposis coli) gene located on chromosome 5q21. We studied two families that both presented a phenotype different than that of the classical form of FAP. The most important findings observed in these two kindreds are (a) low and variable number of colonic polyps (from 5 to 100) and (b) a slower evolution of the disease, with colon cancer occurring at a more advanced age than in FAP in spite of the early onset of intestinal manifestations. To determine whether mutations of the APC gene are also responsible for this variant syndrome, linkage studies were performed by using a series of markers both intragenic and tightly linked to the APC gene. The results provide evidence for exclusion of the APC gene as the cause of the variant form of polyposis present in the two families described.     

Mechanism of Ozone Inactivation of Bacteriophage f2

The inactivation kinetics of bacteriophage f2 were studied by using ozone under controlled laboratory conditions. The phage were rapidly inactivated during the first 5 s of the reaction by 5 and 7 logs at ozone concentrations of 0.09 and 0.8 mg/liter, respectively. During the next 10 min, the phage were further inactivated at a slower rate in both treatments. The [³H]uridine-labeled f2 phage and its ribonucleic acid (RNA) were examined to elucidate the mechanism of ozone inactivation, utilizing adsorption to host bacteria, sucrose density gradient analysis, and electron microscopy. The specific adsorption of the phage was reduced by ozonation in the same pattern as plaque-forming unit reduction. RNA was released from the phage particles during ozonation, although it had reduced infectivity for spheroplasts. Electron microscopic examination showed that the phage coat was broken by ozonation into many protein subunit pieces and that the specific adsorption of the phage to host pili was inversely related to the extent of phage breakage. The RNA enclosed in the phage coat was inactivated less by ozonation than were whole phage, but inactivated more than naked RNA. These findings suggest that ozone breaks the protein capsid into subunits, liberating RNA and disrupting adsorption to the host pili, and that the RNA may be secondarily sheared by a reduction with and/or without the coat protein molecules, which have been modified by ozonation.     

Inhibiton by sulfanilamide of sporulation in Saccharomyces cerevisiae.

The antimetabolite sulfanilamide inhibits sporulation in Saccharomyces cerevisiae strain AP1. Cells exposed to sulfanilamide at various times during the sporulation process become progressively insensitive to the drug, although accumulation of sulfanilamide by the cells increases with time. Vegetative growth of AP1 is practically unaffected by sulfanilamide; pregrowth of the cells in the presence of the drug does not prevent sporulation. Thus, inhibition is confined to the meiotic phase of the cell cycle. Sensitivity to sulfanilamide is independent of pH. Increasing the time cells are exposed to sulfanilamide results in a progressive reduction of ascus formation; however, the inhibition is reversible since sporulation can occur in cells exposed to the drug for greater than 24 h. The drug arrests the cells at a point before commitment to sporulation, since yeast cells exposed to sulfanilamide for 12 h do not complete the sporulation process when returnedto vegetative medium, but resume mitotic growth instead. Meiotic nuclear division is largely prevented by sulfanilamide, and synthesis of RNA and protein is severely retarded. DNA synthesis is inhibited up to 50%; glycogen synthesis is approximately 90% inhibited. Other yeast strains showed varying sensitivity to sulfanilamide; homothallic strains were generally less affected.     

Isolation and characterization of cDNA clones to mouse macrophage and human endothelial cell tissue transglutaminases.

The deduced amino acid sequences for tissue transglutaminases from human endothelial cells and mouse macrophages have been derived from cloned cDNAs. Northern blot analysis of both tissue transglutaminases shows a message size of approximately 3.6-3.7 kilobases. The molecular weights calculated from the deduced amino acid sequences were 77,253 for human endothelial tissue transglutaminase and 76,699 for mouse macrophage tissue transglutaminase. The deduced amino acid sequence for the human endothelial transglutaminase was confirmed by comparison with the amino acid sequence obtained by cyanogen bromide digestion of the human erythrocyte transglutaminase. The amino acid sequences of both human endothelial and mouse macrophage tissue transglutaminases were compared to other transglutaminases. A very high degree of homology was found between human endothelial, mouse macrophage, and guinea pig liver tissue transglutaminase (greater than 80%). Moreover, human endothelial tissue transglutaminase was compared with human Factor XIIIa and a very high degree of homology (75% identity) was found in the active site region.     

Usefulness of the stomacher in a microbiological regulatory laboratory.

The relative efficiency of the Waring blender, the Stomacher 400, and the Stomacher 3500 for preparing food samples for microbiological analysis was studied. Comparative aerobic plate count (APC) values were determined on 671 samples, representing 30 categories of foods. Of the 26 categories of nonfatty foods, the blender gave significantly higher geometric mean APC values than those given by the Stomacher 400 and the Stomacher 3500 in 65 and 69 percent of the categories, respectively. In a comparison of the two Stomacher models, the Stomacher 400 gave significantly higher geometric mean APC values than these given by the Stomacher 3500 in 73 percent of the food categories. Addition of Tween 80 to four categories of fatty foods at concentrations of 0.5, 1.0, and 2.0 percent did not raise the APC values given by either model of stomacher to the levels given by the Waring blender. Overall, the efficiency of both models of Stomacher, relative to the blender and to each other, was specific and depended upon the particular food being analyzed.     

Conserving the functional and phylogenetic trees of life of European tetrapods

Protected areas (PAs) are pivotal tools for biodiversity conservation on the Earth. Europe has had an extensive protection system since Natura 2000 areas were created in parallel with traditional parks and reserves. However, the extent to which this system covers not only taxonomic diversity but also other biodiversity facets, such as evolutionary history and functional diversity, has never been evaluated. Using high-resolution distribution data of all European tetrapods together with dated molecular phylogenies and detailed trait information, we first tested whether the existing European protection system effectively covers all species and in particular, those with the highest evolutionary or functional distinctiveness. We then tested the ability of PAs to protect the entire tetrapod phylogenetic and functional trees of life by mapping species'' target achievements along the internal branches of these two trees. We found that the current system is adequately representative in terms of the evolutionary history of amphibians while it fails for the rest. However, the most functionally distinct species were better represented than they would be under random conservation efforts. These results imply better protection of the tetrapod functional tree of life, which could help to ensure long-term functioning of the ecosystem, potentially at the expense of conserving evolutionary history.     

Is interest toward the environment really declining? The complexity of analysing trends using internet search data

Recent analyses of internet search volume hypothesized a decline of public interest toward themes related to environment, biodiversity conservation and fishery. These analyses were based on Google Trends, which is a measure of how frequently a term is searched in Google, in proportion to the total of searches performed. Google Trends is a measure of relative search, and this may make difficult assessing temporal trends. I evaluated whether relative declines in internet search volumes represent genuine decline in interest toward environmental-related themes, by comparing trends of terms representing various themes, including environment, computer science, other disciplines (astrophysics) and leisure. Similar values of relative decline were detected for environmental terms, for computer science terms, and for other scientific disciplines. Conversely, an increase was observed for leisure related terms. This suggests that interest toward the environment is not truly decreasing. The apparent decline of environmental and scientific terms is most likely caused by the increasing use of internet for aims unrelated to science and technology, such as leisure. Internet search tools are a powerful source of information, but users should be aware of the complexity of analysing their data: using unrelated terms as benchmark may help to identify genuine trends.